Add string search routines from GNU grep

kwset.c and kwset.h have been copied unmodified from commit e7ac713d^
in the GNU grep git repository (this is the last commit in the
repository licensed under GPLv2).

Signed-off-by: Fredrik Kuivinen <frekui@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/kwset.c b/kwset.c
new file mode 100644 (file)
index 0000000..e66193b
--- /dev/null
+++ b/kwset.c
@@ -0,0 +1,778 @@
+/* kwset.c - search for any of a set of keywords.
+   Copyright 1989, 1998, 2000, 2005 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
+   02110-1301, USA.  */
+
+/* Written August 1989 by Mike Haertel.
+   The author may be reached (Email) at the address mike@ai.mit.edu,
+   or (US mail) as Mike Haertel c/o Free Software Foundation. */
+
+/* The algorithm implemented by these routines bears a startling resemblence
+   to one discovered by Beate Commentz-Walter, although it is not identical.
+   See "A String Matching Algorithm Fast on the Average," Technical Report,
+   IBM-Germany, Scientific Center Heidelberg, Tiergartenstrasse 15, D-6900
+   Heidelberg, Germany.  See also Aho, A.V., and M. Corasick, "Efficient
+   String Matching:  An Aid to Bibliographic Search," CACM June 1975,
+   Vol. 18, No. 6, which describes the failure function used below. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include <sys/types.h>
+#include "system.h"
+#include "kwset.h"
+#include "obstack.h"
+
+#ifdef GREP
+extern char *xmalloc();
+# undef malloc
+# define malloc xmalloc
+#endif
+
+#define NCHAR (UCHAR_MAX + 1)
+#define obstack_chunk_alloc malloc
+#define obstack_chunk_free free
+
+#define U(c) ((unsigned char) (c))
+
+/* Balanced tree of edges and labels leaving a given trie node. */
+struct tree
+{
+  struct tree *llink;          /* Left link; MUST be first field. */
+  struct tree *rlink;          /* Right link (to larger labels). */
+  struct trie *trie;           /* Trie node pointed to by this edge. */
+  unsigned char label;         /* Label on this edge. */
+  char balance;                        /* Difference in depths of subtrees. */
+};
+
+/* Node of a trie representing a set of reversed keywords. */
+struct trie
+{
+  unsigned int accepting;      /* Word index of accepted word, or zero. */
+  struct tree *links;          /* Tree of edges leaving this node. */
+  struct trie *parent;         /* Parent of this node. */
+  struct trie *next;           /* List of all trie nodes in level order. */
+  struct trie *fail;           /* Aho-Corasick failure function. */
+  int depth;                   /* Depth of this node from the root. */
+  int shift;                   /* Shift function for search failures. */
+  int maxshift;                        /* Max shift of self and descendents. */
+};
+
+/* Structure returned opaquely to the caller, containing everything. */
+struct kwset
+{
+  struct obstack obstack;      /* Obstack for node allocation. */
+  int words;                   /* Number of words in the trie. */
+  struct trie *trie;           /* The trie itself. */
+  int mind;                    /* Minimum depth of an accepting node. */
+  int maxd;                    /* Maximum depth of any node. */
+  unsigned char delta[NCHAR];  /* Delta table for rapid search. */
+  struct trie *next[NCHAR];    /* Table of children of the root. */
+  char *target;                        /* Target string if there's only one. */
+  int mind2;                   /* Used in Boyer-Moore search for one string. */
+  char const *trans;           /* Character translation table. */
+};
+
+/* Allocate and initialize a keyword set object, returning an opaque
+   pointer to it.  Return NULL if memory is not available. */
+kwset_t
+kwsalloc (char const *trans)
+{
+  struct kwset *kwset;
+
+  kwset = (struct kwset *) malloc(sizeof (struct kwset));
+  if (!kwset)
+    return NULL;
+
+  obstack_init(&kwset->obstack);
+  kwset->words = 0;
+  kwset->trie
+    = (struct trie *) obstack_alloc(&kwset->obstack, sizeof (struct trie));
+  if (!kwset->trie)
