From 9afabacde3d6553635fd1a874d6d3053b22778eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Patrick=20L=C3=BChne?= <patrick-github@luehne.de>
Date: Sun, 4 Sep 2016 18:26:02 +0200
Subject: [PATCH] Switched to intrusive pointers for much easier maintenance.

---
 include/plasp/pddl/Action.h                   |  4 +-
 include/plasp/pddl/Expression.h               | 54 +++++++++----
 include/plasp/pddl/expressions/At.h           |  2 +-
 include/plasp/pddl/expressions/Binary.h       |  6 +-
 include/plasp/pddl/expressions/Constant.h     | 12 +--
 include/plasp/pddl/expressions/NAry.h         |  6 +-
 include/plasp/pddl/expressions/Not.h          |  2 +-
 include/plasp/pddl/expressions/Predicate.h    |  4 +-
 .../plasp/pddl/expressions/PrimitiveType.h    |  6 +-
 include/plasp/pddl/expressions/Reference.h    | 75 -------------------
 include/plasp/pddl/expressions/Type.h         |  2 +-
 include/plasp/pddl/expressions/Variable.h     | 12 +--
 src/plasp/pddl/TranslatorASP.cpp              |  4 +-
 src/plasp/pddl/expressions/Constant.cpp       | 18 ++---
 src/plasp/pddl/expressions/Imply.cpp          |  4 +-
 src/plasp/pddl/expressions/Predicate.cpp      | 12 +--
 .../pddl/expressions/PredicateDeclaration.cpp |  2 +-
 src/plasp/pddl/expressions/PrimitiveType.cpp  | 10 +--
 src/plasp/pddl/expressions/Type.cpp           |  2 +-
 src/plasp/pddl/expressions/Unsupported.cpp    |  2 +-
 src/plasp/pddl/expressions/Variable.cpp       | 39 +++++-----
 tests/TestPDDLNormalization.cpp               | 16 ++--
 22 files changed, 118 insertions(+), 176 deletions(-)
 delete mode 100644 include/plasp/pddl/expressions/Reference.h

diff --git a/include/plasp/pddl/Action.h b/include/plasp/pddl/Action.h
index 56a0fee..35cef85 100644
--- a/include/plasp/pddl/Action.h
+++ b/include/plasp/pddl/Action.h
@@ -38,8 +38,8 @@ class Action
 		std::string m_name;
 
 		expressions::Variables m_parameters;
-		std::unique_ptr<Expression> m_precondition;
-		std::unique_ptr<Expression> m_effect;
+		ExpressionPointer m_precondition;
+		ExpressionPointer m_effect;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/include/plasp/pddl/Expression.h b/include/plasp/pddl/Expression.h
index 4b58dca..7d17863 100644
--- a/include/plasp/pddl/Expression.h
+++ b/include/plasp/pddl/Expression.h
@@ -1,7 +1,7 @@
 #ifndef __PLASP__PDDL__EXPRESSION_H
 #define __PLASP__PDDL__EXPRESSION_H
 
-#include <memory>
+#include <boost/intrusive_ptr.hpp>
 
 #include <plasp/utils/Parser.h>
 
@@ -23,55 +23,58 @@ class ExpressionVisitor;
 class Problem;
 
 class Expression;
-using ExpressionPointer = std::unique_ptr<Expression>;
+using ExpressionPointer = boost::intrusive_ptr<Expression>;
 using Expressions = std::vector<ExpressionPointer>;
 
 namespace expressions
 {
 class And;
-using AndPointer = std::unique_ptr<And>;
+using AndPointer = boost::intrusive_ptr<And>;
 
 class At;
-using AtPointer = std::unique_ptr<At>;
+using AtPointer = boost::intrusive_ptr<At>;
 
 class Constant;
-using ConstantPointer = std::unique_ptr<Constant>;
+using ConstantPointer = boost::intrusive_ptr<Constant>;
 using Constants = std::vector<ConstantPointer>;
 
