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

   1 /* -*-c-*-
   2  *
   3  * $Id: scan.c,v 1.3 2000/08/01 17:58:10 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 1.3  2000/08/01 17:58:10  mdw
  33  * Fix subtleties with <ctype.h> functions.
  34  *
  35  * Revision 1.2  1999/07/26 23:24:33  mdw
  36  * Complete rewrite.  Allow a list of character sources to enable changes
  37  * during parsing of syntactic constructs.
  38  *
  39  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  40  * Initial revision.
  41  *
  42  */
  43
  44 /*----- Header files ------------------------------------------------------*/
  45
  46 #include "config.h"
  47
  48 #include <stdio.h>
  49 #include <stdlib.h>
  50 #include <string.h>
  51
  52 #include <mLib/dstr.h>
  53 #include <mLib/sub.h>
  54
  55 #include "scan.h"
  56
  57 /*----- File scanner source -----------------------------------------------*/
  58
  59 /* --- File scanner block --- */
  60
  61 typedef struct fscan {
  62   scansrc ss;
  63   FILE *fp;
  64   unsigned f;
  65 } fscan;
  66
  67 /* --- @scan@ --- */
  68
  69 static int fscan_scan(scansrc *ss)
  70 {
  71   fscan *fs = (fscan *)ss;
  72   int ch = getc(fs->fp);
  73   if (ch == '\n')
  74     fs->ss.line++;
  75   return (ch);
  76 }
  77
  78 /* --- @destroy@ --- */
  79
  80 static void fscan_destroy(scansrc *ss)
  81 {
  82   fscan *fs = (fscan *)ss;
  83   if (!(fs->f & SCF_NOCLOSE))
  84     fclose(fs->fp);
  85   if (fs->f & SCF_FREENAME)
  86     free(fs->ss.src);
  87   DESTROY(fs);
  88 }
  89
  90 /* --- File scanner operations --- */
  91
  92 static scansrc_ops fscan_ops = { fscan_scan, fscan_destroy };
  93
  94 /* --- @scan_file@ --- *
  95  *
  96  * Arguments:   @FILE *fp@ = pointer to file descriptor
  97  *              @char *name@ = pointer to source file name
  98  *              @unsigned f@ = flags
  99  *
 100  * Returns:     A scanner source.
 101  *
 102  * Use:         Creates a new scanner source for reading from a file.
 103  */
 104
 105 scansrc *scan_file(FILE *fp, char *name, unsigned f)
 106 {
 107   fscan *fs = CREATE(fs);
 108   fs->ss.ops = &fscan_ops;
 109   fs->ss.src = name;
 110   fs->ss.line = 1;
 111   fs->fp = fp;
 112   fs->f = f;
 113   return (&fs->ss);
 114 }
 115
 116 /*---- Argv scanner source ------------------------------------------------*/
 117
 118 /* --- Argv scanner block --- */
 119
 120 typedef struct avscan {
 121   scansrc ss;
 122   char **av;
 123   char *p;
 124 } avscan;
 125
 126 /* --- @scan@ --- */
 127
 128 static int avscan_scan(scansrc *ss)
 129 {
 130   avscan *as = (avscan *)ss;
 131   int ch;
 132   if (!as->p)
 133     ch = EOF;
 134   else if ((ch = (unsigned char)*as->p++) == 0) {
 135     as->ss.line++;
 136     as->p = *as->av++;
 137     ch = '\n';
 138   }
 139   return (ch);
 140 }
 141
 142 /* --- @destroy@ --- */
 143
 144 static void avscan_destroy(scansrc *ss)
 145 {
 146   avscan *as = (avscan *)ss;
 147   DESTROY(as);
 148 }
 149
 150 /* --- Argv scanner operations --- */
 151
 152 static scansrc_ops avscan_ops = { avscan_scan, avscan_destroy };
 153
 154 /* --- @scan_argv@ --- *
 155  *
 156  * Arguments:   @char **av@ = pointer to argument array (null terminated)
 157  *
 158  * Returns:     A scanner source.
 159  *
 160  * Use:         Creates a new scanner source for reading from an @argv@
 161  *              array.
