Add anchor/alias support in JsonEventEmitter

YamlDotNet.Test/Serialization/SerializationTests.cs

@@ -27,19 +27,17 @@
 using System.ComponentModel;
 using System.Drawing;
 using System.Dynamic;
+using System.Globalization;
 using System.IO;
 using System.Linq;
-using System.Globalization;
 using System.Reflection;
 using System.Text.RegularExpressions;
 using Xunit;
 using YamlDotNet.Core;
 using YamlDotNet.Core.Events;
-using YamlDotNet.RepresentationModel;
 using YamlDotNet.Serialization;
 using YamlDotNet.Serialization.NamingConventions;
 using YamlDotNet.Serialization.ObjectFactories;
-using YamlDotNet.Serialization.TypeInspectors;
 
 namespace YamlDotNet.Test.Serialization
 {
@@ -810,6 +808,25 @@ public void SerializationOfLongKeysWorksInJson()
             writer.ToString().Should().NotContain("?");
         }
 
+        [Fact]
+        public void SerializationOfAnchorWorksInJson()
+        {
+            var deserializer = new DeserializerBuilder().Build();
+            var yamlObject = deserializer.Deserialize(Yaml.ReaderForText(@"
+x: &anchor1
+  z:
+    v: 1
+y:
+  k: *anchor1"));
+
+            var serializer = new SerializerBuilder()
+                .JsonCompatible()
+                .Build();
+
+            serializer.Serialize(yamlObject).Trim().Should()
+                .BeEquivalentTo(@"{""x"": {""z"": {""v"": ""1""}}, ""y"": {""k"": {""z"": {""v"": ""1""}}}}");
+        }
+
         [Fact]
         // Todo: this is actually roundtrip
         public void DeserializationOfDefaultsWorkInJson()

YamlDotNet/Core/Emitter.cs

@@ -45,6 +45,7 @@ public class Emitter : IEmitter
 
         private readonly int maxSimpleKeyLength;
         private readonly bool isCanonical;
+        private readonly bool skipAnchorName;
         private readonly int bestIndent;
         private readonly int bestWidth;
         private EmitterState state;
@@ -140,6 +141,7 @@ public Emitter(TextWriter output, EmitterSettings settings)
             this.bestWidth = settings.BestWidth;
             this.isCanonical = settings.IsCanonical;
             this.maxSimpleKeyLength = settings.MaxSimpleKeyLength;
+            this.skipAnchorName = settings.SkipAnchorName;
 
             this.output = output;
             this.outputUsesUnicodeEncoding = IsUnicode(output.Encoding);
@@ -1375,7 +1377,7 @@ private void EmitMappingStart(ParsingEvent evt)
 
         private void ProcessAnchor()
         {
-            if (anchorData.anchor != null)
+            if (anchorData.anchor != null && !skipAnchorName)
             {
                 WriteIndicator(anchorData.isAlias ? "*" : "&", true, false, false);
                 WriteAnchor(anchorData.anchor);

YamlDotNet/Core/EmitterSettings.cs

@@ -1,4 +1,25 @@
-using System;
+//  This file is part of YamlDotNet - A .NET library for YAML.
+//  Copyright (c) Antoine Aubry and contributors
+
+//  Permission is hereby granted, free of charge, to any person obtaining a copy of
+//  this software and associated documentation files (the "Software"), to deal in
+//  the Software without restriction, including without limitation the rights to
+//  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+//  of the Software, and to permit persons to whom the Software is furnished to do
+//  so, subject to the following conditions:
+
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+
+using System;
 
 namespace YamlDotNet.Core
 {
@@ -19,6 +40,11 @@ public sealed class EmitterSettings
         /// </summary>
         public bool IsCanonical { get; } = false;
 
+        /// <summary>
+        /// If true, write output without anchor names.
+        /// </summary>
+        public bool SkipAnchorName { get; private set; }
+
         /// <summary>
         /// The maximum allowed length for simple keys.
         /// </summary>
@@ -33,7 +59,7 @@ public EmitterSettings()
         {
         }
 
