Add convenience methods to StringScanner
#16595
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jneen
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jneen
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I think the spec failure here is a flapper, it is a TCP error unrelated to the change. |
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January 22, 2026 09:33
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jneen
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January 24, 2026 09:06
…s only an issue for nonzero indices
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Updated docs. Also realized there's a subtle footgun with |
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And yeah having played around with it for a bit, I think this is a tricky enough issue to warrant removing |
straight-shoota
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Jan 26, 2026
ysbaddaden
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Jan 27, 2026
straight-shoota
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StringScanner
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Depends on #16557.Extracted from #16455.
Fixes #11259, with the exception of the methods that mutate the string.
Rationale
Ruby's comparable StringScanner library provides a number of extra convenience methods. I've gone through the list and implemented/specced the ones that make sense here.
Changes
#matched? : Boolto check for the presence of@last_match#current_char : Char,#previous_char : Charas well as nilable variants#current_byte : UInt8,#previous_byte : UInt8, as well as nilable variants#beginning_of_line?I believe originally conceived because anchors like^were non-functional in Ruby due to a bug in their implementation - not an issue in Crystal. It is generally a useful method though, and I couldn't see an argument against including it.#rewind(Int)to move the scan head backwards manually#unscanfor rewinding to the start of the previous scan#checkand#scan_until. Will open a separate PR for it later.