adamreeve commented on code in PR #275: URL: https://github.com/apache/arrow-dotnet/pull/275#discussion_r2876675022
########## src/Apache.Arrow.Variant/Json/VariantJsonWriter.cs: ########## @@ -0,0 +1,260 @@ +// 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; +#if NET8_0_OR_GREATER +using System.Buffers; +#else +using System.IO; +#endif +using System.Data.SqlTypes; +using System.Text; +using System.Text.Json; + +namespace Apache.Arrow.Variant.Json +{ + /// <summary> + /// Writes variant binary data directly to JSON without creating intermediate + /// <see cref="VariantValue"/> objects. + /// </summary> + public static class VariantJsonWriter + { + /// <summary> + /// Converts variant binary data to a JSON string. + /// </summary> + /// <param name="metadata">The variant metadata bytes.</param> + /// <param name="value">The variant value bytes.</param> + /// <param name="indented">Whether to produce indented (pretty-printed) JSON.</param> + /// <returns>The JSON string representation.</returns> + public static string ToJson(byte[] metadata, byte[] value, bool indented = false) + { + JsonWriterOptions writerOptions = new JsonWriterOptions { Indented = indented }; +#if NET8_0_OR_GREATER + ArrayBufferWriter<byte> buffer = new ArrayBufferWriter<byte>(); + using (Utf8JsonWriter writer = new Utf8JsonWriter(buffer, writerOptions)) + { + VariantReader reader = new VariantReader(metadata, value); + WriteReader(writer, reader); + } + return Encoding.UTF8.GetString(buffer.WrittenSpan); +#else + using (MemoryStream ms = new MemoryStream()) + { + using (Utf8JsonWriter writer = new Utf8JsonWriter(ms, writerOptions)) + { + VariantReader reader = new VariantReader(metadata, value); + WriteReader(writer, reader); + } + return Encoding.UTF8.GetString(ms.GetBuffer(), 0, (int)ms.Position); Review Comment: Should we use checked here and in `ToJson` to catch overflows? ########## src/Apache.Arrow.Variant/VariantReader.cs: ########## @@ -0,0 +1,686 @@ +// 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.Buffers.Binary; +using System.Collections.Generic; +using System.Data.SqlTypes; +using System.Runtime.CompilerServices; +using System.Text; + +namespace Apache.Arrow.Variant +{ + /// <summary> + /// Zero-copy reader for a single variant value. Provides type inspection + /// and typed accessors for primitives, short strings, objects, and arrays. + /// </summary> + public ref struct VariantReader + { + private readonly ReadOnlySpan<byte> _metadata; + private readonly ReadOnlySpan<byte> _value; + + /// <summary> + /// Creates a reader over a variant value. + /// </summary> + /// <param name="metadata">The variant metadata buffer (shared across all values in a column).</param> + /// <param name="value">The variant value buffer for this specific value.</param> + public VariantReader(ReadOnlySpan<byte> metadata, ReadOnlySpan<byte> value) + { + _metadata = metadata; + _value = value; + } + + /// <summary>Gets the full metadata span.</summary> + public ReadOnlySpan<byte> Metadata => _metadata; + + /// <summary>Gets the full value span.</summary> + public ReadOnlySpan<byte> Value => _value; + + // --------------------------------------------------------------- + // Type inspection + // --------------------------------------------------------------- + + /// <summary>Gets the header byte of this value.</summary> + public byte Header => _value[0]; + + /// <summary>Gets the basic type of this value.</summary> + public VariantBasicType BasicType => VariantEncodingHelper.GetBasicType(Header); + + /// <summary> + /// Gets the primitive type when <see cref="BasicType"/> is <see cref="VariantBasicType.Primitive"/>. + /// </summary> + public VariantPrimitiveType PrimitiveType => VariantEncodingHelper.GetPrimitiveType(Header); Review Comment: Should throw InvalidOperationException if BasicType isn't Primitive? -- This is an automated message from the Apache Git Service. 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