source: translator/SymTab/Validate.cc @ 4bf5298

/*
  The "validate" phase of translation is used to take a syntax tree and convert it into a standard form that aims to be
  as regular in structure as possible.  Some assumptions can be made regarding the state of the tree after this pass is
  complete, including:

  - No nested structure or union definitions; any in the input are "hoisted" to the level of the containing struct or
    union.

  - All enumeration constants have type EnumInstType.

  - The type "void" never occurs in lists of function parameter or return types; neither do tuple types.  A function
    taking no arguments has no argument types, and tuples are flattened.

  - No context instances exist; they are all replaced by the set of declarations signified by the context, instantiated
    by the particular set of type arguments.

  - Every declaration is assigned a unique id.

  - No typedef declarations or instances exist; the actual type is substituted for each instance.

  - Each type, struct, and union definition is followed by an appropriate assignment operator.

  - Each use of a struct or union is connected to a complete definition of that struct or union, even if that definition
    occurs later in the input.
*/

#include <list>
#include <iterator>
#include "Validate.h"
#include "SynTree/Visitor.h"
#include "SynTree/Mutator.h"
#include "SynTree/Type.h"
#include "SynTree/Statement.h"
#include "Indexer.h"
#include "SynTree/TypeSubstitution.h"
#include "FixFunction.h"
#include "ImplementationType.h"
#include "utility.h"
#include "UniqueName.h"
#include "AddVisit.h"


#define debugPrint( x ) if ( doDebug ) { std::cout << x; }

namespace SymTab {
    class HoistStruct : public Visitor {
      public:
        static void hoistStruct( std::list< Declaration * > &translationUnit );
  
        std::list< Declaration * > &get_declsToAdd() { return declsToAdd; }
  
        virtual void visit( StructDecl *aggregateDecl );
        virtual void visit( UnionDecl *aggregateDecl );

        virtual void visit( CompoundStmt *compoundStmt );
        virtual void visit( IfStmt *ifStmt );
        virtual void visit( WhileStmt *whileStmt );
        virtual void visit( ForStmt *forStmt );
        virtual void visit( SwitchStmt *switchStmt );
        virtual void visit( ChooseStmt *chooseStmt );
        virtual void visit( CaseStmt *caseStmt );
        virtual void visit( CatchStmt *catchStmt );
      private:
        HoistStruct();

        template< typename AggDecl > void handleAggregate( AggDecl *aggregateDecl );

        std::list< Declaration * > declsToAdd;
        bool inStruct;
    };

    class Pass1 : public Visitor {
        typedef Visitor Parent;
        virtual void visit( EnumDecl *aggregateDecl );
        virtual void visit( FunctionType *func );
    };
  
    class Pass2 : public Indexer {
        typedef Indexer Parent;
      public:
        Pass2( bool doDebug, const Indexer *indexer );
      private:
        virtual void visit( StructInstType *structInst );
        virtual void visit( UnionInstType *unionInst );
        virtual void visit( ContextInstType *contextInst );
        virtual void visit( StructDecl *structDecl );
        virtual void visit( UnionDecl *unionDecl );
        virtual void visit( TypeInstType *typeInst );

        const Indexer *indexer;
  
        typedef std::map< std::string, std::list< StructInstType * > > ForwardStructsType;
        typedef std::map< std::string, std::list< UnionInstType * > > ForwardUnionsType;
        ForwardStructsType forwardStructs;
        ForwardUnionsType forwardUnions;
    };

    class Pass3 : public Indexer {
        typedef Indexer Parent;
      public:
        Pass3( const Indexer *indexer );
      private:
        virtual void visit( ObjectDecl *object );
        virtual void visit( FunctionDecl *func );

        const Indexer *indexer;
    };

    class AddStructAssignment : public Visitor {
      public:
        static void addStructAssignment( std::list< Declaration * > &translationUnit );

        std::list< Declaration * > &get_declsToAdd() { return declsToAdd; }
  
        virtual void visit( StructDecl *structDecl );
        virtual void visit( UnionDecl *structDecl );
        virtual void visit( TypeDecl *typeDecl );
        virtual void visit( ContextDecl *ctxDecl );
        virtual void visit( FunctionDecl *functionDecl );

        virtual void visit( FunctionType *ftype );
        virtual void visit( PointerType *ftype );
  
        virtual void visit( CompoundStmt *compoundStmt );
        virtual void visit( IfStmt *ifStmt );
        virtual void visit( WhileStmt *whileStmt );
        virtual void visit( ForStmt *forStmt );
        virtual void visit( SwitchStmt *switchStmt );
        virtual void visit( ChooseStmt *chooseStmt );
        virtual void visit( CaseStmt *caseStmt );
        virtual void visit( CatchStmt *catchStmt );

