mdw@git.distorted.org.uk Git - fwd/blob - scan.c

   1 /* -*-c-*-
   2  *
   3  * $Id: scan.c,v 1.6 2002/02/22 23:44:16 mdw Exp $
   4  *
   5  * Character scanners
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: scan.c,v $
  32  * Revision 1.6  2002/02/22 23:44:16  mdw
  33  * Miscellaneous tidying up, to make this code independent of `fw'.  It
  34  * might end up in a library somewhere.
  35  *
  36  * Revision 1.5  2002/01/30 09:29:34  mdw
  37  * Initialize scanner properly.
  38  *
  39  * Revision 1.4  2001/02/03 20:30:03  mdw
  40  * Support re-reading config files on SIGHUP.
  41  *
  42  * Revision 1.3  2000/08/01 17:58:10  mdw
  43  * Fix subtleties with <ctype.h> functions.
  44  *
  45  * Revision 1.2  1999/07/26 23:24:33  mdw
  46  * Complete rewrite.  Allow a list of character sources to enable changes
  47  * during parsing of syntactic constructs.
  48  *
  49  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  50  * Initial revision.
  51  *
  52  */
  53
  54 /*----- Header files ------------------------------------------------------*/
  55
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59
  60 #include <mLib/dstr.h>
  61 #include <mLib/sub.h>
  62
  63 #include "scan.h"
  64
  65 /*----- File scanner source -----------------------------------------------*/
  66
  67 /* --- File scanner block --- */
  68
  69 typedef struct fscan {
  70   scansrc ss;
  71   FILE *fp;
  72   unsigned f;
  73 } fscan;
  74
  75 /* --- @scan@ --- */
  76
  77 static int fscan_scan(scansrc *ss)
  78 {
  79   fscan *fs = (fscan *)ss;
  80   int ch = getc(fs->fp);
  81   if (ch == '\n')
  82     fs->ss.line++;
  83   return (ch);
  84 }
  85
  86 /* --- @destroy@ --- */
  87
  88 static void fscan_destroy(scansrc *ss)
  89 {
  90   fscan *fs = (fscan *)ss;
  91   if (!(fs->f & SCF_NOCLOSE))
  92     fclose(fs->fp);
  93   xfree(fs->ss.src);
  94   DESTROY(fs);
  95 }
  96
  97 /* --- File scanner operations --- */
  98
  99 static scansrc_ops fscan_ops = { fscan_scan, fscan_destroy };
 100
 101 /* --- @scan_file@ --- *
 102  *
 103  * Arguments:   @FILE *fp@ = pointer to file descriptor
 104  *              @const char *name@ = pointer to source file name
 105  *              @unsigned f@ = flags
 106  *
 107  * Returns:     A scanner source.
 108  *
 109  * Use:         Creates a new scanner source for reading from a file.
 110  */
 111
 112 scansrc *scan_file(FILE *fp, const char *name, unsigned f)
 113 {
 114   fscan *fs = CREATE(fscan);
 115   fs->ss.ops = &fscan_ops;
 116   fs->ss.src = xstrdup(name);
 117   fs->ss.line = 1;
 118   fs->fp = fp;
 119   fs->f = f;
 120   return (&fs->ss);
 121 }
 122
 123 /*---- Argv scanner source ------------------------------------------------*/
 124
 125 /* --- Argv scanner block --- */
 126
 127 typedef struct avscan {
 128   scansrc ss;
 129   char **av;
 130   char *p;
 131 } avscan;
 132
 133 /* --- @scan@ --- */
 134
 135 static int avscan_scan(scansrc *ss)
 136 {
 137   avscan *as = (avscan *)ss;
 138   int ch;
 139   if (!as->p)
 140     ch = EOF;
 141   else if ((ch = (unsigned char)*as->p++) == 0) {
 142     as->ss.line++;
 143     as->p = *as->av++;
 144     ch = '\n';
 145   }
 146   return (ch);
 147 }
 148
 149 /* --- @destroy@ --- */
 150
 151 static void avscan_destroy(scansrc *ss)
 152 {
 153   avscan *as = (avscan *)ss;
 154   DESTROY(as);
 155 }
 156
 157 /* --- Argv scanner operations --- */
 158
 159 static scansrc_ops avscan_ops = { avscan_scan, avscan_destroy };
 160
 161 /* --- @scan_argv@ --- *
 162  *
 163  * Arguments:   @char **av@ = pointer to argument array (null terminated)
 164  *
 165  * Returns:     A scanner source.
 166  *
 167  * Use:         Creates a new scanner source for reading from an @argv@
 168  *              array.