+    {
+      kwsfree((kwset_t) kwset);
+      return NULL;
+    }
+  kwset->trie->accepting = 0;
+  kwset->trie->links = NULL;
+  kwset->trie->parent = NULL;
+  kwset->trie->next = NULL;
+  kwset->trie->fail = NULL;
+  kwset->trie->depth = 0;
+  kwset->trie->shift = 0;
+  kwset->mind = INT_MAX;
+  kwset->maxd = -1;
+  kwset->target = NULL;
+  kwset->trans = trans;
+
+  return (kwset_t) kwset;
+}
+
+/* This upper bound is valid for CHAR_BIT >= 4 and
+   exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }. */
+#define DEPTH_SIZE (CHAR_BIT + CHAR_BIT/2)
+
+/* 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);
+             return _("memory exhausted");
+           }
+         link->trie->accepting = 0;
+         link->trie->links = NULL;
+         link->trie->parent = trie;
+         link->trie->next = NULL;
+         link->trie->fail = NULL;
+         link->trie->depth = trie->depth + 1;
+         link->trie->shift = 0;
+         link->label = label;
+         link->balance = 0;
+
+         /* Install the new tree node in its parent. */
+         if (dirs[--depth] == L)
+           links[depth]->llink = link;
+         else
+           links[depth]->rlink = link;
+
+         /* Back up the tree fixing the balance flags. */
+         while (depth && !links[depth]->balance)
+           {
+             if (dirs[depth] == L)
+               --links[depth]->balance;
+             else
+               ++links[depth]->balance;
+             --depth;
+           }
+
+         /* Rebalance the tree by pointer rotations if necessary. */
+         if (depth && ((dirs[depth] == L && --links[depth]->balance)
+                       || (dirs[depth] == R && ++links[depth]->balance)))
+           {
+             switch (links[depth]->balance)
+               {
+               case (char) -2:
+                 switch (dirs[depth + 1])
+                   {
+                   case L:
+                     r = links[depth], t = r->llink, rl = t->rlink;
+                     t->rlink = r, r->llink = rl;
+                     t->balance = r->balance = 0;
+                     break;
+                   case R:
+                     r = links[depth], l = r->llink, t = l->rlink;
+                     rl = t->rlink, lr = t->llink;
+                     t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
+                     l->balance = t->balance != 1 ? 0 : -1;
+                     r->balance = t->balance != (char) -1 ? 0 : 1;
+                     t->balance = 0;
+                     break;
+                   default:
+                     abort ();
+                   }
+                 break;
+               case 2:
+                 switch (dirs[depth + 1])
+                   {
+                   case R:
+                     l = links[depth], t = l->rlink, lr = t->llink;
+                     t->llink = l, l->rlink = lr;
+                     t->balance = l->balance = 0;
+                     break;
+                   case L:
+                     l = links[depth], r = l->rlink, t = r->llink;
+                     lr = t->llink, rl = t->rlink;
+                     t->llink = l, l->rlink = lr, t->rlink = r, r->llink = rl;
+                     l->balance = t->balance != 1 ? 0 : -1;
+                     r->balance = t->balance != (char) -1 ? 0 : 1;
+                     t->balance = 0;
+                     break;
+                   default:
+                     abort ();
+                   }
+                 break;
+               default:
+                 abort ();
+               }
+
+             if (dirs[depth - 1] == L)
+               links[depth - 1]->llink = t;
+             else
+               links[depth - 1]->rlink = t;
+           }
+       }
+
+      trie = link->trie;
+    }
+
+  /* Mark the node we finally reached as accepting, encoding the
+     index number of this word in the keyword set so far. */
+  if (!trie->accepting)
+    trie->accepting = 1 + 2 * kwset->words;
+  ++kwset->words;
+
