diff --git a/.gitmodules b/.gitmodules
index b4b58b4..995e15b 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "lib/catch"]
 	path = lib/catch
 	url = https://github.com/philsquared/Catch
+[submodule "lib/variant"]
+	path = lib/variant
+	url = https://github.com/mapbox/variant
diff --git a/lib/pddlparse/include/pddlparse/AST.h b/lib/pddlparse/include/pddlparse/AST.h
index 882d8ca..7c5d388 100644
--- a/lib/pddlparse/include/pddlparse/AST.h
+++ b/lib/pddlparse/include/pddlparse/AST.h
@@ -26,7 +26,7 @@ namespace ast
 
 struct Constant
 {
-	explicit Constant(ConstantDeclaration &declaration)
+	explicit Constant(ConstantDeclaration *declaration)
 	:	declaration{declaration}
 	{
 	}
@@ -36,7 +36,7 @@ struct Constant
 	Constant(Constant &&other) = default;
 	Constant &operator=(Constant &&other) = default;
 
-	ConstantDeclaration &declaration;
+	ConstantDeclaration *declaration;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -51,8 +51,8 @@ struct ConstantDeclaration
 
 	ConstantDeclaration(const ConstantDeclaration &other) = delete;
 	ConstantDeclaration &operator=(const ConstantDeclaration &&other) = delete;
-	ConstantDeclaration(ConstantDeclaration &&other) = default;
-	ConstantDeclaration &operator=(ConstantDeclaration &&other) = default;
+	ConstantDeclaration(ConstantDeclaration &&other) = delete;
+	ConstantDeclaration &operator=(ConstantDeclaration &&other) = delete;
 
 	std::string name;
 	std::experimental::optional<Type> type;
@@ -79,7 +79,7 @@ struct Dummy
 
 struct PrimitiveType
 {
-	explicit PrimitiveType(PrimitiveTypeDeclaration &declaration)
+	explicit PrimitiveType(PrimitiveTypeDeclaration *declaration)
 	:	declaration{declaration}
 	{
 	}
@@ -89,7 +89,7 @@ struct PrimitiveType
 	PrimitiveType(PrimitiveType &&other) = default;
 	PrimitiveType &operator=(PrimitiveType &&other) = default;
 
-	PrimitiveTypeDeclaration &declaration;
+	PrimitiveTypeDeclaration *declaration;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -103,11 +103,11 @@ struct PrimitiveTypeDeclaration
 
 	PrimitiveTypeDeclaration(const PrimitiveTypeDeclaration &other) = delete;
 	PrimitiveTypeDeclaration &operator=(const PrimitiveTypeDeclaration &&other) = delete;
-	PrimitiveTypeDeclaration(PrimitiveTypeDeclaration &&other) = default;
-	PrimitiveTypeDeclaration &operator=(PrimitiveTypeDeclaration &&other) = default;
+	PrimitiveTypeDeclaration(PrimitiveTypeDeclaration &&other) = delete;
+	PrimitiveTypeDeclaration &operator=(PrimitiveTypeDeclaration &&other) = delete;
 
 	std::string name;
-	std::vector<PrimitiveType> parentTypes;
+	std::vector<PrimitiveTypePointer> parentTypes;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -127,7 +127,7 @@ struct Unsupported
 
 struct Variable
 {
-	explicit Variable(VariableDeclaration &declaration)
+	explicit Variable(VariableDeclaration *declaration)
 	:	declaration{declaration}
 	{
 	}
@@ -137,7 +137,7 @@ struct Variable
 	Variable(Variable &&other) = default;
 	Variable &operator=(Variable &&other) = default;
 
-	VariableDeclaration &declaration;
+	VariableDeclaration *declaration;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -152,8 +152,8 @@ struct VariableDeclaration
 
 	VariableDeclaration(const VariableDeclaration &other) = delete;
 	VariableDeclaration &operator=(const VariableDeclaration &&other) = delete;
-	VariableDeclaration(VariableDeclaration &&other) = default;
-	VariableDeclaration &operator=(VariableDeclaration &&other) = default;
+	VariableDeclaration(VariableDeclaration &&other) = delete;
+	VariableDeclaration &operator=(VariableDeclaration &&other) = delete;
 
 	std::string name;
 	std::experimental::optional<Type> type;
@@ -165,7 +165,7 @@ struct VariableDeclaration
 
 struct Predicate
 {
-	explicit Predicate(PredicateDeclaration &declaration)
+	explicit Predicate(PredicateDeclaration *declaration)
 	:	declaration{declaration}
 	{
 	}
@@ -176,8 +176,7 @@ struct Predicate
 	Predicate &operator=(Predicate &&other) = default;
 
 	Terms arguments;
-
-	PredicateDeclaration &declaration;
+	PredicateDeclaration *declaration;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -416,9 +415,9 @@ struct Action
 
 	std::string name;
 
-	ast::VariableDeclarations parameters;
-	std::experimental::optional<ast::Precondition> precondition;
-	std::experimental::optional<ast::Effect> effect;
+	VariableDeclarations parameters;
+	std::experimental::optional<Precondition> precondition;
+	std::experimental::optional<Effect> effect;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -429,15 +428,15 @@ struct Domain
 
 	Domain(const Domain &other) = delete;
 	Domain &operator=(const Domain &&other) = delete;
-	Domain(Domain &&other) = default;
-	Domain &operator=(Domain &&other) = default;
+	Domain(Domain &&other) = delete;
+	Domain &operator=(Domain &&other) = delete;
 
 	std::string name;
 	Requirements requirements;
-	ast::PrimitiveTypeDeclarations types;
-	ast::ConstantDeclarations constants;
-	ast::PredicateDeclarations predicates;
-	std::vector<Action> actions;
+	PrimitiveTypeDeclarations types;
+	ConstantDeclarations constants;
+	PredicateDeclarations predicates;
+	Actions actions;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -451,7 +450,7 @@ struct InitialState
 	InitialState(InitialState &&other) = default;
 	InitialState &operator=(InitialState &&other) = default;
 
-	ast::Facts facts;
+	Facts facts;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -460,17 +459,22 @@ struct Problem
 {
 	Problem() = default;
 
+	Problem(Domain *domain)
+	:	domain{domain}
+	{
+	}
+
 	Problem(const Problem &other) = delete;
 	Problem &operator=(const Problem &&other) = delete;
 	Problem(Problem &&other) = default;
 	Problem &operator=(Problem &&other) = default;
 
-	Domain &domain;
+	Domain *domain;
 	std::string name;
 	Requirements requirements;
-	ast::ConstantDeclarations objects;
+	ConstantDeclarations objects;
 	InitialState initialState;
-	std::experimental::optional<ast::Goal> goal;
+	std::experimental::optional<Goal> goal;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -512,8 +516,8 @@ struct Description
 	Description(Description &&other) = default;
 	Description &operator=(Description &&other) = default;
 
-	Domain domain;
-	std::experimental::optional<Problem> problem;
+	DomainPointer domain;
+	std::experimental::optional<ProblemPointer> problem;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/lib/pddlparse/include/pddlparse/ASTForward.h b/lib/pddlparse/include/pddlparse/ASTForward.h
index 206f4e3..c14d06e 100644
--- a/lib/pddlparse/include/pddlparse/ASTForward.h
+++ b/lib/pddlparse/include/pddlparse/ASTForward.h
@@ -26,27 +26,37 @@ namespace ast
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 struct Constant;
+using ConstantPointer = std::unique_ptr<Constant>;
 struct ConstantDeclaration;
-using ConstantDeclarations = std::vector<ConstantDeclaration>;
+using ConstantDeclarationPointer = std::unique_ptr<ConstantDeclaration>;
+using ConstantDeclarations = std::vector<ConstantDeclarationPointer>;
 struct Dummy;
+using DummyPointer = std::unique_ptr<Dummy>;
 struct PrimitiveType;
-using PrimitiveTypes = std::vector<PrimitiveType>;
+using PrimitiveTypePointer = std::unique_ptr<PrimitiveType>;
+using PrimitiveTypes = std::vector<PrimitiveTypePointer>;
 struct PrimitiveTypeDeclaration;
-using PrimitiveTypeDeclarations = std::vector<PrimitiveTypeDeclaration>;
+using PrimitiveTypeDeclarationPointer = std::unique_ptr<PrimitiveTypeDeclaration>;
+using PrimitiveTypeDeclarations = std::vector<PrimitiveTypeDeclarationPointer>;
 struct Unsupported;
+using UnsupportedPointer = std::unique_ptr<Unsupported>;
 struct Variable;
-using Variables = std::vector<Variable>;
+using VariablePointer = std::unique_ptr<Variable>;
+using Variables = std::vector<VariablePointer>;
 struct VariableDeclaration;
-using VariableDeclarations = std::vector<VariableDeclaration>;
+using VariableDeclarationPointer = std::unique_ptr<VariableDeclaration>;
+using VariableDeclarations = std::vector<VariableDeclarationPointer>;
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // Compounds
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 struct Predicate;
-using Predicates = std::vector<Predicate>;
+using PredicatePointer = std::unique_ptr<Predicate>;
+using Predicates = std::vector<PredicatePointer>;
 struct PredicateDeclaration;
-using PredicateDeclarations = std::vector<PredicateDeclaration>;
+using PredicateDeclarationPointer = std::unique_ptr<PredicateDeclaration>;
+using PredicateDeclarations = std::vector<PredicateDeclarationPointer>;
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // Expressions
@@ -55,29 +65,53 @@ using PredicateDeclarations = std::vector<PredicateDeclaration>;
 template<class Argument>
 struct And;
 template<class Argument>
+using AndPointer = std::unique_ptr<And<Argument>>;
+template<class Argument>
 struct At;
 template<class Argument>
+using AtPointer = std::unique_ptr<At<Argument>>;
+template<class Argument>
 struct Either;
 template<class Argument>
+using EitherPointer = std::unique_ptr<Either<Argument>>;
+template<class Argument>
 struct Exists;
 template<class Argument>
+using ExistsPointer = std::unique_ptr<Exists<Argument>>;
+template<class Argument>
 struct ForAll;
 template<class Argument>
+using ForAllPointer = std::unique_ptr<ForAll<Argument>>;
+template<class Argument>
 struct Imply;
 template<class Argument>
+using ImplyPointer = std::unique_ptr<Imply<Argument>>;
+template<class Argument>
 struct Not;
 template<class Argument>
+using NotPointer = std::unique_ptr<Not<Argument>>;
+template<class Argument>
 struct Or;
+template<class Argument>
+using OrPointer = std::unique_ptr<Or<Argument>>;
 template<class ArgumentLeft, class ArgumentRight>
 struct When;
+template<class ArgumentLeft, class ArgumentRight>
+using WhenPointer = std::unique_ptr<When<ArgumentLeft, ArgumentRight>>;
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // PDDL Structure
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+struct Action;
+using ActionPointer = std::unique_ptr<Action>;
+using Actions = std::vector<ActionPointer>;
 struct Description;
+using DescriptionPointer = std::unique_ptr<Description>;
 struct Domain;
+using DomainPointer = std::unique_ptr<Domain>;
 struct Problem;
+using ProblemPointer = std::unique_ptr<Problem>;
 enum class Requirement;
 using Requirements = std::vector<Requirement>;
 
