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This adds the ability to add a label to a repeat range so that a subsequent expression can match the same repetition. This is intended to help with expressing things like raw strings where the `#` characters must be balanced on both sides, with a limit on the number of matches.
This changes the raw string grammars to use named repetition to represent that the `#` characters need to be balanced within a specific limit. This also adds a cut after the `#` and before the `"` because rustc generates an error in this situation if a `"` is not found. It's maybe not the prettiest, and I'm on the fence whether this makes it clearer.
These non-greedy repetitions are no longer needed because we now use negative lookahead in the rules that were using them. This is intended to simplify things a little, and lean in on the negative lookahead. There were two alternate interpretations of `R1 -> A E*? S B`: R1 -> A _0 B _0 -> S | (E _0) or R1 -> A _0 _0 -> (S B) | (E _0) Rather than trying to document this subtle interpretation, this chooses to just get rid of it and be explicit about what is not allowed to follow.
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This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed. Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers. |
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This adds the ability to add a label to a repeat range so that a subsequent expression can match the same repetition. This is used in raw strings where the
#characters must be balanced on both sides, with a limit on the number of matches.This also removes the non-greedy repetitions because they are no longer used.