Squashed 'NRefactory/' changes from a20e80a..ec42611

ec42611 Escape contextual keywords within query expressions.
7ba4e0b Add parenthesis around query expressions within type tests "(from a in b select c) is D"
7312982 Bugfixes for InsertParenthesesVisitor and OutputVisitor.
afd9650 Add query expressions to AST and output visitor.
880d23b Bug fixes in OutputVisitor.
594a637 Enable automatic removal when replacing a node with its own descendant.

git-subtree-dir: NRefactory
git-subtree-split: ec42611f0e7be19c53a16b2902808bd4d894b1ea

ICSharpCode.NRefactory.Tests/CSharp/InsertParenthesesVisitorTests.cs

@@ -10,12 +10,20 @@ namespace ICSharpCode.NRefactory.CSharp
 	[TestFixture]
 	public class InsertParenthesesVisitorTests
 	{
+		CSharpFormattingPolicy policy;
+		
+		[SetUp]
+		public void SetUp()
+		{
+			policy = new CSharpFormattingPolicy();
+		}
+		
 		string InsertReadable(Expression expr)
 		{
 			expr = expr.Clone();
 			expr.AcceptVisitor(new InsertParenthesesVisitor { InsertParenthesesForReadability = true }, null);
 			StringWriter w = new StringWriter();
-			expr.AcceptVisitor(new OutputVisitor(w, new CSharpFormattingPolicy()), null);
+			expr.AcceptVisitor(new OutputVisitor(w, policy), null);
 			return w.ToString();
 		}
 		
@@ -24,7 +32,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			expr = expr.Clone();
 			expr.AcceptVisitor(new InsertParenthesesVisitor { InsertParenthesesForReadability = false }, null);
 			StringWriter w = new StringWriter();
-			expr.AcceptVisitor(new OutputVisitor(w, new CSharpFormattingPolicy()), null);
+			expr.AcceptVisitor(new OutputVisitor(w, policy), null);
 			return w.ToString();
 		}
 		