+class Dummy;
+using DummyPointer = boost::intrusive_ptr<Dummy>;
+
 class Either;
-using EitherPointer = std::unique_ptr<Either>;
+using EitherPointer = boost::intrusive_ptr<Either>;
 
 class Imply;
-using ImplyPointer = std::unique_ptr<Imply>;
+using ImplyPointer = boost::intrusive_ptr<Imply>;
 
 class Not;
-using NotPointer = std::unique_ptr<Not>;
+using NotPointer = boost::intrusive_ptr<Not>;
 
 class Or;
-using OrPointer = std::unique_ptr<Or>;
+using OrPointer = boost::intrusive_ptr<Or>;
 
 class Predicate;
-using PredicatePointer = std::unique_ptr<Predicate>;
+using PredicatePointer = boost::intrusive_ptr<Predicate>;
 using Predicates = std::vector<PredicatePointer>;
 
 class PredicateDeclaration;
-using PredicateDeclarationPointer = std::unique_ptr<PredicateDeclaration>;
+using PredicateDeclarationPointer = boost::intrusive_ptr<PredicateDeclaration>;
 using PredicateDeclarations = std::vector<PredicateDeclarationPointer>;
 
 class PrimitiveType;
-using PrimitiveTypePointer = std::unique_ptr<PrimitiveType>;
+using PrimitiveTypePointer = boost::intrusive_ptr<PrimitiveType>;
 using PrimitiveTypes = std::vector<PrimitiveTypePointer>;
 
 template<class Type>
 class Reference;
 template<class Type>
-using ReferencePointer = std::unique_ptr<Reference<Type>>;
+using ReferencePointer = boost::intrusive_ptr<Reference<Type>>;
 
 class Unsupported;
-using UnsupportedPointer = std::unique_ptr<Unsupported>;
+using UnsupportedPointer = boost::intrusive_ptr<Unsupported>;
 
 class Variable;
-using VariablePointer = std::unique_ptr<Variable>;
+using VariablePointer = boost::intrusive_ptr<Variable>;
 using Variables = std::vector<VariablePointer>;
 }
 
@@ -110,10 +113,31 @@ class Expression
 		//     * a new expression pointer to replace this one if required; this object is then empty
 		//     * nullptr otherwise; the object may or may not have changed
 		virtual ExpressionPointer normalize() = 0;
+
+	private:
+		friend void intrusive_ptr_add_ref(Expression *expression);
+		friend void intrusive_ptr_release(Expression *expression);
+
+		size_t m_referenceCount = 0;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+inline void intrusive_ptr_add_ref(Expression *expression)
+{
+    expression->m_referenceCount++;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+inline void intrusive_ptr_release(Expression *expression)
+{
+    if (--expression->m_referenceCount == 0)
+        delete expression;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
 template<class Derived>
 class ExpressionCRTP: public Expression
 {
diff --git a/include/plasp/pddl/expressions/At.h b/include/plasp/pddl/expressions/At.h
index 7bc8ef4..68457ee 100644
--- a/include/plasp/pddl/expressions/At.h
+++ b/include/plasp/pddl/expressions/At.h
@@ -83,7 +83,7 @@ AtPointer At::parse(Context &context, ExpressionContext &expressionContext,
 		return nullptr;
 	}
 
-	auto expression = std::make_unique<At>(At());
+	auto expression = AtPointer(new At);
 
 	expression->m_timePoint = timePoint;
 
diff --git a/include/plasp/pddl/expressions/Binary.h b/include/plasp/pddl/expressions/Binary.h
index 7ac7e59..543d935 100644
--- a/include/plasp/pddl/expressions/Binary.h
+++ b/include/plasp/pddl/expressions/Binary.h
@@ -24,7 +24,7 @@ class Binary: public ExpressionCRTP<Derived>
 {
 	public:
 		template<typename ExpressionParser>
-		static std::unique_ptr<Derived> parse(Context &context,
+		static boost::intrusive_ptr<Derived> parse(Context &context,
 			ExpressionContext &expressionContext, ExpressionParser parseExpression);
 
 	public:
@@ -45,7 +45,7 @@ class Binary: public ExpressionCRTP<Derived>
 
 template<class Derived>
 template<typename ExpressionParser>
-std::unique_ptr<Derived> Binary<Derived>::parse(Context &context,
+boost::intrusive_ptr<Derived> Binary<Derived>::parse(Context &context,
 	ExpressionContext &expressionContext, ExpressionParser parseExpression)
 {
 	auto &parser = context.parser;
@@ -59,7 +59,7 @@ std::unique_ptr<Derived> Binary<Derived>::parse(Context &context,
 		return nullptr;
 	}
 
-	auto expression = std::make_unique<Derived>();
+	auto expression = boost::intrusive_ptr<Derived>(new Derived);
 
