/* kwset.c - search for any of a set of keywords.
Copyright (C) 1989, 1998, 2000, 2005, 2007, 2009-2017 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 3, 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. */
/* For the Aho-Corasick algorithm, see:
Aho AV, Corasick MJ. Efficient string matching: an aid to
bibliographic search. CACM 18, 6 (1975), 333-40
<http://dx.doi.org/10.1145/360825.360855>, which describes the
failure function used below.
For the Boyer-Moore algorithm, see: Boyer RS, Moore JS.
A fast string searching algorithm. CACM 20, 10 (1977), 762-72
<http://dx.doi.org/10.1145/359842.359859>.
For a survey of more-recent string matching algorithms that might
help improve performance, see: Faro S, Lecroq T. The exact online
string matching problem: a review of the most recent results.
ACM Computing Surveys 45, 2 (2013), 13
<http://dx.doi.org/10.1145/2431211.2431212>. */
#include <config.h>
#include "kwset.h"
#include <stdint.h>
#include <sys/types.h>
#include "system.h"
#include "intprops.h"
#include "memchr2.h"
#include "obstack.h"
#include "xalloc.h"
#include "verify.h"
#define obstack_chunk_alloc xmalloc
#define obstack_chunk_free free
static unsigned char
U (char ch)
{
return to_uchar (ch);
}
/* 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 keywords. */
struct trie
{
/* If an accepting node, this is either 2*W + 1 where W is the word
index, or is SIZE_MAX if Aho-Corasick is in use and FAIL
specifies where to look for more info. If not an accepting node,
this is zero. */
size_t accepting;
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. */
ptrdiff_t depth; /* Depth of this node from the root. */
ptrdiff_t shift; /* Shift function for search failures. */
ptrdiff_t maxshift; /* Max shift of self and descendants. */
};
/* Structure returned opaquely to the caller, containing everything. */
struct kwset
{
struct obstack obstack; /* Obstack for node allocation. */
ptrdiff_t words; /* Number of words in the trie. */
struct trie *trie; /* The trie itself. */
ptrdiff_t mind; /* Minimum depth of an accepting node. */
ptrdiff_t 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. */
ptrdiff_t *shift; /* Used in Boyer-Moore search for one
string. */
char const *trans; /* Character translation table. */
/* This helps to match a terminal byte, which is the first byte
for Aho-Corasick, and the last byte for Boyer-More. If all the
patterns have the same terminal byte (after translation via TRANS
if TRANS is nonnull), then this is that byte as an unsigned char.
Otherwise this is -1 if there is disagreement among the strings
about terminal bytes, and -2 if there are no terminal bytes and
no disagreement because all the patterns are empty. */
int gc1;
/* This helps to match a terminal byte. If 0 <= GC1HELP, B is
terminal when B == GC1 || B == GC1HELP (note that GC1 == GCHELP
is common here). This is typically faster than evaluating
to_uchar (TRANS[B]) == GC1. */
int gc1help;
/* If the string has two or more bytes, this is the penultimate byte,
after translation via TRANS if TRANS is nonnull. This variable
is used only by Boyer-Moore. */
char gc2;
/* kwsexec implementation. */
ptrdiff_t (*kwsexec) (kwset_t, char const *, ptrdiff_t,
struct kwsmatch *, bool);
};
/* Use TRANS to transliterate C. A null TRANS does no transliteration. */
static inline char
tr (char const *trans, char c)
{
return trans ? trans[U(c)] : c;
}
static ptrdiff_t acexec (kwset_t, char const *, ptrdiff_t,
struct kwsmatch *, bool);
static ptrdiff_t bmexec (kwset_t, char const *, ptrdiff_t,
struct kwsmatch *, bool);
