Version bump for release 3.0.2 RC 1.

.gitattributes

@@ -1 +1,6 @@
+.gitignore export-ignore
+.gitattributes export-ignore
+.gitmodules export-ignore
+.travis.yml export-ignore
+
 tests/data/* linguist-documentation

.travis.yml

@@ -11,11 +11,15 @@ matrix:
             - boost-latest
           packages:
             - g++-5
-            - libboost1.55-all-dev
-            - libgtest-dev
+            - libboost-program-options1.55-dev
+            - libboost-iostreams1.55-dev
+            - libboost-system1.55-dev
+            - libboost-filesystem1.55-dev
       env: COMPILER=g++-5
 script:
+  - git submodule init
+  - git submodule update
   - mkdir build
   - cd build
   - cmake .. -DCMAKE_BUILD_TYPE=Debug -DBUILD_TESTS=ON -DCMAKE_CXX_COMPILER=$COMPILER
-  - make && make run-tests
+  - make -j3 && make -j3 run-tests

CHANGELOG.md

@@ -0,0 +1,36 @@
+# Change Log
+
+## (unreleased)
+
+Features:
+
+* unified translation format for SAS and PDDL files
+* documentation of `plasp`’s output format
+
+Bug Fixes:
+
+* fixes minor formatting issues in SAS translation
+
+## 3.0.1 (2016-06-14)
+
+Features:
+
+* basic support for parsing PDDL 3.1 domains and problems
+* limited support for translating PDDL 3.1 domains and problems to ASP facts
+* automatic language detection for PDDL and SAS
+* supports input from `std::cin`
+* supports colorized output
+* new command-line option `--language` to explicitly specify input language
+* new command-line option `--warning-level` to treat warnings as errors or to ignore warnings
+* new command-line option `--color` to autodetect, enable, or disable color output
+
+Bug Fixes:
+
+* fixes bug in translation of SAS axiom rules
+
+## 3.0.0 (2016-05-24)
+
+Features:
+
+* parses [SAS](http://www.fast-downward.org/TranslatorOutputFormat) files created with [Fast Downward](http://www.fast-downward.org/)
+* experimental translation from SAS to ASP facts

CMakeLists.txt

@@ -3,11 +3,11 @@ project(plasp CXX)
 
 find_package(Boost 1.55.0 COMPONENTS program_options iostreams system filesystem REQUIRED)
 
-set(CMAKE_CXX_FLAGS "-Wall -Wpedantic")
+set(CMAKE_CXX_FLAGS "-Wall -Wextra -Wpedantic")
 set(CMAKE_CXX_FLAGS_DEBUG "-g")
 add_definitions(-std=c++14)
 
-option(BUILD_TESTS "Build unit tests" OFF)
+option(BUILD_TESTS "Build unit tests" ON)
 
 set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)
 set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/lib)

LICENSE.md

@@ -1,6 +1,6 @@
-The MIT License (MIT)
+# The MIT License (MIT)
 
-Copyright (c) 2016 Patrick Lühne
+Copyright © 2016 Patrick Lühne
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -1,50 +1,70 @@
 # plasp—Translate PDDL to ASP
 
-[![Build Status](https://travis-ci.org/potassco/plasp.svg?branch=master)](https://travis-ci.org/potassco/plasp)
+[![GitHub Release](https://img.shields.io/github/release/potassco/plasp.svg?maxAge=3600)](https://github.com/potassco/plasp/releases)
+[![Build Status](https://img.shields.io/travis/potassco/plasp/develop.svg?maxAge=3600&label=build (master))](https://travis-ci.org/potassco/plasp?branch=master)
+[![Build Status](https://img.shields.io/travis/potassco/plasp/develop.svg?maxAge=3600&label=build (develop))](https://travis-ci.org/potassco/plasp?branch=develop)
 
 `plasp` 3 is in early development and not intended for productive use yet.
 
-As of now, `plasp` 3 experimentally supports the full [SAS Format](http://www.fast-downward.org/TranslatorOutputFormat) (as of version 3) used by [Fast Downward](http://www.fast-downward.org/).
+`plasp` translates planning problem instances to ASP facts.
+`plasp` 3 supports the input languages [PDDL 3.1](https://helios.hud.ac.uk/scommv/IPC-14/software.html) (only basic features currently) and [SAS](http://www.fast-downward.org/TranslatorOutputFormat) (full support of SAS 3), which is used by [Fast Downward](http://www.fast-downward.org/).
 
 Please get in touch with [Patrick Lühne](https://www.luehne.de) if you have any suggestions.
 
 ## Usage
 
-To translate an SAS file into ASP facts, call:
+### Translating PDDL to ASP Facts
+
+PDDL instances are translated to ASP facts as follows:
 
 ```bash
-$ plasp file.sas
+$ plasp domain.pddl problem.pddl
 ```
 
-For instance, a PDDL instance can be solved as follows.
-First, use [Fast Downward](http://www.fast-downward.org/) to translate the files from PDDL to SAS:
+Alternatively, PDDL instances may first be translated to SAS, the output format of [Fast Downward](http://www.fast-downward.org/).
 
 ```bash
-$ ./fast-downward.py --translate --build=release64 domain.pddl instance.pddl
+$ ./fast-downward.py --translate --build=release64 domain.pddl problem.pddl
 ```
 
-This creates the file `output.sas`.
-The translated SAS instance can now be solved incrementally with `clingo` and the meta encoding `meta-sequential-incremental.lp`:
+This creates a file called `output.sas`, which may now be translated by `plasp`.
 
 ```bash
-$ plasp output.sas > instance.lp
-$ clingo encodings/meta-sequential-incremental.lp instance.lp
+$ plasp output.sas
 ```
 
+### Solving the Translated Instance
+
+The translated instance can finally be solved incrementally with `clingo` and a meta encoding, for instance, `pddl-meta-sequential-incremental.lp`:
+
+```bash
+$ plasp domain.pddl problem.pddl > instance.lp
+$ clingo encodings/pddl-meta-sequential-incremental.lp instance.lp
+```
+
+## Command-Line Interface
+
+```bash
+$ plasp [files] [options]
+```
+
+`plasp` automatically detects the language of the input program.
+
+See [command-line interface](doc/command-line-interface.md) for more detail.
+
+## Output Format
+
+`plasp` provides a uniform output format for SAS and PDDL input problems.
+
+See [output format](doc/output-format.md) for more detail.
+
+If you want to write your own meta encoding for `plasp`’s output, this [simple example encoding](encodings/sequential-incremental.lp) gets you started.
+
 ## Building
 
-`plasp` requires a C++14 compiler (preferrably GCC ≥ 6.1), the `boost` libraries (≥ 1.55), and CMake for building.
+`plasp` requires `boost` and is built via CMake and a C++ compiler.
 
-```bash
-$ git clone https://github.com/potassco/plasp.git
-$ cd plasp
-$ mkdir -p build/release
-$ cd build/release
-$ cmake ../.. -DCMAKE_BUILD_TYPE=Release
-$ make
-```
-
-The built `plasp` binary is then located at `plasp/build/release/bin/plasp`.
+See [building instructions](doc/building-instructions.md) for more detail.
 
 ## Contributors
 
@@ -52,5 +72,5 @@ The built `plasp` binary is then located at `plasp/build/release/bin/plasp`.
 
 ### Earlier Versions
 
-* René Knaebel (`plasp` 2)
-* Murat Knecht (`plasp`)
+* René Knaebel
+* Murat Knecht

apps/plasp-app/main.cpp

@@ -1,9 +1,16 @@
+#include <algorithm>
 #include <iostream>
+#include <string>
 
 #include <boost/program_options.hpp>
 
+#include <plasp/LanguageDetection.h>
+#include <plasp/pddl/Description.h>
+#include <plasp/pddl/TranslatorASP.h>
 #include <plasp/sas/Description.h>
 #include <plasp/sas/TranslatorASP.h>
+#include <plasp/utils/LogStream.h>
+#include <plasp/utils/TranslatorException.h>
 
 int main(int argc, char **argv)
 {
@@ -13,7 +20,10 @@ int main(int argc, char **argv)
 	description.add_options()
 		("help,h", "Display this help message.")
 		("version,v", "Display version information.")
-		("input,i", po::value<std::string>(), "Specify the SAS input file.");
+		("input,i", po::value<std::vector<std::string>>(), "Specify the PDDL or SAS input file.")
+		("language,l", po::value<std::string>(), "Specify the input language (sas or pddl). Omit for automatic detection.")
+		("warning-level", po::value<std::string>()->default_value("normal"), "Specify whether to output warnings normally (normal), to treat them as critical errors (error), or to ignore them (ignore).")
+		("color", po::value<std::string>()->default_value("auto"), "Specify whether to colorize the output (always, never, or auto).");
 
 	po::positional_options_description positionalOptionsDescription;
 	positionalOptionsDescription.add("input", -1);
@@ -23,12 +33,14 @@ int main(int argc, char **argv)
 	const auto printHelp =
 		[&]()
 		{
-			std::cout << "Usage: plasp file [options]" << std::endl;
+			std::cout << "Usage: plasp [files] [options]" << std::endl;
 			std::cout << "Translate PDDL instances to ASP facts." << std::endl << std::endl;
 
 			std::cout << description;
 		};
 
+	plasp::utils::Logger logger;
+
 	try
 	{
 		po::store(po::command_line_parser(argc, argv)
@@ -40,7 +52,8 @@ int main(int argc, char **argv)
 	}
 	catch (const po::error &e)
 	{
-		std::cerr << "Error: " << e.what() << std::endl << std::endl;
+		logger.logError(e.what());
+		std::cout << std::endl;
 		printHelp();
 		return EXIT_FAILURE;
 	}
@@ -53,27 +66,108 @@ int main(int argc, char **argv)
 
 	if (variablesMap.count("version"))
 	{
-		std::cout << "plasp version 3.0.0" << std::endl;
+		std::cout << "plasp version 3.0.2-rc.1" << std::endl;
 		return EXIT_SUCCESS;
 	}
 
-	if (!variablesMap.count("input"))
+	const auto warningLevel = variablesMap["warning-level"].as<std::string>();
+
+	if (warningLevel == "error")
+		logger.setWarningLevel(plasp::utils::Logger::WarningLevel::Error);
+	else if (warningLevel == "ignore")
+		logger.setWarningLevel(plasp::utils::Logger::WarningLevel::Ignore);
+	else if (warningLevel == "normal")
+		logger.setWarningLevel(plasp::utils::Logger::WarningLevel::Normal);
+	else
 	{
-		std::cerr << "Error: No input file specified" << std::endl << std::endl;
+		logger.logError("unknown warning level “" + warningLevel + "”");
+		std::cout << std::endl;
+		printHelp();
+		return EXIT_FAILURE;
+	}
+
+	const auto colorPolicy = variablesMap["color"].as<std::string>();
+
+	if (colorPolicy == "auto")
+		logger.setColorPolicy(plasp::utils::LogStream::ColorPolicy::Auto);
+	else if (colorPolicy == "never")
+		logger.setColorPolicy(plasp::utils::LogStream::ColorPolicy::Never);
+	else if (colorPolicy == "always")
+		logger.setColorPolicy(plasp::utils::LogStream::ColorPolicy::Always);
+	else
+	{
+		logger.logError("unknown color policy “" + colorPolicy + "”");
+		std::cout << std::endl;
 		printHelp();
 		return EXIT_FAILURE;
 	}
 
 	try
 	{
-		const auto sasDescription = plasp::sas::Description::fromFile(variablesMap["input"].as<std::string>());
-		const auto sasTranslator = plasp::sas::TranslatorASP(sasDescription);
-		sasTranslator.translate(std::cout);
+		plasp::utils::Parser<plasp::utils::CaseInsensitiveParserPolicy> parser;
+
+		if (variablesMap.count("input"))
+		{
+			const auto &inputFiles = variablesMap["input"].as<std::vector<std::string>>();
+
+			std::for_each(inputFiles.cbegin(), inputFiles.cend(),
+				[&](const auto &inputFile)
+				{
+					parser.read(inputFile);
+				});
+		}
+		else
+			parser.read("std::cin", std::cin);
+
+		const auto detectLanguage =
+			[&]()
+			{
+				if (variablesMap.count("language") == 0)
+					return plasp::detectLanguage(parser);
+
+				const auto languageName = variablesMap["language"].as<std::string>();
+
+				return plasp::Language::fromString(languageName);
+			};
+
+		const auto language = detectLanguage();
+
+		if (language == plasp::Language::Type::Unknown)
+		{
+			logger.logError("unknown input language");
+			std::cout << std::endl;
+			printHelp();
+			return EXIT_FAILURE;
+		}
+
+		if (language == plasp::Language::Type::PDDL)
+		{
+			auto pddlLogger = logger;
+			auto context = plasp::pddl::Context(std::move(parser), std::move(pddlLogger));
+			auto description = plasp::pddl::Description::fromContext(std::move(context));
+			const auto translator = plasp::pddl::TranslatorASP(description, description.context().logger.outputStream());
+			translator.translate();
+		}
+		else if (language == plasp::Language::Type::SAS)
+		{
+			const auto description = plasp::sas::Description::fromParser(std::move(parser));
+			const auto translator = plasp::sas::TranslatorASP(description, logger.outputStream());
+			translator.translate();
+		}
+	}
+	catch (const plasp::utils::ParserException &e)
+	{
+		logger.logError(e.coordinate(), e.message());
+		return EXIT_FAILURE;
+	}
+	catch (const plasp::utils::TranslatorException &e)
+	{
+		logger.logError(e.what());
+		return EXIT_FAILURE;
 	}
 	catch (const std::exception &e)
 	{
-		std::cerr << "Error: " << e.what() << std::endl << std::endl;
-		printHelp();
+		logger.logError(e.what());
 		return EXIT_FAILURE;
 	}
 

doc/building-instructions.md

@@ -0,0 +1,40 @@
+# Building Instructions
+
+`plasp` requires a C++14 compiler (preferrably GCC ≥ 6.1 or clang ≥ 3.8), the `boost` libraries (≥ 1.55), and CMake for building.
+
+```bash
+$ git clone https://github.com/potassco/plasp.git
+$ cd plasp
+$ mkdir -p build/release
+$ cd build/release
+$ cmake ../.. -DCMAKE_BUILD_TYPE=Release
+$ make
+```
+
+The built `plasp` binary is then located at `plasp/build/release/bin/plasp`.
+
+To update `plasp` to the most recent version, perform the following steps:
+
+```bash
+$ cd plasp
+$ git pull
+$ cd build/release
+$ cmake .
+$ make
+```
+
+## Running the Tests
+
+`plasp` provides unit tests written using the [Google Test](https://github.com/google/googletest) framework.
+Before building and running the tests, make sure you have fetched the Google Test git submodule:
+
+```bash
+$ git submodule init
+$ git submodule update
+```
+
+Afterward, build and run the tests as follows:
+
+```bash
+$ make run-tests
+```

doc/command-line-interface.md

@@ -0,0 +1,18 @@
+# Command-Line Interface
+
+```bash
+$ plasp [files] [options]
+```
+
+`plasp` automatically detects the language of the input files.
+
+Multiple files may be provided in an arbitrary order.
+`[files]` may also be omitted, in which case the input is read from `std::cin`.
+
+`plasp` supports the following options:
+
+| **option**                        | **explanation**                                                                                                                   |
+|-----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------|
+| `-l` [ `--language` ]             | Specify the input language (`sas` or `pddl`). Omit for automatic detection.                                                       |
+| `--warning-level` arg (=`normal`) | Specify whether to output warnings normally (`normal`), to treat them as critical errors (`error`), or to ignore them (`ignore`). |
+| `--color` arg (=`auto`)           | Specify whether to colorize the output (`always`, `never`, or `auto`).                                                            |

doc/feature-requirements.md

@@ -0,0 +1,22 @@
+# Feature Requirements
+
+Feature requirements are part of `plasp`’s [output format](output-format.md).
+Currently, `plasp` detects feature requirements only for SAS problems.
+
+`plasp` supports the following feature requirements:
+
+SAS feature | description
+------------|------------
+`actionCosts` | actions have associated costs (see [action costs](output-format.md#action-costs))
+`axiomRules` | immediate actions are used, which are executed as soon as the preconditions are satisfied (see [axiom rules](output-format.md#axiom-rules))
+`conditionalEffects` | some effects of an action may have additional conditions (see [actions](output-format.md#actions))
+
+## Example
+
+The following specifies that the input problem has the two requirements `actionCosts` and `conditionalEffects`.
+
+```prolog
+% requirements
+requiresFeature(actionCosts).
+requiresFeature(conditionalEffects).
+```

doc/output-format.md

@@ -0,0 +1,202 @@
+# Output Format
+
+`plasp` 3 translates SAS and PDDL files into a uniform ASP fact format.
+
+## Overview
+
+Essentially, `plasp`’s output format consists of [state variables](#variables) that are modified by [actions](#actions) if their preconditions are fulfilled.
+Variables reference [entities](#constants-objects) that are affected by the actions.
+As with PDDL, the objective is to achieve a specific [goal](#goal) starting from an [initial state](#initial-state) by executing a sequence of actions.
+
+`plasp`’s variables correspond to the multivalued variables in SAS.
+PDDL predicates are turned into Boolean variables to make the output format consistent.
+
+Actions are modeled exactly as PDDL actions and SAS operators.
+
+## In a Nutshell
+
+The following illustrates `plasp`’s output format for the problem of turning switches on and off.
+
+```prolog
+% declares the type "type(switch)"
+type(type(switch)).
+
+% introduces a switch "constant(a)"
+constant(constant(a)).
+has(constant(a), type(switch)).
+
+% declares a variable "variable(on(X))" for switches X
+variable(variable(on(X))) :- has(X, type(switch)).
+
+% the variable may be true or false
+contains(variable(on(X)), value(on(X)), true)) :- has(X, type(switch)).
+contains(variable(on(X)), value(on(X)), false)) :- has(X, type(switch)).
+
+% declares the action "action(turnOn(X))", which requires switch X to be off and then turns it on
+action(action(turnOn(X))) :- has(X, type(switch)).
+precondition(action(turnOn(X)), variable(on(X)), value(on(X), false)) :- has(X, type(switch)).
+postcondition(action(turnOn(X)), effect(0), variable(on(X)), value(on(X), true)) :- has(X, type(switch)).
+
+% initially, the switch is off
+initialState(variable(on(constant(a))), value(on(constant(a)), false)).
+
+% in the end, the switch should be on
+goal(variable(on(constant(a))), value(on(constant(a)), true)).
+```
+
+## Syntax and Semantics
+
+`plasp` structures the translated ASP facts into multiple sections, which are explained in the following.
+
+### Feature Requirements
+
+```prolog
+% declares a required feature
+requires(feature(<name>)).
+```
+
+`plasp` recognizes and declares advanced features used by the input problem, such as conditional effects, [mutex groups](#mutex-groups) and [axiom rules](#axiom-rules) (currently only SAS).
+See the [full list of supported features](feature-requirements.md) for more information.
+
+The feature requirement predicates may be used in meta encodings to warn about unsupported features.
+
+### Types
+
+```prolog
+% declares a <type>
+type(type(<name>)).
+
+% specifies <constant> to be of type type(<name>)
+has(<constant>, type(<name>)).
+```
+
+[Variables](#variables), [constants](#constants-objects), and [objects](#constants-objects) may be typed. Types are only available with PDDL and if typing is enabled.
+
+### Variables
+
+```prolog
+% declares a <variable>
+variable(variable(<name>)).
+
+% adds a <value> to the domain of a <variable>
+contains(<variable>, <value>).
+```
+
+`plasp`’s variables represent the current state of the planning problem.
+Variables are linked to the problem's [objects](#constants-objects) and [constants](#constants-objects).
+
+`plasp`’s variables are multivalued, and each variable has exactly one value at each point in time.
+
+With SAS, variable names are numbers starting at 0, `variable(<number>)`.
+SAS variables are inherently multivalued, which results in two or more values of the form `value(<SAS predicate>, <bool>)` for each variable.
+
+With PDDL, Boolean variables are created from the PDDL predicates.
+Variables ared named after the PDDL predicates, `variable(<PDDL predicate>).`
+Each variable contains exactly two values (one `true`, one `false`) of the form `value(<PDDL predicate>, <bool>)`.
+Note that with PDDL, variables and values are named identically.
+
+### Actions
+
+```prolog
+% declares an <action>
+action(action(<name>)).
+
+% defines that as a precondition to <action>, <variable> must have value <value>
+precondition(<action>, <variable>, <value>).
+
+% defines that after applying <action>, <variable> is assigned <value>
+postcondition(<action>, effect(<number>), <variable>, <value>).
+
+% defines the condition of a conditional effect
+precondition(effect(<number>), <variable>, <value>).
+
+% specifies the costs of applying <action>
+costs(<action>, <number>).
+```
+
+Actions may require certain variables to have specific values in order to be executed.
+After applying an action, variables get new values according to the action's postconditions.
+
+Actions may have *conditional effects*, that is, certain postconditions are only applied if additional conditions are satisfied.
+For this reason, each conditional effect is uniquely identified with a predicate `effect(<number>)` as the second argument of the `postcondition` facts.
+The conditions of conditional effects are given by additional `precondition` facts that take the respective `effect(<number>)` predicates as the first argument.
+
+Unconditional effects are identified with `effect(unconditional)`.
+
+Conditional effects are currently only supported with SAS input problems.
+
+Actions may also have *action costs* required to apply them. Action costs are currently supported for SAS only.
+
+### Constants/Objects
+
+```prolog
+% declares a <constant> or object
+constant(constant(<name>)).
+
+% specifies <constant> to be of type type(<name>)
+has(<constant>, <type>).
+```
+
+Constants and objects are the entities that are affected by [actions](#actions), for instance, the blocks in a Blocks World problem.
+Constants are global for a domain, while objects are problem-specific.
+
+`plasp` does not distinguish between the two (modeling both as constants), as both are identically used static identifiers.
+
+### Initial State
+
+```prolog
+% initializes <variable> with a specific <value>
+initialState(<variable>, <value>).
+```
+
+The initial state contains all [variable](#variables) assignments that hold before executing any [actions](#actions).
+
+Note that with PDDL, the initial state might not assign values to all variables. Instead, unassigned values have to be assigned `false` manually.
+
+### Goal
+
+```prolog
+% specifies that <variable> shall obtain <value> in the end
+goal(<variable>, <value>).
+```
+
+The goal specifies all variable assignments that have to be fulfilled after executing the plan.
+
+### Mutex Groups
+
+```prolog
+% declares a <mutex group>
+mutexGroup(mutexGroup(<number>)).
+
+% adds the assignment of <variable> to <value> to a <mutex group>
+contains(<mutex group>, <variable>, <value>).
+```
+
+SAS contains information about mutually exclusive [variable](#variables) assignments.
+That is, *at most one* variable assignment of each mutex group must be satisfied at all times.
+
+Mutex group facts are only present with SAS input programs and not PDDL.
+
+Mutex groups contain essential information in order to find plans correctly.
+That is, if mutex groups are present in `plasp`’s output, they have to be accounted for appropriately.
+
+### Axiom Rules
+
+```prolog
+% declares an <axiom rule>
+axiomRule(axiomRule(<number>)).
+
+% defines that as a precondition to <axiom rule>, <variable> must have value <value>
+precondition(<axiom rule>, <variable>, <value>).
+
+% defines that after applying <axiom rule>, <variable> is assigned <value>
+postcondition(<axiom rule>, <variable>, <value>).
+```
+
+Axiom rules are similar to [actions](#actions) in that they modify [variables](#variables) if certain preconditions are satisfied.
+However, axiom rules must be applied *immediately* as soon as their preconditions are satisfied.
+
+Axiom rule facts are only present with SAS input programs and not PDDL.
+
+Axiom rules contain essential information in order to find plans correctly.
+That is, if axiom rules are present in `plasp`’s output, they have to be accounted for appropriately.

