[GitHub] [arrow-rs] Weijun-H commented on a diff in pull request #4042: feat: DataType::contains support nested type

["Weijun-H (via GitHub)" <gi...@apache.org>]

Weijun-H commented on code in PR #4042:
URL: https://github.com/apache/arrow-rs/pull/4042#discussion_r1161735624


##########
arrow-schema/src/datatype.rs:
##########
@@ -498,6 +498,29 @@ impl DataType {
                 }
             }
     }
+
+    /// Check to see if `self` is a superset of `other`
+    ///
+    /// If DataType is a nested type, then it will check to see if the nested type is a superset of the other nested type
+    /// else it will check to see if the DataType is equal to the other DataType
+    pub fn contains(&self, other: &DataType) -> bool {
+        match self {
+            DataType::List(field)
+            | DataType::LargeList(field)
+            | DataType::Map(field, _)
+            | DataType::FixedSizeList(field, _) => field.data_type().contains(other),

Review Comment:
   I would like to further clarify the definition of 'contain' through testing. Are the following tests accurate for this purpose?
   ``` rust
       #[test]
       fn test_contains_nested_field() {
           let child_field1 = Field::new("child1", DataType::Float16, false);
           let child_field2 = Field::new("child2", DataType::Float16, false);
   
           let field1 = Field::new(
               "field1",
               DataType::Struct(vec![child_field1.clone()].into()),
               true,
           );
           let field2 = Field::new(
               "field1",
               DataType::Struct(vec![child_field1, child_field2].into()),
               true,
           );
   
           assert!(field2.contains(&field1));
           assert!(!field1.contains(&field2));
       }
   ```



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