cexp.c

gcc库的原代码,对编程有很大帮助.

case 23:
#line 303 "cexp.y"
{ yyval.integer.unsignedp = 0;
			  if (yyvsp[-2].integer.unsignedp || yyvsp[0].integer.unsignedp)
			    yyval.integer.value = (unsigned long) yyvsp[-2].integer.value < yyvsp[0].integer.value;
			  else
			    yyval.integer.value = yyvsp[-2].integer.value < yyvsp[0].integer.value; ;
    break;}
case 24:
#line 309 "cexp.y"
{ yyval.integer.unsignedp = 0;
			  if (yyvsp[-2].integer.unsignedp || yyvsp[0].integer.unsignedp)
			    yyval.integer.value = (unsigned long) yyvsp[-2].integer.value > yyvsp[0].integer.value;
			  else
			    yyval.integer.value = yyvsp[-2].integer.value > yyvsp[0].integer.value; ;
    break;}
case 25:
#line 315 "cexp.y"
{ yyval.integer.value = yyvsp[-2].integer.value & yyvsp[0].integer.value;
			  yyval.integer.unsignedp = yyvsp[-2].integer.unsignedp || yyvsp[0].integer.unsignedp; ;
    break;}
case 26:
#line 318 "cexp.y"
{ yyval.integer.value = yyvsp[-2].integer.value ^ yyvsp[0].integer.value;
			  yyval.integer.unsignedp = yyvsp[-2].integer.unsignedp || yyvsp[0].integer.unsignedp; ;
    break;}
case 27:
#line 321 "cexp.y"
{ yyval.integer.value = yyvsp[-2].integer.value | yyvsp[0].integer.value;
			  yyval.integer.unsignedp = yyvsp[-2].integer.unsignedp || yyvsp[0].integer.unsignedp; ;
    break;}
case 28:
#line 324 "cexp.y"
{ skip_evaluation += !yyvsp[-1].integer.value; ;
    break;}
case 29:
#line 326 "cexp.y"
{ skip_evaluation -= !yyvsp[-3].integer.value;
			  yyval.integer.value = (yyvsp[-3].integer.value && yyvsp[0].integer.value);
			  yyval.integer.unsignedp = 0; ;
    break;}
case 30:
#line 330 "cexp.y"
{ skip_evaluation += !!yyvsp[-1].integer.value; ;
    break;}
case 31:
#line 332 "cexp.y"
{ skip_evaluation -= !!yyvsp[-3].integer.value;
			  yyval.integer.value = (yyvsp[-3].integer.value || yyvsp[0].integer.value);
			  yyval.integer.unsignedp = 0; ;
    break;}
case 32:
#line 336 "cexp.y"
{ skip_evaluation += !yyvsp[-1].integer.value; ;
    break;}
case 33:
#line 338 "cexp.y"
{ skip_evaluation += !!yyvsp[-4].integer.value - !yyvsp[-4].integer.value; ;
    break;}
case 34:
#line 340 "cexp.y"
{ skip_evaluation -= !!yyvsp[-6].integer.value;
			  yyval.integer.value = yyvsp[-6].integer.value ? yyvsp[-3].integer.value : yyvsp[0].integer.value;
			  yyval.integer.unsignedp = yyvsp[-3].integer.unsignedp || yyvsp[0].integer.unsignedp; ;
    break;}
case 35:
#line 344 "cexp.y"
{ yyval.integer = yylval.integer; ;
    break;}
case 36:
#line 346 "cexp.y"
{ yyval.integer = yylval.integer; ;
    break;}
case 37:
#line 348 "cexp.y"
{ yyval.integer.value = 0;
			  yyval.integer.unsignedp = 0; ;
    break;}
case 38:
#line 353 "cexp.y"
{ yyval.keywords = 0; ;
    break;}
case 39:
#line 355 "cexp.y"
{ struct arglist *temp;
			  yyval.keywords = (struct arglist *) xmalloc (sizeof (struct arglist));
			  yyval.keywords->next = yyvsp[-2].keywords;
			  yyval.keywords->name = (U_CHAR *) "(";
			  yyval.keywords->length = 1;
			  temp = yyval.keywords;
			  while (temp != 0 && temp->next != 0)
			    temp = temp->next;
			  temp->next = (struct arglist *) xmalloc (sizeof (struct arglist));
			  temp->next->next = yyvsp[0].keywords;
			  temp->next->name = (U_CHAR *) ")";
			  temp->next->length = 1; ;
    break;}
case 40:
#line 368 "cexp.y"
{ yyval.keywords = (struct arglist *) xmalloc (sizeof (struct arglist));
			  yyval.keywords->name = yyvsp[-1].name.address;
			  yyval.keywords->length = yyvsp[-1].name.length;
			  yyval.keywords->next = yyvsp[0].keywords; ;
    break;}
}
   /* the action file gets copied in in place of this dollarsign */
#line 480 "/usr/local/lib/bison.simple"

  yyvsp -= yylen;
  yyssp -= yylen;
#ifdef YYLSP_NEEDED
  yylsp -= yylen;
#endif

#if YYDEBUG != 0
  if (yydebug)
    {
      short *ssp1 = yyss - 1;
      fprintf (stderr, "state stack now");
      while (ssp1 != yyssp)
	fprintf (stderr, " %d", *++ssp1);
      fprintf (stderr, "\n");
    }
#endif