@@ -88,8 +122,8 @@ using Requirements = std::vector<Requirement>;
 namespace detail
 {
 using TermT = Variant<
-	Constant,
-	Variable>;
+	ConstantPointer,
+	VariablePointer>;
 }
 
 class Term : public detail::TermT
@@ -104,8 +138,8 @@ using Terms = std::vector<Term>;
 namespace detail
 {
 using AtomicFormulaT = Variant<
-	Predicate,
-	Unsupported>;
+	PredicatePointer,
+	UnsupportedPointer>;
 }
 
 class AtomicFormula : public detail::AtomicFormulaT
@@ -121,13 +155,13 @@ namespace detail
 {
 using PreconditionT = Variant<
 	AtomicFormula,
-	And<Precondition>,
-	Exists<Precondition>,
-	ForAll<Precondition>,
-	Imply<Precondition>,
-	Not<Precondition>,
-	Or<Precondition>,
-	Unsupported>;
+	AndPointer<Precondition>,
+	ExistsPointer<Precondition>,
+	ForAllPointer<Precondition>,
+	ImplyPointer<Precondition>,
+	NotPointer<Precondition>,
+	OrPointer<Precondition>,
+	UnsupportedPointer>;
 }
 
 class Precondition : public detail::PreconditionT
@@ -145,11 +179,11 @@ namespace detail
 {
 using EffectT = Variant<
 	AtomicFormula,
-	And<Effect>,
-	ForAll<Effect>,
-	Not<Effect>,
-	When<Precondition, Effect>,
-	Unsupported>;
+	AndPointer<Effect>,
+	ForAllPointer<Effect>,
+	NotPointer<Effect>,
+	WhenPointer<Precondition, Effect>,
+	UnsupportedPointer>;
 }
 
 class Effect : public detail::EffectT
@@ -162,8 +196,8 @@ class Effect : public detail::EffectT
 namespace detail
 {
 using TypeT = Variant<
-	Either<PrimitiveType>,
-	PrimitiveType>;
+	EitherPointer<PrimitiveTypePointer>,
+	PrimitiveTypePointer>;
 }
 
 class Type : public detail::TypeT
@@ -177,7 +211,7 @@ namespace detail
 {
 using LiteralT = Variant<
 	AtomicFormula,
-	Not<AtomicFormula>>;
+	NotPointer<AtomicFormula>>;
 }
 
 class Literal : public detail::LiteralT
@@ -193,7 +227,7 @@ namespace detail
 {
 using FactT = Variant<
 	AtomicFormula,
-	At<Literal>>;
+	AtPointer<Literal>>;
 }
 
 class Fact : public detail::FactT
diff --git a/lib/pddlparse/include/pddlparse/Context.h b/lib/pddlparse/include/pddlparse/Context.h
new file mode 100644
index 0000000..6859944
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/Context.h
@@ -0,0 +1,49 @@
+#ifndef __PDDL_PARSE__CONTEXT_H
+#define __PDDL_PARSE__CONTEXT_H
+
+#include <functional>
+
+#include <pddlparse/Tokenizer.h>
+
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Context
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct Context
+{
+	constexpr static const char *auxiliaryPrefix()
+	{
+		return "__plasp_";
+	}
+
+	// TODO: replace std::string with char *
+	using WarningCallback = std::function<void (tokenize::Location, const std::string &)>;
+
+	Context() = default;
+	~Context() = default;
+
+	explicit Context(Tokenizer &&tokenizer, WarningCallback warningCallback)
+	:	tokenizer{std::move(tokenizer)},
+		warningCallback{warningCallback}
+	{
+	}
+
+	Context(const Context &other) = delete;
+	Context &operator=(const Context &other) = delete;
+	Context(Context &&other) = default;
+	Context &operator=(Context &&other) = default;
+
+	Tokenizer tokenizer;
+	WarningCallback warningCallback;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/Parse.h b/lib/pddlparse/include/pddlparse/Parse.h
new file mode 100644
index 0000000..053b332
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/Parse.h
@@ -0,0 +1,24 @@
+#ifndef __PDDL_PARSE__PARSE_H
+#define __PDDL_PARSE__PARSE_H
+
+#include <experimental/optional>
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Parse
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::Description parseDescription(Context &context);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/Variant.h b/lib/pddlparse/include/pddlparse/Variant.h
index 879e9c3..f790d34 100644
--- a/lib/pddlparse/include/pddlparse/Variant.h
+++ b/lib/pddlparse/include/pddlparse/Variant.h
@@ -1,233 +1,20 @@
 #ifndef __PDDL_PARSE__VARIANT_H
 #define __PDDL_PARSE__VARIANT_H
 
-#include <cassert>
-#include <memory>
-#include <ostream>
-#include <type_traits>
+#include <mapbox/variant.hpp>
 
 namespace pddl
 {
 
-////////////////////////////////////////////////////////////////////////////////////////////////////
-//
-// Variant (from clingo, written by Roland Kaminski)
-//
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-namespace detail {
-
-template <class T, class... U>
-struct TypeInList : std::false_type { };
-
-template <class T, class... U>
-struct TypeInList<T, T, U...> : std::true_type { };
-
-template <class T, class V, class... U>
-struct TypeInList<T, V, U...> : TypeInList<T, U...> { };
-
-template <unsigned, class... U>
-struct VariantHolder;
-
-template <unsigned n>
-struct VariantHolder<n> {
-	bool check_type() const { return type_ == 0; }
-	void emplace() { }
-	void emplace2() { }
-	void copy(VariantHolder const &) { }
-	void destroy() {
-		type_ = 0;
-		data_ = nullptr;
-	}
-	void print(std::ostream &) const { }
-	void swap(VariantHolder &other) {
-		std::swap(type_, other.type_);
-		std::swap(data_, other.data_);
-	}
-	unsigned type_ = 0;
-	void *data_ = nullptr;
-};
-
-template <unsigned n, class T, class... U>
-struct VariantHolder<n, T, U...> : VariantHolder<n+1, U...>{
-	using Helper = VariantHolder<n+1, U...>;
-	using Helper::check_type;
-	using Helper::emplace;
-	using Helper::emplace2;
-	using Helper::data_;
-	using Helper::type_;
-	bool check_type(T *) const { return type_ == n; }
-	template <class... Args>
-	void emplace(T *, Args&& ...x) {
-		data_ = new T{std::forward<Args>(x)...};
-		type_ = n;
-	}
-	// NOTE: http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1467
-	template <class... Args>
-	void emplace2(T *, Args&& ...x) {
-		data_ = new T(std::forward<Args>(x)...);
-		type_ = n;
-	}
-	void copy(VariantHolder const &src) {
-		if (src.type_ == n) {
-			data_ = new T(*static_cast<T const*>(src.data_));
-			type_ = src.type_;
-		}
-		Helper::copy(src);
-	}
-	// NOTE: workaround for visual studio (C++14 can also simply use auto)
-#   define CLINGO_VARIANT_RETURN(Type) decltype(std::declval<V>().visit(std::declval<Type&>(), std::declval<Args>()...))
-	template <class V, class... Args>
-	using Ret_ = CLINGO_VARIANT_RETURN(T);
-	template <class V, class... Args>
-	using ConstRet_ = CLINGO_VARIANT_RETURN(T const);
-	// non-const
-	template <class V, class U1, class... U2, class... Args>
-	auto accept_(V &&visitor, Args &&... args) -> CLINGO_VARIANT_RETURN(T) {
-		static_assert(std::is_same<Ret_<V, Args...>, typename Helper::template Ret_<V, Args...>>::value, "");
-		return n == type_
-			? visitor.visit(*static_cast<T*>(data_), std::forward<Args>(args)...)
-			: Helper::template accept<V>(std::forward<V>(visitor), std::forward<Args>(args)...);
-	}
-	template <class V, class... Args>
-	auto accept_(V &&visitor, Args &&... args) -> CLINGO_VARIANT_RETURN(T) {
-		assert(n == type_);
-		return visitor.visit(*static_cast<T*>(data_), std::forward<Args>(args)...);
-	}
-	template <class V, class... Args>
-	auto accept(V &&visitor, Args &&... args) -> CLINGO_VARIANT_RETURN(T) {
-		return accept_<V, U...>(std::forward<V>(visitor), std::forward<Args>(args)...);
-	}
-	// const
-	template <class V, class U1, class... U2, class... Args>
-	auto accept_(V &&visitor, Args &&... args) const -> CLINGO_VARIANT_RETURN(T const) {
-		static_assert(std::is_same<ConstRet_<V, Args...>, typename Helper::template ConstRet_<V, Args...>>::value, "");
-		return n == type_
-			? visitor.visit(*static_cast<T const *>(data_), std::forward<Args>(args)...)
-			: Helper::template accept<V>(std::forward<V>(visitor), std::forward<Args>(args)...);
-	}
-	template <class V, class... Args>
-	auto accept_(V &&visitor, Args &&... args) const -> CLINGO_VARIANT_RETURN(T const) {
-		assert(n == type_);
-		return visitor.visit(*static_cast<T const *>(data_), std::forward<Args>(args)...);
-	}
-	template <class V, class... Args>
-	auto accept(V &&visitor, Args &&... args) const -> CLINGO_VARIANT_RETURN(T const) {
-		return accept_<V, U...>(std::forward<V>(visitor), std::forward<Args>(args)...);
-	}
-#   undef CLINGO_VARIANT_RETURN
-	void destroy() {
-		if (n == type_) { delete static_cast<T*>(data_); }
-		Helper::destroy();
-	}
-	void print(std::ostream &out) const {
-		if (n == type_) { out << *static_cast<T const*>(data_); }
-		Helper::print(out);
-	}
-};
-
-}
-
-template <class... T>
-class Variant {
-	using Holder = detail::VariantHolder<1, T...>;
-public:
-	Variant(Variant const &other) : Variant(other.data_) { }
-	Variant(Variant &&other) noexcept { data_.swap(other.data_); }
-	template <class U>
-	Variant(U &&u, typename std::enable_if<detail::TypeInList<U, T...>::value>::type * = nullptr) { emplace2<U>(std::forward<U>(u)); }
-	template <class U>
-	Variant(U &u, typename std::enable_if<detail::TypeInList<U, T...>::value>::type * = nullptr) { emplace2<U>(u); }
-	template <class U>
-	Variant(U const &u, typename std::enable_if<detail::TypeInList<U, T...>::value>::type * = nullptr) { emplace2<U>(u); }
-	template <class U, class... Args>
-	static Variant make(Args&& ...args) {
-		Variant<T...> x;
-		x.data_.emplace(static_cast<U*>(nullptr), std::forward<Args>(args)...);
-		return std::move(x);
-	}
-	~Variant() { data_.destroy(); }
-	Variant &operator=(Variant const &other) { return *this = other.data_; }
-	Variant &operator=(Variant &&other) noexcept { return *this = std::move(other.data_); }
-	template <class U>
-	typename std::enable_if<detail::TypeInList<U, T...>::value, Variant>::type &operator=(U &&u) {
-		emplace2<U>(std::forward<U>(u));
-		return *this;
-	}
-	template <class U>
-	typename std::enable_if<detail::TypeInList<U, T...>::value, Variant>::type &operator=(U &u) {
-		emplace2<U>(u);
-		return *this;
-	}
-	template <class U>
-	typename std::enable_if<detail::TypeInList<U, T...>::value, Variant>::type &operator=(U const &u) {
-		emplace2<U>(u);
-		return *this;
-	}
-	template <class U>
-	U &get() {
-		if (!data_.check_type(static_cast<U*>(nullptr))) { throw std::bad_cast(); }
-		return *static_cast<U*>(data_.data_);
-	}
-	template <class U>
-	U const &get() const {
-		if (!data_.check_type(static_cast<U*>(nullptr))) { throw std::bad_cast(); }
-		return *static_cast<U*>(data_.data_);
-	}
-	template <class U, class... Args>
-	void emplace(Args&& ...args) {
-		Variant<T...> x;
-		x.data_.emplace(static_cast<U*>(nullptr), std::forward<Args>(args)...);
-		data_.swap(x.data_);
-	}
-	template <class U>
-	bool is() const { return data_.check_type(static_cast<U*>(nullptr)); }
-	void swap(Variant &other) { data_.swap(other.data_); }
-	template <class V, class... Args>
-	typename Holder::template Ret_<V, Args...> accept(V &&visitor, Args &&... args) {
-		return data_.accept(std::forward<V>(visitor), std::forward<Args>(args)...);
-	}
-	template <class V, class... Args>
-	typename Holder::template ConstRet_<V, Args...> accept(V &&visitor, Args &&... args) const {
-		return data_.accept(std::forward<V>(visitor), std::forward<Args>(args)...);
-	}
-	friend std::ostream &operator<<(std::ostream &out, Variant const &x) {
-		x.data_.print(out);
-		return out;
-	}
-
-private:
-	Variant() { }
-	Variant(Holder const &data) {
-		data_.copy(data);
-	}
-	Variant &operator=(Holder const &data) {
-		Variant x(data);
-		data_.swap(x.data_);
-		return *this;
-	}
-	Variant &operator=(Holder &&data) noexcept {
-		Holder x;
-		x.swap(data);
-		// Destroy the old data_ only after securing the new data
-		// Otherwise, data would be destroyed together with data_ if it was a descendant of data_
-		data_.destroy();
-		x.swap(data_);
-		return *this;
-	}
-	template <class U, class... Args>
-	void emplace2(Args&& ...args) {
-		Variant<T...> x;
-		x.data_.emplace2(static_cast<U*>(nullptr), std::forward<Args>(args)...);
-		data_.swap(x.data_);
-	}
-
-private:
-	Holder data_;
-};
+template<class... Types>
+using Variant = mapbox::util::variant<Types...>;
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 }
 
