Normalize map types on creation

CurtHagenlocher · Dec 11, 2023 · 03ba59f · 03ba59f
1 parent ee8fe2f
commit 03ba59f
Showing 1 changed file with 44 additions and 4 deletions.
diff --git a/csharp/src/Apache.Arrow/Types/MapType.cs b/csharp/src/Apache.Arrow/Types/MapType.cs
@@ -13,12 +13,17 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+using System;
 using System.Collections.Generic;
 
 namespace Apache.Arrow.Types
 {
     public sealed class MapType : NestedType // MapType = ListType(StructType("key", "value")) 
     {
+        private const string EntriesKey = "entries";
+        private const string KeyKey = "key";
+        private const string ValueKey = "value";
+
         public override ArrowTypeId TypeId => ArrowTypeId.Map;
         public override string Name => "map";
         public readonly bool KeySorted;
@@ -28,20 +33,23 @@ public sealed class MapType : NestedType // MapType = ListType(StructType("key",
         public Field ValueField => KeyValueType.Fields[1];
 
         public MapType(IArrowType key, IArrowType value, bool nullable = true, bool keySorted = false)
-            : this(new Field("key", key, false), new Field("value", value, nullable), keySorted)
+            : base(Entries(key, value, nullable))
         {
+            KeySorted = keySorted;
         }
 
         public MapType(Field key, Field value, bool keySorted = false)
-            : this(new StructType(new List<Field>() { key, value }), keySorted)
+            : base(Entries(key, value))
         {
+            KeySorted = keySorted;
         }
 
-        public MapType(StructType entries, bool keySorted = false) : this(new Field("entries", entries, false), keySorted)
+        public MapType(StructType entries, bool keySorted = false) : base(Entries(entries))
         {
+            KeySorted = keySorted;
         }
 
-        public MapType(Field entries, bool keySorted = false) : base(entries)
+        public MapType(Field entries, bool keySorted = false) : base(Entries(entries))
         {
             KeySorted = keySorted;
         }
@@ -54,5 +62,37 @@ public MapType UnsortedKey()
 
             return new MapType(Fields[0], keySorted: false);
         }
+
+        private static Field Entries(IArrowType key, IArrowType value, bool nullable) =>
+            new Field(EntriesKey, NewStruct(new Field(KeyKey, key, false), new Field(ValueKey, value, nullable)), false);
+
+        private static Field Entries(Field key, Field value) =>
+            new Field(EntriesKey, NewStruct(NamedField(KeyKey, key), NamedField(ValueKey, value)), false);
+
+        private static Field Entries(StructType entries)
+        {
+            return new Field(EntriesKey, Struct(entries), false);
+        }
+
+        private static StructType NewStruct(Field key, Field value) => new StructType(new[] { key, value });
+
+        private static StructType Struct(StructType entries)
+        {
+            Field key = NamedField(KeyKey, entries.Fields[0]);
+            Field value = NamedField(ValueKey, entries.Fields[1]);
+            return object.ReferenceEquals(key, entries.Fields[0]) && object.ReferenceEquals(value, entries.Fields[1]) ? entries : NewStruct(key, value);
+        }
+
+        private static Field Entries(Field entries)
+        {
+            StructType structType = (StructType)entries.DataType;
+            StructType adjustedStruct = Struct(structType);
+            return StringComparer.Ordinal.Equals(entries.Name, EntriesKey) && object.ReferenceEquals(structType, adjustedStruct) ? entries : new Field(EntriesKey, adjustedStruct, false);
+        }
+
+        private static Field NamedField(string name, Field field)
+        {
+            return StringComparer.Ordinal.Equals(name, field.Name) ? field : new Field(name, field.DataType, field.IsNullable, field.Metadata);
+        }
     }
 }