        AddStructAssignment() : functionNesting( 0 ) {}
      private:
        template< typename StmtClass > void visitStatement( StmtClass *stmt );
  
        std::list< Declaration * > declsToAdd;
        std::set< std::string > structsDone;
        unsigned int functionNesting;                   // current level of nested functions
    };

    class EliminateTypedef : public Mutator {
      public:
        static void eliminateTypedef( std::list< Declaration * > &translationUnit );
      private:
        virtual Declaration *mutate( TypedefDecl *typeDecl );
        virtual TypeDecl *mutate( TypeDecl *typeDecl );
        virtual DeclarationWithType *mutate( FunctionDecl *funcDecl );
        virtual ObjectDecl *mutate( ObjectDecl *objDecl );
        virtual CompoundStmt *mutate( CompoundStmt *compoundStmt );
        virtual Type *mutate( TypeInstType *aggregateUseType );
        virtual Expression *mutate( CastExpr *castExpr );
  
        std::map< std::string, TypedefDecl * > typedefNames;
    };

    void validate( std::list< Declaration * > &translationUnit, bool doDebug ) {
        Pass1 pass1;
        Pass2 pass2( doDebug, 0 );
        Pass3 pass3( 0 );
        EliminateTypedef::eliminateTypedef( translationUnit );
        HoistStruct::hoistStruct( translationUnit );
        acceptAll( translationUnit, pass1 );
        acceptAll( translationUnit, pass2 );
        AddStructAssignment::addStructAssignment( translationUnit );
        acceptAll( translationUnit, pass3 );
    }
    
    void validateType( Type *type, const Indexer *indexer ) {
        Pass1 pass1;
        Pass2 pass2( false, indexer );
        Pass3 pass3( indexer );
        type->accept( pass1 );
        type->accept( pass2 );
        type->accept( pass3 );
    }

    template< typename Visitor >
    void acceptAndAdd( std::list< Declaration * > &translationUnit, Visitor &visitor, bool addBefore ) {
        std::list< Declaration * >::iterator i = translationUnit.begin();
        while ( i != translationUnit.end() ) {
            (*i)->accept( visitor );
            std::list< Declaration * >::iterator next = i;
            next++;
            if ( ! visitor.get_declsToAdd().empty() ) {
                translationUnit.splice( addBefore ? i : next, visitor.get_declsToAdd() );
            } // if
            i = next;
        } // while
    }

    void HoistStruct::hoistStruct( std::list< Declaration * > &translationUnit ) {
        HoistStruct hoister;
        acceptAndAdd( translationUnit, hoister, true );
    }

    HoistStruct::HoistStruct() : inStruct( false ) {
    }

    void filter( std::list< Declaration * > &declList, bool (*pred)( Declaration * ), bool doDelete ) {
        std::list< Declaration * >::iterator i = declList.begin();
        while ( i != declList.end() ) {
            std::list< Declaration * >::iterator next = i;
            ++next;
            if ( pred( *i ) ) {
                if ( doDelete ) {
                    delete *i;
                } // if
                declList.erase( i );
            } // if
            i = next;
        } // while
    }

    bool isStructOrUnion( Declaration *decl ) {
        return dynamic_cast< StructDecl * >( decl ) || dynamic_cast< UnionDecl * >( decl );
    }

    template< typename AggDecl >
    void HoistStruct::handleAggregate( AggDecl *aggregateDecl ) {
        if ( inStruct ) {
            // Add elements in stack order corresponding to nesting structure.
            declsToAdd.push_front( aggregateDecl );
            Visitor::visit( aggregateDecl );
        } else {
            inStruct = true;
            Visitor::visit( aggregateDecl );
            inStruct = false;
        } // if
        // Always remove the hoisted aggregate from the inner structure.
        filter( aggregateDecl->get_members(), isStructOrUnion, false );
    }

