src/expr.c

   1 /* expr -- evaluate expressions.
   2    Copyright (C) 86, 1991-1997, 1999-2008 Free Software Foundation, Inc.
   3
   4    This program is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation, either version 3 of the License, or
   7    (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* Author: Mike Parker.
  18    Modified for arbitrary-precision calculation by James Youngman.
  19
  20    This program evaluates expressions.  Each token (operator, operand,
  21    parenthesis) of the expression must be a seperate argument.  The
  22    parser used is a reasonably general one, though any incarnation of
  23    it is language-specific.  It is especially nice for expressions.
  24
  25    No parse tree is needed; a new node is evaluated immediately.
  26    One function can handle multiple operators all of equal precedence,
  27    provided they all associate ((x op x) op x).
  28
  29    Define EVAL_TRACE to print an evaluation trace.  */
  30
  31 #include <config.h>
  32 #include <stdio.h>
  33 #include <sys/types.h>
  34 #include "system.h"
  35
  36 #include <regex.h>
  37 #include "error.h"
  38 #include "long-options.h"
  39 #include "quotearg.h"
  40 #include "strnumcmp.h"
  41 #include "xstrtol.h"
  42
  43 /* Various parts of this code assume size_t fits into unsigned long
  44    int, the widest unsigned type that GMP supports.  */
  45 verify (SIZE_MAX <= ULONG_MAX);
  46
  47 static void integer_overflow (char) ATTRIBUTE_NORETURN;
  48
  49 #ifndef HAVE_GMP
  50 # define HAVE_GMP 0
  51 #endif
  52
  53 #if HAVE_GMP
  54 # include <gmp.h>
  55 #else
  56 /* Approximate gmp.h well enough for expr.c's purposes.  */
  57 typedef intmax_t mpz_t[1];
  58 static void mpz_clear (mpz_t z) {}
  59 static void mpz_init_set_ui (mpz_t z, unsigned long int i) { z[0] = i; }
  60 static int
  61 mpz_init_set_str (mpz_t z, char *s, int base)
  62 {
  63   return xstrtoimax (s, NULL, base, z, NULL) == LONGINT_OK ? 0 : -1;
  64 }
  65 static void
  66 mpz_add (mpz_t r, mpz_t a0, mpz_t b0)
  67 {
  68   intmax_t a = a0[0];
  69   intmax_t b = b0[0];
  70   intmax_t val = a + b;
  71   if ((val < a) != (b < 0))
  72     integer_overflow ('+');
  73   r[0] = val;
  74 }
  75 static void
  76 mpz_sub (mpz_t r, mpz_t a0, mpz_t b0)
  77 {
  78   intmax_t a = a0[0];
  79   intmax_t b = b0[0];
  80   intmax_t val = a - b;
  81   if ((a < val) != (b < 0))
  82     integer_overflow ('-');
  83   r[0] = val;
  84 }
  85 static void
  86 mpz_mul (mpz_t r, mpz_t a0, mpz_t b0)
  87 {
  88   intmax_t a = a0[0];
  89   intmax_t b = b0[0];
  90   intmax_t val = a * b;
  91   if (! (a == 0 || b == 0
  92          || ((val < 0) == ((a < 0) ^ (b < 0)) && val / a == b)))
  93     integer_overflow ('*');
  94   r[0] = val;
  95 }
  96 static void
  97 mpz_tdiv_q (mpz_t r, mpz_t a0, mpz_t b0)
  98 {
  99   intmax_t a = a0[0];
 100   intmax_t b = b0[0];
 101
 102   /* Some x86-style hosts raise an exception for INT_MIN / -1.  */
 103   if (a < - INTMAX_MAX && b == -1)
 104     integer_overflow ('/');
 105   r[0] = a / b;
 106 }
 107 static void
 108 mpz_tdiv_r (mpz_t r, mpz_t a0, mpz_t b0)
 109 {
 110   intmax_t a = a0[0];
 111   intmax_t b = b0[0];