encodings/meta-sequential-incremental.lp

@@ -1,40 +0,0 @@
-#include <incmode>.
-
-% Check feature requirements
-:- requiresFeature(actionCosts).
-:- requiresFeature(axiomRules).
-:- requiresFeature(conditionalEffects).
-
-#program base.
-
-% Establish initial state
-holds(Var, Val, 0) :- initialState(Var, Val).
-
-#program step(t).
-
-% Perform actions
-1 {occurs(action(A), t) : action(A)} 1.
-
-% Check preconditions
-:- occurs(A, t), precondition(A, Var, Val), not holds(Var, Val, t - 1).
-
-% Apply effects
-caused(Var, Val, t) :- occurs(A, t), postcondition(A, _, Var, Val).
-modified(Var, t) :- caused(Var, Val, t).
-
-holds(Var, Val, t) :- caused(Var, Val, t).
-holds(Var, Val, t) :- holds(Var, Val, t - 1), not modified(Var, t).
-
-% Check that variables have unique values
-:- variable(X), Var = variable(X), not 1 {holds(Var, Val, t) : contains(Var, Val)} 1.
-
-% Check mutexes
-:- mutexGroup(X), M = mutexGroup(X), not {holds(Var, Val, t) : contains(M, Var, Val)} 1.
-
-#program check(t).
-
-% Verify that goal is met
-:- query(t), goal(Var, Val), not holds(Var, Val, t).
-
-#show query/1.
-#show occurs/2.

encodings/sequential-incremental.lp

@@ -0,0 +1,43 @@
+#include <incmode>.
+
+% Check feature requirements
+:- requiresFeature(actionCosts).
+:- requiresFeature(axiomRules).
+:- requiresFeature(conditionalEffects).
+
+#program base.
+
+% Establish initial state
+holds(Variable, Value, 0) :- initialState(Variable, Value).
+
+% Make unspecified initial state variables false by default (for PDDL)
+holds(variable(Variable), value(Variable, false), 0) :- variable(variable(Variable)), {initialState(variable(Variable), _)} 0.
+
+#program step(t).
+
+% Perform actions
+1 {occurs(Action, t) : action(Action)} 1.
+
+% Check preconditions
+:- occurs(Action, t), precondition(Action, Variable, Value), not holds(Variable, Value, t - 1).
+
+% Apply effects
+caused(Variable, Value, t) :- occurs(Action, t), postcondition(Action, _, Variable, Value).
+modified(Variable, t) :- caused(Variable, Value, t).
+
+holds(Variable, Value, t) :- caused(Variable, Value, t).
+holds(Variable, Value, t) :- holds(Variable, Value, t - 1), not modified(Variable, t).
+
+% Check that variables have unique values
+:- variable(Variable), not 1 {holds(Variable, Value, t) : contains(Variable, Value)} 1.
+
+% Check mutexes
+:- mutexGroup(MutexGroup), not {holds(Variable, Value, t) : contains(MutexGroup, Variable, Value)} 1.
+
+#program check(t).
+
+% Verify that goal is met
+:- query(t), goal(Variable, Value), not holds(Variable, Value, t).
+
+#show query/1.
+#show occurs/2.

include/plasp/Language.h

@@ -0,0 +1,36 @@
+#ifndef __PLASP__LANGUAGE_H
+#define __PLASP__LANGUAGE_H
+
+#include <plasp/utils/Parser.h>
+
+namespace plasp
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Language
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Language
+{
+	public:
+		enum class Type
+		{
+			Unknown,
+			PDDL,
+			SAS
+		};
+
+		static std::string toString(Type language);
+		static Language::Type fromString(const std::string &languageName);
+
+	public:
+		Language() = delete;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+
+#endif

include/plasp/LanguageDetection.h

@@ -0,0 +1,49 @@
+#ifndef __PLASP__LANGUAGE_DETECTION_H
+#define __PLASP__LANGUAGE_DETECTION_H
+
+#include <plasp/Language.h>
+#include <plasp/utils/Parser.h>
+
+namespace plasp
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// LanguageDetection
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Language::Type detectLanguage(utils::Parser<utils::CaseInsensitiveParserPolicy> &parser)
+{
+	parser.skipWhiteSpace();
+
+	// SAS begins with "begin_version"
+	if (parser.testAndSkip<std::string>("begin"))
+	{
+		parser.seek(0);
+		return Language::Type::SAS;
+	}
+
+	// Skip potential PDDL comments
+	while (parser.currentCharacter() == ';')
+	{
+		parser.skipLine();
+		parser.skipWhiteSpace();
+	}
+
+	// PDDL contains sections starting with "(define"
+	if (parser.testAndSkip<std::string>("(") && parser.testAndSkip<std::string>("define"))
+	{
+		parser.seek(std::ios::beg);
+		return Language::Type::PDDL;
+	}
+
+	parser.seek(std::ios::beg);
+	return Language::Type::Unknown;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+
+#endif

include/plasp/pddl/Action.h

@@ -0,0 +1,48 @@
+#ifndef __PLASP__PDDL__ACTION_H
+#define __PLASP__PDDL__ACTION_H
+
+#include <vector>
+
+#include <plasp/pddl/Expression.h>
+#include <plasp/pddl/expressions/Variable.h>
+#include <plasp/utils/Parser.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Action
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Action
+{
+	public:
+		static void parseDeclaration(Context &context, Domain &domain);
+
+	public:
+		const std::string &name() const;
+
+		const expressions::Variables &parameters() const;
+		const Expression *precondition() const;
+		const Expression *effect() const;
+
+	private:
+		Action() = default;
+
+		std::string m_name;
+
+		expressions::Variables m_parameters;
+		std::unique_ptr<Expression> m_precondition;
+		std::unique_ptr<Expression> m_effect;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/ConsistencyException.h

@@ -0,0 +1,57 @@
+#ifndef __PLASP__PDDL__CONSISTENCY_EXCEPTION_H
+#define __PLASP__PDDL__CONSISTENCY_EXCEPTION_H
+
+#include <exception>
+#include <string>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ConsistencyException
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class ConsistencyException: public std::exception
+{
+	public:
+		explicit ConsistencyException()
+		:	ConsistencyException("unspecified consistency error")
+		{
+		}
+
+		explicit ConsistencyException(const char *message)
+		:	ConsistencyException(static_cast<std::string>(message))
+		{
+		}
+
+		explicit ConsistencyException(const std::string &message)
+		:	m_message{message}
+		{
+		}
+
+		~ConsistencyException() throw()
+		{
+		}
+
+		const char *what() const throw()
+		{
+			if (m_message.empty())
+				return "unspecified consistency error";
+
+			return m_message.c_str();
+		}
+
+	private:
+		std::string m_message;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/Context.h

@@ -0,0 +1,70 @@
+#ifndef __PLASP__PDDL__CONTEXT_H
+#define __PLASP__PDDL__CONTEXT_H
+
+#include <memory>
+#include <unordered_map>
+#include <vector>
+
+#include <plasp/pddl/Parser.h>
+#include <plasp/utils/Logger.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Context
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Context
+{
+	public:
+		Context() = default;
+		~Context() = default;
+
+		explicit Context(Parser &&otherParser)
+		:	parser{std::move(otherParser)}
+		{
+		}
+
+		explicit Context(utils::Logger &&otherLogger)
+		:	logger{std::move(otherLogger)}
+		{
+		}
+
+		explicit Context(Parser &&otherParser, utils::Logger &&otherLogger)
+		:	parser{std::move(otherParser)},
+			logger{std::move(otherLogger)}
+		{
+		}
+
+		Context(const Context &other) = delete;
+		Context &operator=(const Context &other) = delete;
+
+		Context(Context &&other)
+		:	parser(std::move(other.parser)),
+			logger(std::move(other.logger))
+		{
+		}
+
+		Context &operator=(Context &&other)
+		{
+			parser = std::move(other.parser);
+			logger = std::move(other.logger);
+
+			return *this;
+		}
+
+		Parser parser;
+		utils::Logger logger;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/Description.h

@@ -0,0 +1,59 @@
+#ifndef __PLASP__PDDL__DESCRIPTION_H
+#define __PLASP__PDDL__DESCRIPTION_H
+
+#include <boost/filesystem/path.hpp>
+
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/Problem.h>
+#include <plasp/utils/Parser.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Description
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Description
+{
+	public:
+		static Description fromContext(Context &&context);
+		static Description fromStream(std::istream &istream);
+		static Description fromFile(const std::string &path);
+		static Description fromFiles(const std::vector<std::string> &paths);
+
+	public:
+		Context &context();
+		const Context &context() const;
+
+		const Domain &domain() const;
+
+		bool containsProblem() const;
+		const Problem &problem() const;
+
+	private:
+		Description();
+
+		void parse();
+		void findSections();
+
+		void checkConsistency();
+
+		Context m_context;
+
+		utils::Stream::Position m_domainPosition;
+		std::unique_ptr<Domain> m_domain;
+		utils::Stream::Position m_problemPosition;
+		std::unique_ptr<Problem> m_problem;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/Domain.h

@@ -0,0 +1,93 @@
+#ifndef __PLASP__PDDL__DOMAIN_H
+#define __PLASP__PDDL__DOMAIN_H
+
+#include <plasp/pddl/Action.h>
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+#include <plasp/pddl/Parser.h>
+#include <plasp/pddl/Requirement.h>
+#include <plasp/pddl/expressions/Constant.h>
+#include <plasp/pddl/expressions/PredicateDeclaration.h>
+#include <plasp/pddl/expressions/PrimitiveType.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Domain
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Domain
+{
+	public:
+		Domain(Context &context);
+
+	public:
+		void findSections();
+		void parse();
+
+		void setName(std::string name);
+		const std::string &name() const;
+
+		const Requirements &requirements() const;
+		bool hasRequirement(Requirement::Type requirementType) const;
+		void checkRequirement(Requirement::Type requirementType) const;
+
+		expressions::PrimitiveTypes &types();
+		const expressions::PrimitiveTypes &types() const;
+
+		expressions::Constants &constants();
+		const expressions::Constants &constants() const;
+
+		expressions::PredicateDeclarations &predicates();
+		const expressions::PredicateDeclarations &predicates() const;
+
+		std::vector<std::unique_ptr<Action>> &actions();
+		const std::vector<std::unique_ptr<Action>> &actions() const;
+
+		void checkConsistency();
+
+	private:
+		void parseSection();
+
+		void parseRequirementSection();
+		void computeDerivedRequirements();
+
+		void parseTypeSection();
+
+		void parseConstantSection();
+
+		void parsePredicateSection();
+
+		void parseActionSection();
+
+		Context &m_context;
+
+		std::string m_name;
+
+		utils::Stream::Position m_requirementsPosition;
+		Requirements m_requirements;
+
+		utils::Stream::Position m_typesPosition;
+		expressions::PrimitiveTypes m_types;
+
+		utils::Stream::Position m_constantsPosition;
+		expressions::Constants m_constants;
+
+		utils::Stream::Position m_predicatesPosition;
+		expressions::PredicateDeclarations m_predicates;
+
+		std::vector<utils::Stream::Position> m_actionPositions;
+		std::vector<std::unique_ptr<Action>> m_actions;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/Expression.h

@@ -0,0 +1,130 @@
+#ifndef __PLASP__PDDL__EXPRESSION_H
+#define __PLASP__PDDL__EXPRESSION_H
+
+#include <memory>
+
+#include <plasp/utils/Parser.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Expression
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Context;
+class Domain;
+class ExpressionContext;
+class ExpressionVisitor;
+class Problem;
+
+class Expression;
+using ExpressionPointer = std::unique_ptr<Expression>;
+using Expressions = std::vector<ExpressionPointer>;
+
+namespace expressions
+{
+class And;
+using AndPointer = std::unique_ptr<And>;
+
+class At;
+using AtPointer = std::unique_ptr<At>;
+
+class Constant;
+using ConstantPointer = std::unique_ptr<Constant>;
+using Constants = std::vector<ConstantPointer>;
+
+class Either;
+using EitherPointer = std::unique_ptr<Either>;
+
+class Imply;
+using ImplyPointer = std::unique_ptr<Imply>;
+
+class Not;
+using NotPointer = std::unique_ptr<Not>;
+
+class Or;
+using OrPointer = std::unique_ptr<Or>;
+
+class Predicate;
+using PredicatePointer = std::unique_ptr<Predicate>;
+using Predicates = std::vector<PredicatePointer>;
+
+class PredicateDeclaration;
+using PredicateDeclarationPointer = std::unique_ptr<PredicateDeclaration>;
+using PredicateDeclarations = std::vector<PredicateDeclarationPointer>;
+
+class PrimitiveType;
+using PrimitiveTypePointer = std::unique_ptr<PrimitiveType>;
+using PrimitiveTypes = std::vector<PrimitiveTypePointer>;
+
+class Unsupported;
+using UnsupportedPointer = std::unique_ptr<Unsupported>;
+
+class Variable;
+using VariablePointer = std::unique_ptr<Variable>;
+using Variables = std::vector<VariablePointer>;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Expression
+{
+	public:
+		enum class Type
+		{
+			And,
+			At,
+			Binary,
+			Constant,
+			Either,
+			Imply,
+			Not,
+			Or,
+			PredicateDeclaration,
+			Predicate,
+			PrimitiveType,
+			Unsupported,
+			Variable
+		};
+
+	public:
+		virtual ~Expression() = default;
+
+		virtual Type expressionType() const = 0;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+class ExpressionCRTP: public Expression
+{
+	public:
+		Type expressionType() const override final
+		{
+			return Derived::ExpressionType;
+		}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parseLiteral(Context &context, ExpressionContext &expressionContext);
+ExpressionPointer parseAtomicFormula(Context &context, ExpressionContext &expressionContext);
+
+ExpressionPointer parsePreconditionExpression(Context &context,
+	ExpressionContext &expressionContext);
+ExpressionPointer parseExpression(Context &context, ExpressionContext &expressionContext);
+
+ExpressionPointer parseEffectExpression(Context &context,
+	ExpressionContext &expressionContext);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/ExpressionContext.h

@@ -0,0 +1,38 @@
+#ifndef __PLASP__PDDL__EXPRESSION_CONTEXT_H
+#define __PLASP__PDDL__EXPRESSION_CONTEXT_H
+
+#include <plasp/pddl/Expression.h>
+#include <plasp/pddl/Requirement.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ExpressionContext
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class ExpressionContext
+{
+	public:
+		ExpressionContext(Domain &domain, expressions::Variables &parameters);
+		ExpressionContext(Domain &domain, Problem *problem, expressions::Variables &parameters);
+
+		bool hasRequirement(Requirement::Type requirementType) const;
+		void checkRequirement(Requirement::Type requirementType) const;
+
+		Domain &domain;
+		Problem *problem;
+
+		expressions::Variables &parameters;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/IO.h

@@ -0,0 +1,45 @@
+#ifndef __PLASP__PDDL__IO_H
+#define __PLASP__PDDL__IO_H
+
+#include <iostream>
+
+#include <plasp/pddl/Parser.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// IO
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline void skipSection(Parser &parser)
+{
+	size_t openParentheses = 1;
+
+	while (true)
+	{
+		const auto character = parser.currentCharacter();
+		parser.advance();
+
+		if (character == '(')
+			openParentheses++;
+		else if (character == ')')
+		{
+			openParentheses--;
+
+			if (openParentheses == 0)
+				return;
+		}
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/InitialState.h

@@ -0,0 +1,35 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__INITIAL_STATE_H
+#define __PLASP__PDDL__EXPRESSIONS__INITIAL_STATE_H
+
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// InitialState
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class InitialState
+{
+	public:
+		static std::unique_ptr<InitialState> parseDeclaration(Context &context,
+			ExpressionContext &expressionContext);
+
+	public:
+		const Expressions &facts() const;
+
+	private:
+		Expressions m_facts;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/Parser.h

@@ -0,0 +1,49 @@
+#ifndef __PLASP__PDDL__PARSER_H
+#define __PLASP__PDDL__PARSER_H
+
+#include <plasp/utils/Parser.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Parser
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class PDDLParserPolicy
+{
+	public:
+		static char transformCharacter(char c) noexcept
+		{
+			return std::tolower(c);
+		}
+
+		static bool isWhiteSpaceCharacter(char c)
+		{
+			return std::iswspace(c);
+		}
+
+		static bool isIdentifierCharacter(char c)
+		{
+			return c != '?'
+				&& c != '('
+				&& c != ')'
+				&& c != ';'
+				&& std::isgraph(c);
+		}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+using Parser = utils::Parser<PDDLParserPolicy>;
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/Problem.h

@@ -0,0 +1,85 @@
+#ifndef __PLASP__PDDL__PROBLEM_H
+#define __PLASP__PDDL__PROBLEM_H
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+#include <plasp/pddl/InitialState.h>
+#include <plasp/pddl/Parser.h>
+#include <plasp/pddl/Requirement.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Problem
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Problem
+{
+	public:
+		Problem(Context &context, Domain &domain);
+
+		void findSections();
+		void parse();
+
+		Domain &domain();
+		const Domain &domain() const;
+
+		const std::string &name() const;
+
+		const Requirements &requirements() const;
+		bool hasRequirement(Requirement::Type requirementType) const;
+		void checkRequirement(Requirement::Type requirementType) const;
+
+		expressions::Constants &objects();
+		const expressions::Constants &objects() const;
+
+		InitialState &initialState();
+		const InitialState &initialState() const;
+
+		const Expression &goal() const;
+
+		void checkConsistency();
+
+	private:
+		void parseRequirementSection();
+		void computeDerivedRequirements();
+
+		void parseDomainSection();
+
+		void parseObjectSection();
+
+		void parseInitialStateSection();
+
+		void parseGoalSection();
+
+		Context &m_context;
+		Domain &m_domain;
+
+		std::string m_name;
+
+		utils::Stream::Position m_domainPosition;
+
+		utils::Stream::Position m_requirementsPosition;
+		Requirements m_requirements;
+
+		utils::Stream::Position m_objectsPosition;
+		expressions::Constants m_objects;
+
+		utils::Stream::Position m_initialStatePosition;
+		std::unique_ptr<InitialState> m_initialState;
+
+		utils::Stream::Position m_goalPosition;
+		ExpressionPointer m_goal;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/Requirement.h

@@ -0,0 +1,72 @@
+#ifndef __PLASP__PDDL__REQUIREMENT_H
+#define __PLASP__PDDL__REQUIREMENT_H
+
+#include <vector>
+
+#include <plasp/pddl/Context.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Requirement
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Requirement;
+using Requirements = std::vector<Requirement>;
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Requirement
+{
+	public:
+		enum class Type
+		{
+			STRIPS,
+			Typing,
+			NegativePreconditions,
+			DisjunctivePreconditions,
+			Equality,
+			ExistentialPreconditions,
+			UniversalPreconditions,
+			QuantifiedPreconditions,
+			ConditionalEffects,
+			Fluents,
+			NumericFluents,
+			ObjectFluents,
+			ADL,
+			DurativeActions,
+			DurationInequalities,
+			ContinuousEffects,
+			DerivedPredicates,
+			TimedInitialLiterals,
+			Preferences,
+			Constraints,
+			ActionCosts,
+			GoalUtilities
+		};
+
+		static Requirement parse(Context &context);
+
+	public:
+		Requirement(Type type);
+
+		Type type() const;
+
+		std::string toPDDL() const;
+		std::string toASP() const;
+
+	private:
+		Type m_type;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/TranslatorASP.h

@@ -0,0 +1,51 @@
+#ifndef __PLASP__PDDL__TRANSLATOR_ASP_H
+#define __PLASP__PDDL__TRANSLATOR_ASP_H
+
+#include <plasp/pddl/Description.h>
+
+#include <iosfwd>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// TranslatorASP
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class TranslatorASP
+{
+	public:
+		explicit TranslatorASP(const Description &description, utils::LogStream &outputStream);
+
+		void translate() const;
+
+	private:
+		void translateDomain() const;
+		void translateTypes() const;
+		void translatePredicates() const;
+		void translateActions() const;
+
+		void translateProblem() const;
+		void translateInitialState() const;
+		void translateGoal() const;
+
+		void translateConstants(const std::string &heading, const expressions::Constants &constants) const;
+		void translateVariablesHead(const expressions::Variables &variables) const;
+		void translateVariablesBody(const expressions::Variables &variables) const;
+		void translateLiteral(const Expression &literal) const;
+		void translatePredicate(const expressions::Predicate &predicate) const;
+
+		const Description &m_description;
+		utils::LogStream &m_outputStream;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/pddl/expressions/And.h

@@ -0,0 +1,33 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__AND_H
+#define __PLASP__PDDL__EXPRESSIONS__AND_H
+
+#include <plasp/pddl/expressions/NAry.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// And
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class And: public NAry<And>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::And;
+
+		static const std::string Identifier;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/At.h

@@ -0,0 +1,105 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__AT_H
+#define __PLASP__PDDL__EXPRESSIONS__AT_H
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// At
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class At: public ExpressionCRTP<At>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::At;
+
+		template<typename ExpressionParser>
+		static AtPointer parse(Context &context, ExpressionContext &expressionContext,
+			ExpressionParser parseExpression);
+
+		static const size_t TimePointStart = std::numeric_limits<size_t>::max();
+		static const size_t TimePointEnd = std::numeric_limits<size_t>::max() - 1;
+
+	public:
+		At();
+
+		size_t timePoint() const;
+
+		const Expression *argument() const;
+
+	private:
+		void setArgument(const Expression *argument);
+		void setArgument(ExpressionPointer &&argument);
+
+		size_t m_timePoint;
+
+		const Expression *m_argument;
+		ExpressionPointer m_argumentStorage;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<typename ExpressionParser>
+AtPointer At::parse(Context &context, ExpressionContext &expressionContext,
+	ExpressionParser parseExpression)
+{
+	auto &parser = context.parser;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("(")
+		|| !parser.testIdentifierAndSkip("at"))
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	size_t timePoint;
+
+	const auto timePointPosition = parser.position();
+
+	if (parser.testIdentifierAndSkip("start"))
+		timePoint = TimePointStart;
+	else if (parser.testIdentifierAndSkip("end"))
+		timePoint = TimePointEnd;
+	else if (parser.probeNumber())
+	{
+		parser.seek(timePointPosition);
+		timePoint = parser.parse<size_t>();
+	}
+	else
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	auto expression = std::make_unique<At>(At());
+
+	expression->m_timePoint = timePoint;
+
+	context.parser.skipWhiteSpace();
+
+	// Parse argument
+	expression->setArgument(parseExpression(context, expressionContext));
+
+	parser.expect<std::string>(")");
+
+	return expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Binary.h