/* Return a newly allocated keyword set. A nonnull TRANS specifies a
table of character translations to be applied to all pattern and
search text. */
kwset_t
kwsalloc (char const *trans)
{
struct kwset *kwset = xmalloc (sizeof *kwset);
obstack_init (&kwset->obstack);
kwset->words = 0;
kwset->trie = obstack_alloc (&kwset->obstack, sizeof *kwset->trie);
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 = PTRDIFF_MAX;
kwset->maxd = -1;
kwset->target = NULL;
kwset->trans = trans;
kwset->kwsexec = acexec;
return kwset;
}
/* This upper bound is valid for CHAR_BIT >= 4 and
exact for CHAR_BIT in { 4..11, 13, 15, 17, 19 }. */
enum { DEPTH_SIZE = CHAR_BIT + CHAR_BIT / 2 };
/* Add the given string to the contents of the keyword set. */
void
kwsincr (kwset_t kwset, char const *text, ptrdiff_t len)
{
assume (0 <= len);
struct trie *trie = kwset->trie;
char const *trans = kwset->trans;
bool reverse = kwset->kwsexec == bmexec;
if (reverse)
text += len;
/* Descend the trie (built of keywords) character-by-character,
installing new nodes when necessary. */
while (len--)
{
unsigned char uc = reverse ? *--text : *text++;
unsigned char label = trans ? trans[uc] : uc;
/* Descend the tree of outgoing links for this trie node,
looking for the current character and keeping track
of the path followed. */
struct tree *cur = trie->links;
struct tree *links[DEPTH_SIZE];
enum { L, R } dirs[DEPTH_SIZE];
links[0] = (struct tree *) &trie->links;
dirs[0] = L;
ptrdiff_t depth = 1;
while (cur && label != cur->label)
{
links[depth] = cur;
if (label < cur->label)
dirs[depth++] = L, cur = cur->llink;
else
dirs[depth++] = R, cur = cur->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 (!cur)
{
cur = obstack_alloc (&kwset->obstack, sizeof *cur);
cur->llink = NULL;
cur->rlink = NULL;
cur->trie = obstack_alloc (&kwset->obstack, sizeof *cur->trie);
cur->trie->accepting = 0;
cur->trie->links = NULL;
cur->trie->parent = trie;
cur->trie->next = NULL;
cur->trie->fail = NULL;
cur->trie->depth = trie->depth + 1;
cur->trie->shift = 0;
cur->label = label;
cur->balance = 0;
/* Install the new tree node in its parent. */
if (dirs[--depth] == L)
links[depth]->llink = cur;
else
links[depth]->rlink = cur;
/* 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)))
{
struct tree *t, *r, *l, *rl, *lr;
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 = cur->trie;
}
/* Mark the node finally reached as accepting, encoding the
index number of this word in the keyword set so far. */
if (!trie->accepting)
{
size_t words = kwset->words;
trie->accepting = 2 * words + 1;
}
++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;
}
ptrdiff_t
kwswords (kwset_t kwset)
{
return kwset->words;
}
/* 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 (struct tree const *tree, struct trie const *fail,
struct trie *recourse, bool reverse)
{
struct tree *cur;
if (!tree)
return;
treefails (tree->llink, fail, recourse, reverse);
treefails (tree->rlink, fail, recourse, reverse);
/* Find, in the chain of fails going back to the root, the first
node that has a descendant on the current label. */
while (fail)
{
cur = fail->links;
while (cur && tree->label != cur->label)
if (tree->label < cur->label)
cur = cur->llink;
else
cur = cur->rlink;
if (cur)
{
tree->trie->fail = cur->trie;
if (!reverse && cur->trie->accepting && !tree->trie->accepting)
tree->trie->accepting = SIZE_MAX;
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 (struct tree const *tree, ptrdiff_t 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 bool _GL_ATTRIBUTE_PURE
hasevery (struct tree const *a, struct tree const *b)
{
if (!b)
return true;