 	// Assume that expression identifier (imply, exists, etc.) is already parsed
 	// Parse arguments of the expression
diff --git a/include/plasp/pddl/expressions/Constant.h b/include/plasp/pddl/expressions/Constant.h
index 4f69f2e..b8d4a49 100644
--- a/include/plasp/pddl/expressions/Constant.h
+++ b/include/plasp/pddl/expressions/Constant.h
@@ -28,12 +28,12 @@ class Constant: public ExpressionCRTP<Constant>
 		static void parseTypedDeclaration(Context &context, Problem &problem);
 		static void parseTypedDeclarations(Context &context, Problem &problem);
 
-		static Constant *parseAndFind(Context &context, const Domain &domain);
-		static Constant *parseAndFind(Context &context, const Problem &problem);
+		static ConstantPointer parseAndFind(Context &context, const Domain &domain);
+		static ConstantPointer parseAndFind(Context &context, const Problem &problem);
 
 	public:
 		const std::string &name() const;
-		const PrimitiveType *type() const;
+		PrimitiveTypePointer type() const;
 
 		ExpressionPointer normalize() override;
 
@@ -41,20 +41,20 @@ class Constant: public ExpressionCRTP<Constant>
 		static ConstantPointer parseDeclaration(Context &context);
 		static void parseTypedDeclaration(Context &context, Domain &domain, Constants &constants);
 
-		static Constant *parseAndFind(const std::string &constantName, const Constants &constants);
+		static ConstantPointer parseAndFind(const std::string &constantName, const Constants &constants);
 
 		Constant();
 
 		void setDirty(bool isDirty = true);
 		bool isDirty() const;
 
-		void setType(const PrimitiveType *parentType);
+		void setType(PrimitiveTypePointer parentType);
 
 		bool m_isDirty;
 
 		std::string m_name;
 
-		const PrimitiveType *m_type;
+		PrimitiveTypePointer m_type;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/include/plasp/pddl/expressions/NAry.h b/include/plasp/pddl/expressions/NAry.h
index c136f38..cc743c9 100644
--- a/include/plasp/pddl/expressions/NAry.h
+++ b/include/plasp/pddl/expressions/NAry.h
@@ -24,7 +24,7 @@ class NAry: public ExpressionCRTP<Derived>
 {
 	public:
 		template<typename ExpressionParser>
-		static std::unique_ptr<Derived> parse(Context &context,
+		static boost::intrusive_ptr<Derived> parse(Context &context,
 			ExpressionContext &expressionContext, ExpressionParser parseExpression);
 
 	public:
@@ -43,7 +43,7 @@ class NAry: public ExpressionCRTP<Derived>
 
 template<class Derived>
 template<typename ExpressionParser>
-std::unique_ptr<Derived> NAry<Derived>::parse(Context &context,
+boost::intrusive_ptr<Derived> NAry<Derived>::parse(Context &context,
 	ExpressionContext &expressionContext, ExpressionParser parseExpression)
 {
 	auto &parser = context.parser;
@@ -57,7 +57,7 @@ std::unique_ptr<Derived> NAry<Derived>::parse(Context &context,
 		return nullptr;
 	}
 
-	auto expression = std::make_unique<Derived>();
+	auto expression = boost::intrusive_ptr<Derived>(new Derived);
 
 	parser.skipWhiteSpace();
 
diff --git a/include/plasp/pddl/expressions/Not.h b/include/plasp/pddl/expressions/Not.h
index a4af388..5e2d362 100644
--- a/include/plasp/pddl/expressions/Not.h
+++ b/include/plasp/pddl/expressions/Not.h
@@ -57,7 +57,7 @@ NotPointer Not::parse(Context &context, ExpressionContext &expressionContext,
 		return nullptr;
 	}
 
-	auto expression = std::make_unique<Not>(Not());
+	auto expression = NotPointer(new Not);
 
 	context.parser.skipWhiteSpace();
 
diff --git a/include/plasp/pddl/expressions/Predicate.h b/include/plasp/pddl/expressions/Predicate.h
index c9f2af0..4b8468e 100644
--- a/include/plasp/pddl/expressions/Predicate.h
+++ b/include/plasp/pddl/expressions/Predicate.h
@@ -26,7 +26,7 @@ class Predicate: public ExpressionCRTP<Predicate>
 
 	public:
 		const std::string &name() const;
-		const std::vector<const Expression *> &arguments() const;
+		const std::vector<ExpressionPointer> &arguments() const;
 
 		bool isDeclared() const;
 