  *++yyvsp = yyval;

#ifdef YYLSP_NEEDED
  yylsp++;
  if (yylen == 0)
    {
      yylsp->first_line = yylloc.first_line;
      yylsp->first_column = yylloc.first_column;
      yylsp->last_line = (yylsp-1)->last_line;
      yylsp->last_column = (yylsp-1)->last_column;
      yylsp->text = 0;
    }
  else
    {
      yylsp->last_line = (yylsp+yylen-1)->last_line;
      yylsp->last_column = (yylsp+yylen-1)->last_column;
    }
#endif

  /* Now "shift" the result of the reduction.
     Determine what state that goes to,
     based on the state we popped back to
     and the rule number reduced by.  */

  yyn = yyr1[yyn];

  yystate = yypgoto[yyn - YYNTBASE] + *yyssp;
  if (yystate >= 0 && yystate <= YYLAST && yycheck[yystate] == *yyssp)
    yystate = yytable[yystate];
  else
    yystate = yydefgoto[yyn - YYNTBASE];

  goto yynewstate;

yyerrlab:   /* here on detecting error */

  if (! yyerrstatus)
    /* If not already recovering from an error, report this error.  */
    {
      ++yynerrs;

#ifdef YYERROR_VERBOSE
      yyn = yypact[yystate];

      if (yyn > YYFLAG && yyn < YYLAST)
	{
	  int size = 0;
	  char *msg;
	  int x, count;

	  count = 0;
	  /* Start X at -yyn if nec to avoid negative indexes in yycheck.  */
	  for (x = (yyn < 0 ? -yyn : 0);
	       x < (sizeof(yytname) / sizeof(char *)); x++)
	    if (yycheck[x + yyn] == x)
	      size += strlen(yytname[x]) + 15, count++;
	  msg = (char *) malloc(size + 15);
	  if (msg != 0)
	    {
	      strcpy(msg, "parse error");

	      if (count < 5)
		{
		  count = 0;
		  for (x = (yyn < 0 ? -yyn : 0);
		       x < (sizeof(yytname) / sizeof(char *)); x++)
		    if (yycheck[x + yyn] == x)
		      {
			strcat(msg, count == 0 ? ", expecting `" : " or `");
			strcat(msg, yytname[x]);
			strcat(msg, "'");
			count++;
		      }
		}
	      yyerror(msg);
	      free(msg);
	    }
	  else
	    yyerror ("parse error; also virtual memory exceeded");
	}
      else
#endif /* YYERROR_VERBOSE */
	yyerror("parse error");
    }

  goto yyerrlab1;
yyerrlab1:   /* here on error raised explicitly by an action */

  if (yyerrstatus == 3)
    {
      /* if just tried and failed to reuse lookahead token after an error, discard it.  */

      /* return failure if at end of input */
      if (yychar == YYEOF)
	YYABORT;

#if YYDEBUG != 0
      if (yydebug)
	fprintf(stderr, "Discarding token %d (%s).\n", yychar, yytname[yychar1]);
#endif

      yychar = YYEMPTY;
    }

  /* Else will try to reuse lookahead token
     after shifting the error token.  */

  yyerrstatus = 3;		/* Each real token shifted decrements this */

  goto yyerrhandle;

yyerrdefault:  /* current state does not do anything special for the error token. */

#if 0
  /* This is wrong; only states that explicitly want error tokens
     should shift them.  */
  yyn = yydefact[yystate];  /* If its default is to accept any token, ok.  Otherwise pop it.*/
  if (yyn) goto yydefault;
#endif

yyerrpop:   /* pop the current state because it cannot handle the error token */

  if (yyssp == yyss) YYABORT;
  yyvsp--;
  yystate = *--yyssp;
#ifdef YYLSP_NEEDED
  yylsp--;
#endif

#if YYDEBUG != 0
  if (yydebug)
    {
      short *ssp1 = yyss - 1;
      fprintf (stderr, "Error: state stack now");
      while (ssp1 != yyssp)
	fprintf (stderr, " %d", *++ssp1);
      fprintf (stderr, "\n");
    }
#endif

yyerrhandle:

  yyn = yypact[yystate];
  if (yyn == YYFLAG)
    goto yyerrdefault;

  yyn += YYTERROR;
  if (yyn < 0 || yyn > YYLAST || yycheck[yyn] != YYTERROR)
    goto yyerrdefault;

  yyn = yytable[yyn];
  if (yyn < 0)
    {
      if (yyn == YYFLAG)
	goto yyerrpop;
      yyn = -yyn;
      goto yyreduce;
    }
  else if (yyn == 0)
    goto yyerrpop;

  if (yyn == YYFINAL)
    YYACCEPT;