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 #endif
diff --git a/lib/pddlparse/include/pddlparse/detail/ASTContext.h b/lib/pddlparse/include/pddlparse/detail/ASTContext.h
new file mode 100644
index 0000000..7e12161
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/ASTContext.h
@@ -0,0 +1,48 @@
+#ifndef __PDDL_PARSE__DETAIL__AST_CONTEXT_H
+#define __PDDL_PARSE__DETAIL__AST_CONTEXT_H
+
+#include <pddlparse/AST.h>
+#include <pddlparse/detail/VariableStack.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ASTContext
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct ASTContext
+{
+	ASTContext(ast::Description &description)
+	:	domain{description.domain.get()},
+		problem{description.problem.value() ? std::experimental::optional<ast::Problem *>(description.problem.value().get()) : std::experimental::nullopt}
+	{
+	}
+
+	ASTContext(ast::Domain &domain)
+	:	domain{&domain}
+	{
+	}
+
+	ASTContext(ast::Problem &problem)
+	:	domain{problem.domain},
+		problem{&problem}
+	{
+	}
+
+	ast::Domain *domain;
+	std::experimental::optional<ast::Problem *> problem;
+
+	VariableStack variables;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/ASTCopy.h b/lib/pddlparse/include/pddlparse/detail/ASTCopy.h
new file mode 100644
index 0000000..ced121d
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/ASTCopy.h
@@ -0,0 +1,161 @@
+#ifndef __PDDL_PARSE__DETAIL__AST_COPY_H
+#define __PDDL_PARSE__DETAIL__AST_COPY_H
+
+#include <pddlparse/AST.h>
+
+namespace pddl
+{
+namespace ast
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ASTCopy
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Primitives
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline Constant deepCopy(Constant &other);
+inline PrimitiveType deepCopy(PrimitiveType &other);
+inline Variable deepCopy(Variable &other);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Expressions: Base Classes
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived, class ArgumentLeft, class ArgumentRight = ArgumentLeft>
+inline Binary<Derived, ArgumentLeft, ArgumentRight> deepCopy(Binary<Derived, ArgumentLeft, ArgumentRight> &other);
+template<class Derived, class Argument>
+inline NAry<Derived, Argument> deepCopy(NAry<Derived, Argument> &other);
+template<class Derived, class Argument>
+inline Quantified<Derived, Argument> deepCopy(Quantified<Derived, Argument> &other);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Expressions
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Argument>
+inline At<Argument> deepCopy(At<Argument> &other);
+template<class Argument>
+inline Not<Argument> deepCopy(Not<Argument> &other);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Variants
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline ast::Term deepCopy(ast::Term &other);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Primitives
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Constant deepCopy(Constant &other)
+{
+	return Constant(other.declaration);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+PrimitiveType deepCopy(PrimitiveType &other)
+{
+	return PrimitiveType(other.declaration);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+Variable deepCopy(Variable &other)
+{
+	return Variable(other.declaration);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Expressions: Base Classes
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived, class ArgumentLeft, class ArgumentRight>
+Binary<Derived, ArgumentLeft, ArgumentRight> deepCopy(Binary<Derived, ArgumentLeft, ArgumentRight> &other)
+{
+	auto argumentLeft = deepCopy(other.argumentLeft);
+	auto argumentRight = deepCopy(other.argumentRight);
+
+	return Binary<Derived, ArgumentLeft, ArgumentRight>(std::move(argumentLeft), std::move(argumentRight));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived, class Argument>
+NAry<Derived, Argument> deepCopy(NAry<Derived, Argument> &other)
+{
+	typename NAry<Derived, Argument>::Arguments arguments;
+	arguments.reserve(other.arguments.size());
+
+	for (auto &argument : other.arguments)
+		arguments.emplace_back(deepCopy(argument));
+
+	return NAry<Derived, Argument>(std::move(arguments));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived, class Argument>
+Quantified<Derived, Argument> deepCopy(Quantified<Derived, Argument> &other)
+{
+	auto argument = deepCopy(other.argument);
+
+	return Quantified<Derived, Argument>(std::move(argument));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Expressions
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Argument>
+At<Argument> deepCopy(At<Argument> &other)
+{
+	auto argument = deepCopy(other.argument);
+
+	return At<Argument>(other.timePoint, std::move(argument));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Argument>
+Not<Argument> deepCopy(Not<Argument> &other)
+{
+	auto argument = deepCopy(other.argument);
+
+	return Not<Argument>(std::move(argument));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Variants
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct DeepCopyVisitor
+{
+	template<class Argument>
+	Argument visit(Argument &other)
+	{
+		return deepCopy(other);
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Unique Pointers
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class T>
+std::unique_ptr<T> deepCopy(std::unique_ptr<T> &other)
+{
+	return std::make_unique<T>(deepCopy(*other));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/Requirements.h b/lib/pddlparse/include/pddlparse/detail/Requirements.h
new file mode 100644
index 0000000..e9e7dc9
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/Requirements.h
@@ -0,0 +1,33 @@
+#ifndef __PDDL_PARSE__DETAIL__REQUIREMENTS_H
+#define __PDDL_PARSE__DETAIL__REQUIREMENTS_H
+
+#include <iostream>
+
+#include <pddlparse/Context.h>
+#include <pddlparse/detail/ASTContext.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Requirements
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool hasRequirement(const ast::Domain &domain, ast::Requirement requirement);
+bool hasRequirement(const ast::Problem &problem, ast::Requirement requirement);
+bool hasRequirement(const ASTContext &astContext, ast::Requirement requirement);
+
+void checkRequirement(ast::Domain &domain, ast::Requirement requirement, Context &context);
+void checkRequirement(ast::Problem &problem, ast::Requirement requirement, Context &context);
+void checkRequirement(ASTContext &astContext, ast::Requirement requirement, Context &context);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/AST.h b/lib/pddlparse/include/pddlparse/detail/parsing/AST.h
new file mode 100644
index 0000000..e6e12a6
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/AST.h
@@ -0,0 +1,127 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__AST_H
+#define __PDDL_PARSE__DETAIL__PARSING__AST_H
+
+#include <pddlparse/AST.h>
+#include <pddlparse/detail/parsing/Parser.h>
+#include <pddlparse/detail/parsing/Utils.h>
+
+namespace pddl
+{
+namespace detail
+{
+/*
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ParseAST
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Primitives
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<>
+struct Parser<ast::Constant>
+{
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<>
+struct Parser<ast::ConstantDeclaration>
+{
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<>
+struct Parser<ast::PrimitiveType>
+{
+	std::experimental::optional<ast::PrimitiveType> parse(Context &context, ASTContext &astContext)
+	{
+		auto &tokenizer = context.tokenizer;
+		auto &types = astContext.description.domain.types;
+
+		tokenizer.skipWhiteSpace();
+
+		auto typeName = tokenizer.getIdentifier();
+
+		if (typeName.empty())
+			throw tokenize::TokenizerException(tokenizer.location(), "no type supplied");
+
+		auto matchingType = std::find_if(types.begin(), types.end(),
+			[&](auto &primitiveTypeDeclaration)
+			{
+				return primitiveTypeDeclaration->name == typeName;
+			});
+
+		if (matchingType == types.end())
+		{
+			// Only “object” is allowed as an implicit type
+			if (typeName == "object" || typeName == "objects")
+			{
+				context.warningCallback(tokenizer.location(), "primitive type “" + typeName + "” should be declared");
+				types.emplace_back(std::make_unique<ast::PrimitiveTypeDeclaration>(std::move(typeName)));
+
+				return ast::PrimitiveType(types.back());
+			}
+			else
+				throw tokenize::TokenizerException(tokenizer.location(), "type “" + typeName + "” used but never declared");
+		}
+
+		auto &type = *matchingType;
+
+		return ast::PrimitiveType(type);
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<>
+struct Parser<ast::PrimitiveTypeDeclaration>
+{
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<>
+struct Parser<ast::Unsupported>
+{
+	std::experimental::optional<ast::Unsupported> parse(Context &context, ASTContext &)
+	{
+		auto &tokenizer = context.tokenizer;
+
+		ast::Unsupported unsupported;
+
+		tokenizer.expect<std::string>("(");
+
+		unsupported.type = tokenizer.getIdentifier();
+
+		context.warningCallback(tokenizer.location(), "expression type “" + unsupported.type + "” currently unsupported in this context");
+
+		skipSection(tokenizer);
+
+		return unsupported;
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+// Expressions
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Argument>
+struct Parser<ast::And<Argument>>
+{
+	template<typename ArgumentParser>
+	std::experimental::optional<ast::And<Argument>> parse(Context &context, ASTContext &astContext, ArgumentParser parseArgument)
+	{
+		return Parser<ast::NAry<ast::And<Argument>, Argument>>::parse(context, astContext, parseArgument);
+	}
+};
+*/
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Action.h b/lib/pddlparse/include/pddlparse/detail/parsing/Action.h
new file mode 100644
index 0000000..dff8ad5
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Action.h
@@ -0,0 +1,25 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__ACTION_H
+#define __PDDL_PARSE__DETAIL__PARSING__ACTION_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Action
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddAction(Context &context, ast::Domain &domain);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Constant.h b/lib/pddlparse/include/pddlparse/detail/parsing/Constant.h
new file mode 100644
index 0000000..b62b25a
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Constant.h