+  /* Keep track of the longest and shortest string of the keyword set. */
+  if (trie->depth < kwset->mind)
+    kwset->mind = trie->depth;
+  if (trie->depth > kwset->maxd)
+    kwset->maxd = trie->depth;
+
+  return NULL;
+}
+
+/* Enqueue the trie nodes referenced from the given tree in the
+   given queue. */
+static void
+enqueue (struct tree *tree, struct trie **last)
+{
+  if (!tree)
+    return;
+  enqueue(tree->llink, last);
+  enqueue(tree->rlink, last);
+  (*last) = (*last)->next = tree->trie;
+}
+
+/* Compute the Aho-Corasick failure function for the trie nodes referenced
+   from the given tree, given the failure function for their parent as
+   well as a last resort failure node. */
+static void
+treefails (register struct tree const *tree, struct trie const *fail,
+          struct trie *recourse)
+{
+  register struct tree *link;
+
+  if (!tree)
+    return;
+
+  treefails(tree->llink, fail, recourse);
+  treefails(tree->rlink, fail, recourse);
+
+  /* Find, in the chain of fails going back to the root, the first
+     node that has a descendent on the current label. */
+  while (fail)
+    {
+      link = fail->links;
+      while (link && tree->label != link->label)
+       if (tree->label < link->label)
+         link = link->llink;
+       else
+         link = link->rlink;
+      if (link)
+       {
+         tree->trie->fail = link->trie;
+         return;
+       }
+      fail = fail->fail;
+    }
+
+  tree->trie->fail = recourse;
+}
+
+/* Set delta entries for the links of the given tree such that
+   the preexisting delta value is larger than the current depth. */
+static void
+treedelta (register struct tree const *tree,
+          register unsigned int depth,
+          unsigned char delta[])
+{
+  if (!tree)
+    return;
+  treedelta(tree->llink, depth, delta);
+  treedelta(tree->rlink, depth, delta);
+  if (depth < delta[tree->label])
+    delta[tree->label] = depth;
+}
+
+/* Return true if A has every label in B. */
+static int
+hasevery (register struct tree const *a, register struct tree const *b)
+{
+  if (!b)
+    return 1;
+  if (!hasevery(a, b->llink))
+    return 0;
+  if (!hasevery(a, b->rlink))
+    return 0;
+  while (a && b->label != a->label)
+    if (b->label < a->label)
+      a = a->llink;
+    else
+      a = a->rlink;
+  return !!a;
+}
+
+/* Compute a vector, indexed by character code, of the trie nodes
+   referenced from the given tree. */
+static void
+treenext (struct tree const *tree, struct trie *next[])
+{
+  if (!tree)
+    return;
+  treenext(tree->llink, next);
+  treenext(tree->rlink, next);
+  next[tree->label] = tree->trie;
+}
+
+/* Compute the shift for each trie node, as well as the delta
+   table and next cache for the given keyword set. */
+const char *
+kwsprep (kwset_t kws)
+{
+  register struct kwset *kwset;
+  register int i;
+  register struct trie *curr;
+  register char const *trans;
+  unsigned char delta[NCHAR];
+
+  kwset = (struct kwset *) kws;
+
+  /* Initial values for the delta table; will be changed later.  The
+     delta entry for a given character is the smallest depth of any
+     node at which an outgoing edge is labeled by that character. */
+  memset(delta, kwset->mind < UCHAR_MAX ? kwset->mind : UCHAR_MAX, NCHAR);
+
+  /* Check if we can use the simple boyer-moore algorithm, instead
+     of the hairy commentz-walter algorithm. */
+  if (kwset->words == 1 && kwset->trans == NULL)
+    {
+      char c;
+
+      /* Looking for just one string.  Extract it from the trie. */
+      kwset->target = obstack_alloc(&kwset->obstack, kwset->mind);
+      if (!kwset->target)
+       return _("memory exhausted");
+      for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i)
+       {
+         kwset->target[i] = curr->links->label;
+         curr = curr->links->trie;
+       }
+      /* Build the Boyer Moore delta.  Boy that's easy compared to CW. */
+      for (i = 0; i < kwset->mind; ++i)
+       delta[U(kwset->target[i])] = kwset->mind - (i + 1);
+      /* Find the minimal delta2 shift that we might make after
