From 8a600041f814898fd22be0150aeb1be3ba896a2d Mon Sep 17 00:00:00 2001
From: Cyrus Najmabadi <cyrusn@microsoft.com>
Date: Thu, 10 Dec 2015 15:56:27 -0800
Subject: [PATCH] Add serialization support for BKTrees.

---
 .../Core/Portable/Utilities/BKTree.Edge.cs    | 11 +++++
 .../Core/Portable/Utilities/BKTree.Node.cs    | 12 ++++++
 .../Utilities/BKTree.Serialization.cs         | 43 +++++++++++++++++++
 .../Core/Portable/Utilities/BKTree.cs         |  4 ++
 .../Core/Portable/Workspaces.csproj           |  1 +
 5 files changed, 71 insertions(+)
 create mode 100644 src/Workspaces/Core/Portable/Utilities/BKTree.Serialization.cs

diff --git a/src/Workspaces/Core/Portable/Utilities/BKTree.Edge.cs b/src/Workspaces/Core/Portable/Utilities/BKTree.Edge.cs
index 2aa54da3247..53107cc8cf7 100644
--- a/src/Workspaces/Core/Portable/Utilities/BKTree.Edge.cs
+++ b/src/Workspaces/Core/Portable/Utilities/BKTree.Edge.cs
@@ -21,6 +21,17 @@ public Edge(int editDistance, int childNodeIndex)
                 EditDistance = editDistance;
                 ChildNodeIndex = childNodeIndex;
             }
+
+            internal void WriteTo(ObjectWriter writer)
+            {
+                writer.WriteInt32(EditDistance);
+                writer.WriteInt32(ChildNodeIndex);
+            }
+
+            internal static Edge ReadFrom(ObjectReader reader)
+            {
+                return new Edge(reader.ReadInt32(), reader.ReadInt32());
+            }
         }
     }
 }
\ No newline at end of file
diff --git a/src/Workspaces/Core/Portable/Utilities/BKTree.Node.cs b/src/Workspaces/Core/Portable/Utilities/BKTree.Node.cs
index e84e0e7d32b..c5447a097cd 100644
--- a/src/Workspaces/Core/Portable/Utilities/BKTree.Node.cs
+++ b/src/Workspaces/Core/Portable/Utilities/BKTree.Node.cs
@@ -27,6 +27,18 @@ public Node(char[] lowerCaseCharacters, int edgeCount, int firstEdgeIndex)
                 EdgeCount = edgeCount;
                 FirstEdgeIndex = firstEdgeIndex;
             }
+
+            internal void WriteTo(ObjectWriter writer)
+            {
+                writer.WriteValue(LowerCaseCharacters);
+                writer.WriteInt32(EdgeCount);
+                writer.WriteInt32(FirstEdgeIndex);
+            }
+
+            internal static Node ReadFrom(ObjectReader reader)
+            {
+                return new Node((char[])reader.ReadValue(), reader.ReadInt32(), reader.ReadInt32());
+            }
         }
     }
 }
diff --git a/src/Workspaces/Core/Portable/Utilities/BKTree.Serialization.cs b/src/Workspaces/Core/Portable/Utilities/BKTree.Serialization.cs
new file mode 100644
index 00000000000..c45f3f74c61
--- /dev/null
+++ b/src/Workspaces/Core/Portable/Utilities/BKTree.Serialization.cs
@@ -0,0 +1,43 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Roslyn.Utilities
+{
+    internal partial class BKTree
+    {
+        internal void WriteTo(ObjectWriter writer)
+        {
+            writer.WriteInt32(this._nodes.Length);
+            foreach (var node in _nodes)
+            {
+                node.WriteTo(writer);
+            }
+
+            writer.WriteInt32(this._edges.Length);
+            foreach (var edge in _edges)
+            {
+                edge.WriteTo(writer);
+            }
+        }
+
+        internal static BKTree ReadFrom(ObjectReader reader)
+        {
+            var nodes = new Node[reader.ReadInt32()];
+            for (var i = 0; i < nodes.Length; i++)
+            {
+                nodes[i] = Node.ReadFrom(reader);
+            }
+
+            var edges = new Edge[reader.ReadInt32()];
+            for (var i = 0; i < edges.Length; i++)
+            {
+                edges[i] = Edge.ReadFrom(reader);
+            }
+
+            return new BKTree(nodes, edges);
+        }
+    }
+}
diff --git a/src/Workspaces/Core/Portable/Utilities/BKTree.cs b/src/Workspaces/Core/Portable/Utilities/BKTree.cs
index 84a717ef7ca..e36fe14510e 100644
--- a/src/Workspaces/Core/Portable/Utilities/BKTree.cs
+++ b/src/Workspaces/Core/Portable/Utilities/BKTree.cs
@@ -12,6 +12,10 @@ namespace Roslyn.Utilities
 {
     internal partial class BKTree
     {
+        public static readonly BKTree Empty = new BKTree(
+            SpecializedCollections.EmptyArray<Node>(),
+            SpecializedCollections.EmptyArray<Edge>());
+
         // We have two completely flat arrays of structs (except for the char[] values the nodes
         // point to).  These arrays fully represent the BK tree.  The structure is as follows:
         //
diff --git a/src/Workspaces/Core/Portable/Workspaces.csproj b/src/Workspaces/Core/Portable/Workspaces.csproj
index 64b24100700..9a349f16c20 100644
--- a/src/Workspaces/Core/Portable/Workspaces.csproj
+++ b/src/Workspaces/Core/Portable/Workspaces.csproj
@@ -418,6 +418,7 @@
     <Compile Include="Simplification\SimplifyTypeNameCodeAction.cs" />
     <Compile Include="Utilities\BKTree.Edge.cs" />
     <Compile Include="Utilities\BKTree.Node.cs" />
+    <Compile Include="Utilities\BKTree.Serialization.cs" />
     <Compile Include="Utilities\ForegroundThreadDataKind.cs" />
     <Compile Include="Utilities\IReadOnlyDictionaryExtensions.cs" />
     <Compile Include="Utilities\ValuesSources\CachedWeakValueSource.cs" />
-- 
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