src/getargs.c

   1 /* Parse command line arguments for Bison.
   2
   3    Copyright (C) 1984, 1986, 1989, 1992, 2000-2012 Free Software
   4    Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    This program is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any 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, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include <config.h>
  22 #include "system.h"
  23 #include "output.h"
  24
  25 #include <argmatch.h>
  26 #include <c-strcase.h>
  27 #include <configmake.h>
  28 #include <error.h>
  29 #include <getopt.h>
  30 #include <progname.h>
  31
  32 #include "complain.h"
  33 #include "files.h"
  34 #include "getargs.h"
  35 #include "muscle-tab.h"
  36 #include "quote.h"
  37 #include "uniqstr.h"
  38
  39 bool defines_flag;
  40 bool graph_flag;
  41 bool xml_flag;
  42 bool no_lines_flag;
  43 bool token_table_flag;
  44 bool yacc_flag; /* for -y */
  45
  46 bool nondeterministic_parser = false;
  47 bool glr_parser = false;
  48
  49 int report_flag = report_none;
  50 int trace_flag = trace_none;
  51
  52 static struct bison_language const valid_languages[] = {
  53   { "c", "c-skel.m4", ".c", ".h", true },
  54   { "c++", "c++-skel.m4", ".cc", ".hh", true },
  55   { "java", "java-skel.m4", ".java", ".java", false },
  56   { "", "", "", "", false }
  57 };
  58
  59 int skeleton_prio = default_prio;
  60 const char *skeleton = NULL;
  61 int language_prio = default_prio;
  62 struct bison_language const *language = &valid_languages[0];
  63 const char *include = NULL;
  64
  65
  66 /** Decode an option's set of keys.
  67  *
  68  *  \param option   option being decoded.
  69  *  \param keys     array of valid subarguments.
  70  *  \param values   array of corresponding (int) values.
  71  *  \param all      the all value.
  72  *  \param flags    the flags to update
  73  *  \param args     comma separated list of effective subarguments to decode.
  74  *                  If 0, then activate all the flags.
  75  *
  76  *  If VALUE != 0 then KEY sets flags and no-KEY clears them.
  77  *  If VALUE == 0 then KEY clears all flags from \c all and no-KEY sets all
  78  *  flags from \c all.  Thus no-none = all and no-all = none.
  79  */
  80 static void
  81 flags_argmatch (const char *option,
  82                 const char * const keys[], const int values[],
  83                 int all, int *flags, char *args)
  84 {
  85   if (args)
  86     {
  87       args = strtok (args, ",");
  88       while (args)
  89         {
  90           int value = 0;
  91           int *save_flags = flags;
  92           int no = STRPREFIX_LIT ("no-", args) ? 3 : 0;
  93           int err = STRPREFIX_LIT ("error", args + no) ? 5 : 0;
  94
  95           if (err)
  96             flags = &errors_flag;
  97           if (!err || args[no + err++] != '\0')
  98             value = XARGMATCH (option, args + no + err, keys, values);
  99
 100           if (!value)
 101             {
 102             /*  With a simpler 'if (no)' version, -Werror means -Werror=all
 103                 (or rather, -Werror=no-none, but that syntax is invalid).
 104                 The difference is:
 105                   - Werror activates all errors, but not the warnings
 106                   - Werror=all activates errors, and all warnings */
 107               if (no ? !err : err)
 108                 *flags |= all;
 109               else
 110                 *flags &= ~all;
 111             }
 112           else
 113             {
 114               if (no)
 115                 *flags &= ~value;
 116               else
 117                 {
 118                   if (err)
 119                     warnings_flag |= value;
 120                   *flags |= value;
 121                 }
 122             }
 123           flags = save_flags;
 124           args = strtok (NULL, ",");
 125         }
 126     }
 127   else
 128     *flags |= all;
 129 }
 130
 131 /** Decode a set of sub arguments.
 132  *
 133  *  \param FlagName  the flag familly to update.
 134  *  \param Args      the effective sub arguments to decode.
 135  *  \param All       the "all" value.
 136  *
 137  *  \arg FlagName_args   the list of keys.
 138  *  \arg FlagName_types  the list of values.
