Implement merge keys.

YamlDotNet/Core/MergingParser.cs

@@ -0,0 +1,73 @@
+using System.Collections.Generic;
+using System.Linq;
+using YamlDotNet.Core.Events;
+
+namespace YamlDotNet.Core
+{
+	/// <summary>
+	/// Simple implementation of <see cref="IParser"/> that implements merging: http://yaml.org/type/merge.html
+	/// </summary>
+	public sealed class MergingParser : IParser
+	{
+		private readonly List<ParsingEvent> _allEvents = new List<ParsingEvent>();
+		private readonly IParser _innerParser;
+		private int _currentIndex = -1;
+
+		public MergingParser(IParser innerParser)
+		{
+			_innerParser = innerParser;
+		}
+
+		public ParsingEvent Current { get; private set; }
+
+		public bool MoveNext()
+		{
+			if (_currentIndex < 0)
+			{
+				while (_innerParser.MoveNext())
+				{
+					_allEvents.Add(_innerParser.Current);
+				}
+
+				for (int i = _allEvents.Count - 2; i >= 0; --i)
+				{
+					var merge = _allEvents[i] as Scalar;
+					if (merge != null && merge.Value == "<<")
+					{
+						var anchorAlias = _allEvents[i + 1] as AnchorAlias;
+						if (anchorAlias != null)
+						{
+							var mergedEvents = GetMappingEvents(anchorAlias.Value);
+							_allEvents.RemoveRange(i, 2);
+							_allEvents.InsertRange(i, mergedEvents);
+						}
+
+					}
+				}
+			}
+
+			var nextIndex = _currentIndex + 1;
+			if (nextIndex < _allEvents.Count)
+			{
+				Current = _allEvents[nextIndex];
+				_currentIndex = nextIndex;
+				return true;
+			}
+			return false;
+		}
+
+		private IEnumerable<ParsingEvent> GetMappingEvents(string mappingAlias)
+		{
+			var nesting = 0;
+			return _allEvents
+				.SkipWhile(e =>
+				{
+					var mappingStart = e as MappingStart;
+					return mappingStart == null || mappingStart.Anchor != mappingAlias;
+				})
+				.Skip(1)
+				.TakeWhile(e => (nesting += e.NestingIncrease) >= 0)
+				.ToList();
+		}
+	}
+}

YamlDotNet/Serialization/NodeDeserializers/GenericDictionaryNodeDeserializer.cs

@@ -76,20 +76,20 @@ bool INodeDeserializer.Deserialize(EventReader reader, Type expectedType, Func<E
 					if (valuePromise == null)
 					{
 						// Happy path: both key and value are known
-						result.Add((TKey)key, (TValue)value);
+						result[(TKey)key] = (TValue)value;
 					}
 					else
 					{
 						// Key is known, value is pending
-						valuePromise.ValueAvailable += v => result.Add((TKey)key, (TValue)v);
+						valuePromise.ValueAvailable += v => result[(TKey)key] = (TValue)v;
 					}
 				}
 				else
 				{
 					if (valuePromise == null)
 					{
 						// Key is pending, value is known
-						keyPromise.ValueAvailable += v => result.Add((TKey)v, (TValue)value);
+						keyPromise.ValueAvailable += v => result[(TKey)v] = (TValue)value;
 					}
 					else
 					{
@@ -100,7 +100,7 @@ bool INodeDeserializer.Deserialize(EventReader reader, Type expectedType, Func<E
 						{
 							if (hasFirstPart)
 							{
-								result.Add((TKey)v, (TValue)value);
+								result[(TKey)v] = (TValue)value;
 							}
 							else
 							{
@@ -113,7 +113,7 @@ bool INodeDeserializer.Deserialize(EventReader reader, Type expectedType, Func<E
 						{
 							if (hasFirstPart)
 							{
-								result.Add((TKey)key, (TValue)v);
+								result[(TKey)key] = (TValue)v;
 							}
 							else
 							{

YamlDotNet/YamlDotNet.csproj

@@ -103,6 +103,7 @@
     <Compile Include="Core\IScanner.cs" />
     <Compile Include="Core\LookAheadBuffer.cs" />
     <Compile Include="Core\Mark.cs" />
+    <Compile Include="Core\MergingParser.cs" />
     <Compile Include="Core\Parser.cs" />
     <Compile Include="Core\ParserState.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />