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Improve performance

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Removing ANCHORED means that after findIter is unable to find any more matches,
it doesn't bother searching unless there are some promising 0-len matches. This
significantly improves performance on problems like
`"abccccccccccccc".find(re"a")`. Previously, each "c" would require a call to
pcre_exec, which would iterate over [index_of_c..string.len], a O(n^2) process!
This commit is contained in:
Flaviu Tamas
2015-04-12 10:33:21 -04:00
parent 8b8224ecaf
commit 90d17c4e03
1 changed files with 1 additions and 1 deletions
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src/nre.nim
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@@ -489,7 +489,7 @@ iterator findIter*(str: string, pattern: Regex, start = 0, endpos = int.high): R
if match and
match.get.matchBounds.a > match.get.matchBounds.b:
# 0-len match
flags = pcre.NOTEMPTY_ATSTART or pcre.ANCHORED
flags = pcre.NOTEMPTY_ATSTART
match = str.matchImpl(pattern, offset, endpos, flags)