Implement Iterator interfaces for LoadedValueIterator

array_iterator.go

@@ -228,6 +228,8 @@ type ArrayLoadedValueIterator struct {
 	dataIterator *arrayLoadedElementIterator
 }
 
+var _ ArrayIterator = &ArrayLoadedValueIterator{}
+
 func (i *ArrayLoadedValueIterator) nextDataIterator() (*arrayLoadedElementIterator, error) {
 
 	// Iterate parents (LIFO) to find next loaded array data slab.
@@ -268,6 +270,11 @@ func (i *ArrayLoadedValueIterator) nextDataIterator() (*arrayLoadedElementIterat
 	return nil, nil
 }
 
+// CanMutate returns false.
+func (i *ArrayLoadedValueIterator) CanMutate() bool {
+	return false
+}
+
 // Next iterates and returns next loaded element.
 // It returns nil Value at end of loaded elements.
 func (i *ArrayLoadedValueIterator) Next() (Value, error) {

array_test.go

@@ -6326,8 +6326,32 @@ func createArrayWithSimpleAndChildArrayValues(
 }
 
 func testArrayLoadedElements(t *testing.T, array *atree.Array, expectedValues testutils.ExpectedArrayValue) {
+	// Test Next
+
+	iter, err := array.ReadOnlyLoadedValueIterator()
+	require.NoError(t, err)
+	require.False(t, iter.CanMutate())
+
 	i := 0
-	err := array.IterateReadOnlyLoadedValues(func(v atree.Value) (bool, error) {
+	for {
+		v, err := iter.Next()
+		require.NoError(t, err)
+
+		if v == nil {
+			break
+		}
+
+		require.True(t, i < len(expectedValues))
+		testValueEqual(t, expectedValues[i], v)
+
+		i++
+	}
+	require.Equal(t, len(expectedValues), i)
+
+	// Test callback
+
+	i = 0
+	err = array.IterateReadOnlyLoadedValues(func(v atree.Value) (bool, error) {
 		require.True(t, i < len(expectedValues))
 		testValueEqual(t, expectedValues[i], v)
 		i++

map_iterator.go

@@ -506,6 +506,8 @@ type MapLoadedValueIterator struct {
 	dataIterator *mapLoadedElementIterator
 }
 
+var _ MapIterator = &MapLoadedValueIterator{}
+
 func (i *MapLoadedValueIterator) nextDataIterator() (*mapLoadedElementIterator, error) {
 
 	// Iterate parents (LIFO) to find next loaded map data slab.
@@ -546,6 +548,25 @@ func (i *MapLoadedValueIterator) nextDataIterator() (*mapLoadedElementIterator,
 	return nil, nil
 }
 
+// CanMutate returns false.
+func (i *MapLoadedValueIterator) CanMutate() bool {
+	return false
+}
+
+// NextKey iterates and returns next loaded key.
+// It returns nil key at end of loaded elements.
+func (i *MapLoadedValueIterator) NextKey() (Value, error) {
+	key, _, err := i.Next()
+	return key, err
+}
+
+// NextValue iterates and returns next loaded value.
+// It returns nil Value at end of loaded elements.
+func (i *MapLoadedValueIterator) NextValue() (Value, error) {
+	_, value, err := i.Next()
+	return value, err
+}
+
 // Next iterates and returns next loaded element.
 // It returns nil Value at end of loaded elements.
 func (i *MapLoadedValueIterator) Next() (Value, Value, error) {

map_test.go

@@ -16668,8 +16668,74 @@ func createMapWithSimpleAndChildArrayValues(
 }
 
 func testMapLoadedElements(t *testing.T, m *atree.OrderedMap, expectedValues [][2]atree.Value) {
+	// Test NextKey
+	iter, err := m.ReadOnlyLoadedValueIterator()
+	require.NoError(t, err)
+	require.False(t, iter.CanMutate())
+
 	i := 0
-	err := m.IterateReadOnlyLoadedValues(func(k atree.Value, v atree.Value) (bool, error) {
+	for {
+		k, err := iter.NextKey()
+		require.NoError(t, err)
+
+		if k == nil {
+			break
+		}
+
+		require.True(t, i < len(expectedValues))
+		testValueEqual(t, expectedValues[i][0], k)
+
+		i++
+	}
+	require.Equal(t, len(expectedValues), i)
+
+	// Test NextValue
+
+	iter, err = m.ReadOnlyLoadedValueIterator()
+	require.NoError(t, err)
+
+	i = 0
+	for {
+		v, err := iter.NextValue()
+		require.NoError(t, err)
+
+		if v == nil {
+			break
+		}
+
+		require.True(t, i < len(expectedValues))
+		testValueEqual(t, expectedValues[i][1], v)
+
+		i++
+	}
+	require.Equal(t, len(expectedValues), i)
+
+	// Test Next
+
+	iter, err = m.ReadOnlyLoadedValueIterator()
+	require.NoError(t, err)
+
+	i = 0
+	for {
+		k, v, err := iter.Next()
+		require.NoError(t, err)
+
+		if v == nil {
+			break
+		}
+
+		require.True(t, i < len(expectedValues))
+		testValueEqual(t, expectedValues[i][0], k)
+		testValueEqual(t, expectedValues[i][1], v)
+
+		i++
+	}
+	require.Equal(t, len(expectedValues), i)
+
+	// Test callback
+
+	i = 0
+	err = m.IterateReadOnlyLoadedValues(func(k atree.Value, v atree.Value) (bool, error) {
 		require.True(t, i < len(expectedValues))
 		testValueEqual(t, expectedValues[i][0], k)
 		testValueEqual(t, expectedValues[i][1], v)