1 files changed, 120 insertions, 0 deletions
diff --git a/main/src/core/Mono.Texteditor/Mono.TextEditor.Utils/RopeTextReader.cs b/main/src/core/Mono.Texteditor/Mono.TextEditor.Utils/RopeTextReader.cs
new file mode 100644
index 0000000000..b6827683db
--- /dev/null
+++ b/main/src/core/Mono.Texteditor/Mono.TextEditor.Utils/RopeTextReader.cs
@@ -0,0 +1,120 @@
+// Copyright (c) 2014 AlphaSierraPapa for the SharpDevelop Team
+// 
+// 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;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+
+namespace Mono.TextEditor.Utils
+{
+	/// <summary>
+	/// TextReader implementation that reads text from a rope.
+	/// </summary>
+	public sealed class RopeTextReader : TextReader
+	{
+		Stack<RopeNode<char>> stack = new Stack<RopeNode<char>>();
+		RopeNode<char> currentNode;
+		int indexInsideNode;
+
+		/// <summary>
+		/// Creates a new RopeTextReader.
+		/// Internally, this method creates a Clone of the rope; so the text reader will always read through the old
+		/// version of the rope if it is modified. <seealso cref="Rope{T}.Clone()"/>
+		/// </summary>
+		public RopeTextReader(Rope<char> rope)
+		{
+			if (rope == null)
+				throw new ArgumentNullException("rope");
+
+			// We force the user to iterate through a clone of the rope to keep the API contract of RopeTextReader simple
+			// (what happens when a rope is modified while iterating through it?)
+			rope.root.Publish();
+
+			// special case for the empty rope:
+			// leave currentNode initialized to null (RopeTextReader doesn't support empty nodes)
+			if (rope.Length != 0) {
+				currentNode = rope.root;
+				GoToLeftMostLeaf();
+			}
+		}
+
+		void GoToLeftMostLeaf()
+		{
+			while (currentNode.contents == null) {
+				if (currentNode.height == 0) {
+					// this is a function node - move to its contained rope
+					currentNode = currentNode.GetContentNode();
+					continue;
+				}
+				Debug.Assert(currentNode.right != null);
+				stack.Push(currentNode.right);
+				currentNode = currentNode.left;
+			}
+			Debug.Assert(currentNode.height == 0);
+		}
+
+		/// <inheritdoc/>
+		public override int Peek()
+		{
+			if (currentNode == null)
+				return -1;
+			return currentNode.contents[indexInsideNode];
+		}
+
+		/// <inheritdoc/>
+		public override int Read()
+		{
+			if (currentNode == null)
+				return -1;
+			char result = currentNode.contents[indexInsideNode++];
+			if (indexInsideNode >= currentNode.length)
+				GoToNextNode();
+			return result;
+		}
+
+		void GoToNextNode()
+		{
+			if (stack.Count == 0) {
+				currentNode = null;
+			} else {
+				indexInsideNode = 0;
+				currentNode = stack.Pop();
+				GoToLeftMostLeaf();
+			}
+		}
+
+		/// <inheritdoc/>
+		public override int Read(char[] buffer, int index, int count)
+		{
+			if (currentNode == null)
+				return 0;
+			int amountInCurrentNode = currentNode.length - indexInsideNode;
+			if (count < amountInCurrentNode) {
+				Array.Copy(currentNode.contents, indexInsideNode, buffer, index, count);
+				indexInsideNode += count;
+				return count;
+			} else {
+				// read to end of current node
+				Array.Copy(currentNode.contents, indexInsideNode, buffer, index, amountInCurrentNode);
+				GoToNextNode();
+				return amountInCurrentNode;
+			}
+		}
+	}
+}