 162  */
 163
 164 scansrc *scan_argv(char **av)
 165 {
 166   avscan *as = CREATE(avscan);
 167   as->ss.ops = &avscan_ops;
 168   as->ss.src = "<argv>";
 169   as->ss.line = 1;
 170   as->p = *av++;
 171   as->av = av;
 172   return (&as->ss);
 173 }
 174
 175 /*----- End-of-file sentinel block ----------------------------------------*/
 176
 177 /* --- @scan@ --- */
 178
 179 static int eof_scan(scansrc *ss)
 180 {
 181   return (EOF);
 182 }
 183
 184 /* --- @destroy@ --- */
 185
 186 static void eof_destroy(scansrc *ss)
 187 {
 188   ;
 189 }
 190
 191 /* --- Eof scanner operations --- */
 192
 193 static scansrc_ops eof_ops = { eof_scan, eof_destroy };
 194
 195 /* --- The end of file marker --- */
 196
 197 static scansrc scan_eof = { &scan_eof, &eof_ops, "<eof>", 0, EOF };
 198
 199 /*----- General scanner handling ------------------------------------------*/
 200
 201 /* --- @scan@ --- *
 202  *
 203  * Arguments:   @scanner *sc@ = pointer to main scanner context
 204  *
 205  * Returns:     Character read, or end-of-file.
 206  *
 207  * Use:         Scans a character from a source of characters.
 208  */
 209
 210 int scan(scanner *sc)
 211 {
 212   int ch;
 213   if (sc->head->pushback != EOF) {
 214     ch = sc->head->pushback;
 215     sc->head->pushback = EOF;
 216   } else {
 217     scansrc *ss = sc->head;
 218     if (ss == &scan_eof)
 219       ch = EOF;
 220     else if ((ch = ss->ops->scan(ss)) == EOF) {
 221       sc->head = ss->next;
 222       if (sc->head == &scan_eof)
 223         sc->tail = &sc->head;
 224       ss->ops->destroy(ss);
 225       ch = '\n';
 226     }
 227   }
 228   return (ch);
 229 }
 230
 231 /* --- @unscan@ --- *
 232  *
 233  * Arguments:   @scanner *sc@ = pointer to main scanner context
 234  *              @int ch@ = character to unscan
 235  *
 236  * Returns:     ---
 237  *
 238  * Use:         Scans a character from a source of characters.
 239  */
 240
 241 void unscan(scanner *sc, int ch)
 242 {
 243   sc->head->pushback = ch;
 244 }
 245
 246 /* --- @scan_push@ --- *
 247  *
 248  * Arguments:   @scanner *sc@ = pointer to main scanner context
 249  *              @scansrc *ss@ = souorce to push
 250  *
 251  * Returns:     ---
 252  *
 253  * Use:         Pushes a scanner source onto the front of the queue.
 254  */
 255
 256 void scan_push(scanner *sc, scansrc *ss)
 257 {
 258   ss->next = sc->head;
 259   if (sc->head == &scan_eof)
 260     sc->tail = &ss->next;
 261   sc->head = ss;
 262   ss->pushback = EOF;
 263   ss->tok = 0;
 264   ss->t = 0;
 265 }
 266
 267 /* --- @scan_add@ --- *
 268  *
 269  * Arguments:   @scanner *sc@ = pointer to main scanner context
 270  *              @scansrc *ss@ = souorce to push
 271  *
 272  * Returns:     ---
 273  *
 274  * Use:         Adds a scanner source onto the end of the queue.
 275  */
 276
 277 void scan_add(scanner *sc, scansrc *ss)
 278 {
 279   ss->next = &scan_eof;
 280   *sc->tail = ss;
 281   sc->tail = &ss->next;
 282   ss->pushback = EOF;
 283   ss->tok = 0;
 284   ss->t = 0;
 285 }
 286
 287 /* --- @scan_create@ --- *
 288  *
 289  * Arguments:   @scanner *sc@ = scanner context to initialize
 290  *
 291  * Returns:     ---
 292  *
 293  * Use:         Initializes a scanner block ready for use.
 294  */
 295
 296 void scan_create(scanner *sc)
 297 {
 298   sc->head = &scan_eof;
 299   sc->tail = &sc->head;
 300   dstr_create(&sc->d);
 301 }
 302
 303 /* --- @scan_destroy@ --- *
 304  *
 305  * Arguments:   @scanner *sc@ = pointer to scanner context
 306  *
 307  * Returns:     ---
 308  *
 309  * Use:         Destroys a scanner and all the sources attached to it.
 310  */
 311
 312 void scan_destroy(scanner *sc)
 313 {
 314   scansrc *ss = sc->head;
 315   while (ss != &scan_eof) {
 316     scansrc *sss = ss;
 317     ss = ss->next;
 318     if (sss->tok)
 319       free(sss->tok);
 320     sss->ops->destroy(sss);
 321   }
 322   dstr_destroy(&sc->d);
 323   if (scan_eof.tok)
 324     free(scan_eof.tok);
 325   scan_eof.tok = 0;
 326   sc->head = &scan_eof;
 327   sc->tail = &sc->head;
 328 }
 329
 330 /*----- That's all, folks -------------------------------------------------*/