 112
 113   /* Some x86-style hosts raise an exception for INT_MIN % -1.  */
 114   r[0] = a < - INTMAX_MAX && b == -1 ? 0 : a % b;
 115 }
 116 static char *
 117 mpz_get_str (char const *str, int base, mpz_t z)
 118 {
 119   char buf[INT_BUFSIZE_BOUND (intmax_t)];
 120   return xstrdup (imaxtostr (z[0], buf));
 121 }
 122 static int
 123 mpz_sgn (mpz_t z)
 124 {
 125   return z[0] < 0 ? -1 : 0 < z[0];
 126 }
 127 static int
 128 mpz_fits_ulong_p (mpz_t z)
 129 {
 130   return 0 <= z[0] && z[0] <= ULONG_MAX;
 131 }
 132 static unsigned long int
 133 mpz_get_ui (mpz_t z)
 134 {
 135   return z[0];
 136 }
 137 static int
 138 mpz_out_str (FILE *stream, int base, mpz_t z)
 139 {
 140   char buf[INT_BUFSIZE_BOUND (intmax_t)];
 141   return fputs (imaxtostr (z[0], buf), stream) != EOF;
 142 }
 143 #endif
 144
 145 /* The official name of this program (e.g., no `g' prefix).  */
 146 #define PROGRAM_NAME "expr"
 147
 148 #define AUTHORS \
 149   proper_name ("Mike Parker"), \
 150   proper_name ("James Youngman"), \
 151   proper_name ("Paul Eggert")
 152
 153 /* Exit statuses.  */
 154 enum
 155   {
 156     /* Invalid expression: e.g., its form does not conform to the
 157        grammar for expressions.  Our grammar is an extension of the
 158        POSIX grammar.  */
 159     EXPR_INVALID = 2,
 160
 161     /* An internal error occurred, e.g., arithmetic overflow, storage
 162        exhaustion.  */
 163     EXPR_FAILURE
 164   };
 165
 166 /* The kinds of value we can have.  */
 167 enum valtype
 168 {
 169   integer,
 170   string
 171 };
 172 typedef enum valtype TYPE;
 173
 174 /* A value is.... */
 175 struct valinfo
 176 {
 177   TYPE type;                    /* Which kind. */
 178   union
 179   {                             /* The value itself. */
 180     mpz_t i;
 181     char *s;
 182   } u;
 183 };
 184 typedef struct valinfo VALUE;
 185
 186 /* The arguments given to the program, minus the program name.  */
 187 static char **args;
 188
 189 static VALUE *eval (bool);
 190 static bool nomoreargs (void);
 191 static bool null (VALUE *v);
 192 static void printv (VALUE *v);
 193
 194 void
 195 usage (int status)
 196 {
 197   if (status != EXIT_SUCCESS)
 198     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 199              program_name);
 200   else
 201     {
 202       printf (_("\
 203 Usage: %s EXPRESSION\n\
 204   or:  %s OPTION\n\
 205 "),
 206               program_name, program_name);
 207       putchar ('\n');
 208       fputs (HELP_OPTION_DESCRIPTION, stdout);
 209       fputs (VERSION_OPTION_DESCRIPTION, stdout);
 210       fputs (_("\
 211 \n\
 212 Print the value of EXPRESSION to standard output.  A blank line below\n\
 213 separates increasing precedence groups.  EXPRESSION may be:\n\
 214 \n\
 215   ARG1 | ARG2       ARG1 if it is neither null nor 0, otherwise ARG2\n\
 216 \n\
 217   ARG1 & ARG2       ARG1 if neither argument is null or 0, otherwise 0\n\
 218 "), stdout);
 219       fputs (_("\
 220 \n\
 221   ARG1 < ARG2       ARG1 is less than ARG2\n\
 222   ARG1 <= ARG2      ARG1 is less than or equal to ARG2\n\
 223   ARG1 = ARG2       ARG1 is equal to ARG2\n\
 224   ARG1 != ARG2      ARG1 is unequal to ARG2\n\