if (!hasevery (a, b->llink))
return false;
if (!hasevery (a, b->rlink))
return false;
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;
}
/* Prepare a built keyword set for use. */
void
kwsprep (kwset_t kwset)
{
char const *trans = kwset->trans;
ptrdiff_t i;
unsigned char deltabuf[NCHAR];
unsigned char *delta = trans ? deltabuf : kwset->delta;
struct trie *curr, *last;
/* Use Boyer-Moore if just one pattern, Aho-Corasick otherwise. */
bool reverse = kwset->words == 1;
if (reverse)
{
kwset_t new_kwset;
/* Enqueue the immediate descendants in the level order queue. */
for (curr = last = kwset->trie; curr; curr = curr->next)
enqueue (curr->links, &last);
/* Looking for just one string. Extract it from the trie. */
kwset->target = obstack_alloc (&kwset->obstack, kwset->mind);
for (i = 0, curr = kwset->trie; i < kwset->mind; ++i)
{
kwset->target[i] = curr->links->label;
curr = curr->next;
}
new_kwset = kwsalloc (kwset->trans);
new_kwset->kwsexec = bmexec;
kwsincr (new_kwset, kwset->target, kwset->mind);
obstack_free (&kwset->obstack, NULL);
*kwset = *new_kwset;
free (new_kwset);
}
/* 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, MIN (kwset->mind, UCHAR_MAX), sizeof deltabuf);
/* 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 descendants in the level order queue. */
enqueue (curr->links, &last);
/* Update the delta table for the descendants of this node. */
treedelta (curr->links, curr->depth, delta);
/* Compute the failure function for the descendants of this node. */
treefails (curr->links, curr->fail, kwset->trie, reverse);
if (reverse)
{
curr->shift = kwset->mind;
curr->maxshift = kwset->mind;
/* Update the shifts at each node in the current node's chain
of fails back to the root. */
struct trie *fail;
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 descendants 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;
}
}
}
if (reverse)
{
/* 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. Accumulate GC1 and GC1HELP. */
struct trie *nextbuf[NCHAR];
struct trie **next = trans ? nextbuf : kwset->next;
memset (next, 0, sizeof nextbuf);
treenext (kwset->trie->links, next);
int gc1 = -2;
int gc1help = -1;
for (i = 0; i < NCHAR; i++)
{
int ti = i;
if (trans)
{
ti = U(trans[i]);
kwset->next[i] = next[ti];
}
if (kwset->next[i])
{
if (gc1 < -1)
{
gc1 = ti;
gc1help = i;
}
else if (gc1 == ti)
gc1help = gc1help == ti ? i : -1;
else if (i == ti && gc1 == gc1help)
gc1help = i;
else
gc1 = -1;
}
}
kwset->gc1 = gc1;
kwset->gc1help = gc1help;
if (reverse)
{
/* Looking for just one string. Extract it from the trie. */
kwset->target = obstack_alloc (&kwset->obstack, kwset->mind);
for (i = kwset->mind - 1, curr = kwset->trie; i >= 0; --i)
{
kwset->target[i] = curr->links->label;
curr = curr->next;
}
if (kwset->mind > 1)
{
/* Looking for the delta2 shift that might be made after a
backwards match has failed. Extract it from the trie. */
kwset->shift
= obstack_alloc (&kwset->obstack,
sizeof *kwset->shift * (kwset->mind - 1));
for (i = 0, curr = kwset->trie->next; i < kwset->mind - 1; ++i)
{
kwset->shift[i] = curr->shift;
curr = curr->next;
}
/* The penultimate byte. */
kwset->gc2 = tr (trans, kwset->target[kwset->mind - 2]);
}
}
/* Fix things up for any translation table. */
if (trans)
for (i = 0; i < NCHAR; ++i)
kwset->delta[i] = delta[U(trans[i])];
}
/* Delta2 portion of a Boyer-Moore search. *TP is the string text
pointer; it is updated in place. EP is the end of the string text,
and SP the end of the pattern. LEN is the pattern length; it must
be at least 2. TRANS, if nonnull, is the input translation table.