    void HoistStruct::visit( StructDecl *aggregateDecl ) {
        handleAggregate( aggregateDecl );
    }

    void HoistStruct::visit( UnionDecl *aggregateDecl ) {
        handleAggregate( aggregateDecl );
    }

    void HoistStruct::visit( CompoundStmt *compoundStmt ) {
        addVisit( compoundStmt, *this );
    }

    void HoistStruct::visit( IfStmt *ifStmt ) {
        addVisit( ifStmt, *this );
    }

    void HoistStruct::visit( WhileStmt *whileStmt ) {
        addVisit( whileStmt, *this );
    }

    void HoistStruct::visit( ForStmt *forStmt ) {
        addVisit( forStmt, *this );
    }

    void HoistStruct::visit( SwitchStmt *switchStmt ) {
        addVisit( switchStmt, *this );
    }

    void HoistStruct::visit( ChooseStmt *switchStmt ) {
        addVisit( switchStmt, *this );
    }

    void HoistStruct::visit( CaseStmt *caseStmt ) {
        addVisit( caseStmt, *this );
    }

    void HoistStruct::visit( CatchStmt *cathStmt ) {
        addVisit( cathStmt, *this );
    }

    void Pass1::visit( EnumDecl *enumDecl ) {
        // Set the type of each member of the enumeration to be EnumConstant
  
        for ( std::list< Declaration * >::iterator i = enumDecl->get_members().begin(); i != enumDecl->get_members().end(); ++i ) {
            ObjectDecl *obj = dynamic_cast< ObjectDecl * >( *i );
            assert( obj );
            obj->set_type( new EnumInstType( Type::Qualifiers( true, false, false, false, false, false ), enumDecl->get_name() ) );
        } // for
        Parent::visit( enumDecl );
    }

    namespace {
        template< typename DWTIterator >
        void fixFunctionList( DWTIterator begin, DWTIterator end, FunctionType *func ) {
            // the only case in which "void" is valid is where it is the only one in the list; then
            // it should be removed entirely
            // other fix ups are handled by the FixFunction class
            if ( begin == end ) return;
            FixFunction fixer;
            DWTIterator i = begin;
            *i = (*i )->acceptMutator( fixer );
            if ( fixer.get_isVoid() ) {
                DWTIterator j = i;
                ++i;
                func->get_parameters().erase( j );
                if ( i != end ) { 
                    throw SemanticError( "invalid type void in function type ", func );
                } // if
            } else {
                ++i;
                for ( ; i != end; ++i ) {
                    FixFunction fixer;
                    *i = (*i )->acceptMutator( fixer );
                    if ( fixer.get_isVoid() ) {
                        throw SemanticError( "invalid type void in function type ", func );
                    } // if
                } // for
            } // if
        }
    }

    void Pass1::visit( FunctionType *func ) {
        // Fix up parameters and return types
        fixFunctionList( func->get_parameters().begin(), func->get_parameters().end(), func );
        fixFunctionList( func->get_returnVals().begin(), func->get_returnVals().end(), func );
        Visitor::visit( func );
    }

    Pass2::Pass2( bool doDebug, const Indexer *other_indexer ) : Indexer( doDebug ) {
        if ( other_indexer ) {
            indexer = other_indexer;
        } else {
            indexer = this;
        } // if
    }

    void Pass2::visit( StructInstType *structInst ) {
        Parent::visit( structInst );
        StructDecl *st = indexer->lookupStruct( structInst->get_name() );
        // it's not a semantic error if the struct is not found, just an implicit forward declaration
        if ( st ) {
            assert( ! structInst->get_baseStruct() || structInst->get_baseStruct()->get_members().empty() || ! st->get_members().empty() );
            structInst->set_baseStruct( st );
        } // if
        if ( ! st || st->get_members().empty() ) {
            // use of forward declaration
            forwardStructs[ structInst->get_name() ].push_back( structInst );
        } // if
    }

    void Pass2::visit( UnionInstType *unionInst ) {
        Parent::visit( unionInst );
        UnionDecl *un = indexer->lookupUnion( unionInst->get_name() );
        // it's not a semantic error if the union is not found, just an implicit forward declaration
        if ( un ) {
            unionInst->set_baseUnion( un );
        } // if
        if ( ! un || un->get_members().empty() ) {
            // use of forward declaration
            forwardUnions[ unionInst->get_name() ].push_back( unionInst );
        } // if
    }