@@ -0,0 +1,111 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__BINARY_H
+#define __PLASP__PDDL__EXPRESSIONS__BINARY_H
+
+#include <plasp/pddl/ConsistencyException.h>
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+#include <plasp/pddl/expressions/Variable.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Binary
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+class Binary: public ExpressionCRTP<Derived>
+{
+	public:
+		template<typename ExpressionParser>
+		static std::unique_ptr<Derived> parse(Context &context,
+			ExpressionContext &expressionContext, ExpressionParser parseExpression);
+
+	public:
+		const std::array<const Expression *, 2> &arguments() const;
+
+	private:
+		template<size_t i>
+		void setArgument(const Expression *argument);
+		template<size_t i>
+		void setArgument(ExpressionPointer &&argument);
+
+		std::array<const Expression *, 2> m_arguments;
+		std::array<ExpressionPointer, 2> m_argumentStorage;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+template<typename ExpressionParser>
+std::unique_ptr<Derived> Binary<Derived>::parse(Context &context,
+	ExpressionContext &expressionContext, ExpressionParser parseExpression)
+{
+	auto &parser = context.parser;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("(")
+		|| !parser.testIdentifierAndSkip(Derived::Identifier))
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	auto expression = std::make_unique<Derived>();
+
+	// Assume that expression identifier (imply, exists, etc.) is already parsed
+	// Parse arguments of the expression
+	expression->Binary<Derived>::setArgument<0>(parseExpression(context, expressionContext));
+	expression->Binary<Derived>::setArgument<1>(parseExpression(context, expressionContext));
+
+	parser.expect<std::string>(")");
+
+	return expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+template<size_t i>
+void Binary<Derived>::setArgument(const Expression *expression)
+{
+	static_assert(i <= 2, "Index out of range");
+
+	m_argumentStorage[i] = nullptr;
+	m_arguments[i] = expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+template<size_t i>
+void Binary<Derived>::setArgument(ExpressionPointer &&expression)
+{
+	static_assert(i <= 2, "Index out of range");
+
+	m_argumentStorage[i] = std::move(expression);
+	m_arguments[i] = m_argumentStorage[i].get();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+const std::array<const Expression *, 2> &Binary<Derived>::arguments() const
+{
+	return m_arguments;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Constant.h

@@ -0,0 +1,64 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__CONSTANT_H
+#define __PLASP__PDDL__EXPRESSIONS__CONSTANT_H
+
+#include <plasp/pddl/Expression.h>
+#include <plasp/utils/Parser.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Constant
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Constant: public ExpressionCRTP<Constant>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Constant;
+
+		static void parseTypedDeclaration(Context &context, Domain &domain);
+		static void parseTypedDeclarations(Context &context, Domain &domain);
+		static void parseTypedDeclaration(Context &context, Problem &problem);
+		static void parseTypedDeclarations(Context &context, Problem &problem);
+
+		static Constant *parseAndFind(Context &context, const Domain &domain);
+		static Constant *parseAndFind(Context &context, const Problem &problem);
+
+	public:
+		const std::string &name() const;
+		const PrimitiveType *type() const;
+
+	private:
+		static ConstantPointer parseDeclaration(Context &context);
+		static void parseTypedDeclaration(Context &context, Domain &domain, Constants &constants);
+
+		static Constant *parseAndFind(const std::string &constantName, const Constants &constants);
+
+		Constant();
+
+		void setDirty(bool isDirty = true);
+		bool isDirty() const;
+
+		void setType(const PrimitiveType *parentType);
+
+		bool m_isDirty;
+
+		std::string m_name;
+
+		const PrimitiveType *m_type;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Either.h

@@ -0,0 +1,33 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__EITHER_H
+#define __PLASP__PDDL__EXPRESSIONS__EITHER_H
+
+#include <plasp/pddl/expressions/NAry.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Either
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Either: public NAry<Either>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Either;
+
+		static const std::string Identifier;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Imply.h

@@ -0,0 +1,33 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__IMPLY_H
+#define __PLASP__PDDL__EXPRESSIONS__IMPLY_H
+
+#include <plasp/pddl/expressions/Binary.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Imply
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Imply: public Binary<Imply>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Imply;
+
+		static const std::string Identifier;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/NAry.h

@@ -0,0 +1,117 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__N_ARY_H
+#define __PLASP__PDDL__EXPRESSIONS__N_ARY_H
+
+#include <plasp/pddl/ConsistencyException.h>
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+#include <plasp/pddl/expressions/Variable.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// NAry
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+class NAry: public ExpressionCRTP<Derived>
+{
+	public:
+		template<typename ExpressionParser>
+		static std::unique_ptr<Derived> parse(Context &context,
+			ExpressionContext &expressionContext, ExpressionParser parseExpression);
+
+	public:
+		const std::vector<const Expression *> &arguments() const;
+
+	private:
+		void addArgument(const Expression *argument);
+		void addArgument(ExpressionPointer &&argument);
+
+		std::vector<const Expression *> m_arguments;
+		Expressions m_argumentStorage;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+template<typename ExpressionParser>
+std::unique_ptr<Derived> NAry<Derived>::parse(Context &context,
+	ExpressionContext &expressionContext, ExpressionParser parseExpression)
+{
+	auto &parser = context.parser;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("(")
+		|| !parser.testIdentifierAndSkip(Derived::Identifier))
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	auto expression = std::make_unique<Derived>();
+
+	parser.skipWhiteSpace();
+
+	// Assume that expression identifier (and, or, etc.) is already parsed
+	// Parse arguments of the expression
+	while (parser.currentCharacter() != ')')
+	{
+		expression->addArgument(parseExpression(context, expressionContext));
+
+		parser.skipWhiteSpace();
+	}
+
+	if (expression->m_arguments.empty())
+		context.logger.logWarning(parser.coordinate(), "“" + Derived::Identifier + "” expressions should not be empty");
+
+	parser.expect<std::string>(")");
+
+	return expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+void NAry<Derived>::addArgument(const Expression *argument)
+{
+	if (!argument)
+		return;
+
+	m_arguments.emplace_back(argument);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+void NAry<Derived>::addArgument(ExpressionPointer &&argument)
+{
+	if (!argument)
+		return;
+
+	m_argumentStorage.emplace_back(std::move(argument));
+	m_arguments.emplace_back(m_argumentStorage.back().get());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+const std::vector<const Expression *> &NAry<Derived>::arguments() const
+{
+	return m_arguments;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Not.h

@@ -0,0 +1,77 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__NOT_H
+#define __PLASP__PDDL__EXPRESSIONS__NOT_H
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Not
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Not: public ExpressionCRTP<Not>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Not;
+
+		template<typename ExpressionParser>
+		static NotPointer parse(Context &context, ExpressionContext &expressionContext,
+			ExpressionParser parseExpression);
+
+	public:
+		Not();
+
+		const Expression *argument() const;
+
+	private:
+		void setArgument(const Expression *argument);
+		void setArgument(ExpressionPointer &&argument);
+
+		const Expression *m_argument;
+		ExpressionPointer m_argumentStorage;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<typename ExpressionParser>
+NotPointer Not::parse(Context &context, ExpressionContext &expressionContext,
+	ExpressionParser parseExpression)
+{
+	auto &parser = context.parser;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("(")
+		|| !parser.testIdentifierAndSkip("not"))
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	auto expression = std::make_unique<Not>(Not());
+
+	context.parser.skipWhiteSpace();
+
+	// Parse argument
+	expression->setArgument(parseExpression(context, expressionContext));
+
+	parser.expect<std::string>(")");
+
+	return expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Or.h

@@ -0,0 +1,33 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__OR_H
+#define __PLASP__PDDL__EXPRESSIONS__OR_H
+
+#include <plasp/pddl/expressions/NAry.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Or
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Or: public NAry<Or>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Or;
+
+		static const std::string Identifier;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Predicate.h

@@ -0,0 +1,50 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__PREDICATE_H
+#define __PLASP__PDDL__EXPRESSIONS__PREDICATE_H
+
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Predicate
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Predicate: public ExpressionCRTP<Predicate>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Predicate;
+
+		static PredicatePointer parse(Context &context, ExpressionContext &expressionContext);
+		static PredicatePointer parse(Context &context, const Problem &problem);
+
+	public:
+		const std::string &name() const;
+		const std::vector<const Expression *> &arguments() const;
+
+		bool isDeclared() const;
+
+	private:
+		Predicate();
+
+		void setDeclared();
+
+		bool m_isDeclared;
+
+		std::string m_name;
+		std::vector<const Expression *> m_arguments;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/PredicateDeclaration.h

@@ -0,0 +1,49 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__PREDICATE_DECLARATION_H
+#define __PLASP__PDDL__EXPRESSIONS__PREDICATE_DECLARATION_H
+
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PredicateDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class PredicateDeclaration: public ExpressionCRTP<PredicateDeclaration>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::PredicateDeclaration;
+
+		static void parse(Context &context, Domain &domain);
+
+	public:
+		const std::string &name() const;
+		const Variables &arguments() const;
+
+		bool isDeclared() const;
+
+	private:
+		PredicateDeclaration();
+
+		void setDeclared();
+
+		bool m_isDeclared;
+
+		std::string m_name;
+		Variables m_parameters;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/PrimitiveType.h

@@ -0,0 +1,55 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__PRIMITIVE_TYPE_H
+#define __PLASP__PDDL__EXPRESSIONS__PRIMITIVE_TYPE_H
+
+#include <plasp/pddl/ConsistencyException.h>
+#include <plasp/pddl/Expression.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PrimitiveType
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class PrimitiveType: public ExpressionCRTP<PrimitiveType>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::PrimitiveType;
+
+		static void parseDeclaration(Context &context, Domain &domain);
+		static void parseTypedDeclaration(Context &context, Domain &domain);
+
+		static PrimitiveType *parseAndFind(Context &context, Domain &domain);
+
+	public:
+		PrimitiveType();
+		PrimitiveType(std::string name);
+
+		const std::string &name() const;
+		const std::vector<const PrimitiveType *> &parentTypes() const;
+
+	private:
+		void setDirty(bool isDirty = true);
+		bool isDirty() const;
+
+		bool m_isDirty;
+
+		std::string m_name;
+
+		std::vector<const PrimitiveType *> m_parentTypes;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Type.h

@@ -0,0 +1,28 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__TYPE_H
+#define __PLASP__PDDL__EXPRESSIONS__TYPE_H
+
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Type
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression *parseExistingPrimitiveType(Context &context,
+	ExpressionContext &expressionContext);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Unsupported.h

@@ -0,0 +1,40 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__UNSUPPORTED_H
+#define __PLASP__PDDL__EXPRESSIONS__UNSUPPORTED_H
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Unsupported
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Unsupported: public ExpressionCRTP<Unsupported>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Unsupported;
+
+		static UnsupportedPointer parse(Context &context);
+
+	public:
+		const std::string &type() const;
+
+	private:
+		std::string m_type;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/pddl/expressions/Variable.h

@@ -0,0 +1,61 @@
+#ifndef __PLASP__PDDL__EXPRESSIONS__VARIABLE_H
+#define __PLASP__PDDL__EXPRESSIONS__VARIABLE_H
+
+#include <plasp/pddl/Expression.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Variable
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Variable: public ExpressionCRTP<Variable>
+{
+	public:
+		static const Expression::Type ExpressionType = Expression::Type::Variable;
+
+		static void parseTypedDeclaration(Context &context, ExpressionContext &expressionContext);
+		static void parseTypedDeclarations(Context &context, ExpressionContext &expressionContext);
+
+		static const Variable *parseAndFind(Context &context,
+			const ExpressionContext &expressionContext);
+
+	public:
+		const std::string &name() const;
+		const Expression *type() const;
+
+		void setDirty(bool isDirty = true);
+		bool isDirty() const;
+
+		void setType(const Expression *type);
+
+	private:
+		static void parseDeclaration(Context &context, Variables &parameters);
+
+	private:
+		Variable();
+
+		bool m_isDirty;
+
+		std::string m_name;
+
+		const Expression *m_type;
+
+		// Stores "either" expression if necessary
+		ExpressionPointer m_eitherExpression;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}
+
+#endif

include/plasp/sas/AssignedVariable.h

@@ -6,6 +6,7 @@
 
 #include <plasp/sas/Value.h>
 #include <plasp/sas/Variable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -26,8 +27,8 @@ using AssignedVariables = std::vector<AssignedVariable>;
 class AssignedVariable
 {
 	public:
-		static AssignedVariable fromSAS(std::istream &istream, const Variables &variables);
-		static AssignedVariable fromSAS(std::istream &istream, const Variable &variable);
+		static AssignedVariable fromSAS(utils::Parser<> &parser, const Variables &variables);
+		static AssignedVariable fromSAS(utils::Parser<> &parser, const Variable &variable);
 
 	public:
 		explicit AssignedVariable(const Variable &variable, const Value &value);

include/plasp/sas/AxiomRule.h

@@ -5,6 +5,7 @@
 
 #include <plasp/sas/AssignedVariable.h>
 #include <plasp/sas/Variable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -28,7 +29,7 @@ class AxiomRule
 		using Condition = AssignedVariable;
 		using Conditions = AssignedVariables;
 
-		static AxiomRule fromSAS(std::istream &istream, const Variables &variables);
+		static AxiomRule fromSAS(utils::Parser<> &parser, const Variables &variables);
 
 	public:
 		const Conditions &conditions() const;

include/plasp/sas/Debugging.h

@@ -16,7 +16,7 @@ namespace sas
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-std::ostream &operator >>(std::ostream &ostream, const Description &description);
+utils::LogStream &operator<<(utils::LogStream &ostream, const Description &description);
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 

include/plasp/sas/Description.h

@@ -13,6 +13,7 @@
 #include <plasp/sas/MutexGroup.h>
 #include <plasp/sas/Operator.h>
 #include <plasp/sas/Variable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -28,6 +29,7 @@ namespace sas
 class Description
 {
 	public:
+		static Description fromParser(utils::Parser<> &&parser);
 		static Description fromStream(std::istream &istream);
 		static Description fromFile(const boost::filesystem::path &path);
 
@@ -43,17 +45,21 @@ class Description
 		bool usesAxiomRules() const;
 		bool usesConditionalEffects() const;
 
+		bool hasRequirements() const;
+
 	private:
 		Description();
 
-		void parseVersionSection(std::istream &istream) const;
-		void parseMetricSection(std::istream &istream);
-		void parseVariablesSection(std::istream &istream);
-		void parseMutexSection(std::istream &istream);
-		void parseInitialStateSection(std::istream &istream);
-		void parseGoalSection(std::istream &istream);
-		void parseOperatorSection(std::istream &istream);
-		void parseAxiomSection(std::istream &istream);
+		void parseContent(utils::Parser<> &parser);
+
+		void parseVersionSection(utils::Parser<> &parser) const;
+		void parseMetricSection(utils::Parser<> &parser);
+		void parseVariablesSection(utils::Parser<> &parser);
+		void parseMutexSection(utils::Parser<> &parser);
+		void parseInitialStateSection(utils::Parser<> &parser);
+		void parseGoalSection(utils::Parser<> &parser);
+		void parseOperatorSection(utils::Parser<> &parser);
+		void parseAxiomSection(utils::Parser<> &parser);
 
 		bool m_usesActionCosts;
 

include/plasp/sas/Effect.h

@@ -5,6 +5,7 @@
 
 #include <plasp/sas/AssignedVariable.h>
 #include <plasp/sas/Variable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -28,7 +29,7 @@ class Effect
 		using Condition = AssignedVariable;
 		using Conditions = AssignedVariables;
 
-		static Effect fromSAS(std::istream &istream, const Variables &variables, Conditions &preconditions);
+		static Effect fromSAS(utils::Parser<> &parser, const Variables &variables, Conditions &preconditions);
 
 	public:
 		const Conditions &conditions() const;

include/plasp/sas/Goal.h

@@ -2,6 +2,7 @@
 #define __PLASP__SAS__GOAL_H
 
 #include <plasp/sas/AssignedVariable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -20,7 +21,7 @@ class Goal
 		using Fact = AssignedVariable;
 		using Facts = AssignedVariables;
 
-		static Goal fromSAS(std::istream &istream, const Variables &variables);
+		static Goal fromSAS(utils::Parser<> &parser, const Variables &variables);
 
 	public:
 		const Facts &facts() const;

include/plasp/sas/InitialState.h

@@ -2,6 +2,7 @@
 #define __PLASP__SAS__INITIAL_STATE_H
 
 #include <plasp/sas/AssignedVariable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -20,7 +21,7 @@ class InitialState
 		using Fact = AssignedVariable;
 		using Facts = AssignedVariables;
 
-		static InitialState fromSAS(std::istream &istream, const Variables &variables);
+		static InitialState fromSAS(utils::Parser<> &parser, const Variables &variables);
 
 	public:
 		const Facts &facts() const;

include/plasp/sas/MutexGroup.h

@@ -4,6 +4,7 @@
 #include <vector>
 
 #include <plasp/sas/AssignedVariable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -27,7 +28,7 @@ class MutexGroup
 		using Fact = AssignedVariable;
 		using Facts = AssignedVariables;
 
-		static MutexGroup fromSAS(std::istream &istream, const Variables &variables);
+		static MutexGroup fromSAS(utils::Parser<> &parser, const Variables &variables);
 
 	public:
 		const Facts &facts() const;

include/plasp/sas/Operator.h

@@ -8,6 +8,8 @@
 #include <plasp/sas/Effect.h>
 #include <plasp/sas/Predicate.h>
 #include <plasp/sas/Variable.h>
+#include <plasp/utils/LogStream.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -31,10 +33,10 @@ class Operator
 		using Condition = AssignedVariable;
 		using Conditions = AssignedVariables;
 
-		static Operator fromSAS(std::istream &istream, const Variables &variables);
+		static Operator fromSAS(utils::Parser<> &parser, const Variables &variables);
 
 	public:
-		void printPredicateAsASP(std::ostream &ostream) const;
+		void printPredicateAsASP(utils::LogStream &ostream) const;
 
 		const Predicate &predicate() const;
 		const Conditions &preconditions() const;

include/plasp/sas/Predicate.h

@@ -5,6 +5,9 @@
 #include <string>
 #include <vector>
 
+#include <plasp/utils/LogStream.h>
+#include <plasp/utils/Parser.h>
+
 namespace plasp
 {
 namespace sas
@@ -19,13 +22,13 @@ namespace sas
 class Predicate
 {
 	public:
-		static Predicate fromSAS(std::istream &istream);
+		static Predicate fromSAS(utils::Parser<> &parser);
 
 		using Arguments = std::vector<std::string>;
 
 	public:
-		void printAsSAS(std::ostream &ostream) const;
-		void printAsASP(std::ostream &ostream) const;
+		void printAsSAS(utils::LogStream &outputStream) const;
+		void printAsASP(utils::LogStream &outputStream) const;
 
 		const std::string &name() const;
 		const Arguments &arguments() const;

include/plasp/sas/TranslatorASP.h

@@ -2,6 +2,7 @@
 #define __PLASP__SAS__TRANSLATOR_ASP_H
 
 #include <plasp/sas/Description.h>
+#include <plasp/utils/LogStream.h>
 
 #include <iosfwd>
 
@@ -19,12 +20,21 @@ namespace sas
 class TranslatorASP
 {
 	public:
-		explicit TranslatorASP(const Description &description);
+		explicit TranslatorASP(const Description &description, utils::LogStream &outputStream);
 
-		void translate(std::ostream &ostream) const;
+		void translate() const;
 
 	private:
+		void translateRequirements() const;
+		void translateInitialState() const;
+		void translateGoal() const;
+		void translateVariables() const;
+		void translateActions() const;
+		void translateMutexes() const;
+		void translateAxiomRules() const;
+
 		const Description &m_description;
+		utils::LogStream &m_outputStream;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////

include/plasp/sas/Value.h

@@ -5,6 +5,9 @@
 #include <string>
 #include <vector>
 
+#include <plasp/utils/LogStream.h>
+#include <plasp/utils/Parser.h>
+
 namespace plasp
 {
 namespace sas
@@ -36,15 +39,15 @@ struct Value
 		static const Value Any;
 		static const Value None;
 
-		static Value fromSAS(std::istream &istream);
-		static const Value &referenceFromSAS(std::istream &istream, const Variable &variable);
+		static Value fromSAS(utils::Parser<> &parser);
+		static const Value &referenceFromSAS(utils::Parser<> &parser, const Variable &variable);
 
 	public:
 		Value negated() const;
 
-		void printAsSAS(std::ostream &ostream) const;
-		void printAsASP(std::ostream &ostream) const;
-		void printAsASPPredicate(std::ostream &ostream) const;
+		void printAsSAS(utils::LogStream &outputStream) const;
+		void printAsASP(utils::LogStream &outputStream) const;
+		void printAsASPPredicate(utils::LogStream &outputStream) const;
 
 		Sign sign() const;
 		const std::string &name() const;

include/plasp/sas/Variable.h

@@ -6,6 +6,8 @@
 #include <vector>
 
 #include <plasp/sas/Value.h>
+#include <plasp/utils/LogStream.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -26,11 +28,11 @@ using Variables = std::vector<Variable>;
 class Variable
 {
 	public:
-		static Variable fromSAS(std::istream &istream);
-		static const Variable &referenceFromSAS(std::istream &istream, const Variables &variables);
+		static Variable fromSAS(utils::Parser<> &parser);
+		static const Variable &referenceFromSAS(utils::Parser<> &parser, const Variables &variables);
 
 	public:
-		void printNameAsASPPredicate(std::ostream &ostream) const;
+		void printNameAsASPPredicate(utils::LogStream &outputStream) const;
 
 		const std::string &name() const;
 		int axiomLayer() const;

include/plasp/sas/VariableTransition.h

@@ -5,6 +5,7 @@
 
 #include <plasp/sas/Value.h>
 #include <plasp/sas/Variable.h>
+#include <plasp/utils/Parser.h>
 
 namespace plasp
 {
@@ -25,7 +26,7 @@ using VariableTransitions = std::vector<VariableTransition>;
 class VariableTransition
 {
 	public:
-		static VariableTransition fromSAS(std::istream &istream, const Variables &variables);
+		static VariableTransition fromSAS(utils::Parser<> &parser, const Variables &variables);
 
 	public:
 		const Variable &variable() const;

include/plasp/utils/Formatting.h

@@ -0,0 +1,203 @@
+#ifndef __PLASP__UTILS__FORMATTING_H
+#define __PLASP__UTILS__FORMATTING_H
+
+#include <iostream>
+
+#include <plasp/utils/LogStream.h>
+
+namespace plasp
+{
+namespace utils
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Formatting
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+enum class Color
+{
+	Black = 0,
+	Red = 1,
+	Green = 2,
+	Yellow = 3,
+	Blue = 4,
+	Magenta = 5,
+	Cyan = 6,
+	White = 7
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+enum class FontWeight
+{
+	Normal = 0,
+	Bold = 1
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Format
+{
+	Format(Color color, FontWeight fontWeight = FontWeight::Normal)
+	:	m_color{color},
+		m_fontWeight{fontWeight}
+	{
+	}
+
+	Color m_color;
+	FontWeight m_fontWeight;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline LogStream &operator<<(LogStream &stream, const Format &format)
+{
+	if (!stream.supportsColor())
+		return stream;
+
+	const auto fontWeightCode = static_cast<size_t>(format.m_fontWeight);
+	const auto colorCode = 30 + static_cast<size_t>(format.m_color);
+
+	return (stream << "\033[" << fontWeightCode << ";" << colorCode << "m");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct ResetFormat
+{
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline LogStream &operator<<(LogStream &stream, const ResetFormat &)
+{
+	if (!stream.supportsColor())
+		return stream;
+
+	return (stream << "\033[0m");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Token
+{
+	Token(const std::string &name)
+	:	name(name)
+	{
+	}
+
+	const std::string &name;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Keyword: public Token
+{
+	Keyword(const std::string &name)
+	:	Token(name)
+	{
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline LogStream &operator<<(LogStream &stream, const Keyword &keyword)
+{
+	return (stream
+		<< utils::Format(utils::Color::White, utils::FontWeight::Bold)
+		<< keyword.name
+		<< utils::ResetFormat());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Number: public Token
+{
+	Number(const std::string &name)
+	:	Token(name)
+	{
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline LogStream &operator<<(LogStream &stream, const Number &number)
+{
+	return (stream
+		<< utils::Format(utils::Color::Yellow, utils::FontWeight::Bold)
+		<< number.name
+		<< utils::ResetFormat());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Variable: public Token
+{
+	Variable(const std::string &name)
+	:	Token(name)
+	{
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline LogStream &operator<<(LogStream &stream, const Variable &variable)
+{
+	return (stream
+		<< utils::Format(utils::Color::Green, utils::FontWeight::Bold)
+		<< variable.name
+		<< utils::ResetFormat());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Heading1: public Token
+{
+	Heading1(const std::string &name)
+	:	Token(name)
+	{
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline LogStream &operator<<(LogStream &stream, const Heading1 &heading1)
+{
+	return (stream
+		<< utils::Format(utils::Color::Blue, utils::FontWeight::Bold)
+		<< "%---------------------------------------" << std::endl
+		<< "% " << heading1.name << std::endl
+		<< "%---------------------------------------"
+		<< utils::ResetFormat()
+		<< std::endl);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Heading2: public Token
+{
+	Heading2(const std::string &name)
+	:	Token(name)
+	{
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline LogStream &operator<<(LogStream &stream, const Heading2 &heading2)
+{
+	return (stream
+		<< utils::Format(utils::Color::Blue, utils::FontWeight::Bold)
+		<< "% " << heading2.name
+		<< utils::ResetFormat());
+}
+
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/utils/IO.h

