Do not unnecessarily rescan a string for a literal in a RegExp disjunction #754
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…ction Assume we have the RegExp /<(foo|bar)/ and the input string "<0bar<0bar<0bar". When we try to match the string, we first scan it fully for "foo", but can't find it. Then we scan for "bar" and find it at index 2. However, since there is no '<' right before it, we continue with our search. We currently do the same thing two more times starting at indexes 7 and 12 (since those are where the "bar"s are), each time scanning the rest of the string fully for "foo". However, if we cache the furthest offsets we tried, we can skip the searches for "foo" after the first time.
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| matcher.literalNextSyncInputOffsets = | ||
| RecyclerNewArrayLeaf(matcher.recycler, CharCount, ScannersMixin::MaxNumSyncLiterals); | ||
| } | ||
| CharCount* literalNextSyncInputOffsets = matcher.literalNextSyncInputOffsets; |
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Please add the assert here for numLiterals is lesser than MaxNumSincLiterals.
Rest looks good to me.
chakrabot
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Apr 12, 2016
…RegExp disjunction Merge pull request #754 from goyakin:regexp-literal-scanner-perf
chakrabot
pushed a commit
that referenced
this pull request
Apr 12, 2016
…literal in a RegExp disjunction Merge pull request #754 from goyakin:regexp-literal-scanner-perf
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Assume we have the RegExp /<(foo|bar)/ and the input string "<0bar<0bar<0bar".
When we try to match the string, we first scan it fully for "foo", but can't
find it. Then we scan for "bar" and find it at index 2. However, since there is
no '<' right before it, we continue with our search. We currently do the same
thing two more times starting at indexes 7 and 12 (since those are where the
"bar"s are), each time scanning the rest of the string fully for "foo".
However, if we cache the furthest offsets we tried, we can skip the searches
for "foo" after the first time.
This change has no effect on the general perf.
VSO bug: 4540543
jQuery issue: jquery/jquery#2563