Add visitor support to pattern nodes (IPatternAstVisitor). Add pattern support to output visitor (makes debugging easier if you can print out patterns)

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/AstNodeCollection.cs

@@ -175,7 +175,7 @@ namespace ICSharpCode.NRefactory.CSharp
 						break;
 					
 					Pattern pattern = cur1 as Pattern;
-					if (pattern == null && cur1.NodeType == NodeType.Pattern)
+					if (pattern == null && cur1.NodeType == NodeType.Placeholder)
 						pattern = cur1.GetChildByRole(TypePlaceholder.ChildRole) as Pattern;
 					if (pattern != null) {
 						Debug.Assert(stack.Count == patternStack.Count);

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/Expressions/Expression.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 
 namespace ICSharpCode.NRefactory.CSharp
@@ -50,6 +51,14 @@ namespace ICSharpCode.NRefactory.CSharp
 			return (Expression)base.Clone();
 		}
 		
+		// Make debugging easier by giving Expressions a ToString() implementation
+		public override string ToString()
+		{
+			StringWriter w = new StringWriter();
+			AcceptVisitor(new OutputVisitor(w, new CSharpFormattingPolicy()), null);
+			return w.ToString();
+		}
+		
 		public Expression ReplaceWith(Func<Expression, Expression> replaceFunction)
 		{
 			if (replaceFunction == null)

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/NodeType.cs

@@ -44,7 +44,8 @@ namespace ICSharpCode.NRefactory.CSharp
 		Expression,
 		Token,
 		QueryClause,
-		Pattern
+		Pattern,
+		Placeholder
 	}
 
 }

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/AnyNode.cs

@@ -12,6 +12,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 	{
 		readonly string groupName;
 		
+		public string GroupName {
+			get { return groupName; }
+		}
+		
 		public AnyNode(string groupName = null)
 		{
 			this.groupName = groupName;
@@ -22,5 +26,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 			match.Add(this.groupName, other);
 			return other != null && !other.IsNull;
 		}
+		
+		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
+		{
+			return ((IPatternAstVisitor<T, S>)visitor).VisitAnyNode(this, data);
+		}
 	}
 }

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/Backreference.cs

@@ -13,6 +13,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 	{
 		readonly string referencedGroupName;
 		
+		public string ReferencedGroupName {
+			get { return referencedGroupName; }
+		}
+		
 		public Backreference(string referencedGroupName)
 		{
 			if (referencedGroupName == null)
@@ -24,6 +28,11 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		{
 			return match.Get(referencedGroupName).Last().Match(other) != null;
 		}
+		
+		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
+		{
+			return ((IPatternAstVisitor<T, S>)visitor).VisitBackreference(this, data);
+		}
 	}
 	
 	/// <summary>
@@ -33,6 +42,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 	{
 		readonly string referencedGroupName;
 		
+		public string ReferencedGroupName {
+			get { return referencedGroupName; }
+		}
+		
 		public IdentifierExpressionBackreference(string referencedGroupName)
 		{
 			if (referencedGroupName == null)
@@ -48,5 +61,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 			AstNode referenced = match.Get(referencedGroupName).Last();
 			return ident.Identifier == referenced.GetChildByRole(AstNode.Roles.Identifier).Name;
 		}
+		
+		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
+		{
+			return ((IPatternAstVisitor<T, S>)visitor).VisitIdentifierExpressionBackreference(this, data);
+		}
 	}
 }

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/Choice.cs

@@ -3,13 +3,14 @@
 
 using System;
 using System.Collections;
+using System.Collections.Generic;
 
 namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 {
 	/// <summary>
 	/// Matches one of several alternatives.
 	/// </summary>
-	public class Choice : Pattern, IEnumerable
+	public class Choice : Pattern, IEnumerable<AstNode>
 	{
 		public static readonly Role<AstNode> AlternativeRole = new Role<AstNode>("Alternative", AstNode.Null);
 		