@@ -0,0 +1,26 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__CONSTANT_H
+#define __PDDL_PARSE__DETAIL__PARSING__CONSTANT_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Constant
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::ConstantPointer parseConstant(Context &context, ast::Domain &domain);
+ast::ConstantPointer parseConstant(Context &context, ast::Problem &problem);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/ConstantDeclaration.h b/lib/pddlparse/include/pddlparse/detail/parsing/ConstantDeclaration.h
new file mode 100644
index 0000000..a39dbca
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/ConstantDeclaration.h
@@ -0,0 +1,26 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__CONSTANT_DECLARATION_H
+#define __PDDL_PARSE__DETAIL__PARSING__CONSTANT_DECLARATION_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ConstantDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddConstantDeclarations(Context &context, ast::Domain &domain);
+void parseAndAddConstantDeclarations(Context &context, ast::Problem &problem);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Description.h b/lib/pddlparse/include/pddlparse/detail/parsing/Description.h
new file mode 100644
index 0000000..9ca20aa
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Description.h
@@ -0,0 +1,39 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__DESCRIPTION_H
+#define __PDDL_PARSE__DETAIL__PARSING__DESCRIPTION_H
+
+#include <experimental/optional>
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Description
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class DescriptionParser
+{
+	public:
+		DescriptionParser(Context &context);
+		ast::Description parse();
+
+	private:
+		void findSections();
+
+		Context &m_context;
+		tokenize::Stream::Position m_domainPosition;
+		tokenize::Stream::Position m_problemPosition;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Domain.h b/lib/pddlparse/include/pddlparse/detail/parsing/Domain.h
new file mode 100644
index 0000000..e86e62b
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Domain.h
@@ -0,0 +1,50 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__DOMAIN_H
+#define __PDDL_PARSE__DETAIL__PARSING__DOMAIN_H
+
+#include <experimental/optional>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Domain
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class DomainParser
+{
+	public:
+		DomainParser(Context &context);
+		ast::DomainPointer parse();
+
+	private:
+		void findSections(ast::Domain &domain);
+
+		void parseRequirementSection(ast::Domain &domain);
+		void computeDerivedRequirements(ast::Domain &domain);
+		void parseTypeSection(ast::Domain &domain);
+		void parseConstantSection(ast::Domain &domain);
+		void parsePredicateSection(ast::Domain &domain);
+		void parseActionSection(ast::Domain &domain);
+
+		Context &m_context;
+
+		tokenize::Stream::Position m_requirementsPosition;
+		tokenize::Stream::Position m_typesPosition;
+		tokenize::Stream::Position m_constantsPosition;
+		tokenize::Stream::Position m_predicatesPosition;
+		std::vector<tokenize::Stream::Position> m_actionPositions;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/InitialState.h b/lib/pddlparse/include/pddlparse/detail/parsing/InitialState.h
new file mode 100644
index 0000000..10afbe2
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/InitialState.h
@@ -0,0 +1,25 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__INITIAL_STATE_H
+#define __PDDL_PARSE__DETAIL__PARSING__INITIAL_STATE_H
+
+#include <pddlparse/Context.h>
+#include <pddlparse/detail/ASTContext.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// InitialState
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::InitialState parseInitialState(Context &context, ASTContext &expressionContext);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Parser.h b/lib/pddlparse/include/pddlparse/detail/parsing/Parser.h
new file mode 100644
index 0000000..81832a9
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Parser.h
@@ -0,0 +1,43 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSER_H
+#define __PDDL_PARSE__DETAIL__PARSER_H
+
+#include <experimental/optional>
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+#include <pddlparse/detail/ASTContext.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Parser
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class T>
+struct Parser
+{
+};
+
+template<class T, typename... ArgumentParser>
+std::experimental::optional<T> parse(Context &context, ASTContext &astContext, ArgumentParser... argumentParsers)
+{
+	return detail::Parser<T>().parse(context, astContext, argumentParsers...);
+}
+
+template<class T>
+std::experimental::optional<T> parse(Context &context, ASTContext &astContext)
+{
+	return detail::Parser<T>().parse(context, astContext);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/PredicateDeclaration.h b/lib/pddlparse/include/pddlparse/detail/parsing/PredicateDeclaration.h
new file mode 100644
index 0000000..e891433
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/PredicateDeclaration.h
@@ -0,0 +1,25 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__PREDICATE_DECLARATION_H
+#define __PDDL_PARSE__DETAIL__PARSING__PREDICATE_DECLARATION_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PredicateDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddPredicateDeclarations(Context &context, ast::Domain &domain);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/PrimitiveType.h b/lib/pddlparse/include/pddlparse/detail/parsing/PrimitiveType.h
new file mode 100644
index 0000000..6ad1406
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/PrimitiveType.h
@@ -0,0 +1,25 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__PRIMITIVE_TYPE_H
+#define __PDDL_PARSE__DETAIL__PARSING__PRIMITIVE_TYPE_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PrimitiveType
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::PrimitiveTypePointer parsePrimitiveType(Context &context, ast::Domain &domain);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/PrimitiveTypeDeclaration.h b/lib/pddlparse/include/pddlparse/detail/parsing/PrimitiveTypeDeclaration.h
new file mode 100644
index 0000000..85384c3
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/PrimitiveTypeDeclaration.h
@@ -0,0 +1,25 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__PRIMITIVE_TYPE_DECLARATION_H
+#define __PDDL_PARSE__DETAIL__PARSING__PRIMITIVE_TYPE_DECLARATION_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PrimitiveTypeDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddPrimitiveTypeDeclarations(Context &context, ast::Domain &domain);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Problem.h b/lib/pddlparse/include/pddlparse/detail/parsing/Problem.h
new file mode 100644
index 0000000..110c241
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Problem.h
@@ -0,0 +1,51 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__PROBLEM_H
+#define __PDDL_PARSE__DETAIL__PARSING__PROBLEM_H
+
+#include <experimental/optional>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Problem
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+class ProblemParser
+{
+	public:
+		ProblemParser(Context &context, ast::Domain &domain);
+		ast::ProblemPointer parse();
+
+	private:
+		void findSections(ast::Problem &problem);
+
+		void parseDomainSection(ast::Problem &problem);
+		void parseRequirementSection(ast::Problem &problem);
+		void computeDerivedRequirements(ast::Problem &problem);
+		void parseObjectSection(ast::Problem &problem);
+		void parseInitialStateSection(ast::Problem &problem);
+		void parseGoalSection(ast::Problem &problem);
+
+		Context &m_context;
+		ast::Domain &m_domain;
+
+		tokenize::Stream::Position m_domainPosition;
+		tokenize::Stream::Position m_requirementsPosition;
+		tokenize::Stream::Position m_objectsPosition;
+		tokenize::Stream::Position m_initialStatePosition;
+		tokenize::Stream::Position m_goalPosition;
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Requirement.h b/lib/pddlparse/include/pddlparse/detail/parsing/Requirement.h
new file mode 100644
index 0000000..40bb71f
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Requirement.h
@@ -0,0 +1,26 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__REQUIREMENT_H
+#define __PDDL_PARSE__DETAIL__PARSING__REQUIREMENT_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Requirement
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::Requirement parseRequirement(Context &context);
+const char *toString(const ast::Requirement &requirement);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/Variable.h b/lib/pddlparse/include/pddlparse/detail/parsing/Variable.h
new file mode 100644
index 0000000..5348813
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/Variable.h
@@ -0,0 +1,25 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__VARIABLE_H
+#define __PDDL_PARSE__DETAIL__PARSING__VARIABLE_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Variable
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::Variable parseVariable(Context &context, ast::Domain &domain);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/include/pddlparse/detail/parsing/VariableDeclaration.h b/lib/pddlparse/include/pddlparse/detail/parsing/VariableDeclaration.h
new file mode 100644
index 0000000..4952613
--- /dev/null
+++ b/lib/pddlparse/include/pddlparse/detail/parsing/VariableDeclaration.h
@@ -0,0 +1,25 @@
+#ifndef __PDDL_PARSE__DETAIL__PARSING__VARIABLE_DECLARATION_H
+#define __PDDL_PARSE__DETAIL__PARSING__VARIABLE_DECLARATION_H
+
+#include <pddlparse/ASTForward.h>
+#include <pddlparse/Context.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// VariableDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::VariableDeclarations parseVariableDeclarations(Context &context, ast::Domain &domain);
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
+
+#endif
diff --git a/lib/pddlparse/src/CMakeLists.txt b/lib/pddlparse/src/CMakeLists.txt
index 372b4b4..5596a5e 100644
--- a/lib/pddlparse/src/CMakeLists.txt
+++ b/lib/pddlparse/src/CMakeLists.txt
@@ -12,6 +12,7 @@ file(GLOB detail_parsing_headers "../include/pddlparse/detail/parsing/*.h")
 set(includes
 	${PROJECT_SOURCE_DIR}/include
 	${PROJECT_SOURCE_DIR}/../../lib/tokenize/include
+	${PROJECT_SOURCE_DIR}/../../lib/variant/include
 )
 