 139  *  \arg FlagName_flag   the flag to update.
 140  */
 141 #define FLAGS_ARGMATCH(FlagName, Args, All)                             \
 142   flags_argmatch ("--" #FlagName, FlagName ## _args, FlagName ## _types, \
 143                   All, &FlagName ## _flag, Args)
 144
 145
 146 /*----------------------.
 147 | --report's handling.  |
 148 `----------------------*/
 149
 150 static const char * const report_args[] =
 151 {
 152   /* In a series of synonyms, present the most meaningful first, so
 153      that argmatch_valid be more readable.  */
 154   "none",
 155   "state", "states",
 156   "itemset", "itemsets",
 157   "lookahead", "lookaheads", "look-ahead",
 158   "solved",
 159   "all",
 160   0
 161 };
 162
 163 static const int report_types[] =
 164 {
 165   report_none,
 166   report_states, report_states,
 167   report_states | report_itemsets, report_states | report_itemsets,
 168   report_states | report_lookahead_tokens,
 169   report_states | report_lookahead_tokens,
 170   report_states | report_lookahead_tokens,
 171   report_states | report_solved_conflicts,
 172   report_all
 173 };
 174
 175 ARGMATCH_VERIFY (report_args, report_types);
 176
 177
 178 /*---------------------.
 179 | --trace's handling.  |
 180 `---------------------*/
 181
 182 static const char * const trace_args[] =
 183 {
 184   /* In a series of synonyms, present the most meaningful first, so
 185      that argmatch_valid be more readable.  */
 186   "none       - no traces",
 187   "scan       - grammar scanner traces",
 188   "parse      - grammar parser traces",
 189   "automaton  - construction of the automaton",
 190   "bitsets    - use of bitsets",
 191   "grammar    - reading, reducing the grammar",
 192   "resource   - memory consumption (where available)",
 193   "sets       - grammar sets: firsts, nullable etc.",
 194   "muscles    - m4 definitions passed to the skeleton",
 195   "tools      - m4 invocation",
 196   "m4         - m4 traces",
 197   "skeleton   - skeleton postprocessing",
 198   "time       - time consumption",
 199   "ielr       - IELR conversion",
 200   "all        - all of the above",
 201   0
 202 };
 203
 204 static const int trace_types[] =
 205 {
 206   trace_none,
 207   trace_scan,
 208   trace_parse,
 209   trace_automaton,
 210   trace_bitsets,
 211   trace_grammar,
 212   trace_resource,
 213   trace_sets,
 214   trace_muscles,
 215   trace_tools,
 216   trace_m4,
 217   trace_skeleton,
 218   trace_time,
 219   trace_ielr,
 220   trace_all
 221 };
 222
 223 ARGMATCH_VERIFY (trace_args, trace_types);
 224
 225
 226 /*------------------------.
 227 | --warnings's handling.  |
 228 `------------------------*/
 229
 230 static const char * const warnings_args[] =
 231 {
 232   /* In a series of synonyms, present the most meaningful first, so
 233      that argmatch_valid be more readable.  */
 234   "none            - no warnings",
 235   "midrule-values  - unset or unused midrule values",
 236   "yacc            - incompatibilities with POSIX Yacc",
 237   "conflicts-sr    - S/R conflicts",
 238   "conflicts-rr    - R/R conflicts",
 239   "deprecated      - obsolete constructs",
 240   "other           - all other warnings",
 241   "all             - all of the above",
 242   "error           - warnings are errors",
 243   0
 244 };
 245
 246 static const int warnings_types[] =
 247 {
 248   Wnone,
 249   Wmidrule_values,
 250   Wyacc,
 251   Wconflicts_sr,
 252   Wconflicts_rr,
 253   Wdeprecated,
 254   Wother,
 255   Wall,
 256   Werror
 257 };
 258
 259 ARGMATCH_VERIFY (warnings_args, warnings_types);
 260
 261 /*-------------------------------------------.