@@ -1,17 +1,8 @@
-#ifndef __PLASP__UTILS__PARSING_H
-#define __PLASP__UTILS__PARSING_H
-
-#include <algorithm>
-#include <exception>
-#include <iosfwd>
-#include <sstream>
-#include <string>
-#include <typeinfo>
+#ifndef __PLASP__UTILS__IO_H
+#define __PLASP__UTILS__IO_H
 
 #include <boost/algorithm/string/replace.hpp>
 
-#include <plasp/utils/ParserException.h>
-
 namespace plasp
 {
 namespace utils
@@ -19,46 +10,10 @@ namespace utils
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 //
-// Parsing
+// IO
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-template<class T>
-T parse(std::istream &istream)
-{
-	T value;
-
-	try
-	{
-		istream >> value;
-	}
-	catch (const std::exception &e)
-	{
-		throw ParserException(std::string("Could not parse value of type ") + typeid(T).name() + " (" + e.what() + ")");
-	}
-
-	return value;
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
-template<class T>
-void parseExpected(std::istream &istream, const T &expectedValue)
-{
-	const auto value = parse<T>(istream);
-
-	if (value == expectedValue)
-		return;
-
-	std::stringstream errorStream;
-
-	errorStream << "Invalid format, expected " << expectedValue << ", got " + value;
-
-	throw utils::ParserException(errorStream.str());
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
 inline std::string escapeASP(const std::string &string)
 {
 	auto escaped = string;
@@ -85,6 +40,17 @@ inline std::string unescapeASP(const std::string &string)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+inline std::string escapeASPVariable(const std::string &string)
+{
+	auto escaped = escapeASP(string);
+
+	escaped.front() = std::toupper(escaped.front());
+
+	return escaped;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 }
 }
 

include/plasp/utils/LogStream.h

@@ -0,0 +1,289 @@
+#ifndef __PLASP__UTILS__LOG_STREAM_H
+#define __PLASP__UTILS__LOG_STREAM_H
+
+#include <iostream>
+#include <unistd.h>
+
+namespace plasp
+{
+namespace utils
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// LogStream
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+enum class StandardStream
+{
+	Out,
+	Err
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class LogStream
+{
+	public:
+		enum class ColorPolicy
+		{
+			Never,
+			Auto,
+			Always
+		};
+
+	private:
+		using CharacterType = std::ostream::char_type;
+		using TraitsType = std::ostream::traits_type;
+
+	public:
+		LogStream(StandardStream standardStream)
+		:	m_standardStream{standardStream},
+			m_colorPolicy{ColorPolicy::Auto}
+		{
+		}
+
+		LogStream(const LogStream &other)
+		:	m_standardStream{other.m_standardStream},
+			m_colorPolicy{other.m_colorPolicy}
+		{
+		}
+
+		LogStream &operator=(const LogStream &other)
+		{
+			m_standardStream = other.m_standardStream;
+			m_colorPolicy = other.m_colorPolicy;
+
+			return *this;
+		}
+
+		LogStream(LogStream &&other)
+		:	m_standardStream{other.m_standardStream},
+			m_colorPolicy{other.m_colorPolicy}
+		{
+			other.m_colorPolicy = ColorPolicy::Auto;
+		}
+
+		LogStream &operator=(LogStream &&other)
+		{
+			m_standardStream = other.m_standardStream;
+			m_colorPolicy = other.m_colorPolicy;
+
+			other.m_colorPolicy = ColorPolicy::Auto;
+
+			return *this;
+		}
+
+		void setColorPolicy(ColorPolicy colorPolicy)
+		{
+			m_colorPolicy = colorPolicy;
+		}
+
+		bool supportsColor() const
+		{
+			if (m_colorPolicy == ColorPolicy::Never)
+				return false;
+
+			if (m_colorPolicy == ColorPolicy::Always)
+				return true;
+
+			// Autodetect by checking whether output goes to a terminal
+			const auto fileDescriptor =
+				(m_standardStream == utils::StandardStream::Out)
+				? STDOUT_FILENO
+				: STDERR_FILENO;
+
+			return isatty(fileDescriptor);
+		}
+
+		std::ostream &ostream()
+		{
+			return (m_standardStream == utils::StandardStream::Out)
+				? std::cout
+				: std::cerr;
+		}
+
+		inline LogStream &operator<<(short value);
+		inline LogStream &operator<<(unsigned short value);
+		inline LogStream &operator<<(int value);
+		inline LogStream &operator<<(unsigned int value);
+		inline LogStream &operator<<(long value);
+		inline LogStream &operator<<(unsigned long value);
+		inline LogStream &operator<<(long long value);
+		inline LogStream &operator<<(unsigned long long value);
+		inline LogStream &operator<<(float value);
+		inline LogStream &operator<<(double value);
+		inline LogStream &operator<<(long double value);
+		inline LogStream &operator<<(bool value);
+		inline LogStream &operator<<(const void *value);
+		inline LogStream &operator<<(const char *value);
+		inline LogStream &operator<<(std::basic_streambuf<CharacterType, TraitsType> *sb);
+		inline LogStream &operator<<(std::ios_base &(*func)(std::ios_base &));
+		inline LogStream &operator<<(std::basic_ios<CharacterType, TraitsType> &(*func)(std::basic_ios<CharacterType, TraitsType> &));
+		inline LogStream &operator<<(std::basic_ostream<CharacterType, TraitsType> &(*func)(std::basic_ostream<CharacterType, TraitsType> &));
+
+	private:
+		StandardStream m_standardStream;
+		ColorPolicy m_colorPolicy;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(short value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(unsigned short value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(int value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(unsigned int value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(long value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(unsigned long value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(long long value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(unsigned long long value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(float value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(double value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(long double value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(bool value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(const void *value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(const char *value)
+{
+	ostream() << value;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(std::basic_streambuf<CharacterType, TraitsType>* sb)
+{
+	ostream() << sb;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(std::ios_base &(*func)(std::ios_base &))
+{
+	ostream() << func;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(std::basic_ios<CharacterType, TraitsType> &(*func)(std::basic_ios<CharacterType, TraitsType> &))
+{
+	ostream() << func;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+LogStream &LogStream::operator<<(std::basic_ostream<CharacterType, TraitsType> &(*func)(std::basic_ostream<CharacterType, TraitsType> &))
+{
+	ostream() << func;
+	return *this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class CharacterType, class Traits, class Allocator>
+inline LogStream &operator<<(LogStream &stream, const std::basic_string<CharacterType, Traits, Allocator> &string)
+{
+	stream.ostream() << string;
+	return stream;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/utils/Logger.h

@@ -0,0 +1,62 @@
+#ifndef __PLASP__UTILS__LOGGER_H
+#define __PLASP__UTILS__LOGGER_H
+
+#include <string>
+
+#include <plasp/utils/LogStream.h>
+#include <plasp/utils/ParserException.h>
+#include <plasp/utils/StreamCoordinate.h>
+
+namespace plasp
+{
+namespace utils
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Logger
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Logger
+{
+	public:
+		enum class WarningLevel
+		{
+			Normal,
+			Error,
+			Ignore
+		};
+
+	public:
+		Logger();
+
+		Logger(const Logger &other);
+		Logger &operator=(const Logger &other);
+
+		Logger(Logger &&other);
+		Logger &operator=(Logger &&other);
+
+		LogStream &outputStream();
+		LogStream &errorStream();
+
+		void setWarningLevel(WarningLevel warningLevel);
+		void setColorPolicy(LogStream::ColorPolicy colorPolicy);
+
+		void logError(const std::string &message);
+		void logError(const StreamCoordinate &coordinate, const std::string &message);
+		void logWarning(const StreamCoordinate &parserCoordinate, const std::string &message);
+
+	private:
+		LogStream m_outputStream;
+		LogStream m_errorStream;
+
+		WarningLevel m_warningLevel;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/utils/Parser.h

@@ -0,0 +1,559 @@
+#ifndef __PLASP__UTILS__PARSER_H
+#define __PLASP__UTILS__PARSER_H
+
+#include <iostream>
+#include <iterator>
+#include <sstream>
+#include <vector>
+
+#include <boost/filesystem.hpp>
+
+#include <plasp/utils/ParserException.h>
+#include <plasp/utils/ParserPolicy.h>
+#include <plasp/utils/Stream.h>
+#include <plasp/utils/StreamCoordinate.h>
+
+namespace plasp
+{
+namespace utils
+{
+
+template<typename Type>
+struct Tag
+{
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Parser
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy = CaseSensitiveParserPolicy>
+class Parser: public Stream, public ParserPolicy
+{
+	template<class OtherParserPolicy>
+	friend class Parser;
+
+	public:
+		explicit Parser();
+		explicit Parser(std::string streamName, std::istream &istream);
+
+		template<class OtherParser>
+		Parser(OtherParser &&otherParser)
+		{
+			m_stream = std::move(otherParser.m_stream);
+			m_delimiters = std::move(otherParser.m_delimiters);
+		}
+
+		void removeComments(const std::string &startSequence, const std::string &endSequence, bool removeEnd);
+
+		char currentCharacter() const;
+
+		template<typename Type>
+		Type parse();
+
+		template<typename Type>
+		bool testAndReturn(const Type &expectedValue);
+
+		template<typename Type>
+		bool testAndSkip(const Type &expectedValue);
+
+		template<typename Type>
+		void expect(const Type &expectedValue);
+
+		std::string parseIdentifier();
+		bool testIdentifierAndReturn(const std::string &identifier);
+		bool testIdentifierAndSkip(const std::string &identifier);
+
+		// TODO: remove
+		bool probeNumber();
+
+		std::string parseLine();
+
+		void skipWhiteSpace();
+		void skipLine();
+
+	private:
+		std::string parseImpl(Tag<std::string>);
+		char parseImpl(Tag<char>);
+		uint64_t parseImpl(Tag<uint64_t>);
+		int64_t parseImpl(Tag<int64_t>);
+		uint32_t parseImpl(Tag<uint32_t>);
+		int32_t parseImpl(Tag<int32_t>);
+		bool parseImpl(Tag<bool>);
+
+		bool testImpl(const std::string &expectedValue);
+		bool testImpl(char expectedValue);
+		bool testImpl(uint64_t expectedValue);
+		bool testImpl(int64_t expectedValue);
+		bool testImpl(uint32_t expectedValue);
+		bool testImpl(int32_t expectedValue);
+		bool testImpl(bool expectedValue);
+
+		uint64_t parseIntegerBody();
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+Parser<ParserPolicy>::Parser()
+:	Stream()
+{
+}
+
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+Parser<ParserPolicy>::Parser(std::string streamName, std::istream &istream)
+:	Stream(streamName, istream)
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+void Parser<ParserPolicy>::skipWhiteSpace()
+{
+	check();
+
+	while (!atEnd() && ParserPolicy::isWhiteSpaceCharacter(currentCharacter()))
+		advance();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+void Parser<ParserPolicy>::skipLine()
+{
+	check();
+
+	while (currentCharacter() != '\n')
+		advance();
+
+	advance();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+template<typename Type>
+Type Parser<ParserPolicy>::parse()
+{
+	return parseImpl(Tag<Type>());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+template<typename Type>
+bool Parser<ParserPolicy>::testAndReturn(const Type &expectedValue)
+{
+	const auto previousPosition = position();
+
+	const auto result = testImpl(expectedValue);
+
+	seek(previousPosition);
+
+	return result;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+template<typename Type>
+bool Parser<ParserPolicy>::testAndSkip(const Type &expectedValue)
+{
+	const auto previousPosition = position();
+
+	const auto result = testImpl(expectedValue);
+
+	if (result == false)
+		seek(previousPosition);
+
+	return result;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+template<typename Type>
+void Parser<ParserPolicy>::expect(const Type &expectedValue)
+{
+	if (testAndSkip(expectedValue))
+		return;
+
+	std::stringstream message;
+	message << "unexpected value, expected “" << expectedValue << "”";
+
+	throw ParserException(coordinate(), message.str());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+std::string Parser<ParserPolicy>::parseIdentifier()
+{
+	skipWhiteSpace();
+
+	std::string value;
+
+	while (true)
+	{
+		const auto character = currentCharacter();
+
+		if (!ParserPolicy::isIdentifierCharacter(character))
+			return value;
+
+		value.push_back(character);
+		advance();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testIdentifierAndSkip(const std::string &expectedValue)
+{
+	return testAndSkip(expectedValue) && !ParserPolicy::isIdentifierCharacter(currentCharacter());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::probeNumber()
+{
+	const auto previousPosition = position();
+
+	skipWhiteSpace();
+
+	while (!ParserPolicy::isWhiteSpaceCharacter(currentCharacter()))
+		if (!std::isdigit(currentCharacter()))
+		{
+			seek(previousPosition);
+
+			return false;
+		}
+
+	return true;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+std::string Parser<ParserPolicy>::parseLine()
+{
+	std::string value;
+
+	while (true)
+	{
+		const auto character = currentCharacter();
+		advance();
+
+		if (character == '\n')
+			break;
+		else if (character == '\r')
+			continue;
+
+		value.push_back(character);
+	}
+
+	return value;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+void Parser<ParserPolicy>::removeComments(const std::string &startSequence, const std::string &endSequence, bool removeEnd)
+{
+	const auto inPosition = m_stream.tellg();
+	const auto outPosition = m_stream.tellp();
+
+	m_stream.seekg(0);
+
+	const auto removeRange =
+		[&](const auto &start, const auto &end)
+		{
+			BOOST_ASSERT(start != -1);
+
+			m_stream.clear();
+			m_stream.seekp(start);
+			m_stream.seekg(start);
+
+			auto position = start;
+
+			while (end == -1 || position < end)
+			{
+				m_stream.ignore(1);
+
+				if (atEnd())
+					return;
+
+				m_stream.put(' ');
+				position += static_cast<std::streamoff>(1);
+			}
+		};
+
+	while (!atEnd())
+	{
+		Position startPosition = m_stream.tellg();
+
+		while (!atEnd())
+		{
+			startPosition = m_stream.tellg();
+
+			if (testAndSkip(startSequence))
+				break;
+
+			advance();
+		}
+
+		Position endPosition = m_stream.tellg();
+
+		while (!atEnd())
+		{
+			endPosition = m_stream.tellg();
+
+			if (testAndSkip(endSequence))
+				break;
+
+			advance();
+		}
+
+		if (removeEnd)
+			endPosition = m_stream.tellg();
+
+		removeRange(startPosition, endPosition);
+	}
+
+	m_stream.clear();
+
+	m_stream.seekg(inPosition);
+	m_stream.seekp(outPosition);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+char Parser<ParserPolicy>::currentCharacter() const
+{
+	return ParserPolicy::transformCharacter(Stream::currentCharacter());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+std::string Parser<ParserPolicy>::parseImpl(Tag<std::string>)
+{
+	skipWhiteSpace();
+
+	const auto startPosition = position();
+
+	while (!ParserPolicy::isWhiteSpaceCharacter(currentCharacter()))
+		advance();
+
+	const auto endPosition = position();
+	const auto length = static_cast<size_t>(endPosition - startPosition);
+
+	std::string value;
+	value.reserve(length);
+
+	seek(startPosition);
+
+	for (size_t i = 0; i < length; i++)
+	{
+		value.push_back(currentCharacter());
+		advance();
+	}
+
+	return value;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+char Parser<ParserPolicy>::parseImpl(Tag<char>)
+{
+	const auto value = currentCharacter();
+
+	advance();
+
+	return value;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+uint64_t Parser<ParserPolicy>::parseIntegerBody()
+{
+	check();
+
+	if (!std::isdigit(currentCharacter()))
+		throw ParserException(coordinate(), "could not parse integer value");
+
+	uint64_t value = 0;
+
+	while (!atEnd())
+	{
+		const auto character = currentCharacter();
+
+		if (!std::isdigit(character))
+			break;
+
+		value *= 10;
+		value += character - '0';
+
+		advance();
+	}
+
+	return value;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+int64_t Parser<ParserPolicy>::parseImpl(Tag<int64_t>)
+{
+	skipWhiteSpace();
+
+	bool positive = testAndSkip<char>('+') || !testAndSkip<char>('-');
+
+	const auto value = parseIntegerBody();
+
+	return (positive ? value : -value);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+uint64_t Parser<ParserPolicy>::parseImpl(Tag<uint64_t>)
+{
+	skipWhiteSpace();
+
+	if (currentCharacter() == '-')
+		throw ParserException(coordinate(), "expected unsigned integer, got signed one");
+
+	return parseIntegerBody();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+int32_t Parser<ParserPolicy>::parseImpl(Tag<int32_t>)
+{
+	return static_cast<int32_t>(parseImpl(Tag<int64_t>()));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+uint32_t Parser<ParserPolicy>::parseImpl(Tag<uint32_t>)
+{
+	return static_cast<uint32_t>(parseImpl(Tag<uint64_t>()));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::parseImpl(Tag<bool>)
+{
+	skipWhiteSpace();
+
+	if (testAndSkip<char>('0'))
+	    return false;
+
+	if (testAndSkip<char>('1'))
+		return true;
+
+	throw ParserException(coordinate(), "could not parse Boolean value");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testImpl(const std::string &expectedValue)
+{
+	if (!ParserPolicy::isWhiteSpaceCharacter(expectedValue.front()))
+		skipWhiteSpace();
+
+	const auto match = std::find_if(expectedValue.cbegin(), expectedValue.cend(),
+		[&](const auto &expectedCharacter)
+		{
+			const auto character = static_cast<char>(this->currentCharacter());
+
+			if (character != expectedCharacter)
+				return true;
+
+			this->advance();
+
+			return false;
+		});
+
+	return (match == expectedValue.cend());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testImpl(char expectedValue)
+{
+	const auto result = (currentCharacter() == expectedValue);
+
+	advance();
+
+	return result;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testImpl(int64_t expectedValue)
+{
+	const auto value = parseImpl(Tag<int64_t>());
+
+	return (value == expectedValue);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testImpl(uint64_t expectedValue)
+{
+	const auto value = parseImpl(Tag<uint64_t>());
+
+	return (value == expectedValue);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testImpl(int32_t expectedValue)
+{
+	return testImpl(static_cast<int64_t>(expectedValue));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testImpl(uint32_t expectedValue)
+{
+	return testImpl(static_cast<uint64_t>(expectedValue));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class ParserPolicy>
+bool Parser<ParserPolicy>::testImpl(bool expectedValue)
+{
+	const auto value = parseImpl(Tag<bool>());
+
+	return (value == expectedValue);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/utils/ParserException.h

@@ -4,6 +4,8 @@
 #include <exception>
 #include <string>
 
+#include <plasp/utils/StreamCoordinate.h>
+
 namespace plasp
 {
 namespace utils
@@ -18,17 +20,21 @@ namespace utils
 class ParserException: public std::exception
 {
 	public:
-		explicit ParserException()
+		explicit ParserException(const StreamCoordinate &coordinate)
+		:	ParserException(coordinate, "unspecified parser error")
 		{
 		}
 
-		explicit ParserException(const char *message)
-		:	m_message(message)
+		explicit ParserException(const StreamCoordinate &coordinate, const char *message)
+		:	ParserException(coordinate, static_cast<std::string>(message))
 		{
 		}
 
-		explicit ParserException(const std::string &message)
-		:	m_message(message)
+		explicit ParserException(const StreamCoordinate &coordinate, const std::string &message)
+		:	m_coordinate{coordinate},
+			m_message{message},
+			m_plainMessage{m_coordinate.sectionName + ":" + std::to_string(m_coordinate.row)
+				+ ":" + std::to_string(m_coordinate.column) + " " + m_message}
 		{
 		}
 
@@ -38,14 +44,23 @@ class ParserException: public std::exception
 
 		const char *what() const throw()
 		{
-			if (m_message.empty())
-				return "Unspecified error while parsing SAS description file";
+			return m_plainMessage.c_str();
+		}
 
-			return m_message.c_str();
+		const StreamCoordinate &coordinate() const
+		{
+			return m_coordinate;
+		}
+
+		const std::string &message() const
+		{
+			return m_message;
 		}
 
 	private:
+		StreamCoordinate m_coordinate;
 		std::string m_message;
+		std::string m_plainMessage;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////

include/plasp/utils/ParserPolicy.h

@@ -0,0 +1,62 @@
+#ifndef __PLASP__UTILS__PARSER_POLICY_H
+#define __PLASP__UTILS__PARSER_POLICY_H
+
+#include <iostream>
+
+namespace plasp
+{
+namespace utils
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ParserPolicy
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class CaseSensitiveParserPolicy
+{
+	public:
+		static constexpr char transformCharacter(char c) noexcept
+		{
+			return c;
+		}
+
+		static bool isWhiteSpaceCharacter(char c)
+		{
+			return std::iswspace(c);
+		}
+
+		static bool isIdentifierCharacter(char c)
+		{
+			return std::isgraph(c);
+		}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class CaseInsensitiveParserPolicy
+{
+	public:
+		static char transformCharacter(char c) noexcept
+		{
+			return std::tolower(c);
+		}
+
+		static bool isWhiteSpaceCharacter(char c)
+		{
+			return std::iswspace(c);
+		}
+
+		static bool isIdentifierCharacter(char c)
+		{
+			return std::isgraph(c);
+		}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/utils/Stream.h