 set(sources
diff --git a/lib/pddlparse/src/pddlparse/Parse.cpp b/lib/pddlparse/src/pddlparse/Parse.cpp
new file mode 100644
index 0000000..e4edaf8
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/Parse.cpp
@@ -0,0 +1,22 @@
+#include <pddlparse/Parse.h>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/detail/parsing/Description.h>
+
+namespace pddl
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Parse
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::Description parseDescription(Context &context)
+{
+	return detail::DescriptionParser(context).parse();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/Requirements.cpp b/lib/pddlparse/src/pddlparse/detail/Requirements.cpp
new file mode 100644
index 0000000..4b9980c
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/Requirements.cpp
@@ -0,0 +1,92 @@
+#include <pddlparse/detail/Requirements.h>
+
+#include <algorithm>
+
+#include <pddlparse/detail/parsing/Requirement.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Requirements
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool hasRequirement(const ast::Domain &domain, ast::Requirement requirement)
+{
+	const auto match = std::find_if(domain.requirements.cbegin(), domain.requirements.cend(),
+		[&](const auto &declaredRequirement)
+		{
+			return declaredRequirement == requirement;
+		});
+
+	return match != domain.requirements.cend();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool hasRequirement(const ast::Problem &problem, ast::Requirement requirement)
+{
+	const auto match = std::find_if(problem.requirements.cbegin(), problem.requirements.cend(),
+		[&](const auto &declaredRequirement)
+		{
+			return declaredRequirement == requirement;
+		});
+
+	if (match != problem.requirements.cend())
+		return true;
+
+	return hasRequirement(problem.domain, requirement);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+bool hasRequirement(const ASTContext &astContext, ast::Requirement requirement)
+{
+	if (astContext.problem)
+		return hasRequirement(*astContext.problem.value(), requirement);
+
+	return hasRequirement(*astContext.domain, requirement);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void checkRequirement(ast::Domain &domain, ast::Requirement requirement, Context &context)
+{
+	if (hasRequirement(domain, requirement))
+		return;
+
+	context.warningCallback(context.tokenizer.location(), "requirement “" + std::string(toString(requirement)) + "” used but never declared");
+
+	domain.requirements.push_back(requirement);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void checkRequirement(ast::Problem &problem, ast::Requirement requirement, Context &context)
+{
+	if (hasRequirement(problem, requirement))
+		return;
+
+	context.warningCallback(context.tokenizer.location(), "requirement “" + std::string(toString(requirement)) + "” used but never declared");
+
+	problem.requirements.push_back(requirement);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void checkRequirement(ASTContext &astContext, ast::Requirement requirement, Context &context)
+{
+	if (astContext.problem)
+		checkRequirement(*astContext.problem.value(), requirement, context);
+	else
+		checkRequirement(*astContext.domain, requirement, context);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/Action.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/Action.cpp
new file mode 100644
index 0000000..c060bdf
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/Action.cpp
@@ -0,0 +1,68 @@
+#include <pddlparse/detail/parsing/Action.h>
+
+#include <pddlparse/AST.h>
+// TODO: remove
+#include <pddlparse/detail/parsing/Utils.h>
+#include <pddlparse/detail/parsing/VariableDeclaration.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Action
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddAction(Context &context, ast::Domain &domain)
+{
+	auto &tokenizer = context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("action");
+
+	auto action = std::make_unique<ast::Action>();
+	action->name = tokenizer.getIdentifier();
+
+	tokenizer.expect<std::string>(":parameters");
+	tokenizer.expect<std::string>("(");
+
+	// Read parameters
+	action->parameters = parseVariableDeclarations(context, domain);
+
+	tokenizer.expect<std::string>(")");
+
+	// TODO: reimplement
+	skipSection(tokenizer);
+
+	/*
+	// Parse preconditions and effects
+	while (!tokenizer.testAndReturn(')'))
+	{
+		tokenizer.expect<std::string>(":");
+
+		if (tokenizer.testIdentifierAndSkip("precondition"))
+			// TODO: reimplement
+			//action->precondition = parsePreconditionExpression(context, expressionContext);
+			skipSection(tokenizer);
+		else if (tokenizer.testIdentifierAndSkip("effect"))
+			// TODO: reimplement
+			//action->effect = parseEffectExpression(context, expressionContext);
+			skipSection(tokenizer);
+
+		tokenizer.skipWhiteSpace();
+	}*/
+
+	// Store new action
+	domain.actions.emplace_back(std::move(action));
+
+	//tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/Constant.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/Constant.cpp
new file mode 100644
index 0000000..d518438
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/Constant.cpp
@@ -0,0 +1,69 @@
+#include <pddlparse/detail/parsing/Constant.h>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/ParserException.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Constant
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+std::experimental::optional<ast::ConstantPointer> findConstant(const std::string &constantName, ast::ConstantDeclarations &constantDeclarations)
+{
+	const auto matchingConstant = std::find_if(constantDeclarations.begin(), constantDeclarations.end(),
+		[&](const auto &constantDeclaration)
+		{
+			return constantDeclaration->name == constantName;
+		});
+
+	if (matchingConstant == constantDeclarations.end())
+		return std::experimental::nullopt;
+
+	return std::make_unique<ast::Constant>(matchingConstant->get());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::ConstantPointer parseConstant(Context &context, ast::Domain &domain)
+{
+	auto &tokenizer = context.tokenizer;
+	const auto constantName = tokenizer.getIdentifier();
+
+	auto constant = findConstant(constantName, domain.constants);
+
+	if (constant)
+		return std::move(constant.value());
+
+	throw ParserException(tokenizer.location(), "constant “" + constantName + "” used but never declared");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::ConstantPointer parseConstant(Context &context, ast::Problem &problem)
+{
+	auto &tokenizer = context.tokenizer;
+	const auto constantName = tokenizer.getIdentifier();
+
+	auto constant = findConstant(constantName, problem.domain->constants);
+
+	if (constant)
+		return std::move(constant.value());
+
+	auto object = findConstant(constantName, problem.objects);
+
+	if (object)
+		return std::move(object.value());
+
+	throw ParserException(tokenizer.location(), "constant “" + constantName + "” used but never declared");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/ConstantDeclaration.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/ConstantDeclaration.cpp
new file mode 100644
index 0000000..a1c3196
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/ConstantDeclaration.cpp
@@ -0,0 +1,78 @@
+#include <pddlparse/detail/parsing/ConstantDeclaration.h>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/ASTCopy.h>
+#include <pddlparse/detail/parsing/PrimitiveType.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// ConstantDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddUntypedConstantDeclaration(Context &context, ast::ConstantDeclarations &constantDeclarations)
+{
+	auto &tokenizer = context.tokenizer;
+	auto constantName = tokenizer.getIdentifier();
+
+	assert(constantName != "-");
+
+	constantDeclarations.emplace_back(std::make_unique<ast::ConstantDeclaration>(std::move(constantName)));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddConstantDeclarations(Context &context, ast::Domain &domain, ast::ConstantDeclarations &constantDeclarations)
+{
+	auto &tokenizer = context.tokenizer;
+	tokenizer.skipWhiteSpace();
+
+	// Index on the first element of the current inheritance list
+	size_t inheritanceIndex = 0;
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		parseAndAddUntypedConstantDeclaration(context, constantDeclarations);
+
+		tokenizer.skipWhiteSpace();
+
+		if (!tokenizer.testAndSkip<char>('-'))
+			continue;
+
+		// If existing, parse and store parent type
+		auto parentType = parsePrimitiveType(context, domain);
+
+		for (size_t i = inheritanceIndex; i < constantDeclarations.size(); i++)
+			constantDeclarations[i]->type = ast::deepCopy(parentType);
+
+		// All types up to now are labeled with their parent types
+		inheritanceIndex = constantDeclarations.size() + 1;
+
+		tokenizer.skipWhiteSpace();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddConstantDeclarations(Context &context, ast::Domain &domain)
+{
+	parseAndAddConstantDeclarations(context, domain, domain.constants);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddConstantDeclarations(Context &context, ast::Problem &problem)
+{
+	parseAndAddConstantDeclarations(context, *problem.domain, problem.objects);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/Description.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/Description.cpp
new file mode 100644
index 0000000..b7ded73
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/Description.cpp
@@ -0,0 +1,107 @@
+#include <pddlparse/detail/parsing/Description.h>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/parsing/Domain.h>
+#include <pddlparse/detail/parsing/Problem.h>
+#include <pddlparse/detail/parsing/Utils.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Description
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+DescriptionParser::DescriptionParser(Context &context)
+:	m_context{context},
+	m_domainPosition{-1},
+	m_problemPosition{-1}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::Description DescriptionParser::parse()
+{
+	auto &tokenizer = m_context.tokenizer;
+	tokenizer.removeComments(";", "\n", false);
+
+	findSections();
+
+	if (m_domainPosition == -1)
+		throw ParserException("no PDDL domain specified");
+
+	tokenizer.seek(m_domainPosition);
+
+	auto domain = DomainParser(m_context).parse();
+
+	// If no problem is given, return just the domain
+	if (m_problemPosition == -1)
+		return {std::move(domain), std::experimental::nullopt};
+
+	tokenizer.seek(m_problemPosition);
+
+	auto problem = ProblemParser(m_context, *domain).parse();
+
+	// TODO: check consistency
+	// * check typing requirement
+	// * check that typing is used consistently
+	// * check that constants, variables, and predicates aren't declared twice
+	// * check section order
+	// * check that preconditions and effects are well-formed
+	return {std::move(domain), std::move(problem)};
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DescriptionParser::findSections()
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.skipWhiteSpace();
+
+	while (!tokenizer.atEnd())
+	{
+		const auto position = tokenizer.position();
+
+		tokenizer.expect<std::string>("(");
+		tokenizer.expect<std::string>("define");
+		tokenizer.expect<std::string>("(");
+
+		if (tokenizer.testAndSkip<std::string>("domain"))
+		{
+			if (m_domainPosition != -1)
+				throw ParserException(tokenizer.location(), "PDDL description may not contain two domains");
+
+			m_domainPosition = position;
+			skipSection(tokenizer);
+			skipSection(tokenizer);
+		}
+		else if (m_context.tokenizer.testAndSkip<std::string>("problem"))
+		{
+			if (m_problemPosition != -1)
+				throw ParserException("PDDL description may not contain two problems currently");
+
+			m_problemPosition = position;
+			skipSection(tokenizer);
+			skipSection(tokenizer);
+		}
+		else
+		{
+			const auto sectionIdentifier = tokenizer.get<std::string>();
+			throw ParserException(tokenizer.location(), "unknown PDDL section “" + sectionIdentifier + "”");
+		}
+
+		tokenizer.skipWhiteSpace();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/Domain.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/Domain.cpp
new file mode 100644
index 0000000..5351c21
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/Domain.cpp
@@ -0,0 +1,300 @@
+#include <pddlparse/detail/parsing/Domain.h>
+
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/Requirements.h>
+#include <pddlparse/detail/parsing/Action.h>
+#include <pddlparse/detail/parsing/ConstantDeclaration.h>
+#include <pddlparse/detail/parsing/PredicateDeclaration.h>
+#include <pddlparse/detail/parsing/PrimitiveTypeDeclaration.h>
+#include <pddlparse/detail/parsing/Requirement.h>
+#include <pddlparse/detail/parsing/Utils.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Domain
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+DomainParser::DomainParser(Context &context)
+:	m_context{context},
+	m_requirementsPosition{-1},
+	m_typesPosition{-1},
+	m_constantsPosition{-1},
+	m_predicatesPosition{-1}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::DomainPointer DomainParser::parse()
+{
+	auto domain = std::make_unique<ast::Domain>();
+
+	findSections(*domain);
+
+	auto &tokenizer = m_context.tokenizer;
+
+	if (m_requirementsPosition != -1)
+	{
+		tokenizer.seek(m_requirementsPosition);
+		parseRequirementSection(*domain);
+	}
+
+	if (m_typesPosition != -1)
+	{
+		tokenizer.seek(m_typesPosition);
+		parseTypeSection(*domain);
+	}
+
+	if (m_constantsPosition != -1)
+	{
+		tokenizer.seek(m_constantsPosition);
+		parseConstantSection(*domain);
+	}
+
+	if (m_predicatesPosition != -1)
