Platob commented on code in PR #37885: URL: https://github.com/apache/arrow/pull/37885#discussion_r1338945811
########## csharp/src/Apache.Arrow/Arrays/MapArray.cs: ########## @@ -0,0 +1,174 @@ +// 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; +using System.Collections.Generic; +using Apache.Arrow.Memory; +using Apache.Arrow.Types; + +namespace Apache.Arrow +{ + public class MapArray : ListArray // MapArray = ListArray(StrucArray("key", "value")) + { + // Same as ListArray.Builder, but with KeyBuilder + public new class Builder : IArrowArrayBuilder<MapArray, Builder> + { + public IArrowArrayBuilder<IArrowArray, IArrowArrayBuilder<IArrowArray>> KeyBuilder { get; } + public IArrowArrayBuilder<IArrowArray, IArrowArrayBuilder<IArrowArray>> ValueBuilder { get; } + + public int Length => ValueOffsetsBufferBuilder.Length; + + private ArrowBuffer.Builder<int> ValueOffsetsBufferBuilder { get; } + + private ArrowBuffer.BitmapBuilder ValidityBufferBuilder { get; } + + public int NullCount { get; protected set; } + + public MapType DataType { get; } + + public Builder(MapType type) + { + KeyBuilder = ArrowArrayBuilderFactory.Build(type.KeyField.DataType); + ValueBuilder = ArrowArrayBuilderFactory.Build(type.ValueField.DataType); + ValueOffsetsBufferBuilder = new ArrowBuffer.Builder<int>(); + ValidityBufferBuilder = new ArrowBuffer.BitmapBuilder(); + DataType = type; + } + + /// <summary> + /// Start a new variable-length list slot + /// + /// This function should be called before beginning to append elements to the + /// value builder + /// </summary> + /// <returns></returns> + public Builder Append() + { + ValueOffsetsBufferBuilder.Append(KeyBuilder.Length); + ValidityBufferBuilder.Append(true); + + return this; + } + + public Builder AppendNull() + { + ValueOffsetsBufferBuilder.Append(KeyBuilder.Length); + ValidityBufferBuilder.Append(false); + NullCount++; + + return this; + } + + public MapArray Build(MemoryAllocator allocator = default) + { + ValueOffsetsBufferBuilder.Append(KeyBuilder.Length); + + ArrowBuffer validityBuffer = NullCount > 0 ? ValidityBufferBuilder.Build(allocator) : ArrowBuffer.Empty; + + StructArray structs = new StructArray( + DataType.KeyValueType, KeyBuilder.Length, + new IArrowArray[] { KeyBuilder.Build(allocator), ValueBuilder.Build(allocator) }, + ArrowBuffer.Empty, 0 + ); + + return new MapArray(DataType, Length - 1, ValueOffsetsBufferBuilder.Build(allocator), structs, validityBuffer, NullCount); + } + + public Builder Reserve(int capacity) + { + ValueOffsetsBufferBuilder.Reserve(capacity + 1); + ValidityBufferBuilder.Reserve(capacity + 1); + return this; + } + + public Builder Resize(int length) + { + ValueOffsetsBufferBuilder.Resize(length + 1); + ValidityBufferBuilder.Resize(length + 1); + return this; + } + + public Builder Clear() + { + ValueOffsetsBufferBuilder.Clear(); + KeyBuilder.Clear(); + ValueBuilder.Clear(); + ValidityBufferBuilder.Clear(); + return this; + } + + } + + public StructArray KeyValues => base.Values as StructArray; + public IArrowArray Keys => KeyValues.Fields[0]; + public new IArrowArray Values => KeyValues.Fields[1]; + + public MapArray(IArrowType dataType, int length, + ArrowBuffer valueOffsetsBuffer, IArrowArray structs, + ArrowBuffer nullBitmapBuffer, int nullCount = 0, int offset = 0) + : this( + new ArrayData( + dataType, length, nullCount, offset, new[] { nullBitmapBuffer, valueOffsetsBuffer }, + new[] { structs.Data } + ), structs) + { + } + + public MapArray(ArrayData data) + : this(data, ArrowArrayFactory.BuildArray(data.Children[0])) + { + } + + private MapArray(ArrayData data, IArrowArray structs) : base(data, structs, ArrowTypeId.Map) + { + } + + public IEnumerable<Tuple<K, V>> GetTuples<TKeyArray, K, TValueArray, V>(int index, Func<TKeyArray, int, K> getKey, Func<TValueArray, int, V> getValue) + where TKeyArray : Array where TValueArray : Array + { + ReadOnlySpan<int> offsets = ValueOffsets; + // Get key values + int start = offsets[index]; + int end = offsets[index + 1]; + StructArray array = KeyValues.Slice(start, end - start) as StructArray; + + TKeyArray keyArray = array.Fields[0] as TKeyArray; + TValueArray valueArray = array.Fields[1] as TValueArray; + + for (int i = start; i < end; i++) + { + yield return new Tuple<K, V>(getKey(keyArray, i), getValue(valueArray, i)); + } + } + + public IEnumerable<KeyValuePair<K,V>> GetKeyValuePairs<TKeyArray, K, TValueArray, V>(int index, Func<TKeyArray, int, K> getKey, Func<TValueArray, int, V> getValue) + where TKeyArray : Array where TValueArray : Array + { + ReadOnlySpan<int> offsets = ValueOffsets; + // Get key values + int start = offsets[index]; + int end = offsets[index + 1]; + StructArray array = KeyValues.Slice(start, end - start) as StructArray; + + TKeyArray keyArray = array.Fields[0] as TKeyArray; + TValueArray valueArray = array.Fields[1] as TValueArray; + + for (int i = start; i < end; i++) + { + yield return new KeyValuePair<K,V>(getKey(keyArray, i), getValue(valueArray, i)); + } + } Review Comment: Ideally I would have preferred use something like c++ scalars, but it would need to be an abstract method Array.GetScalar(index) usable by all array data types, where we wouldn't need these external methods -- This is an automated message from the Apache Git Service. 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