Bug 258531

Summary: [JSC] Improve RegExp Lookbehind Character Class Backtracking
Product: WebKit Reporter: Michael Saboff <msaboff>
Component: JavaScriptCoreAssignee: Michael Saboff <msaboff>
Status: RESOLVED FIXED    
Severity: Normal CC: webkit-bug-importer
Priority: P2 Keywords: InRadar
Version: WebKit Local Build   
Hardware: Unspecified   
OS: Unspecified   

Description Michael Saboff 2023-06-26 14:06:15 PDT 
We currently backtrack character classes that may contain non-BMP characters by rematching one less than the prior count.  For large strings that need to backtrack a large number of characters, this is quit wasteful.

Now that we have methods that can read non-BMP characters either forward or bacckward, we can use these to back up just one character.  The same applies to lookaheads.
Comment 1 Michael Saboff 2023-06-26 14:06:46 PDT 
<rdar://111051833>
Comment 2 Michael Saboff 2023-06-26 14:20:04 PDT 
Pull request: https://github.com/WebKit/WebKit/pull/15304
Comment 3 EWS 2023-06-28 12:42:08 PDT 
Committed 265593@main (8e5b3f5761f0): <https://commits.webkit.org/265593@main>

Reviewed commits have been landed. Closing PR #15304 and removing active labels.