example2.cpp

学习lemon语法分析的windows程序

#endif
      return yy_find_shift_action(pParser, iFallback);
    }
#endif
    return yy_default[stateno];
  }else{
    return yy_action[i];
  }
}

/*
** Find the appropriate action for a parser given the non-terminal
** look-ahead token iLookAhead.
**
** If the look-ahead token is YYNOCODE, then check to see if the action is
** independent of the look-ahead.  If it is, return the action, otherwise
** return YY_NO_ACTION.
*/
static int yy_find_reduce_action(
  yyParser *pParser,        /* The parser */
  int iLookAhead            /* The look-ahead token */
){
  int i;
  int stateno = pParser->yystack[pParser->yyidx].stateno;
 
  i = yy_reduce_ofst[stateno];
  if( i==YY_REDUCE_USE_DFLT ){
    return yy_default[stateno];
  }
  if( iLookAhead==YYNOCODE ){
    return YY_NO_ACTION;
  }
  i += iLookAhead;
  if( i<0 || i>=YY_SZ_ACTTAB || yy_lookahead[i]!=iLookAhead ){
    return yy_default[stateno];
  }else{
    return yy_action[i];
  }
}

/*
** Perform a shift action.
*/
static void yy_shift(
  yyParser *yypParser,          /* The parser to be shifted */
  int yyNewState,               /* The new state to shift in */
  int yyMajor,                  /* The major token to shift in */
  YYMINORTYPE *yypMinor         /* Pointer ot the minor token to shift in */
){
  yyStackEntry *yytos;
  yypParser->yyidx++;
  if( yypParser->yyidx>=YYSTACKDEPTH ){
     ParseARG_FETCH;
     yypParser->yyidx--;
#ifndef NDEBUG
     if( yyTraceFILE ){
       fprintf(yyTraceFILE,"%sStack Overflow!\n",yyTracePrompt);
     }
#endif
     while( yypParser->yyidx>=0 ) yy_pop_parser_stack(yypParser);
     /* Here code is inserted which will execute if the parser
     ** stack every overflows */
     ParseARG_STORE; /* Suppress warning about unused %extra_argument var */
     return;
  }
  yytos = &yypParser->yystack[yypParser->yyidx];
  yytos->stateno = yyNewState;
  yytos->major = yyMajor;
  yytos->minor = *yypMinor;
#ifndef NDEBUG
  if( yyTraceFILE && yypParser->yyidx>0 ){
    int i;
    fprintf(yyTraceFILE,"%sShift %d\n",yyTracePrompt,yyNewState);
    fprintf(yyTraceFILE,"%sStack:",yyTracePrompt);
    for(i=1; i<=yypParser->yyidx; i++)
      fprintf(yyTraceFILE," %s",yyTokenName[yypParser->yystack[i].major]);
    fprintf(yyTraceFILE,"\n");
  }
#endif
}

/* The following table contains information about every rule that
** is used during the reduce.
*/
static struct {
  YYCODETYPE lhs;         /* Symbol on the left-hand side of the rule */
  unsigned char nrhs;     /* Number of right-hand side symbols in the rule */
} yyRuleInfo[] = {
  { 8, 1 },
  { 7, 3 },
  { 7, 3 },
  { 7, 3 },
  { 7, 3 },
  { 7, 1 },
};

static void yy_accept(yyParser*);  /* Forward Declaration */

/*
** Perform a reduce action and the shift that must immediately
** follow the reduce.
*/
static void yy_reduce(
  yyParser *yypParser,         /* The parser */
  int yyruleno                 /* Number of the rule by which to reduce */
){
  int yygoto;                     /* The next state */
  int yyact;                      /* The next action */
  YYMINORTYPE yygotominor;        /* The LHS of the rule reduced */
  yyStackEntry *yymsp;            /* The top of the parser's stack */
  int yysize;                     /* Amount to pop the stack */
  ParseARG_FETCH;
  yymsp = &yypParser->yystack[yypParser->yyidx];
#ifndef NDEBUG
  if( yyTraceFILE && yyruleno>=0 
        && yyruleno<sizeof(yyRuleName)/sizeof(yyRuleName[0]) ){
    fprintf(yyTraceFILE, "%sReduce [%s].\n", yyTracePrompt,
      yyRuleName[yyruleno]);
  }
#endif /* NDEBUG */

  switch( yyruleno ){
  /* Beginning here are the reduction cases.  A typical example
  ** follows:
  **   case 0:
  **  #line <lineno> <grammarfile>
  **     { ... }           // User supplied code
  **  #line <lineno> <thisfile>
  **     break;
  */
      case 0:
#line 78 "example2.y"
{ 
                        std::cout << "Result.value=" << yymsp[0].minor.yy18.value << std::endl; 
                        std::cout << "Result.n=" << yymsp[0].minor.yy18.n << std::endl; 

