//
// Cforall Version 1.0.0 Copyright (C) 2015 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// TypeEquality.cc -- 
//
// Author           : Rob Schluntz
// Created On       : Tue Jul 07 16:28:29 2015
// Last Modified By : Rob Schluntz
// Last Modified On : Mon Jul 20 14:16:11 2015
// Update Count     : 37
//

#include <list>
#include <iterator>
#include "Validate.h"
#include "SynTree/Visitor.h"
#include "SynTree/Type.h"
#include "SynTree/Statement.h"
#include "SynTree/TypeSubstitution.h"
#include "Indexer.h"
#include "TypeEquality.h"

namespace SymTab {
	class TypeEquality : public Visitor {
  public:
		TypeEquality( Type * other, bool vlaErr ) : result( true ), other( other ), 
			vlaErr( vlaErr ) {}
		bool result;

  private:
		virtual void visit( FunctionType *funcType );
		virtual void visit( VoidType *voidType );
		virtual void visit( BasicType *basicType );
		virtual void visit( PointerType *pointerType );
		virtual void visit( ArrayType *arrayType );
		virtual void visit( StructInstType *structInst );
		virtual void visit( UnionInstType *unionInst );
		virtual void visit( EnumInstType *enumInst );
		virtual void visit( TypeInstType *typeInst );
		virtual void visit( VarArgsType *varArgsType );

		void handleQualifiers( Type * t );

		Type * other;
		bool vlaErr;
	};

	bool typeEquals( Type * t1, Type * t2, bool vlaErr ) {
		TypeEquality teq( t2, vlaErr );
		t1->accept( teq );
		return teq.result;
	}

	void TypeEquality::handleQualifiers( Type * t ) {
		result = result && t->get_qualifiers() == other->get_qualifiers();
	}

	void TypeEquality::visit( VoidType *voidType ) {
		handleQualifiers( voidType );
		if ( ! dynamic_cast< VoidType * >( other ) ) {
			result = false;
		}
	}

	void TypeEquality::visit( BasicType *basicType ) {
		handleQualifiers( basicType );
		if ( BasicType * bt = dynamic_cast< BasicType * >( other ) ) {
			result = result && basicType->get_kind() == bt->get_kind(); 
		} else {
			result = false;
		}
	}

	void TypeEquality::visit( PointerType *pointerType ) {
		handleQualifiers( pointerType );
		if ( PointerType * pt = dynamic_cast< PointerType * >( other ) ) {
			other = pt->get_base();
			pointerType->get_base()->accept( *this );
		} else {
			result = false;
		}
	}

	void TypeEquality::visit( ArrayType *arrayType ) {
		handleQualifiers( arrayType );

		if ( ArrayType * at = dynamic_cast< ArrayType * >( other ) ) {
			// to be equal, array types must both be VLA or both not VLA
			// and must both have a dimension expression or not have a dimension
			result = result	&& arrayType->get_isVarLen() == at->get_isVarLen()
				&& ((arrayType->get_dimension() != 0 && at->get_dimension() != 0)
					|| (arrayType->get_dimension() == 0 && at->get_dimension() == 0));

			if ( vlaErr ) {
				// useful for comparing typedef types - in this case, we 
				// want types to appear distinct if either is a VLA type
				if ( arrayType->get_isVarLen() || at->get_isVarLen() ) {
					result = false;
				}
			}

			if ( ! arrayType->get_isVarLen() && ! at->get_isVarLen() &&
				arrayType->get_dimension() != 0 && at->get_dimension() != 0 ) {
				ConstantExpr * ce1 = dynamic_cast< ConstantExpr * >( arrayType->get_dimension() );
				ConstantExpr * ce2 = dynamic_cast< ConstantExpr * >( at->get_dimension() );
				assert(ce1 && ce2);

				Constant * c1 = ce1->get_constant();
				Constant * c2 = ce2->get_constant();

				result = result && c1->get_value() == c2->get_value();
			}

			other = at->get_base();
			arrayType->get_base()->accept( *this );
		} else {
			result = false;
		}
	}

	void TypeEquality::visit( FunctionType *funcType ) {
		handleQualifiers( funcType );

		if ( FunctionType * ft = dynamic_cast< FunctionType * >( other ) ) {
			// function types must have the same number of return types
			// and parameters to be equivalent
			result = result && funcType->get_returnVals().size() == ft->get_returnVals().size()
				&& funcType->get_parameters().size() == ft->get_parameters().size()
				&& funcType->get_isVarArgs() == ft->get_isVarArgs();

			std::list< DeclarationWithType * >::iterator it1, it2;

			// return types must be equivalent
			it1 = funcType->get_returnVals().begin();
			it2 = ft->get_returnVals().begin();
			for ( ; it1 != funcType->get_returnVals().end(); ++it1, ++it2 ) {
				if ( ! result ) return;
				other = (*it2)->get_type();
				(*it1)->get_type()->accept( *this );
			}

			// parameter types must be equivalent
			it1 = funcType->get_parameters().begin(); 
			it2 = ft->get_parameters().begin();
			for ( ; it1 != funcType->get_parameters().end(); ++it1, ++it2 ) {
				if ( ! result ) return;
				other = (*it2)->get_type();
				(*it1)->get_type()->accept( *this );
			}
		} else {
			result = false;
		}
	}

	// aggregate types only need to have the same name
	void TypeEquality::visit( StructInstType *structInst )  {
		handleQualifiers( structInst );
		if ( StructInstType * st = dynamic_cast< StructInstType * >( other ) ) {
			result = result && structInst->get_name() == st->get_name();
		} else {
			result = false;
		}
	}

	void TypeEquality::visit( UnionInstType *unionInst ) {
		handleQualifiers( unionInst );
		if ( UnionInstType * ut = dynamic_cast< UnionInstType * >( other ) ) {
			result = result && unionInst->get_name() == ut->get_name();
		} else {
			result = false;
		}
	}

	void TypeEquality::visit( EnumInstType *enumInst ) {
		handleQualifiers( enumInst );
		if ( EnumInstType * et = dynamic_cast< EnumInstType * >( other ) ) {
			result = result && enumInst->get_name() == et->get_name();
		} else {
			result = false;
		}
	}

	void TypeEquality::visit( TypeInstType *typeInst ) {
		handleQualifiers( typeInst );
		if ( TypeInstType * tt = dynamic_cast< TypeInstType * >( other ) ) {
			result = result && typeInst->get_name() == tt->get_name();
		} else {
			result = false;
		}
	}

	void TypeEquality::visit( VarArgsType *varArgsType ) {
		handleQualifiers( varArgsType );
		if ( ! dynamic_cast< VarArgsType * >( other ) ) {
			result = false;
		}
	}
} // namespace SymTab