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SF patch #720991 by Gary Herron:

Browse source 
A small fix for bug #545855 and Greg Chapman's
addition of op code SRE_OP_MIN_REPEAT_ONE for
eliminating recursion on simple uses of pattern '*?' on a
long string.
This commit is contained in:
Guido van Rossum 2003-04-14 17:59:34 +00:00
parent 44c62ef5ee
commit 41c99e7f96
7 changed files with 89 additions and 4 deletions
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60
Modules/_sre.c
View file

@ -993,6 +993,66 @@ SRE_MATCH(SRE_STATE* state, SRE_CODE* pattern, int level)
}
return 0;
case SRE_OP_MIN_REPEAT_ONE:
/* match repeated sequence (minimizing regexp) */
/* this operator only works if the repeated item is
exactly one character wide, and we're not already
collecting backtracking points. for other cases,
use the MIN_REPEAT operator */
/* <MIN_REPEAT_ONE> <skip> <1=min> <2=max> item <SUCCESS> tail */
TRACE(("|%p|%p|MIN_REPEAT_ONE %d %d\n", pattern, ptr,
pattern[1], pattern[2]));
if (ptr + pattern[1] > end)
return 0; /* cannot match */
state->ptr = ptr;
if (pattern[1] == 0)
count = 0;
else {
/* count using pattern min as the maximum */
count = SRE_COUNT(state, pattern + 3, pattern[1], level + 1);
if (count < 0)
return count; /* exception */
if (count < (int) pattern[1])
return 0; /* did not match minimum number of times */
ptr += count; /* advance past minimum matches of repeat */
}
if (pattern[pattern[0]] == SRE_OP_SUCCESS) {
/* tail is empty. we're finished */
state->ptr = ptr;
return 1;
} else {
/* general case */
int matchmax = ((int)pattern[2] == 65535);
int c;
lastmark = state->lastmark;
while (matchmax || count <= (int) pattern[2]) {
state->ptr = ptr;
i = SRE_MATCH(state, pattern + pattern[0], level + 1);
if (i)
return i;
state->ptr = ptr;
c = SRE_COUNT(state, pattern+3, 1, level+1);
if (c < 0)
return c;
if (c == 0)
break;
assert(c == 1);
ptr++;
count++;
}
lastmark_restore(state, lastmark);
}
return 0;
case SRE_OP_REPEAT:
/* create repeat context. all the hard work is done
by the UNTIL operator (MAX_UNTIL, MIN_UNTIL) */