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ifile.c

/*
 * Copyright (C) 1984-2002  Mark Nudelman
 *
 * You may distribute under the terms of either the GNU General Public
 * License or the Less License, as specified in the README file.
 *
 * For more information about less, or for information on how to 
 * contact the author, see the README file.
 */


/*
 * An IFILE represents an input file.
 *
 * It is actually a pointer to an ifile structure,
 * but is opaque outside this module.
 * Ifile structures are kept in a linked list in the order they 
 * appear on the command line.
 * Any new file which does not already appear in the list is
 * inserted after the current file.
 */

#include "less.h"

extern IFILE      curr_ifile;

struct ifile {
      struct ifile *h_next;         /* Links for command line list */
      struct ifile *h_prev;
      char *h_filename;       /* Name of the file */
      void *h_filestate;            /* File state (used in ch.c) */
      int h_index;                  /* Index within command line list */
      int h_hold;             /* Hold count */
      char h_opened;                /* Has this ifile been opened? */
      struct scrpos h_scrpos;       /* Saved position within the file */
};

/*
 * Convert an IFILE (external representation)
 * to a struct file (internal representation), and vice versa.
 */
#define int_ifile(h)    ((struct ifile *)(h))
#define ext_ifile(h)    ((IFILE)(h))

/*
 * Anchor for linked list.
 */
static struct ifile anchor = { &anchor, &anchor, NULL, NULL, 0, 0, '\0',
                        { NULL_POSITION, 0 } };
static int ifiles = 0;

      static void
incr_index(p, incr)
      register struct ifile *p;
      int incr;
{
      for (;  p != &anchor;  p = p->h_next)
            p->h_index += incr;
}

/*
 * Link an ifile into the ifile list.
 */
      static void
link_ifile(p, prev)
      struct ifile *p;
      struct ifile *prev;
{
      /*
       * Link into list.
       */
      if (prev == NULL)
            prev = &anchor;
      p->h_next = prev->h_next;
      p->h_prev = prev;
      prev->h_next->h_prev = p;
      prev->h_next = p;
      /*
       * Calculate index for the new one,
       * and adjust the indexes for subsequent ifiles in the list.
       */
      p->h_index = prev->h_index + 1;
      incr_index(p->h_next, 1);
      ifiles++;
}
      
/*
 * Unlink an ifile from the ifile list.
 */
      static void
unlink_ifile(p)
      struct ifile *p;
{
      p->h_next->h_prev = p->h_prev;
      p->h_prev->h_next = p->h_next;
      incr_index(p->h_next, -1);
      ifiles--;
}

/*
 * Allocate a new ifile structure and stick a filename in it.
 * It should go after "prev" in the list
 * (or at the beginning of the list if "prev" is NULL).
 * Return a pointer to the new ifile structure.
 */
      static struct ifile *
new_ifile(filename, prev)
      char *filename;
      struct ifile *prev;
{
      register struct ifile *p;

      /*
       * Allocate and initialize structure.
       */
      p = (struct ifile *) ecalloc(1, sizeof(struct ifile));
      p->h_filename = save(filename);
      p->h_scrpos.pos = NULL_POSITION;
      p->h_opened = 0;
      p->h_hold = 0;
      p->h_filestate = NULL;
      link_ifile(p, prev);
      return (p);
}

/*
 * Delete an existing ifile structure.
 */
      public void
del_ifile(h)
      IFILE h;
{
      register struct ifile *p;

      if (h == NULL_IFILE)
            return;
      /*
       * If the ifile we're deleting is the currently open ifile,
       * move off it.
       */
      unmark(h);
      if (h == curr_ifile)
            curr_ifile = getoff_ifile(curr_ifile);
      p = int_ifile(h);
      unlink_ifile(p);
      free(p->h_filename);
      free(p);
}

/*
 * Get the ifile after a given one in the list.
 */
      public IFILE
next_ifile(h)
      IFILE h;
{
      register struct ifile *p;

      p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
      if (p->h_next == &anchor)
            return (NULL_IFILE);
      return (ext_ifile(p->h_next));
}

