feat(corelib): range IndexView

corelib/src/array.cairo

@@ -300,6 +300,14 @@ impl ArrayIndex<T> of IndexView<Array<T>, usize, @T> {
     }
 }
 
+impl ArraySliceIndex<T> of core::ops::IndexView<Array<T>, core::ops::Range<usize>> {
+    type Target = Span<T>;
+
+    fn index(self: @Array<T>, index: core::ops::Range<usize>) -> Span<T> {
+        self.span()[index]
+    }
+}
+
 impl ArraySerde<T, +Serde<T>, +Drop<T>> of Serde<Array<T>> {
     /// Serializes an `Array<T>` into an `Array<felt252>`.
     ///
@@ -635,6 +643,15 @@ pub impl SpanIndex<T> of IndexView<Span<T>, usize, @T> {
     }
 }
 
+impl SpanSliceIndex<T> of core::ops::IndexView<Span<T>, core::ops::Range<usize>> {
+    type Target = Span<T>;
+
+    #[inline]
+    fn index(self: @Span<T>, index: core::ops::Range<usize>) -> Span<T> {
+        (*self).slice(index.start, index.end - index.start)
+    }
+}
+
 /// `ToSpanTrait` converts a data structure into a span of its data.
 pub trait ToSpanTrait<C, T> {
     /// Returns a span pointing to the data in the input.

corelib/src/test/array_test.cairo

@@ -12,14 +12,14 @@ fn test_array() {
 #[should_panic]
 fn test_array_out_of_bound_1() {
     let arr = array![10, 11, 12];
-    arr[3];
+    arr[3_usize];
 }
 
 #[test]
 #[should_panic]
 fn test_array_out_of_bound_2() {
     let arr = array![10, 11, 12];
-    arr[11];
+    arr[11_usize];
 }
 
 #[test]
@@ -215,6 +215,7 @@ fn test_array_snap_into_span() {
 fn test_span_into_array_snap() {
     assert_eq!(@array![1, 2, 3], array![1, 2, 3].span().into());
 }
+
 #[test]
 fn nested_for_loop() {
     let mat = array![array![1, 2], array![3, 4], array![5, 6]];
@@ -226,3 +227,15 @@ fn nested_for_loop() {
     };
     assert_eq!(result, 21);
 }
+
+#[test]
+fn test_array_slice_index() {
+    let arr = array![1, 2, 3, 4, 5];
+    assert!(arr[2_usize..4] == [3, 4].span());
+}
+
+#[test]
+fn test_span_slice_index() {
+    let span = [1, 2, 3, 4, 5].span();
+    assert!(span[2_usize..4] == [3, 4].span());
+}