    void Pass2::visit( ContextInstType *contextInst ) {
        Parent::visit( contextInst );
        ContextDecl *ctx = indexer->lookupContext( contextInst->get_name() );
        if ( ! ctx ) {
            throw SemanticError( "use of undeclared context " + contextInst->get_name() );
        } // if
        for ( std::list< TypeDecl * >::const_iterator i = ctx->get_parameters().begin(); i != ctx->get_parameters().end(); ++i ) {
            for ( std::list< DeclarationWithType * >::const_iterator assert = (*i )->get_assertions().begin(); assert != (*i )->get_assertions().end(); ++assert ) {
                if ( ContextInstType *otherCtx = dynamic_cast< ContextInstType * >(*assert ) ) {
                    cloneAll( otherCtx->get_members(), contextInst->get_members() );
                } else {
                    contextInst->get_members().push_back( (*assert )->clone() );
                } // if
            } // for
        } // for
        applySubstitution( ctx->get_parameters().begin(), ctx->get_parameters().end(), contextInst->get_parameters().begin(), ctx->get_members().begin(), ctx->get_members().end(), back_inserter( contextInst->get_members() ) );
    }

    void Pass2::visit( StructDecl *structDecl ) {
        if ( ! structDecl->get_members().empty() ) {
            ForwardStructsType::iterator fwds = forwardStructs.find( structDecl->get_name() );
            if ( fwds != forwardStructs.end() ) {
                for ( std::list< StructInstType * >::iterator inst = fwds->second.begin(); inst != fwds->second.end(); ++inst ) {
                    (*inst )->set_baseStruct( structDecl );
                } // for
                forwardStructs.erase( fwds );
            } // if
        } // if
        Indexer::visit( structDecl );
    }

    void Pass2::visit( UnionDecl *unionDecl ) {
        if ( ! unionDecl->get_members().empty() ) {
            ForwardUnionsType::iterator fwds = forwardUnions.find( unionDecl->get_name() );
            if ( fwds != forwardUnions.end() ) {
                for ( std::list< UnionInstType * >::iterator inst = fwds->second.begin(); inst != fwds->second.end(); ++inst ) {
                    (*inst )->set_baseUnion( unionDecl );
                } // for
                forwardUnions.erase( fwds );
            } // if
        } // if
        Indexer::visit( unionDecl );
    }

    void Pass2::visit( TypeInstType *typeInst ) {
        if ( NamedTypeDecl *namedTypeDecl = lookupType( typeInst->get_name() ) ) {
            if ( TypeDecl *typeDecl = dynamic_cast< TypeDecl * >( namedTypeDecl ) ) {
                typeInst->set_isFtype( typeDecl->get_kind() == TypeDecl::Ftype );
            } // if
        } // if
    }

    Pass3::Pass3( const Indexer *other_indexer ) :  Indexer( false ) {
        if ( other_indexer ) {
            indexer = other_indexer;
        } else {
            indexer = this;
        } // if
    }

    void forallFixer( Type *func ) {
        // Fix up assertions
        for ( std::list< TypeDecl * >::iterator type = func->get_forall().begin(); type != func->get_forall().end(); ++type ) {
            std::list< DeclarationWithType * > toBeDone, nextRound;
            toBeDone.splice( toBeDone.end(), (*type )->get_assertions() );
            while ( ! toBeDone.empty() ) {
                for ( std::list< DeclarationWithType * >::iterator assertion = toBeDone.begin(); assertion != toBeDone.end(); ++assertion ) {
                    if ( ContextInstType *ctx = dynamic_cast< ContextInstType * >( (*assertion )->get_type() ) ) {
                        for ( std::list< Declaration * >::const_iterator i = ctx->get_members().begin(); i != ctx->get_members().end(); ++i ) {
                            DeclarationWithType *dwt = dynamic_cast< DeclarationWithType * >( *i );
                            assert( dwt );
                            nextRound.push_back( dwt->clone() );
                        }
                        delete ctx;
                    } else {
                        FixFunction fixer;
                        *assertion = (*assertion )->acceptMutator( fixer );
                        if ( fixer.get_isVoid() ) {
                            throw SemanticError( "invalid type void in assertion of function ", func );
                        }
                        (*type )->get_assertions().push_back( *assertion );
                    }
                }
                toBeDone.clear();
                toBeDone.splice( toBeDone.end(), nextRound );
            }
        }
    }