@@ -0,0 +1,84 @@
+#ifndef __PLASP__UTILS__STREAM_H
+#define __PLASP__UTILS__STREAM_H
+
+#include <iostream>
+#include <iterator>
+#include <sstream>
+#include <vector>
+
+#include <boost/filesystem.hpp>
+
+#include <plasp/utils/ParserException.h>
+#include <plasp/utils/StreamCoordinate.h>
+
+namespace plasp
+{
+namespace utils
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Stream
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class Stream
+{
+	public:
+		using Position = std::stringstream::pos_type;
+
+		struct Delimiter
+		{
+			Position position;
+			std::string sectionName;
+		};
+
+	public:
+		explicit Stream();
+		explicit Stream(std::string streamName, std::istream &istream);
+
+		Stream(const Stream &other) = delete;
+		Stream &operator=(const Stream &other) = delete;
+
+		Stream(Stream &&other)
+		:	m_stream{std::move(other.m_stream)},
+			m_delimiters{std::move(other.m_delimiters)}
+		{
+		}
+
+		Stream &operator=(Stream &&other)
+		{
+			m_stream = std::move(other.m_stream);
+			m_delimiters = std::move(other.m_delimiters);
+
+			return *this;
+		}
+
+		~Stream() = default;
+
+		void read(std::string streamName, std::istream &istream);
+		void read(const boost::filesystem::path &path);
+
+		void reset();
+		void seek(Position position);
+		Position position() const;
+		StreamCoordinate coordinate() const;
+
+		char currentCharacter() const;
+		void advance();
+		bool atEnd() const;
+
+		void check() const;
+
+	protected:
+		mutable std::stringstream m_stream;
+
+		std::vector<Delimiter> m_delimiters;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/utils/StreamCoordinate.h

@@ -0,0 +1,29 @@
+#ifndef __PLASP__UTILS__STREAM_COORDINATE_H
+#define __PLASP__UTILS__STREAM_COORDINATE_H
+
+#include <string>
+
+namespace plasp
+{
+namespace utils
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// StreamCoordinate
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct StreamCoordinate
+{
+	std::string sectionName;
+	size_t row;
+	size_t column;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif

include/plasp/utils/TranslatorException.h

@@ -1,12 +1,12 @@
-#ifndef __PLASP__SAS__TRANSLATOR_EXCEPTION_H
-#define __PLASP__SAS__TRANSLATOR_EXCEPTION_H
+#ifndef __PLASP__UTILS__TRANSLATOR_EXCEPTION_H
+#define __PLASP__UTILS__TRANSLATOR_EXCEPTION_H
 
 #include <exception>
 #include <string>
 
 namespace plasp
 {
-namespace sas
+namespace utils
 {
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -39,7 +39,7 @@ class TranslatorException: public std::exception
 		const char *what() const throw()
 		{
 			if (m_message.empty())
-				return "Unspecified error while translating SAS description";
+				return "Unspecified error while translating description";
 
 			return m_message.c_str();
 		}

src/CMakeLists.txt

@@ -3,6 +3,12 @@ set(target plasp)
 file(GLOB core_sources "plasp/*.cpp")
 file(GLOB core_headers "../include/plasp/*.h")
 
+file(GLOB pddl_sources "plasp/pddl/*.cpp")
+file(GLOB pddl_headers "../include/plasp/pddl/*.h")
+
+file(GLOB pddl_expressions_sources "plasp/pddl/expressions/*.cpp")
+file(GLOB pddl_expressions_headers "../include/plasp/pddl/expressions/*.h")
+
 file(GLOB sas_sources "plasp/sas/*.cpp")
 file(GLOB sas_headers "../include/plasp/sas/*.h")
 
@@ -21,6 +27,12 @@ set(sources
 	${core_sources}
 	${core_headers}
 
+	${pddl_sources}
+	${pddl_headers}
+
+	${pddl_expressions_sources}
+	${pddl_expressions_headers}
+
 	${sas_sources}
 	${sas_headers}
 

src/plasp/Language.cpp

@@ -0,0 +1,50 @@
+#include <plasp/Language.h>
+
+#include <boost/assign.hpp>
+#include <boost/bimap.hpp>
+
+namespace plasp
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Language
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+using LanguageNames = boost::bimap<Language::Type, std::string>;
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const LanguageNames languageNames = boost::assign::list_of<LanguageNames::relation>
+	(Language::Type::PDDL, "pddl")
+	(Language::Type::SAS, "sas")
+	(Language::Type::Unknown, "unknown");
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+std::string Language::toString(Language::Type language)
+{
+	const auto match = languageNames.left.find(language);
+
+	if (match == languageNames.left.end())
+		return "unknown";
+
+	return match->second;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Language::Type Language::fromString(const std::string &languageName)
+{
+	const auto match = languageNames.right.find(languageName);
+
+	if (match == languageNames.right.end())
+		return Language::Type::Unknown;
+
+	return match->second;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}

src/plasp/pddl/Action.cpp

@@ -0,0 +1,92 @@
+#include <plasp/pddl/Action.h>
+
+#include <algorithm>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/expressions/Type.h>
+#include <plasp/utils/IO.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Action
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Action::parseDeclaration(Context &context, Domain &domain)
+{
+	auto &parser = context.parser;
+
+	auto action = std::make_unique<Action>(Action());
+
+	action->m_name = parser.parseIdentifier();
+
+	parser.expect<std::string>(":parameters");
+	parser.expect<std::string>("(");
+
+	ExpressionContext expressionContext(domain, action->m_parameters);
+
+	// Read parameters
+	expressions::Variable::parseTypedDeclarations(context, expressionContext);
+
+	parser.expect<std::string>(")");
+
+	// Parse preconditions and effects
+	while (!parser.testAndReturn(')'))
+	{
+		parser.expect<std::string>(":");
+
+		if (parser.testIdentifierAndSkip("precondition"))
+			action->m_precondition = parsePreconditionExpression(context, expressionContext);
+		else if (parser.testIdentifierAndSkip("effect"))
+			action->m_effect = parseEffectExpression(context, expressionContext);
+
+		parser.skipWhiteSpace();
+	}
+
+	// Store new action
+	expressionContext.domain.actions().emplace_back(std::move(action));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &Action::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const expressions::Variables &Action::parameters() const
+{
+	return m_parameters;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression *Action::precondition() const
+{
+	BOOST_ASSERT(m_precondition);
+
+	return m_precondition.get();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression *Action::effect() const
+{
+	BOOST_ASSERT(m_effect);
+
+	return m_effect.get();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/Description.cpp

@@ -0,0 +1,208 @@
+#include <plasp/pddl/Description.h>
+
+#include <fstream>
+#include <sstream>
+
+#include <boost/filesystem.hpp>
+
+#include <plasp/pddl/IO.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Description
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Description::Description()
+:	m_domainPosition{-1},
+	m_domain{std::make_unique<Domain>(Domain(m_context))},
+	m_problemPosition{-1}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Description Description::fromContext(Context &&context)
+{
+	Description description;
+
+	description.m_context = std::move(context);
+	description.parse();
+
+	return description;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Description Description::fromStream(std::istream &istream)
+{
+	Description description;
+
+	description.m_context.parser.read("std::cin", istream);
+	description.parse();
+
+	return description;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Description Description::fromFile(const std::string &path)
+{
+	Description description;
+
+	description.m_context.parser.read(path);
+	description.parse();
+
+	return description;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Description Description::fromFiles(const std::vector<std::string> &paths)
+{
+	BOOST_ASSERT(!paths.empty());
+
+	Description description;
+
+	std::for_each(paths.cbegin(), paths.cend(),
+		[&](const auto &path)
+		{
+			description.m_context.parser.read(path);
+		});
+
+	description.parse();
+
+	return description;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Context &Description::context()
+{
+	return m_context;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Context &Description::context() const
+{
+	return m_context;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Domain &Description::domain() const
+{
+	BOOST_ASSERT(m_domain);
+
+	return *m_domain;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool Description::containsProblem() const
+{
+	return m_problem.get() != nullptr;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Problem &Description::problem() const
+{
+	BOOST_ASSERT(m_problem);
+
+	return *m_problem;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Description::parse()
+{
+	auto &parser = m_context.parser;
+
+	parser.removeComments(";", "\n", false);
+
+	// First, determine the locations of domain and problem
+	findSections();
+
+	if (m_domainPosition == -1)
+		throw ConsistencyException("no PDDL domain specified");
+
+	parser.seek(m_domainPosition);
+	m_domain->parse();
+
+	if (m_problemPosition != -1)
+	{
+		parser.seek(m_problemPosition);
+		m_problem->parse();
+	}
+
+	checkConsistency();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Description::findSections()
+{
+	auto &parser = m_context.parser;
+
+	parser.skipWhiteSpace();
+
+	while (!parser.atEnd())
+	{
+		const auto position = parser.position();
+
+		parser.expect<std::string>("(");
+		parser.expect<std::string>("define");
+		parser.expect<std::string>("(");
+
+		if (parser.testAndSkip<std::string>("domain"))
+		{
+			if (m_domainPosition != -1)
+				throw utils::ParserException(parser.coordinate(), "PDDL description may not contain two domains");
+
+			m_domainPosition = position;
+
+			parser.seek(position);
+			m_domain->findSections();
+		}
+		else if (m_context.parser.testAndSkip<std::string>("problem"))
+		{
+			if (m_problemPosition != -1)
+				throw utils::ParserException(parser.coordinate(), "PDDL description may currently not contain two problems");
+
+			m_problem = std::make_unique<Problem>(Problem(m_context, *m_domain));
+
+			m_problemPosition = position;
+
+			parser.seek(position);
+			m_problem->findSections();
+		}
+		else
+		{
+			const auto sectionIdentifier = parser.parse<std::string>();
+			throw utils::ParserException(parser.coordinate(), "unknown PDDL section “" + sectionIdentifier + "”");
+		}
+
+		m_context.parser.skipWhiteSpace();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Description::checkConsistency()
+{
+	m_domain->checkConsistency();
+	m_problem->checkConsistency();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/Domain.cpp

@@ -0,0 +1,418 @@
+#include <plasp/pddl/Domain.h>
+
+#include <algorithm>
+
+#include <plasp/pddl/ConsistencyException.h>
+#include <plasp/pddl/IO.h>
+#include <plasp/pddl/expressions/Constant.h>
+#include <plasp/pddl/expressions/PredicateDeclaration.h>
+#include <plasp/pddl/expressions/PrimitiveType.h>
+#include <plasp/pddl/expressions/Variable.h>
+#include <plasp/utils/IO.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Domain
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Domain::Domain(Context &context)
+:	m_context(context),
+	m_requirementsPosition{-1},
+	m_typesPosition{-1},
+	m_constantsPosition{-1},
+	m_predicatesPosition{-1}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::findSections()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>("define");
+	parser.expect<std::string>("(");
+	parser.expect<std::string>("domain");
+
+	m_name = m_context.parser.parseIdentifier();
+
+	parser.expect<std::string>(")");
+
+	const auto setSectionPosition =
+		[&](const std::string &sectionName, auto &sectionPosition, const auto value, bool unique = false)
+		{
+			if (unique && sectionPosition != -1)
+			{
+				parser.seek(value);
+				throw utils::ParserException(parser.coordinate(), "only one “:" + sectionName + "” section allowed");
+			}
+
+			sectionPosition = value;
+		};
+
+	parser.skipWhiteSpace();
+
+	// Find sections
+	while (parser.currentCharacter() != ')')
+	{
+		const auto position = parser.position();
+
+		parser.expect<std::string>("(");
+		parser.expect<std::string>(":");
+
+		const auto sectionIdentifierPosition = parser.position();
+
+		// Save the parser position of the individual sections for later parsing
+		if (parser.testIdentifierAndSkip("requirements"))
+			setSectionPosition("requirements", m_requirementsPosition, position, true);
+		else if (parser.testIdentifierAndSkip("types"))
+			setSectionPosition("types", m_typesPosition, position, true);
+		else if (parser.testIdentifierAndSkip("constants"))
+			setSectionPosition("constants", m_constantsPosition, position, true);
+		else if (parser.testIdentifierAndSkip("predicates"))
+			setSectionPosition("predicates", m_predicatesPosition, position, true);
+		else if (parser.testIdentifierAndSkip("action"))
+		{
+			m_actionPositions.emplace_back(-1);
+			setSectionPosition("action", m_actionPositions.back(), position);
+		}
+		else if (parser.testIdentifierAndSkip("functions")
+			|| parser.testIdentifierAndSkip("constraints")
+			|| parser.testIdentifierAndSkip("durative-action")
+			|| parser.testIdentifierAndSkip("derived"))
+		{
+			parser.seek(sectionIdentifierPosition);
+
+			const auto sectionIdentifier = parser.parseIdentifier();
+
+			m_context.logger.logWarning(parser.coordinate(), "section type “" + sectionIdentifier + "” currently unsupported");
+
+			parser.seek(sectionIdentifierPosition);
+		}
+		else
+		{
+			const auto sectionIdentifier = parser.parseIdentifier();
+
+			parser.seek(position);
+			throw utils::ParserException(parser.coordinate(), "unknown domain section “" + sectionIdentifier + "”");
+		}
+
+		// Skip section for now and parse it later
+		skipSection(parser);
+
+		parser.skipWhiteSpace();
+	}
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::parse()
+{
+	auto &parser = m_context.parser;
+
+	if (m_requirementsPosition != -1)
+	{
+		parser.seek(m_requirementsPosition);
+		parseRequirementSection();
+	}
+
+	if (m_typesPosition != -1)
+	{
+		parser.seek(m_typesPosition);
+		parseTypeSection();
+	}
+
+	if (m_constantsPosition != -1)
+	{
+		parser.seek(m_constantsPosition);
+		parseConstantSection();
+	}
+
+	if (m_predicatesPosition != -1)
+	{
+		parser.seek(m_predicatesPosition);
+		parsePredicateSection();
+	}
+
+	for (size_t i = 0; i < m_actionPositions.size(); i++)
+		if (m_actionPositions[i] != -1)
+		{
+			parser.seek(m_actionPositions[i]);
+			parseActionSection();
+		}
+
+	computeDerivedRequirements();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::setName(std::string name)
+{
+	m_name = name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &Domain::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Requirements &Domain::requirements() const
+{
+	return m_requirements;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+expressions::PrimitiveTypes &Domain::types()
+{
+	return m_types;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const expressions::PrimitiveTypes &Domain::types() const
+{
+	return m_types;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+expressions::Constants &Domain::constants()
+{
+	return m_constants;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const expressions::Constants &Domain::constants() const
+{
+	return m_constants;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+expressions::PredicateDeclarations &Domain::predicates()
+{
+	return m_predicates;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const expressions::PredicateDeclarations &Domain::predicates() const
+{
+	return m_predicates;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+std::vector<std::unique_ptr<Action>> &Domain::actions()
+{
+	return m_actions;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::vector<std::unique_ptr<Action>> &Domain::actions() const
+{
+	return m_actions;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::parseRequirementSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("requirements");
+
+	while (parser.currentCharacter() != ')')
+	{
+		parser.expect<std::string>(":");
+
+		m_requirements.emplace_back(Requirement::parse(m_context));
+
+		parser.skipWhiteSpace();
+	}
+
+	// TODO: do this check only once the problem is parsed
+	// If no requirements are specified, assume STRIPS
+	if (m_requirements.empty())
+		m_requirements.emplace_back(Requirement::Type::STRIPS);
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool Domain::hasRequirement(Requirement::Type requirementType) const
+{
+	const auto match = std::find_if(m_requirements.cbegin(), m_requirements.cend(),
+		[&](const auto &requirement)
+		{
+			return requirement.type() == requirementType;
+		});
+
+	return match != m_requirements.cend();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::checkRequirement(Requirement::Type requirementType) const
+{
+	if (hasRequirement(requirementType))
+		return;
+
+	throw ConsistencyException("requirement “" + Requirement(requirementType).toPDDL() + "” used but never declared");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::computeDerivedRequirements()
+{
+	const auto addRequirementUnique =
+		[&](const auto requirement)
+		{
+			if (hasRequirement(requirement))
+				return;
+
+			m_requirements.push_back(Requirement(requirement));
+		};
+
+	if (hasRequirement(Requirement::Type::ADL))
+	{
+		addRequirementUnique(Requirement::Type::STRIPS);
+		addRequirementUnique(Requirement::Type::Typing);
+		addRequirementUnique(Requirement::Type::NegativePreconditions);
+		addRequirementUnique(Requirement::Type::DisjunctivePreconditions);
+		addRequirementUnique(Requirement::Type::Equality);
+		addRequirementUnique(Requirement::Type::QuantifiedPreconditions);
+		addRequirementUnique(Requirement::Type::ConditionalEffects);
+	}
+
+	if (hasRequirement(Requirement::Type::QuantifiedPreconditions))
+	{
+		addRequirementUnique(Requirement::Type::ExistentialPreconditions);
+		addRequirementUnique(Requirement::Type::UniversalPreconditions);
+	}
+
+	if (hasRequirement(Requirement::Type::Fluents))
+	{
+		addRequirementUnique(Requirement::Type::NumericFluents);
+		addRequirementUnique(Requirement::Type::ObjectFluents);
+	}
+
+	if (hasRequirement(Requirement::Type::TimedInitialLiterals))
+		addRequirementUnique(Requirement::Type::DurativeActions);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::parseTypeSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("types");
+
+	checkRequirement(Requirement::Type::Typing);
+
+	parser.skipWhiteSpace();
+
+	// Store types and their parent types
+	while (parser.currentCharacter() != ')')
+	{
+		if (parser.currentCharacter() == '(')
+			throw utils::ParserException(parser.coordinate(), "only primitive types are allowed in type section");
+
+		expressions::PrimitiveType::parseTypedDeclaration(m_context, *this);
+
+		parser.skipWhiteSpace();
+	}
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::parseConstantSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("constants");
+
+	// Store constants
+	expressions::Constant::parseTypedDeclarations(m_context, *this);
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::parsePredicateSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("predicates");
+
+	parser.skipWhiteSpace();
+
+	// Store predicates and their arguments
+	while (parser.currentCharacter() != ')')
+	{
+		expressions::PredicateDeclaration::parse(m_context, *this);
+
+		parser.skipWhiteSpace();
+	}
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::parseActionSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("action");
+
+	Action::parseDeclaration(m_context, *this);
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Domain::checkConsistency()
+{
+	// Verify that constants are unique
+	// Verify that all primitive types are unique
+	// Check for case-sensitivity issues
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/Expression.cpp

@@ -0,0 +1,254 @@
+#include <plasp/pddl/Expression.h>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/IO.h>
+#include <plasp/pddl/expressions/And.h>
+#include <plasp/pddl/expressions/Imply.h>
+#include <plasp/pddl/expressions/Not.h>
+#include <plasp/pddl/expressions/Or.h>
+#include <plasp/pddl/expressions/Predicate.h>
+#include <plasp/pddl/expressions/PredicateDeclaration.h>
+#include <plasp/pddl/expressions/Unsupported.h>
+#include <plasp/utils/IO.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Expression
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parseEffectBodyExpression(Context &context, ExpressionContext &expressionContext);
+ExpressionPointer parsePredicate(Context &context, ExpressionContext &expressionContext);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parsePreconditionExpression(Context &context,
+	ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	parser.skipWhiteSpace();
+
+	ExpressionPointer expression;
+
+	if ((expression = expressions::And::parse(context, expressionContext, parsePreconditionExpression)))
+		return expression;
+
+	const auto position = parser.position();
+
+	parser.expect<std::string>("(");
+
+	const auto expressionIdentifierPosition = parser.position();
+
+	if (parser.testIdentifierAndSkip("forall")
+		|| parser.testIdentifierAndSkip("preference"))
+	{
+		// TODO: refactor
+		parser.seek(expressionIdentifierPosition);
+		const auto expressionIdentifier = parser.parseIdentifier();
+
+		parser.seek(position);
+		return expressions::Unsupported::parse(context);
+	}
+
+	parser.seek(position);
+	return parseExpression(context, expressionContext);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parseExpression(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	parser.skipWhiteSpace();
+
+	ExpressionPointer expression;
+
+	if ((expression = expressions::And::parse(context, expressionContext, parseExpression))
+	    || (expression = expressions::Or::parse(context, expressionContext, parseExpression))
+		|| (expression = expressions::Not::parse(context, expressionContext, parseExpression))
+	    || (expression = expressions::Imply::parse(context, expressionContext, parseExpression))
+	    || (expression = expressions::Predicate::parse(context, expressionContext)))
+	{
+		return expression;
+	}
+
+	const auto position = parser.position();
+
+	parser.expect<std::string>("(");
+
+	const auto expressionIdentifierPosition = parser.position();
+
+	if (parser.testIdentifierAndSkip("exists")
+		|| parser.testIdentifierAndSkip("forall")
+		|| parser.testIdentifierAndSkip("-")
+		|| parser.testIdentifierAndSkip("=")
+		|| parser.testIdentifierAndSkip("*")
+		|| parser.testIdentifierAndSkip("+")
+		|| parser.testIdentifierAndSkip("-")
+		|| parser.testIdentifierAndSkip("/")
+		|| parser.testIdentifierAndSkip(">")
+		|| parser.testIdentifierAndSkip("<")
+		|| parser.testIdentifierAndSkip("=")
+		|| parser.testIdentifierAndSkip(">=")
+		|| parser.testIdentifierAndSkip("<="))
+	{
+		parser.seek(expressionIdentifierPosition);
+		const auto expressionIdentifier = parser.parseIdentifier();
+
+		parser.seek(position);
+		return expressions::Unsupported::parse(context);
+	}
+
+	parser.seek(expressionIdentifierPosition);
+	const auto expressionIdentifier = parser.parseIdentifier();
+
+	parser.seek(position);
+	throw utils::ParserException(parser.coordinate(), "expression type “" + expressionIdentifier + "” unknown or not allowed in this context");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parseEffectExpression(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	ExpressionPointer expression;
+
+	if ((expression = expressions::And::parse(context, expressionContext, parseEffectExpression)))
+		return expression;
+
+	const auto position = parser.position();
+
+	parser.expect<std::string>("(");
+
+	const auto expressionIdentifierPosition = parser.position();
+
+	if (parser.testIdentifierAndSkip("forall")
+		|| parser.testIdentifierAndSkip("when"))
+	{
+		parser.seek(expressionIdentifierPosition);
+		const auto expressionIdentifier = parser.parseIdentifier();
+
+		parser.seek(position);
+		return expressions::Unsupported::parse(context);
+	}
+
+	parser.seek(position);
+	return parseEffectBodyExpression(context, expressionContext);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parseEffectBodyExpression(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	ExpressionPointer expression;
+
+	if ((expression = expressions::Not::parse(context, expressionContext, parsePredicate))
+	    || (expression = expressions::Predicate::parse(context, expressionContext)))
+	{
+		return expression;
+	}
+
+	const auto position = parser.position();
+
+	parser.expect<std::string>("(");
+
+	const auto expressionIdentifierPosition = parser.position();
+
+	if (parser.testIdentifierAndSkip("=")
+		|| parser.testIdentifierAndSkip("assign")
+		|| parser.testIdentifierAndSkip("scale-up")
+		|| parser.testIdentifierAndSkip("scale-down")
+		|| parser.testIdentifierAndSkip("increase")
+		|| parser.testIdentifierAndSkip("decrease"))
+	{
+		parser.seek(expressionIdentifierPosition);
+		const auto expressionIdentifier = parser.parseIdentifier();
+
+		parser.seek(position);
+		return expressions::Unsupported::parse(context);
+	}
+
+	parser.seek(expressionIdentifierPosition);
+	const auto expressionIdentifier = parser.parseIdentifier();
+
+	parser.seek(position);
+	throw utils::ParserException(parser.coordinate(), "expression type “" + expressionIdentifier + "” unknown or not allowed in this context");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parsePredicate(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	ExpressionPointer expression;
+
+	if ((expression = expressions::Predicate::parse(context, expressionContext)))
+		return expression;
+
+	throw utils::ParserException(parser.coordinate(), "expected predicate");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parseLiteral(Context &context, ExpressionContext &expressionContext)
+{
+	ExpressionPointer expression;
+
+	if ((expression = parseAtomicFormula(context, expressionContext))
+		|| (expression = expressions::Not::parse(context, expressionContext, parseAtomicFormula)))
+	{
+		return expression;
+	}
+
+	return nullptr;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer parseAtomicFormula(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	ExpressionPointer expression;
+
+	if ((expression = expressions::Predicate::parse(context, expressionContext)))
+		return expression;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("("))
+		return nullptr;
+
+	const auto expressionIdentifierPosition = parser.position();
+
+	if (parser.testIdentifierAndSkip("="))
+	{
+		parser.seek(expressionIdentifierPosition);
+		const auto expressionIdentifier = parser.parseIdentifier();
+
+		parser.seek(position);
+		return expressions::Unsupported::parse(context);
+	}
+
+	parser.seek(position);
+	return nullptr;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/ExpressionContext.cpp

