//
// 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.
//
// RemoveInit.cc --
//
// Author           : Rob Schluntz
// Created On       : Mon May 18 07:44:20 2015
// Last Modified By : Rob Schluntz
// Last Modified On : Tue Feb 09 15:12:29 2016
// Update Count     : 166
//

#include <stack>
#include <list>
#include "RemoveInit.h"
#include "SynTree/Declaration.h"
#include "SynTree/Type.h"
#include "SynTree/Expression.h"
#include "SynTree/Statement.h"
#include "SynTree/Initializer.h"
#include "SynTree/Mutator.h"
#include "GenPoly/PolyMutator.h"

namespace InitTweak {
	namespace {
		const std::list<Label> noLabels;
	}

	class RemoveInit : public GenPoly::PolyMutator {
	  public:
		/// removes and replaces initialization for polymorphic value objects
		/// with assignment (TODO: constructor) statements.
		/// also consistently allocates a temporary variable for the return value
		/// of a function so that anything which the resolver decides can be assigned
		/// into the return type of a function can be returned.
		static void removeInitializers( std::list< Declaration * > &translationUnit );

		RemoveInit();
		virtual ObjectDecl * mutate( ObjectDecl *objDecl );
		virtual DeclarationWithType * mutate( FunctionDecl *functionDecl );

		virtual Statement * mutate( ReturnStmt * returnStmt );

	  protected:
		std::list<DeclarationWithType*> returnVals;
		UniqueName tempNamer;
		std::string funcName;
	};

	class CtorDtor : public GenPoly::PolyMutator {
	  public:
		/// create constructor and destructor statements for object declarations.
		/// Destructors are inserted directly into the code, whereas constructors
		/// will be added in after the resolver has run so that the initializer expression
		/// is only removed if a constructor is found
		static void generateCtorDtor( std::list< Declaration * > &translationUnit );

		CtorDtor() : inFunction( false ) {}

		virtual ObjectDecl * mutate( ObjectDecl * );
		virtual DeclarationWithType * mutate( FunctionDecl *functionDecl );
		virtual Declaration* mutate( StructDecl *aggregateDecl );
		virtual Declaration* mutate( UnionDecl *aggregateDecl );
		virtual Declaration* mutate( EnumDecl *aggregateDecl );
		virtual Declaration* mutate( ContextDecl *aggregateDecl );
		virtual TypeDecl* mutate( TypeDecl *typeDecl );
		virtual Declaration* mutate( TypedefDecl *typeDecl );

		virtual CompoundStmt * mutate( CompoundStmt * compoundStmt );

	  protected:
		bool inFunction;

		// to be added before block ends - use push_front so order is correct
		std::list< Statement * > destructorStmts;
	};

	void tweak( std::list< Declaration * > & translationUnit ) {
		RemoveInit::removeInitializers( translationUnit );
		CtorDtor::generateCtorDtor( translationUnit );
	}

	void RemoveInit::removeInitializers( std::list< Declaration * > & translationUnit ) {
		RemoveInit remover;
		mutateAll( translationUnit, remover );
	}

	RemoveInit::RemoveInit() : tempNamer( "_retVal" ) {}

	// in the case where an object has an initializer and a polymorphic type, insert an assignment immediately after the
	// declaration. This will (seemingly) cause the later phases to do the right thing with the assignment
	ObjectDecl *RemoveInit::mutate( ObjectDecl *objDecl ) {
		if (objDecl->get_init() && dynamic_cast<TypeInstType*>(objDecl->get_type())) {
			if (SingleInit * single = dynamic_cast<SingleInit*>(objDecl->get_init())) {
				// xxx this can be more complicated - consider ListInit
				UntypedExpr *assign = new UntypedExpr( new NameExpr( "?{}" ) );
				assign->get_args().push_back( new AddressExpr (new NameExpr( objDecl->get_name() ) ) );
				assign->get_args().push_back( single->get_value()->clone() );
				stmtsToAddAfter.push_back(new ExprStmt(noLabels, assign));
			} // if
		} // if
		return objDecl;
	}

	Statement *RemoveInit::mutate( ReturnStmt *returnStmt ) {
		// update for multiple return values
		assert( returnVals.size() == 0 || returnVals.size() == 1 );
		// hands off if the function returns an lvalue - we don't want to allocate a temporary if a variable's address
		// is being returned
		// xxx - this should construct rather than assign
		if ( returnStmt->get_expr() && returnVals.size() == 1 && funcName != "?=?" && ! returnVals.front()->get_type()->get_isLvalue()  ) {
			ObjectDecl *newObj = new ObjectDecl( tempNamer.newName(), DeclarationNode::NoStorageClass, LinkageSpec::C, 0, returnVals.front()->get_type()->clone(), 0 );
			stmtsToAdd.push_back( new DeclStmt( noLabels, newObj ) );

			UntypedExpr *assign = new UntypedExpr( new NameExpr( "?=?" ) );
			assign->get_args().push_back( new AddressExpr (new NameExpr( newObj->get_name() ) ) );
			assign->get_args().push_back( returnStmt->get_expr() );
			stmtsToAdd.push_back(new ExprStmt(noLabels, assign));

			returnStmt->set_expr( new VariableExpr( newObj ) );
		} // if
		return returnStmt;
	}