 225   ARG1 >= ARG2      ARG1 is greater than or equal to ARG2\n\
 226   ARG1 > ARG2       ARG1 is greater than ARG2\n\
 227 "), stdout);
 228       fputs (_("\
 229 \n\
 230   ARG1 + ARG2       arithmetic sum of ARG1 and ARG2\n\
 231   ARG1 - ARG2       arithmetic difference of ARG1 and ARG2\n\
 232 "), stdout);
 233       /* Tell xgettext that the "% A" below is not a printf-style
 234          format string:  xgettext:no-c-format */
 235       fputs (_("\
 236 \n\
 237   ARG1 * ARG2       arithmetic product of ARG1 and ARG2\n\
 238   ARG1 / ARG2       arithmetic quotient of ARG1 divided by ARG2\n\
 239   ARG1 % ARG2       arithmetic remainder of ARG1 divided by ARG2\n\
 240 "), stdout);
 241       fputs (_("\
 242 \n\
 243   STRING : REGEXP   anchored pattern match of REGEXP in STRING\n\
 244 \n\
 245   match STRING REGEXP        same as STRING : REGEXP\n\
 246   substr STRING POS LENGTH   substring of STRING, POS counted from 1\n\
 247   index STRING CHARS         index in STRING where any CHARS is found, or 0\n\
 248   length STRING              length of STRING\n\
 249 "), stdout);
 250       fputs (_("\
 251   + TOKEN                    interpret TOKEN as a string, even if it is a\n\
 252                                keyword like `match' or an operator like `/'\n\
 253 \n\
 254   ( EXPRESSION )             value of EXPRESSION\n\
 255 "), stdout);
 256       fputs (_("\
 257 \n\
 258 Beware that many operators need to be escaped or quoted for shells.\n\
 259 Comparisons are arithmetic if both ARGs are numbers, else lexicographical.\n\
 260 Pattern matches return the string matched between \\( and \\) or null; if\n\
 261 \\( and \\) are not used, they return the number of characters matched or 0.\n\
 262 "), stdout);
 263       fputs (_("\
 264 \n\
 265 Exit status is 0 if EXPRESSION is neither null nor 0, 1 if EXPRESSION is null\n\
 266 or 0, 2 if EXPRESSION is syntactically invalid, and 3 if an error occurred.\n\
 267 "), stdout);
 268       emit_bug_reporting_address ();
 269     }
 270   exit (status);
 271 }
 272
 273 /* Report a syntax error and exit.  */
 274 static void
 275 syntax_error (void)
 276 {
 277   error (EXPR_INVALID, 0, _("syntax error"));
 278 }
 279
 280 /* Report an integer overflow for operation OP and exit.  */
 281 static void
 282 integer_overflow (char op)
 283 {
 284   error (EXPR_FAILURE, ERANGE, "%c", op);
 285   abort (); /* notreached */
 286 }
 287
 288 static void die (int errno_val, char const *msg)
 289   ATTRIBUTE_NORETURN;
 290 static void
 291 die (int errno_val, char const *msg)
 292 {
 293   error (EXPR_FAILURE, errno_val, "%s", msg);
 294   abort (); /* notreached */
 295 }
 296
 297 int
 298 main (int argc, char **argv)
 299 {
 300   VALUE *v;
 301
 302   initialize_main (&argc, &argv);
 303   set_program_name (argv[0]);
 304   setlocale (LC_ALL, "");
 305   bindtextdomain (PACKAGE, LOCALEDIR);
 306   textdomain (PACKAGE);
 307
 308   initialize_exit_failure (EXPR_FAILURE);
 309   atexit (close_stdout);
 310
 311   parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, VERSION,
 312                       usage, AUTHORS, (char const *) NULL);
 313   /* The above handles --help and --version.
