Function kwsincr

kwset.c:167–326

Add the given string to the contents of the keyword set. Return NULL for success, an error message otherwise. */

/* Add the given string to the contents of the keyword set.  Return NULL
   for success, an error message otherwise. */
const char *
kwsincr (kwset_t kws, char const *text, size_t len)
{
  struct kwset *kwset;
  register struct trie *trie;
  register unsigned char label;
  register struct tree *link;
  register int depth;
  struct tree *links[DEPTH_SIZE];
  enum { L, R } dirs[DEPTH_SIZE];
  struct tree *t, *r, *l, *rl, *lr;

  kwset = (struct kwset *) kws;
  trie = kwset->trie;
  text += len;

  /* Descend the trie (built of reversed keywords) character-by-character,
     installing new nodes when necessary. */
  while (len--)
    {
      label = kwset->trans ? kwset->trans[U(*--text)] : *--text;

      /* Descend the tree of outgoing links for this trie node,
	 looking for the current character and keeping track
	 of the path followed. */
      link = trie->links;
      links[0] = (struct tree *) &trie->links;
      dirs[0] = L;
      depth = 1;

      while (link && label != link->label)
	{
	  links[depth] = link;
	  if (label < link->label) {
	    dirs[depth++] = L;
	    link = link->llink;
	  } else {
	    dirs[depth++] = R;
	    link = link->rlink;
	  }
	}

      /* The current character doesn't have an outgoing link at
	 this trie node, so build a new trie node and install
	 a link in the current trie node's tree. */
      if (!link)
	{
	  link = (struct tree *) obstack_alloc(&kwset->obstack,
					       sizeof (struct tree));
	  if (!link)
	    return "memory exhausted";
	  link->llink = NULL;
	  link->rlink = NULL;
	  link->trie = (struct trie *) obstack_alloc(&kwset->obstack,
						     sizeof (struct trie));
	  if (!link->trie)
	    {
	      obstack_free(&kwset->obstack, link);