Allowing “at” as a predicate name even though it is an expression identifier.

lib/pddlparse/src/pddlparse/detail/parsing/Fact.cpp

@@ -26,8 +26,7 @@ std::experimental::optional<ast::Fact> parseFact(Context &context, ASTContext &a
 	tokenizer.expect<std::string>("(");
 	tokenizer.skipWhiteSpace();
 
-	if (tokenizer.testIdentifierAndReturn("=")
+	if (tokenizer.testIdentifierAndReturn("="))
-		|| tokenizer.testIdentifierAndReturn("at"))
 	{
 		tokenizer.seek(position);
 		return parseUnsupported(context);
@@ -44,7 +43,15 @@ std::experimental::optional<ast::Fact> parseFact(Context &context, ASTContext &a
 		return std::move(fact.value());
 	}
 
-	return parseAtomicFormula(context, astContext, variableStack);
+	// Test for “at” expressions only now to allow “at” as a predicate name
+	// TODO: allow this in compatibility mode only?
+	if (tokenizer.testIdentifierAndReturn("at"))
+	{
+		tokenizer.seek(position);
+		return parseUnsupported(context);
+	}
+
+	return std::experimental::nullopt;
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////

lib/pddlparse/tests/TestIssues.cpp

@@ -60,4 +60,30 @@ TEST_CASE("[PDDL parser issues] Check past issues", "[PDDL parser issues]")
 		context.tokenizer.read(domainFile);
 		CHECK_THROWS(pddl::parseDescription(context));
 	}
+
+	// Check that “at” is allowed as a predicate name and not exclusively for “at” expressions
+	SECTION("“at” as predicate name")
+	{
+		const auto domainFile = fs::path("data") / "issues" / "issue-10.pddl";
+		context.tokenizer.read(domainFile);
+
+		const auto description = pddl::parseDescription(context);
+
+		REQUIRE(description.problem);
+
+		const auto &problem = description.problem.value();
+		const auto &facts = problem->initialState.facts;
+
+		const auto invalidFact = std::find_if(facts.cbegin(), facts.cend(),
+			[](const auto &fact)
+			{
+				return
+					fact.template is<pddl::ast::AtPointer<pddl::ast::Literal>>()
+					|| (fact.template is<pddl::ast::AtomicFormula>() && fact.template get<pddl::ast::AtomicFormula>().template is<pddl::ast::UnsupportedPointer>());
+			});
+
+		const auto containsInvalidFact = (invalidFact != facts.cend());
+
+		CHECK(!containsInvalidFact);
+	}
 }