 314      Since there is no other invocation of getopt, handle `--' here.  */
 315   if (argc > 1 && STREQ (argv[1], "--"))
 316     {
 317       --argc;
 318       ++argv;
 319     }
 320
 321   if (argc <= 1)
 322     {
 323       error (0, 0, _("missing operand"));
 324       usage (EXPR_INVALID);
 325     }
 326
 327   args = argv + 1;
 328
 329   v = eval (true);
 330   if (!nomoreargs ())
 331     syntax_error ();
 332   printv (v);
 333
 334   exit (null (v));
 335 }
 336
 337 /* Return a VALUE for I.  */
 338
 339 static VALUE *
 340 int_value (unsigned long int i)
 341 {
 342   VALUE *v = xmalloc (sizeof *v);
 343   v->type = integer;
 344   mpz_init_set_ui (v->u.i, i);
 345   return v;
 346 }
 347
 348 /* Return a VALUE for S.  */
 349
 350 static VALUE *
 351 str_value (char const *s)
 352 {
 353   VALUE *v = xmalloc (sizeof *v);
 354   v->type = string;
 355   v->u.s = xstrdup (s);
 356   return v;
 357 }
 358
 359 /* Free VALUE V, including structure components.  */
 360
 361 static void
 362 freev (VALUE *v)
 363 {
 364   if (v->type == string)
 365     free (v->u.s);
 366   else
 367     mpz_clear (v->u.i);
 368   free (v);
 369 }
 370
 371 /* Print VALUE V.  */
 372
 373 static void
 374 printv (VALUE *v)
 375 {
 376   switch (v->type)
 377     {
 378     case integer:
 379       mpz_out_str (stdout, 10, v->u.i);
 380       putchar ('\n');
 381       break;
 382     case string:
 383       puts (v->u.s);
 384       break;
 385     default:
 386       abort ();
 387     }
 388 }
 389
 390 /* Return true if V is a null-string or zero-number.  */
 391
 392 static bool
 393 null (VALUE *v)
 394 {
 395   switch (v->type)
 396     {
 397     case integer:
 398       return mpz_sgn (v->u.i) == 0;
 399     case string:
 400       {
 401         char const *cp = v->u.s;
 402         if (*cp == '\0')
 403           return true;
 404
 405         cp += (*cp == '-');
 406
 407         do
 408           {
 409             if (*cp != '0')
 410               return false;
 411           }
 412         while (*++cp);
 413
 414         return true;
 415       }
 416     default:
 417       abort ();
 418     }
 419 }
 420
 421 /* Return true if CP takes the form of an integer.  */
 422
 423 static bool
 424 looks_like_integer (char const *cp)
 425 {
 426   cp += (*cp == '-');
 427
 428   do
 429     if (! ISDIGIT (*cp))
 430       return false;
 431   while (*++cp);
 432
 433   return true;
 434 }
 435
 436 /* Coerce V to a string value (can't fail).  */
 437
 438 static void
 439 tostring (VALUE *v)
 440 {
 441   switch (v->type)
 442     {
 443     case integer:
 444       {
 445         char *s = mpz_get_str (NULL, 10, v->u.i);
 446         mpz_clear (v->u.i);
 447         v->u.s = s;
 448         v->type = string;
 449       }
 450       break;
 451     case string:
 452       break;
 453     default:
 454       abort ();
 455     }
 456 }
 457
 458 /* Coerce V to an integer value.  Return true on success, false on failure.  */
 459
 460 static bool
 461 toarith (VALUE *v)
 462 {
 463   switch (v->type)
 464     {
 465     case integer:
 466       return true;
 467     case string:
 468       {
 469         char *s = v->u.s;
 470
 471         if (! looks_like_integer (s))
 472           return false;
 473         if (mpz_init_set_str (v->u.i, s, 10) != 0 && !HAVE_GMP)
 474           error (EXPR_FAILURE, ERANGE, "%s", s);
 475         free (s);
 476         v->type = integer;
 477         return true;
 478       }
 479     default:
 480       abort ();
 481     }
 482 }
 483
 484 /* Extract a size_t value from a integer value I.
 485    If the value is negative, return SIZE_MAX.
 486    If the value is too large, return SIZE_MAX - 1.  */
 487 static size_t
 488 getsize (mpz_t i)
 489 {
 490   if (mpz_sgn (i) < 0)
 491     return SIZE_MAX;
 492   if (mpz_fits_ulong_p (i))
 493     {
 494       unsigned long int ul = mpz_get_ui (i);
 495       if (ul < SIZE_MAX)
 496         return ul;
 497     }
 498   return SIZE_MAX - 1;
 499 }
 500
 501 /* Return true and advance if the next token matches STR exactly.
 502    STR must not be NULL.  */
 503
 504 static bool
 505 nextarg (char const *str)
 506 {
 507   if (*args == NULL)
 508     return false;
 509   else
 510     {
 511       bool r = STREQ (*args, str);
 512       args += r;
 513       return r;
 514     }
 515 }
 516
 517 /* Return true if there no more tokens.  */
 518
 519 static bool
 520 nomoreargs (void)
 521 {
 522   return *args == 0;
 523 }
 524
 525 #ifdef EVAL_TRACE
 526 /* Print evaluation trace and args remaining.  */
 527
 528 static void
 529 trace (fxn)
 530      char *fxn;
 531 {
 532   char **a;
 533
 534   printf ("%s:", fxn);
 535   for (a = args; *a; a++)
 536     printf (" %s", *a);
 537   putchar ('\n');
 538 }
 539 #endif
 540
 541 /* Do the : operator.
