fix lifetimes, add tensors iterator (#518)

* fix lifetimes, add tensors iterator

* add test for lifetimes

safetensors/src/tensor.rs

@@ -345,10 +345,10 @@ impl<'data> SafeTensors<'data> {
         Ok(Self { metadata, data })
     }
 
-    /// Allow the user to iterate over tensors within the SafeTensors.
+    /// Returns the tensors contained within the SafeTensors.
     /// The tensors returned are merely views and the data is not owned by this
     /// structure.
-    pub fn tensors(&self) -> Vec<(String, TensorView<'_>)> {
+    pub fn tensors(&self) -> Vec<(String, TensorView<'data>)> {
         let mut tensors = Vec::with_capacity(self.metadata.index_map.len());
         for (name, &index) in &self.metadata.index_map {
             let info = &self.metadata.tensors[index];
@@ -362,10 +362,24 @@ impl<'data> SafeTensors<'data> {
         tensors
     }
 
+    /// Returns an iterator over the tensors contained within the SafeTensors.
+    /// The tensors returned are merely views and the data is not owned by this
+    /// structure.
+    pub fn iter<'a>(&'a self) -> impl Iterator<Item = (&'a str, TensorView<'data>)> {
+        self.metadata.index_map.iter().map(|(name, &idx)| {
+            let info = &self.metadata.tensors[idx];
+            (name.as_str(), TensorView {
+                dtype: info.dtype,
+                shape: info.shape.clone(),
+                data: &self.data[info.data_offsets.0..info.data_offsets.1],
+            })
+        })
+    }
+
     /// Allow the user to get a specific tensor within the SafeTensors.
     /// The tensor returned is merely a view and the data is not owned by this
     /// structure.
-    pub fn tensor(&self, tensor_name: &str) -> Result<TensorView<'_>, SafeTensorError> {
+    pub fn tensor(&self, tensor_name: &str) -> Result<TensorView<'data>, SafeTensorError> {
         if let Some(index) = &self.metadata.index_map.get(tensor_name) {
             if let Some(info) = &self.metadata.tensors.get(**index) {
                 Ok(TensorView {
@@ -541,7 +555,7 @@ impl Metadata {
 /// A view of a Tensor within the file.
 /// Contains references to data within the full byte-buffer
 /// And is thus a readable view of a single tensor
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Debug, PartialEq, Eq, Clone)]
 pub struct TensorView<'data> {
     dtype: Dtype,
     shape: Vec<usize>,
@@ -1038,6 +1052,21 @@ mod tests {
         assert_eq!(tensor.data(), b"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
     }
 
+    #[test]
+    fn test_lifetimes() {
+        let serialized = b"<\x00\x00\x00\x00\x00\x00\x00{\"test\":{\"dtype\":\"I32\",\"shape\":[2,2],\"data_offsets\":[0,16]}}\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00";
+
+        let tensor = {
+            let loaded = SafeTensors::deserialize(serialized).unwrap();
+            loaded.tensor("test").unwrap()
+        };
+
+        assert_eq!(tensor.shape(), vec![2, 2]);
+        assert_eq!(tensor.dtype(), Dtype::I32);
+        // 16 bytes
+        assert_eq!(tensor.data(), b"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0");
+    }
+
     #[test]
     fn test_json_attack() {
         let mut tensors = HashMap::new();