    void Pass3::visit( ObjectDecl *object ) {
        forallFixer( object->get_type() );
        if ( PointerType *pointer = dynamic_cast< PointerType * >( object->get_type() ) ) {
            forallFixer( pointer->get_base() );
        } // if
        Parent::visit( object );
        object->fixUniqueId();
    }

    void Pass3::visit( FunctionDecl *func ) {
        forallFixer( func->get_type() );
        Parent::visit( func );
        func->fixUniqueId();
    }

    static const std::list< std::string > noLabels;

    void AddStructAssignment::addStructAssignment( std::list< Declaration * > &translationUnit ) {
        AddStructAssignment visitor;
        acceptAndAdd( translationUnit, visitor, false );
    }

    template< typename OutputIterator >
    void makeScalarAssignment( ObjectDecl *srcParam, ObjectDecl *dstParam, DeclarationWithType *member, OutputIterator out ) {
        ObjectDecl *obj = dynamic_cast<ObjectDecl *>( member );
        // unnamed bit fields are not copied as they cannot be accessed
        if ( obj != NULL && obj->get_name() == "" && obj->get_bitfieldWidth() != NULL ) return;

        UntypedExpr *assignExpr = new UntypedExpr( new NameExpr( "?=?" ) );
  
        UntypedExpr *derefExpr = new UntypedExpr( new NameExpr( "*?" ) );
        derefExpr->get_args().push_back( new VariableExpr( dstParam ) );
  
        // do something special for unnamed members
        Expression *dstselect = new AddressExpr( new MemberExpr( member, derefExpr ) );
        assignExpr->get_args().push_back( dstselect );
  
        Expression *srcselect = new MemberExpr( member, new VariableExpr( srcParam ) );
        assignExpr->get_args().push_back( srcselect );
  
        *out++ = new ExprStmt( noLabels, assignExpr );
    }

    template< typename OutputIterator >
    void makeArrayAssignment( ObjectDecl *srcParam, ObjectDecl *dstParam, DeclarationWithType *member, ArrayType *array, OutputIterator out ) {
        static UniqueName indexName( "_index" );
  
        // for a flexible array member nothing is done -- user must define own assignment
        if ( ! array->get_dimension() ) return;
  
        ObjectDecl *index = new ObjectDecl( indexName.newName(), Declaration::NoStorageClass, LinkageSpec::C, 0, new BasicType( Type::Qualifiers(), BasicType::SignedInt ), 0 );
        *out++ = new DeclStmt( noLabels, index );
  
        UntypedExpr *init = new UntypedExpr( new NameExpr( "?=?" ) );
        init->get_args().push_back( new AddressExpr( new VariableExpr( index ) ) );
        init->get_args().push_back( new NameExpr( "0" ) );
        Statement *initStmt = new ExprStmt( noLabels, init );
  
        UntypedExpr *cond = new UntypedExpr( new NameExpr( "?<?" ) );
        cond->get_args().push_back( new VariableExpr( index ) );
        cond->get_args().push_back( array->get_dimension()->clone() );
  
        UntypedExpr *inc = new UntypedExpr( new NameExpr( "++?" ) );
        inc->get_args().push_back( new AddressExpr( new VariableExpr( index ) ) );
  
        UntypedExpr *assignExpr = new UntypedExpr( new NameExpr( "?=?" ) );
  
        UntypedExpr *derefExpr = new UntypedExpr( new NameExpr( "*?" ) );
        derefExpr->get_args().push_back( new VariableExpr( dstParam ) );
  
        Expression *dstselect = new MemberExpr( member, derefExpr );
        UntypedExpr *dstIndex = new UntypedExpr( new NameExpr( "?+?" ) );
        dstIndex->get_args().push_back( dstselect );
        dstIndex->get_args().push_back( new VariableExpr( index ) );
        assignExpr->get_args().push_back( dstIndex );
  