 542    SV is the VALUE for the lhs (the string),
 543    PV is the VALUE for the rhs (the pattern).  */
 544
 545 static VALUE *
 546 docolon (VALUE *sv, VALUE *pv)
 547 {
 548   VALUE *v IF_LINT (= NULL);
 549   const char *errmsg;
 550   struct re_pattern_buffer re_buffer;
 551   char fastmap[UCHAR_MAX + 1];
 552   struct re_registers re_regs;
 553   regoff_t matchlen;
 554
 555   tostring (sv);
 556   tostring (pv);
 557
 558   re_regs.num_regs = 0;
 559   re_regs.start = NULL;
 560   re_regs.end = NULL;
 561
 562   re_buffer.buffer = NULL;
 563   re_buffer.allocated = 0;
 564   re_buffer.fastmap = fastmap;
 565   re_buffer.translate = NULL;
 566   re_syntax_options =
 567     RE_SYNTAX_POSIX_BASIC & ~RE_CONTEXT_INVALID_DUP & ~RE_NO_EMPTY_RANGES;
 568   errmsg = re_compile_pattern (pv->u.s, strlen (pv->u.s), &re_buffer);
 569   if (errmsg)
 570     error (EXPR_INVALID, 0, "%s", errmsg);
 571   re_buffer.newline_anchor = 0;
 572
 573   matchlen = re_match (&re_buffer, sv->u.s, strlen (sv->u.s), 0, &re_regs);
 574   if (0 <= matchlen)
 575     {
 576       /* Were \(...\) used? */
 577       if (re_buffer.re_nsub > 0)
 578         {
 579           sv->u.s[re_regs.end[1]] = '\0';
 580           v = str_value (sv->u.s + re_regs.start[1]);
 581         }
 582       else
 583         v = int_value (matchlen);
 584     }
 585   else if (matchlen == -1)
 586     {
 587       /* Match failed -- return the right kind of null.  */
 588       if (re_buffer.re_nsub > 0)
 589         v = str_value ("");
 590       else
 591         v = int_value (0);
 592     }
 593   else
 594     error (EXPR_FAILURE,
 595            (matchlen == -2 ? errno : EOVERFLOW),
 596            _("error in regular expression matcher"));
 597
 598   if (0 < re_regs.num_regs)
 599     {
 600       free (re_regs.start);
 601       free (re_regs.end);
 602     }
 603   re_buffer.fastmap = NULL;
 604   regfree (&re_buffer);
 605   return v;
 606 }
 607
 608 /* Handle bare operands and ( expr ) syntax.  */
 609
 610 static VALUE *
 611 eval7 (bool evaluate)
 612 {
 613   VALUE *v;
 614
 615 #ifdef EVAL_TRACE
 616   trace ("eval7");
 617 #endif
 618   if (nomoreargs ())
 619     syntax_error ();
 620
 621   if (nextarg ("("))
 622     {
 623       v = eval (evaluate);
 624       if (!nextarg (")"))
 625         syntax_error ();
 626       return v;
 627     }
 628
 629   if (nextarg (")"))
 630     syntax_error ();
 631
 632   return str_value (*args++);
 633 }
 634
 635 /* Handle match, substr, index, and length keywords, and quoting "+".  */
 636
 637 static VALUE *
 638 eval6 (bool evaluate)
 639 {
 640   VALUE *l;
 641   VALUE *r;
 642   VALUE *v;
 643   VALUE *i1;
 644   VALUE *i2;
 645
 646 #ifdef EVAL_TRACE
 647   trace ("eval6");
 648 #endif
 649   if (nextarg ("+"))
 650     {
 651       if (nomoreargs ())
 652         syntax_error ();
 653       return str_value (*args++);
 654     }
 655   else if (nextarg ("length"))
 656     {
 657       r = eval6 (evaluate);
 658       tostring (r);
 659       v = int_value (strlen (r->u.s));
 660       freev (r);
 661       return v;
 662     }
 663   else if (nextarg ("match"))
 664     {
 665       l = eval6 (evaluate);
 666       r = eval6 (evaluate);
 667       if (evaluate)
 668         {
 669           v = docolon (l, r);
 670           freev (l);
 671         }
 672       else
 673         v = l;
 674       freev (r);
 675       return v;
 676     }
 677   else if (nextarg ("index"))
 678     {
 679       size_t pos;
 680
 681       l = eval6 (evaluate);
 682       r = eval6 (evaluate);
 683       tostring (l);
 684       tostring (r);
 685       pos = strcspn (l->u.s, r->u.s);
 686       v = int_value (l->u.s[pos] ? pos + 1 : 0);
