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("=")
-		|| tokenizer.testIdentifierAndReturn("at"))
+	if (tokenizer.testIdentifierAndReturn("="))
 	{
 		tokenizer.seek(position);
 		return parseUnsupported(context);
@@ -39,12 +38,20 @@ std::experimental::optional<ast::Fact> parseFact(Context &context, ASTContext &a
 	std::experimental::optional<ast::Fact> fact;
 
 	if ((fact = parseNot<ast::Fact>(context, astContext, variableStack, parseAtomicFormula))
-	    || (fact = parseAtomicFormula(context, astContext, variableStack)))
+		|| (fact = parseAtomicFormula(context, astContext, variableStack)))
 	{
 		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);
+	}
 }