Add pattern matching support in ParameterDeclaration.

ICSharpCode.Decompiler/CSharp/Syntax/TypeMembers/ParameterDeclaration.cs

@@ -45,6 +45,52 @@ namespace ICSharpCode.Decompiler.CSharp.Syntax
 		public static readonly TokenRole ThisModifierRole = new TokenRole("this");
 		public static readonly TokenRole InModifierRole = new TokenRole("in");
 
+		#region PatternPlaceholder
+		public static implicit operator ParameterDeclaration(PatternMatching.Pattern pattern)
+		{
+			return pattern != null ? new PatternPlaceholder(pattern) : null;
+		}
+
+		sealed class PatternPlaceholder : ParameterDeclaration, PatternMatching.INode
+		{
+			readonly PatternMatching.Pattern child;
+
+			public PatternPlaceholder(PatternMatching.Pattern child)
+			{
+				this.child = child;
+			}
+
+			public override NodeType NodeType {
+				get { return NodeType.Pattern; }
+			}
+
+			public override void AcceptVisitor(IAstVisitor visitor)
+			{
+				visitor.VisitPatternPlaceholder(this, child);
+			}
+
+			public override T AcceptVisitor<T>(IAstVisitor<T> visitor)
+			{
+				return visitor.VisitPatternPlaceholder(this, child);
+			}
+
+			public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
+			{
+				return visitor.VisitPatternPlaceholder(this, child, data);
+			}
+
+			protected internal override bool DoMatch(AstNode other, PatternMatching.Match match)
+			{
+				return child.DoMatch(other, match);
+			}
+
+			bool PatternMatching.INode.DoMatchCollection(Role role, PatternMatching.INode pos, PatternMatching.Match match, PatternMatching.BacktrackingInfo backtrackingInfo)
+			{
+				return child.DoMatchCollection(role, pos, match, backtrackingInfo);
+			}
+		}
+		#endregion
+
 		public override NodeType NodeType {
 			get {
 				return NodeType.Unknown;