gcc/tradcif.y

   1 /* Parse C expressions for CCCP.
   2    Copyright (C) 1987, 2000, 2001 Free Software Foundation.
   3    Adapted from expread.y of GDB by Paul Rubin, July 1986.
   4    Adapted to ANSI C, Richard Stallman, Jan 1987
   5    Dusted off, polished, and adapted for use as traditional
   6    preprocessor only, Zack Weinberg, Jul 2000
   7
   8 This program is free software; you can redistribute it and/or modify it
   9 under the terms of the GNU General Public License as published by the
  10 Free Software Foundation; either version 2, or (at your option) any
  11 later version.
  12
  13 This program is distributed in the hope that it will be useful,
  14 but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 GNU General Public License for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with this program; if not, write to the Free Software
  20 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  21
  22 /* Parse a C expression from text in a string  */
  23
  24 %{
  25 #include "config.h"
  26 #include "system.h"
  27 #include "intl.h"
  28 #include "tradcpp.h"
  29 #include <setjmp.h>
  30
  31   static int yylex PARAMS ((void));
  32   static void yyerror PARAMS ((const char *msgid)) ATTRIBUTE_NORETURN;
  33
  34   static int parse_number PARAMS ((int));
  35   static int parse_escape PARAMS ((const char **));
  36
  37   static int expression_value;
  38   static jmp_buf parse_return_error;
  39
  40   /* During parsing of a C expression, the pointer to the next
  41      character is in this variable.  */
  42
  43   static const char *lexptr;
  44 %}
  45
  46 %union {
  47   struct constant {long value; int unsignedp;} integer;
  48   int voidval;
  49   char *sval;
  50 }
  51
  52 %type <integer> exp exp1 start
  53 %token <integer> INT CHAR
  54 %token <sval> NAME
  55 %token <integer> ERROR
  56
  57 %right '?' ':'
  58 %left ','
  59 %left OR
  60 %left AND
  61 %left '|'
  62 %left '^'
  63 %left '&'
  64 %left EQUAL NOTEQUAL
  65 %left '<' '>' LEQ GEQ
  66 %left LSH RSH
  67 %left '+' '-'
  68 %left '*' '/' '%'
  69 %right UNARY
  70
  71 /* %expect 40 */
  72 \f
  73 %%
  74
  75 start   :       exp1
  76                 { expression_value = $1.value; }
  77         ;
  78
  79 /* Expressions, including the comma operator.  */
  80 exp1    :       exp
  81         |       exp1 ',' exp
  82                         { $$ = $3; }
  83         ;
  84
  85 /* Expressions, not including the comma operator.  */
  86 exp     :       '-' exp    %prec UNARY
  87                         { $$.value = - $2.value;
  88                           $$.unsignedp = $2.unsignedp; }
  89         |       '!' exp    %prec UNARY
  90                         { $$.value = ! $2.value;
  91                           $$.unsignedp = 0; }
  92         |       '+' exp    %prec UNARY
  93                         { $$ = $2; }
  94         |       '~' exp    %prec UNARY
  95                         { $$.value = ~ $2.value;
  96                           $$.unsignedp = $2.unsignedp; }
  97         |       '(' exp1 ')'
  98                         { $$ = $2; }
  99         ;
 100
 101 /* Binary operators in order of decreasing precedence.  */
 102 exp     :       exp '*' exp
 103                         { $$.unsignedp = $1.unsignedp || $3.unsignedp;
 104                           if ($$.unsignedp)
 105                             $$.value = (unsigned) $1.value * $3.value;
 106                           else
 107                             $$.value = $1.value * $3.value; }
 108         |       exp '/' exp
 109                         { if ($3.value == 0)
 110                             {
 111                               error ("division by zero in #if");
 112                               $3.value = 1;
 113                             }
 114                           $$.unsignedp = $1.unsignedp || $3.unsignedp;
 115                           if ($$.unsignedp)
 116                             $$.value = (unsigned) $1.value / $3.value;
 117                           else
 118                             $$.value = $1.value / $3.value; }
 119         |       exp '%' exp
 120                         { if ($3.value == 0)
 121                             {
 122                               error ("division by zero in #if");
 123                               $3.value = 1;
 124                             }
 125                           $$.unsignedp = $1.unsignedp || $3.unsignedp;
 126                           if ($$.unsignedp)