+        a backwards match has failed. */
+      c = kwset->target[kwset->mind - 1];
+      for (i = kwset->mind - 2; i >= 0; --i)
+       if (kwset->target[i] == c)
+         break;
+      kwset->mind2 = kwset->mind - (i + 1);
+    }
+  else
+    {
+      register struct trie *fail;
+      struct trie *last, *next[NCHAR];
+
+      /* Traverse the nodes of the trie in level order, simultaneously
+        computing the delta table, failure function, and shift function. */
+      for (curr = last = kwset->trie; curr; curr = curr->next)
+       {
+         /* Enqueue the immediate descendents in the level order queue. */
+         enqueue(curr->links, &last);
+
+         curr->shift = kwset->mind;
+         curr->maxshift = kwset->mind;
+
+         /* Update the delta table for the descendents of this node. */
+         treedelta(curr->links, curr->depth, delta);
+
+         /* Compute the failure function for the decendents of this node. */
+         treefails(curr->links, curr->fail, kwset->trie);
+
+         /* Update the shifts at each node in the current node's chain
+            of fails back to the root. */
+         for (fail = curr->fail; fail; fail = fail->fail)
+           {
+             /* If the current node has some outgoing edge that the fail
+                doesn't, then the shift at the fail should be no larger
+                than the difference of their depths. */
+             if (!hasevery(fail->links, curr->links))
+               if (curr->depth - fail->depth < fail->shift)
+                 fail->shift = curr->depth - fail->depth;
+
+             /* If the current node is accepting then the shift at the
+                fail and its descendents should be no larger than the
+                difference of their depths. */
+             if (curr->accepting && fail->maxshift > curr->depth - fail->depth)
+               fail->maxshift = curr->depth - fail->depth;
+           }
+       }
+
+      /* Traverse the trie in level order again, fixing up all nodes whose
+        shift exceeds their inherited maxshift. */
+      for (curr = kwset->trie->next; curr; curr = curr->next)
+       {
+         if (curr->maxshift > curr->parent->maxshift)
+           curr->maxshift = curr->parent->maxshift;
+         if (curr->shift > curr->maxshift)
+           curr->shift = curr->maxshift;
+       }
+
+      /* Create a vector, indexed by character code, of the outgoing links
+        from the root node. */
+      for (i = 0; i < NCHAR; ++i)
+       next[i] = NULL;
+      treenext(kwset->trie->links, next);
+
+      if ((trans = kwset->trans) != NULL)
+       for (i = 0; i < NCHAR; ++i)
+         kwset->next[i] = next[U(trans[i])];
+      else
+       memcpy(kwset->next, next, NCHAR * sizeof(struct trie *));
+    }
+
+  /* Fix things up for any translation table. */
+  if ((trans = kwset->trans) != NULL)
+    for (i = 0; i < NCHAR; ++i)
+      kwset->delta[i] = delta[U(trans[i])];
+  else
+    memcpy(kwset->delta, delta, NCHAR);
+
+  return NULL;
+}
+
+/* Fast boyer-moore search. */
+static size_t
+bmexec (kwset_t kws, char const *text, size_t size)
+{
+  struct kwset const *kwset;
+  register unsigned char const *d1;
+  register char const *ep, *sp, *tp;
+  register int d, gc, i, len, md2;
+
+  kwset = (struct kwset const *) kws;
+  len = kwset->mind;
+
+  if (len == 0)
+    return 0;
+  if (len > size)
+    return -1;
+  if (len == 1)
+    {
+      tp = memchr (text, kwset->target[0], size);
+      return tp ? tp - text : -1;
+    }
+
+  d1 = kwset->delta;
+  sp = kwset->target + len;
+  gc = U(sp[-2]);
+  md2 = kwset->mind2;
+  tp = text + len;
+
+  /* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */
+  if (size > 12 * len)
+    /* 11 is not a bug, the initial offset happens only once. */
+    for (ep = text + size - 11 * len;;)
+      {
+       while (tp <= ep)
+         {
+           d = d1[U(tp[-1])], tp += d;
+           d = d1[U(tp[-1])], tp += d;
+           if (d == 0)
+             goto found;
