Allow CustomConsuming types to match w/ zero width #479
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We previously asserted if a custom consuming type matches with zero width, but that isn't necessary or good. A custom type can implement a lookaround assertion or act as a tracer.
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@swift-ci Please test |
milseman
reviewed
Jun 14, 2022
| @@ -120,7 +120,7 @@ extension Processor { | |||
| mutating func advance(to nextIndex: Input.Index) { | |||
| assert(nextIndex >= bounds.lowerBound) | |||
| assert(nextIndex <= bounds.upperBound) | |||
| assert(nextIndex > currentPosition) | |||
| assert(nextIndex >= currentPosition) | |||
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Is this the better change, or is it better to not call advance(to:) if there's nowhere to advance to?
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It doesn't seem necessary to require the precondition for this method, given that a zero-width "advance" is a reasonable output for a consumer/other regex component. Would it sound better to you to rename this to continue(at:)?
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I'd prefer changing the name if we're changing the meaning here. That way the call sites are clearer that we're not guaranteeing forward progress (e.g. empty matches)
Since the given index doesn’t need to advance, this name is less misleading.
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@swift-ci Please test |
milseman
reviewed
Jun 17, 2022
| mutating func resume(at index: Input.Index) { | ||
| assert(index >= bounds.lowerBound) | ||
| assert(index <= bounds.upperBound) | ||
| assert(index >= currentPosition) |
milseman
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to milseman/swift-experimental-string-processing
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Jun 30, 2022
* Allow CustomConsuming types to match w/ zero width We previously asserted if a custom consuming type matches with zero width, but that isn't necessary or good. A custom type can implement a lookaround assertion or act as a tracer. * Rename Processor.advance(to:) to resume(at:) Since the given index doesn’t need to advance, this name is less misleading.
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We previously asserted if a custom consuming type matches with zero width, but that isn't necessary or good. A custom type can implement a lookaround assertion or act as a tracer.