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ICSharpCode.TextEditor/Project/Src/Util/LookupTable.cs

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+// <file>
+//     <copyright see="prj:///doc/copyright.txt"/>
+//     <license see="prj:///doc/license.txt"/>
+//     <owner name="Mike Krüger" email="mike@icsharpcode.net"/>
+//     <version>$Revision$</version>
+// </file>
+
+using System;
+using ICSharpCode.TextEditor.Document;
+
+namespace ICSharpCode.TextEditor.Util
+{
+	/// <summary>
+	/// This class implements a keyword map. It implements a digital search trees (tries) to find
+	/// a word.
+	/// </summary>
+	public class LookupTable
+	{
+		Node root = new Node(null, null);
+		bool casesensitive;
+		int  length;
+		
+		/// <value>
+		/// The number of elements in the table
+		/// </value>
+		public int Count {
+			get {
+				return length;
+			}
+		}
+		
+		/// <summary>
+		/// Get the object, which was inserted under the keyword (line, at offset, with length length),
+		/// returns null, if no such keyword was inserted.
+		/// </summary>
+		public object this[IDocument document, LineSegment line, int offset, int length] {
+			get {
+				if(length == 0) {
+					return null;
+				}
+				Node next = root;
+				
+				int wordOffset = line.Offset + offset;
+				if (casesensitive) {
+					for (int i = 0; i < length; ++i) {
+						int index = ((int)document.GetCharAt(wordOffset + i)) % 256;
+						next = next[index];
+						
+						if (next == null) {
+							return null;
+						}
+						
+						if (next.color != null && TextUtility.RegionMatches(document, wordOffset, length, next.word)) {
+							return next.color;
+						}
+					}
+				} else {
+					for (int i = 0; i < length; ++i) {
+						int index = ((int)char.ToUpper(document.GetCharAt(wordOffset + i))) % 256;
+						
+						next = next[index];
+						
+						if (next == null) {
+							return null;
+						}
+						
+						if (next.color != null && TextUtility.RegionMatches(document, casesensitive, wordOffset, length, next.word)) {
+							return next.color;
+						}
+					}
+				}
+				return null;
+			}
+		}
+		
+		/// <summary>
+		/// Inserts an object in the tree, under keyword
+		/// </summary>
+		public object this[string keyword] {
+			set {
+				Node node = root;
+				Node next = root;
+				if (!casesensitive) {
+					keyword = keyword.ToUpper();
+				}
+				++length;
+				
+				// insert word into the tree
+				for (int i = 0; i < keyword.Length; ++i) {
+					int index = ((int)keyword[i]) % 256; // index of curchar
+					bool d = keyword[i] == '\\';
+					
+					next = next[index];             // get node to this index
+					
+					if (next == null) { // no node created -> insert word here
+						node[index] = new Node(value, keyword);
+						break;
+					}
+					
+					if (next.word != null && next.word.Length != i) { // node there, take node content and insert them again
+						string tmpword  = next.word;                  // this word will be inserted 1 level deeper (better, don't need too much
+						object tmpcolor = next.color;                 // string comparisons for finding.)
+						next.color = next.word = null;
+						this[tmpword] = tmpcolor;
+					}
+					
+					if (i == keyword.Length - 1) { // end of keyword reached, insert node there, if a node was here it was
+						next.word = keyword;       // reinserted, if it has the same length (keyword EQUALS this word) it will be overwritten
+						next.color = value;
+						break;
+					}
+					
+					node = next;
+				}
+			}
+		}
+		
+		/// <summary>
+		/// Creates a new instance of <see cref="LookupTable"/>
+		/// </summary>
+		public LookupTable(bool casesensitive)
+		{
+			this.casesensitive = casesensitive;
+		}
+		
+		class Node
+		{
+			public Node(object color, string word)
+			{
+				this.word  = word;
+				this.color = color;
+			}
+			
+			public string word;
+			public object color;
+			
+			// Lazily initialize children array. Saves 200 KB of memory for the C# highlighting
+			// because we don't have to store the array for leaf nodes.
+			public Node this[int index] {
+				get { 
+					if (children != null)
+						return children[index];
+					else
+						return null;
+				}
+				set {
+					if (children == null)
+						children = new Node[256];
+					children[index] = value;
+				}
+			}
+			
+			private Node[] children;
+		}
+	}
+}