@@ -87,5 +95,141 @@ namespace ICSharpCode.NRefactory.CSharp
 			Assert.AreEqual("((string)a).Length", InsertRequired(expr));
 			Assert.AreEqual("((string)a).Length", InsertReadable(expr));
 		}
+		
+		[Test]
+		public void DoubleNegation()
+		{
+			Expression expr = new UnaryOperatorExpression(
+				UnaryOperatorType.Minus,
+				new UnaryOperatorExpression(UnaryOperatorType.Minus, new IdentifierExpression("a"))
+			);
+			
+			Assert.AreEqual("- -a", InsertRequired(expr));
+			Assert.AreEqual("-(-a)", InsertReadable(expr));
+		}
+		
+		[Test]
+		public void TypeTestInConditional()
+		{
+			Expression expr = new ConditionalExpression {
+				Condition = new IdentifierExpression("a").IsType(
+					new ComposedType {
+						BaseType = new PrimitiveType("int"),
+						HasNullableSpecifier = true
+					}
+				),
+				TrueExpression = new IdentifierExpression("b"),
+				FalseExpression = new IdentifierExpression("c")
+			};
+			
+			Assert.AreEqual("a is int? ? b : c", InsertRequired(expr));
+			Assert.AreEqual("(a is int?) ? b : c", InsertReadable(expr));
+			
+			policy.ConditionalOperatorBeforeConditionSpace = false;
+			policy.ConditionalOperatorAfterConditionSpace = false;
+			policy.ConditionalOperatorBeforeSeparatorSpace = false;
+			policy.ConditionalOperatorAfterSeparatorSpace = false;
+			
+			Assert.AreEqual("a is int? ?b:c", InsertRequired(expr));
+			Assert.AreEqual("(a is int?)?b:c", InsertReadable(expr));
+		}
+		
+		[Test]
+		public void MethodCallOnQueryExpression()
+		{
+			Expression expr = new QueryExpression {
+				Clauses = new QueryClause[] {
+					new QueryFromClause {
+						Identifier = "a",
+						Expression = new IdentifierExpression("b")
+					},
+					new QuerySelectClause {
+						Expression = new IdentifierExpression("a").Invoke("c")
+					}
+				}
+			}.Invoke("ToArray");
+			
+			Assert.AreEqual("(from a in b" + Environment.NewLine + "select a.c ()).ToArray ()", InsertRequired(expr));
+			Assert.AreEqual("(from a in b" + Environment.NewLine + "select a.c ()).ToArray ()", InsertReadable(expr));
+		}
+		
+		[Test]
+		public void SumOfQueries()
+		{
+			QueryExpression query = new QueryExpression {
+				Clauses = new QueryClause[] {
+					new QueryFromClause {
+						Identifier = "a",
+						Expression = new IdentifierExpression("b")
+					},
+					new QuerySelectClause {
+						Expression = new IdentifierExpression("a")
+					}
+				}
+			};
+			Expression expr = new BinaryOperatorExpression(
+				query,
+				BinaryOperatorType.Add,
+				query.Clone()
+			);
+			
+			Assert.AreEqual("(from a in b" + Environment.NewLine +
+			                "select a) + from a in b" + Environment.NewLine +
+			                "select a", InsertRequired(expr));
+			Assert.AreEqual("(from a in b" + Environment.NewLine +
+			                "select a) + (from a in b" + Environment.NewLine +
+			                "select a)", InsertReadable(expr));
+		}
+		
+		[Test]
+		public void QueryInTypeTest()
+		{
+			Expression expr = new QueryExpression {
+				Clauses = new QueryClause[] {
+					new QueryFromClause {
+						Identifier = "a",
+						Expression = new IdentifierExpression("b")
+					},
+					new QuerySelectClause {
+						Expression = new IdentifierExpression("a")
+					}
+				}
+			}.IsType(new PrimitiveType("int"));
+			
+			Assert.AreEqual("(from a in b" + Environment.NewLine +
+			                "select a) is int", InsertRequired(expr));
+			Assert.AreEqual("(from a in b" + Environment.NewLine +
+			                "select a) is int", InsertReadable(expr));
+		}
+		
+		[Test]
+		public void PrePost()
+		{
+			Expression expr = new UnaryOperatorExpression(
+				UnaryOperatorType.Increment,
+				new UnaryOperatorExpression(
+					UnaryOperatorType.PostIncrement,
+					new IdentifierExpression("a")
+				)
+			);
+			
+			Assert.AreEqual("++a++", InsertRequired(expr));
+			Assert.AreEqual("++(a++)", InsertReadable(expr));
+		}
+		
+		[Test]
+		public void PostPre()
+		{
+			Expression expr = new UnaryOperatorExpression(
+				UnaryOperatorType.PostIncrement,
+				new UnaryOperatorExpression(
+					UnaryOperatorType.Increment,
+					new IdentifierExpression("a")
+				)
+			);
+			
+			Assert.AreEqual("(++a)++", InsertRequired(expr));
+			Assert.AreEqual("(++a)++", InsertReadable(expr));
+		}
 	}
 }

ICSharpCode.NRefactory/CSharp/Ast/AstNode.cs

@@ -129,6 +129,26 @@ namespace ICSharpCode.NRefactory.CSharp
 			}
 		}
 		
+		/// <summary>
+		/// Gets the ancestors of this node (excluding this node itself)
+		/// </summary>
+		public IEnumerable<AstNode> Ancestors {
+			get {
+				for (AstNode cur = parent; cur != null; cur = cur.parent) {
+					yield return cur;
+				}
+			}
+		}
+		
+		/// <summary>
+		/// Gets all descendants of this node (excluding this node itself).
+		/// </summary>
+		public IEnumerable<AstNode> Descendants {
+			get {
+				return Utils.TreeTraversal.PreOrder(this.Children, n => n.Children);
+			}
+		}
+		
 		/// <summary>
 		/// Gets the first child with the specified role.
 		/// Returns the role's null object if the child is not found.
@@ -291,20 +311,27 @@ namespace ICSharpCode.NRefactory.CSharp
 				Remove();
 				return;
 			}
-			if (this.parent == null) {
+			if (newNode == this)
+				return; // nothing to do...
+			if (parent == null) {
 				throw new InvalidOperationException(this.IsNull ? "Cannot replace the null nodes" : "Cannot replace the root node");
 			}
-			if (newNode.parent != null) {
-				// TODO: what if newNode is used within *this* tree?
-				// e.g. "parenthesizedExpr.ReplaceWith(parenthesizedExpr.Expression);"
-				// We'll probably want to allow that.
-				throw new ArgumentException ("Node is already used in another tree.", "newNode");
-			}
 			// Because this method doesn't statically check the new node's type with the role,
 			// we perform a runtime test:
 			if (!role.IsValid(newNode)) {
 				throw new ArgumentException (string.Format("The new node '{0}' is not valid in the role {1}", newNode.GetType().Name, role.ToString()), "newNode");
 			}
+			if (newNode.parent != null) {
+				// newNode is used within this tree?
+				if (newNode.Ancestors.Contains(this)) {
+					// e.g. "parenthesizedExpr.ReplaceWith(parenthesizedExpr.Expression);"
+					// enable automatic removal
+					newNode.Remove();
+				} else {
+					throw new ArgumentException ("Node is already used in another tree.", "newNode");
+				}
+			}
+			
 			newNode.parent = parent;
 			newNode.role = role;
 			newNode.prevSibling = prevSibling;
@@ -335,6 +362,9 @@ namespace ICSharpCode.NRefactory.CSharp
 		{
 			if (replaceFunction == null)
 				throw new ArgumentNullException("replaceFunction");
+			if (parent == null) {
+				throw new InvalidOperationException(this.IsNull ? "Cannot replace the null nodes" : "Cannot replace the root node");
+			}
 			AstNode oldParent = parent;
 			AstNode oldSuccessor = nextSibling;
 			Role oldRole = role;
@@ -402,13 +432,15 @@ namespace ICSharpCode.NRefactory.CSharp
 			
