contrib/less/ifile.c

   1 /*
   2  * Copyright (C) 1984-2008  Mark Nudelman
   3  *
   4  * You may distribute under the terms of either the GNU General Public
   5  * License or the Less License, as specified in the README file.
   6  *
   7  * For more information about less, or for information on how to
   8  * contact the author, see the README file.
   9  */
  10
  11
  12 /*
  13  * An IFILE represents an input file.
  14  *
  15  * It is actually a pointer to an ifile structure,
  16  * but is opaque outside this module.
  17  * Ifile structures are kept in a linked list in the order they
  18  * appear on the command line.
  19  * Any new file which does not already appear in the list is
  20  * inserted after the current file.
  21  */
  22
  23 #include "less.h"
  24
  25 extern IFILE    curr_ifile;
  26
  27 struct ifile {
  28         struct ifile *h_next;           /* Links for command line list */
  29         struct ifile *h_prev;
  30         char *h_filename;               /* Name of the file */
  31         void *h_filestate;              /* File state (used in ch.c) */
  32         int h_index;                    /* Index within command line list */
  33         int h_hold;                     /* Hold count */
  34         char h_opened;                  /* Has this ifile been opened? */
  35         struct scrpos h_scrpos;         /* Saved position within the file */
  36 };
  37
  38 /*
  39  * Convert an IFILE (external representation)
  40  * to a struct file (internal representation), and vice versa.
  41  */
  42 #define int_ifile(h)    ((struct ifile *)(h))
  43 #define ext_ifile(h)    ((IFILE)(h))
  44
  45 /*
  46  * Anchor for linked list.
  47  */
  48 static struct ifile anchor = { &anchor, &anchor, NULL, NULL, 0, 0, '\0',
  49                                 { NULL_POSITION, 0 } };
  50 static int ifiles = 0;
  51
  52         static void
  53 incr_index(p, incr)
  54         register struct ifile *p;
  55         int incr;
  56 {
  57         for (;  p != &anchor;  p = p->h_next)
  58                 p->h_index += incr;
  59 }
  60
  61 /*
  62  * Link an ifile into the ifile list.
  63  */
  64         static void
  65 link_ifile(p, prev)
  66         struct ifile *p;
  67         struct ifile *prev;
  68 {
  69         /*
  70          * Link into list.
  71          */
  72         if (prev == NULL)
  73                 prev = &anchor;
  74         p->h_next = prev->h_next;
  75         p->h_prev = prev;
  76         prev->h_next->h_prev = p;
  77         prev->h_next = p;
  78         /*
  79          * Calculate index for the new one,
  80          * and adjust the indexes for subsequent ifiles in the list.
  81          */
  82         p->h_index = prev->h_index + 1;
  83         incr_index(p->h_next, 1);
  84         ifiles++;
  85 }
  86
  87 /*
  88  * Unlink an ifile from the ifile list.
  89  */
  90         static void
  91 unlink_ifile(p)
  92         struct ifile *p;
  93 {
  94         p->h_next->h_prev = p->h_prev;
  95         p->h_prev->h_next = p->h_next;
  96         incr_index(p->h_next, -1);
  97         ifiles--;
  98 }
  99
 100 /*
 101  * Allocate a new ifile structure and stick a filename in it.
 102  * It should go after "prev" in the list
 103  * (or at the beginning of the list if "prev" is NULL).
 104  * Return a pointer to the new ifile structure.
 105  */
 106         static struct ifile *
 107 new_ifile(filename, prev)
 108         char *filename;
 109         struct ifile *prev;
 110 {
 111         register struct ifile *p;
 112
 113         /*
 114          * Allocate and initialize structure.
 115          */
 116         p = (struct ifile *) ecalloc(1, sizeof(struct ifile));
 117         p->h_filename = save(filename);
 118         p->h_scrpos.pos = NULL_POSITION;
 119         p->h_opened = 0;
 120         p->h_hold = 0;
 121         p->h_filestate = NULL;
 122         link_ifile(p, prev);
 123         return (p);
 124 }
 125
 126 /*
 127  * Delete an existing ifile structure.
 128  */
 129         public void
 130 del_ifile(h)
 131         IFILE h;
 132 {
 133         register struct ifile *p;
 134
 135         if (h == NULL_IFILE)
 136                 return;
 137         /*
 138          * If the ifile we're deleting is the currently open ifile,
 139          * move off it.
 140          */
 141         unmark(h);
 142         if (h == curr_ifile)
 143                 curr_ifile = getoff_ifile(curr_ifile);
 144         p = int_ifile(h);
 145         unlink_ifile(p);
 146         free(p->h_filename);
 147         free(p);
 148 }
 149
 150 /*
 151  * Get the ifile after a given one in the list.