 687       freev (l);
 688       freev (r);
 689       return v;
 690     }
 691   else if (nextarg ("substr"))
 692     {
 693       size_t llen;
 694       l = eval6 (evaluate);
 695       i1 = eval6 (evaluate);
 696       i2 = eval6 (evaluate);
 697       tostring (l);
 698       llen = strlen (l->u.s);
 699
 700       if (!toarith (i1) || !toarith (i2))
 701         v = str_value ("");
 702       else
 703         {
 704           size_t pos = getsize (i1->u.i);
 705           size_t len = getsize (i2->u.i);
 706
 707           if (llen < pos || pos == 0 || len == 0 || len == SIZE_MAX)
 708             v = str_value ("");
 709           else
 710             {
 711               size_t vlen = MIN (len, llen - pos + 1);
 712               char *vlim;
 713               v = xmalloc (sizeof *v);
 714               v->type = string;
 715               v->u.s = xmalloc (vlen + 1);
 716               vlim = mempcpy (v->u.s, l->u.s + pos - 1, vlen);
 717               *vlim = '\0';
 718             }
 719         }
 720       freev (l);
 721       freev (i1);
 722       freev (i2);
 723       return v;
 724     }
 725   else
 726     return eval7 (evaluate);
 727 }
 728
 729 /* Handle : operator (pattern matching).
 730    Calls docolon to do the real work.  */
 731
 732 static VALUE *
 733 eval5 (bool evaluate)
 734 {
 735   VALUE *l;
 736   VALUE *r;
 737   VALUE *v;
 738
 739 #ifdef EVAL_TRACE
 740   trace ("eval5");
 741 #endif
 742   l = eval6 (evaluate);
 743   while (1)
 744     {
 745       if (nextarg (":"))
 746         {
 747           r = eval6 (evaluate);
 748           if (evaluate)
 749             {
 750               v = docolon (l, r);
 751               freev (l);
 752               l = v;
 753             }
 754           freev (r);
 755         }
 756       else
 757         return l;
 758     }
 759 }
 760
 761 /* Handle *, /, % operators.  */
 762
 763 static VALUE *
 764 eval4 (bool evaluate)
 765 {
 766   VALUE *l;
 767   VALUE *r;
 768   enum { multiply, divide, mod } fxn;
 769
 770 #ifdef EVAL_TRACE
 771   trace ("eval4");
 772 #endif
 773   l = eval5 (evaluate);
 774   while (1)
 775     {
 776       if (nextarg ("*"))
 777         fxn = multiply;
 778       else if (nextarg ("/"))
 779         fxn = divide;
 780       else if (nextarg ("%"))
 781         fxn = mod;
 782       else
 783         return l;
 784       r = eval5 (evaluate);
 785       if (evaluate)
 786         {
 787           if (!toarith (l) || !toarith (r))
 788             error (EXPR_INVALID, 0, _("non-numeric argument"));
 789           if (fxn != multiply && mpz_sgn (r->u.i) == 0)
 790             error (EXPR_INVALID, 0, _("division by zero"));
 791           ((fxn == multiply ? mpz_mul
 792             : fxn == divide ? mpz_tdiv_q
 793             : mpz_tdiv_r)
 794            (l->u.i, l->u.i, r->u.i));
 795         }
 796       freev (r);
 797     }
 798 }
 799
 800 /* Handle +, - operators.  */
 801
 802 static VALUE *
 803 eval3 (bool evaluate)
 804 {
 805   VALUE *l;
 806   VALUE *r;
 807   enum { plus, minus } fxn;
 808
 809 #ifdef EVAL_TRACE
 810   trace ("eval3");
 811 #endif
 812   l = eval4 (evaluate);
 813   while (1)
 814     {
 815       if (nextarg ("+"))
 816         fxn = plus;
 817       else if (nextarg ("-"))
 818         fxn = minus;
 819       else
 820         return l;
 821       r = eval4 (evaluate);
 822       if (evaluate)
 823         {
 824           if (!toarith (l) || !toarith (r))
 825             error (EXPR_INVALID, 0, _("non-numeric argument"));
 826           (fxn == plus ? mpz_add : mpz_sub) (l->u.i, l->u.i, r->u.i);
 827         }
 828       freev (r);
 829     }
 830 }
 831
 832 /* Handle comparisons.  */
 833
 834 static VALUE *