@@ -0,0 +1,56 @@
+#include <plasp/pddl/ExpressionContext.h>
+
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/Problem.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ExpressionContext
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionContext::ExpressionContext(Domain &domain, expressions::Variables &parameters)
+:	domain(domain),
+	problem(nullptr),
+	parameters(parameters)
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionContext::ExpressionContext(Domain &domain, Problem *problem, expressions::Variables &parameters)
+:	domain(domain),
+	problem{problem},
+	parameters(parameters)
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool ExpressionContext::hasRequirement(Requirement::Type requirementType) const
+{
+	if (problem != nullptr)
+		return problem->hasRequirement(requirementType);
+
+	return domain.hasRequirement(requirementType);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void ExpressionContext::checkRequirement(Requirement::Type requirementType) const
+{
+	if (problem != nullptr)
+		problem->checkRequirement(requirementType);
+	else
+		domain.checkRequirement(requirementType);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/InitialState.cpp

@@ -0,0 +1,89 @@
+#include <plasp/pddl/InitialState.h>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/IO.h>
+#include <plasp/pddl/Problem.h>
+#include <plasp/pddl/expressions/At.h>
+#include <plasp/pddl/expressions/Predicate.h>
+#include <plasp/pddl/expressions/Unsupported.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// InitialState
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+std::unique_ptr<InitialState> InitialState::parseDeclaration(Context &context,
+	ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	auto initialState = std::make_unique<InitialState>(InitialState());
+
+	const auto parseInitialStateElement =
+		[&]() -> ExpressionPointer
+		{
+			ExpressionPointer expression;
+
+			// TODO: do not allow negative initial state literals
+			if ((expression = parseLiteral(context, expressionContext))
+				|| (expression = expressions::At::parse(context, expressionContext, parseLiteral)))
+			{
+				return expression;
+			}
+
+			const auto position = parser.position();
+
+			parser.expect<std::string>("(");
+
+			const auto expressionIdentifierPosition = parser.position();
+
+			if (parser.testIdentifierAndSkip("="))
+			{
+				parser.seek(expressionIdentifierPosition);
+				const auto expressionIdentifier = parser.parseIdentifier();
+
+				parser.seek(position);
+				return expressions::Unsupported::parse(context);
+			}
+
+			parser.seek(expressionIdentifierPosition);
+			const auto expressionIdentifier = parser.parseIdentifier();
+
+			parser.seek(position);
+			throw utils::ParserException(parser.coordinate(), "expression type “" + expressionIdentifier + "” unknown or not allowed in this context");
+		};
+
+	parser.skipWhiteSpace();
+
+	while (parser.currentCharacter() != ')')
+	{
+		ExpressionPointer expression;
+
+		if ((expression = parseInitialStateElement()))
+			initialState->m_facts.emplace_back(std::move(expression));
+
+		parser.skipWhiteSpace();
+	}
+
+	return initialState;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expressions &InitialState::facts() const
+{
+	return m_facts;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/Problem.cpp

@@ -0,0 +1,398 @@
+#include <plasp/pddl/Problem.h>
+
+#include <algorithm>
+
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/IO.h>
+#include <plasp/pddl/expressions/Constant.h>
+#include <plasp/utils/IO.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Problem
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Problem::Problem(Context &context, Domain &domain)
+:	m_context(context),
+	m_domain(domain),
+	m_domainPosition{-1},
+	m_requirementsPosition{-1},
+	m_objectsPosition{-1},
+	m_initialStatePosition{-1},
+	m_goalPosition{-1}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::findSections()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>("define");
+	parser.expect<std::string>("(");
+	parser.expect<std::string>("problem");
+
+	m_name = parser.parseIdentifier();
+
+	parser.expect<std::string>(")");
+
+	const auto setSectionPosition =
+	[&](const std::string &sectionName, auto &sectionPosition, const auto value, bool unique = false)
+	{
+		if (unique && sectionPosition != -1)
+		{
+			parser.seek(value);
+			throw utils::ParserException(parser.coordinate(), "only one “:" + sectionName + "” section allowed");
+		}
+
+		sectionPosition = value;
+	};
+
+	parser.skipWhiteSpace();
+
+	while (parser.currentCharacter() != ')')
+	{
+		const auto position = parser.position();
+
+		parser.expect<std::string>("(");
+		parser.expect<std::string>(":");
+
+		const auto sectionIdentifierPosition = parser.position();
+
+		// TODO: check order of the sections
+		if (parser.testIdentifierAndSkip("domain"))
+			setSectionPosition("domain", m_domainPosition, position, true);
+		else if (parser.testIdentifierAndSkip("requirements"))
+			setSectionPosition("requirements", m_requirementsPosition, position, true);
+		else if (parser.testIdentifierAndSkip("objects"))
+			setSectionPosition("objects", m_objectsPosition, position, true);
+		else if (parser.testIdentifierAndSkip("init"))
+			setSectionPosition("init", m_initialStatePosition, position, true);
+		else if (parser.testIdentifierAndSkip("goal"))
+			setSectionPosition("goal", m_goalPosition, position, true);
+		else if (parser.testIdentifierAndSkip("constraints")
+			|| parser.testIdentifierAndSkip("metric")
+			|| parser.testIdentifierAndSkip("length"))
+		{
+			parser.seek(sectionIdentifierPosition);
+
+			const auto sectionIdentifier = parser.parseIdentifier();
+
+			m_context.logger.logWarning(parser.coordinate(), "section type “" + sectionIdentifier + "” currently unsupported");
+
+			parser.seek(sectionIdentifierPosition);
+		}
+		else
+		{
+			const auto sectionIdentifier = parser.parseIdentifier();
+
+			parser.seek(position);
+			throw utils::ParserException(parser.coordinate(), "unknown problem section “" + sectionIdentifier + "”");
+		}
+
+		// Skip section for now and parse it later
+		skipSection(parser);
+
+		parser.skipWhiteSpace();
+	}
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::parse()
+{
+	auto &parser = m_context.parser;
+
+	if (m_domainPosition == -1)
+		throw ConsistencyException("problem description does not specify the corresponding domain");
+
+	parser.seek(m_domainPosition);
+	parseDomainSection();
+
+	if (m_requirementsPosition != -1)
+	{
+		parser.seek(m_requirementsPosition);
+		parseRequirementSection();
+	}
+
+	if (m_objectsPosition != -1)
+	{
+		parser.seek(m_objectsPosition);
+		parseObjectSection();
+	}
+
+	if (m_initialStatePosition == -1)
+		throw ConsistencyException("problem description does not specify an initial state");
+
+	parser.seek(m_initialStatePosition);
+	parseInitialStateSection();
+
+	if (m_goalPosition == -1)
+		throw ConsistencyException("problem description does not specify a goal");
+
+	parser.seek(m_goalPosition);
+	parseGoalSection();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Domain &Problem::domain()
+{
+	return m_domain;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Domain &Problem::domain() const
+{
+	return m_domain;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &Problem::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Requirements &Problem::requirements() const
+{
+	return m_requirements;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+expressions::Constants &Problem::objects()
+{
+	return m_objects;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const expressions::Constants &Problem::objects() const
+{
+	return m_objects;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::parseDomainSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("domain");
+
+	parser.skipWhiteSpace();
+
+	const auto domainName = parser.parseIdentifier();
+
+	if (m_domain.name() != domainName)
+		throw utils::ParserException(parser.coordinate(), "domains do not match (“" + m_domain.name() + "” and “" + domainName + "”)");
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::parseRequirementSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("requirements");
+
+	parser.skipWhiteSpace();
+
+	while (parser.currentCharacter() != ')')
+	{
+		parser.expect<std::string>(":");
+
+		m_requirements.emplace_back(Requirement::parse(m_context));
+
+		parser.skipWhiteSpace();
+	}
+
+	// TODO: do this check only once the domain is parsed
+	// If no requirements are specified, assume STRIPS
+	if (m_requirements.empty())
+		m_requirements.emplace_back(Requirement::Type::STRIPS);
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool Problem::hasRequirement(Requirement::Type requirementType) const
+{
+	const auto match = std::find_if(m_requirements.cbegin(), m_requirements.cend(),
+		[&](const auto &requirement)
+		{
+			return requirement.type() == requirementType;
+		});
+
+	if (match != m_requirements.cend())
+		return true;
+
+	return m_domain.hasRequirement(requirementType);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::checkRequirement(Requirement::Type requirementType) const
+{
+	if (hasRequirement(requirementType))
+		return;
+
+	throw ConsistencyException("requirement “" + Requirement(requirementType).toPDDL() + "” used but never declared");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::computeDerivedRequirements()
+{
+	const auto addRequirementUnique =
+		[&](const auto requirement)
+		{
+			if (hasRequirement(requirement))
+				return;
+
+			m_requirements.push_back(Requirement(requirement));
+		};
+
+	if (hasRequirement(Requirement::Type::ADL))
+	{
+		addRequirementUnique(Requirement::Type::STRIPS);
+		addRequirementUnique(Requirement::Type::Typing);
+		addRequirementUnique(Requirement::Type::NegativePreconditions);
+		addRequirementUnique(Requirement::Type::DisjunctivePreconditions);
+		addRequirementUnique(Requirement::Type::Equality);
+		addRequirementUnique(Requirement::Type::QuantifiedPreconditions);
+		addRequirementUnique(Requirement::Type::ConditionalEffects);
+	}
+
+	if (hasRequirement(Requirement::Type::QuantifiedPreconditions))
+	{
+		addRequirementUnique(Requirement::Type::ExistentialPreconditions);
+		addRequirementUnique(Requirement::Type::UniversalPreconditions);
+	}
+
+	if (hasRequirement(Requirement::Type::Fluents))
+	{
+		addRequirementUnique(Requirement::Type::NumericFluents);
+		addRequirementUnique(Requirement::Type::ObjectFluents);
+	}
+
+	if (hasRequirement(Requirement::Type::TimedInitialLiterals))
+		addRequirementUnique(Requirement::Type::DurativeActions);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::parseObjectSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("objects");
+
+	parser.skipWhiteSpace();
+
+	// Store constants
+	expressions::Constant::parseTypedDeclarations(m_context, *this);
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::parseInitialStateSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("init");
+
+	// TODO: remove workaround
+	expressions::Variables noParameters;
+	ExpressionContext expressionContext(m_domain, this, noParameters);
+
+	m_initialState = InitialState::parseDeclaration(m_context, expressionContext);
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::parseGoalSection()
+{
+	auto &parser = m_context.parser;
+
+	parser.expect<std::string>("(");
+	parser.expect<std::string>(":");
+	parser.expect<std::string>("goal");
+
+	// TODO: remove workaround
+	expressions::Variables noParameters;
+	ExpressionContext expressionContext(m_domain, this, noParameters);
+
+	m_goal = parsePreconditionExpression(m_context, expressionContext);
+
+	parser.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+InitialState &Problem::initialState()
+{
+	BOOST_ASSERT(m_initialState);
+
+	return *m_initialState;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const InitialState &Problem::initialState() const
+{
+	BOOST_ASSERT(m_initialState);
+
+	return *m_initialState;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression &Problem::goal() const
+{
+	BOOST_ASSERT(m_goal);
+
+	return *m_goal;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Problem::checkConsistency()
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/Requirement.cpp

@@ -0,0 +1,135 @@
+#include <plasp/pddl/Requirement.h>
+
+#include <boost/assert.hpp>
+#include <boost/assign.hpp>
+#include <boost/bimap.hpp>
+
+#include <plasp/utils/IO.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Requirement
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+using RequirementTypeNames = boost::bimap<Requirement::Type, std::string>;
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const RequirementTypeNames requirementTypesToPDDL = boost::assign::list_of<RequirementTypeNames::relation>
+	(Requirement::Type::STRIPS, "strips")
+	(Requirement::Type::Typing, "typing")
+	(Requirement::Type::NegativePreconditions, "negative-preconditions")
+	(Requirement::Type::DisjunctivePreconditions, "disjunctive-preconditions")
+	(Requirement::Type::Equality, "equality")
+	(Requirement::Type::ExistentialPreconditions, "existential-preconditions")
+	(Requirement::Type::UniversalPreconditions, "universal-preconditions")
+	(Requirement::Type::QuantifiedPreconditions, "quantified-preconditions")
+	(Requirement::Type::ConditionalEffects, "conditional-effects")
+	(Requirement::Type::Fluents, "fluents")
+	(Requirement::Type::NumericFluents, "numeric-fluents")
+	(Requirement::Type::ObjectFluents, "object-fluents")
+	(Requirement::Type::ADL, "adl")
+	(Requirement::Type::DurativeActions, "durative-actions")
+	(Requirement::Type::DurationInequalities, "duration-inequalities")
+	(Requirement::Type::ContinuousEffects, "continuous-effects")
+	(Requirement::Type::DerivedPredicates, "derived-predicates")
+	(Requirement::Type::TimedInitialLiterals, "timed-initial-literals")
+	(Requirement::Type::Preferences, "preferences")
+	(Requirement::Type::Constraints, "constraints")
+	(Requirement::Type::ActionCosts, "action-costs")
+	(Requirement::Type::GoalUtilities, "goal-utilities");
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const RequirementTypeNames requirementTypesToASP = boost::assign::list_of<RequirementTypeNames::relation>
+	(Requirement::Type::STRIPS, "strips")
+	(Requirement::Type::Typing, "typing")
+	(Requirement::Type::NegativePreconditions, "negativePreconditions")
+	(Requirement::Type::DisjunctivePreconditions, "disjunctivePreconditions")
+	(Requirement::Type::Equality, "equality")
+	(Requirement::Type::ExistentialPreconditions, "existentialPreconditions")
+	(Requirement::Type::UniversalPreconditions, "universalPreconditions")
+	(Requirement::Type::QuantifiedPreconditions, "quantifiedPreconditions")
+	(Requirement::Type::ConditionalEffects, "conditionalEffects")
+	(Requirement::Type::Fluents, "fluents")
+	(Requirement::Type::NumericFluents, "numericFluents")
+	(Requirement::Type::ObjectFluents, "objectFluents")
+	(Requirement::Type::ADL, "adl")
+	(Requirement::Type::DurativeActions, "durativeActions")
+	(Requirement::Type::DurationInequalities, "durationInequalities")
+	(Requirement::Type::ContinuousEffects, "continuousEffects")
+	(Requirement::Type::DerivedPredicates, "derivedPredicates")
+	(Requirement::Type::TimedInitialLiterals, "timedInitialLiterals")
+	(Requirement::Type::Preferences, "preferences")
+	(Requirement::Type::Constraints, "constraints")
+	(Requirement::Type::ActionCosts, "actionCosts")
+	(Requirement::Type::GoalUtilities, "goalUtilities");
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Requirement::Requirement(Requirement::Type type)
+:	m_type{type}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Requirement Requirement::parse(Context &context)
+{
+	auto &parser = context.parser;
+
+	const auto requirementName = parser.parseIdentifier();
+
+	const auto match = requirementTypesToPDDL.right.find(requirementName);
+
+	if (match == requirementTypesToPDDL.right.end())
+		throw utils::ParserException(parser.coordinate(), "unknown PDDL requirement “" + requirementName + "”");
+
+	const auto requirementType = match->second;
+
+	if (requirementType == Requirement::Type::GoalUtilities)
+		context.logger.logWarning(parser.coordinate(), "requirement “goal-utilities” is not part of the PDDL 3.1 specification");
+
+	return Requirement(match->second);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Requirement::Type Requirement::type() const
+{
+	return m_type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+std::string Requirement::toPDDL() const
+{
+	const auto match = requirementTypesToPDDL.left.find(m_type);
+
+	BOOST_ASSERT(match != requirementTypesToPDDL.left.end());
+
+	return match->second;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+std::string Requirement::toASP() const
+{
+	const auto match = requirementTypesToASP.left.find(m_type);
+
+	BOOST_ASSERT(match != requirementTypesToASP.left.end());
+
+	return match->second;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/TranslatorASP.cpp

