harbour-core/harbour/include/hbexprc.c

/*
 * $Id$
 */

/*
 * Harbour Project source code:
 * Compiler Expression Optimizer - utilities
 *
 * Copyright 1999 Ryszard Glab
 * www - http://www.harbour-project.org
 *
 * 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 2 of the License, or
 * (at your option) any later version, with one exception:
 *
 * The exception is that if you link the Harbour Runtime Library (HRL)
 * and/or the Harbour Virtual Machine (HVM) with other files to produce
 * an executable, this does not by itself cause the resulting executable
 * to be covered by the GNU General Public License. Your use of that
 * executable is in no way restricted on account of linking the HRL
 * and/or HVM code into it.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA (or visit
 * their web site at http://www.gnu.org/).
 *
 */

/* TOFIX: Split the code, since MSC8 can't compile it, even in Huge model. */

/* TODO:
 *    - Correct post- and pre- operations to correctly handle the following code
 *    a[ i++ ]++
 *    Notice: in current implementation (an in Clipper too) 'i++' is evaluated
 *    two times! This causes that the new value (after incrementation) is
 *    stored in next element of the array.
 */

#include <math.h>
#include "hbcomp.h"

/* ************************************************************************* */

#if defined( HB_MACRO_SUPPORT )
void hb_compExprDelOperator( HB_EXPR_PTR pExpr, HB_MACRO_DECL )
#else
void hb_compExprDelOperator( HB_EXPR_PTR pExpr )
#endif
{
   if( pExpr->value.asOperator.pLeft )
      HB_EXPR_PCODE1( hb_compExprDelete, pExpr->value.asOperator.pLeft );
   if( pExpr->value.asOperator.pRight )
      HB_EXPR_PCODE1( hb_compExprDelete, pExpr->value.asOperator.pRight );
}


/* Generates pcodes for compound operators    += -= *= /= %= ^=
 *
 * pExpr is an expression created by hb_compExprNew<operator>Eq functions
 */
#if defined( HB_MACRO_SUPPORT )
void hb_compExprPushOperEq( HB_EXPR_PTR pSelf, BYTE bOpEq, HB_MACRO_DECL )
#else
void hb_compExprPushOperEq( HB_EXPR_PTR pSelf, BYTE bOpEq )
#endif
{
   /* NOTE: an object instance variable needs special handling
    */
   if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
   {
      HB_EXPR_PTR pObj = pSelf->value.asOperator.pLeft;

      /* Push object */
      HB_EXPR_USE( pObj->value.asMessage.pObject, HB_EA_PUSH_PCODE );
      /* Push _message for later use  */
      HB_EXPR_PCODE1( hb_compGenMessageData, pObj->value.asMessage.szMessage );

      /* Now push current value of variable */
#ifdef HB_C52_STRICT
      /* push object */
      HB_EXPR_USE( pObj->value.asMessage.pObject, HB_EA_PUSH_PCODE );
#else
      /* NOTE: this duplicate optimization requires that HB_P_MESSAGE
       * reverts items on the stack !
       * duplicate object on the stack
       */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_DUPLICATE );
#endif
      /* now send the message */
      HB_EXPR_PCODE1( hb_compGenMessage, pObj->value.asMessage.szMessage );
      HB_EXPR_PCODE3( hb_compGenPCode3, HB_P_FUNCTION, 0, 0 );

/* NOTE: COMPATIBILITY ISSUE:
 *  The above HB_C52_STRICT setting determines
 * the way the chained send messages are handled.
 * For example, the following code:
 *
 * a:b( COUNT() ):c += 1
 *
 * will be handled as:
 *
 * a:b( COUNT() ):c := a:b( COUNT() ):c + 1
 *
 * in strict Clipper compatibility mode and
 *
 * temp := a:b( COUNT() ), temp:c += 1
 *
 * in non-strict mode.
 *   In practice in Clipper it will call COUNT() function two times: the
 * first time before addition and the second one after addition - in Harbour,
 * COUNT() function will be called only once, before addition.
 * The Harbour (non-strict) method is:
 * 1) faster
 * 2) it guarantees that the same instance variable of the same object will
 *   be changed
 */

