perf: short-circuit IsMatcher on the first match#559
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IsMatcher handled multi-node selections by calling m.Filter(s.Nodes) and checking whether the returned slice was non-empty, forcing the matcher to walk the whole selection and materialize all matches even though the API only needs an existence check. This commit replaces this with a simple loop over s.Nodes that calls m.Match(n) and returns true on the first match. This also makes the single-node special case unnecessary. Benchmark results on arm64 over 10 runs: name old time/op new time/op delta Is-8 4.67µs 1.32µs -71.7% IsPositional-8 21.44µs 0.82µs -96.2% name old B/op new B/op delta Is-8 96 80 -16.7% IsPositional-8 1144 184 -83.9% name old allocs new allocs delta Is-8 5 4 -20.0% IsPositional-8 11 7 -36.4%
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IsMatcher handled multi-node selections by calling m.Filter(s.Nodes) and checking whether the returned slice was non-empty, forcing the matcher to walk the whole selection and materialize all matches even though the API only needs an existence check.
This commit replaces this with a simple loop over s.Nodes that calls m.Match(n) and returns true on the first match. This also makes the single-node special case unnecessary.
Benchmark results on arm64 over 10 runs:
name old time/op new time/op delta
Is-8 4.67µs 1.32µs -71.7%
IsPositional-8 21.44µs 0.82µs -96.2%
name old B/op new B/op delta
Is-8 96 80 -16.7%
IsPositional-8 1144 184 -83.9%
name old allocs new allocs delta
Is-8 5 4 -20.0%
IsPositional-8 11 7 -36.4%