+	{
+		tokenizer.seek(m_predicatesPosition);
+		parsePredicateSection(*domain);
+	}
+
+	for (size_t i = 0; i < m_actionPositions.size(); i++)
+		if (m_actionPositions[i] != -1)
+		{
+			tokenizer.seek(m_actionPositions[i]);
+			parseActionSection(*domain);
+		}
+
+	computeDerivedRequirements(*domain);
+
+	return domain;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DomainParser::findSections(ast::Domain &domain)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>("define");
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>("domain");
+
+	domain.name = tokenizer.getIdentifier();
+
+	tokenizer.expect<std::string>(")");
+
+	const auto setSectionPosition =
+		[&](const std::string &sectionName, auto &sectionPosition, const auto value, bool unique = false)
+		{
+			if (unique && sectionPosition != -1)
+			{
+				tokenizer.seek(value);
+				throw tokenize::TokenizerException(tokenizer.location(), "only one “:" + sectionName + "” section allowed");
+			}
+
+			sectionPosition = value;
+		};
+
+	tokenizer.skipWhiteSpace();
+
+	// Find sections
+	while (tokenizer.currentCharacter() != ')')
+	{
+		const auto position = tokenizer.position();
+
+		tokenizer.expect<std::string>("(");
+		tokenizer.expect<std::string>(":");
+
+		const auto sectionIdentifierPosition = tokenizer.position();
+
+		// Save the parser position of the individual sections for later parsing
+		if (tokenizer.testIdentifierAndSkip("requirements"))
+			setSectionPosition("requirements", m_requirementsPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("types"))
+			setSectionPosition("types", m_typesPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("constants"))
+			setSectionPosition("constants", m_constantsPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("predicates"))
+			setSectionPosition("predicates", m_predicatesPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("action"))
+		{
+			m_actionPositions.emplace_back(-1);
+			setSectionPosition("action", m_actionPositions.back(), position);
+		}
+		else if (tokenizer.testIdentifierAndSkip("functions")
+			|| tokenizer.testIdentifierAndSkip("constraints")
+			|| tokenizer.testIdentifierAndSkip("durative-action")
+			|| tokenizer.testIdentifierAndSkip("derived"))
+		{
+			tokenizer.seek(sectionIdentifierPosition);
+
+			const auto sectionIdentifier = tokenizer.getIdentifier();
+
+			m_context.warningCallback(tokenizer.location(), "section type “" + sectionIdentifier + "” currently unsupported");
+
+			tokenizer.seek(sectionIdentifierPosition);
+		}
+		else
+		{
+			const auto sectionIdentifier = tokenizer.getIdentifier();
+
+			tokenizer.seek(position);
+			throw tokenize::TokenizerException(tokenizer.location(), "unknown domain section “" + sectionIdentifier + "”");
+		}
+
+		// Skip section for now and parse it later
+		skipSection(tokenizer);
+
+		tokenizer.skipWhiteSpace();
+	}
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DomainParser::parseRequirementSection(ast::Domain &domain)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("requirements");
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		tokenizer.expect<std::string>(":");
+
+		domain.requirements.emplace_back(parseRequirement(m_context));
+
+		tokenizer.skipWhiteSpace();
+	}
+
+	// TODO: do this check only once the problem is parsed
+	// If no requirements are specified, assume STRIPS
+	if (domain.requirements.empty())
+		domain.requirements.emplace_back(ast::Requirement::STRIPS);
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DomainParser::computeDerivedRequirements(ast::Domain &domain)
+{
+	const auto addRequirementUnique =
+		[&](auto requirement)
+		{
+			if (hasRequirement(domain, requirement))
+				return;
+
+			domain.requirements.push_back(requirement);
+		};
+
+	if (hasRequirement(domain, ast::Requirement::ADL))
+	{
+		addRequirementUnique(ast::Requirement::STRIPS);
+		addRequirementUnique(ast::Requirement::Typing);
+		addRequirementUnique(ast::Requirement::NegativePreconditions);
+		addRequirementUnique(ast::Requirement::DisjunctivePreconditions);
+		addRequirementUnique(ast::Requirement::Equality);
+		addRequirementUnique(ast::Requirement::QuantifiedPreconditions);
+		addRequirementUnique(ast::Requirement::ConditionalEffects);
+	}
+
+	if (hasRequirement(domain, ast::Requirement::QuantifiedPreconditions))
+	{
+		addRequirementUnique(ast::Requirement::ExistentialPreconditions);
+		addRequirementUnique(ast::Requirement::UniversalPreconditions);
+	}
+
+	if (hasRequirement(domain, ast::Requirement::Fluents))
+	{
+		addRequirementUnique(ast::Requirement::NumericFluents);
+		addRequirementUnique(ast::Requirement::ObjectFluents);
+	}
+
+	if (hasRequirement(domain, ast::Requirement::TimedInitialLiterals))
+		addRequirementUnique(ast::Requirement::DurativeActions);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DomainParser::parseTypeSection(ast::Domain &domain)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("types");
+
+	checkRequirement(domain, ast::Requirement::Typing, m_context);
+
+	tokenizer.skipWhiteSpace();
+
+	// Store types and their parent types
+	while (tokenizer.currentCharacter() != ')')
+	{
+		if (tokenizer.currentCharacter() == '(')
+			throw ParserException(tokenizer.location(), "only primitive types are allowed in type section");
+
+		parseAndAddPrimitiveTypeDeclarations(m_context, domain);
+
+		tokenizer.skipWhiteSpace();
+	}
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DomainParser::parseConstantSection(ast::Domain &domain)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("constants");
+
+	// Store constants
+	parseAndAddConstantDeclarations(m_context, domain);
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DomainParser::parsePredicateSection(ast::Domain &domain)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("predicates");
+
+	tokenizer.skipWhiteSpace();
+
+	// Store predicates
+	parseAndAddPredicateDeclarations(m_context, domain);
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void DomainParser::parseActionSection(ast::Domain &domain)
+{
+	parseAndAddAction(m_context, domain);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/InitialState.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/InitialState.cpp
new file mode 100644
index 0000000..868756e
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/InitialState.cpp
@@ -0,0 +1,79 @@
+#include <pddlparse/detail/parsing/InitialState.h>
+
+#include <pddlparse/AST.h>
+// TODO: remove
+#include <pddlparse/detail/parsing/Utils.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// InitialState
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::InitialState parseInitialState(Context &context, ASTContext &)
+{
+	auto &tokenizer = context.tokenizer;
+
+	ast::InitialState initialState;
+
+	// TODO: reimplement
+	/*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 = tokenizer.position();
+
+			tokenizer.expect<std::string>("(");
+
+			const auto expressionIdentifierPosition = tokenizer.position();
+
+			if (tokenizer.testIdentifierAndSkip("="))
+			{
+				tokenizer.seek(expressionIdentifierPosition);
+				const auto expressionIdentifier = tokenizer.getIdentifier();
+
+				tokenizer.seek(position);
+				return expressions::Unsupported::parse(context);
+			}
+
+			tokenizer.seek(expressionIdentifierPosition);
+			const auto expressionIdentifier = tokenizer.getIdentifier();
+
+			tokenizer.seek(position);
+			throw tokenize::TokenizerException(tokenizer.location(), "expression type “" + expressionIdentifier + "” unknown or not allowed in this context");
+		};
+
+	tokenizer.skipWhiteSpace();
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		ast::Expression expression;
+
+		if ((expression = parseInitialStateElement()))
+			initialState->m_facts.emplace_back(std::move(expression));
+
+		tokenizer.skipWhiteSpace();
+	}*/
+
+	skipSection(tokenizer);
+
+	return initialState;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/PredicateDeclaration.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/PredicateDeclaration.cpp
new file mode 100644
index 0000000..b5291b2
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/PredicateDeclaration.cpp
@@ -0,0 +1,53 @@
+#include <pddlparse/detail/parsing/PredicateDeclaration.h>
+
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/ASTContext.h>
+#include <pddlparse/detail/parsing/VariableDeclaration.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PredicateDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddPredicateDeclaration(Context &context, ast::Domain &domain)
+{
+	auto &tokenizer = context.tokenizer;
+	tokenizer.expect<std::string>("(");
+
+	auto name = tokenizer.getIdentifier();
+
+	tokenizer.skipWhiteSpace();
+
+	// Parse parameters
+	auto parameters = parseVariableDeclarations(context, domain);
+
+	tokenizer.expect<std::string>(")");
+
+	domain.predicates.emplace_back(std::make_unique<ast::PredicateDeclaration>(std::move(name), std::move(parameters)));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddPredicateDeclarations(Context &context, ast::Domain &domain)
+{
+	auto &tokenizer = context.tokenizer;
+	tokenizer.skipWhiteSpace();
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		parseAndAddPredicateDeclaration(context, domain);
+
+		tokenizer.skipWhiteSpace();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/PrimitiveType.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/PrimitiveType.cpp
new file mode 100644
index 0000000..1ffd915
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/PrimitiveType.cpp
@@ -0,0 +1,55 @@
+#include <pddlparse/detail/parsing/PrimitiveType.h>
+
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/Requirements.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PrimitiveType
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::PrimitiveTypePointer parsePrimitiveType(Context &context, ast::Domain &domain)
+{
+	auto &tokenizer = context.tokenizer;
+	auto &types = domain.types;
+
+	tokenizer.skipWhiteSpace();
+
+	auto typeName = tokenizer.getIdentifier();
+
+	if (typeName.empty())
+		throw tokenize::TokenizerException(tokenizer.location(), "no type supplied");
+
+	auto matchingType = std::find_if(types.begin(), types.end(),
+		[&](auto &primitiveTypeDeclaration)
+		{
+			return primitiveTypeDeclaration->name == typeName;
+		});
+
+	if (matchingType == types.end())
+	{
+		// Only “object” is allowed as an implicit type
+		if (typeName == "object" || typeName == "objects")
+		{
+			context.warningCallback(tokenizer.location(), "primitive type “" + typeName + "” should be declared");
+			types.emplace_back(std::make_unique<ast::PrimitiveTypeDeclaration>(std::move(typeName)));
+
+			return std::make_unique<ast::PrimitiveType>(types.back().get());
+		}
+		else
+			throw tokenize::TokenizerException(tokenizer.location(), "type “" + typeName + "” used but never declared");
+	}
+
+	return std::make_unique<ast::PrimitiveType>(matchingType->get());
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/PrimitiveTypeDeclaration.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/PrimitiveTypeDeclaration.cpp
new file mode 100644
index 0000000..ae22764
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/PrimitiveTypeDeclaration.cpp
@@ -0,0 +1,77 @@
+#include <pddlparse/detail/parsing/PrimitiveTypeDeclaration.h>
+
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/ASTCopy.h>
+#include <pddlparse/detail/parsing/PrimitiveType.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// PrimitiveTypeDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::PrimitiveTypeDeclarationPointer &parseAndAddUntypedPrimitiveTypeDeclaration(Context &context, ast::Domain &domain)
+{
+	auto &tokenizer = context.tokenizer;
+	auto typeName = tokenizer.getIdentifier();
+
+	auto &types = domain.types;
+
+	const auto matchingPrimitiveType = std::find_if(types.begin(), types.end(),
+		[&](const auto &primitiveType)
+		{
+			return primitiveType->name == typeName;
+		});
+
+	// Return existing primitive type
+	if (matchingPrimitiveType != types.cend())
+		return *matchingPrimitiveType;
+
+	types.emplace_back(std::make_unique<ast::PrimitiveTypeDeclaration>(std::move(typeName)));
+
+	return types.back();
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddPrimitiveTypeDeclarations(Context &context, ast::Domain &domain)
+{
+	auto &tokenizer = context.tokenizer;
+	tokenizer.skipWhiteSpace();
+
+	// Index on the first element of the current inheritance list
+	size_t inheritanceIndex = 0;
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		parseAndAddUntypedPrimitiveTypeDeclaration(context, domain);
+
+		tokenizer.skipWhiteSpace();
+
+		if (!tokenizer.testAndSkip<char>('-'))
+			continue;
+
+		// If existing, parse and store parent type
+		auto parentType = parsePrimitiveType(context, domain);
+
+		auto &types = domain.types;
+
+		for (size_t i = inheritanceIndex; i < types.size(); i++)
+			types[i]->parentTypes.emplace_back(ast::deepCopy(parentType));
+
+		// All types up to now are labeled with their parent types
+		inheritanceIndex = types.size() + 1;
+
+		tokenizer.skipWhiteSpace();
+	}
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/Problem.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/Problem.cpp
new file mode 100644
index 0000000..d577852
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/Problem.cpp
@@ -0,0 +1,297 @@
+#include <pddlparse/detail/parsing/Problem.h>
+
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/Requirements.h>
+#include <pddlparse/detail/parsing/ConstantDeclaration.h>
+#include <pddlparse/detail/parsing/InitialState.h>
+#include <pddlparse/detail/parsing/Requirement.h>
