feat: add immutable field slice iter

1 files changed, 65 insertions, 1 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 9e25467..fc7179d 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -245,7 +245,11 @@ impl MultiVec
             )
         };
 
-        FieldSlice { bytes, field_metadata }
+        FieldSlice {
+            bytes,
+            len: self.len(),
+            field_metadata,
+        }
     }
 
     /// Returns a slice containing the specified field of all items.
@@ -485,6 +489,7 @@ impl Drop for MultiVec
 pub struct FieldSlice<'mv>
 {
     bytes: &'mv [MaybeUninit<u8>],
+    len: usize,
     field_metadata: &'mv FieldMetadata,
 }
 
@@ -496,6 +501,65 @@ impl FieldSlice<'_>
 
         unsafe { self.bytes.cast::<Item>() }
     }
+
+    pub fn iter(&self) -> FieldSliceIter<'_>
+    {
+        FieldSliceIter {
+            bytes: self.bytes,
+            index: 0,
+            len: self.len,
+            field_metadata: self.field_metadata,
+        }
+    }
+}
+
+pub struct FieldSliceIter<'mv>
+{
+    bytes: &'mv [MaybeUninit<u8>],
+    index: usize,
+    len: usize,
+    field_metadata: &'mv FieldMetadata,
+}
+
+impl<'mv> Iterator for FieldSliceIter<'mv>
+{
+    type Item = Field<'mv>;
+
+    fn next(&mut self) -> Option<Self::Item>
+    {
+        let start_off = self.index * self.field_metadata.size;
+
+        if self.index >= self.len {
+            return None;
+        }
+
+        let field_bytes = self
+            .bytes
+            .get(start_off..start_off + self.field_metadata.size)?;
+
+        self.index += 1;
+
+        Some(Field {
+            bytes: field_bytes,
+            field_metadata: self.field_metadata,
+        })
+    }
+}
+
+pub struct Field<'mv>
+{
+    bytes: &'mv [MaybeUninit<u8>],
+    field_metadata: &'mv FieldMetadata,
+}
+
+impl Field<'_>
+{
+    pub fn cast<T: 'static>(&mut self) -> &T
+    {
+        assert_eq!(TypeId::of::<T>(), self.field_metadata.type_id);
+
+        unsafe { &*self.bytes.as_ptr().cast::<T>() }
+    }
 }
 
 pub struct FieldSliceMut<'mv>