Parse Oniguruma callout and absent function syntax #129
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| @@ -185,6 +188,43 @@ extension AST { | |||
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| } | |||
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| public struct AbsentFunction: Hashable, _ASTNode { | |||
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I know Oniguruma uses this "absent function" name, but is there a better or more descriptive name? What does this do?
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Hmm, its primary role it to match against an inverse of a pattern (though the .expression variant also specifies what it can match). So maybe something like MatchInverse or Exclusion?
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Ah, I see. This is Oniguruma's approach to the regex-inversion problem (i.e. inverting each component of a concatenation is surprising and not the same as inverting the regex). I'm fine keeping this name with a comment for now, as a term-of-art or something to be renamed later.
@rxwei any thoughts on how to model pattern inversions in the DSL?
| ) -> Located<AST.AbsentFunction.Start>? { | ||
| recordLoc { src in | ||
| if src.tryEat(sequence: "(?~|") { return .withPipe } | ||
| if src.tryEat(sequence: "(?~") { return .withoutPipe } |
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Is there a more descriptive name than "with(out) pipe"?
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I mean withoutPipe is only used for the repeater syntax, so we could call it repeater? And withPipe could maybe be normal or something?
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I think Oniguruma calls them repeater and stopper, which sounds good enough to me for now.
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Note this is just for the opening syntax, (?~| is not just for absent stoppers, but also for absent expressions and clearers.
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I've left the naming as-is for now, but am happy to change in a follow-up
Previously we just silently stopped parsing at these due to them being a termination condition for recursive parsing. Pick them up and diagnose when not doing a recursive parse.
Parse named and 'of-contents' Oniguruma callouts. This requires generalizing the group name handling to be for arbitrary identifiers, which may have a specific kind for diagnostics.
Parse the 4 varieties of absent function syntax supported by Oniguruma.
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@swift-ci please test Linux |
Parse both variants of Oniguruma callout syntax
(*name[tag]{args, ...})and(?{...}[]), as well as Oniguruma absent functions(?~|). In addition, diagnose ending)s that don't close any groups.