Support parsing python pre-release versions (#3)

* Support parsing python pre-release versions

* another python version format

* dont error on epipe (#2)

* dont error on epipe

* formatted

* Add docs and reduce to a single python regex

* formatting

* remove only flag

* more python version tests

* update docs

Author: justinmchase

src/parse.test.ts

@@ -42,3 +42,22 @@ Deno.test({
     assertEquals(parse(v), v);
   },
 });
+
+const pythonVersions = [
+  ["0.13.1a0", "0.13.1-a.0"],
+  ["0.13.1b0", "0.13.1-b.0"],
+  ["0.13.1rc0", "0.13.1-rc.0"],
+  ["0.13.1.dev0", "0.13.1-dev.0"],
+  ["0.13.1.post0", "0.13.1-post.0"],
+];
+
+for (let i = 0; i < pythonVersions.length; i++) {
+  const [input, expected] = pythonVersions[i];
+  Deno.test({
+    name: `PY${i.toString().padStart(2, "0")}`,
+    fn: () => {
+      const v = parse(input);
+      assertEquals(v.toString(), expected);
+    },
+  });
+}

src/parse.ts

@@ -5,7 +5,29 @@ export function parse(version: Version): SemVer {
   if (version instanceof semver.SemVer) {
     return version;
   }
-  const versionString = version.toString();
+  let versionString = version.toString().trim();
+
+  // Python version documentation:
+  // https://peps.python.org/pep-0440/#public-version-identifiers
+  //
+  // supports converting _most_ python versions into common semver
+  // [N!]N(.N)*[{a|b|rc}N][.postN][.devN]
+  //
+  // | example      | result        |
+  // | ------------ | ------------- |
+  // | 0.13.1a0     | 0.13.1-a.0    |
+  // | 0.13.1b0     | 0.13.1-b.0    |
+  // | 0.13.1rc0    | 0.13.1-rc.0   |
+  // | 0.13.1.dev0  | 0.13.1-dev.0  |
+  // | 0.13.1.post0 | 0.13.1-post.0 |
+  //
+  const py = versionString.match(
+    /^(\d+)[.](\d+)[.](\d+)[.]?(a|b|rc|dev|post)(\d+)$/,
+  );
+  if (py) {
+    const [, major, minor, patch, pre, dev] = py;
+    versionString = `${major}.${minor}.${patch}-${pre}.${dev}`;
+  }
 
   // supports converting partial versions such as 1, 1.0 into valid semantic versions.
   const parsed = semver.parse(versionString) ??