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(re_search_2): Optimize regexp that starts with ^.

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Richard M. Stallman 1996-08-31 23:40:19 +00:00
parent 590027f762
commit c8499ba5d8
1 changed files with 19 additions and 1 deletions
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20
src/regex.c
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@ -3284,6 +3284,7 @@ re_search_2 (bufp, string1, size1, string2, size2, startpos, range, regs, stop)
register RE_TRANSLATE_TYPE translate = bufp->translate;
int total_size = size1 + size2;
int endpos = startpos + range;
int anchored_start = 0;
/* Check for out-of-range STARTPOS. */
if (startpos < 0 || startpos > total_size)
@ -3323,9 +3324,26 @@ re_search_2 (bufp, string1, size1, string2, size2, startpos, range, regs, stop)
if (re_compile_fastmap (bufp) == -2)
return -2;
/* See whether the pattern is anchored. */
if (bufp->buffer[0] == begline)
anchored_start = 1;
/* Loop through the string, looking for a place to start matching. */
for (;;)
{
/* If the pattern is anchored,
skip quickly past places we cannot match.
We don't bother to treat startpos == 0 specially
because that case doesn't repeat. */
if (anchored_start && startpos > 0)
{
if (! (bufp->newline_anchor
&& ((startpos <= size1 ? string1[startpos - 1]
: string2[startpos - size1 - 1])
== '\n')))
goto advance;
}
/* If a fastmap is supplied, skip quickly over characters that
cannot be the start of a match. If the pattern can match the
null string, however, we don't need to skip characters; we want
@ -3461,7 +3479,7 @@ static boolean alt_match_null_string_p (),
/* Free everything we malloc. */
#ifdef MATCH_MAY_ALLOCATE
#define FREE_VAR(var) if (var) then { REGEX_FREE (var); var = NULL; } else
#define FREE_VAR(var) if (var) { REGEX_FREE (var); var = NULL; } else
#define FREE_VARIABLES() \
do { \
REGEX_FREE_STACK (fail_stack.stack); \