      /* push increment value */
      HB_EXPR_USE( pSelf->value.asOperator.pRight, HB_EA_PUSH_PCODE );
      /* increase operation */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOpEq );

      /* call pop message with one argument */
      HB_EXPR_PCODE3( hb_compGenPCode3, HB_P_FUNCTION, 1, 0 );
   }
   /* TODO: add a special code for arrays to correctly handle a[ i++ ]++
    */
   else
   {
      /* push old value */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_PUSH_PCODE );
      /* push increment value */
      HB_EXPR_USE( pSelf->value.asOperator.pRight, HB_EA_PUSH_PCODE );
      /* perform operation and duplicate the new value */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOpEq );
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_DUPLICATE );
      /* pop the new value into variable and leave the copy on the stack */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_POP_PCODE );
   }
}

/* Generates pcodes for <operator>= syntax
 * used standalone as a statement (it cannot leave the value on the stack)
 */
#if defined( HB_MACRO_SUPPORT )
void hb_compExprUseOperEq( HB_EXPR_PTR pSelf, BYTE bOpEq, HB_MACRO_DECL )
#else
void hb_compExprUseOperEq( HB_EXPR_PTR pSelf, BYTE bOpEq )
#endif
{
   /* NOTE: an object instance variable needs special handling
    */
   if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
   {
      HB_EXPR_PTR pObj = pSelf->value.asOperator.pLeft;

      /* Push object */
      HB_EXPR_USE( pObj->value.asMessage.pObject, HB_EA_PUSH_PCODE );
      /* Push _message for later use  */
      HB_EXPR_PCODE1( hb_compGenMessageData, pObj->value.asMessage.szMessage );

      /* Now push current value of variable */
#ifdef HB_C52_STRICT
      /* push object */
      HB_EXPR_USE( pObj->value.asMessage.pObject, HB_EA_PUSH_PCODE );
#else
      /* duplicate object on the stack */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_DUPLICATE );
#endif
      /* now send the message */
      HB_EXPR_PCODE1( hb_compGenMessage, pObj->value.asMessage.szMessage );
      HB_EXPR_PCODE3( hb_compGenPCode3, HB_P_FUNCTION, 0, 0 );

      /* push increment value */
      HB_EXPR_USE( pSelf->value.asOperator.pRight, HB_EA_PUSH_PCODE );
      /* increase operation */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOpEq );

      /* call pop message with one argument */
      HB_EXPR_PCODE3( hb_compGenPCode3, HB_P_FUNCTION, 1, 0 );
      /* pop the value from the stack */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_POP );
   }
   else
   {
      /* push old value */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_PUSH_PCODE );
      /* push increment value */
      HB_EXPR_USE( pSelf->value.asOperator.pRight, HB_EA_PUSH_PCODE );
      /* add */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOpEq );
      /* pop the new value into variable and remove it from the stack */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_POP_PCODE );
   }
}

/* Generates the pcodes for pre- increment/decrement expressions
 */
#if defined( HB_MACRO_SUPPORT )
void hb_compExprPushPreOp( HB_EXPR_PTR pSelf, BYTE bOper, HB_MACRO_DECL )
#else
void hb_compExprPushPreOp( HB_EXPR_PTR pSelf, BYTE bOper )
#endif
{
   /* NOTE: an object instance variable needs special handling
    */
   if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
   {
      HB_EXPR_PTR pObj = pSelf->value.asOperator.pLeft;

      /* Push object */
      HB_EXPR_USE( pObj->value.asMessage.pObject, HB_EA_PUSH_PCODE );
      /* Push _message for later use */
      HB_EXPR_PCODE1( hb_compGenMessageData, pObj->value.asMessage.szMessage );

