source: translator/ControlStruct/MLEMutator.cc @ 2c2242c

#include <cassert>
#include <algorithm>

#include "MLEMutator.h"
#include "SynTree/Statement.h"


namespace ControlStruct {
    MLEMutator::~MLEMutator() {
        delete targetTable;
        targetTable = 0;
    }

    CompoundStmt* MLEMutator::mutate( CompoundStmt *cmpndStmt ) {
        bool labeledBlock = false;
        if ( !((cmpndStmt->get_labels()).empty()) ) {
            labeledBlock = true;
            enclosingBlocks.push_back( Entry( cmpndStmt ) );
        }

        std::list< Statement * > &kids = cmpndStmt->get_kids();
        for ( std::list< Statement * >::iterator k = kids.begin(); k != kids.end(); k++ ) {
            *k = (*k)->acceptMutator(*this);

            if ( !get_breakLabel().empty() ) {
                std::list< Statement * >::iterator next = k; next++;
                if ( next == kids.end() ) {
                    std::list<Label> ls; ls.push_back( get_breakLabel() );
                    kids.push_back( new NullStmt( ls ) );
                } else
                    (*next)->get_labels().push_back( get_breakLabel() );

                set_breakLabel("");
            } // if
        } // for

        if ( labeledBlock ) {
            assert( ! enclosingBlocks.empty() );
            if ( ! enclosingBlocks.back().get_breakExit().empty() )
                set_breakLabel( enclosingBlocks.back().get_breakExit() );
            enclosingBlocks.pop_back();
        } // if

        //mutateAll( cmpndStmt->get_kids(), *this );
        return cmpndStmt;
    }

    Statement *MLEMutator::mutate( WhileStmt *whileStmt ) {
        enclosingLoops.push_back( Entry( whileStmt ) );
        whileStmt->set_body ( whileStmt->get_body()->acceptMutator( *this ) );

        Entry &e = enclosingLoops.back();
        assert ( e == whileStmt );
        whileStmt->set_body( mutateLoop( whileStmt->get_body(), e ) );
        enclosingLoops.pop_back();

        return whileStmt;
    }

    Statement *MLEMutator::mutate( ForStmt *forStmt ) {
        enclosingLoops.push_back( Entry( forStmt ) );
        maybeMutate( forStmt->get_body(), *this );

        Entry &e = enclosingLoops.back();
        assert ( e == forStmt );
        forStmt->set_body( mutateLoop( forStmt->get_body(), e ) );
        enclosingLoops.pop_back();

        return forStmt;
    }

    Statement *MLEMutator::mutate( BranchStmt *branchStmt ) throw ( SemanticError ) {
        if ( branchStmt->get_type() == BranchStmt::Goto )
            return branchStmt;

        // test if continue target is a loop
        if ( branchStmt->get_type() == BranchStmt::Continue && enclosingLoops.empty() )
            throw SemanticError( "'continue' outside a loop" );

        if ( branchStmt->get_type() == BranchStmt::Break && (enclosingLoops.empty() && enclosingSwitches.empty() && enclosingBlocks.empty() ) )
            throw SemanticError( "'break' outside a loop or switch" );

        if ( branchStmt->get_target() == "" ) return branchStmt;

        if ( targetTable->find( branchStmt->get_target() ) == targetTable->end() )
            throw SemanticError("The label defined in the exit loop statement does not exist." );  // shouldn't happen (since that's already checked)

        std::list< Entry >::iterator check;
        if ( ( check = std::find( enclosingLoops.begin(), enclosingLoops.end(), (*targetTable)[branchStmt->get_target()] ) ) == enclosingLoops.end() )
            // not in loop, checking if in block
            if ( (check = std::find( enclosingBlocks.begin(), enclosingBlocks.end(), (*targetTable)[branchStmt->get_target()] )) == enclosingBlocks.end() )
                // neither in loop nor in block, checking if in switch/choose
                if ( (check = std::find( enclosingSwitches.begin(), enclosingSwitches.end(), (*targetTable)[branchStmt->get_target()] )) == enclosingSwitches.end() )
                    throw SemanticError("The target specified in the exit loop statement does not correspond to an enclosing loop.");

        if ( enclosingLoops.back() == (*check) )
            return branchStmt;                          // exit the innermost loop (labels unnecessary)