 262 | Display the help message and exit STATUS.  |
 263 `-------------------------------------------*/
 264
 265 static void usage (int) ATTRIBUTE_NORETURN;
 266
 267 static void
 268 usage (int status)
 269 {
 270   if (status != 0)
 271     fprintf (stderr, _("Try `%s --help' for more information.\n"),
 272              program_name);
 273   else
 274     {
 275       /* For ../build-aux/cross-options.pl to work, use the format:
 276                 ^  -S, --long[=ARGS] (whitespace)
 277          A --long option is required.
 278          Otherwise, add exceptions to ../build-aux/cross-options.pl.  */
 279
 280       printf (_("Usage: %s [OPTION]... FILE\n"), program_name);
 281       fputs (_("\
 282 Generate a deterministic LR or generalized LR (GLR) parser employing\n\
 283 LALR(1), IELR(1), or canonical LR(1) parser tables.  IELR(1) and\n\
 284 canonical LR(1) support is experimental.\n\
 285 \n\
 286 "), stdout);
 287
 288       fputs (_("\
 289 Mandatory arguments to long options are mandatory for short options too.\n\
 290 "), stdout);
 291       fputs (_("\
 292 The same is true for optional arguments.\n\
 293 "), stdout);
 294
 295       fputs (_("\
 296 \n\
 297 Operation modes:\n\
 298   -h, --help                 display this help and exit\n\
 299   -V, --version              output version information and exit\n\
 300       --print-localedir      output directory containing locale-dependent data\n\
 301       --print-datadir        output directory containing skeletons and XSLT\n\
 302   -y, --yacc                 emulate POSIX Yacc\n\
 303   -W, --warnings[=CATEGORY]  report the warnings falling in CATEGORY\n\
 304 \n\
 305 "), stdout);
 306
 307       fputs (_("\
 308 Parser:\n\
 309   -L, --language=LANGUAGE          specify the output programming language\n\
 310                                    (this is an experimental feature)\n\
 311   -S, --skeleton=FILE              specify the skeleton to use\n\
 312   -t, --debug                      instrument the parser for tracing\n\
 313                                    same as `-Dparse.trace'\n\
 314       --locations                  enable location support\n\
 315   -D, --define=NAME[=VALUE]        similar to '%define NAME \"VALUE\"'\n\
 316   -F, --force-define=NAME[=VALUE]  override '%define NAME \"VALUE\"'\n\
 317   -p, --name-prefix=PREFIX         prepend PREFIX to the external symbols\n\
 318                                    deprecated by '-Dapi.prefix=PREFIX'\n\
 319   -l, --no-lines                   don't generate '#line' directives\n\
 320   -k, --token-table                include a table of token names\n\
 321 \n\
 322 "), stdout);
 323
 324       /* Keep -d and --defines separate so that ../build-aux/cross-options.pl
 325        * won't assume that -d also takes an argument.  */
 326       fputs (_("\
 327 Output:\n\
 328       --defines[=FILE]       also produce a header file\n\
 329   -d                         likewise but cannot specify FILE (for POSIX Yacc)\n\
 330   -r, --report=THINGS        also produce details on the automaton\n\
 331       --report-file=FILE     write report to FILE\n\
 332   -v, --verbose              same as `--report=state'\n\
 333   -b, --file-prefix=PREFIX   specify a PREFIX for output files\n\
 334   -o, --output=FILE          leave output to FILE\n\
 335   -g, --graph[=FILE]         also output a graph of the automaton\n\
 336   -x, --xml[=FILE]           also output an XML report of the automaton\n\
 337                              (the XML schema is experimental)\n\
 338 \n\
 339 "), stdout);
 340
 341       fputs (_("\
 342 Warning categories include:\n\
 343   `midrule-values'    unset or unused midrule values\n\
 344   `yacc'              incompatibilities with POSIX Yacc\n\
 345   `conflicts-sr'      S/R conflicts (enabled by default)\n\
 346   `conflicts-rr'      R/R conflicts (enabled by default)\n\
 347   `deprecated'        obsolete constructs\n\
 348   `other'             all other warnings (enabled by default)\n\
 349   `all'               all the warnings\n\
 350   `no-CATEGORY'       turn off warnings in CATEGORY\n\
 351   `none'              turn off all the warnings\n\
 352   `error[=CATEGORY]'  treat warnings as errors\n\
 353 "), stdout);
 354       putc ('\n', stdout);
 355
 356       fputs (_("\
 357 THINGS is a list of comma separated words that can include:\n\
 358   `state'        describe the states\n\
 359   `itemset'      complete the core item sets with their closure\n\
 360   `lookahead'    explicitly associate lookahead tokens to items\n\
 361   `solved'       describe shift/reduce conflicts solving\n\
 362   `all'          include all the above information\n\
 363   `none'         disable the report\n\
 364 "), stdout);
 365
 366       putc ('\n', stdout);
 367       printf (_("Report bugs to <%s>.\n"), PACKAGE_BUGREPORT);
 368       printf (_("%s home page: <%s>.\n"), PACKAGE_NAME, PACKAGE_URL);
 369       fputs (_("General help using GNU software: "
 370                "<http://www.gnu.org/gethelp/>.\n"),
 371              stdout);
 372       /* Don't output this redundant message for English locales.