                         }
#line 534 "example2.c"
        break;
      case 1:
#line 85 "example2.y"
{ yygotominor.yy18.value = yymsp[-2].minor.yy18.value - yymsp[0].minor.yy18.value; 
                                       yygotominor.yy18.n = yymsp[-2].minor.yy18.n+1  + yymsp[0].minor.yy18.n+1;
                                      }
#line 541 "example2.c"
        break;
      case 2:
#line 89 "example2.y"
{ yygotominor.yy18.value = yymsp[-2].minor.yy18.value + yymsp[0].minor.yy18.value; 
                                       yygotominor.yy18.n = yymsp[-2].minor.yy18.n+1  + yymsp[0].minor.yy18.n+1;
                                      }
#line 548 "example2.c"
        break;
      case 3:
#line 93 "example2.y"
{ yygotominor.yy18.value = yymsp[-2].minor.yy18.value * yymsp[0].minor.yy18.value;
                                        yygotominor.yy18.n = yymsp[-2].minor.yy18.n+1  + yymsp[0].minor.yy18.n+1;

                                         }
#line 556 "example2.c"
        break;
      case 4:
#line 97 "example2.y"
{ 

         if(yymsp[0].minor.yy18.value != 0){
           yygotominor.yy18.value = yymsp[-2].minor.yy18.value / yymsp[0].minor.yy18.value;
           yygotominor.yy18.n = yymsp[-2].minor.yy18.n+1 + yymsp[0].minor.yy18.n+1;
          }else{
           std::cout << "divide by zero" << std::endl;
           }
}
#line 569 "example2.c"
        break;
      case 5:
#line 106 "example2.y"
{ yygotominor.yy18.value = yymsp[0].minor.yy0.value; yygotominor.yy18.n = yymsp[0].minor.yy0.n+1; }
#line 574 "example2.c"
        break;
  };
  yygoto = yyRuleInfo[yyruleno].lhs;
  yysize = yyRuleInfo[yyruleno].nrhs;
  yypParser->yyidx -= yysize;
  yyact = yy_find_reduce_action(yypParser,yygoto);
  if( yyact < YYNSTATE ){
    yy_shift(yypParser,yyact,yygoto,&yygotominor);
  }else if( yyact == YYNSTATE + YYNRULE + 1 ){
    yy_accept(yypParser);
  }
}

/*
** The following code executes when the parse fails
*/
static void yy_parse_failed(
  yyParser *yypParser           /* The parser */
){
  ParseARG_FETCH;
#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sFail!\n",yyTracePrompt);
  }
#endif
  while( yypParser->yyidx>=0 ) yy_pop_parser_stack(yypParser);
  /* Here code is inserted which will be executed whenever the
  ** parser fails */
  ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
}

/*
** The following code executes when a syntax error first occurs.
*/
static void yy_syntax_error(
  yyParser *yypParser,           /* The parser */
  int yymajor,                   /* The major type of the error token */
  YYMINORTYPE yyminor            /* The minor type of the error token */
){
  ParseARG_FETCH;
#define TOKEN (yyminor.yy0)
#line 74 "example2.y"
  
  std::cout << "Syntax error!" << std::endl;  

#line 620 "example2.c"
  ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
}

/*
** The following is executed when the parser accepts
*/
static void yy_accept(
  yyParser *yypParser           /* The parser */
){
  ParseARG_FETCH;
#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sAccept!\n",yyTracePrompt);
  }
#endif
  while( yypParser->yyidx>=0 ) yy_pop_parser_stack(yypParser);
  /* Here code is inserted which will be executed whenever the
  ** parser accepts */
  ParseARG_STORE; /* Suppress warning about unused %extra_argument variable */
}

/* The main parser program.
** The first argument is a pointer to a structure obtained from
** "ParseAlloc" which describes the current state of the parser.
** The second argument is the major token number.  The third is
** the minor token.  The fourth optional argument is whatever the
** user wants (and specified in the grammar) and is available for
** use by the action routines.
**
** Inputs:
** <ul>
** <li> A pointer to the parser (an opaque structure.)
** <li> The major token number.
** <li> The minor token number.
** <li> An option argument of a grammar-specified type.
** </ul>
**
** Outputs:
** None.
*/
void Parse(
  void *yyp,                   /* The parser */
  int yymajor,                 /* The major token code number */
  ParseTOKENTYPE yyminor       /* The value for the token */
  ParseARG_PDECL               /* Optional %extra_argument parameter */
){
  YYMINORTYPE yyminorunion;
  int yyact;            /* The parser action. */
  int yyendofinput;     /* True if we are at the end of input */
  int yyerrorhit = 0;   /* True if yymajor has invoked an error */
  yyParser *yypParser;  /* The parser */