GC1 and GC2 are the last and second-from last bytes of the pattern,
transliterated by TRANS; the caller precomputes them for
efficiency. If D1 is nonnull, it is a delta1 table for shifting *TP
when failing. KWSET->shift says how much to shift. */
static inline bool
bm_delta2_search (char const **tpp, char const *ep, char const *sp,
ptrdiff_t len,
char const *trans, char gc1, char gc2,
unsigned char const *d1, kwset_t kwset)
{
char const *tp = *tpp;
ptrdiff_t d = len, skip = 0;
while (true)
{
ptrdiff_t i = 2;
if (tr (trans, tp[-2]) == gc2)
{
while (++i <= d)
if (tr (trans, tp[-i]) != tr (trans, sp[-i]))
break;
if (i > d)
{
for (i = d + skip + 1; i <= len; ++i)
if (tr (trans, tp[-i]) != tr (trans, sp[-i]))
break;
if (i > len)
{
*tpp = tp - len;
return true;
}
}
}
tp += d = kwset->shift[i - 2];
if (tp > ep)
break;
if (tr (trans, tp[-1]) != gc1)
{
if (d1)
tp += d1[U(tp[-1])];
break;
}
skip = i - 1;
}
*tpp = tp;
return false;
}
/* Return the address of the first byte in the buffer S (of size N)
that matches the terminal byte specified by KWSET, or NULL if there
is no match. KWSET->gc1 should be nonnegative. */
static char const *
memchr_kwset (char const *s, ptrdiff_t n, kwset_t kwset)
{
char const *slim = s + n;
if (kwset->gc1help < 0)
{
for (; s < slim; s++)
if (kwset->next[U(*s)])
return s;
}
else
{
int small_heuristic = 2;
size_t small_bytes = small_heuristic * sizeof (unsigned long int);
while (s < slim)
{
if (kwset->next[U(*s)])
return s;
s++;
if ((uintptr_t) s % small_bytes == 0)
return memchr2 (s, kwset->gc1, kwset->gc1help, slim - s);
}
}
return NULL;
}
/* Fast Boyer-Moore search (inlinable version). */
static inline ptrdiff_t
bmexec_trans (kwset_t kwset, char const *text, ptrdiff_t size)
{
assume (0 <= size);
unsigned char const *d1;
char const *ep, *sp, *tp;
int d;
ptrdiff_t len = kwset->mind;
char const *trans = kwset->trans;
if (len == 0)
return 0;
if (len > size)
return -1;
if (len == 1)
{
tp = memchr_kwset (text, size, kwset);
return tp ? tp - text : -1;
}
d1 = kwset->delta;
sp = kwset->target + len;
tp = text + len;
char gc1 = kwset->gc1;
char gc2 = kwset->gc2;
/* Significance of 12: 1 (initial offset) + 10 (skip loop) + 1 (md2). */
ptrdiff_t len12;
if (!INT_MULTIPLY_WRAPV (len, 12, &len12) && len12 < size)
/* 11 is not a bug, the initial offset happens only once. */
for (ep = text + size - 11 * len; tp <= ep; )
{
char const *tp0 = tp;
d = d1[U(tp[-1])], tp += d;
d = d1[U(tp[-1])], tp += d;
if (d != 0)
{
d = d1[U(tp[-1])], tp += d;
d = d1[U(tp[-1])], tp += d;
d = d1[U(tp[-1])], tp += d;
if (d != 0)
{
d = d1[U(tp[-1])], tp += d;
d = d1[U(tp[-1])], tp += d;
d = d1[U(tp[-1])], tp += d;
if (d != 0)
{
d = d1[U(tp[-1])], tp += d;
d = d1[U(tp[-1])], tp += d;
/* As a heuristic, prefer memchr to seeking by
delta1 when the latter doesn't advance much. */
int advance_heuristic = 16 * sizeof (long);
if (advance_heuristic <= tp - tp0)
continue;
tp--;
tp = memchr_kwset (tp, text + size - tp, kwset);
if (! tp)
return -1;
tp++;
if (ep <= tp)
break;
}
}
}
if (bm_delta2_search (&tp, ep, sp, len, trans, gc1, gc2, d1, kwset))
return tp - text;
}
/* Now only a few characters are left to search. 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 (bm_delta2_search (&tp, ep, sp, len, trans, gc1, gc2, NULL, kwset))
return tp - text;
}
return -1;
}
/* Fast Boyer-Moore search. */
static ptrdiff_t
bmexec (kwset_t kwset, char const *text, ptrdiff_t size,
struct kwsmatch *kwsmatch, bool longest)
{
/* Help the compiler inline in two ways, depending on whether
kwset->trans is null. */
ptrdiff_t ret = (IGNORE_DUPLICATE_BRANCH_WARNING
(kwset->trans
? bmexec_trans (kwset, text, size)
: bmexec_trans (kwset, text, size)));
if (0 <= ret)
{
kwsmatch->index = 0;
kwsmatch->offset[0] = ret;
kwsmatch->size[0] = kwset->mind;
}
return ret;
}
/* Hairy multiple string search with the Aho-Corasick algorithm.