        Expression *srcselect = new MemberExpr( member, new VariableExpr( srcParam ) );
        UntypedExpr *srcIndex = new UntypedExpr( new NameExpr( "?[?]" ) );
        srcIndex->get_args().push_back( srcselect );
        srcIndex->get_args().push_back( new VariableExpr( index ) );
        assignExpr->get_args().push_back( srcIndex );
  
        *out++ = new ForStmt( noLabels, initStmt, cond, inc, new ExprStmt( noLabels, assignExpr ) );
    }

    Declaration *makeStructAssignment( StructDecl *aggregateDecl, StructInstType *refType, unsigned int functionNesting ) {
        FunctionType *assignType = new FunctionType( Type::Qualifiers(), false );
  
        ObjectDecl *returnVal = new ObjectDecl( "", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, refType->clone(), 0 );
        assignType->get_returnVals().push_back( returnVal );
  
        ObjectDecl *dstParam = new ObjectDecl( "_dst", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), refType->clone() ), 0 );
        assignType->get_parameters().push_back( dstParam );
  
        ObjectDecl *srcParam = new ObjectDecl( "_src", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, refType, 0 );
        assignType->get_parameters().push_back( srcParam );

        // Routines at global scope marked "static" to prevent multiple definitions is separate translation units
        // because each unit generates copies of the default routines for each aggregate.
        FunctionDecl *assignDecl = new FunctionDecl( "?=?", functionNesting > 0 ? Declaration::NoStorageClass : Declaration::Static, LinkageSpec::AutoGen, assignType, new CompoundStmt( noLabels ), true );
        assignDecl->fixUniqueId();
  
        for ( std::list< Declaration * >::const_iterator member = aggregateDecl->get_members().begin(); member != aggregateDecl->get_members().end(); ++member ) {
            if ( DeclarationWithType *dwt = dynamic_cast< DeclarationWithType * >( *member ) ) {
                if ( ArrayType *array = dynamic_cast< ArrayType * >( dwt->get_type() ) ) {
                    makeArrayAssignment( srcParam, dstParam, dwt, array, back_inserter( assignDecl->get_statements()->get_kids() ) );
                } else {
                    makeScalarAssignment( srcParam, dstParam, dwt, back_inserter( assignDecl->get_statements()->get_kids() ) );
                } // if
            } // if
        } // for
        assignDecl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );
  
        return assignDecl;
    }

    Declaration *makeUnionAssignment( UnionDecl *aggregateDecl, UnionInstType *refType, unsigned int functionNesting ) {
        FunctionType *assignType = new FunctionType( Type::Qualifiers(), false );
  
        ObjectDecl *returnVal = new ObjectDecl( "", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, refType->clone(), 0 );
        assignType->get_returnVals().push_back( returnVal );
  
        ObjectDecl *dstParam = new ObjectDecl( "_dst", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), refType->clone() ), 0 );
        assignType->get_parameters().push_back( dstParam );
  
        ObjectDecl *srcParam = new ObjectDecl( "_src", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, refType, 0 );
        assignType->get_parameters().push_back( srcParam );
  
        // Routines at global scope marked "static" to prevent multiple definitions is separate translation units
        // because each unit generates copies of the default routines for each aggregate.
        FunctionDecl *assignDecl = new FunctionDecl( "?=?",  functionNesting > 0 ? Declaration::NoStorageClass : Declaration::Static, LinkageSpec::AutoGen, assignType, new CompoundStmt( noLabels ), true );
        assignDecl->fixUniqueId();
  
        UntypedExpr *copy = new UntypedExpr( new NameExpr( "__builtin_memcpy" ) );
        copy->get_args().push_back( new VariableExpr( dstParam ) );
        copy->get_args().push_back( new AddressExpr( new VariableExpr( srcParam ) ) );
        copy->get_args().push_back( new SizeofExpr( refType->clone() ) );

        assignDecl->get_statements()->get_kids().push_back( new ExprStmt( noLabels, copy ) );
        assignDecl->get_statements()->get_kids().push_back( new ReturnStmt( noLabels, new VariableExpr( srcParam ) ) );
  
        return assignDecl;
    }

    void AddStructAssignment::visit( StructDecl *structDecl ) {
        if ( ! structDecl->get_members().empty() && structsDone.find( structDecl->get_name() ) == structsDone.end() ) {
            StructInstType *structInst = new StructInstType( Type::Qualifiers(), structDecl->get_name() );
            structInst->set_baseStruct( structDecl );
            declsToAdd.push_back( makeStructAssignment( structDecl, structInst, functionNesting ) );
            structsDone.insert( structDecl->get_name() );
        } // if
    }