 			public object Clone()
 			{
-				AnnotationList copy = new AnnotationList(this.Count);
-				for (int i = 0; i < this.Count; i++) {
-					object obj = this[i];
-					ICloneable c = obj as ICloneable;
-					copy.Add(c != null ? c.Clone() : obj);
+				lock (this) {
+					AnnotationList copy = new AnnotationList(this.Count);
+					for (int i = 0; i < this.Count; i++) {
+						object obj = this[i];
+						ICloneable c = obj as ICloneable;
+						copy.Add(c != null ? c.Clone() : obj);
+					}
+					return copy;
 				}
-				return copy;
 			}
 		}
 		

ICSharpCode.NRefactory/CSharp/Ast/DepthFirstAstVisitor.cs

@@ -455,47 +455,55 @@ namespace ICSharpCode.NRefactory.CSharp
 			return VisitChildren (uncheckedExpression, data);
 		}
 		
-		/*
-		public virtual S VisitQueryExpressionFromClause (QueryExpressionFromClause queryExpressionFromClause, T data)
+		public virtual S VisitQueryExpression(QueryExpression queryExpression, T data)
 		{
-			return VisitChildren (queryExpressionFromClause, data);
+			return VisitChildren (queryExpression, data);
 		}
 		
-		public virtual S VisitQueryExpressionWhereClause (QueryExpressionWhereClause queryExpressionWhereClause, T data)
+		public virtual S VisitQueryContinuationClause(QueryContinuationClause queryContinuationClause, T data)
 		{
-			return VisitChildren (queryExpressionWhereClause, data);
+			return VisitChildren (queryContinuationClause, data);
 		}
 		
-		public virtual S VisitQueryExpressionJoinClause (QueryExpressionJoinClause queryExpressionJoinClause, T data)
+		public virtual S VisitQueryFromClause(QueryFromClause queryFromClause, T data)
 		{
-			return VisitChildren (queryExpressionJoinClause, data);
+			return VisitChildren (queryFromClause, data);
 		}
 		
-		public virtual S VisitQueryExpressionGroupClause (QueryExpressionGroupClause queryExpressionGroupClause, T data)
+		public virtual S VisitQueryLetClause(QueryLetClause queryLetClause, T data)
 		{
-			return VisitChildren (queryExpressionGroupClause, data);
+			return VisitChildren (queryLetClause, data);
 		}
 		
-		public virtual S VisitQueryExpressionLetClause (QueryExpressionLetClause queryExpressionLetClause, T data)
+		public virtual S VisitQueryWhereClause(QueryWhereClause queryWhereClause, T data)
 		{
-			return VisitChildren (queryExpressionLetClause, data);
+			return VisitChildren (queryWhereClause, data);
 		}
 		
-		public virtual S VisitQueryExpressionOrderClause (QueryExpressionOrderClause queryExpressionOrderClause, T data)
+		public virtual S VisitQueryJoinClause(QueryJoinClause queryJoinClause, T data)
 		{
-			return VisitChildren (queryExpressionOrderClause, data);
+			return VisitChildren (queryJoinClause, data);
 		}
 		