@@ -0,0 +1,568 @@
+#include <plasp/pddl/TranslatorASP.h>
+
+#include <boost/assert.hpp>
+
+#include <plasp/pddl/expressions/And.h>
+#include <plasp/pddl/expressions/Not.h>
+#include <plasp/pddl/expressions/Predicate.h>
+#include <plasp/utils/Formatting.h>
+#include <plasp/utils/IO.h>
+#include <plasp/utils/TranslatorException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// TranslatorASP
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+TranslatorASP::TranslatorASP(const Description &description, utils::LogStream &outputStream)
+:	m_description(description),
+	m_outputStream(outputStream)
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translate() const
+{
+	translateDomain();
+
+	if (m_description.containsProblem())
+	{
+		m_outputStream << std::endl;
+		translateProblem();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateDomain() const
+{
+	m_outputStream << utils::Heading1("domain");
+
+	const auto &domain = m_description.domain();
+
+	// Types
+	m_outputStream << std::endl;
+	translateTypes();
+
+	// Constants
+	if (!domain.constants().empty())
+	{
+		m_outputStream << std::endl;
+		translateConstants("constants", domain.constants());
+	}
+
+	// Predicates
+	if (!domain.predicates().empty())
+	{
+		m_outputStream << std::endl;
+		translatePredicates();
+	}
+
+	// Actions
+	if (!domain.actions().empty())
+	{
+		m_outputStream << std::endl;
+		translateActions();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateTypes() const
+{
+	m_outputStream << utils::Heading2("types");
+
+	m_outputStream << std::endl;
+
+	const auto &types = m_description.domain().types();
+
+	if (types.empty())
+	{
+		m_outputStream
+			<< utils::Keyword("type") << "("
+			<< utils::Keyword("type") << "(object))." << std::endl;
+
+		return;
+	}
+
+	std::for_each(types.cbegin(), types.cend(),
+		[&](const auto &type)
+		{
+			const auto typeName = utils::escapeASP(type->name());
+
+			m_outputStream
+				<< utils::Keyword("type") << "("
+				<< utils::Keyword("type") << "("
+				<< typeName << "))." << std::endl;
+
+			const auto &parentTypes = type->parentTypes();
+
+			std::for_each(parentTypes.cbegin(), parentTypes.cend(),
+				[&](const auto &parentType)
+				{
+					const auto parentTypeName = utils::escapeASP(parentType->name());
+
+					m_outputStream
+						<< utils::Keyword("inherits") << "(" << utils::Keyword("type")
+						<< "(" << typeName << "), " << utils::Keyword("type")
+						<< "(" << parentTypeName << "))." << std::endl
+
+						<< utils::Keyword("has") << "(" << utils::Variable("X") << ", "
+						<< utils::Keyword("type") << "(" << parentTypeName << ")) :- "
+						<< utils::Keyword("has") << "(" << utils::Variable("X") << ", "
+						<< utils::Keyword("type") << "(" << typeName << "))." << std::endl;
+				});
+		});
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translatePredicates() const
+{
+	m_outputStream << utils::Heading2("variables");
+
+	const auto &predicates = m_description.domain().predicates();
+
+	const auto printPredicateName =
+		[&](const auto &predicate)
+		{
+			m_outputStream
+				<< utils::escapeASP(predicate->name());
+
+			this->translateVariablesHead(predicate->arguments());
+		};
+
+	const auto printValueRule =
+		[&](const auto &predicate, const auto &value)
+		{
+			m_outputStream
+				<< utils::Keyword("contains") << "("
+				<< utils::Keyword("variable") << "(";
+
+			printPredicateName(predicate);
+
+			m_outputStream
+				<< "), " << utils::Keyword("value") << "(";
+
+			printPredicateName(predicate);
+
+			m_outputStream << ", " << utils::Keyword(value) << "))";
+
+			this->translateVariablesBody(predicate->arguments());
+
+			m_outputStream << "." << std::endl;
+		};
+
+	std::for_each(predicates.cbegin(), predicates.cend(),
+		[&](const auto &predicate)
+		{
+			m_outputStream
+				<< std::endl
+				<< utils::Keyword("variable") << "("
+				<< utils::Keyword("variable") << "(";
+
+			printPredicateName(predicate);
+
+			m_outputStream << "))";
+
+			this->translateVariablesBody(predicate->arguments());
+
+			m_outputStream << "." << std::endl;
+
+			printValueRule(predicate, "true");
+			printValueRule(predicate, "false");
+		});
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateActions() const
+{
+	m_outputStream << utils::Heading2("actions");
+
+	const auto &actions = m_description.domain().actions();
+
+	const auto printActionName =
+		[&](const auto &action)
+		{
+			m_outputStream << utils::Keyword("action") << "(" << utils::escapeASP(action.name());
+
+			this->translateVariablesHead(action.parameters());
+
+			m_outputStream << ")";
+		};
+
+	std::for_each(actions.cbegin(), actions.cend(),
+		[&](const auto &action)
+		{
+			// TODO: rename
+			const auto translateLiteral =
+				[&](const auto &ruleHead, const auto &literal, bool enumerateEffects = false)
+				{
+					m_outputStream << std::endl << utils::Keyword(ruleHead) << "(";
+
+					printActionName(*action);
+
+					// TODO: implement conditional effects
+					if (enumerateEffects)
+						m_outputStream << ", " << utils::Keyword("effect") << "(unconditional)";
+
+					m_outputStream << ", ";
+
+					this->translateLiteral(literal);
+
+					m_outputStream << ") :- " << utils::Keyword("action") << "(";
+
+					printActionName(*action);
+
+					m_outputStream << ").";
+				};
+
+			m_outputStream << std::endl;
+
+			// Name
+			m_outputStream << utils::Keyword("action") << "(";
+			printActionName(*action);
+			m_outputStream << ")";
+
+			this->translateVariablesBody(action->parameters());
+
+			m_outputStream << ".";
+
+			// Precondition
+			if (action->precondition())
+			{
+				const auto &precondition = *action->precondition();
+
+				if (precondition.expressionType() == Expression::Type::Predicate
+					|| precondition.expressionType() == Expression::Type::Not)
+				{
+					translateLiteral("precondition", precondition);
+				}
+				// Assuming a conjunction
+				else
+				{
+					if (precondition.expressionType() != Expression::Type::And)
+						throw utils::TranslatorException("only “and” expressions and (negated) predicates supported as action preconditions currently");
+
+					const auto &andExpression = dynamic_cast<const expressions::And &>(precondition);
+
+					std::for_each(andExpression.arguments().cbegin(), andExpression.arguments().cend(),
+						[&](const auto *argument)
+						{
+							translateLiteral("precondition", *argument);
+						});
+				}
+			}
+
+			// Effect
+			if (action->effect())
+			{
+				const auto &effect = *action->effect();
+
+				if (effect.expressionType() == Expression::Type::Predicate
+					|| effect.expressionType() == Expression::Type::Not)
+				{
+					translateLiteral("postcondition", effect, true);
+				}
+				// Assuming a conjunction
+				else
+				{
+					if (effect.expressionType() != Expression::Type::And)
+						throw utils::TranslatorException("only “and” expressions and (negated) predicates supported as action effects currently");
+
+					const auto &andExpression = dynamic_cast<const expressions::And &>(effect);
+
+					std::for_each(andExpression.arguments().cbegin(), andExpression.arguments().cend(),
+						[&](const auto *argument)
+						{
+							translateLiteral("postcondition", *argument, true);
+						});
+				}
+			}
+
+			m_outputStream << std::endl;
+		});
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateConstants(const std::string &heading, const expressions::Constants &constants) const
+{
+	m_outputStream << utils::Heading2(heading);
+
+	std::for_each(constants.cbegin(), constants.cend(),
+		[&](const auto &constant)
+		{
+			const auto constantName = utils::escapeASP(constant->name());
+
+			m_outputStream << std::endl
+				<< utils::Keyword("constant") << "("
+				<< utils::Keyword("constant") << "("
+				<< constantName
+				<< "))." << std::endl;
+
+			const auto *type = constant->type();
+
+			if (type != nullptr)
+			{
+				m_outputStream << utils::Keyword("has") << "("
+					<< utils::Keyword("constant") << "(" << constantName << "), "
+					<< utils::Keyword("type") << "(" << utils::escapeASP(type->name()) << "))." << std::endl;
+			}
+			else
+			{
+				m_outputStream << utils::Keyword("has") << "("
+					<< utils::Keyword("constant") << "(" << constantName << "), "
+					<< utils::Keyword("type") << "(object))." << std::endl;
+			}
+		});
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateVariablesHead(const expressions::Variables &variables) const
+{
+	if (variables.empty())
+		return;
+
+	m_outputStream << "(";
+
+	for (auto i = variables.cbegin(); i != variables.cend(); i++)
+	{
+		if (i != variables.cbegin())
+			m_outputStream << ", ";
+
+		const auto &variable = **i;
+
+		m_outputStream << utils::Variable(utils::escapeASPVariable(variable.name()));
+	}
+
+	m_outputStream << ")";
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateVariablesBody(const expressions::Variables &variables) const
+{
+	if (variables.empty())
+		return;
+
+	m_outputStream << " :- ";
+
+	for (auto i = variables.cbegin(); i != variables.cend(); i++)
+	{
+		const auto &variable = **i;
+
+		if (i != variables.cbegin())
+			m_outputStream << ", ";
+
+		if (variable.type() != nullptr)
+		{
+			if (variable.type()->expressionType() != Expression::Type::PrimitiveType)
+				throw utils::TranslatorException("only primitive types supported currently");
+
+			const auto &type = *dynamic_cast<const expressions::PrimitiveType *>(variable.type());
+
+			m_outputStream << utils::Keyword("has") << "("
+				<< utils::Variable(utils::escapeASPVariable(variable.name())) << ", "
+				<< utils::Keyword("type") << "(" << utils::escapeASP(type.name()) << "))";
+		}
+		else
+		{
+			m_outputStream << utils::Keyword("has") << "("
+				<< utils::Variable(utils::escapeASPVariable(variable.name())) << ", "
+				<< utils::Keyword("type") << "(object))";
+		}
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateLiteral(const Expression &literal) const
+{
+	// Translate single predicate
+	if (literal.expressionType() == Expression::Type::Predicate)
+	{
+		const auto &predicate = dynamic_cast<const expressions::Predicate &>(literal);
+
+		m_outputStream << utils::Keyword("variable") << "(";
+		this->translatePredicate(predicate);
+		m_outputStream << "), " << utils::Keyword("value") << "(";
+		this->translatePredicate(predicate);
+		m_outputStream << ", " << utils::Keyword("true") << ")";
+	}
+	// Assuming that "not" expression may only contain a predicate
+	else if (literal.expressionType() == Expression::Type::Not)
+	{
+		const auto &notExpression = dynamic_cast<const expressions::Not &>(literal);
+		const auto &predicate = dynamic_cast<const expressions::Predicate &>(*notExpression.argument());
+
+		m_outputStream << utils::Keyword("variable") << "(";
+		this->translatePredicate(predicate);
+		m_outputStream << "), " << utils::Keyword("value") << "(";
+		this->translatePredicate(predicate);
+		m_outputStream << ", " << utils::Keyword("false") << ")";
+	}
+	else
+		throw utils::TranslatorException("only primitive predicates and their negations supported as literals currently");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translatePredicate(const expressions::Predicate &predicate) const
+{
+	m_outputStream << utils::escapeASP(predicate.name());
+
+	const auto &arguments = predicate.arguments();
+
+	if (arguments.empty())
+	{
+		return;
+	}
+
+	m_outputStream << "(";
+
+	for (auto i = arguments.cbegin(); i != arguments.cend(); i++)
+	{
+		if (i != arguments.cbegin())
+			m_outputStream << ", ";
+
+		if ((*i)->expressionType() == Expression::Type::Constant)
+		{
+			const auto &constant = dynamic_cast<const expressions::Constant &>(**i);
+
+			m_outputStream << utils::Keyword("constant") << "(" << utils::escapeASP(constant.name()) << ")";
+		}
+		else if ((*i)->expressionType() == Expression::Type::Variable)
+		{
+			const auto &variable = dynamic_cast<const expressions::Variable &>(**i);
+
+			m_outputStream << utils::Variable(utils::escapeASPVariable(variable.name()));
+		}
+		else
+			throw utils::TranslatorException("only variables and constants supported in predicates currently");
+	}
+
+	m_outputStream << ")";
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateProblem() const
+{
+	BOOST_ASSERT(m_description.containsProblem());
+
+	m_outputStream << utils::Heading1("problem");
+
+	const auto &problem = m_description.problem();
+
+	// Objects
+	if (!problem.objects().empty())
+	{
+		m_outputStream << std::endl;
+		translateConstants("objects", problem.objects());
+	}
+
+	// Initial State
+	m_outputStream << std::endl;
+	translateInitialState();
+
+	// Goal
+	m_outputStream << std::endl;
+	translateGoal();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateInitialState() const
+{
+	BOOST_ASSERT(m_description.containsProblem());
+
+	m_outputStream << utils::Heading2("initial state");
+
+	const auto &initialStateFacts = m_description.problem().initialState().facts();
+
+	std::for_each(initialStateFacts.cbegin(), initialStateFacts.cend(),
+		[&](const auto &fact)
+		{
+			m_outputStream << std::endl << utils::Keyword("initialState") << "(";
+
+			// Translate single predicate
+			if (fact->expressionType() == Expression::Type::Predicate)
+			{
+				const auto &predicate = dynamic_cast<const expressions::Predicate &>(*fact);
+
+				m_outputStream << utils::Keyword("variable") << "(";
+				this->translatePredicate(predicate);
+				m_outputStream << "), " << utils::Keyword("value") << "(";
+				this->translatePredicate(predicate);
+				m_outputStream << ", " << utils::Keyword("true") << ")";
+			}
+			// Assuming that "not" expression may only contain a predicate
+			else if (fact->expressionType() == Expression::Type::Not)
+			{
+				const auto &notExpression = dynamic_cast<const expressions::Not &>(*fact);
+
+				if (notExpression.argument()->expressionType() != Expression::Type::Predicate)
+					throw utils::TranslatorException("only negations of simple predicates supported in initial state currently");
+			}
+			else
+				throw utils::TranslatorException("only predicates and their negations supported in initial state currently");
+
+			m_outputStream << ").";
+		});
+
+	m_outputStream << std::endl;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void TranslatorASP::translateGoal() const
+{
+	BOOST_ASSERT(m_description.containsProblem());
+
+	m_outputStream << utils::Heading2("goal");
+
+	const auto &goal = m_description.problem().goal();
+
+	if (goal.expressionType() == Expression::Type::Predicate
+		|| goal.expressionType() == Expression::Type::Not)
+	{
+		m_outputStream << std::endl << utils::Keyword("goal") << "(";
+
+		translateLiteral(goal);
+
+		m_outputStream << ").";
+	}
+	else if (goal.expressionType() == Expression::Type::And)
+	{
+		const auto &andExpression = dynamic_cast<const expressions::And &>(goal);
+
+		std::for_each(andExpression.arguments().cbegin(), andExpression.arguments().cend(),
+			[&](const auto *argument)
+			{
+				m_outputStream << std::endl << utils::Keyword("goal") << "(";
+
+				this->translateLiteral(*argument);
+
+				m_outputStream << ").";
+			});
+	}
+	else
+		throw utils::TranslatorException("only single predicates, their negations, and conjunctions are currently supported in the goal");
+
+	m_outputStream << std::endl;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}

src/plasp/pddl/expressions/And.cpp

@@ -0,0 +1,22 @@
+#include <plasp/pddl/expressions/And.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// And
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string And::Identifier = "and";
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/At.cpp

@@ -0,0 +1,48 @@
+#include <plasp/pddl/expressions/At.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// At
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+At::At()
+:	m_argument{nullptr}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void At::setArgument(const Expression *argument)
+{
+	m_argumentStorage = nullptr;
+	m_argument = argument;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void At::setArgument(ExpressionPointer &&argument)
+{
+	m_argumentStorage = std::move(argument);
+	m_argument = m_argumentStorage.get();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression *At::argument() const
+{
+	return m_argument;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Constant.cpp

@@ -0,0 +1,244 @@
+#include <plasp/pddl/expressions/Constant.h>
+
+#include <algorithm>
+
+#include <boost/assert.hpp>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/Problem.h>
+#include <plasp/pddl/expressions/PrimitiveType.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Constant
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Constant::Constant()
+:	m_isDirty{false},
+	m_type{nullptr}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ConstantPointer Constant::parseDeclaration(Context &context)
+{
+	context.parser.skipWhiteSpace();
+
+	auto constant = std::make_unique<Constant>(Constant());
+
+	constant->m_name = context.parser.parseIdentifier();
+
+	BOOST_ASSERT(constant->m_name != "-");
+
+	// Flag constant for potentially upcoming type declaration
+	constant->setDirty();
+
+	return constant;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Constant::parseTypedDeclaration(Context &context, Domain &domain)
+{
+	parseTypedDeclaration(context, domain, domain.constants());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Constant::parseTypedDeclaration(Context &context, Problem &problem)
+{
+	parseTypedDeclaration(context, problem.domain(), problem.objects());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Constant::parseTypedDeclaration(Context &context, Domain &domain, Constants &constants)
+{
+	// Parse and store constant
+	constants.emplace_back(parseDeclaration(context));
+
+	context.parser.skipWhiteSpace();
+
+	// Check for typing information
+	if (!context.parser.testAndSkip<char>('-'))
+		return;
+
+	// If existing, parse and store parent type
+	auto *type = PrimitiveType::parseAndFind(context, domain);
+
+	// Assign parent type to all types that were previously flagged
+	std::for_each(constants.begin(), constants.end(),
+		[&](auto &constant)
+		{
+			if (!constant->isDirty())
+				return;
+
+			constant->setType(type);
+			constant->setDirty(false);
+		});
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Constant::parseTypedDeclarations(Context &context, Domain &domain)
+{
+	auto &parser = context.parser;
+
+	while (parser.currentCharacter() != ')')
+	{
+		parseTypedDeclaration(context, domain);
+
+		parser.skipWhiteSpace();
+	}
+
+	if (domain.constants().empty())
+		return;
+
+	// Check correct use of typing requirement
+	const auto typingUsed = (domain.constants().back()->type() != nullptr);
+
+	// If types are given, check that typing is a requirement
+	if (typingUsed)
+		domain.checkRequirement(Requirement::Type::Typing);
+	// If no types are given, check that typing is not a requirement
+	else if (domain.hasRequirement(Requirement::Type::Typing))
+		throw utils::ParserException(parser.coordinate(), "constant has undeclared type");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Constant::parseTypedDeclarations(Context &context, Problem &problem)
+{
+	auto &parser = context.parser;
+
+	while (context.parser.currentCharacter() != ')')
+	{
+		parseTypedDeclaration(context, problem);
+
+		parser.skipWhiteSpace();
+	}
+
+	if (problem.objects().empty())
+		return;
+
+	// Check correct use of typing requirement
+	const auto typingUsed = (problem.objects().back()->type() != nullptr);
+
+	// If types are given, check that typing is a requirement
+	if (typingUsed)
+		problem.checkRequirement(Requirement::Type::Typing);
+	// If no types are given, check that typing is not a requirement
+	else if (problem.hasRequirement(Requirement::Type::Typing))
+		throw utils::ParserException(parser.coordinate(), "constant has undeclared type");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Constant *Constant::parseAndFind(Context &context, const Domain &domain)
+{
+	auto &parser = context.parser;
+
+	parser.skipWhiteSpace();
+
+	const auto constantName = parser.parseIdentifier();
+
+	auto *constant = parseAndFind(constantName, domain.constants());
+
+	if (constant != nullptr)
+		return constant;
+
+	throw utils::ParserException(parser.coordinate(), "constant “" + constantName + "” used but never declared");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Constant *Constant::parseAndFind(Context &context, const Problem &problem)
+{
+	auto &parser = context.parser;
+
+	parser.skipWhiteSpace();
+
+	const auto constantName = parser.parseIdentifier();
+
+	auto *constant = parseAndFind(constantName, problem.domain().constants());
+
+	if (constant)
+		return constant;
+
+	constant = parseAndFind(constantName, problem.objects());
+
+	if (constant)
+		return constant;
+
+	throw utils::ParserException(parser.coordinate(), "constant “" + constantName + "” used but never declared");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Constant *Constant::parseAndFind(const std::string &constantName, const Constants &constants)
+{
+	const auto match = std::find_if(constants.cbegin(), constants.cend(),
+		[&](const auto &constant)
+		{
+			return constant->name() == constantName;
+		});
+
+	const auto constantExists = (match != constants.cend());
+
+	if (!constantExists)
+		return nullptr;
+
+	return match->get();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Constant::setDirty(bool isDirty)
+{
+	m_isDirty = isDirty;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool Constant::isDirty() const
+{
+	return m_isDirty;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &Constant::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Constant::setType(const PrimitiveType *type)
+{
+	m_type = type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const PrimitiveType *Constant::type() const
+{
+	return m_type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Either.cpp

@@ -0,0 +1,22 @@
+#include <plasp/pddl/expressions/Either.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Either
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string Either::Identifier = "either";
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Imply.cpp

@@ -0,0 +1,23 @@
+#include <plasp/pddl/expressions/Imply.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Imply
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+// TODO: make static character string literal
+const std::string Imply::Identifier = "imply";
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Not.cpp

@@ -0,0 +1,48 @@
+#include <plasp/pddl/expressions/Not.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Not
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Not::Not()
+:	m_argument{nullptr}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Not::setArgument(const Expression *argument)
+{
+	m_argumentStorage = nullptr;
+	m_argument = argument;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Not::setArgument(ExpressionPointer &&argument)
+{
+	m_argumentStorage = std::move(argument);
+	m_argument = m_argumentStorage.get();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression *Not::argument() const
+{
+	return m_argument;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Or.cpp

@@ -0,0 +1,22 @@
+#include <plasp/pddl/expressions/Or.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Or
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string Or::Identifier = "or";
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Predicate.cpp

@@ -0,0 +1,175 @@
+#include <plasp/pddl/expressions/Predicate.h>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/Problem.h>
+#include <plasp/pddl/expressions/Constant.h>
+#include <plasp/pddl/expressions/Variable.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Predicate
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Predicate::Predicate()
+:	m_isDeclared{false}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+PredicatePointer Predicate::parse(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("("))
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	const auto predicateName = parser.parseIdentifier();
+	const auto &predicates = expressionContext.domain.predicates();
+
+	const auto matchingPredicate = std::find_if(predicates.cbegin(), predicates.cend(),
+		[&](const auto &predicate)
+		{
+			return predicate->name() == predicateName;
+		});
+
+	if (matchingPredicate == predicates.cend())
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	auto predicate = std::make_unique<Predicate>(Predicate());
+
+	predicate->m_name = predicateName;
+
+	context.parser.skipWhiteSpace();
+
+	// Parse arguments
+	while (context.parser.currentCharacter() != ')')
+	{
+		// Parse variables
+		if (context.parser.currentCharacter() == '?')
+		{
+			const auto *variable = Variable::parseAndFind(context, expressionContext);
+			predicate->m_arguments.emplace_back(variable);
+		}
+		// Parse constants
+		else
+		{
+			const auto *constant = (expressionContext.problem == nullptr)
+				? Constant::parseAndFind(context, expressionContext.domain)
+				: Constant::parseAndFind(context, *expressionContext.problem);
+			predicate->m_arguments.emplace_back(constant);
+		}
+
+		context.parser.skipWhiteSpace();
+	}
+
+	// TODO: check that signature matches one of the declared ones
+
+	parser.expect<std::string>(")");
+
+	return predicate;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+PredicatePointer Predicate::parse(Context &context, const Problem &problem)
+{
+	auto &parser = context.parser;
+
+	const auto position = parser.position();
+
+	if (!parser.testAndSkip<std::string>("("))
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	const auto predicateName = parser.parseIdentifier();
+	const auto &predicates = problem.domain().predicates();
+
+	const auto matchingPredicate = std::find_if(predicates.cbegin(), predicates.cend(),
+		[&](const auto &predicate)
+		{
+			return predicate->name() == predicateName;
+		});
+
+	if (matchingPredicate == predicates.cend())
+	{
+		parser.seek(position);
+		return nullptr;
+	}
+
+	auto predicate = std::make_unique<Predicate>(Predicate());
+
+	predicate->m_name = predicateName;
+
+	parser.skipWhiteSpace();
+
+	while (parser.currentCharacter() != ')')
+	{
+		if (parser.currentCharacter() == '?')
+			throw utils::ParserException(parser.coordinate(), "variables not allowed in this context");
+
+		// Parse objects and constants
+		const auto *constant = Constant::parseAndFind(context, problem);
+		predicate->m_arguments.emplace_back(constant);
+	}
+
+	// TODO: check that signature matches one of the declared ones
+
+	parser.expect<std::string>(")");
+
+	return predicate;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Predicate::setDeclared()
+{
+	m_isDeclared = true;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool Predicate::isDeclared() const
+{
+	return m_isDeclared;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &Predicate::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::vector<const Expression *> &Predicate::arguments() const
+{
+	return m_arguments;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/PredicateDeclaration.cpp

@@ -0,0 +1,84 @@
+#include <plasp/pddl/expressions/PredicateDeclaration.h>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/expressions/Constant.h>
+#include <plasp/pddl/expressions/Variable.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PredicateDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+PredicateDeclaration::PredicateDeclaration()
+:	m_isDeclared{false}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void PredicateDeclaration::parse(Context &context, Domain &domain)
+{
+	context.parser.expect<std::string>("(");
+
+	auto predicate = std::make_unique<PredicateDeclaration>(PredicateDeclaration());
+
+	predicate->m_name = context.parser.parseIdentifier();
+
+	// Flag predicate as correctly declared in the types section
+	predicate->setDeclared();
+
+	context.parser.skipWhiteSpace();
+
+	ExpressionContext expressionContext(domain, predicate->m_parameters);
+
+	// Parse arguments
+	expressions::Variable::parseTypedDeclarations(context, expressionContext);
+
+	context.parser.expect<std::string>(")");
+
+	domain.predicates().emplace_back(std::move(predicate));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void PredicateDeclaration::setDeclared()
+{
+	m_isDeclared = true;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool PredicateDeclaration::isDeclared() const
+{
+	return m_isDeclared;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &PredicateDeclaration::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Variables &PredicateDeclaration::arguments() const
+{
+	return m_parameters;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/PrimitiveType.cpp

@@ -0,0 +1,174 @@
+#include <plasp/pddl/expressions/PrimitiveType.h>
+
+#include <algorithm>
+
+#include <boost/assert.hpp>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PrimitiveType
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+PrimitiveType::PrimitiveType()
+:	m_isDirty{true}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+PrimitiveType::PrimitiveType(std::string name)
+:	m_isDirty{true},
+	m_name{name}
+{
+	BOOST_ASSERT(!m_name.empty());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void PrimitiveType::parseDeclaration(Context &context, Domain &domain)
+{
+	auto &types = domain.types();
+
+	context.parser.skipWhiteSpace();
+
+	const auto typeName = context.parser.parseIdentifier();
+
+	const auto match = std::find_if(types.cbegin(), types.cend(),
+		[&](const auto &primitiveType)
+		{
+			return primitiveType->name() == typeName;
+		});
+
+	// Return existing primitive type
+	if (match != types.cend())
+	{
+		auto *type = match->get();
+
+		type->setDirty();
+
+		return;
+	}
+
+	types.emplace_back(std::make_unique<PrimitiveType>(typeName));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void PrimitiveType::parseTypedDeclaration(Context &context, Domain &domain)
+{
+	auto &types = domain.types();
+
+	// Parse and store type
+	parseDeclaration(context, domain);
+
+	context.parser.skipWhiteSpace();
+
+	// Check for type inheritance
+	if (!context.parser.testAndSkip<char>('-'))
+		return;
+
+	domain.checkRequirement(Requirement::Type::Typing);
+
+	// If existing, parse and store parent type
+	auto *parentType = parseAndFind(context, domain);
+
+	parentType->setDirty(false);
+
+	// Assign parent type to all types that were previously flagged
+	std::for_each(types.begin(), types.end(),
+		[&](auto &childType)
+		{
+			if (!childType->isDirty())
+				return;
+
+			childType->m_parentTypes.push_back(parentType);
+			childType->setDirty(false);
+		});
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+PrimitiveType *PrimitiveType::parseAndFind(Context &context, Domain &domain)
+{
+	auto &parser = context.parser;
+
+	auto &types = domain.types();
+
+	parser.skipWhiteSpace();
+
+	const auto typeName = parser.parseIdentifier();
+
+	if (typeName.empty())
+		throw utils::ParserException(parser.coordinate(), "no type supplied");
+
+	const auto match = std::find_if(types.cbegin(), types.cend(),
+		[&](const auto &primitiveType)
+		{
+			return primitiveType->name() == typeName;
+		});
+
+	if (match == types.cend())
+	{
+		// Only "object" is allowed as an implicit type
+		if (typeName == "object" || typeName == "objects")
+		{
+			context.logger.logWarning(parser.coordinate(), "primitive type “" + typeName + "” should be declared");
+			types.emplace_back(std::make_unique<expressions::PrimitiveType>(typeName));
+		}
+		else
+			throw utils::ParserException(parser.coordinate(), "type “" + typeName + "” used but never declared");
+
+		return types.back().get();
+	}
+
+	auto *type = match->get();
+	type->setDirty();
+
+	return type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void PrimitiveType::setDirty(bool isDirty)
+{
+	m_isDirty = isDirty;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool PrimitiveType::isDirty() const
+{
+	return m_isDirty;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &PrimitiveType::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::vector<const PrimitiveType *> &PrimitiveType::parentTypes() const
+{
+	return m_parentTypes;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Type.cpp