+#include <pddlparse/detail/parsing/Utils.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Problem
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ProblemParser::ProblemParser(Context &context, ast::Domain &domain)
+:	m_context{context},
+	m_domain{domain},
+	m_domainPosition{-1},
+	m_requirementsPosition{-1},
+	m_objectsPosition{-1},
+	m_initialStatePosition{-1},
+	m_goalPosition{-1}
+{
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::ProblemPointer ProblemParser::parse()
+{
+	auto problem = std::make_unique<ast::Problem>(&m_domain);
+
+	findSections(*problem);
+
+	auto &tokenizer = m_context.tokenizer;
+
+	if (m_domainPosition == -1)
+		throw ParserException(tokenizer.location(), "problem description does not specify a corresponding domain");
+
+	tokenizer.seek(m_domainPosition);
+	parseDomainSection(*problem);
+
+	if (m_requirementsPosition != -1)
+	{
+		tokenizer.seek(m_requirementsPosition);
+		parseRequirementSection(*problem);
+	}
+
+	if (m_objectsPosition != -1)
+	{
+		tokenizer.seek(m_objectsPosition);
+		parseObjectSection(*problem);
+	}
+
+	if (m_initialStatePosition == -1)
+		throw ParserException(tokenizer.location(), "problem description does not specify an initial state");
+
+	tokenizer.seek(m_initialStatePosition);
+	parseInitialStateSection(*problem);
+
+	if (m_goalPosition == -1)
+		throw ParserException(tokenizer.location(), "problem description does not specify a goal");
+
+	tokenizer.seek(m_goalPosition);
+	parseGoalSection(*problem);
+
+	return problem;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void ProblemParser::findSections(ast::Problem &problem)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>("define");
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>("problem");
+
+	problem.name = tokenizer.getIdentifier();
+
+	tokenizer.expect<std::string>(")");
+
+	const auto setSectionPosition =
+		[&](const std::string &sectionName, auto &sectionPosition, const auto value, bool unique = false)
+		{
+			if (unique && sectionPosition != -1)
+			{
+				tokenizer.seek(value);
+				throw tokenize::TokenizerException(tokenizer.location(), "only one “:" + sectionName + "” section allowed");
+			}
+
+			sectionPosition = value;
+		};
+
+	tokenizer.skipWhiteSpace();
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		const auto position = tokenizer.position();
+
+		tokenizer.expect<std::string>("(");
+		tokenizer.expect<std::string>(":");
+
+		const auto sectionIdentifierPosition = tokenizer.position();
+
+		if (tokenizer.testIdentifierAndSkip("domain"))
+			setSectionPosition("domain", m_domainPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("requirements"))
+			setSectionPosition("requirements", m_requirementsPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("objects"))
+			setSectionPosition("objects", m_objectsPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("init"))
+			setSectionPosition("init", m_initialStatePosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("goal"))
+			setSectionPosition("goal", m_goalPosition, position, true);
+		else if (tokenizer.testIdentifierAndSkip("constraints")
+			|| tokenizer.testIdentifierAndSkip("metric")
+			|| tokenizer.testIdentifierAndSkip("length"))
+		{
+			tokenizer.seek(sectionIdentifierPosition);
+
+			const auto sectionIdentifier = tokenizer.getIdentifier();
+
+			m_context.warningCallback(tokenizer.location(), "section type “" + sectionIdentifier + "” currently unsupported");
+
+			tokenizer.seek(sectionIdentifierPosition);
+		}
+		else
+		{
+			const auto sectionIdentifier = tokenizer.getIdentifier();
+
+			tokenizer.seek(position);
+			throw tokenize::TokenizerException(tokenizer.location(), "unknown problem section “" + sectionIdentifier + "”");
+		}
+
+		// Skip section for now and parse it later
+		skipSection(tokenizer);
+
+		tokenizer.skipWhiteSpace();
+	}
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void ProblemParser::parseDomainSection(ast::Problem &problem)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("domain");
+
+	tokenizer.skipWhiteSpace();
+
+	const auto domainName = tokenizer.getIdentifier();
+
+	if (problem.domain->name != domainName)
+		throw tokenize::TokenizerException(tokenizer.location(), "domains do not match (“" + problem.domain->name + "” and “" + domainName + "”)");
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void ProblemParser::parseRequirementSection(ast::Problem &problem)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("requirements");
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		tokenizer.expect<std::string>(":");
+
+		problem.requirements.emplace_back(parseRequirement(m_context));
+
+		tokenizer.skipWhiteSpace();
+	}
+
+	// TODO: do this check only once the problem is parsed
+	// If no requirements are specified, assume STRIPS
+	if (problem.requirements.empty())
+		problem.requirements.emplace_back(ast::Requirement::STRIPS);
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+// TODO: refactor, exists identically in DomainParser
+void ProblemParser::computeDerivedRequirements(ast::Problem &problem)
+{
+	const auto addRequirementUnique =
+		[&](const auto requirement)
+		{
+			if (hasRequirement(problem, requirement))
+				return;
+
+			problem.requirements.push_back(ast::Requirement(requirement));
+		};
+
+	if (hasRequirement(problem, ast::Requirement::ADL))
+	{
+		addRequirementUnique(ast::Requirement::STRIPS);
+		addRequirementUnique(ast::Requirement::Typing);
+		addRequirementUnique(ast::Requirement::NegativePreconditions);
+		addRequirementUnique(ast::Requirement::DisjunctivePreconditions);
+		addRequirementUnique(ast::Requirement::Equality);
+		addRequirementUnique(ast::Requirement::QuantifiedPreconditions);
+		addRequirementUnique(ast::Requirement::ConditionalEffects);
+	}
+
+	if (hasRequirement(problem, ast::Requirement::QuantifiedPreconditions))
+	{
+		addRequirementUnique(ast::Requirement::ExistentialPreconditions);
+		addRequirementUnique(ast::Requirement::UniversalPreconditions);
+	}
+
+	if (hasRequirement(problem, ast::Requirement::Fluents))
+	{
+		addRequirementUnique(ast::Requirement::NumericFluents);
+		addRequirementUnique(ast::Requirement::ObjectFluents);
+	}
+
+	if (hasRequirement(problem, ast::Requirement::TimedInitialLiterals))
+		addRequirementUnique(ast::Requirement::DurativeActions);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void ProblemParser::parseObjectSection(ast::Problem &problem)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("objects");
+
+	// Store constants
+	parseAndAddConstantDeclarations(m_context, problem);
+
+	tokenizer.expect<std::string>(")");
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void ProblemParser::parseInitialStateSection(ast::Problem &problem)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("init");
+
+	ASTContext astContext(problem);
+
+	// TODO: reimplement
+	//problem.initialState = parseInitialState(m_context, astContext);
+	//tokenizer.expect<std::string>(")");
+
+	skipSection(tokenizer);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void ProblemParser::parseGoalSection(ast::Problem &problem)
+{
+	auto &tokenizer = m_context.tokenizer;
+
+	tokenizer.expect<std::string>("(");
+	tokenizer.expect<std::string>(":");
+	tokenizer.expect<std::string>("goal");
+
+	ASTContext expressionContext(problem);
+
+	// TODO: reimplement
+	//problem.goal = parsePreconditionExpression(m_context, expressionContext);
+	//tokenizer.expect<std::string>(")");
+
+	skipSection(tokenizer);
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/Requirement.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/Requirement.cpp
new file mode 100644
index 0000000..fcc6375
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/Requirement.cpp
@@ -0,0 +1,102 @@
+#include <pddlparse/detail/parsing/Requirement.h>
+
+#include <cstring>
+#include <map>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/ParserException.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// Requirement
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+struct CompareStrings
+{
+	bool operator()(const char *lhs, const char *rhs) const
+	{
+		return std::strcmp(lhs, rhs) < 0;
+	}
+};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+using RequirementNameMap = std::map<const char *, ast::Requirement, CompareStrings>;
+static const RequirementNameMap requirementNameMap =
+	{
+		{"strips", ast::Requirement::STRIPS},
+		{"typing", ast::Requirement::Typing},
+		{"negative-preconditions", ast::Requirement::NegativePreconditions},
+		{"disjunctive-preconditions", ast::Requirement::DisjunctivePreconditions},
+		{"equality", ast::Requirement::Equality},
+		{"existential-preconditions", ast::Requirement::ExistentialPreconditions},
+		{"universal-preconditions", ast::Requirement::UniversalPreconditions},
+		{"quantified-preconditions", ast::Requirement::QuantifiedPreconditions},
+		{"conditional-effects", ast::Requirement::ConditionalEffects},
+		{"fluents", ast::Requirement::Fluents},
+		{"numeric-fluents", ast::Requirement::NumericFluents},
+		{"object-fluents", ast::Requirement::ObjectFluents},
+		{"adl", ast::Requirement::ADL},
+		{"durative-actions", ast::Requirement::DurativeActions},
+		{"duration-inequalities", ast::Requirement::DurationInequalities},
+		{"continuous-effects", ast::Requirement::ContinuousEffects},
+		{"derived-predicates", ast::Requirement::DerivedPredicates},
+		{"timed-initial-literals", ast::Requirement::TimedInitialLiterals},
+		{"preferences", ast::Requirement::Preferences},
+		{"constraints", ast::Requirement::Constraints},
+		{"action-costs", ast::Requirement::ActionCosts},
+		{"goal-utilities", ast::Requirement::GoalUtilities},
+	};
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::Requirement parseRequirement(Tokenizer &tokenizer)
+{
+	const auto requirementName = tokenizer.getIdentifier();
+	const auto matchingRequirement = requirementNameMap.find(requirementName.c_str());
+
+	if (matchingRequirement == requirementNameMap.cend())
+		throw ParserException(tokenizer.location(), "unknown PDDL requirement “" + requirementName + "”");
+
+	return matchingRequirement->second;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::Requirement parseRequirement(Context &context)
+{
+	auto &tokenizer = context.tokenizer;
+
+	auto requirement = parseRequirement(tokenizer);
+
+	if (requirement == ast::Requirement::GoalUtilities)
+		context.warningCallback(tokenizer.location(), "requirement “goal-utilities” is not part of the PDDL 3.1 specification");
+
+	return requirement;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+const char *toString(const ast::Requirement &requirement)
+{
+	const auto matchingRequirement = std::find_if(requirementNameMap.cbegin(), requirementNameMap.cend(),
+		[&](const auto &requirementNamePair)
+		{
+			return requirementNamePair.second == requirement;
+		});
+
+	assert(matchingRequirement != requirementNameMap.cend());
+
+	return matchingRequirement->first;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/src/pddlparse/detail/parsing/VariableDeclaration.cpp b/lib/pddlparse/src/pddlparse/detail/parsing/VariableDeclaration.cpp
new file mode 100644
index 0000000..811b233
--- /dev/null
+++ b/lib/pddlparse/src/pddlparse/detail/parsing/VariableDeclaration.cpp
@@ -0,0 +1,69 @@
+#include <pddlparse/detail/parsing/VariableDeclaration.h>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/ParserException.h>
+#include <pddlparse/detail/ASTCopy.h>
+#include <pddlparse/detail/parsing/PrimitiveType.h>
+
+namespace pddl
+{
+namespace detail
+{
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+//
+// VariableDeclaration
+//
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+void parseAndAddUntypedVariableDeclaration(Context &context, ast::VariableDeclarations &variableDeclarations)
+{
+	auto &tokenizer = context.tokenizer;
+	tokenizer.expect<std::string>("?");
+	auto variableName = tokenizer.getIdentifier();
+
+	assert(variableName != "-");
+
+	variableDeclarations.emplace_back(std::make_unique<ast::VariableDeclaration>(std::move(variableName)));
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ast::VariableDeclarations parseVariableDeclarations(Context &context, ast::Domain &domain)
+{
+	ast::VariableDeclarations variableDeclarations;
+
+	auto &tokenizer = context.tokenizer;
+	tokenizer.skipWhiteSpace();
+
+	// Index on the first element of the current inheritance list
+	size_t inheritanceIndex = 0;
+
+	while (tokenizer.currentCharacter() != ')')
+	{
+		parseAndAddUntypedVariableDeclaration(context, variableDeclarations);
+
+		tokenizer.skipWhiteSpace();
+
+		if (!tokenizer.testAndSkip<char>('-'))
+			continue;
+
+		// If existing, parse and store parent type
+		auto parentType = parsePrimitiveType(context, domain);
+
+		for (size_t i = inheritanceIndex; i < variableDeclarations.size(); i++)
+			variableDeclarations[i]->type = ast::deepCopy(parentType);
+
+		// All types up to now are labeled with their parent types
+		inheritanceIndex = variableDeclarations.size() + 1;
+
+		tokenizer.skipWhiteSpace();
+	}
+
+	return variableDeclarations;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+}
+}
diff --git a/lib/pddlparse/tests/CMakeLists.txt b/lib/pddlparse/tests/CMakeLists.txt
index 9b3c78a..1a89722 100644
--- a/lib/pddlparse/tests/CMakeLists.txt
+++ b/lib/pddlparse/tests/CMakeLists.txt
@@ -5,6 +5,8 @@ file(GLOB core_sources "*.cpp")
 set(includes
 	${PROJECT_SOURCE_DIR}/include
 	${PROJECT_SOURCE_DIR}/../../lib/catch/single_include
+	${PROJECT_SOURCE_DIR}/../../lib/tokenize/include
+	${PROJECT_SOURCE_DIR}/../../lib/variant/include
 )
 