@@ -35,9 +36,19 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 			return false;
 		}
 		
+		IEnumerator<AstNode> IEnumerable<AstNode>.GetEnumerator()
+		{
+			return GetChildrenByRole(AlternativeRole).GetEnumerator();
+		}
+		
 		IEnumerator IEnumerable.GetEnumerator()
 		{
 			return GetChildrenByRole(AlternativeRole).GetEnumerator();
 		}
+		
+		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
+		{
+			return ((IPatternAstVisitor<T, S>)visitor).VisitChoice(this, data);
+		}
 	}
 }

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/IPatternAstVisitor.cs

@@ -0,0 +1,22 @@
+// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
+// This code is distributed under MIT X11 license (for details please see \doc\license.txt)
+
+using System;
+
+namespace ICSharpCode.NRefactory.CSharp.PatternMatching
+{
+	/// <summary>
+	/// Extended AST visitor that works for patterns.
+	/// </summary>
+	public interface IPatternAstVisitor<in T, out S> : IAstVisitor<T, S>
+	{
+		S VisitPlaceholder(AstNode placeholder, AstNode child, T data);
+		
+		S VisitAnyNode(AnyNode anyNode, T data);
+		S VisitBackreference(Backreference backreference, T data);
+		S VisitChoice(Choice choice, T data);
+		S VisitNamedNode(NamedNode namedNode, T data);
+		S VisitRepeat(Repeat repeat, T data);
+		S VisitIdentifierExpressionBackreference(IdentifierExpressionBackreference identifierExpressionBackreference, T data);
+	}
+}

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/NamedNode.cs

@@ -14,6 +14,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		
 		readonly string groupName;
 		
+		public string GroupName {
+			get { return groupName; }
+		}
+		
 		public NamedNode(string groupName, AstNode childNode)
 		{
 			this.groupName = groupName;
@@ -25,5 +29,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 			match.Add(this.groupName, other);
 			return GetChildByRole(ElementRole).DoMatch(other, match);
 		}
+		
+		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
+		{
+			return ((IPatternAstVisitor<T, S>)visitor).VisitNamedNode(this, data);
+		}
 	}
 }

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/Pattern.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.IO;
 
 namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 {
@@ -33,11 +34,6 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 			return DoMatch(pos, match);
 		}
 		
-		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
-		{
-			return default(S);
-		}
-		
 		public AstType ToType()
 		{
 			return new TypePlaceholder(this);
@@ -62,5 +58,13 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		{
 			return new VariablePlaceholder(this);
 		}
+		
+		// Make debugging easier by giving Patterns a ToString() implementation
+		public override string ToString()
+		{
+			StringWriter w = new StringWriter();
+			AcceptVisitor(new OutputVisitor(w, new CSharpFormattingPolicy()), null);
+			return w.ToString();
+		}
 	}
 }

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/Placeholder.cs

@@ -15,12 +15,12 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		}
 		
 		public override NodeType NodeType {
-			get { return GetChildByRole(TypePlaceholder.ChildRole).NodeType; }
+			get { return NodeType.Placeholder; }
 		}
 		
 		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
 		{
-			return GetChildByRole(TypePlaceholder.ChildRole).AcceptVisitor(visitor, data);
+			return ((IPatternAstVisitor<T, S>)visitor).VisitPlaceholder(this, GetChildByRole(TypePlaceholder.ChildRole), data);
 		}
 		
 		protected internal override bool DoMatch(AstNode other, Match match)
@@ -37,12 +37,12 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		}
 		
 		public override NodeType NodeType {
-			get { return GetChildByRole(TypePlaceholder.ChildRole).NodeType; }
+			get { return NodeType.Placeholder; }
 		}
 		