 373          Note we still output for 'C' so that it gets included in the
 374          man page.  */
 375       const char *lc_messages = setlocale (LC_MESSAGES, NULL);
 376       if (lc_messages && !STREQ (lc_messages, "en_"))
 377         /* TRANSLATORS: Replace LANG_CODE in this URL with your language
 378            code <http://translationproject.org/team/LANG_CODE.html> to
 379            form one of the URLs at http://translationproject.org/team/.
 380            Otherwise, replace the entire URL with your translation team's
 381            email address.  */
 382         fputs (_("Report translation bugs to "
 383                  "<http://translationproject.org/team/>.\n"), stdout);
 384       fputs (_("For complete documentation, run: info bison.\n"), stdout);
 385     }
 386
 387   exit (status);
 388 }
 389
 390
 391 /*------------------------------.
 392 | Display the version message.  |
 393 `------------------------------*/
 394
 395 static void
 396 version (void)
 397 {
 398   /* Some efforts were made to ease the translators' task, please
 399      continue.  */
 400   printf (_("bison (GNU Bison) %s"), VERSION);
 401   putc ('\n', stdout);
 402   fputs (_("Written by Robert Corbett and Richard Stallman.\n"), stdout);
 403   putc ('\n', stdout);
 404
 405   fprintf (stdout,
 406            _("Copyright (C) %d Free Software Foundation, Inc.\n"),
 407            PACKAGE_COPYRIGHT_YEAR);
 408
 409   fputs (_("\
 410 This is free software; see the source for copying conditions.  There is NO\n\
 411 warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
 412 "),
 413          stdout);
 414 }
 415
 416
 417 /*-------------------------------------.
 418 | --skeleton and --language handling.  |
 419 `--------------------------------------*/
 420
 421 void
 422 skeleton_arg (char const *arg, int prio, location loc)
 423 {
 424   if (prio < skeleton_prio)
 425     {
 426       skeleton_prio = prio;
 427       skeleton = arg;
 428     }
 429   else if (prio == skeleton_prio)
 430     complain (&loc, complaint,
 431               _("multiple skeleton declarations are invalid"));
 432 }
 433
 434 void
 435 language_argmatch (char const *arg, int prio, location loc)
 436 {
 437   char const *msg;
 438
 439   if (prio < language_prio)
 440     {
 441       int i;
 442       for (i = 0; valid_languages[i].language[0]; i++)
 443         if (c_strcasecmp (arg, valid_languages[i].language) == 0)
 444           {
 445             language_prio = prio;
 446             language = &valid_languages[i];
 447             return;
 448           }
 449       msg = _("%s: invalid language");
 450     }
 451   else if (language_prio == prio)
 452     msg = _("multiple language declarations are invalid");
 453   else
 454     return;
 455
 456   complain (&loc, complaint, msg, quotearg_colon (arg));
 457 }
 458
 459 /*----------------------.
 460 | Process the options.  |
 461 `----------------------*/
 462
 463 /* Shorts options.