-		public virtual S VisitQueryExpressionOrdering (QueryExpressionOrdering queryExpressionOrdering, T data)
+		public virtual S VisitQueryOrderClause(QueryOrderClause queryOrderClause, T data)
 		{
-			return VisitChildren (queryExpressionOrdering, data);
+			return VisitChildren (queryOrderClause, data);
 		}
 		
-		public virtual S VisitQueryExpressionSelectClause (QueryExpressionSelectClause queryExpressionSelectClause, T data)
+		public virtual S VisitQueryOrdering(QueryOrdering queryOrdering, T data)
 		{
-			return VisitChildren (queryExpressionSelectClause, data);
+			return VisitChildren (queryOrdering, data);
+		}
+		
+		public virtual S VisitQuerySelectClause(QuerySelectClause querySelectClause, T data)
+		{
+			return VisitChildren (querySelectClause, data);
+		}
+		
+		public virtual S VisitQueryGroupClause(QueryGroupClause queryGroupClause, T data)
+		{
+			return VisitChildren (queryGroupClause, data);
 		}
-		*/
 		
 		public virtual S VisitAsExpression (AsExpression asExpression, T data)
 		{

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

@@ -117,6 +117,11 @@ namespace ICSharpCode.NRefactory.CSharp
 		{
 			return new AsExpression { Type = type,  Expression = this };
 		}
+		
+		public IsExpression IsType(AstType type)
+		{
+			return new IsExpression { Type = type,  Expression = this };
+		}
 		#endregion
 	}
 }

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

@@ -1,322 +1,354 @@
-// 
-// QueryExpression.cs
-//  
-// Author:
-//       Mike Krüger <mkrueger@novell.com>
-// 
-// Copyright (c) 2009 Novell, Inc (http://www.novell.com)
-// 
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-// 
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
-// 
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
+// 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;
+using System.Collections.Generic;
+using System.Linq;
 namespace ICSharpCode.NRefactory.CSharp
 {
-	/* TODO: how do we represent clauses? is QueryExpressionFromClause an expression,
-	 * or do we introduce a parent QueryExpression?
-	public class QueryExpressionFromClause : AstNode
+	public class QueryExpression : Expression
 	{
-		public const int FromKeywordRole = 100;
-		public const int InKeywordRole = 101;
+		public static readonly Role<QueryClause> ClauseRole = new Role<QueryClause>("Clause");
 		
-		public AstType Type {
-			get { return GetChildByRole (Roles.Type); }
-			set { SetChildByRole (Roles.Type, value); }
-		}
+		#region Null
+		public new static readonly QueryExpression Null = new NullQueryExpression ();
 		
-		public string Identifier {
-			get {
-				return QueryIdentifier.Name;
+		sealed class NullQueryExpression : QueryExpression
+		{
+			public override bool IsNull {
+				get {
+					return true;
+				}
 			}
-		}
-		
-		public Identifier QueryIdentifier {
-			get {
-				return (Identifier)GetChildByRole (Roles.Identifier) ?? ICSharpCode.NRefactory.CSharp.Identifier.Null;
+			
+			public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
+			{
+				return default (S);
 			}
 		}
+		#endregion
 		
-		public AstNode Expression {
-			get { return GetChildByRole (Roles.Expression) ?? AstNode.Null; }
+		public IEnumerable<QueryClause> Clauses {
+			get { return GetChildrenByRole(ClauseRole); }
+			set { SetChildrenByRole(ClauseRole, value); }
 		}
 		
-		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
+		public override S AcceptVisitor<T, S>(AstVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitQueryExpressionFromClause (this, data);
+			return visitor.VisitQueryExpression (this, data);
 		}
 	}
 	