 		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
 		{
-			return GetChildByRole(TypePlaceholder.ChildRole).AcceptVisitor(visitor, data);
+			return ((IPatternAstVisitor<T, S>)visitor).VisitPlaceholder(this, GetChildByRole(TypePlaceholder.ChildRole), data);
 		}
 		
 		protected internal override bool DoMatch(AstNode other, Match match)
@@ -59,12 +59,12 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		}
 		
 		public override NodeType NodeType {
-			get { return GetChildByRole(TypePlaceholder.ChildRole).NodeType; }
+			get { return NodeType.Placeholder; }
 		}
 		
 		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
 		{
-			return GetChildByRole(TypePlaceholder.ChildRole).AcceptVisitor(visitor, data);
+			return ((IPatternAstVisitor<T, S>)visitor).VisitPlaceholder(this, GetChildByRole(TypePlaceholder.ChildRole), data);
 		}
 		
 		protected internal override bool DoMatch(AstNode other, Match match)
@@ -81,12 +81,12 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		}
 		
 		public override NodeType NodeType {
-			get { return GetChildByRole(TypePlaceholder.ChildRole).NodeType; }
+			get { return NodeType.Placeholder; }
 		}
 		
 		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
 		{
-			return GetChildByRole(TypePlaceholder.ChildRole).AcceptVisitor(visitor, data);
+			return ((IPatternAstVisitor<T, S>)visitor).VisitPlaceholder(this, GetChildByRole(TypePlaceholder.ChildRole), data);
 		}
 		
 		protected internal override bool DoMatch(AstNode other, Match match)
@@ -103,12 +103,12 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 		}
 		
 		public override NodeType NodeType {
-			get { return GetChildByRole(TypePlaceholder.ChildRole).NodeType; }
+			get { return NodeType.Placeholder; }
 		}
 		
 		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
 		{
-			return GetChildByRole(TypePlaceholder.ChildRole).AcceptVisitor(visitor, data);
+			return ((IPatternAstVisitor<T, S>)visitor).VisitPlaceholder(this, GetChildByRole(TypePlaceholder.ChildRole), data);
 		}
 		
 		protected internal override bool DoMatch(AstNode other, Match match)

NRefactory/ICSharpCode.NRefactory/CSharp/Ast/PatternMatching/Repeat.cs

@@ -46,5 +46,10 @@ namespace ICSharpCode.NRefactory.CSharp.PatternMatching
 			else
 				return this.MaxCount >= 1 && GetChildByRole(ElementRole).DoMatch(other, match);
 		}
+		
+		public override S AcceptVisitor<T, S>(IAstVisitor<T, S> visitor, T data)
+		{
+			return ((IPatternAstVisitor<T, S>)visitor).VisitRepeat(this, data);
+		}
 	}
 }

NRefactory/ICSharpCode.NRefactory/CSharp/OutputVisitor/OutputVisitor.cs

@@ -8,6 +8,8 @@ using System.Globalization;
 using System.IO;
 using System.Linq;
 using System.Text;
+
+using ICSharpCode.NRefactory.CSharp.PatternMatching;
 using ICSharpCode.NRefactory.TypeSystem;
 
