[6.0] Allow captures in lookahead and atomic groups #736
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This fixes an issue where capture groups inside a positive lookahead
were being reset even upon successful matching of the lookahead. For
example, with the pattern `/(?=(\d))/`, matching against a string like
`"abc1"` should result in the output `("", "1")`. However, accessing
the output traps instead, since the range data for capture 1 is
missing even on success.
This change resolves the issue by adding a boolean payload to the
`fail` instruction that indicates whether to preserve captures when
resetting the matching state, which allows any captures inside a
lookahead to persist after success.
Fixes #713.
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@swift-ci Please test |
stephentyrone
approved these changes
Apr 17, 2024
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Explanation: This resolves an issue where matching a pattern that includes a capture group inside a positive lookahead or an atomic group results in a runtime error.
Scope: All the changes are internal implementation within the
_StringProcessingmodule.Issue: rdar://126009544
Original PR: #723
Risk: Low. There's no API or ABI impact of this change.
Testing: This change adds tests that verify that the previously failing patterns are working correctly, and continues to pass the existing compilation and pattern-matching tests.
Reviewer: @stephentyrone
Cherry pick to
swift/release/6.0of #723.