 835 eval2 (bool evaluate)
 836 {
 837   VALUE *l;
 838
 839 #ifdef EVAL_TRACE
 840   trace ("eval2");
 841 #endif
 842   l = eval3 (evaluate);
 843   while (1)
 844     {
 845       VALUE *r;
 846       enum
 847         {
 848           less_than, less_equal, equal, not_equal, greater_equal, greater_than
 849         } fxn;
 850       bool val = false;
 851
 852       if (nextarg ("<"))
 853         fxn = less_than;
 854       else if (nextarg ("<="))
 855         fxn = less_equal;
 856       else if (nextarg ("=") || nextarg ("=="))
 857         fxn = equal;
 858       else if (nextarg ("!="))
 859         fxn = not_equal;
 860       else if (nextarg (">="))
 861         fxn = greater_equal;
 862       else if (nextarg (">"))
 863         fxn = greater_than;
 864       else
 865         return l;
 866       r = eval3 (evaluate);
 867
 868       if (evaluate)
 869         {
 870           int cmp;
 871           tostring (l);
 872           tostring (r);
 873
 874           if (looks_like_integer (l->u.s) && looks_like_integer (r->u.s))
 875             cmp = strintcmp (l->u.s, r->u.s);
 876           else
 877             {
 878               errno = 0;
 879               cmp = strcoll (l->u.s, r->u.s);
 880
 881               if (errno)
 882                 {
 883                   error (0, errno, _("string comparison failed"));
 884                   error (0, 0, _("set LC_ALL='C' to work around the problem"));
 885                   error (EXPR_INVALID, 0,
 886                          _("the strings compared were %s and %s"),
 887                          quotearg_n_style (0, locale_quoting_style, l->u.s),
 888                          quotearg_n_style (1, locale_quoting_style, r->u.s));
 889                 }
 890             }
 891
 892           switch (fxn)
 893             {
 894             case less_than:     val = (cmp <  0); break;
 895             case less_equal:    val = (cmp <= 0); break;
 896             case equal:         val = (cmp == 0); break;
 897             case not_equal:     val = (cmp != 0); break;
 898             case greater_equal: val = (cmp >= 0); break;
 899             case greater_than:  val = (cmp >  0); break;
 900             default: abort ();
 901             }
 902         }
 903
 904       freev (l);
 905       freev (r);
 906       l = int_value (val);
 907     }
 908 }
 909
 910 /* Handle &.  */
 911
 912 static VALUE *
 913 eval1 (bool evaluate)
 914 {
 915   VALUE *l;
 916   VALUE *r;
 917
 918 #ifdef EVAL_TRACE
 919   trace ("eval1");
 920 #endif
 921   l = eval2 (evaluate);
 922   while (1)
 923     {
 924       if (nextarg ("&"))
 925         {
 926           r = eval2 (evaluate & ~ null (l));
 927           if (null (l) || null (r))
 928             {
 929               freev (l);
 930               freev (r);
 931               l = int_value (0);
 932             }
 933           else
 934             freev (r);
 935         }
 936       else
 937         return l;
 938     }
 939 }
 940
 941 /* Handle |.  */
 942
 943 static VALUE *
 944 eval (bool evaluate)
 945 {
 946   VALUE *l;
 947   VALUE *r;
 948
 949 #ifdef EVAL_TRACE
 950   trace ("eval");
 951 #endif
 952   l = eval1 (evaluate);
 953   while (1)
 954     {
 955       if (nextarg ("|"))
 956         {
 957           r = eval1 (evaluate & null (l));
 958           if (null (l))
 959             {
 960               freev (l);
 961               l = r;
 962               if (null (l))
 963                 {
 964                   freev (l);
 965                   l = int_value (0);
 966                 }
 967             }
 968           else
 969             freev (r);
 970         }
 971       else
 972         return l;
 973     }
 974 }