@@ -40,7 +40,7 @@ class Predicate: public ExpressionCRTP<Predicate>
 		bool m_isDeclared;
 
 		std::string m_name;
-		std::vector<const Expression *> m_arguments;
+		std::vector<ExpressionPointer> m_arguments;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/include/plasp/pddl/expressions/PrimitiveType.h b/include/plasp/pddl/expressions/PrimitiveType.h
index 9cd26e9..4f3f476 100644
--- a/include/plasp/pddl/expressions/PrimitiveType.h
+++ b/include/plasp/pddl/expressions/PrimitiveType.h
@@ -26,14 +26,14 @@ class PrimitiveType: public ExpressionCRTP<PrimitiveType>
 		static void parseDeclaration(Context &context, Domain &domain);
 		static void parseTypedDeclaration(Context &context, Domain &domain);
 
-		static PrimitiveType *parseAndFind(Context &context, Domain &domain);
+		static PrimitiveTypePointer parseAndFind(Context &context, Domain &domain);
 
 	public:
 		PrimitiveType();
 		PrimitiveType(std::string name);
 
 		const std::string &name() const;
-		const std::vector<const PrimitiveType *> &parentTypes() const;
+		const std::vector<PrimitiveTypePointer> &parentTypes() const;
 
 		ExpressionPointer normalize() override;
 
@@ -45,7 +45,7 @@ class PrimitiveType: public ExpressionCRTP<PrimitiveType>
 
 		std::string m_name;
 
-		std::vector<const PrimitiveType *> m_parentTypes;
+		std::vector<PrimitiveTypePointer> m_parentTypes;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/include/plasp/pddl/expressions/Reference.h b/include/plasp/pddl/expressions/Reference.h
deleted file mode 100644
index b7ca69a..0000000
--- a/include/plasp/pddl/expressions/Reference.h
+++ /dev/null
@@ -1,75 +0,0 @@
-#ifndef __PLASP__PDDL__EXPRESSIONS__REFERENCE_H
-#define __PLASP__PDDL__EXPRESSIONS__REFERENCE_H
-
-#include <plasp/pddl/Expression.h>
-
-namespace plasp
-{
-namespace pddl
-{
-namespace expressions
-{
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-//
-// Reference
-//
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
-template<class Type>
-class Reference: public ExpressionCRTP<Reference<Type>>
-{
-	public:
-		static const Expression::Type ExpressionType = Expression::Type::Reference;
-
-	public:
-		Reference(Type *value);
-
-		Type *get();
-		const Type *get() const;
-
-		ExpressionPointer normalize();
-
-	protected:
-		Type *m_value = nullptr;
-};
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
-template<class Type>
-Reference<Type>::Reference(Type *value)
-:	m_value{value}
-{
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
-template<class Type>
-Type *Reference<Type>::get()
-{
-	return m_value;
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
-template<class Type>
-const Type *Reference<Type>::get() const
-{
-	return m_value;
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
-template<class Type>
-ExpressionPointer Reference<Type>::normalize()
-{
-	return nullptr;
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
-}
-}
-}
-
-#endif
diff --git a/include/plasp/pddl/expressions/Type.h b/include/plasp/pddl/expressions/Type.h
index fbd43c1..54c09cd 100644
--- a/include/plasp/pddl/expressions/Type.h
+++ b/include/plasp/pddl/expressions/Type.h
@@ -16,7 +16,7 @@ namespace expressions
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-const Expression *parseExistingPrimitiveType(Context &context,
+ExpressionPointer parseExistingPrimitiveType(Context &context,
 	ExpressionContext &expressionContext);
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/include/plasp/pddl/expressions/Variable.h b/include/plasp/pddl/expressions/Variable.h
index ed6d95b..e61e6e1 100644
--- a/include/plasp/pddl/expressions/Variable.h
+++ b/include/plasp/pddl/expressions/Variable.h
@@ -24,20 +24,19 @@ class Variable: public ExpressionCRTP<Variable>
 		static void parseTypedDeclaration(Context &context, ExpressionContext &expressionContext);
 		static void parseTypedDeclarations(Context &context, ExpressionContext &expressionContext);
 
-		static const Variable *parseAndFind(Context &context,
+		static VariablePointer parseAndFind(Context &context,
 			const ExpressionContext &expressionContext);
 
 	public:
 		void setName(std::string name);
 		const std::string &name() const;
 
