Fixing torch version parsing. (#143)

* Fixing torch version parsing.

* Anticipating a bit more variations of this.

bindings/python/src/lib.rs

@@ -446,23 +446,24 @@ impl Version {
         }
     }
 
-    fn from_string(string: String) -> Result<Self, &'static str> {
+    fn from_string(string: &str) -> Result<Self, String> {
         let mut parts = string.split('.');
-        let major_str = parts.next().ok_or("Torch major version missing")?;
-        let minor_str = parts.next().ok_or("Torch minor version missing")?;
-        let patch_str = parts.next().ok_or("Torch path version missing")?;
-        let mut patch_parts = patch_str.split('+');
-        let patch_str = patch_parts.next().ok_or("Torch path version missing")?;
-
-        let major = major_str
-            .parse()
-            .map_err(|_| "Python major version not an integer")?;
-        let minor = minor_str
-            .parse()
-            .map_err(|_| "Python minor version not an integer")?;
-        let patch = patch_str
-            .parse()
-            .map_err(|_| "Python patch version not an integer")?;
+        let err = || format!("Could not parse torch package version {string}.");
+        let major_str = parts.next().ok_or_else(err)?;
+        let minor_str = parts.next().ok_or_else(err)?;
+        let patch_str = parts.next().ok_or_else(err)?;
+        // Patch is more complex and can be:
+        // - `1` a number
+        // - `1a0`, `1b0`, `1rc1` an alpha, beta, release candidate version
+        // - `1a0+git2323` from source with commit number
+        let patch_str: String = patch_str
+            .chars()
+            .take_while(|c| c.is_ascii_digit())
+            .collect();
+
+        let major = major_str.parse().map_err(|_| err())?;
+        let minor = minor_str.parse().map_err(|_| err())?;
+        let patch = patch_str.parse().map_err(|_| err())?;
         Ok(Version {
             major,
             minor,
@@ -542,7 +543,7 @@ impl safe_open {
 
                 let version: String = module.getattr(intern!(py, "__version__"))?.extract()?;
                 let version =
-                    Version::from_string(version).map_err(exceptions::PyException::new_err)?;
+                    Version::from_string(&version).map_err(exceptions::PyException::new_err)?;
 
                 // Untyped storage only exists for versions over 1.11.0
                 // Same for torch.asarray which is necessary for zero-copy tensor
@@ -1028,3 +1029,23 @@ fn safetensors_rust(_py: Python, m: &PyModule) -> PyResult<()> {
     m.add_class::<safe_open>()?;
     Ok(())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn version_parse() {
+        let torch_version = "1.1.1";
+        let version = Version::from_string(torch_version).unwrap();
+        assert_eq!(version, Version::new(1, 1, 1));
+
+        let torch_version = "2.0.0a0+gitd1123c9";
+        let version = Version::from_string(torch_version).unwrap();
+        assert_eq!(version, Version::new(2, 0, 0));
+
+        let torch_version = "something";
+        let version = Version::from_string(torch_version);
+        assert!(version.is_err());
+    }
+}