 namespace ICSharpCode.NRefactory.CSharp
@@ -15,7 +17,7 @@ namespace ICSharpCode.NRefactory.CSharp
 	/// <summary>
 	/// Outputs the AST.
 	/// </summary>
-	public class OutputVisitor : IAstVisitor<object, object>
+	public class OutputVisitor : IPatternAstVisitor<object, object>
 	{
 		readonly IOutputFormatter formatter;
 		readonly CSharpFormattingPolicy policy;
@@ -1989,5 +1991,91 @@ namespace ICSharpCode.NRefactory.CSharp
 			return EndNode(identifier);
 		}
 		#endregion
+		
+		#region Pattern Nodes
+		object IPatternAstVisitor<object, object>.VisitPlaceholder(AstNode placeholder, AstNode child, object data)
+		{
+			StartNode(placeholder);
+			child.AcceptVisitor(this, data);
+			return EndNode(placeholder);
+		}
+		
+		object IPatternAstVisitor<object, object>.VisitAnyNode(AnyNode anyNode, object data)
+		{
+			StartNode(anyNode);
+			if (!string.IsNullOrEmpty(anyNode.GroupName)) {
+				WriteIdentifier(anyNode.GroupName);
+				WriteToken(":", AstNode.Roles.Colon);
+			}
+			WriteKeyword("anyNode");
+			return EndNode(anyNode);
+		}
+		
+		object IPatternAstVisitor<object, object>.VisitBackreference(Backreference backreference, object data)
+		{
+			StartNode(backreference);
+			WriteKeyword("backreference");
+			LPar();
+			WriteIdentifier(backreference.ReferencedGroupName);
+			RPar();
+			return EndNode(backreference);
+		}
+		
+		object IPatternAstVisitor<object, object>.VisitIdentifierExpressionBackreference(IdentifierExpressionBackreference identifierExpressionBackreference, object data)
+		{
+			StartNode(identifierExpressionBackreference);
+			WriteKeyword("identifierBackreference");
+			LPar();
+			WriteIdentifier(identifierExpressionBackreference.ReferencedGroupName);
+			RPar();
+			return EndNode(identifierExpressionBackreference);
+		}
+		
+		object IPatternAstVisitor<object, object>.VisitChoice(Choice choice, object data)
+		{
+			StartNode(choice);
+			WriteKeyword("choice");
+			Space();
+			LPar();
+			NewLine();
+			formatter.Indent();
+			foreach (AstNode alternative in choice) {
+				alternative.AcceptVisitor(this, data);
+				if (alternative != choice.LastChild)
+					WriteToken(",", AstNode.Roles.Comma);
+				NewLine();
+			}
+			formatter.Unindent();
+			RPar();
+			return EndNode(choice);
+		}
+		
+		object IPatternAstVisitor<object, object>.VisitNamedNode(NamedNode namedNode, object data)
+		{
+			StartNode(namedNode);
+			if (!string.IsNullOrEmpty(namedNode.GroupName)) {
+				WriteIdentifier(namedNode.GroupName);
+				WriteToken(":", AstNode.Roles.Colon);
+			}
+			namedNode.GetChildByRole(NamedNode.ElementRole).AcceptVisitor(this, data);
+			return EndNode(namedNode);
+		}
+		
+		object IPatternAstVisitor<object, object>.VisitRepeat(Repeat repeat, object data)
+		{
+			StartNode(repeat);
+			WriteKeyword("repeat");
+			LPar();
+			if (repeat.MinCount != 0 || repeat.MaxCount != int.MaxValue) {
+				WriteIdentifier(repeat.MinCount.ToString());
+				WriteToken(",", AstNode.Roles.Comma);
+				WriteIdentifier(repeat.MaxCount.ToString());
+				WriteToken(",", AstNode.Roles.Comma);
+			}
+			repeat.GetChildByRole(Repeat.ElementRole).AcceptVisitor(this, data);
+			RPar();
+			return EndNode(repeat);
+		}
+		#endregion
 	}
 }

NRefactory/ICSharpCode.NRefactory/ICSharpCode.NRefactory.csproj

@@ -98,8 +98,9 @@
     <Compile Include="CSharp\Ast\PatternMatching\Choice.cs" />
     <Compile Include="CSharp\Ast\PatternMatching\AnyNode.cs" />
     <Compile Include="CSharp\Ast\PatternMatching\Backreference.cs" />
+    <Compile Include="CSharp\Ast\PatternMatching\IPatternAstVisitor.cs" />
     <Compile Include="CSharp\Ast\PatternMatching\Match.cs" />
-    <Compile Include="CSharp\Ast\PatternMatching\NamedGroup.cs" />
+    <Compile Include="CSharp\Ast\PatternMatching\NamedNode.cs" />
     <Compile Include="CSharp\Ast\PatternMatching\Repeat.cs" />
     <Compile Include="CSharp\Ast\PatternMatching\Pattern.cs" />
     <Compile Include="CSharp\Ast\PatternMatching\Placeholder.cs" />