-		const Expression *type() const;
+		void setType(ExpressionPointer type);
+		ExpressionPointer type() const;
 
 		void setDirty(bool isDirty = true);
 		bool isDirty() const;
 
-		void setType(const Expression *type);
-
 		ExpressionPointer normalize() override;
 
 	private:
@@ -50,10 +49,7 @@ class Variable: public ExpressionCRTP<Variable>
 
 		std::string m_name;
 
-		const Expression *m_type;
-
-		// Stores "either" expression if necessary
-		ExpressionPointer m_eitherExpression;
+		ExpressionPointer m_type;
 };
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
diff --git a/src/plasp/pddl/TranslatorASP.cpp b/src/plasp/pddl/TranslatorASP.cpp
index 183de3c..771eb34 100644
--- a/src/plasp/pddl/TranslatorASP.cpp
+++ b/src/plasp/pddl/TranslatorASP.cpp
@@ -313,7 +313,7 @@ void TranslatorASP::translateConstants(const std::string &heading, const express
 				<< utils::String(constant->name())
 				<< "))." << std::endl;
 
-			const auto *type = constant->type();
+			const auto type = constant->type();
 
 			if (type != nullptr)
 			{
@@ -366,7 +366,7 @@ void TranslatorASP::translateVariablesBody(const expressions::Variables &variabl
 			if (variable.type()->expressionType() != Expression::Type::PrimitiveType)
 				throw utils::TranslatorException("only primitive types supported currently");
 
-			const auto &type = *dynamic_cast<const expressions::PrimitiveType *>(variable.type());
+			const auto &type = dynamic_cast<const expressions::PrimitiveType &>(*variable.type());
 
 			m_outputStream << utils::RuleName("has") << "("
 				<< utils::Variable(variable.name()) << ", "
diff --git a/src/plasp/pddl/expressions/Constant.cpp b/src/plasp/pddl/expressions/Constant.cpp
index e245433..7a9ca85 100644
--- a/src/plasp/pddl/expressions/Constant.cpp
+++ b/src/plasp/pddl/expressions/Constant.cpp
@@ -35,7 +35,7 @@ ConstantPointer Constant::parseDeclaration(Context &context)
 {
 	context.parser.skipWhiteSpace();
 
-	auto constant = std::make_unique<Constant>(Constant());
+	auto constant = ConstantPointer(new Constant);
 
 	constant->m_name = context.parser.parseIdentifier();
 
@@ -75,7 +75,7 @@ void Constant::parseTypedDeclaration(Context &context, Domain &domain, Constants
 		return;
 
 	// If existing, parse and store parent type
-	auto *type = PrimitiveType::parseAndFind(context, domain);
+	auto type = PrimitiveType::parseAndFind(context, domain);
 
 	// Assign parent type to all types that were previously flagged
 	std::for_each(constants.begin(), constants.end(),
@@ -145,7 +145,7 @@ void Constant::parseTypedDeclarations(Context &context, Problem &problem)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Constant *Constant::parseAndFind(Context &context, const Domain &domain)
+ConstantPointer Constant::parseAndFind(Context &context, const Domain &domain)
 {
 	auto &parser = context.parser;
 
@@ -153,7 +153,7 @@ Constant *Constant::parseAndFind(Context &context, const Domain &domain)
 
 	const auto constantName = parser.parseIdentifier();
 
-	auto *constant = parseAndFind(constantName, domain.constants());
+	auto constant = parseAndFind(constantName, domain.constants());
 
 	if (constant != nullptr)
 		return constant;
@@ -163,7 +163,7 @@ Constant *Constant::parseAndFind(Context &context, const Domain &domain)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Constant *Constant::parseAndFind(Context &context, const Problem &problem)
+ConstantPointer Constant::parseAndFind(Context &context, const Problem &problem)
 {
 	auto &parser = context.parser;
 
@@ -171,7 +171,7 @@ Constant *Constant::parseAndFind(Context &context, const Problem &problem)
 
 	const auto constantName = parser.parseIdentifier();
 