 127                             $$.value = (unsigned) $1.value % $3.value;
 128                           else
 129                             $$.value = $1.value % $3.value; }
 130         |       exp '+' exp
 131                         { $$.value = $1.value + $3.value;
 132                           $$.unsignedp = $1.unsignedp || $3.unsignedp; }
 133         |       exp '-' exp
 134                         { $$.value = $1.value - $3.value;
 135                           $$.unsignedp = $1.unsignedp || $3.unsignedp; }
 136         |       exp LSH exp
 137                         { $$.unsignedp = $1.unsignedp;
 138                           if ($$.unsignedp)
 139                             $$.value = (unsigned) $1.value << $3.value;
 140                           else
 141                             $$.value = $1.value << $3.value; }
 142         |       exp RSH exp
 143                         { $$.unsignedp = $1.unsignedp;
 144                           if ($$.unsignedp)
 145                             $$.value = (unsigned) $1.value >> $3.value;
 146                           else
 147                             $$.value = $1.value >> $3.value; }
 148         |       exp EQUAL exp
 149                         { $$.value = ($1.value == $3.value);
 150                           $$.unsignedp = 0; }
 151         |       exp NOTEQUAL exp
 152                         { $$.value = ($1.value != $3.value);
 153                           $$.unsignedp = 0; }
 154         |       exp LEQ exp
 155                         { $$.unsignedp = 0;
 156                           if ($1.unsignedp || $3.unsignedp)
 157                             $$.value =
 158                               (unsigned) $1.value <= (unsigned) $3.value;
 159                           else
 160                             $$.value = $1.value <= $3.value; }
 161         |       exp GEQ exp
 162                         { $$.unsignedp = 0;
 163                           if ($1.unsignedp || $3.unsignedp)
 164                             $$.value =
 165                               (unsigned) $1.value >= (unsigned) $3.value;
 166                           else
 167                             $$.value = $1.value >= $3.value; }
 168         |       exp '<' exp
 169                         { $$.unsignedp = 0;
 170                           if ($1.unsignedp || $3.unsignedp)
 171                             $$.value =
 172                               (unsigned) $1.value < (unsigned) $3.value;
 173                           else
 174                             $$.value = $1.value < $3.value; }
 175         |       exp '>' exp
 176                         { $$.unsignedp = 0;
 177                           if ($1.unsignedp || $3.unsignedp)
 178                             $$.value =
 179                               (unsigned) $1.value > (unsigned) $3.value;
 180                           else
 181                             $$.value = $1.value > $3.value; }
 182         |       exp '&' exp
 183                         { $$.value = $1.value & $3.value;
 184                           $$.unsignedp = $1.unsignedp || $3.unsignedp; }
 185         |       exp '^' exp
 186                         { $$.value = $1.value ^ $3.value;
 187                           $$.unsignedp = $1.unsignedp || $3.unsignedp; }
 188         |       exp '|' exp
 189                         { $$.value = $1.value | $3.value;
 190                           $$.unsignedp = $1.unsignedp || $3.unsignedp; }
 191         |       exp AND exp
 192                         { $$.value = ($1.value && $3.value);
 193                           $$.unsignedp = 0; }
 194         |       exp OR exp
 195                         { $$.value = ($1.value || $3.value);
 196                           $$.unsignedp = 0; }
 197         |       exp '?' exp ':' exp
 198                         { $$.value = $1.value ? $3.value : $5.value;
 199                           $$.unsignedp = $3.unsignedp || $5.unsignedp; }
 200         |       INT
 201                         { $$ = yylval.integer; }
 202         |       CHAR
 203                         { $$ = yylval.integer; }
 204         |       NAME
 205                         { $$.value = 0;
 206                           $$.unsignedp = 0; }
 207         |       '#'     { $$.value =
 208                             test_assertion ((unsigned char **) &lexptr); }
 209         ;
 210 %%
 211 \f
 212 /* Take care of parsing a number (anything that starts with a digit).
