[mypyc] Add librt.strings.isspace char primitive#21462
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Adds a codepoint-taking `librt.strings.isspace(c: i32) -> bool` that wraps `Py_UNICODE_ISSPACE`. Combined with the existing `ord(s[i])` specialization (python#20578), this lets per-character hot loops avoid the 1-character `PyUnicode` materialization that `s[i].isspace()` forces. Microbenchmark (counting whitespace in a 12 KB SQL fragment, 5000 iterations): mypyc-compiled `s[i].isspace()` takes 0.075 ms; the codepoint path `c: i32 = i32(ord(s[i])); isspace(c)` takes 0.034 ms, roughly 2.2x faster. Wins compound for tokenizer-shaped workloads mixing classification and literal compares.
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According to mypy_primer, this change doesn't affect type check results on a corpus of open source code. ✅ |
Without the _librt suffix, has_test_name_tag returns False and the test imports the installed PyPI librt 0.11.0, which lacks isspace.
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This PR serves as the foundation for the smaller alternative of the
charproposal request.It builds on top of the existing
librt.stringsandord(char)specialization, so code like the following can lower to a direct codepoint check i.e without materializing a 1-character str:Semantics:
i32Falsestr.isspace()on the corresponding 1-character string (ensured by exhaustive test too)This PR adds only
isspace; It does not add any new type-system surface, and it does not introduce the rest of the codepoint helperfamily. I'll be contributing these next if this direction looks good.