colobot/src/CBot/CBotCompExpr.cpp

// * This file is part of the COLOBOT source code
// * Copyright (C) 2001-2008, Daniel ROUX & EPSITEC SA, www.epsitec.ch
// *
// * This program is free software: you can redistribute it and/or modify
// * it under the terms of the GNU General Public License as published by
// * the Free Software Foundation, either version 3 of the License, or
// * (at your option) any later version.
// *
// * This program is distributed in the hope that it will be useful,
// * but WITHOUT ANY WARRANTY; without even the implied warranty of
// * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// * GNU General Public License for more details.
// *
// * You should have received a copy of the GNU General Public License
// * along with this program. If not, see  http://www.gnu.org/licenses/.

///////////////////////////////////////////////////
// expression of type Opérande1 > Opérande2
//                     Opérande1 != Opérande2
// etc.

#include "CBot.h"

// various constructeurs

CBotCompExpr::CBotCompExpr()
{
    m_leftop    =
    m_rightop   = NULL;
    name = "CBotCompExpr";
}

CBotCompExpr::~CBotCompExpr()
{
    delete  m_leftop;
    delete  m_rightop;
}

fichier plus utilise;

// compile instruction of type A < B

CBotInstr* CBotCompExpr::Compile(CBotToken* &p, CBotCStack* pStack)
{
    CBotCStack* pStk = pStack->AddStack();

    CBotInstr*  left = CBotAddExpr::Compile( p, pStk );     // expression A + B left
    if (left == NULL) return pStack->Return(NULL, pStk);    // error

    if ( p->GetType() == ID_HI ||
         p->GetType() == ID_LO ||
         p->GetType() == ID_HS ||
         p->GetType() == ID_LS ||
         p->GetType() == ID_EQ ||
         p->GetType() == ID_NE)                             // the various comparisons
    {
        CBotCompExpr* inst = new CBotCompExpr();            // element for operation
        inst->SetToken(p);                                  // stores the operation

        int          type1, type2;
        type1 = pStack->GetType();

        p = p->Next();
        if ( NULL != (inst->m_rightop = CBotAddExpr::Compile( p, pStk )) )  // expression A + B right
        {
            type2 = pStack->GetType();
            // are the results compatible
            if ( type1 == type2 )
            {
                inst->m_leftop = left;
                pStk->SetVar(new CBotVar(NULL, CBotTypBoolean));
                                                            // the result is a boolean
                return pStack->Return(inst, pStk);
            }
        }

        delete left;
        delete inst;
        return pStack->Return(NULL, pStk);
    }

    return pStack->Return(left, pStk);
}


// perform the operation

bool CBotCompExpr::Execute(CBotStack* &pStack)
{
    CBotStack* pStk1 = pStack->AddStack(this);
//  if ( pStk1 == EOX ) return TRUE;

    if ( pStk1->GetState() == 0 && !m_leftop->Execute(pStk1) ) return FALSE; // interrupted here ?

    pStk1->SetState(1);     // finished

    // requires a little more stack to not touch the result of the left
    CBotStack* pStk2 = pStk1->AddStack();

    if ( !m_rightop->Execute(pStk2) ) return FALSE; // interrupted here ?

    int     type1 = pStk1->GetType();
    int     type2 = pStk2->GetType();

    CBotVar*    result = new CBotVar( NULL, CBotTypBoolean );

    switch (GetTokenType())
    {
    case ID_LO:
        result->Lo(pStk1->GetVar(), pStk2->GetVar());       // lower
        break;
    case ID_HI:
        result->Hi(pStk1->GetVar(), pStk2->GetVar());       // higher
        break;
    case ID_LS:
        result->Ls(pStk1->GetVar(), pStk2->GetVar());       // lower or equal
        break;
    case ID_HS:
        result->Hs(pStk1->GetVar(), pStk2->GetVar());       // higher of equal
        break;
    case ID_EQ:
        result->Eq(pStk1->GetVar(), pStk2->GetVar());       // equal
        break;
    case ID_NE:
        result->Ne(pStk1->GetVar(), pStk2->GetVar());       // not equal
        break;
    }
    pStk2->SetVar(result);              // puts the result on the stack

    pStk1->Return(pStk2);               // frees the stack
    return pStack->Return(pStk1);       // transmit the result
}