-	auto *constant = parseAndFind(constantName, problem.domain().constants());
+	auto constant = parseAndFind(constantName, problem.domain().constants());
 
 	if (constant)
 		return constant;
@@ -186,7 +186,7 @@ Constant *Constant::parseAndFind(Context &context, const Problem &problem)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Constant *Constant::parseAndFind(const std::string &constantName, const Constants &constants)
+ConstantPointer Constant::parseAndFind(const std::string &constantName, const Constants &constants)
 {
 	const auto match = std::find_if(constants.cbegin(), constants.cend(),
 		[&](const auto &constant)
@@ -225,14 +225,14 @@ const std::string &Constant::name() const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Constant::setType(const PrimitiveType *type)
+void Constant::setType(PrimitiveTypePointer type)
 {
 	m_type = type;
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-const PrimitiveType *Constant::type() const
+PrimitiveTypePointer Constant::type() const
 {
 	return m_type;
 }
diff --git a/src/plasp/pddl/expressions/Imply.cpp b/src/plasp/pddl/expressions/Imply.cpp
index 1776116..965e371 100644
--- a/src/plasp/pddl/expressions/Imply.cpp
+++ b/src/plasp/pddl/expressions/Imply.cpp
@@ -26,10 +26,10 @@ ExpressionPointer Imply::normalize()
 	BOOST_ASSERT(m_argumentStorage[0]);
 	BOOST_ASSERT(m_argumentStorage[1]);
 
-	auto notArgument0 = std::make_unique<Not>();
+	auto notArgument0 = NotPointer(new Not);
 	notArgument0->setArgument(std::move(m_argumentStorage[0]));
 
-	auto orExpression = std::make_unique<Or>();
+	auto orExpression = OrPointer(new Or);
 	orExpression->addArgument(std::move(notArgument0));
 	orExpression->addArgument(std::move(m_argumentStorage[1]));
 
diff --git a/src/plasp/pddl/expressions/Predicate.cpp b/src/plasp/pddl/expressions/Predicate.cpp
index 59bf051..7b0b80f 100644
--- a/src/plasp/pddl/expressions/Predicate.cpp
+++ b/src/plasp/pddl/expressions/Predicate.cpp
@@ -54,7 +54,7 @@ PredicatePointer Predicate::parse(Context &context, ExpressionContext &expressio
 		return nullptr;
 	}
 
-	auto predicate = std::make_unique<Predicate>(Predicate());
+	auto predicate = PredicatePointer(new Predicate);
 
 	predicate->m_name = predicateName;
 
@@ -66,13 +66,13 @@ PredicatePointer Predicate::parse(Context &context, ExpressionContext &expressio
 		// Parse variables
 		if (context.parser.currentCharacter() == '?')
 		{
-			const auto *variable = Variable::parseAndFind(context, expressionContext);
+			const auto variable = Variable::parseAndFind(context, expressionContext);
 			predicate->m_arguments.emplace_back(variable);
 		}
 		// Parse constants
 		else
 		{
-			const auto *constant = (expressionContext.problem == nullptr)
+			const auto constant = (expressionContext.problem == nullptr)
 				? Constant::parseAndFind(context, expressionContext.domain)
 				: Constant::parseAndFind(context, *expressionContext.problem);
 			predicate->m_arguments.emplace_back(constant);
@@ -117,7 +117,7 @@ PredicatePointer Predicate::parse(Context &context, const Problem &problem)
 		return nullptr;
 	}
 
-	auto predicate = std::make_unique<Predicate>(Predicate());
+	auto predicate = PredicatePointer(new Predicate);
 
 	predicate->m_name = predicateName;
 
@@ -129,7 +129,7 @@ PredicatePointer Predicate::parse(Context &context, const Problem &problem)
 			throw utils::ParserException(parser.coordinate(), "variables not allowed in this context");
 
 		// Parse objects and constants
-		const auto *constant = Constant::parseAndFind(context, problem);
+		const auto constant = Constant::parseAndFind(context, problem);
 		predicate->m_arguments.emplace_back(constant);
 	}
 
@@ -163,7 +163,7 @@ const std::string &Predicate::name() const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-const std::vector<const Expression *> &Predicate::arguments() const
+const std::vector<ExpressionPointer> &Predicate::arguments() const
 {
 	return m_arguments;
 }
diff --git a/src/plasp/pddl/expressions/PredicateDeclaration.cpp b/src/plasp/pddl/expressions/PredicateDeclaration.cpp
index a3d8f84..6823fe4 100644
--- a/src/plasp/pddl/expressions/PredicateDeclaration.cpp
+++ b/src/plasp/pddl/expressions/PredicateDeclaration.cpp
@@ -30,7 +30,7 @@ void PredicateDeclaration::parse(Context &context, Domain &domain)
 {
 	context.parser.expect<std::string>("(");
 
