Avoid a clone when creating MapArray from ArrayData

Author: alamb

arrow-array/src/array/map_array.rs

@@ -272,28 +272,29 @@ impl From<MapArray> for ArrayData {
 
 impl MapArray {
     fn try_new_from_array_data(data: ArrayData) -> Result<Self, ArrowError> {
-        if !matches!(data.data_type(), DataType::Map(_, _)) {
+        let (data_type, len, nulls, offset, mut buffers, mut child_data) = data.into_parts();
+
+        if !matches!(data_type, DataType::Map(_, _)) {
             return Err(ArrowError::InvalidArgumentError(format!(
-                "MapArray expected ArrayData with DataType::Map got {}",
-                data.data_type()
+                "MapArray expected ArrayData with DataType::Map got {data_type}",
             )));
         }
 
-        if data.buffers().len() != 1 {
+        if buffers.len() != 1 {
             return Err(ArrowError::InvalidArgumentError(format!(
                 "MapArray data should contain a single buffer only (value offsets), had {}",
-                data.len()
+                buffers.len(),
             )));
         }
+        let buffer = buffers.pop().expect("checked above");
 
-        if data.child_data().len() != 1 {
+        if child_data.len() != 1 {
             return Err(ArrowError::InvalidArgumentError(format!(
                 "MapArray should contain a single child array (values array), had {}",
-                data.child_data().len()
+                child_data.len()
             )));
         }
-
-        let entries = data.child_data()[0].clone();
+        let entries = child_data.pop().expect("checked above");
 
         if let DataType::Struct(fields) = entries.data_type() {
             if fields.len() != 2 {
@@ -312,11 +313,11 @@ impl MapArray {
 
         // SAFETY:
         // ArrayData is valid, and verified type above
-        let value_offsets = unsafe { get_offsets(&data) };
+        let value_offsets = unsafe { get_offsets(buffer, offset, len) };
 
         Ok(Self {
-            data_type: data.data_type().clone(),
-            nulls: data.nulls().cloned(),
+            data_type,
+            nulls,
             entries,
             value_offsets,
         })