-	public class QueryExpressionJoinClause : QueryExpressionFromClause
+	public abstract class QueryClause : AstNode
 	{
-		public const int OnExpressionRole     = 100;
-		public const int EqualsExpressionRole = 101;
-		public const int IntoIdentifierRole   = 102;
-		
-		public const int JoinKeywordRole     = 110;
-		public new const int InKeywordRole       = 111;
-		public const int OnKeywordRole       = 112;
-		public const int EqualsKeywordRole   = 113;
-		public const int IntoKeywordRole     = 114;
-		
-		public CSharpTokenNode JoinKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (JoinKeywordRole); }
-		}
-		public CSharpTokenNode InKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (InKeywordRole); }
-		}
-		public CSharpTokenNode OnKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (OnKeywordRole); }
-		}
-		public CSharpTokenNode EqualsKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (EqualsKeywordRole); }
-		}
-		public CSharpTokenNode IntoKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (IntoKeywordRole); }
+		public override NodeType NodeType {
+			get { return NodeType.QueryClause; }
 		}
+	}
+	
+	/// <summary>
+	/// Represents a query continuation.
+	/// "(from .. select ..) into Identifier" or "(from .. group .. by ..) into Identifier"
+	/// Note that "join .. into .." is not a query continuation!
+	/// 
+	/// This is always the first(!!) clause in a query expression.
+	/// The tree for "from a in b select c into d select e" looks like this:
+	/// new QueryExpression {
+	/// 	new QueryContinuationClause {
+	/// 		PrecedingQuery = new QueryExpression {
+	/// 			new QueryFromClause(a in b),
+	/// 			new QuerySelectClause(c)
+	/// 		},
+	/// 		Identifier = d
+	/// 	},
+	/// 	new QuerySelectClause(e)
+	/// }
+	/// </summary>
+	public class QueryContinuationClause : QueryClause
+	{
+		public static readonly Role<QueryExpression> PrecedingQueryRole = new Role<QueryExpression>("PrecedingQuery", QueryExpression.Null);
+		public static readonly Role<CSharpTokenNode> IntoKeywordRole = Roles.Keyword;
 		
+		public QueryExpression PrecedingQuery {
+			get { return GetChildByRole(PrecedingQueryRole); }
+			set { SetChildByRole(PrecedingQueryRole, value); }
+		}
 		
-		public AstNode OnExpression {
+		public string Identifier {
 			get {
-				return GetChildByRole (OnExpressionRole);
+				return GetChildByRole (Roles.Identifier).Name;
+			}
+			set {
+				SetChildByRole(Roles.Identifier, new Identifier(value, AstLocation.Empty));
 			}
 		}
 		
-		public AstNode EqualsExpression {
-			get {
-				return GetChildByRole (EqualsExpressionRole);
-			}
+		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
+		{
+			return visitor.VisitQueryContinuationClause (this, data);
 		}
+	}
+	
+	public class QueryFromClause : QueryClause
+	{
+		public static readonly Role<CSharpTokenNode> FromKeywordRole = Roles.Keyword;
+		public static readonly Role<CSharpTokenNode> InKeywordRole = Roles.InKeyword;
 		
-		public string IntoIdentifier {
-			get {
-				return IntoIdentifierIdentifier.Name;
-			}
+		public AstType Type {
+			get { return GetChildByRole (Roles.Type); }
+			set { SetChildByRole (Roles.Type, value); }
 		}
 		
-		public Identifier IntoIdentifierIdentifier {
+		public string Identifier {
 			get {
-				return (Identifier)GetChildByRole (IntoIdentifierRole);
+				return GetChildByRole (Roles.Identifier).Name;
+			}
+			set {
+				SetChildByRole(Roles.Identifier, new Identifier(value, AstLocation.Empty));
 			}
 		}
 		
-		public AstNode InExpression {
-			get {
-				return GetChildByRole (Roles.Expression);
-			}
+		public Expression Expression {
+			get { return GetChildByRole (Roles.Expression); }
+			set { SetChildByRole (Roles.Expression, value); }
 		}
 		
 		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitQueryExpressionJoinClause (this, data);
+			return visitor.VisitQueryFromClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionGroupClause : AstNode
+	public class QueryLetClause : QueryClause
 	{
-		public override NodeType NodeType {
+		public CSharpTokenNode LetKeyword {
+			get { return GetChildByRole(Roles.Keyword); }
+		}
+		
+		public string Identifier {
 			get {
-				return NodeType.Unknown;
+				return GetChildByRole(Roles.Identifier).Name;
+			}
+			set {
+				SetChildByRole(Roles.Identifier, new Identifier(value, AstLocation.Empty));
 			}
 		}
 		
-		public const int ProjectionExpressionRole = 100;
-		public const int GroupByExpressionRole    = 101;
-		
-		public const int GroupKeywordRole    = 102;
-		public const int ByKeywordRole    = 103;
-		
-		public CSharpTokenNode GroupKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (GroupKeywordRole); }
+		public CSharpTokenNode AssignToken {
+			get { return GetChildByRole(Roles.Assign); }
 		}
 		
