Scan character runs in bulk while parsing#490
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`Source.__init__` built `iter([(i, TOMLChar(c)) for i, c in enumerate(self)])`, allocating one tuple and one TOMLChar per character of the whole input up front. Track an integer index into the underlying string instead: `inc()` bumps the index and reads `self[idx]`, and state save/restore snapshots the index rather than copying an iterator. Construction is O(1) and per-character work is deferred to the read. No behaviour change (full suite incl. the toml-test conformance submodule passes); ~1.07-1.14x faster parsing across document sizes.
The parser advanced one character at a time through runs of whitespace, bare-key and number characters, paying a `Source.inc()` call (attribute lookups + a `TOMLChar` build + bounds check) for every character. Add `Source.advance_while(charset)` / `advance_until(stopset)`, which scan the underlying string in a single pass and update the index and current character only once, and use them for the leading-whitespace, bare-key and number/date runs. Same value contract as the `while ... and self.inc()` loops they replace. No behaviour change (full suite incl. the toml-test conformance submodule passes; round-trip output byte-identical on a varied corpus). ~1.05-1.32x faster parsing depending on shape (e.g. ~1.26x on a poetry.lock-like file).
This was referenced Jun 5, 2026
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LGTM, please resolve the conflicts. BTW: we are merging by "squash and merge" so the stacked PR is inconvenient. |
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What
The parser advances one character at a time through runs of whitespace, bare-key and number characters, paying a
Source.inc()call (attribute lookups + aTOMLCharbuild + bounds check) for every character of the run.This adds
Source.advance_while(charset)/advance_until(stopset), which scan the underlying string in a single pass and update the index + current character only once, and uses them for the leading-whitespace, bare-key and number/date runs. They keep the exact value contract of thewhile ... and self.inc()loops they replace (on returncurrentis the first character outside / inside the set, or EOF).Benchmarks
Parsing speedup across document sizes/shapes (median, interleaved A/B vs
master, includes #489):No regression on any shape.
Tests
Full suite passes (972 tests, incl. the toml-test conformance submodule). No public API or behaviour change — round-trip output is byte-identical to
masteron a varied corpus.