      /* Now push current value of variable */
#ifdef HB_C52_STRICT
      /* push object */
      HB_EXPR_USE( pObj->value.asMessage.pObject, HB_EA_PUSH_PCODE );
#else
      /* duplicate object on the stack */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_DUPLICATE );
#endif
      /* now send the message */
      HB_EXPR_PCODE1( hb_compGenMessage, pObj->value.asMessage.szMessage );
      HB_EXPR_PCODE3( hb_compGenPCode3, HB_P_FUNCTION, 0, 0 );

      /* increase/decrease operation */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOper );

      /* call pop message with one argument - it leaves the value on the stack */
      HB_EXPR_PCODE3( hb_compGenPCode3, HB_P_FUNCTION, 1, 0 );
   }
   else
   {
      /* Push current value */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_PUSH_PCODE );
      /* Increment */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOper );
      /* duplicate a value */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_DUPLICATE );
      /* pop new value and leave the duplicated copy of it on the stack */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_POP_PCODE );
   }
}

/* Generates the pcodes for post- increment/decrement expressions
 */
#if defined( HB_MACRO_SUPPORT )
void hb_compExprPushPostOp( HB_EXPR_PTR pSelf, BYTE bOper, HB_MACRO_DECL )
#else
void hb_compExprPushPostOp( HB_EXPR_PTR pSelf, BYTE bOper )
#endif
{
   /* NOTE: an object instance variable needs special handling
    */
   if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
   {
      /* push current value - it will be a result of whole expression */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_PUSH_PCODE );
      /* now increment the value */
      HB_EXPR_PCODE2( hb_compExprPushPreOp, pSelf, bOper );
      /* pop the value from the stack */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_POP );
   }
   else
   {
      /* Push current value */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_PUSH_PCODE );
      /* Duplicate value */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_DUPLICATE );
      /* Increment */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOper );
      /* pop new value from the stack */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_POP_PCODE );
   }
}

/* Generates the pcodes for increment/decrement operations
 * used standalone as a statement
 */
#if defined( HB_MACRO_SUPPORT )
void hb_compExprUsePreOp( HB_EXPR_PTR pSelf, BYTE bOper, HB_MACRO_DECL )
#else
void hb_compExprUsePreOp( HB_EXPR_PTR pSelf, BYTE bOper )
#endif
{
   /* NOTE: an object instance variable needs special handling
    */
   if( pSelf->value.asOperator.pLeft->ExprType == HB_ET_SEND )
   {
      HB_EXPR_PCODE2( hb_compExprPushPreOp, pSelf, bOper );
      /* pop the value from the stack */
      HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_POP );
   }
   else
   {
      /* Push current value */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_PUSH_PCODE );
      /* Increment */
      HB_EXPR_PCODE1( hb_compGenPCode1, bOper );
      /* pop new value from the stack */
      HB_EXPR_USE( pSelf->value.asOperator.pLeft, HB_EA_POP_PCODE );
   }
}

/* Generate pcode for aliased expression which contains macro operator on
 * the left or right side of the alias operator
 * expression->&macro or &macro->expression or &macro->&macro
 */
#if defined( HB_MACRO_SUPPORT )
void hb_compExprUseAliasMacro( HB_EXPR_PTR pAliasedVar, BYTE bAction, HB_MACRO_DECL )
#else
void hb_compExprUseAliasMacro( HB_EXPR_PTR pAliasedVar, BYTE bAction )
#endif
{
   HB_EXPR_PTR pAlias, pVar;

