//
// 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.
//
// Lvalue.cc -- 
//
// Author           : Richard C. Bilson
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Peter A. Buhr
// Last Modified On : Tue May 19 07:41:33 2015
// Update Count     : 1
//

#include <cassert>

#include "Lvalue.h"

#include "SynTree/Declaration.h"
#include "SynTree/Type.h"
#include "SynTree/Expression.h"
#include "SynTree/Statement.h"
#include "SynTree/Visitor.h"
#include "SynTree/Mutator.h"
#include "SymTab/Indexer.h"
#include "ResolvExpr/Resolver.h"
#include "ResolvExpr/typeops.h"

#include "UniqueName.h"
#include "utility.h"

namespace GenPoly {
	namespace {
		const std::list<Label> noLabels;

		class Pass1 : public Mutator {
		  public:
			Pass1();
  
			virtual Expression *mutate( ApplicationExpr *appExpr );
			virtual Statement *mutate( ReturnStmt *appExpr );
			virtual DeclarationWithType *mutate( FunctionDecl *funDecl );
		  private:
			DeclarationWithType* retval;
		};

		class Pass2 : public Visitor {
		  public:
			virtual void visit( FunctionType *funType );
		  private:
		};
	} // namespace

	void convertLvalue( std::list< Declaration* >& translationUnit ) {
		Pass1 p1;
		Pass2 p2;
		mutateAll( translationUnit, p1 );
		acceptAll( translationUnit, p2 );
	}

	namespace {
		bool isLvalueRet( FunctionType *function ) {
			if ( ! function->get_returnVals().empty() ) {
				return function->get_returnVals().front()->get_type()->get_isLvalue();
			} else {
				return false;
			} // if
		}

		bool isIntrinsicApp( ApplicationExpr *appExpr ) {
			if ( VariableExpr *varExpr = dynamic_cast< VariableExpr* >( appExpr->get_function() ) ) {
				return varExpr->get_var()->get_linkage() == LinkageSpec::Intrinsic;
			} else {
				return false;
			} // if
		}

		Pass1::Pass1() {
		}

		DeclarationWithType * Pass1::mutate( FunctionDecl *funcDecl ) {
			if ( funcDecl->get_statements() ) {
				DeclarationWithType* oldRetval = retval;
				retval = 0;
				if ( ! LinkageSpec::isBuiltin( funcDecl->get_linkage() ) && isLvalueRet( funcDecl->get_functionType() ) ) {
					retval = funcDecl->get_functionType()->get_returnVals().front();
				}
				// fix expressions and return statements in this function
				funcDecl->set_statements( funcDecl->get_statements()->acceptMutator( *this ) );
				retval = oldRetval;
			} // if
			return funcDecl;
		}

		Expression * Pass1::mutate( ApplicationExpr *appExpr ) {
			appExpr->get_function()->acceptMutator( *this );
			mutateAll( appExpr->get_args(), *this );
  
			assert( ! appExpr->get_function()->get_results().empty() );

			PointerType *pointer = dynamic_cast< PointerType* >( appExpr->get_function()->get_results().front() );
			assert( pointer );
			FunctionType *function = dynamic_cast< FunctionType* >( pointer->get_base() );
			assert( function );

			std::string typeName;
			if ( isLvalueRet( function ) && ! isIntrinsicApp( appExpr ) ) {
				UntypedExpr *deref = new UntypedExpr( new NameExpr( "*?" ) );
				deref->get_results().push_back( appExpr->get_results().front() );
				appExpr->get_results().front() = new PointerType( Type::Qualifiers(), deref->get_results().front()->clone() );
				deref->get_args().push_back( appExpr );
				return deref;
			} else {
				return appExpr;
			} // if
		}

		Statement * Pass1::mutate(ReturnStmt *retStmt) {
			if ( retval && retStmt->get_expr() ) {
				assert( ! retStmt->get_expr()->get_results().empty() );
				while ( CastExpr *castExpr = dynamic_cast< CastExpr* >( retStmt->get_expr() ) ) {
					retStmt->set_expr( castExpr->get_arg() );
					retStmt->get_expr()->set_env( castExpr->get_env() );
					castExpr->set_env( 0 );
					castExpr->set_arg( 0 );
					delete castExpr;
				} // while
				if ( retStmt->get_expr()->get_results().front()->get_isLvalue() ) {
					retStmt->set_expr( new AddressExpr( retStmt->get_expr()->acceptMutator( *this ) ) );
				} else {
					throw SemanticError( "Attempt to return non-lvalue from an lvalue-qualified function" );
				} // if
			} // if
			return retStmt;
		}

		void Pass2::visit( FunctionType *funType ) {
			std::string typeName;
			if ( isLvalueRet( funType ) ) {
				DeclarationWithType *retParm = funType->get_returnVals().front();

				// make a new parameter that is a pointer to the type of the old return value
				retParm->set_type( new PointerType( Type::Qualifiers(), retParm->get_type() ) );
			} // if
  
			Visitor::visit( funType );
		}
	} // namespace
} // namespace GenPoly

// Local Variables: //
// tab-width: 4 //
// mode: c++ //
// compile-command: "make install" //
// End: //