 169  */
 170
 171 scansrc *scan_argv(char **av)
 172 {
 173   avscan *as = CREATE(avscan);
 174   as->ss.ops = &avscan_ops;
 175   as->ss.src = "<argv>";
 176   as->ss.line = 1;
 177   as->p = *av++;
 178   as->av = av;
 179   return (&as->ss);
 180 }
 181
 182 /*----- End-of-file sentinel block ----------------------------------------*/
 183
 184 /* --- @scan@ --- */
 185
 186 static int eof_scan(scansrc *ss)
 187 {
 188   return (EOF);
 189 }
 190
 191 /* --- @destroy@ --- */
 192
 193 static void eof_destroy(scansrc *ss)
 194 {
 195   ;
 196 }
 197
 198 /* --- Eof scanner operations --- */
 199
 200 static scansrc_ops eof_ops = { eof_scan, eof_destroy };
 201
 202 /* --- The end of file marker --- */
 203
 204 static scansrc scan_eof = { &scan_eof, &eof_ops, "<eof>", 0, DSTR_INIT };
 205
 206 /*----- General scanner handling ------------------------------------------*/
 207
 208 /* --- @scan@ --- *
 209  *
 210  * Arguments:   @scanner *sc@ = pointer to main scanner context
 211  *
 212  * Returns:     Character read, or end-of-file.
 213  *
 214  * Use:         Scans a character from a source of characters.
 215  */
 216
 217 int scan(scanner *sc)
 218 {
 219   int ch;
 220   if (sc->head->pushback.len)
 221     ch = sc->head->pushback.buf[--sc->head->pushback.len];
 222   else {
 223     scansrc *ss = sc->head;
 224     if (ss == &scan_eof)
 225       ch = EOF;
 226     else if ((ch = ss->ops->scan(ss)) == EOF) {
 227       sc->head = ss->next;
 228       if (sc->head == &scan_eof)
 229         sc->tail = &sc->head;
 230       ss->ops->destroy(ss);
 231       ch = '\n';
 232     }
 233   }
 234   return (ch);
 235 }
 236
 237 /* --- @unscan@ --- *
 238  *
 239  * Arguments:   @scanner *sc@ = pointer to main scanner context
 240  *              @int ch@ = character to unscan
 241  *
 242  * Returns:     ---
 243  *
 244  * Use:         Scans a character from a source of characters.
 245  */
 246
 247 void unscan(scanner *sc, int ch)
 248 {
 249   DPUTC(&sc->head->pushback, ch);
 250 }
 251
 252 /* --- @scan_push@ --- *
 253  *
 254  * Arguments:   @scanner *sc@ = pointer to main scanner context
 255  *              @scansrc *ss@ = souorce to push
 256  *
 257  * Returns:     ---
 258  *
 259  * Use:         Pushes a scanner source onto the front of the queue.
 260  */
 261
 262 void scan_push(scanner *sc, scansrc *ss)
 263 {
 264   ss->next = sc->head;
 265   if (sc->head == &scan_eof)
 266     sc->tail = &ss->next;
 267   sc->head = ss;
 268   dstr_create(&ss->pushback);
 269   ss->tok = 0;
 270   ss->t = 0;
 271 }
 272
 273 /* --- @scan_add@ --- *
 274  *
 275  * Arguments:   @scanner *sc@ = pointer to main scanner context
 276  *              @scansrc *ss@ = souorce to push
 277  *
 278  * Returns:     ---
 279  *
 280  * Use:         Adds a scanner source onto the end of the queue.
 281  */
 282
 283 void scan_add(scanner *sc, scansrc *ss)
 284 {
 285   ss->next = &scan_eof;
 286   *sc->tail = ss;
 287   sc->tail = &ss->next;
 288   dstr_create(&ss->pushback);
 289   ss->tok = 0;
 290   ss->t = 0;
 291 }
 292
 293 /* --- @scan_create@ --- *
 294  *
 295  * Arguments:   @scanner *sc@ = scanner context to initialize
 296  *
 297  * Returns:     ---
 298  *
 299  * Use:         Initializes a scanner block ready for use.
 300  */
 301
 302 void scan_create(scanner *sc)
 303 {
 304   sc->head = &scan_eof;
 305   sc->tail = &sc->head;
 306   dstr_create(&sc->d);
 307   sc->wbegin = sc->wcont = 0;
 308 }
 309
 310 /* --- @scan_destroy@ --- *
 311  *
 312  * Arguments:   @scanner *sc@ = pointer to scanner context
 313  *
 314  * Returns:     ---
 315  *
 316  * Use:         Destroys a scanner and all the sources attached to it.
 317  */
 318
 319 void scan_destroy(scanner *sc)
 320 {
 321   scansrc *ss = sc->head;
 322   while (ss != &scan_eof) {
 323     scansrc *sss = ss;
 324     ss = ss->next;
 325     if (sss->tok)
 326       xfree(sss->tok);
 327     dstr_destroy(&sss->pushback);
 328     sss->ops->destroy(sss);
 329   }
 330   dstr_destroy(&sc->d);
 331   if (scan_eof.tok)
 332     xfree(scan_eof.tok);
 333   scan_eof.tok = 0;
 334   sc->head = &scan_eof;
 335   sc->tail = &sc->head;
 336 }
 337
 338 /*----- That's all, folks -------------------------------------------------*/