-        public EmitterSettings(int bestIndent, int bestWidth, bool isCanonical, int maxSimpleKeyLength)
+        public EmitterSettings(int bestIndent, int bestWidth, bool isCanonical, int maxSimpleKeyLength, bool skipAnchorName = false)
         {
             if (bestIndent < 2 || bestIndent > 9)
             {
@@ -54,6 +80,7 @@ public EmitterSettings(int bestIndent, int bestWidth, bool isCanonical, int maxS
             BestWidth = bestWidth;
             IsCanonical = isCanonical;
             MaxSimpleKeyLength = maxSimpleKeyLength;
+            SkipAnchorName = skipAnchorName;
         }
 
         public EmitterSettings WithBestIndent(int bestIndent)
@@ -95,5 +122,11 @@ public EmitterSettings Canonical()
                 MaxSimpleKeyLength
             );
         }
+
+        public EmitterSettings WithoutAnchorName()
+        {
+            SkipAnchorName = true;
+            return this;
+        }
     }
 }

YamlDotNet/Serialization/EventEmitters/JsonEventEmitter.cs

@@ -20,7 +20,6 @@
 //  SOFTWARE.
 
 using System;
-using System.Globalization;
 using YamlDotNet.Core;
 using YamlDotNet.Core.Events;
 
@@ -35,7 +34,7 @@ public JsonEventEmitter(IEventEmitter nextEmitter)
 
         public override void Emit(AliasEventInfo eventInfo, IEmitter emitter)
         {
-            throw new NotSupportedException("Aliases are not supported in JSON");
+            eventInfo.NeedsExpansion = true;
         }
 
         public override void Emit(ScalarEventInfo eventInfo, IEmitter emitter)
@@ -124,4 +123,4 @@ public override void Emit(SequenceStartEventInfo eventInfo, IEmitter emitter)
             base.Emit(eventInfo, emitter);
         }
     }
-}
+}

YamlDotNet/Serialization/EventInfo.cs

@@ -44,6 +44,7 @@ public AliasEventInfo(IObjectDescriptor source, string alias)
         }
 
         public string Alias { get; }
+        public bool NeedsExpansion { get; set; }
     }
 
     public class ObjectEventInfo : EventInfo
@@ -109,4 +110,4 @@ public SequenceEndEventInfo(IObjectDescriptor source)
         {
         }
     }
-}
+}

YamlDotNet/Serialization/ObjectGraphVisitors/AnchorAssigningObjectGraphVisitor.cs

@@ -45,8 +45,9 @@ public override bool Enter(IObjectDescriptor value, IEmitter context)
                 var alias = aliasProvider.GetAlias(value.Value);
                 if (alias != null && !emittedAliases.Add(alias))
                 {
-                    eventEmitter.Emit(new AliasEventInfo(value, alias), context);
-                    return false;
+                    var aliasEventInfo = new AliasEventInfo(value, alias);
+                    eventEmitter.Emit(aliasEventInfo, context);
+                    return aliasEventInfo.NeedsExpansion;
                 }
             }
             return base.Enter(value, context);
@@ -74,4 +75,4 @@ public override void VisitScalar(IObjectDescriptor scalar, IEmitter context)
             eventEmitter.Emit(scalarInfo, context);
         }
     }
-}
+}

YamlDotNet/Serialization/SerializerBuilder.cs

@@ -286,7 +286,9 @@ public SerializerBuilder ConfigureDefaultValuesHandling(DefaultValuesHandling co
         /// </summary>
         public SerializerBuilder JsonCompatible()
         {
-            this.emitterSettings = this.emitterSettings.WithMaxSimpleKeyLength(int.MaxValue);
+            this.emitterSettings = this.emitterSettings
+                                       .WithMaxSimpleKeyLength(int.MaxValue)
+                                       .WithoutAnchorName();
 
             return this
                 .WithTypeConverter(new GuidConverter(true), w => w.InsteadOf<GuidConverter>())
@@ -554,7 +556,7 @@ public void SerializeValue(IEmitter emitter, object? value, Type? type)
                 var preProcessingPhaseObjectGraphVisitors = preProcessingPhaseObjectGraphVisitorFactories.BuildComponentList(typeConverters);
                 foreach (var visitor in preProcessingPhaseObjectGraphVisitors)
                 {
-                    traversalStrategy.Traverse(graph, visitor, null);
+                    traversalStrategy.Traverse(graph, visitor, null!);
                 }
 
                 void nestedObjectSerializer(object? v, Type? t) => SerializeValue(emitter, v, t);
@@ -568,4 +570,4 @@ public void SerializeValue(IEmitter emitter, object? value, Type? type)
             }
         }
     }
-}
+}