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

   1 /* -*-c-*-
   2  *
   3  * $Id: scan.c,v 1.2 1999/07/26 23:24:33 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 1.2  1999/07/26 23:24:33  mdw
  33  * Complete rewrite.  Allow a list of character sources to enable changes
  34  * during parsing of syntactic constructs.
  35  *
  36  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  37  * Initial revision.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 #include "config.h"
  44
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48
  49 #include <mLib/dstr.h>
  50 #include <mLib/sub.h>
  51
  52 #include "scan.h"
  53
  54 /*----- File scanner source -----------------------------------------------*/
  55
  56 /* --- File scanner block --- */
  57
  58 typedef struct fscan {
  59   scansrc ss;
  60   FILE *fp;
  61   unsigned f;
  62 } fscan;
  63
  64 /* --- @scan@ --- */
  65
  66 static int fscan_scan(scansrc *ss)
  67 {
  68   fscan *fs = (fscan *)ss;
  69   int ch = getc(fs->fp);
  70   if (ch == '\n')
  71     fs->ss.line++;
  72   return (ch);
  73 }
  74
  75 /* --- @destroy@ --- */
  76
  77 static void fscan_destroy(scansrc *ss)
  78 {
  79   fscan *fs = (fscan *)ss;
  80   if (!(fs->f & SCF_NOCLOSE))
  81     fclose(fs->fp);
  82   if (fs->f & SCF_FREENAME)
  83     free(fs->ss.src);
  84   DESTROY(fs);
  85 }
  86
  87 /* --- File scanner operations --- */
  88
  89 static scansrc_ops fscan_ops = { fscan_scan, fscan_destroy };
  90
  91 /* --- @scan_file@ --- *
  92  *
  93  * Arguments:   @FILE *fp@ = pointer to file descriptor
  94  *              @char *name@ = pointer to source file name
  95  *              @unsigned f@ = flags
  96  *
  97  * Returns:     A scanner source.
  98  *
  99  * Use:         Creates a new scanner source for reading from a file.
 100  */
 101
 102 scansrc *scan_file(FILE *fp, char *name, unsigned f)
 103 {
 104   fscan *fs = CREATE(fs);
 105   fs->ss.ops = &fscan_ops;
 106   fs->ss.src = name;
 107   fs->ss.line = 1;
 108   fs->fp = fp;
 109   fs->f = f;
 110   return (&fs->ss);
 111 }
 112
 113 /*---- Argv scanner source ------------------------------------------------*/
 114
 115 /* --- Argv scanner block --- */
 116
 117 typedef struct avscan {
 118   scansrc ss;
 119   char **av;
 120   char *p;
 121 } avscan;
 122
 123 /* --- @scan@ --- */
 124
 125 static int avscan_scan(scansrc *ss)
 126 {
 127   avscan *as = (avscan *)ss;
 128   int ch;
 129   if (!as->p)
 130     ch = EOF;
 131   else if ((ch = *as->p++) == 0) {
 132     as->ss.line++;
 133     as->p = *as->av++;
 134     ch = '\n';
 135   }
 136   return (ch);
 137 }
 138
 139 /* --- @destroy@ --- */
 140
 141 static void avscan_destroy(scansrc *ss)
 142 {
 143   avscan *as = (avscan *)ss;
 144   DESTROY(as);
 145 }
 146
 147 /* --- Argv scanner operations --- */
 148
 149 static scansrc_ops avscan_ops = { avscan_scan, avscan_destroy };
 150
 151 /* --- @scan_argv@ --- *
 152  *
 153  * Arguments:   @char **av@ = pointer to argument array (null terminated)
 154  *
 155  * Returns:     A scanner source.
 156  *
 157  * Use:         Creates a new scanner source for reading from an @argv@
 158  *              array.
 159  */
 160
 161 scansrc *scan_argv(char **av)
 162 {
 163   avscan *as = CREATE(avscan);
 164   as->ss.ops = &avscan_ops;
 165   as->ss.src = "<argv>";
 166   as->ss.line = 1;
 167   as->p = *av++;
 168   as->av = av;
 169   return (&as->ss);
 170 }
 171
 172 /*----- End-of-file sentinel block ----------------------------------------*/
 173
 174 /* --- @scan@ --- */
 175
 176 static int eof_scan(scansrc *ss)
 177 {
 178   return (EOF);
 179 }
 180
 181 /* --- @destroy@ --- */
 182
 183 static void eof_destroy(scansrc *ss)
 184 {
 185   ;
 186 }
 187
 188 /* --- Eof scanner operations --- */
 189
 190 static scansrc_ops eof_ops = { eof_scan, eof_destroy };
 191
 192 /* --- The end of file marker --- */
 193
 194 static scansrc scan_eof = { &scan_eof, &eof_ops, "<eof>", 0, EOF };
 195
 196 /*----- General scanner handling ------------------------------------------*/
 197
 198 /* --- @scan@ --- *
 199  *
 200  * Arguments:   @scanner *sc@ = pointer to main scanner context
 201  *
 202  * Returns:     Character read, or end-of-file.