 set(libraries
@@ -18,4 +20,4 @@ target_link_libraries(${target} ${libraries})
 add_custom_target(run-pddlparse-tests
 	COMMAND ${CMAKE_BINARY_DIR}/bin/pddlparse-tests
 	DEPENDS ${target}
-	WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/tests)
+	WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}/../../tests)
diff --git a/lib/pddlparse/tests/TestParser.cpp b/lib/pddlparse/tests/TestParser.cpp
new file mode 100644
index 0000000..978ed58
--- /dev/null
+++ b/lib/pddlparse/tests/TestParser.cpp
@@ -0,0 +1,90 @@
+/*#include <catch.hpp>
+
+#include <pddlparse/AST.h>
+#include <pddlparse/Parse.h>
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+TEST_CASE("[parser] The Blocksworld domain is parsed correctly", "[parser]")
+{
+	const pddl::Context::WarningCallback ignoreWarnings = [](const auto &, const auto &){};
+
+	pddl::Tokenizer tokenizer;
+	tokenizer.read("data/blocksworld-domain.pddl");
+	pddl::Context context(std::move(tokenizer), ignoreWarnings);
+
+	const auto description = pddl::parseDescription(context);
+
+	REQUIRE_NOTHROW(description.domain());
+
+	const auto &domain = description.domain();
+
+	// Name
+	CHECK(domain.name() == "blocks");
+
+	// Requirements
+	REQUIRE(domain.requirements().size() == 2u);
+	CHECK(domain.requirements()[0].type() == Requirement::Type::STRIPS);
+	CHECK(domain.requirements()[1].type() == Requirement::Type::Typing);
+
+	// Types
+	REQUIRE(domain.types().size() == 1u);
+
+	const auto &block = *domain.types()[0];
+
+	CHECK(block.name() == "block");
+	REQUIRE(block.parentTypes().size() == 0u);
+
+	// Predicates
+	REQUIRE(domain.predicates().size() == 5u);
+
+	const auto &on = *domain.predicates()[0];
+
+	CHECK(on.name() == "on");
+	REQUIRE(on.parameters().size() == 2u);
+	CHECK(on.parameters()[0]->name() == "x");
+	const auto &onArgument0Type = on.parameters()[0]->type()->as<expressions::PrimitiveType>();
+	CHECK(&onArgument0Type == &block);
+	CHECK(on.parameters()[1]->name() == "y");
+	const auto &onArgument1Type = on.parameters()[1]->type()->as<expressions::PrimitiveType>();
+	CHECK(&onArgument1Type == &block);
+
+	const auto &handempty = *domain.predicates()[3];
+
+	CHECK(handempty.name() == "handempty");
+	CHECK(handempty.parameters().empty());
+
+	// Actions
+	REQUIRE(domain.actions().size() == 4u);
+
+	const auto &pickUp = *domain.actions()[0];
+
+	CHECK(pickUp.name() == "pick-up");
+	REQUIRE(pickUp.parameters().size() == 1u);
+	CHECK(pickUp.parameters()[0]->name() == "x");
+	CHECK(pickUp.parameters()[0]->type() == &block);
+
+	const auto &pickUpPre = pickUp.precondition()->as<expressions::And>();
+	REQUIRE(pickUpPre.arguments().size() == 3u);
+	const auto &pickUpPre0 = pickUpPre.arguments()[0]->as<expressions::Predicate>();
+	CHECK(pickUpPre0.name() == "clear");
+	REQUIRE(pickUpPre0.arguments().size() == 1u);
+	const auto &pickUpPre00 = pickUpPre0.arguments()[0]->as<expressions::Variable>();
+	CHECK(pickUpPre00.name() == "x");
+	CHECK(pickUpPre00.type() == &block);
+	CHECK(&pickUpPre00 == pickUp.parameters()[0].get());
+	const auto &pickUpPre2 = pickUpPre.arguments()[2]->as<expressions::Predicate>();
+	CHECK(pickUpPre2.name() == "handempty");
+	CHECK(pickUpPre2.arguments().empty());
+
+	const auto &pickUpEff = pickUp.effect()->as<expressions::And>();
+	REQUIRE(pickUpEff.arguments().size() == 4u);
+	const auto &pickUpEff0 = pickUpEff.arguments()[0]->as<expressions::Not>();
+	const auto &pickUpEff00 = pickUpEff0.argument()->as<expressions::Predicate>();
+	CHECK(pickUpEff00.name() == "ontable");
+	REQUIRE(pickUpEff00.arguments().size() == 1u);
+	const auto &pickUpEff000 = pickUpEff00.arguments()[0]->as<expressions::Variable>();
+	CHECK(pickUpEff000.name() == "x");
+	CHECK(pickUpEff000.type() == &block);
+}
+*/
diff --git a/lib/pddlparse/tests/main.cpp b/lib/pddlparse/tests/main.cpp
index b3143fb..e622792 100644
--- a/lib/pddlparse/tests/main.cpp
+++ b/lib/pddlparse/tests/main.cpp
@@ -1,2 +1,22 @@
-#define CATCH_CONFIG_MAIN
+/*#define CATCH_CONFIG_MAIN
 #include <catch.hpp>
+*/
+
+#include <pddlparse/AST.h>
+#include <pddlparse/Parse.h>
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+int main()
+{
+	const pddl::Context::WarningCallback ignoreWarnings = [](const auto &, const auto &){};
+
+	pddl::Tokenizer tokenizer;
+	tokenizer.read("data/blocksworld-domain.pddl");
+	tokenizer.read("data/blocksworld-problem.pddl");
+	pddl::Context context(std::move(tokenizer), ignoreWarnings);
+
+	const auto description = pddl::parseDescription(context);
+
+	std::cout << description.domain->requirements.size() << std::endl;
+}
diff --git a/lib/variant b/lib/variant
new file mode 160000
index 0000000..d2588a8
--- /dev/null
+++ b/lib/variant
@@ -0,0 +1 @@
+Subproject commit d2588a8f1d6b5d480d228e6d8a906ce634bdea9a