 152  */
 153         public IFILE
 154 next_ifile(h)
 155         IFILE h;
 156 {
 157         register struct ifile *p;
 158
 159         p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
 160         if (p->h_next == &anchor)
 161                 return (NULL_IFILE);
 162         return (ext_ifile(p->h_next));
 163 }
 164
 165 /*
 166  * Get the ifile before a given one in the list.
 167  */
 168         public IFILE
 169 prev_ifile(h)
 170         IFILE h;
 171 {
 172         register struct ifile *p;
 173
 174         p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
 175         if (p->h_prev == &anchor)
 176                 return (NULL_IFILE);
 177         return (ext_ifile(p->h_prev));
 178 }
 179
 180 /*
 181  * Return a different ifile from the given one.
 182  */
 183         public IFILE
 184 getoff_ifile(ifile)
 185         IFILE ifile;
 186 {
 187         IFILE newifile;
 188
 189         if ((newifile = prev_ifile(ifile)) != NULL_IFILE)
 190                 return (newifile);
 191         if ((newifile = next_ifile(ifile)) != NULL_IFILE)
 192                 return (newifile);
 193         return (NULL_IFILE);
 194 }
 195
 196 /*
 197  * Return the number of ifiles.
 198  */
 199         public int
 200 nifile()
 201 {
 202         return (ifiles);
 203 }
 204
 205 /*
 206  * Find an ifile structure, given a filename.
 207  */
 208         static struct ifile *
 209 find_ifile(filename)
 210         char *filename;
 211 {
 212         register struct ifile *p;
 213
 214         for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
 215                 if (strcmp(filename, p->h_filename) == 0)
 216                         return (p);
 217         return (NULL);
 218 }
 219
 220 /*
 221  * Get the ifile associated with a filename.
 222  * If the filename has not been seen before,
 223  * insert the new ifile after "prev" in the list.
 224  */
 225         public IFILE
 226 get_ifile(filename, prev)
 227         char *filename;
 228         IFILE prev;
 229 {
 230         register struct ifile *p;
 231
 232         if ((p = find_ifile(filename)) == NULL)
 233                 p = new_ifile(filename, int_ifile(prev));
 234         return (ext_ifile(p));
 235 }
 236
 237 /*
 238  * Get the filename associated with a ifile.
 239  */
 240         public char *
 241 get_filename(ifile)
 242         IFILE ifile;
 243 {
 244         if (ifile == NULL)
 245                 return (NULL);
 246         return (int_ifile(ifile)->h_filename);
 247 }
 248
 249 /*
 250  * Get the index of the file associated with a ifile.
 251  */
 252         public int
 253 get_index(ifile)
 254         IFILE ifile;
 255 {
 256         return (int_ifile(ifile)->h_index);
 257 }
 258
 259 /*
 260  * Save the file position to be associated with a given file.
 261  */
 262         public void
 263 store_pos(ifile, scrpos)
 264         IFILE ifile;
 265         struct scrpos *scrpos;
 266 {
 267         int_ifile(ifile)->h_scrpos = *scrpos;
 268 }
 269
 270 /*
 271  * Recall the file position associated with a file.
 272  * If no position has been associated with the file, return NULL_POSITION.
 273  */
 274         public void
 275 get_pos(ifile, scrpos)
 276         IFILE ifile;
 277         struct scrpos *scrpos;
 278 {
 279         *scrpos = int_ifile(ifile)->h_scrpos;
 280 }
 281
 282 /*
 283  * Mark the ifile as "opened".
 284  */
 285         public void
 286 set_open(ifile)
 287         IFILE ifile;
 288 {
 289         int_ifile(ifile)->h_opened = 1;
 290 }
 291
 292 /*
 293  * Return whether the ifile has been opened previously.
 294  */
 295         public int
 296 opened(ifile)
 297         IFILE ifile;
 298 {
 299         return (int_ifile(ifile)->h_opened);
 300 }
 301
 302         public void
 303 hold_ifile(ifile, incr)
 304         IFILE ifile;
 305         int incr;
 306 {
 307         int_ifile(ifile)->h_hold += incr;
 308 }
 309
 310         public int
 311 held_ifile(ifile)
 312         IFILE ifile;
 313 {
 314         return (int_ifile(ifile)->h_hold);
 315 }
 316
 317         public void *
 318 get_filestate(ifile)
 319         IFILE ifile;
 320 {
 321         return (int_ifile(ifile)->h_filestate);
 322 }
 323
 324         public void
 325 set_filestate(ifile, filestate)
 326         IFILE ifile;
 327         void *filestate;
 328 {
 329         int_ifile(ifile)->h_filestate = filestate;
 330 }
 331
 332 #if 0
 333         public void
 334 if_dump()
 335 {
 336         register struct ifile *p;
 337
 338         for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
 339         {
 340                 printf("%x: %d. <%s> pos %d,%x\n",
 341                         p, p->h_index, p->h_filename,
 342                         p->h_scrpos.ln, p->h_scrpos.pos);
 343                 ch_dump(p->h_filestate);
 344         }
 345 }
 346 #endif