@@ -0,0 +1,29 @@
+#include <plasp/pddl/expressions/Type.h>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/expressions/PrimitiveType.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Type
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression *parseExistingPrimitiveType(Context &context, ExpressionContext &expressionContext)
+{
+	return PrimitiveType::parseAndFind(context, expressionContext.domain);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Unsupported.cpp

@@ -0,0 +1,46 @@
+#include <plasp/pddl/expressions/Unsupported.h>
+
+#include <plasp/pddl/IO.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Unsupported
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+UnsupportedPointer Unsupported::parse(Context &context)
+{
+	auto &parser = context.parser;
+
+	auto expression = std::make_unique<Unsupported>(Unsupported());
+
+	parser.expect<std::string>("(");
+
+	expression->m_type = parser.parseIdentifier();
+
+	context.logger.logWarning(parser.coordinate(), "expression type “" + expression->m_type + "” currently unsupported in this context");
+
+	skipSection(parser);
+
+	return expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &Unsupported::type() const
+{
+	return m_type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/pddl/expressions/Variable.cpp

@@ -0,0 +1,204 @@
+#include <plasp/pddl/expressions/Variable.h>
+
+#include <algorithm>
+
+#include <boost/assert.hpp>
+
+#include <plasp/pddl/Context.h>
+#include <plasp/pddl/Domain.h>
+#include <plasp/pddl/ExpressionContext.h>
+#include <plasp/pddl/expressions/Either.h>
+#include <plasp/pddl/expressions/PrimitiveType.h>
+#include <plasp/pddl/expressions/Type.h>
+#include <plasp/utils/ParserException.h>
+
+namespace plasp
+{
+namespace pddl
+{
+namespace expressions
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Variable
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Variable::Variable()
+:	m_isDirty{false},
+	m_type{nullptr}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Variable::parseDeclaration(Context &context, Variables &parameters)
+{
+	auto &parser = context.parser;
+
+	parser.skipWhiteSpace();
+
+	parser.expect<std::string>("?");
+
+	auto variable = std::make_unique<Variable>(Variable());
+
+	variable->m_name = parser.parseIdentifier();
+
+	// Check if variable of that name already exists in the current scope
+	const auto match = std::find_if(parameters.cbegin(), parameters.cend(),
+		[&](const auto &parameter)
+		{
+			return parameter->name() == variable->m_name;
+		});
+
+	if (match != parameters.cend())
+		throw utils::ParserException(parser.coordinate(), "variable “" + variable->m_name + "” already declared in this scope");
+
+	// Flag variable for potentially upcoming type declaration
+	variable->setDirty();
+
+	parameters.emplace_back(std::move(variable));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Variable::parseTypedDeclaration(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+	auto &variables = expressionContext.parameters;
+
+	// Parse and store variable itself
+	parseDeclaration(context, variables);
+
+	auto &variable = variables.back();
+
+	parser.skipWhiteSpace();
+
+	// Check if the variable has a type declaration
+	if (!parser.testAndSkip<char>('-'))
+		return;
+
+	const auto setType =
+		[&](const auto *type)
+		{
+			// Set the argument type for all previously flagged arguments
+			std::for_each(variables.begin(), variables.end(),
+				[&](auto &variable)
+				{
+					if (!variable->isDirty())
+						return;
+
+					variable->setType(type);
+					variable->setDirty(false);
+				});
+		};
+
+	parser.skipWhiteSpace();
+
+	// Parse argument of "either" type (always begins with opening parenthesis)
+	if ((variable->m_eitherExpression = Either::parse(context, expressionContext, parseExistingPrimitiveType)))
+	{
+		setType(variable->m_eitherExpression.get());
+		return;
+	}
+
+	// Parse primitive type
+	const auto *type = PrimitiveType::parseAndFind(context, expressionContext.domain);
+
+	setType(type);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Variable::parseTypedDeclarations(Context &context, ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	while (parser.currentCharacter() != ')')
+	{
+		parseTypedDeclaration(context, expressionContext);
+
+		parser.skipWhiteSpace();
+	}
+
+	if (expressionContext.parameters.empty())
+		return;
+
+	// Check correct use of typing requirement
+	const auto typingUsed = (expressionContext.parameters.back()->type() != nullptr);
+
+	// If types are given, check that typing is a requirement
+	if (typingUsed)
+		expressionContext.checkRequirement(Requirement::Type::Typing);
+	// If no types are given, check that typing is not a requirement
+	else if (expressionContext.hasRequirement(Requirement::Type::Typing))
+		throw utils::ParserException(parser.coordinate(), "variable has undeclared type");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Variable *Variable::parseAndFind(Context &context, const ExpressionContext &expressionContext)
+{
+	auto &parser = context.parser;
+
+	parser.skipWhiteSpace();
+
+	parser.expect<std::string>("?");
+
+	const auto variableName = parser.parseIdentifier();
+
+	const auto &variables = expressionContext.parameters;
+
+	const auto match = std::find_if(variables.cbegin(), variables.cend(),
+		[&](const auto &variable)
+		{
+			return variable->name() == variableName;
+		});
+
+	if (match == variables.cend())
+		throw utils::ParserException(parser.coordinate(), "parameter “" + variableName + "” used but never declared");
+
+	return match->get();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const std::string &Variable::name() const
+{
+	return m_name;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const Expression *Variable::type() const
+{
+	return m_type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Variable::setDirty(bool isDirty)
+{
+	m_isDirty = isDirty;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool Variable::isDirty() const
+{
+	return m_isDirty;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Variable::setType(const Expression *type)
+{
+	m_type = type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+}

src/plasp/sas/AssignedVariable.cpp

@@ -4,8 +4,6 @@
 
 #include <boost/assert.hpp>
 
-#include <plasp/utils/Parsing.h>
-
 namespace plasp
 {
 namespace sas
@@ -33,24 +31,24 @@ AssignedVariable::AssignedVariable(const Variable &variable, const Value &value)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-AssignedVariable AssignedVariable::fromSAS(std::istream &istream, const Variables &variables)
+AssignedVariable AssignedVariable::fromSAS(utils::Parser<> &parser, const Variables &variables)
 {
 	AssignedVariable assignedVariable;
 
-	assignedVariable.m_variable = &Variable::referenceFromSAS(istream, variables);
-	assignedVariable.m_value = &Value::referenceFromSAS(istream, *assignedVariable.m_variable);
+	assignedVariable.m_variable = &Variable::referenceFromSAS(parser, variables);
+	assignedVariable.m_value = &Value::referenceFromSAS(parser, *assignedVariable.m_variable);
 
 	return assignedVariable;
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-AssignedVariable AssignedVariable::fromSAS(std::istream &istream, const Variable &variable)
+AssignedVariable AssignedVariable::fromSAS(utils::Parser<> &parser, const Variable &variable)
 {
 	AssignedVariable assignedVariable;
 
 	assignedVariable.m_variable = &variable;
-	assignedVariable.m_value = &Value::referenceFromSAS(istream, *assignedVariable.m_variable);
+	assignedVariable.m_value = &Value::referenceFromSAS(parser, *assignedVariable.m_variable);
 
 	return assignedVariable;
 }

src/plasp/sas/AxiomRule.cpp

@@ -3,7 +3,6 @@
 #include <iostream>
 
 #include <plasp/sas/VariableTransition.h>
-#include <plasp/utils/Parsing.h>
 
 namespace plasp
 {
@@ -24,24 +23,24 @@ AxiomRule::AxiomRule(AxiomRule::Conditions conditions, AxiomRule::Condition post
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-AxiomRule AxiomRule::fromSAS(std::istream &istream, const Variables &variables)
+AxiomRule AxiomRule::fromSAS(utils::Parser<> &parser, const Variables &variables)
 {
-	utils::parseExpected<std::string>(istream, "begin_rule");
+	parser.expect<std::string>("begin_rule");
 
-	const auto numberOfConditions = utils::parse<size_t>(istream);
+	const auto numberOfConditions = parser.parse<size_t>();
 
 	Conditions conditions;
 	conditions.reserve(numberOfConditions);
 
 	for (size_t j = 0; j < numberOfConditions; j++)
-		conditions.emplace_back(Condition::fromSAS(istream, variables));
+		conditions.emplace_back(Condition::fromSAS(parser, variables));
 
-	const auto variableTransition = VariableTransition::fromSAS(istream, variables);
+	const auto variableTransition = VariableTransition::fromSAS(parser, variables);
 
 	if (&variableTransition.valueBefore() != &Value::Any)
 		conditions.emplace_back(Condition(variableTransition.variable(), variableTransition.valueBefore()));
 
-	utils::parseExpected<std::string>(istream, "end_rule");
+	parser.expect<std::string>("end_rule");
 
 	const Condition postcondition(variableTransition.variable(), variableTransition.valueAfter());
 	const AxiomRule axiomRule(std::move(conditions), std::move(postcondition));

src/plasp/sas/Debugging.cpp

@@ -13,7 +13,7 @@ namespace sas
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-std::ostream &operator >>(std::ostream &ostream, const Description &description)
+utils::LogStream &operator<<(utils::LogStream &ostream, const Description &description)
 {
 	// Metric section
 	ostream << "uses action costs: " << (description.usesActionCosts() ? "yes" : "no") << std::endl;

src/plasp/sas/Description.cpp

@@ -8,7 +8,6 @@
 #include <boost/filesystem.hpp>
 
 #include <plasp/utils/ParserException.h>
-#include <plasp/utils/Parsing.h>
 #include <plasp/sas/VariableTransition.h>
 
 namespace plasp
@@ -29,22 +28,23 @@ Description::Description()
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Description Description::fromStream(std::istream &istream)
+Description Description::fromParser(utils::Parser<> &&parser)
 {
 	Description description;
+	description.parseContent(parser);
 
-	std::setlocale(LC_NUMERIC, "C");
+	return description;
+}
 
-	istream.exceptions(std::ifstream::failbit | std::ifstream::badbit);
+////////////////////////////////////////////////////////////////////////////////////////////////////
 
-	description.parseVersionSection(istream);
-	description.parseMetricSection(istream);
-	description.parseVariablesSection(istream);
-	description.parseMutexSection(istream);
-	description.parseInitialStateSection(istream);
-	description.parseGoalSection(istream);
-	description.parseOperatorSection(istream);
-	description.parseAxiomSection(istream);
+Description Description::fromStream(std::istream &istream)
+{
+	utils::Parser<> parser;
+	parser.read("std::cin", istream);
+
+	Description description;
+	description.parseContent(parser);
 
 	return description;
 }
@@ -54,11 +54,15 @@ Description Description::fromStream(std::istream &istream)
 Description Description::fromFile(const boost::filesystem::path &path)
 {
 	if (!boost::filesystem::is_regular_file(path))
-		throw std::runtime_error("File does not exist: \"" + path.string() + "\"");
+		throw std::runtime_error("File does not exist: “" + path.string() + "”");
 
-	std::ifstream fileStream(path.string(), std::ios::in);
+	utils::Parser<> parser;
+	parser.read(path);
 
-	return Description::fromStream(fileStream);
+	Description description;
+	description.parseContent(parser);
+
+	return description;
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -149,85 +153,111 @@ bool Description::usesConditionalEffects() const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseVersionSection(std::istream &istream) const
+bool Description::hasRequirements() const
 {
-	utils::parseExpected<std::string>(istream, "begin_version");
+	return usesActionCosts() || usesAxiomRules() || usesConditionalEffects();
+}
 
-	const auto formatVersion = utils::parse<size_t>(istream);
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Description::parseContent(utils::Parser<> &parser)
+{
+	parseVersionSection(parser);
+	parseMetricSection(parser);
+	parseVariablesSection(parser);
+	parseMutexSection(parser);
+	parseInitialStateSection(parser);
+	parseGoalSection(parser);
+	parseOperatorSection(parser);
+	parseAxiomSection(parser);
+
+	parser.skipWhiteSpace();
+
+	if (!parser.atEnd())
+		throw utils::ParserException(parser.coordinate(), "expected end of SAS description (perhaps, input contains two SAS descriptions?)");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void Description::parseVersionSection(utils::Parser<> &parser) const
+{
+	parser.expect<std::string>("begin_version");
+
+	const auto formatVersion = parser.parse<size_t>();
 
 	if (formatVersion != 3)
-		throw utils::ParserException("Unsupported SAS format version (" + std::to_string(formatVersion) + ")");
+		throw utils::ParserException(parser.coordinate(), "unsupported SAS format version (" + std::to_string(formatVersion) + ")");
 
-	utils::parseExpected<std::string>(istream, "end_version");
+	parser.expect<std::string>("end_version");
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseMetricSection(std::istream &istream)
+void Description::parseMetricSection(utils::Parser<> &parser)
 {
-	utils::parseExpected<std::string>(istream, "begin_metric");
+	parser.expect<std::string>("begin_metric");
 
-	m_usesActionCosts = utils::parse<bool>(istream);
+	m_usesActionCosts = parser.parse<bool>();
 
-	utils::parseExpected<std::string>(istream, "end_metric");
+	parser.expect<std::string>("end_metric");
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseVariablesSection(std::istream &istream)
+void Description::parseVariablesSection(utils::Parser<> &parser)
 {
-	const auto numberOfVariables = utils::parse<size_t>(istream);
+	const auto numberOfVariables = parser.parse<size_t>();
 	m_variables.reserve(numberOfVariables);
 
 	for (size_t i = 0; i < numberOfVariables; i++)
-		m_variables.emplace_back(Variable::fromSAS(istream));
+		m_variables.emplace_back(Variable::fromSAS(parser));
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseMutexSection(std::istream &istream)
+void Description::parseMutexSection(utils::Parser<> &parser)
 {
-	const auto numberOfMutexGroups = utils::parse<size_t>(istream);
+	const auto numberOfMutexGroups = parser.parse<size_t>();
 	m_mutexGroups.reserve(numberOfMutexGroups);
 
 	for (size_t i = 0; i < numberOfMutexGroups; i++)
-		m_mutexGroups.emplace_back(MutexGroup::fromSAS(istream, m_variables));
+		m_mutexGroups.emplace_back(MutexGroup::fromSAS(parser, m_variables));
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseInitialStateSection(std::istream &istream)
+void Description::parseInitialStateSection(utils::Parser<> &parser)
 {
-	m_initialState = std::make_unique<InitialState>(InitialState::fromSAS(istream, m_variables));
+	m_initialState = std::make_unique<InitialState>(InitialState::fromSAS(parser, m_variables));
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseGoalSection(std::istream &istream)
+void Description::parseGoalSection(utils::Parser<> &parser)
 {
-	m_goal = std::make_unique<Goal>(Goal::fromSAS(istream, m_variables));
+	m_goal = std::make_unique<Goal>(Goal::fromSAS(parser, m_variables));
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseOperatorSection(std::istream &istream)
+void Description::parseOperatorSection(utils::Parser<> &parser)
 {
-	const auto numberOfOperators = utils::parse<size_t>(istream);
+	const auto numberOfOperators = parser.parse<size_t>();
 	m_operators.reserve(numberOfOperators);
 
 	for (size_t i = 0; i < numberOfOperators; i++)
-		m_operators.emplace_back(Operator::fromSAS(istream, m_variables));
+		m_operators.emplace_back(Operator::fromSAS(parser, m_variables));
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Description::parseAxiomSection(std::istream &istream)
+void Description::parseAxiomSection(utils::Parser<> &parser)
 {
-	const auto numberOfAxiomRules = utils::parse<size_t>(istream);
+	const auto numberOfAxiomRules = parser.parse<size_t>();
 	m_axiomRules.reserve(numberOfAxiomRules);
 
 	for (size_t i = 0; i < numberOfAxiomRules; i++)
-		m_axiomRules.emplace_back(AxiomRule::fromSAS(istream, m_variables));
+		m_axiomRules.emplace_back(AxiomRule::fromSAS(parser, m_variables));
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////

src/plasp/sas/Effect.cpp

@@ -3,7 +3,6 @@
 #include <iostream>
 
 #include <plasp/sas/VariableTransition.h>
-#include <plasp/utils/Parsing.h>
 
 namespace plasp
 {
@@ -24,17 +23,17 @@ Effect::Effect(Conditions conditions, Condition postcondition)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Effect Effect::fromSAS(std::istream &istream, const Variables &variables, Conditions &preconditions)
+Effect Effect::fromSAS(utils::Parser<> &parser, const Variables &variables, Conditions &preconditions)
 {
 	Effect::Conditions conditions;
 
-	const auto numberOfEffectConditions = utils::parse<size_t>(istream);
+	const auto numberOfEffectConditions = parser.parse<size_t>();
 	conditions.reserve(numberOfEffectConditions);
 
 	for (size_t k = 0; k < numberOfEffectConditions; k++)
-		conditions.emplace_back(Condition::fromSAS(istream, variables));
+		conditions.emplace_back(Condition::fromSAS(parser, variables));
 
-	const auto variableTransition = VariableTransition::fromSAS(istream, variables);
+	const auto variableTransition = VariableTransition::fromSAS(parser, variables);
 
 	if (&variableTransition.valueBefore() != &Value::Any)
 		preconditions.emplace_back(Condition(variableTransition.variable(), variableTransition.valueBefore()));

src/plasp/sas/Goal.cpp

@@ -2,8 +2,6 @@
 
 #include <iostream>
 
-#include <plasp/utils/Parsing.h>
-
 namespace plasp
 {
 namespace sas
@@ -15,19 +13,19 @@ namespace sas
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Goal Goal::fromSAS(std::istream &istream, const Variables &variables)
+Goal Goal::fromSAS(utils::Parser<> &parser, const Variables &variables)
 {
 	Goal goal;
 
-	utils::parseExpected<std::string>(istream, "begin_goal");
+	parser.expect<std::string>("begin_goal");
 
-	const auto numberOfGoalFacts = utils::parse<size_t>(istream);
+	const auto numberOfGoalFacts = parser.parse<size_t>();
 	goal.m_facts.reserve(numberOfGoalFacts);
 
 	for (size_t i = 0; i < numberOfGoalFacts; i++)
-		goal.m_facts.emplace_back(Fact::fromSAS(istream, variables));
+		goal.m_facts.emplace_back(Fact::fromSAS(parser, variables));
 
-	utils::parseExpected<std::string>(istream, "end_goal");
+	parser.expect<std::string>("end_goal");
 
 	return goal;
 }

src/plasp/sas/InitialState.cpp

@@ -1,9 +1,5 @@
 #include <plasp/sas/InitialState.h>
 
-#include <iostream>
-
-#include <plasp/utils/Parsing.h>
-
 namespace plasp
 {
 namespace sas
@@ -15,18 +11,18 @@ namespace sas
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-InitialState InitialState::fromSAS(std::istream &istream, const Variables &variables)
+InitialState InitialState::fromSAS(utils::Parser<> &parser, const Variables &variables)
 {
 	InitialState initialState;
 
-	utils::parseExpected<std::string>(istream, "begin_state");
+	parser.expect<std::string>("begin_state");
 
 	initialState.m_facts.reserve(variables.size());
 
 	for (size_t i = 0; i < variables.size(); i++)
-		initialState.m_facts.emplace_back(Fact::fromSAS(istream, variables[i]));
+		initialState.m_facts.emplace_back(Fact::fromSAS(parser, variables[i]));
 
-	utils::parseExpected<std::string>(istream, "end_state");
+	parser.expect<std::string>("end_state");
 
 	return initialState;
 }

src/plasp/sas/MutexGroup.cpp

@@ -2,7 +2,7 @@
 
 #include <iostream>
 
-#include <plasp/utils/Parsing.h>
+#include <plasp/utils/ParserException.h>
 
 namespace plasp
 {
@@ -15,24 +15,24 @@ namespace sas
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-MutexGroup MutexGroup::fromSAS(std::istream &istream, const Variables &variables)
+MutexGroup MutexGroup::fromSAS(utils::Parser<> &parser, const Variables &variables)
 {
 	MutexGroup mutexGroup;
 
-	utils::parseExpected<std::string>(istream, "begin_mutex_group");
+	parser.expect<std::string>("begin_mutex_group");
 
-	const auto numberOfFacts = utils::parse<size_t>(istream);
+	const auto numberOfFacts = parser.parse<size_t>();
 	mutexGroup.m_facts.reserve(numberOfFacts);
 
 	for (size_t j = 0; j < numberOfFacts; j++)
 	{
-		mutexGroup.m_facts.emplace_back(Fact::fromSAS(istream, variables));
+		mutexGroup.m_facts.emplace_back(Fact::fromSAS(parser, variables));
 
 		if (mutexGroup.m_facts[j].value() == Value::None)
-			throw utils::ParserException("Mutex groups must not contain <none of those> values");
+			throw utils::ParserException(parser.coordinate(), "mutex groups must not contain <none of those> values");
 	}
 
-	utils::parseExpected<std::string>(istream, "end_mutex_group");
+	parser.expect<std::string>("end_mutex_group");
 
 	return mutexGroup;
 }

src/plasp/sas/Operator.cpp

@@ -4,7 +4,7 @@
 #include <limits>
 
 #include <plasp/sas/VariableTransition.h>
-#include <plasp/utils/Parsing.h>
+#include <plasp/utils/Formatting.h>
 
 namespace plasp
 {
@@ -17,40 +17,40 @@ namespace sas
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Operator Operator::fromSAS(std::istream &istream, const Variables &variables)
+Operator Operator::fromSAS(utils::Parser<> &parser, const Variables &variables)
 {
 	Operator operator_;
 
-	utils::parseExpected<std::string>(istream, "begin_operator");
+	parser.expect<std::string>("begin_operator");
 
-	operator_.m_predicate = Predicate::fromSAS(istream);
+	operator_.m_predicate = Predicate::fromSAS(parser);
 
-	const auto numberOfPrevailConditions = utils::parse<size_t>(istream);
+	const auto numberOfPrevailConditions = parser.parse<size_t>();
 	operator_.m_preconditions.reserve(numberOfPrevailConditions);
 
 	for (size_t j = 0; j < numberOfPrevailConditions; j++)
-		operator_.m_preconditions.emplace_back(Condition::fromSAS(istream, variables));
+		operator_.m_preconditions.emplace_back(Condition::fromSAS(parser, variables));
 
-	const auto numberOfEffects = utils::parse<size_t>(istream);
+	const auto numberOfEffects = parser.parse<size_t>();
 	operator_.m_effects.reserve(numberOfEffects);
 
 	for (size_t j = 0; j < numberOfEffects; j++)
-		operator_.m_effects.emplace_back(Effect::fromSAS(istream, variables, operator_.m_preconditions));
+		operator_.m_effects.emplace_back(Effect::fromSAS(parser, variables, operator_.m_preconditions));
 
-	operator_.m_costs = utils::parse<size_t>(istream);
+	operator_.m_costs = parser.parse<size_t>();
 
-	utils::parseExpected<std::string>(istream, "end_operator");
+	parser.expect<std::string>("end_operator");
 
 	return operator_;
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Operator::printPredicateAsASP(std::ostream &ostream) const
+void Operator::printPredicateAsASP(utils::LogStream &outputStream) const
 {
-	ostream << "action(";
-	m_predicate.printAsASP(ostream);
-	ostream << ")";
+	outputStream << utils::Keyword("action") << "(";
+	m_predicate.printAsASP(outputStream);
+	outputStream << ")";
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////