    void AddStructAssignment::visit( UnionDecl *unionDecl ) {
        if ( ! unionDecl->get_members().empty() ) {
            UnionInstType *unionInst = new UnionInstType( Type::Qualifiers(), unionDecl->get_name() );
            unionInst->set_baseUnion( unionDecl );
            declsToAdd.push_back( makeUnionAssignment( unionDecl, unionInst, functionNesting ) );
        } // if
    }

    void AddStructAssignment::visit( TypeDecl *typeDecl ) {
        CompoundStmt *stmts = 0;
        TypeInstType *typeInst = new TypeInstType( Type::Qualifiers(), typeDecl->get_name(), false );
        typeInst->set_baseType( typeDecl );
        ObjectDecl *src = new ObjectDecl( "_src", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, typeInst->clone(), 0 );
        ObjectDecl *dst = new ObjectDecl( "_dst", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, new PointerType( Type::Qualifiers(), typeInst->clone() ), 0 );
        if ( typeDecl->get_base() ) {
            stmts = new CompoundStmt( std::list< Label >() );
            UntypedExpr *assign = new UntypedExpr( new NameExpr( "?=?" ) );
            assign->get_args().push_back( new CastExpr( new VariableExpr( dst ), new PointerType( Type::Qualifiers(), typeDecl->get_base()->clone() ) ) );
            assign->get_args().push_back( new CastExpr( new VariableExpr( src ), typeDecl->get_base()->clone() ) );
            stmts->get_kids().push_back( new ReturnStmt( std::list< Label >(), assign ) );
        } // if
        FunctionType *type = new FunctionType( Type::Qualifiers(), false );
        type->get_returnVals().push_back( new ObjectDecl( "", Declaration::NoStorageClass, LinkageSpec::Cforall, 0, typeInst, 0 ) );
        type->get_parameters().push_back( dst );
        type->get_parameters().push_back( src );
        FunctionDecl *func = new FunctionDecl( "?=?", Declaration::NoStorageClass, LinkageSpec::AutoGen, type, stmts, false );
        declsToAdd.push_back( func );
    }

    void addDecls( std::list< Declaration * > &declsToAdd, std::list< Statement * > &statements, std::list< Statement * >::iterator i ) {
        if ( ! declsToAdd.empty() ) {
            for ( std::list< Declaration * >::iterator decl = declsToAdd.begin(); decl != declsToAdd.end(); ++decl ) {
                statements.insert( i, new DeclStmt( noLabels, *decl ) );
            } // for
            declsToAdd.clear();
        } // if
    }

    void AddStructAssignment::visit( FunctionType *) {
        // ensure that we don't add assignment ops for types defined as part of the function
    }

    void AddStructAssignment::visit( PointerType *) {
        // ensure that we don't add assignment ops for types defined as part of the pointer
    }

    void AddStructAssignment::visit( ContextDecl *) {
        // ensure that we don't add assignment ops for types defined as part of the context
    }

    template< typename StmtClass >
    inline void AddStructAssignment::visitStatement( StmtClass *stmt ) {
        std::set< std::string > oldStructs = structsDone;
        addVisit( stmt, *this );
        structsDone = oldStructs;
    }

    void AddStructAssignment::visit( FunctionDecl *functionDecl ) {
        maybeAccept( functionDecl->get_functionType(), *this );
        acceptAll( functionDecl->get_oldDecls(), *this );
        functionNesting += 1;
        maybeAccept( functionDecl->get_statements(), *this );
        functionNesting -= 1;
    }

    void AddStructAssignment::visit( CompoundStmt *compoundStmt ) {
        visitStatement( compoundStmt );
    }

    void AddStructAssignment::visit( IfStmt *ifStmt ) {
        visitStatement( ifStmt );
    }

    void AddStructAssignment::visit( WhileStmt *whileStmt ) {
        visitStatement( whileStmt );
    }

    void AddStructAssignment::visit( ForStmt *forStmt ) {
        visitStatement( forStmt );
    }

    void AddStructAssignment::visit( SwitchStmt *switchStmt ) {
        visitStatement( switchStmt );
    }