-	auto predicate = std::make_unique<PredicateDeclaration>(PredicateDeclaration());
+	auto predicate = PredicateDeclarationPointer(new PredicateDeclaration);
 
 	predicate->m_name = context.parser.parseIdentifier();
 
diff --git a/src/plasp/pddl/expressions/PrimitiveType.cpp b/src/plasp/pddl/expressions/PrimitiveType.cpp
index 9f23558..9bc88fe 100644
--- a/src/plasp/pddl/expressions/PrimitiveType.cpp
+++ b/src/plasp/pddl/expressions/PrimitiveType.cpp
@@ -61,7 +61,7 @@ void PrimitiveType::parseDeclaration(Context &context, Domain &domain)
 		return;
 	}
 
-	types.emplace_back(std::make_unique<PrimitiveType>(typeName));
+	types.emplace_back(PrimitiveTypePointer(new PrimitiveType(typeName)));
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -82,7 +82,7 @@ void PrimitiveType::parseTypedDeclaration(Context &context, Domain &domain)
 	domain.checkRequirement(Requirement::Type::Typing);
 
 	// If existing, parse and store parent type
-	auto *parentType = parseAndFind(context, domain);
+	auto parentType = parseAndFind(context, domain);
 
 	parentType->setDirty(false);
 
@@ -100,7 +100,7 @@ void PrimitiveType::parseTypedDeclaration(Context &context, Domain &domain)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-PrimitiveType *PrimitiveType::parseAndFind(Context &context, Domain &domain)
+PrimitiveTypePointer PrimitiveType::parseAndFind(Context &context, Domain &domain)
 {
 	auto &parser = context.parser;
 
@@ -125,7 +125,7 @@ PrimitiveType *PrimitiveType::parseAndFind(Context &context, Domain &domain)
 		if (typeName == "object" || typeName == "objects")
 		{
 			context.logger.logWarning(parser.coordinate(), "primitive type “" + typeName + "” should be declared");
-			types.emplace_back(std::make_unique<expressions::PrimitiveType>(typeName));
+			types.emplace_back(PrimitiveTypePointer(new PrimitiveType(typeName)));
 		}
 		else
 			throw utils::ParserException(parser.coordinate(), "type “" + typeName + "” used but never declared");
@@ -162,7 +162,7 @@ const std::string &PrimitiveType::name() const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-const std::vector<const PrimitiveType *> &PrimitiveType::parentTypes() const
+const std::vector<PrimitiveTypePointer> &PrimitiveType::parentTypes() const
 {
 	return m_parentTypes;
 }
diff --git a/src/plasp/pddl/expressions/Type.cpp b/src/plasp/pddl/expressions/Type.cpp
index 49b81f0..e4cab3f 100644
--- a/src/plasp/pddl/expressions/Type.cpp
+++ b/src/plasp/pddl/expressions/Type.cpp
@@ -17,7 +17,7 @@ namespace expressions
 //
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-const Expression *parseExistingPrimitiveType(Context &context, ExpressionContext &expressionContext)
+ExpressionPointer parseExistingPrimitiveType(Context &context, ExpressionContext &expressionContext)
 {
 	return PrimitiveType::parseAndFind(context, expressionContext.domain);
 }
diff --git a/src/plasp/pddl/expressions/Unsupported.cpp b/src/plasp/pddl/expressions/Unsupported.cpp
index fdff330..3b38400 100644
--- a/src/plasp/pddl/expressions/Unsupported.cpp
+++ b/src/plasp/pddl/expressions/Unsupported.cpp
@@ -19,7 +19,7 @@ UnsupportedPointer Unsupported::parse(Context &context)
 {
 	auto &parser = context.parser;
 
-	auto expression = std::make_unique<Unsupported>(Unsupported());
+	auto expression = UnsupportedPointer(new Unsupported);
 
 	parser.expect<std::string>("(");
 
diff --git a/src/plasp/pddl/expressions/Variable.cpp b/src/plasp/pddl/expressions/Variable.cpp
index 9e137e8..81255a7 100644
--- a/src/plasp/pddl/expressions/Variable.cpp
+++ b/src/plasp/pddl/expressions/Variable.cpp
@@ -41,7 +41,7 @@ void Variable::parseDeclaration(Context &context, Variables &parameters)
 
 	parser.expect<std::string>("?");
 