-		public CSharpTokenNode ByKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (ByKeywordRole); }
+		public Expression Expression {
+			get { return GetChildByRole(Roles.Expression); }
+			set { SetChildByRole(Roles.Expression, value); }
 		}
 		
-		public AstNode Projection {
-			get {
-				return GetChildByRole (ProjectionExpressionRole);
-			}
+		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
+		{
+			return visitor.VisitQueryLetClause (this, data);
+		}
+	}
+	
+	
+	public class QueryWhereClause : QueryClause
+	{
+		public CSharpTokenNode WhereKeyword {
+			get { return GetChildByRole (Roles.Keyword); }
 		}
 		
-		public AstNode GroupBy {
-			get {
-				return GetChildByRole (GroupByExpressionRole);
-			}
+		public Expression Condition {
+			get { return GetChildByRole (Roles.Condition); }
+			set { SetChildByRole (Roles.Condition, value); }
 		}
 		
 		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitQueryExpressionGroupClause (this, data);
+			return visitor.VisitQueryWhereClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionLetClause : AstNode 
+	/// <summary>
+	/// Represents a join or group join clause.
+	/// </summary>
+	public class QueryJoinClause : QueryClause
 	{
-		public override NodeType NodeType {
-			get {
-				return NodeType.Unknown;
-			}
+		public static readonly Role<CSharpTokenNode> JoinKeywordRole = Roles.Keyword;
+		public static readonly Role<AstType> TypeRole = Roles.Type;
+		public static readonly Role<Identifier> JoinIdentifierRole = Roles.Identifier;
+		public static readonly Role<CSharpTokenNode> InKeywordRole = Roles.InKeyword;
+		public static readonly Role<Expression> InExpressionRole = Roles.Expression;
+		public static readonly Role<CSharpTokenNode> OnKeywordRole = new Role<CSharpTokenNode>("OnKeyword", CSharpTokenNode.Null);
+		public static readonly Role<Expression> OnExpressionRole = new Role<Expression>("OnExpression", Expression.Null);
+		public static readonly Role<CSharpTokenNode> EqualsKeywordRole = new Role<CSharpTokenNode>("EqualsKeyword", CSharpTokenNode.Null);
+		public static readonly Role<Expression> EqualsExpressionRole = new Role<Expression>("EqualsExpression", Expression.Null);
+		public static readonly Role<CSharpTokenNode> IntoKeywordRole = new Role<CSharpTokenNode>("IntoKeyword", CSharpTokenNode.Null);
+		public static readonly Role<Identifier> IntoIdentifierRole = new Role<Identifier>("IntoIdentifier", Identifier.Null);
+		
+		public bool IsGroupJoin {
+			get { return !string.IsNullOrEmpty(this.IntoIdentifier); }
 		}
 		
-		public string Identifier {
-			get {
-				return QueryIdentifier.Name;
-			}
+		public CSharpTokenNode JoinKeyword {
+			get { return GetChildByRole (JoinKeywordRole); }
 		}
 		
-		public Identifier QueryIdentifier {
-			get {
-				return (Identifier)GetChildByRole (Roles.Identifier);
-			}
+		public AstType Type {
+			get { return GetChildByRole (TypeRole); }
+			set { SetChildByRole (TypeRole, value); }
 		}
 		
-		public AstNode Expression {
+		public string JoinIdentifier {
 			get {
-				return GetChildByRole (Roles.Expression);
+				return GetChildByRole(JoinIdentifierRole).Name;
+			}
+			set {
+				SetChildByRole(JoinIdentifierRole, new Identifier(value, AstLocation.Empty));
 			}
 		}
 		
-		public CSharpTokenNode LetKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
+		public CSharpTokenNode InKeyword {
+			get { return GetChildByRole (InKeywordRole); }
 		}
 		
-		public AstNode Assign {
-			get {
-				return GetChildByRole (Roles.Assign);
-			}
+		public Expression InExpression {
+			get { return GetChildByRole (InExpressionRole); }
+			set { SetChildByRole (InExpressionRole, value); }
 		}
 		
-		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
-		{
-			return visitor.VisitQueryExpressionLetClause (this, data);
+		public CSharpTokenNode OnKeyword {
+			get { return GetChildByRole (OnKeywordRole); }
 		}
-	}
-	
-	public class QueryExpressionOrderClause : AstNode
-	{
-		public const int OrderingRole = 100;
 		