+           d = d1[U(tp[-1])], tp += d;
+           d = d1[U(tp[-1])], tp += d;
+           d = d1[U(tp[-1])], tp += d;
+           if (d == 0)
+             goto found;
+           d = d1[U(tp[-1])], tp += d;
+           d = d1[U(tp[-1])], tp += d;
+           d = d1[U(tp[-1])], tp += d;
+           if (d == 0)
+             goto found;
+           d = d1[U(tp[-1])], tp += d;
+           d = d1[U(tp[-1])], tp += d;
+         }
+       break;
+      found:
+       if (U(tp[-2]) == gc)
+         {
+           for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
+             ;
+           if (i > len)
+             return tp - len - text;
+         }
+       tp += md2;
+      }
+
+  /* Now we have only a few characters left to search.  We
+     carefully avoid ever producing an out-of-bounds pointer. */
+  ep = text + size;
+  d = d1[U(tp[-1])];
+  while (d <= ep - tp)
+    {
+      d = d1[U((tp += d)[-1])];
+      if (d != 0)
+       continue;
+      if (U(tp[-2]) == gc)
+       {
+         for (i = 3; i <= len && U(tp[-i]) == U(sp[-i]); ++i)
+           ;
+         if (i > len)
+           return tp - len - text;
+       }
+      d = md2;
+    }
+
+  return -1;
+}
+
+/* Hairy multiple string search. */
+static size_t
+cwexec (kwset_t kws, char const *text, size_t len, struct kwsmatch *kwsmatch)
+{
+  struct kwset const *kwset;
+  struct trie * const *next;
+  struct trie const *trie;
+  struct trie const *accept;
+  char const *beg, *lim, *mch, *lmch;
+  register unsigned char c;
+  register unsigned char const *delta;
+  register int d;
+  register char const *end, *qlim;
+  register struct tree const *tree;
+  register char const *trans;
+
+#ifdef lint
+  accept = NULL;
+#endif
+
+  /* Initialize register copies and look for easy ways out. */
+  kwset = (struct kwset *) kws;
+  if (len < kwset->mind)
+    return -1;
+  next = kwset->next;
+  delta = kwset->delta;
+  trans = kwset->trans;
+  lim = text + len;
+  end = text;
+  if ((d = kwset->mind) != 0)
+    mch = NULL;
+  else
+    {
+      mch = text, accept = kwset->trie;
+      goto match;
+    }
+
+  if (len >= 4 * kwset->mind)
+    qlim = lim - 4 * kwset->mind;
+  else
+    qlim = NULL;
+
+  while (lim - end >= d)
+    {
+      if (qlim && end <= qlim)
+       {
+         end += d - 1;
+         while ((d = delta[c = *end]) && end < qlim)
+           {
+             end += d;
+             end += delta[U(*end)];
+             end += delta[U(*end)];
+           }
+         ++end;
+       }
+      else
+       d = delta[c = (end += d)[-1]];
+      if (d)
+       continue;
+      beg = end - 1;
+      trie = next[c];
+      if (trie->accepting)
+       {
+         mch = beg;
+         accept = trie;
+       }
+      d = trie->shift;
+      while (beg > text)
+       {
+         c = trans ? trans[U(*--beg)] : *--beg;
+         tree = trie->links;
+         while (tree && c != tree->label)
+           if (c < tree->label)
+             tree = tree->llink;
+           else
+             tree = tree->rlink;
+         if (tree)
+           {
+             trie = tree->trie;
+             if (trie->accepting)
+               {
+                 mch = beg;
+                 accept = trie;
+               }
+           }
+         else
+           break;
+         d = trie->shift;
+       }
+      if (mch)
+       goto match;
+    }
+  return -1;
+
+ match:
+  /* Given a known match, find the longest possible match anchored
+     at or before its starting point.  This is nearly a verbatim
+     copy of the preceding main search loops. */
+  if (lim - mch > kwset->maxd)
+    lim = mch + kwset->maxd;
+  lmch = 0;
+  d = 1;
+  while (lim - end >= d)
+    {
+      if ((d = delta[c = (end += d)[-1]]) != 0)
+       continue;
+      beg = end - 1;
+      if (!(trie = next[c]))
+       {
+         d = 1;
+         continue;
+       }
+      if (trie->accepting && beg <= mch)
+       {
+         lmch = beg;
+         accept = trie;
+       }
+      d = trie->shift;
+      while (beg > text)
+       {