 203  *
 204  * Use:         Scans a character from a source of characters.
 205  */
 206
 207 int scan(scanner *sc)
 208 {
 209   int ch;
 210   if (sc->head->pushback != EOF) {
 211     ch = sc->head->pushback;
 212     sc->head->pushback = EOF;
 213   } else {
 214     scansrc *ss = sc->head;
 215     if (ss == &scan_eof)
 216       ch = EOF;
 217     else if ((ch = ss->ops->scan(ss)) == EOF) {
 218       sc->head = ss->next;
 219       if (sc->head == &scan_eof)
 220         sc->tail = &sc->head;
 221       ss->ops->destroy(ss);
 222       ch = '\n';
 223     }
 224   }
 225   return (ch);
 226 }
 227
 228 /* --- @unscan@ --- *
 229  *
 230  * Arguments:   @scanner *sc@ = pointer to main scanner context
 231  *              @int ch@ = character to unscan
 232  *
 233  * Returns:     ---
 234  *
 235  * Use:         Scans a character from a source of characters.
 236  */
 237
 238 void unscan(scanner *sc, int ch)
 239 {
 240   sc->head->pushback = ch;
 241 }
 242
 243 /* --- @scan_push@ --- *
 244  *
 245  * Arguments:   @scanner *sc@ = pointer to main scanner context
 246  *              @scansrc *ss@ = souorce to push
 247  *
 248  * Returns:     ---
 249  *
 250  * Use:         Pushes a scanner source onto the front of the queue.
 251  */
 252
 253 void scan_push(scanner *sc, scansrc *ss)
 254 {
 255   ss->next = sc->head;
 256   if (sc->head == &scan_eof)
 257     sc->tail = &ss->next;
 258   sc->head = ss;
 259   ss->pushback = EOF;
 260   ss->tok = 0;
 261   ss->t = 0;
 262 }
 263
 264 /* --- @scan_add@ --- *
 265  *
 266  * Arguments:   @scanner *sc@ = pointer to main scanner context
 267  *              @scansrc *ss@ = souorce to push
 268  *
 269  * Returns:     ---
 270  *
 271  * Use:         Adds a scanner source onto the end of the queue.
 272  */
 273
 274 void scan_add(scanner *sc, scansrc *ss)
 275 {
 276   ss->next = &scan_eof;
 277   *sc->tail = ss;
 278   sc->tail = &ss->next;
 279   ss->pushback = EOF;
 280   ss->tok = 0;
 281   ss->t = 0;
 282 }
 283
 284 /* --- @scan_create@ --- *
 285  *
 286  * Arguments:   @scanner *sc@ = scanner context to initialize
 287  *
 288  * Returns:     ---
 289  *
 290  * Use:         Initializes a scanner block ready for use.
 291  */
 292
 293 void scan_create(scanner *sc)
 294 {
 295   sc->head = &scan_eof;
 296   sc->tail = &sc->head;
 297   dstr_create(&sc->d);
 298 }
 299
 300 /* --- @scan_destroy@ --- *
 301  *
 302  * Arguments:   @scanner *sc@ = pointer to scanner context
 303  *
 304  * Returns:     ---
 305  *
 306  * Use:         Destroys a scanner and all the sources attached to it.
 307  */
 308
 309 void scan_destroy(scanner *sc)
 310 {
 311   scansrc *ss = sc->head;
 312   while (ss != &scan_eof) {
 313     scansrc *sss = ss;
 314     ss = ss->next;
 315     if (sss->tok)
 316       free(sss->tok);
 317     sss->ops->destroy(sss);
 318   }
 319   dstr_destroy(&sc->d);
 320   if (scan_eof.tok)
 321     free(scan_eof.tok);
 322   scan_eof.tok = 0;
 323   sc->head = &scan_eof;
 324   sc->tail = &sc->head;
 325 }
 326
 327 /*----- That's all, folks -------------------------------------------------*/