	DeclarationWithType* RemoveInit::mutate( FunctionDecl *functionDecl ) {
		std::list<DeclarationWithType*> oldReturnVals = returnVals;
		std::string oldFuncName = funcName;

		FunctionType * type = functionDecl->get_functionType();
		returnVals = type->get_returnVals();
		funcName = functionDecl->get_name();
		DeclarationWithType * decl = Mutator::mutate( functionDecl );
		returnVals = oldReturnVals;
		funcName = oldFuncName;
		return decl;
	}


	void CtorDtor::generateCtorDtor( std::list< Declaration * > & translationUnit ) {
		CtorDtor ctordtor;
		mutateAll( translationUnit, ctordtor );
	}

	namespace {
		bool tryConstruct( ObjectDecl * objDecl ) {
			// xxx - handle designations
			return ! LinkageSpec::isBuiltin( objDecl->get_linkage() ) &&
	 			(objDecl->get_init() == NULL ||
				( objDecl->get_init() != NULL && objDecl->get_init()->get_maybeConstructed() ));
		}

		Expression * makeCtorDtorExpr( std::string name, ObjectDecl * objDecl, std::list< Expression * > args ) {
			UntypedExpr * expr = new UntypedExpr( new NameExpr( name ) );
			expr->get_args().push_back( new AddressExpr( new VariableExpr( objDecl ) ) );
			expr->get_args().splice( expr->get_args().end(), args );
			return expr;
		}

		class InitExpander : public Visitor {
		  public:
		  InitExpander() {}
		  // ~InitExpander() {}
			virtual void visit( SingleInit * singleInit );
			virtual void visit( ListInit * listInit );
			std::list< Expression * > argList;
		};

		void InitExpander::visit( SingleInit * singleInit ) {
			argList.push_back( singleInit->get_value()->clone() );
		}

		void InitExpander::visit( ListInit * listInit ) {
			// xxx - for now, assume no nested list inits
			std::list<Initializer*>::iterator it = listInit->begin_initializers();
			for ( ; it != listInit->end_initializers(); ++it ) {
				(*it)->accept( *this );
			}
		}

		std::list< Expression * > makeInitList( Initializer * init ) {
			InitExpander expander;
			maybeAccept( init, expander );
			return expander.argList;
		}
	}

	ObjectDecl * CtorDtor::mutate( ObjectDecl * objDecl ) {
		// hands off if designated or if @=
		if ( tryConstruct( objDecl ) ) {
			if ( inFunction ) {
				Expression * ctor = makeCtorDtorExpr( "?{}", objDecl, makeInitList( objDecl->get_init() ) );
				Expression * dtor = makeCtorDtorExpr( "^?{}", objDecl, std::list< Expression * >() );

				// need to remember init expression, in case no ctors exist
				// if ctor does exist, want to use ctor expression instead of init
				// push this decision to the resolver
				objDecl->set_init( new ConstructorInit( ctor, objDecl->get_init() ) );
				destructorStmts.push_front( new ExprStmt( noLabels, dtor ) );
			} else {
				// xxx - find a way to construct/destruct globals
				// hack: implicit "static" initialization routine for each struct type? or something similar?
				// --ties into module system
			}
		}
		return objDecl;
	}

	DeclarationWithType * CtorDtor::mutate( FunctionDecl *functionDecl ) {
		// parameters should not be constructed and destructed, so don't mutate FunctionType
		bool oldInFunc = inFunction;
		mutateAll( functionDecl->get_oldDecls(), *this );
		inFunction = true;
		functionDecl->set_statements( maybeMutate( functionDecl->get_statements(), *this ) );
		inFunction = oldInFunc;
		return functionDecl;
	}

	CompoundStmt * CtorDtor::mutate( CompoundStmt * compoundStmt ) {
		CompoundStmt * ret = PolyMutator::mutate( compoundStmt );
		std::list< Statement * > &statements = ret->get_kids();
		if ( ! destructorStmts.empty() ) {
			// TODO: adding to the end of a block isn't sufficient, since
			// return/break/goto should trigger destructor when block is left.
			statements.splice( statements.end(), destructorStmts );
		} // if
		return ret;
	}

	// should not traverse into any of these declarations to find objects
	// that need to be constructed or destructed
	Declaration* CtorDtor::mutate( StructDecl *aggregateDecl ) { return aggregateDecl; }
	Declaration* CtorDtor::mutate( UnionDecl *aggregateDecl ) { return aggregateDecl; }
	Declaration* CtorDtor::mutate( EnumDecl *aggregateDecl ) { return aggregateDecl; }
	Declaration* CtorDtor::mutate( ContextDecl *aggregateDecl ) { return aggregateDecl; }
	TypeDecl* CtorDtor::mutate( TypeDecl *typeDecl ) { return typeDecl; }
	Declaration* CtorDtor::mutate( TypedefDecl *typeDecl ) { return typeDecl; }

} // namespace InitTweak

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