 213    Set yylval and return the token type; update lexptr.
 214    LEN is the number of characters in it.  */
 215
 216 /* maybe needs to actually deal with floating point numbers */
 217
 218 static int
 219 parse_number (olen)
 220      int olen;
 221 {
 222   const char *p = lexptr;
 223   long n = 0;
 224   int c;
 225   int base = 10;
 226   int len = olen;
 227
 228   for (c = 0; c < len; c++)
 229     if (p[c] == '.') {
 230       /* It's a float since it contains a point.  */
 231       yyerror ("floating point numbers not allowed in #if expressions");
 232       return ERROR;
 233     }
 234
 235   /* Traditionally, all numbers are signed.  However, we make it
 236      unsigned if requested with a suffix.  */
 237   yylval.integer.unsignedp = 0;
 238
 239   if (len >= 3 && (!strncmp (p, "0x", 2) || !strncmp (p, "0X", 2))) {
 240     p += 2;
 241     base = 16;
 242     len -= 2;
 243   }
 244   else if (*p == '0')
 245     base = 8;
 246
 247   while (len > 0) {
 248     c = *p++;
 249     len--;
 250     if (ISUPPER (c))
 251       c = TOLOWER (c);
 252
 253     if (ISDIGIT (c)
 254         || (base == 16 && ISXDIGIT (c))) {
 255       n = (n * base) + hex_value (c);
 256     } else {
 257       /* `l' means long, and `u' means unsigned.  */
 258       while (1) {
 259         if (c == 'l' || c == 'L')
 260           ;
 261         else if (c == 'u' || c == 'U')
 262           yylval.integer.unsignedp = 1;
 263         else
 264           break;
 265
 266         if (len == 0)
 267           break;
 268         c = *p++;
 269         len--;
 270       }
 271       /* Don't look for any more digits after the suffixes.  */
 272       break;
 273     }
 274   }
 275
 276   if (len != 0) {
 277     yyerror ("invalid number in #if expression");
 278     return ERROR;
 279   }
 280
 281   lexptr = p;
 282   yylval.integer.value = n;
 283   return INT;
 284 }
 285
 286 struct token {
 287   const char *const operator;
 288   const int token;
 289 };
 290
 291 #ifndef NULL
 292 #define NULL 0
 293 #endif
 294
 295 static const struct token tokentab2[] = {
 296   {"&&", AND},
 297   {"||", OR},
 298   {"<<", LSH},
 299   {">>", RSH},
 300   {"==", EQUAL},
 301   {"!=", NOTEQUAL},
 302   {"<=", LEQ},
 303   {">=", GEQ},
 304   {NULL, ERROR}
 305 };
 306
 307 /* Read one token, getting characters through lexptr.  */
 308
 309 static int
 310 yylex ()
 311 {
 312   int c;
 313   int namelen;
 314   const char *tokstart;
 315   const struct token *toktab;
 316
 317  retry:
 318
 319   tokstart = lexptr;
 320   c = *tokstart;
 321   /* See if it is a special token of length 2.  */
 322   for (toktab = tokentab2; toktab->operator != NULL; toktab++)
 323     if (c == *toktab->operator && tokstart[1] == toktab->operator[1]) {
 324       lexptr += 2;
 325       return toktab->token;
 326     }
 327
 328   switch (c) {
 329   case 0:
 330     return 0;
 331
 332   case ' ':
 333   case '\t':
 334   case '\r':
 335   case '\n':
 336     lexptr++;
 337     goto retry;
 338
 339   case '\'':
 340     lexptr++;
 341     c = *lexptr++;
 342     if (c == '\\')
 343       c = parse_escape (&lexptr);
 344
 345     /* Sign-extend the constant if chars are signed on target machine.  */
 346     {
 347       if (lookup ((const unsigned char *)"__CHAR_UNSIGNED__",
 348                    sizeof ("__CHAR_UNSIGNED__")-1, -1)
 349           || ((c >> (CHAR_TYPE_SIZE - 1)) & 1) == 0)
 350         yylval.integer.value = c & ((1 << CHAR_TYPE_SIZE) - 1);
 351       else
 352         yylval.integer.value = c | ~((1 << CHAR_TYPE_SIZE) - 1);
 353     }
 354
 355     yylval.integer.unsignedp = 0;
 356     c = *lexptr++;
 357     if (c != '\'') {
 358       yyerror ("invalid character constant in #if");
 359       return ERROR;
 360     }
 361
 362     return CHAR;
 363
 364     /* some of these chars are invalid in constant expressions;
 365        maybe do something about them later */
 366   case '/':
 367   case '+':
 368   case '-':
 369   case '*':
 370   case '%':
 371   case '|':
 372   case '&':
 373   case '^':
 374   case '~':
 375   case '!':
 376   case '@':
 377   case '<':
 378   case '>':
 379   case '(':
 380   case ')':
 381   case '[':
 382   case ']':
 383   case '.':
 384   case '?':
 385   case ':':
 386   case '=':
 387   case '{':
 388   case '}':
 389   case ',':
 390   case '#':
 391     lexptr++;
 392     return c;
 393
 394   case '"':
 395     yyerror ("double quoted strings not allowed in #if expressions");
 396     return ERROR;
 397   }
 398   if (ISDIGIT (c)) {
 399     /* It's a number */
 400     for (namelen = 0;
 401          c = tokstart[namelen], is_idchar (c) || c == '.';
 402          namelen++)
 403       ;
 404     return parse_number (namelen);
 405   }
 406
 407   if (!is_idstart (c)) {
 408     yyerror ("invalid token in expression");
 409     return ERROR;
 410   }
 411
 412   /* It is a name.  See how long it is.  */
 413
 414   for (namelen = 0;
 415        is_idchar (tokstart[namelen]);
 416        namelen++)
 417     ;
 418
 419   lexptr += namelen;
 420   return NAME;
 421 }
 422
 423
 424 /* Parse a C escape sequence.  STRING_PTR points to a variable
 425    containing a pointer to the string to parse.  That pointer
 426    is updated past the characters we use.  The value of the
 427    escape sequence is returned.
