Implemented simplification of nested quantified expressions.

include/plasp/pddl/expressions/NAry.h

@@ -178,7 +178,7 @@ inline ExpressionPointer NAry<Derived>::simplified()
 	}
 
 	// TODO: recognize tautologies
-	// TODO: introduce handle boolean values
+	// TODO: introduce/handle boolean values
 
 	return this;
 }

include/plasp/pddl/expressions/Quantified.h

@@ -31,8 +31,12 @@ class Quantified: public ExpressionCRTP<Derived>
 		void setArgument(ExpressionPointer argument);
 		ExpressionPointer argument() const;
 
+		Variables &variables();
+		const Variables &variables() const;
+
 		ExpressionPointer reduced() override;
 		ExpressionPointer negationNormalized() override;
+		ExpressionPointer simplified() override;
 
 		void print(std::ostream &ostream) const override;
 
@@ -98,6 +102,22 @@ ExpressionPointer Quantified<Derived>::argument() const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+template<class Derived>
+Variables &Quantified<Derived>::variables()
+{
+	return m_variables;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+template<class Derived>
+const Variables &Quantified<Derived>::variables() const
+{
+	return m_variables;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 template<class Derived>
 inline ExpressionPointer Quantified<Derived>::reduced()
 {
@@ -118,17 +138,43 @@ inline ExpressionPointer Quantified<Derived>::negationNormalized()
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+template<class Derived>
+inline ExpressionPointer Quantified<Derived>::simplified()
+{
+	m_argument = m_argument->simplified();
+
+	// Associate same-type children, such as (forall (?x) (forall (?y) (...)))
+	if (m_argument->expressionType() != Derived::ExpressionType)
+		return this;
+
+	auto &quantifiedExpression = dynamic_cast<Derived &>(*m_argument);
+
+	BOOST_ASSERT(!quantifiedExpression.arguments().empty());
+
+	// Unify variables
+	m_variables.insert(m_variables.end(), quantifiedExpression.variables().begin(), quantifiedExpression.variables().end());
+
+	// Move child expression up
+	m_argument = quantifiedExpression.argument();
+
+	// TODO: introduce/handle boolean values
+
+	return this;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 template<class Derived>
 inline void Quantified<Derived>::print(std::ostream &ostream) const
 {
-	ostream << "(" << Derived::Identifier << "(";
+	ostream << "(" << Derived::Identifier << " (";
 
 	for (size_t i = 0; i < m_variables.size(); i++)
 	{
 		if (i > 0)
 			ostream << " ";
 
-		ostream << m_variables[i]->name();
+		m_variables[i]->print(ostream);
 	}
 
 	ostream << ") ";

include/plasp/pddl/expressions/Variable.h

@@ -27,6 +27,9 @@ class Variable: public ExpressionCRTP<Variable>
 			Variables &variables);
 
 	public:
+		Variable();
+		Variable(std::string name);
+
 		void setName(std::string name);
 		const std::string &name() const;
 
@@ -42,8 +45,6 @@ class Variable: public ExpressionCRTP<Variable>
 		static void parseDeclaration(Context &context, Variables &parameters);
 
 	private:
-		Variable();
-
 		bool m_isDirty;
 
 		std::string m_name;