+         c = trans ? trans[U(*--beg)] : *--beg;
+         tree = trie->links;
+         while (tree && c != tree->label)
+           if (c < tree->label)
+             tree = tree->llink;
+           else
+             tree = tree->rlink;
+         if (tree)
+           {
+             trie = tree->trie;
+             if (trie->accepting && beg <= mch)
+               {
+                 lmch = beg;
+                 accept = trie;
+               }
+           }
+         else
+           break;
+         d = trie->shift;
+       }
+      if (lmch)
+       {
+         mch = lmch;
+         goto match;
+       }
+      if (!d)
+       d = 1;
+    }
+
+  if (kwsmatch)
+    {
+      kwsmatch->index = accept->accepting / 2;
+      kwsmatch->offset[0] = mch - text;
+      kwsmatch->size[0] = accept->depth;
+    }
+  return mch - text;
+}
+
+/* Search through the given text for a match of any member of the
+   given keyword set.  Return a pointer to the first character of
+   the matching substring, or NULL if no match is found.  If FOUNDLEN
+   is non-NULL store in the referenced location the length of the
+   matching substring.  Similarly, if FOUNDIDX is non-NULL, store
+   in the referenced location the index number of the particular
+   keyword matched. */
+size_t
+kwsexec (kwset_t kws, char const *text, size_t size,
+        struct kwsmatch *kwsmatch)
+{
+  struct kwset const *kwset = (struct kwset *) kws;
+  if (kwset->words == 1 && kwset->trans == NULL)
+    {
+      size_t ret = bmexec (kws, text, size);
+      if (kwsmatch != NULL && ret != (size_t) -1)
+       {
+         kwsmatch->index = 0;
+         kwsmatch->offset[0] = ret;
+         kwsmatch->size[0] = kwset->mind;
+       }
+      return ret;
+    }
+  else
+    return cwexec(kws, text, size, kwsmatch);
+}
+
+/* Free the components of the given keyword set. */
+void
+kwsfree (kwset_t kws)
+{
+  struct kwset *kwset;
+
+  kwset = (struct kwset *) kws;
+  obstack_free(&kwset->obstack, NULL);
+  free(kws);
+}

diff --git a/kwset.h b/kwset.h
new file mode 100644 (file)
index 0000000..ab530b3
--- /dev/null
+++ b/kwset.h
@@ -0,0 +1,56 @@
+/* kwset.h - header declaring the keyword set library.
+   Copyright (C) 1989, 1998, 2005 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA
+   02110-1301, USA.  */
+
+/* Written August 1989 by Mike Haertel.
+   The author may be reached (Email) at the address mike@ai.mit.edu,
+   or (US mail) as Mike Haertel c/o Free Software Foundation. */
+
+struct kwsmatch
+{
+  int index;                   /* Index number of matching keyword. */
+  size_t offset[1];            /* Offset of each submatch. */
+  size_t size[1];              /* Length of each submatch. */
+};
+
+typedef ptr_t kwset_t;
+
+/* Return an opaque pointer to a newly allocated keyword set, or NULL
+   if enough memory cannot be obtained.  The argument if non-NULL
+   specifies a table of character translations to be applied to all
+   pattern and search text. */
+extern kwset_t kwsalloc PARAMS((char const *));
+
+/* Incrementally extend the keyword set to include the given string.
+   Return NULL for success, or an error message.  Remember an index
+   number for each keyword included in the set. */
+extern const char *kwsincr PARAMS((kwset_t, char const *, size_t));
+
+/* When the keyword set has been completely built, prepare it for
+   use.  Return NULL for success, or an error message. */
+extern const char *kwsprep PARAMS((kwset_t));
+
+/* Search through the given buffer for a member of the keyword set.
+   Return a pointer to the leftmost longest match found, or NULL if
+   no match is found.  If foundlen is non-NULL, store the length of
+   the matching substring in the integer it points to.  Similarly,
+   if foundindex is non-NULL, store the index of the particular
+   keyword found therein. */
+extern size_t kwsexec PARAMS((kwset_t, char const *, size_t, struct kwsmatch *));
+
+/* Deallocate the given keyword set and all its associated storage. */
+extern void kwsfree PARAMS((kwset_t));