1 files changed, 96 insertions, 0 deletions
diff --git a/src/arrow/csharp/src/Apache.Arrow/Ipc/ArrowFooter.cs b/src/arrow/csharp/src/Apache.Arrow/Ipc/ArrowFooter.cs
new file mode 100644
index 000000000..db269ae01
--- /dev/null
+++ b/src/arrow/csharp/src/Apache.Arrow/Ipc/ArrowFooter.cs
@@ -0,0 +1,96 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements. See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance with
+// the License.  You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+
+namespace Apache.Arrow.Ipc
+{
+    internal class ArrowFooter
+    {
+        public Schema Schema { get; }
+        private readonly List<Block> _dictionaries;
+        private readonly List<Block> _recordBatches;
+
+        public IEnumerable<Block> Dictionaries => _dictionaries;
+        public IEnumerable<Block> RecordBatches => _recordBatches;
+
+        public Block GetRecordBatchBlock(int i) => _recordBatches[i];
+
+        public Block GetDictionaryBlock(int i) => _dictionaries[i];
+
+        public int RecordBatchCount => _recordBatches.Count;
+        public int DictionaryCount => _dictionaries.Count;
+
+        public ArrowFooter(Schema schema, IEnumerable<Block> dictionaries, IEnumerable<Block> recordBatches)
+        {
+            Schema = schema;
+
+            _dictionaries = dictionaries.ToList();
+            _recordBatches = recordBatches.ToList();
+
+#if DEBUG
+            for (int i = 0; i < _dictionaries.Count; i++)
+            {
+                Block block = _dictionaries[i];
+                Debug.Assert(BitUtility.IsMultipleOf8(block.Offset));
+                Debug.Assert(BitUtility.IsMultipleOf8(block.MetadataLength));
+                Debug.Assert(BitUtility.IsMultipleOf8(block.BodyLength));
+            }
+
+            for (int i = 0; i < _recordBatches.Count; i++)
+            {
+                Block block = _recordBatches[i];
+                Debug.Assert(BitUtility.IsMultipleOf8(block.Offset));
+                Debug.Assert(BitUtility.IsMultipleOf8(block.MetadataLength));
+                Debug.Assert(BitUtility.IsMultipleOf8(block.BodyLength));
+            }
+#endif
+        }
+
+        public ArrowFooter(Flatbuf.Footer footer, ref DictionaryMemo dictionaryMemo)
+            : this(Ipc.MessageSerializer.GetSchema(footer.Schema.GetValueOrDefault(), ref dictionaryMemo), GetDictionaries(footer),
+                GetRecordBatches(footer))
+        { }
+
+        private static IEnumerable<Block> GetDictionaries(Flatbuf.Footer footer)
+        {
+            for (int i = 0; i < footer.DictionariesLength; i++)
+            {
+                Flatbuf.Block? block = footer.Dictionaries(i);
+
+                if (block.HasValue)
+                {
+                    yield return new Block(block.Value);
+                }
+            }
+        }
+
+        private static IEnumerable<Block> GetRecordBatches(Flatbuf.Footer footer)
+        {
+            for (int i = 0; i < footer.RecordBatchesLength; i++)
+            {
+                Flatbuf.Block? block = footer.RecordBatches(i);
+
+                if (block.HasValue)
+                {
+                    yield return new Block(block.Value);
+                }
+            }
+        }
+
+    }
+}