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This PR copies over the `pep440-rs` crate at commit `a8303b01ffef6fccfdce562a887f6b110d482ef3` with no modifications. It won't pass CI, but modifications will intentionally be confined to later PRs.
42 lines
2.1 KiB
Markdown
42 lines
2.1 KiB
Markdown
# PEP440 in rust
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A library for python version numbers and specifiers, implementing
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[PEP 440](https://peps.python.org/pep-0440)
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```shell
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pip install pep440_rs
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```
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```python
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from pep440_rs import Version, VersionSpecifier
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assert Version("1.1a1").any_prerelease()
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assert Version("1.1.dev2").any_prerelease()
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assert not Version("1.1").any_prerelease()
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assert VersionSpecifier(">=1.0").contains(Version("1.1a1"))
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assert not VersionSpecifier(">=1.1").contains(Version("1.1a1"))
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assert Version("2.0") in VersionSpecifier("==2")
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```
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Unlike [pypa/packaging](https://github.com/pypa/packaging), this library always matches preleases. To only match final releases, filter with `.any_prelease()` beforehand.
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PEP 440 has a lot of unintuitive features, including:
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* An epoch that you can prefix the version which, e.g. `1!1.2.3`. Lower epoch always means lower
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version (`1.0 <=2!0.1`)
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* post versions, which can be attached to both stable releases and prereleases
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* dev versions, which can be attached to sbpth table releases and prereleases. When attached to a
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prerelease the dev version is ordered just below the normal prerelease, however when attached
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to a stable version, the dev version is sorted before a prereleases
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* prerelease handling is a mess: "Pre-releases of any kind, including developmental releases,
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are implicitly excluded from all version specifiers, unless they are already present on the
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system, explicitly requested by the user, or if the only available version that satisfies
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the version specifier is a pre-release.". This means that we can't say whether a specifier
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matches without also looking at the environment
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* prelease vs. prerelease incl. dev is fuzzy
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* local versions on top of all the others, which are added with a + and have implicitly typed
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string and number segments
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* no semver-caret (`^`), but a pseudo-semver tilde (`~=`)
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* ordering contradicts matching: We have e.g. `1.0+local > 1.0` when sorting,
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but `==1.0` matches `1.0+local`. While the ordering of versions itself is a total order
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the version matching needs to catch all sorts of special cases
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