#if YYDEBUG != 0
  if (yydebug)
    fprintf(stderr, "Shifting error token, ");
#endif

  *++yyvsp = yylval;
#ifdef YYLSP_NEEDED
  *++yylsp = yylloc;
#endif

  yystate = yyn;
  goto yynewstate;
}
#line 373 "cexp.y"


/* During parsing of a C expression, the pointer to the next character
   is in this variable.  */

static char *lexptr;

/* Take care of parsing a number (anything that starts with a digit).
   Set yylval and return the token type; update lexptr.
   LEN is the number of characters in it.  */

/* maybe needs to actually deal with floating point numbers */

int
parse_number (olen)
     int olen;
{
  register char *p = lexptr;
  register int c;
  register unsigned long n = 0, nd, ULONG_MAX_over_base;
  register int base = 10;
  register int len = olen;
  register int overflow = 0;
  register int digit, largest_digit = 0;
  int spec_long = 0;

  for (c = 0; c < len; c++)
    if (p[c] == '.') {
      /* It's a float since it contains a point.  */
      yyerror ("floating point numbers not allowed in #if expressions");
      return ERROR;
    }

  yylval.integer.unsignedp = 0;

  if (len >= 3 && (!strncmp (p, "0x", 2) || !strncmp (p, "0X", 2))) {
    p += 2;
    base = 16;
    len -= 2;
  }
  else if (*p == '0')
    base = 8;

  ULONG_MAX_over_base = (unsigned long) -1 / base;

  for (; len > 0; len--) {
    c = *p++;

    if (c >= '0' && c <= '9')
      digit = c - '0';
    else if (base == 16 && c >= 'a' && c <= 'f')
      digit = c - 'a' + 10;
    else if (base == 16 && c >= 'A' && c <= 'F')
      digit = c - 'A' + 10;
    else {
      /* `l' means long, and `u' means unsigned.  */
      while (1) {
	if (c == 'l' || c == 'L')
	  {
	    if (spec_long)
	      yyerror ("two `l's in integer constant");
	    spec_long = 1;
	  }
	else if (c == 'u' || c == 'U')
	  {
	    if (yylval.integer.unsignedp)
	      yyerror ("two `u's in integer constant");
	    yylval.integer.unsignedp = 1;
	  }
	else
	  break;

	if (--len == 0)
	  break;
	c = *p++;
      }
      /* Don't look for any more digits after the suffixes.  */
      break;
    }
    if (largest_digit < digit)
      largest_digit = digit;
    nd = n * base + digit;
    overflow |= ULONG_MAX_over_base < n | nd < n;
    n = nd;
  }

  if (len != 0) {
    yyerror ("Invalid number in #if expression");
    return ERROR;
  }

  if (base <= largest_digit)
    warning ("integer constant contains digits beyond the radix");

  if (overflow)
    warning ("integer constant out of range");

  /* If too big to be signed, consider it unsigned.  */
  if ((long) n < 0 && ! yylval.integer.unsignedp)
    {
      if (base == 10)
	warning ("integer constant is so large that it is unsigned");
      yylval.integer.unsignedp = 1;
    }

  lexptr = p;
  yylval.integer.value = n;
  return INT;
}

struct token {
  char *operator;
  int token;
};

static struct token tokentab2[] = {
  {"&&", AND},
  {"||", OR},
  {"<<", LSH},
  {">>", RSH},
  {"==", EQUAL},
  {"!=", NOTEQUAL},
  {"<=", LEQ},
  {">=", GEQ},
  {"++", ERROR},
  {"--", ERROR},
  {NULL, ERROR}
};

/* Read one token, getting characters through lexptr.  */

int
yylex ()
{
  register int c;
  register int namelen;
  register unsigned char *tokstart;
  register struct token *toktab;
  int wide_flag;

 retry:

  tokstart = (unsigned char *) lexptr;
  c = *tokstart;
  /* See if it is a special token of length 2.  */
  if (! keyword_parsing)
    for (toktab = tokentab2; toktab->operator != NULL; toktab++)
      if (c == *toktab->operator && tokstart[1] == toktab->operator[1]) {
	lexptr += 2;
	if (toktab->token == ERROR)
	  {
	    char *buf = (char *) alloca (40);
	    sprintf (buf, "`%s' not allowed in operand of `#if'", toktab->operator);
	    yyerror (buf);
	  }
	return toktab->token;
      }

  switch (c) {
  case 0:
    return 0;
    
  case ' ':
  case '\t':
  case '\r':
  case '\n':
    lexptr++;
    goto retry;
    
  case 'L':
    /* Capital L may start a wide-string or wide-character constant.  */
    if (lexptr[1] == '\'')
      {
	lexptr++;
	wide_flag = 1;
	goto char_constant;
      }
    if (lexptr[1] == '"')
      {
	lexptr++;
	wide_flag = 1;
	goto string_constant;
      }
    break;

  case '\'':
    wide_flag = 0;