 464    Should be computed from long_options.  */
 465 static char const short_options[] =
 466   "D:"
 467   "F:"
 468   "L:"
 469   "S:"
 470   "T::"
 471   "V"
 472   "W::"
 473   "b:"
 474   "d"
 475   "e"
 476   "g::"
 477   "h"
 478   "k"
 479   "l"
 480   "n"
 481   "o:"
 482   "p:"
 483   "r:"
 484   "t"
 485   "v"
 486   "x::"
 487   "y"
 488   ;
 489
 490 /* Values for long options that do not have single-letter equivalents.  */
 491 enum
 492 {
 493   LOCATIONS_OPTION = CHAR_MAX + 1,
 494   PRINT_LOCALEDIR_OPTION,
 495   PRINT_DATADIR_OPTION,
 496   REPORT_FILE_OPTION
 497 };
 498
 499 static struct option const long_options[] =
 500 {
 501   /* Operation modes. */
 502   { "help",            no_argument,       0,   'h' },
 503   { "version",         no_argument,       0,   'V' },
 504   { "print-localedir", no_argument,       0,   PRINT_LOCALEDIR_OPTION },
 505   { "print-datadir",   no_argument,       0,   PRINT_DATADIR_OPTION   },
 506   { "warnings",        optional_argument, 0,   'W' },
 507
 508   /* Parser. */
 509   { "name-prefix",   required_argument,   0,   'p' },
 510   { "include",       required_argument,   0,   'I' },
 511
 512   /* Output. */
 513   { "file-prefix", required_argument,   0,   'b' },
 514   { "output",      required_argument,   0,   'o' },
 515   { "output-file", required_argument,   0,   'o' },
 516   { "graph",       optional_argument,   0,   'g' },
 517   { "xml",         optional_argument,   0,   'x' },
 518   { "report",      required_argument,   0,   'r' },
 519   { "report-file", required_argument,   0,   REPORT_FILE_OPTION },
 520   { "verbose",     no_argument,         0,   'v' },
 521
 522   /* Hidden. */
 523   { "trace",         optional_argument,   0,     'T' },
 524
 525   /* Output.  */
 526   { "defines",     optional_argument,   0,   'd' },
 527
 528   /* Operation modes.  */
 529   { "fixed-output-files", no_argument,  0,   'y' },
 530   { "yacc",               no_argument,  0,   'y' },
 531
 532   /* Parser.  */
 533   { "debug",          no_argument,               0,   't' },
 534   { "define",         required_argument,         0,   'D' },
 535   { "force-define",   required_argument,         0,   'F' },
 536   { "locations",      no_argument,               0, LOCATIONS_OPTION },
 537   { "no-lines",       no_argument,               0,   'l' },
 538   { "raw",            no_argument,               0,     0 },
 539   { "skeleton",       required_argument,         0,   'S' },
 540   { "language",       required_argument,         0,   'L' },
 541   { "token-table",    no_argument,               0,   'k' },
 542
 543   {0, 0, 0, 0}
 544 };
 545
 546 /* Under DOS, there is no difference on the case.  This can be
 547    troublesome when looking for `.tab' etc.  */
 548 #ifdef MSDOS
 549 # define AS_FILE_NAME(File) (strlwr (File), (File))
 550 #else
 551 # define AS_FILE_NAME(File) (File)
 552 #endif
 553
 554 /* Build a location for the current command line argument. */
 555 static
 556 location
 557 command_line_location (void)
 558 {
 559   location res;
 560   /* "<command line>" is used in GCC's messages about -D. */
 561   boundary_set (&res.start, uniqstr_new ("<command line>"), optind, -1);
 562   res.end = res.start;
 563   return res;
 564 }
 565
 566
 567 void
 568 getargs (int argc, char *argv[])
 569 {
 570   int c;
 571
 572   while ((c = getopt_long (argc, argv, short_options, long_options, NULL))
 573          != -1)
 574     switch (c)
 575       {
 576         /* ASCII Sorting for short options (i.e., upper case then
 577            lower case), and then long-only options.  */
 578
 579       case 0:
 580         /* Certain long options cause getopt_long to return 0.  */
 581         break;
 582
 583       case 'D': /* -DNAME[=VALUE]. */
 584       case 'F': /* -FNAME[=VALUE]. */
 585         {
 586           char* name = optarg;
 587           char* value = strchr (optarg, '=');
 588           if (value)
 589             *value++ = 0;
 590           muscle_percent_define_insert (name, command_line_location (),
 591                                         value ? value : "",