-	auto variable = std::make_unique<Variable>(Variable());
+	auto variable = VariablePointer(new Variable);
 
 	variable->m_name = parser.parseIdentifier();
 
@@ -58,7 +58,7 @@ void Variable::parseDeclaration(Context &context, Variables &parameters)
 	// Flag variable for potentially upcoming type declaration
 	variable->setDirty();
 
-	parameters.emplace_back(std::move(variable));
+	parameters.emplace_back(variable);
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -80,7 +80,7 @@ void Variable::parseTypedDeclaration(Context &context, ExpressionContext &expres
 		return;
 
 	const auto setType =
-		[&](const auto *type)
+		[&](ExpressionPointer type)
 		{
 			// Set the argument type for all previously flagged arguments
 			std::for_each(variables.begin(), variables.end(),
@@ -96,17 +96,14 @@ void Variable::parseTypedDeclaration(Context &context, ExpressionContext &expres
 
 	parser.skipWhiteSpace();
 
-	// Parse argument of "either" type (always begins with opening parenthesis)
-	if ((variable->m_eitherExpression = Either::parse(context, expressionContext, parseExistingPrimitiveType)))
-	{
-		setType(variable->m_eitherExpression.get());
-		return;
-	}
+	// Parse argument if it has "either" type (always begins with opening parenthesis)
+	variable->m_type = Either::parse(context, expressionContext, parseExistingPrimitiveType);
 
-	// Parse primitive type
-	const auto *type = PrimitiveType::parseAndFind(context, expressionContext.domain);
+	// Else, try parsing it as a primitive type
+	if (!variable->m_type)
+		variable->m_type = PrimitiveType::parseAndFind(context, expressionContext.domain);
 
-	setType(type);
+	setType(variable->m_type);
 }
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
@@ -138,7 +135,7 @@ void Variable::parseTypedDeclarations(Context &context, ExpressionContext &expre
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-const Variable *Variable::parseAndFind(Context &context, const ExpressionContext &expressionContext)
+VariablePointer Variable::parseAndFind(Context &context, const ExpressionContext &expressionContext)
 {
 	auto &parser = context.parser;
 
@@ -178,7 +175,14 @@ const std::string &Variable::name() const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-const Expression *Variable::type() const
+void Variable::setType(ExpressionPointer type)
+{
+	m_type = type;
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////
+
+ExpressionPointer Variable::type() const
 {
 	return m_type;
 }
@@ -199,13 +203,6 @@ bool Variable::isDirty() const
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-void Variable::setType(const Expression *type)
-{
-	m_type = type;
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
 ExpressionPointer Variable::normalize()
 {
 	return nullptr;
diff --git a/tests/TestPDDLNormalization.cpp b/tests/TestPDDLNormalization.cpp
index fb61426..add8b97 100644
--- a/tests/TestPDDLNormalization.cpp
+++ b/tests/TestPDDLNormalization.cpp
@@ -11,14 +11,14 @@ using namespace plasp::pddl;
 
 TEST(PDDLNormalizationTests, Implication)
 {
-	auto i = std::make_unique<expressions::Imply>();
-	auto d1 = std::make_unique<expressions::Dummy>();
+	auto i = expressions::ImplyPointer(new expressions::Imply);
+	auto d1 = expressions::DummyPointer(new expressions::Dummy);
 	const auto d1p = d1.get();
-	auto d2 = std::make_unique<expressions::Dummy>();
+	auto d2 = expressions::DummyPointer(new expressions::Dummy);
 	const auto d2p = d2.get();
 
-	i->setArgument<0>(std::move(d1));
-	i->setArgument<1>(std::move(d2));
+	i->setArgument<0>(d1);
+	i->setArgument<1>(d2);
 
 	auto normalized = i->normalize();
 
@@ -40,9 +40,9 @@ TEST(PDDLNormalizationTests, Implication)
 
 TEST(PDDLNormalizationTests, DoubleNegation)
 {
-	auto n1 = std::make_unique<expressions::Not>();
-	auto n2 = std::make_unique<expressions::Not>();
-	auto d = std::make_unique<expressions::Dummy>();
+	auto n1 = expressions::NotPointer(new expressions::Not);
+	auto n2 = expressions::NotPointer(new expressions::Not);
+	auto d = expressions::DummyPointer(new expressions::Dummy);
 	const auto dp = d.get();
 
 	n2->setArgument(std::move(d));