    void AddStructAssignment::visit( ChooseStmt *switchStmt ) {
        visitStatement( switchStmt );
    }

    void AddStructAssignment::visit( CaseStmt *caseStmt ) {
        visitStatement( caseStmt );
    }

    void AddStructAssignment::visit( CatchStmt *cathStmt ) {
        visitStatement( cathStmt );
    }

    bool isTypedef( Declaration *decl ) {
        return dynamic_cast< TypedefDecl * >( decl );
    }

    void EliminateTypedef::eliminateTypedef( std::list< Declaration * > &translationUnit ) {
        EliminateTypedef eliminator;
        mutateAll( translationUnit, eliminator );
        filter( translationUnit, isTypedef, true );
    }

    Type *EliminateTypedef::mutate( TypeInstType *typeInst ) {
        std::map< std::string, TypedefDecl * >::const_iterator def = typedefNames.find( typeInst->get_name() );
        if ( def != typedefNames.end() ) {
            Type *ret = def->second->get_base()->clone();
            ret->get_qualifiers() += typeInst->get_qualifiers();
            delete typeInst;
            return ret;
        } // if
        return typeInst;
    }

    Declaration *EliminateTypedef::mutate( TypedefDecl *tyDecl ) {
        Declaration *ret = Mutator::mutate( tyDecl );
        typedefNames[ tyDecl->get_name() ] = tyDecl;
        // When a typedef is a forward declaration:
        //    typedef struct screen SCREEN;
        // the declaration portion must be retained:
        //    struct screen;
        // because the expansion of the typedef is:
        //    void rtn( SCREEN *p ) => void rtn( struct screen *p )
        // hence the type-name "screen" must be defined.
        // Note, qualifiers on the typedef are superfluous for the forward declaration.
        if ( StructInstType *aggDecl = dynamic_cast< StructInstType * >( tyDecl->get_base() ) ) {
            return new StructDecl( aggDecl->get_name() );
        } else if ( UnionInstType *aggDecl = dynamic_cast< UnionInstType * >( tyDecl->get_base() ) ) {
            return new UnionDecl( aggDecl->get_name() );
        } else {
            return ret;
        } // if
    }

    TypeDecl *EliminateTypedef::mutate( TypeDecl *typeDecl ) {
        std::map< std::string, TypedefDecl * >::iterator i = typedefNames.find( typeDecl->get_name() );
        if ( i != typedefNames.end() ) {
            typedefNames.erase( i ) ;
        } // if
        return typeDecl;
    }

    DeclarationWithType *EliminateTypedef::mutate( FunctionDecl *funcDecl ) {
        std::map< std::string, TypedefDecl * > oldNames = typedefNames;
        DeclarationWithType *ret = Mutator::mutate( funcDecl );
        typedefNames = oldNames;
        return ret;
    }

    ObjectDecl *EliminateTypedef::mutate( ObjectDecl *objDecl ) {
        std::map< std::string, TypedefDecl * > oldNames = typedefNames;
        ObjectDecl *ret = Mutator::mutate( objDecl );
        typedefNames = oldNames;
        return ret;
    }

    Expression *EliminateTypedef::mutate( CastExpr *castExpr ) {
        std::map< std::string, TypedefDecl * > oldNames = typedefNames;
        Expression *ret = Mutator::mutate( castExpr );
        typedefNames = oldNames;
        return ret;
    }

    CompoundStmt *EliminateTypedef::mutate( CompoundStmt *compoundStmt ) {
        std::map< std::string, TypedefDecl * > oldNames = typedefNames;
        CompoundStmt *ret = Mutator::mutate( compoundStmt );
        std::list< Statement * >::iterator i = compoundStmt->get_kids().begin();
        while ( i != compoundStmt->get_kids().end() ) {
            std::list< Statement * >::iterator next = i;
            ++next;
            if ( DeclStmt *declStmt = dynamic_cast< DeclStmt * >( *i ) ) {
                if ( dynamic_cast< TypedefDecl * >( declStmt->get_decl() ) ) {
                    delete *i;
                    compoundStmt->get_kids().erase( i );
                } // if
            } // if
            i = next;
        } // while
        typedefNames = oldNames;
        return ret;
    }
} // namespace SymTab