Remove Constant class

Constants are not a construct present in Clingo’s AST and were
unintentionally made part of anthem’s AST. This removes the unused
classes for clarity.

include/anthem/AST.h

@@ -103,23 +103,6 @@ struct Comparison
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-struct Constant
-{
-	explicit Constant(std::string &&name)
-	:	name{std::move(name)}
-	{
-	}
-
-	Constant(const Constant &other) = delete;
-	Constant &operator=(const Constant &other) = delete;
-	Constant(Constant &&other) = default;
-	Constant &operator=(Constant &&other) = default;
-
-	std::string name;
-};
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
 struct Function
 {
 	explicit Function(std::string &&name)

include/anthem/ASTCopy.h

@@ -22,7 +22,6 @@ namespace ast
 BinaryOperation prepareCopy(const BinaryOperation &other);
 Boolean prepareCopy(const Boolean &other);
 Comparison prepareCopy(const Comparison &other);
-Constant prepareCopy(const Constant &other);
 Function prepareCopy(const Function &other);
 In prepareCopy(const In &other);
 Integer prepareCopy(const Integer &other);

include/anthem/ASTForward.h

@@ -24,7 +24,6 @@ struct BinaryOperation;
 struct Biconditional;
 struct Boolean;
 struct Comparison;
-struct Constant;
 struct Exists;
 struct ForAll;
 struct Function;
@@ -63,7 +62,6 @@ using Formula = Clingo::Variant<
 using Term = Clingo::Variant<
 	BinaryOperation,
 	Boolean,
-	Constant,
 	Function,
 	Integer,
 	Interval,

include/anthem/ASTVisitors.h

@@ -123,12 +123,6 @@ struct RecursiveTermVisitor
 		return T::accept(boolean, term, std::forward<Arguments>(arguments)...);
 	}
 
-	template <class... Arguments>
-	ReturnType visit(Constant &constant, Term &term, Arguments &&... arguments)
-	{
-		return T::accept(constant, term, std::forward<Arguments>(arguments)...);
-	}
-
 	template <class... Arguments>
 	ReturnType visit(Function &function, Term &term, Arguments &&... arguments)
 	{

include/anthem/Equality.h

@@ -298,18 +298,6 @@ struct TermEqualityVisitor
 			: Tristate::False;
 	}
 
-	Tristate visit(const Constant &constant, const Term &otherTerm)
-	{
-		if (!otherTerm.is<Constant>())
-			return Tristate::Unknown;
-
-		const auto &otherConstant = otherTerm.get<Constant>();
-
-		return (constant.name == otherConstant.name)
-			? Tristate::True
-			: Tristate::False;
-	}
-
 	Tristate visit(const Function &function, const Term &otherTerm)
 	{
 		if (!otherTerm.is<Function>())

include/anthem/SimplificationVisitors.h

@@ -137,12 +137,6 @@ struct TermSimplificationVisitor
 		return T::accept(term, std::forward<Arguments>(arguments)...);
 	}
 
-	template <class... Arguments>
-	SimplificationResult visit(Constant &, Term &term, Arguments &&... arguments)
-	{
-		return T::accept(term, std::forward<Arguments>(arguments)...);
-	}
-
 	template <class... Arguments>
 	SimplificationResult visit(Function &function, Term &term, Arguments &&... arguments)
 	{

include/anthem/output/AST.h

@@ -46,7 +46,6 @@ output::ColorStream &print(output::ColorStream &stream, const BinaryOperation &b
 output::ColorStream &print(output::ColorStream &stream, const Boolean &boolean, PrintContext &printContext, bool omitParentheses = false);
 output::ColorStream &print(output::ColorStream &stream, const Comparison &comparison, PrintContext &printContext, bool omitParentheses = false);
 output::ColorStream &print(output::ColorStream &stream, Comparison::Operator operator_, PrintContext &printContext, bool omitParentheses = false);
-output::ColorStream &print(output::ColorStream &stream, const Constant &constant, PrintContext &printContext, bool omitParentheses = false);
 output::ColorStream &print(output::ColorStream &stream, const Function &function, PrintContext &printContext, bool omitParentheses = false);
 output::ColorStream &print(output::ColorStream &stream, const In &in, PrintContext &printContext, bool omitParentheses = false);
 output::ColorStream &print(output::ColorStream &stream, const Integer &integer, PrintContext &printContext, bool omitParentheses = false);
@@ -167,13 +166,6 @@ inline output::ColorStream &print(output::ColorStream &stream, const Comparison
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-inline output::ColorStream &print(output::ColorStream &stream, const Constant &constant, PrintContext &, bool)
-{
-	return (stream << constant.name);
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
 inline output::ColorStream &print(output::ColorStream &stream, const Function &function, PrintContext &printContext, bool)
 {
 	stream << function.name;

src/anthem/ASTCopy.cpp

@@ -103,13 +103,6 @@ Comparison prepareCopy(const Comparison &other)
 
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
-Constant prepareCopy(const Constant &other)
-{
-	return Constant(std::string(other.name));
-}
-
-////////////////////////////////////////////////////////////////////////////////////////////////////
-
 Function prepareCopy(const Function &other)
 {
 	return Function(std::string(other.name), prepareCopy(other.arguments));
@@ -293,11 +286,6 @@ struct FixDanglingVariablesInTermVisitor
 	{
 	}
 
-	template <class... Arguments>
-	void visit(Constant &, Arguments &&...)
-	{
-	}
-
 	template <class... Arguments>
 	void visit(Function &function, Arguments &&... arguments)
 	{

src/anthem/ASTUtils.cpp

@@ -150,10 +150,6 @@ struct CollectFreeVariablesVisitor
 		binaryOperation.right.accept(*this, variableStack, freeVariables);
 	}
 
-	void visit(Constant &, VariableStack &, std::vector<VariableDeclaration *> &)
-	{
-	}
-
 	void visit(Function &function, VariableStack &variableStack, std::vector<VariableDeclaration *> &freeVariables)
 	{
 		for (auto &argument : function.arguments)