   /* Alias->Var
    */
   pAlias = pAliasedVar->value.asAlias.pAlias;
   pVar   = pAliasedVar->value.asAlias.pVar;
   if( pAlias->ExprType == HB_ET_ALIAS )
   {
      /* database alias */
      /* Push alias identifier as string so it can be joined with
       * variable at runtime
       * NOTE:
       *    ALIAS->&var is the same as &( "ALIAS->" + var )
       *
       */
      HB_EXPR_PCODE2( hb_compGenPushString, pAlias->value.asSymbol, strlen(pAlias->value.asSymbol) );
      HB_EXPR_USE( pVar, HB_EA_PUSH_PCODE );
      if( bAction == HB_EA_PUSH_PCODE )
         HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_MACROPUSHALIASED );
      else
         HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_MACROPOPALIASED );
   }
   else if( pVar->ExprType == HB_ET_VARIABLE )
   {
      /* NOTE:
       *    &macro->var is the  same as: &( macro + "->var" )
       */
      HB_EXPR_USE( pAlias, HB_EA_PUSH_PCODE );
      HB_EXPR_PCODE2( hb_compGenPushString, pVar->value.asSymbol, strlen(pVar->value.asSymbol) );
      if( bAction == HB_EA_PUSH_PCODE )
         HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_MACROPUSHALIASED );
      else
         HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_MACROPOPALIASED );
   }
   else
   {
      HB_EXPR_USE( pAlias, HB_EA_PUSH_PCODE );
      HB_EXPR_USE( pVar, HB_EA_PUSH_PCODE );
      if( bAction == HB_EA_PUSH_PCODE )
         HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_MACROPUSHALIASED );
      else
         HB_EXPR_PCODE1( hb_compGenPCode1, HB_P_MACROPOPALIASED );
   }

}


/* Reduces the list of expressions
 *
 * pExpr is the first expression on the list
 */
#if defined( HB_MACRO_SUPPORT )
ULONG hb_compExprReduceList( HB_EXPR_PTR pExpr, HB_MACRO_DECL )
#else
ULONG hb_compExprReduceList( HB_EXPR_PTR pExpr )
#endif
{
   HB_EXPR_PTR pNext;
   HB_EXPR_PTR * pPrev;
   ULONG ulCnt = 0;

   /* NOTE: During optimalization an expression on the list can be
    * replaced by the new one
    */

   pPrev = &pExpr->value.asList.pExprList;
   pExpr = pExpr->value.asList.pExprList;
   while( pExpr )
   {
      pNext  = pExpr->pNext; /* store next expression in case the current  will be reduced */
      pExpr  = HB_EXPR_USE( pExpr, HB_EA_REDUCE );
      *pPrev = pExpr;   /* store a new expression into the previous one */
      pExpr->pNext = pNext;  /* restore the link to next expression */
      pPrev  = &pExpr->pNext;
      pExpr  = pNext;
      ++ulCnt;
   }
   return ulCnt;
}

BOOL hb_compExprCheckMacroVar( char * szText )
{
   char * pTmp = szText;
   BOOL bTextSubst = FALSE;

   while( ( pTmp = strchr( pTmp, '&' ) ) != NULL )
   {
      /* Check if macro operator is used inside a string
       * Macro operator is ignored if it is the last char or
       * next char is '(' e.g. "this is &(ignored)"
       *
       * NOTE: This uses _a-zA-Z pattern to check for
       * variable name beginning
       */

      ++pTmp;
      bTextSubst = ( *pTmp == '_' || (*pTmp >= 'A' && *pTmp <= 'Z') || (*pTmp >= 'a' && *pTmp <= 'z') );
      /* NOTE: All variables are assumed memvars in macro compiler -
       * there is no need to check for a valid name
       */
#if !defined( HB_MACRO_SUPPORT )
      if( bTextSubst )
      {
         /* There is a valid character after '&' that can be used in
          * variable name - check if the whole variable name is valid
          * (local, static and field  variable names are invalid because
          * they are not visible at runtime)
          */
         char * pStart = pTmp;
         char cSave;

         /* NOTE: This uses _a-zA-Z0-9 pattern to check for
          * variable name
          */
         while( *pTmp && (*pTmp == '_' || (*pTmp >= 'A' && *pTmp <= 'Z') || (*pTmp >= 'a' && *pTmp <= 'z') || (*pTmp >= '0' && *pTmp <= '9')) )
            ++pTmp;

         cSave = *pTmp;
         *pTmp = '\0';
         hb_compVariableMacroCheck( pStart );
         *pTmp = cSave;
      }
#endif
   }
   return bTextSubst;
}