(inlinable version) */
static inline ptrdiff_t
acexec_trans (kwset_t kwset, char const *text, ptrdiff_t len,
struct kwsmatch *kwsmatch, bool longest)
{
struct trie const *trie, *accept;
char const *tp, *left, *lim;
struct tree const *tree;
char const *trans;
/* Initialize register copies and look for easy ways out. */
if (len < kwset->mind)
return -1;
trans = kwset->trans;
trie = kwset->trie;
lim = text + len;
tp = text;
if (!trie->accepting)
{
unsigned char c;
int gc1 = kwset->gc1;
while (true)
{
if (gc1 < 0)
{
while (! (trie = kwset->next[c = tr (trans, *tp++)]))
if (tp >= lim)
return -1;
}
else
{
tp = memchr_kwset (tp, lim - tp, kwset);
if (!tp)
return -1;
c = tr (trans, *tp++);
trie = kwset->next[c];
}
while (true)
{
if (trie->accepting)
goto match;
if (tp >= lim)
return -1;
c = tr (trans, *tp++);
for (tree = trie->links; c != tree->label; )
{
tree = c < tree->label ? tree->llink : tree->rlink;
if (! tree)
{
trie = trie->fail;
if (!trie)
{
trie = kwset->next[c];
if (trie)
goto have_trie;
if (tp >= lim)
return -1;
goto next_c;
}
if (trie->accepting)
{
--tp;
goto match;
}
tree = trie->links;
}
}
trie = tree->trie;
have_trie:;
}
next_c:;
}
}
match:
accept = trie;
while (accept->accepting == SIZE_MAX)
accept = accept->fail;
left = tp - accept->depth;
/* Try left-most longest match. */
if (longest)
{
while (tp < lim)
{
struct trie const *accept1;
char const *left1;
unsigned char c = tr (trans, *tp++);
do
{
tree = trie->links;
while (tree && c != tree->label)
tree = c < tree->label ? tree->llink : tree->rlink;
}
while (!tree && (trie = trie->fail) && accept->depth <= trie->depth);
if (!tree)
break;
trie = tree->trie;
if (trie->accepting)
{
accept1 = trie;
while (accept1->accepting == SIZE_MAX)
accept1 = accept1->fail;
left1 = tp - accept1->depth;
if (left1 <= left)
{
left = left1;
accept = accept1;
}
}
}
}
kwsmatch->index = accept->accepting / 2;
kwsmatch->offset[0] = left - text;
kwsmatch->size[0] = accept->depth;
return left - text;
}
/* Hairy multiple string search with Aho-Corasick algorithm. */
static ptrdiff_t
acexec (kwset_t kwset, char const *text, ptrdiff_t size,
struct kwsmatch *kwsmatch, bool longest)
{
assume (0 <= size);
/* Help the compiler inline in two ways, depending on whether
kwset->trans is null. */
return (IGNORE_DUPLICATE_BRANCH_WARNING
(kwset->trans
? acexec_trans (kwset, text, size, kwsmatch, longest)
: acexec_trans (kwset, text, size, kwsmatch, longest)));
}
/* Find the first instance of a KWSET member in TEXT, which has SIZE bytes.
Return the offset (into TEXT) of the first byte of the matching substring,
or -1 if no match is found. Upon a match, store details in
*KWSMATCH: index of matched keyword, start offset (same as the return
value), and length. If LONGEST, find the longest match; otherwise
any match will do. */
ptrdiff_t
kwsexec (kwset_t kwset, char const *text, ptrdiff_t size,
struct kwsmatch *kwsmatch, bool longest)
{
return kwset->kwsexec (kwset, text, size, kwsmatch, longest);
}
/* Free the components of the given keyword set. */
void
kwsfree (kwset_t kwset)
{
obstack_free (&kwset->obstack, NULL);
free (kwset);
}