/*
 * Get the ifile before a given one in the list.
 */
      public IFILE
prev_ifile(h)
      IFILE h;
{
      register struct ifile *p;

      p = (h == NULL_IFILE) ? &anchor : int_ifile(h);
      if (p->h_prev == &anchor)
            return (NULL_IFILE);
      return (ext_ifile(p->h_prev));
}

/*
 * Return a different ifile from the given one.
 */
      public IFILE
getoff_ifile(ifile)
      IFILE ifile;
{
      IFILE newifile;
      
      if ((newifile = prev_ifile(ifile)) != NULL_IFILE)
            return (newifile);
      if ((newifile = next_ifile(ifile)) != NULL_IFILE)
            return (newifile);
      return (NULL_IFILE);
}

/*
 * Return the number of ifiles.
 */
      public int
nifile()
{
      return (ifiles);
}

/*
 * Find an ifile structure, given a filename.
 */
      static struct ifile *
find_ifile(filename)
      char *filename;
{
      register struct ifile *p;

      for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
            if (strcmp(filename, p->h_filename) == 0)
                  return (p);
      return (NULL);
}

/*
 * Get the ifile associated with a filename.
 * If the filename has not been seen before,
 * insert the new ifile after "prev" in the list.
 */
      public IFILE
get_ifile(filename, prev)
      char *filename;
      IFILE prev;
{
      register struct ifile *p;

      if ((p = find_ifile(filename)) == NULL)
            p = new_ifile(filename, int_ifile(prev));
      return (ext_ifile(p));
}

/*
 * Get the filename associated with a ifile.
 */
      public char *
get_filename(ifile)
      IFILE ifile;
{
      if (ifile == NULL)
            return (NULL);
      return (int_ifile(ifile)->h_filename);
}

/*
 * Get the index of the file associated with a ifile.
 */
      public int
get_index(ifile)
      IFILE ifile;
{
      return (int_ifile(ifile)->h_index); 
}

/*
 * Save the file position to be associated with a given file.
 */
      public void
store_pos(ifile, scrpos)
      IFILE ifile;
      struct scrpos *scrpos;
{
      int_ifile(ifile)->h_scrpos = *scrpos;
}

/*
 * Recall the file position associated with a file.
 * If no position has been associated with the file, return NULL_POSITION.
 */
      public void
get_pos(ifile, scrpos)
      IFILE ifile;
      struct scrpos *scrpos;
{
      *scrpos = int_ifile(ifile)->h_scrpos;
}

/*
 * Mark the ifile as "opened".
 */
      public void
set_open(ifile)
      IFILE ifile;
{
      int_ifile(ifile)->h_opened = 1;
}

/*
 * Return whether the ifile has been opened previously.
 */
      public int
opened(ifile)
      IFILE ifile;
{
      return (int_ifile(ifile)->h_opened);
}

      public void
hold_ifile(ifile, incr)
      IFILE ifile;
      int incr;
{
      int_ifile(ifile)->h_hold += incr;
}

      public int
held_ifile(ifile)
      IFILE ifile;
{
      return (int_ifile(ifile)->h_hold);
}

      public void *
get_filestate(ifile)
      IFILE ifile;
{
      return (int_ifile(ifile)->h_filestate);
}

      public void
set_filestate(ifile, filestate)
      IFILE ifile;
      void *filestate;
{
      int_ifile(ifile)->h_filestate = filestate;
}

#if 0
      public void
if_dump()
{
      register struct ifile *p;

      for (p = anchor.h_next;  p != &anchor;  p = p->h_next)
      {
            printf("%x: %d. <%s> pos %d,%x\n", 
                  p, p->h_index, p->h_filename, 
                  p->h_scrpos.ln, p->h_scrpos.pos);
            ch_dump(p->h_filestate);
      }
}
#endif

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