 592                                         c == 'D' ? MUSCLE_PERCENT_DEFINE_D
 593                                                  : MUSCLE_PERCENT_DEFINE_F);
 594         }
 595         break;
 596
 597       case 'I':
 598         include = AS_FILE_NAME (optarg);
 599         break;
 600
 601       case 'L':
 602         language_argmatch (optarg, command_line_prio,
 603                            command_line_location ());
 604         break;
 605
 606       case 'S':
 607         skeleton_arg (AS_FILE_NAME (optarg), command_line_prio,
 608                       command_line_location ());
 609         break;
 610
 611       case 'T':
 612         FLAGS_ARGMATCH (trace, optarg, trace_all);
 613         break;
 614
 615       case 'V':
 616         version ();
 617         exit (EXIT_SUCCESS);
 618
 619       case 'W':
 620         FLAGS_ARGMATCH (warnings, optarg, Wall);
 621         break;
 622
 623       case 'b':
 624         spec_file_prefix = AS_FILE_NAME (optarg);
 625         break;
 626
 627       case 'd':
 628         /* Here, the -d and --defines options are differentiated.  */
 629         defines_flag = true;
 630         if (optarg)
 631           {
 632             free (spec_defines_file);
 633             spec_defines_file = xstrdup (AS_FILE_NAME (optarg));
 634           }
 635         break;
 636
 637       case 'g':
 638         graph_flag = true;
 639         if (optarg)
 640           {
 641             free (spec_graph_file);
 642             spec_graph_file = xstrdup (AS_FILE_NAME (optarg));
 643           }
 644         break;
 645
 646       case 'h':
 647         usage (EXIT_SUCCESS);
 648
 649       case 'k':
 650         token_table_flag = true;
 651         break;
 652
 653       case 'l':
 654         no_lines_flag = true;
 655         break;
 656
 657       case 'o':
 658         spec_outfile = AS_FILE_NAME (optarg);
 659         break;
 660
 661       case 'p':
 662         spec_name_prefix = optarg;
 663         break;
 664
 665       case 'r':
 666         FLAGS_ARGMATCH (report, optarg, report_all);
 667         break;
 668
 669       case 't':
 670         muscle_percent_define_insert ("parse.trace",
 671                                       command_line_location (), "",
 672                                       MUSCLE_PERCENT_DEFINE_D);
 673         break;
 674
 675       case 'v':
 676         report_flag |= report_states;
 677         break;
 678
 679       case 'x':
 680         xml_flag = true;
 681         if (optarg)
 682           {
 683             free (spec_xml_file);
 684             spec_xml_file = xstrdup (AS_FILE_NAME (optarg));
 685           }
 686         break;
 687
 688       case 'y':
 689         warnings_flag |= Wyacc;
 690         errors_flag |= Wyacc;
 691         yacc_flag = true;
 692         break;
 693
 694       case LOCATIONS_OPTION:
 695         muscle_percent_define_ensure ("locations",
 696                                       command_line_location (), true);
 697         break;
 698
 699       case PRINT_LOCALEDIR_OPTION:
 700         printf ("%s\n", LOCALEDIR);
 701         exit (EXIT_SUCCESS);
 702
 703       case PRINT_DATADIR_OPTION:
 704         printf ("%s\n", pkgdatadir ());
 705         exit (EXIT_SUCCESS);
 706
 707       case REPORT_FILE_OPTION:
 708         free (spec_verbose_file);
 709         spec_verbose_file = xstrdup (AS_FILE_NAME (optarg));
 710         break;
 711
 712       default:
 713         usage (EXIT_FAILURE);
 714       }
 715
 716   if (argc - optind != 1)
 717     {
 718       if (argc - optind < 1)
 719         error (0, 0, _("%s: missing operand"), quotearg_colon (argv[argc - 1]));
 720       else
 721         error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
 722       usage (EXIT_FAILURE);
 723     }
 724
 725   current_file = grammar_file = uniqstr_new (argv[optind]);
 726   MUSCLE_INSERT_C_STRING ("file_name", grammar_file);
 727 }
 728
 729 void
 730 tr (char *s, char from, char to)
 731 {
 732   for (; *s; s++)
 733     if (*s == from)
 734       *s = to;
 735 }