        Label newLabel;
        switch( branchStmt->get_type() ) {
          case BranchStmt::Break:
            if ( check->get_breakExit() != "" )
                newLabel = check->get_breakExit();
            else {
                newLabel = generator->newLabel();
                check->set_breakExit( newLabel );
            } // if
            break;
          case BranchStmt::Continue:
            if ( check->get_contExit() != "" )
                newLabel = check->get_contExit();
            else {
                newLabel = generator->newLabel();
                check->set_contExit( newLabel );
            } // if
            break;
          default:
            return 0;                                   // shouldn't be here
        } // switch

        return new BranchStmt( std::list<Label>(), newLabel, BranchStmt::Goto );
    }


    Statement *MLEMutator::mutate( SwitchStmt *switchStmt ) {
        Label brkLabel = generator->newLabel();
        enclosingSwitches.push_back( Entry(switchStmt, "", brkLabel) );
        mutateAll( switchStmt->get_branches(), *this ); {
            // check if this is necessary (if there is a break to this point, otherwise do not generate
            std::list<Label> temp; temp.push_back( brkLabel );
            switchStmt->get_branches().push_back( new BranchStmt( temp, Label(""), BranchStmt::Break ) );
        }
        assert ( enclosingSwitches.back() == switchStmt );
        enclosingSwitches.pop_back();
        return switchStmt;
    }

    Statement *MLEMutator::mutate( ChooseStmt *switchStmt ) {
        Label brkLabel = generator->newLabel();
        enclosingSwitches.push_back( Entry(switchStmt,"", brkLabel) );
        mutateAll( switchStmt->get_branches(), *this ); {
            // check if this is necessary (if there is a break to this point, otherwise do not generate
            std::list<Label> temp; temp.push_back( brkLabel );
            switchStmt->get_branches().push_back( new BranchStmt( temp, Label(""), BranchStmt::Break ) );
        }
        assert ( enclosingSwitches.back() == switchStmt );
        enclosingSwitches.pop_back();
        return switchStmt;
    }

    Statement *MLEMutator::mutateLoop( Statement *bodyLoop, Entry &e ) {
        CompoundStmt *newBody;
        if ( ! (newBody = dynamic_cast<CompoundStmt *>( bodyLoop )) ) {
            newBody = new CompoundStmt( std::list< Label >() );
            newBody->get_kids().push_back( bodyLoop );
        } // if

        Label endLabel = e.get_contExit();

        if ( e.get_breakExit() != "" ) {
            if ( endLabel == "" ) endLabel = generator->newLabel();
            // check for whether this label is used or not, so as to not generate extraneous gotos
            if (e.breakExitUsed)
                newBody->get_kids().push_back( new BranchStmt( std::list< Label >(), endLabel, BranchStmt::Goto ) );
            // xxx
            //std::list< Label > ls; ls.push_back( e.get_breakExit() );
            set_breakLabel( e.get_breakExit() );
            //newBody->get_kids().push_back( new BranchStmt( ls, "", BranchStmt::Break ) );
        } // if

        if ( e.get_breakExit() != "" || e.get_contExit() != "" ){
            if (dynamic_cast< NullStmt *>( newBody->get_kids().back() ))
                newBody->get_kids().back()->get_labels().push_back( endLabel );
            else {
                std::list < Label > ls; ls.push_back( endLabel );
                newBody->get_kids().push_back( new NullStmt( ls ) );
            } // if
        } // if

        return newBody;
    }

    //*** Entry's methods
    void MLEMutator::Entry::set_contExit( Label l ) {
        assert ( contExit == "" || contExit == l );
        contExit = l;
    }

    void MLEMutator::Entry::set_breakExit( Label l ) {
        assert ( breakExit == "" || breakExit == l );
        breakExit = l;
    }
} // namespace ControlStruct