 428
 429    A negative value means the sequence \ newline was seen,
 430    which is supposed to be equivalent to nothing at all.
 431
 432    If \ is followed by a null character, we return a negative
 433    value and leave the string pointer pointing at the null character.
 434
 435    If \ is followed by 000, we return 0 and leave the string pointer
 436    after the zeros.  A value of 0 does not mean end of string.  */
 437
 438 static int
 439 parse_escape (string_ptr)
 440      const char **string_ptr;
 441 {
 442   int c = *(*string_ptr)++;
 443   switch (c)
 444     {
 445     case 'a':
 446       return TARGET_BELL;
 447     case 'b':
 448       return TARGET_BS;
 449     case 'e':
 450       return 033;
 451     case 'f':
 452       return TARGET_FF;
 453     case 'n':
 454       return TARGET_NEWLINE;
 455     case 'r':
 456       return TARGET_CR;
 457     case 't':
 458       return TARGET_TAB;
 459     case 'v':
 460       return TARGET_VT;
 461     case '\n':
 462       return -2;
 463     case 0:
 464       (*string_ptr)--;
 465       return 0;
 466     case '^':
 467       c = *(*string_ptr)++;
 468       if (c == '\\')
 469         c = parse_escape (string_ptr);
 470       if (c == '?')
 471         return 0177;
 472       return (c & 0200) | (c & 037);
 473
 474     case '0':
 475     case '1':
 476     case '2':
 477     case '3':
 478     case '4':
 479     case '5':
 480     case '6':
 481     case '7':
 482       {
 483         int i = c - '0';
 484         int count = 0;
 485         while (++count < 3)
 486           {
 487             c = *(*string_ptr)++;
 488             if (c >= '0' && c <= '7')
 489               i = (i << 3) + c - '0';
 490             else
 491               {
 492                 (*string_ptr)--;
 493                 break;
 494               }
 495           }
 496         if ((i & ~((1 << CHAR_TYPE_SIZE) - 1)) != 0)
 497           {
 498             i &= (1 << CHAR_TYPE_SIZE) - 1;
 499             warning ("octal character constant does not fit in a byte");
 500           }
 501         return i;
 502       }
 503     case 'x':
 504       {
 505         int i = 0;
 506         for (;;)
 507           {
 508             c = *(*string_ptr)++;
 509             if (hex_p (c))
 510               i = (i << 4) + hex_value (c);
 511             else
 512               {
 513                 (*string_ptr)--;
 514                 break;
 515               }
 516           }
 517         if ((i & ~((1 << BITS_PER_UNIT) - 1)) != 0)
 518           {
 519             i &= (1 << BITS_PER_UNIT) - 1;
 520             warning ("hex character constant does not fit in a byte");
 521           }
 522         return i;
 523       }
 524     default:
 525       return c;
 526     }
 527 }
 528
 529 static void
 530 yyerror (msgid)
 531      const char *msgid;
 532 {
 533   error ("%s", _(msgid));
 534   longjmp (parse_return_error, 1);
 535 }
 536 \f
 537 /* This page contains the entry point to this file.  */
 538
 539 /* Parse STRING as an expression, and complain if this fails
 540    to use up all of the contents of STRING.  */
 541 /* We do not support C comments.  They should be removed before
 542    this function is called.  */
 543
 544 int
 545 parse_c_expression (string)
 546      const char *string;
 547 {
 548   lexptr = string;
 549
 550   if (lexptr == 0 || *lexptr == 0) {
 551     error ("empty #if expression");
 552     return 0;                   /* don't include the #if group */
 553   }
 554
 555   /* if there is some sort of scanning error, just return 0 and assume
 556      the parsing routine has printed an error message somewhere.
 557      there is surely a better thing to do than this.     */
 558   if (setjmp (parse_return_error))
 559     return 0;
 560
 561   if (yyparse ())
 562     return 0;                   /* actually this is never reached
 563                                    the way things stand. */
 564   if (*lexptr)
 565     error ("Junk after end of expression.");
 566
 567   return expression_value;      /* set by yyparse () */
 568 }