tests/data/issues/issue-10.pddl

@@ -0,0 +1,160 @@
+(define (domain logistics-strips)
+  (:requirements :strips) 
+  (:predicates 	(OBJ ?obj)
+	       	(TRUCK ?truck)
+               	(LOCATION ?loc)
+		(AIRPLANE ?airplane)
+                (CITY ?city)
+                (AIRPORT ?airport)
+		(at ?obj ?loc)
+		(in ?obj1 ?obj2)
+		(in-city ?obj ?city))
+ 
+  ; (:types )		; default object
+
+(:action LOAD-TRUCK
+  :parameters
+   (?obj
+    ?truck
+    ?loc)
+  :precondition
+   (and (OBJ ?obj) (TRUCK ?truck) (LOCATION ?loc)
+   (at ?truck ?loc) (at ?obj ?loc))
+  :effect
+   (and (not (at ?obj ?loc)) (in ?obj ?truck)))
+
+(:action LOAD-AIRPLANE
+  :parameters
+   (?obj
+    ?airplane
+    ?loc)
+  :precondition
+   (and (OBJ ?obj) (AIRPLANE ?airplane) (LOCATION ?loc)
+   (at ?obj ?loc) (at ?airplane ?loc))
+  :effect
+   (and (not (at ?obj ?loc)) (in ?obj ?airplane)))
+
+(:action UNLOAD-TRUCK
+  :parameters
+   (?obj
+    ?truck
+    ?loc)
+  :precondition
+   (and (OBJ ?obj) (TRUCK ?truck) (LOCATION ?loc)
+        (at ?truck ?loc) (in ?obj ?truck))
+  :effect
+   (and (not (in ?obj ?truck)) (at ?obj ?loc)))
+
+(:action UNLOAD-AIRPLANE
+  :parameters
+   (?obj
+    ?airplane
+    ?loc)
+  :precondition
+   (and (OBJ ?obj) (AIRPLANE ?airplane) (LOCATION ?loc)
+        (in ?obj ?airplane) (at ?airplane ?loc))
+  :effect
+   (and (not (in ?obj ?airplane)) (at ?obj ?loc)))
+
+(:action DRIVE-TRUCK
+  :parameters
+   (?truck
+    ?loc-from
+    ?loc-to
+    ?city)
+  :precondition
+   (and (TRUCK ?truck) (LOCATION ?loc-from) (LOCATION ?loc-to) (CITY ?city)
+   (at ?truck ?loc-from)
+   (in-city ?loc-from ?city)
+   (in-city ?loc-to ?city))
+  :effect
+   (and (not (at ?truck ?loc-from)) (at ?truck ?loc-to)))
+
+(:action FLY-AIRPLANE
+  :parameters
+   (?airplane
+    ?loc-from
+    ?loc-to)
+  :precondition
+   (and (AIRPLANE ?airplane) (AIRPORT ?loc-from) (AIRPORT ?loc-to)
+	(at ?airplane ?loc-from))
+  :effect
+   (and (not (at ?airplane ?loc-from)) (at ?airplane ?loc-to)))
+)
+(define (problem strips-log-x-1)
+   (:domain logistics-strips)
+   (:objects package6 package5 package4 package3 package2 package1
+             city6 city5 city4 city3 city2 city1 truck6 truck5 truck4
+             truck3 truck2 truck1 plane2 plane1 city6-1 city5-1 city4-1
+             city3-1 city2-1 city1-1 city6-2 city5-2 city4-2 city3-2
+             city2-2 city1-2)
+   (:init (obj package6)
+          (obj package5)
+          (obj package4)
+          (obj package3)
+          (obj package2)
+          (obj package1)
+          (city city6)
+          (city city5)
+          (city city4)
+          (city city3)
+          (city city2)
+          (city city1)
+          (truck truck6)
+          (truck truck5)
+          (truck truck4)
+          (truck truck3)
+          (truck truck2)
+          (truck truck1)
+          (airplane plane2)
+          (airplane plane1)
+          (location city6-1)
+          (location city5-1)
+          (location city4-1)
+          (location city3-1)
+          (location city2-1)
+          (location city1-1)
+          (airport city6-2)
+          (location city6-2)
+          (airport city5-2)
+          (location city5-2)
+          (airport city4-2)
+          (location city4-2)
+          (airport city3-2)
+          (location city3-2)
+          (airport city2-2)
+          (location city2-2)
+          (airport city1-2)
+          (location city1-2)
+          (in-city city6-2 city6)
+          (in-city city6-1 city6)
+          (in-city city5-2 city5)
+          (in-city city5-1 city5)
+          (in-city city4-2 city4)
+          (in-city city4-1 city4)
+          (in-city city3-2 city3)
+          (in-city city3-1 city3)
+          (in-city city2-2 city2)
+          (in-city city2-1 city2)
+          (in-city city1-2 city1)
+          (in-city city1-1 city1)
+          (at plane2 city4-2)
+          (at plane1 city4-2)
+          (at truck6 city6-1)
+          (at truck5 city5-1)
+          (at truck4 city4-1)
+          (at truck3 city3-1)
+          (at truck2 city2-1)
+          (at truck1 city1-1)
+          (at package6 city3-1)
+          (at package5 city4-2)
+          (at package4 city1-1)
+          (at package3 city1-1)
+          (at package2 city1-2)
+          (at package1 city2-1))
+   (:goal (and (at package6 city1-2)
+               (at package5 city6-2)
+               (at package4 city3-2)
+               (at package3 city6-1)
+               (at package2 city6-2)
+               (at package1 city2-1))))