Merge branch 'master' of https://twinetfs.visualstudio.com/Tango/_git/Tango

1 files changed, 83 insertions, 0 deletions

diff --git a/Software/Visual_Studio/Scripting/Tango.Scripting.Editors/Document/LineNode.cs b/Software/Visual_Studio/Scripting/Tango.Scripting.Editors/Document/LineNode.cs
new file mode 100644
index 000000000..317202721
--- /dev/null
+++ b/Software/Visual_Studio/Scripting/Tango.Scripting.Editors/Document/LineNode.cs
@@ -0,0 +1,83 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
+
+using System;
+
+namespace Tango.Scripting.Editors.Document
+{
+	using LineNode = DocumentLine;
+	
+	// A tree node in the document line tree.
+	// For the purpose of the invariants, "children", "descendents", "siblings" etc. include the DocumentLine object,
+	// it is treated as a third child node between left and right.
+	
+	// Originally, this was a separate class, with a reference to the documentLine. The documentLine had a reference
+	// back to the node. To save memory, the same object is used for both the documentLine and the line node.
+	// This saves 16 bytes per line (8 byte object overhead + two pointers).
+//	sealed class LineNode
+//	{
+//		internal readonly DocumentLine documentLine;
+	partial class DocumentLine
+	{
+		internal DocumentLine left, right, parent;
+		internal bool color;
+		// optimization note: I tried packing color and isDeleted into a single byte field, but that
+		// actually increased the memory requirements. The JIT packs two bools and a byte (delimiterSize)
+		// into a single DWORD, but two bytes get each their own DWORD. Three bytes end up in the same DWORD, so
+		// apparently the JIT only optimizes for memory when there are at least three small fields.
+		// Currently, DocumentLine takes 36 bytes on x86 (8 byte object overhead, 3 pointers, 3 ints, and another DWORD
+		// for the small fields).
+		// TODO: a possible optimization would be to combine 'totalLength' and the small fields into a single uint.
+		// delimiterSize takes only two bits, the two bools take another two bits; so there's still 
+		// 28 bits left for totalLength. 268435455 characters per line should be enough for everyone :)
+		
+		/// <summary>
+		/// Resets the line to enable its reuse after a document rebuild.
+		/// </summary>
+		internal void ResetLine()
+		{
+			totalLength = delimiterLength = 0;
+			isDeleted = color = false;
+			left = right = parent = null;
+		}
+		
+		internal LineNode InitLineNode()
+		{
+			this.nodeTotalCount = 1;
+			this.nodeTotalLength = this.TotalLength;
+			return this;
+		}
+		
+		internal LineNode LeftMost {
+			get {
+				LineNode node = this;
+				while (node.left != null)
+					node = node.left;
+				return node;
+			}
+		}
+		
+		internal LineNode RightMost {
+			get {
+				LineNode node = this;
+				while (node.right != null)
+					node = node.right;
+				return node;
+			}
+		}
+		
+		/// <summary>
+		/// The number of lines in this node and its child nodes.
+		/// Invariant:
+		///   nodeTotalCount = 1 + left.nodeTotalCount + right.nodeTotalCount
+		/// </summary>
+		internal int nodeTotalCount;
+		
+		/// <summary>
+		/// The total text length of this node and its child nodes.
+		/// Invariant:
+		///   nodeTotalLength = left.nodeTotalLength + documentLine.TotalLength + right.nodeTotalLength
+		/// </summary>
+		internal int nodeTotalLength;
+	}
+}