  /* (re)initialize the parser, if necessary */
  yypParser = (yyParser*)yyp;
  if( yypParser->yyidx<0 ){
    if( yymajor==0 ) return;
    yypParser->yyidx = 0;
    yypParser->yyerrcnt = -1;
    yypParser->yystack[0].stateno = 0;
    yypParser->yystack[0].major = 0;
  }
  yyminorunion.yy0 = yyminor;
  yyendofinput = (yymajor==0);
  ParseARG_STORE;

#ifndef NDEBUG
  if( yyTraceFILE ){
    fprintf(yyTraceFILE,"%sInput %s\n",yyTracePrompt,yyTokenName[yymajor]);
  }
#endif

  do{
    yyact = yy_find_shift_action(yypParser,yymajor);
    if( yyact<YYNSTATE ){
      yy_shift(yypParser,yyact,yymajor,&yyminorunion);
      yypParser->yyerrcnt--;
      if( yyendofinput && yypParser->yyidx>=0 ){
        yymajor = 0;
      }else{
        yymajor = YYNOCODE;
      }
    }else if( yyact < YYNSTATE + YYNRULE ){
      yy_reduce(yypParser,yyact-YYNSTATE);
    }else if( yyact == YY_ERROR_ACTION ){
      int yymx;
#ifndef NDEBUG
      if( yyTraceFILE ){
        fprintf(yyTraceFILE,"%sSyntax Error!\n",yyTracePrompt);
      }
#endif
#ifdef YYERRORSYMBOL
      /* A syntax error has occurred.
      ** The response to an error depends upon whether or not the
      ** grammar defines an error token "ERROR".  
      **
      ** This is what we do if the grammar does define ERROR:
      **
      **  * Call the %syntax_error function.
      **
      **  * Begin popping the stack until we enter a state where
      **    it is legal to shift the error symbol, then shift
      **    the error symbol.
      **
      **  * Set the error count to three.
      **
      **  * Begin accepting and shifting new tokens.  No new error
      **    processing will occur until three tokens have been
      **    shifted successfully.
      **
      */
      if( yypParser->yyerrcnt<0 ){
        yy_syntax_error(yypParser,yymajor,yyminorunion);
      }
      yymx = yypParser->yystack[yypParser->yyidx].major;
      if( yymx==YYERRORSYMBOL || yyerrorhit ){
#ifndef NDEBUG
        if( yyTraceFILE ){
          fprintf(yyTraceFILE,"%sDiscard input token %s\n",
             yyTracePrompt,yyTokenName[yymajor]);
        }
#endif
        yy_destructor(yymajor,&yyminorunion);
        yymajor = YYNOCODE;
      }else{
         while(
          yypParser->yyidx >= 0 &&
          yymx != YYERRORSYMBOL &&
          (yyact = yy_find_shift_action(yypParser,YYERRORSYMBOL)) >= YYNSTATE
        ){
          yy_pop_parser_stack(yypParser);
        }
        if( yypParser->yyidx < 0 || yymajor==0 ){
          yy_destructor(yymajor,&yyminorunion);
          yy_parse_failed(yypParser);
          yymajor = YYNOCODE;
        }else if( yymx!=YYERRORSYMBOL ){
          YYMINORTYPE u2;
          u2.YYERRSYMDT = 0;
          yy_shift(yypParser,yyact,YYERRORSYMBOL,&u2);
        }
      }
      yypParser->yyerrcnt = 3;
      yyerrorhit = 1;
#else  /* YYERRORSYMBOL is not defined */
      /* This is what we do if the grammar does not define ERROR:
      **
      **  * Report an error message, and throw away the input token.
      **
      **  * If the input token is $, then fail the parse.
      **
      ** As before, subsequent error messages are suppressed until
      ** three input tokens have been successfully shifted.
      */
      if( yypParser->yyerrcnt<=0 ){
        yy_syntax_error(yypParser,yymajor,yyminorunion);
      }
      yypParser->yyerrcnt = 3;
      yy_destructor(yymajor,&yyminorunion);
      if( yyendofinput ){
        yy_parse_failed(yypParser);
      }
      yymajor = YYNOCODE;
#endif
    }else{
      yy_accept(yypParser);
      yymajor = YYNOCODE;
    }
  }while( yymajor!=YYNOCODE && yypParser->yyidx>=0 );
  return;
}