XML Parser: Fast attribute lookup using hashtable

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@4622 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/XmlParser/Collections.cs

@@ -71,6 +71,98 @@ namespace ICSharpCode.AvalonEdit.XmlParser
 		}
 	}
 	
+	/// <summary>
+	/// Specailized attribute collection with attribute name caching
+	/// </summary>
+	public class AttributeCollection: FilteredCollection<RawAttribute, ChildrenCollection<RawObject>>
+	{
+		/// <summary> Wrap the given collection.  Non-attributes are filtered </summary>
+		public AttributeCollection(ChildrenCollection<RawObject> source): base(source) {}
+		
+		/// <summary> Wrap the given collection.  Non-attributes are filtered.  Items not matching the condition are filtered. </summary>
+		public AttributeCollection(ChildrenCollection<RawObject> source, Predicate<object> condition): base(source, condition) {}
+		
+		Dictionary<string, List<RawAttribute>> hashtable = new Dictionary<string, List<RawAttribute>>();
+		
+		void AddToHashtable(RawAttribute attr)
+		{
+			string localName = attr.LocalName;
+			if (!hashtable.ContainsKey(localName)) {
+				hashtable[localName] = new List<RawAttribute>(1);
+			}
+			hashtable[localName].Add(attr);
+		}
+		
+		void RemoveFromHashtable(RawAttribute attr)
+		{
+			string localName = attr.LocalName;
+			hashtable[localName].Remove(attr);
+		}
+		
+		static List<RawAttribute> NoAttributes = new List<RawAttribute>();
+		
+		/// <summary>
+		/// Get all attributes with given local name.
+		/// Hash table is used for lookup so this is cheap.
+		/// </summary>
+		public IEnumerable<RawAttribute> GetByLocalName(string localName)
+		{
+			if (hashtable.ContainsKey(localName)) {
+				return hashtable[localName];
+			} else {
+				return NoAttributes;
+			}
+		}
+		
+		/// <inheritdoc/>
+		protected override void ClearItems()
+		{
+			foreach(RawAttribute item in this) {
+				RemoveFromHashtable(item);
+				item.Changing -= item_Changing;
+				item.Changed  -= item_Changed;
+			}
+			base.ClearItems();
+		}
+		
+		/// <inheritdoc/>
+		protected override void InsertItem(int index, RawAttribute item)
+		{
+			AddToHashtable(item);
+			item.Changing += item_Changing;
+			item.Changed  += item_Changed;
+			base.InsertItem(index, item);
+		}
+		
+		/// <inheritdoc/>
+		protected override void RemoveItem(int index)
+		{
+			RemoveFromHashtable(this[index]);
+			this[index].Changing -= item_Changing;
+			this[index].Changed  -= item_Changed;
+			base.RemoveItem(index);
+		}
+		
+		/// <inheritdoc/>
+		protected override void SetItem(int index, RawAttribute item)
+		{
+			throw new NotSupportedException();
+		}
+		
+		// Every item in the collectoin should be registered to these handlers
+		// so that we can handle renames
+		
+		void item_Changing(object sender, RawObjectEventArgs e)
+		{
+			RemoveFromHashtable((RawAttribute)e.Object);
+		}
+		
+		void item_Changed(object sender, RawObjectEventArgs e)
+		{
+			AddToHashtable((RawAttribute)e.Object);
+		}
+	}
+	
 	/// <summary>
 	/// Collection that presents only some items from the wrapped collection.
 	/// It implicitely filters object that are not of type T (or derived).

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/XmlParser/RawObjects.cs

@@ -672,13 +672,13 @@ namespace ICSharpCode.AvalonEdit.XmlParser
 		
 		#region Helpper methods
 		
-		ObservableCollection<RawAttribute> attributes;
+		AttributeCollection attributes;
 		
 		/// <summary> Gets attributes of the element </summary>
-		public ObservableCollection<RawAttribute> Attributes {
+		public AttributeCollection Attributes {
 			get {
 				if (attributes == null) {
-					attributes = new FilteredCollection<RawAttribute, ChildrenCollection<RawObject>>(this.StartTag.Children);
+					attributes = new AttributeCollection(this.StartTag.Children);
 				}
 				return attributes;
 			}
@@ -786,9 +786,9 @@ namespace ICSharpCode.AvalonEdit.XmlParser
 		public string GetAttributeValue(string @namespace, string localName)
 		{
 			@namespace = @namespace ?? string.Empty;
-			// TODO: More efficient
-			foreach(RawAttribute attr in this.Attributes) {
-				if (attr.LocalName == localName && attr.Namespace == @namespace) {
+			foreach(RawAttribute attr in this.Attributes.GetByLocalName(localName)) {
+				Assert(attr.LocalName == localName);
+				if (attr.Namespace == @namespace) {
 					return attr.Value;
 				}
 			}