Upgrade to Syn 0.15 #19
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lukaslueg
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Oct 16, 2018
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| impl Parse for Repetition { | ||
| fn parse(input: ParseStream) -> Result<Self> { | ||
| if input.parse::<Option<Token![*]>>()?.is_some() { |
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My spider senses are tickling here: IIRC there is a change in the 2018 edition in order to disambiguate repetition markers from separators. Maybe we will need a knob here in the future?
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Yep, you're thinking of rust-lang/rust#51934. What I implemented is the 2018 behavior. Using ? as a repetition separator in 2015 would be so unusual that I wouldn't worry about it in this library.
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Some ideas for how I would implement the Syn upgrade. I am going to be busy for the rest of the week so feel free to take any ideas from here and incorporate into #18 as makes sense.
#18 mentioned a performance degradation -- I added a benchmark and found that this PR improves parsing performance by about 20% compared to Syn 0.14. You can confirm by running
cargo benchagainst the first commit which just adds the benchmark, and against the second commit which contains the 0.15 code.