-		public override NodeType NodeType {
-			get {
-				return NodeType.Unknown;
-			}
+		public Expression OnExpression {
+			get { return GetChildByRole (OnExpressionRole); }
+			set { SetChildByRole (OnExpressionRole, value); }
 		}
 		
-		public bool OrderAscending {
-			get;
-			set;
+		public CSharpTokenNode EqualsKeyword {
+			get { return GetChildByRole (EqualsKeywordRole); }
+		}
+		
+		public Expression EqualsExpression {
+			get { return GetChildByRole (EqualsExpressionRole); }
+			set { SetChildByRole (EqualsExpressionRole, value); }
+		}
+		
+		public CSharpTokenNode IntoKeyword {
+			get { return GetChildByRole (IntoKeywordRole); }
 		}
 		
-		public AstNode Expression {
+		public string IntoIdentifier {
 			get {
-				return GetChildByRole (Roles.Expression);
+				return GetChildByRole (IntoIdentifierRole).Name;
+			}
+			set {
+				SetChildByRole(IntoIdentifierRole, new Identifier(value, AstLocation.Empty));
 			}
 		}
 		
+		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
+		{
+			return visitor.VisitQueryJoinClause (this, data);
+		}
+	}
+	
+	public class QueryOrderClause : QueryClause
+	{
+		public static readonly Role<QueryOrdering> OrderingRole = new Role<QueryOrdering>("Ordering");
+		
 		public CSharpTokenNode Keyword {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
+			get { return GetChildByRole (Roles.Keyword); }
+		}
+		
+		public IEnumerable<QueryOrdering> Orderings {
+			get { return GetChildrenByRole (OrderingRole); }
+			set { SetChildrenByRole (OrderingRole, value); }
 		}
 		
 		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitQueryExpressionOrderClause (this, data);
+			return visitor.VisitQueryOrderClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionOrdering : AstNode
+	public class QueryOrdering : AstNode
 	{
 		public override NodeType NodeType {
-			get {
-				return NodeType.Unknown;
-			}
+			get { return NodeType.Unknown; }
+		}
+		
+		public Expression Expression {
+			get { return GetChildByRole (Roles.Expression); }
+			set { SetChildByRole (Roles.Expression, value); }
 		}
 		
-		public QueryExpressionOrderingDirection Direction {
+		public QueryOrderingDirection Direction {
 			get;
 			set;
 		}
 		
-		public AstNode Criteria {
-			get {
-				return GetChildByRole (Roles.Expression);
-			}
+		public CSharpTokenNode DirectionToken {
+			get { return GetChildByRole (Roles.Keyword); }
 		}
 		
 		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitQueryExpressionOrdering (this, data);
+			return visitor.VisitQueryOrdering (this, data);
 		}
 	}
 	
-	public enum QueryExpressionOrderingDirection
+	public enum QueryOrderingDirection
 	{
-		Unknown,
+		None,
 		Ascending,
 		Descending
 	}
 	
-	public class QueryExpressionSelectClause : AstNode 
+	public class QuerySelectClause : QueryClause
 	{
-		public override NodeType NodeType {
-			get {
-				return NodeType.Unknown;
-			}
-		}
-		
 		public CSharpTokenNode SelectKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
+			get { return GetChildByRole (Roles.Keyword); }
 		}
 		
-		public AstNode Projection {
-			get {
-				return GetChildByRole (Roles.Expression);
-			}
+		public Expression Expression {
+			get { return GetChildByRole (Roles.Expression); }
+			set { SetChildByRole (Roles.Expression, value); }
 		}
 		
 		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitQueryExpressionSelectClause (this, data);
+			return visitor.VisitQuerySelectClause (this, data);
 		}
 	}
 	
-	public class QueryExpressionWhereClause : AstNode 
+	public class QueryGroupClause : QueryClause
 	{
-		public override NodeType NodeType {
-			get {
-				return NodeType.Unknown;
-			}
+		public static readonly Role<CSharpTokenNode> GroupKeywordRole = Roles.Keyword;
+		public static readonly Role<Expression> ProjectionRole = new Role<Expression>("Projection", Expression.Null);
+		public static readonly Role<CSharpTokenNode> ByKeywordRole = new Role<CSharpTokenNode>("ByKeyword", CSharpTokenNode.Null);
+		public static readonly Role<Expression> KeyRole = new Role<Expression>("Key", Expression.Null);
+		
+		public CSharpTokenNode GroupKeyword {
+			get { return GetChildByRole (GroupKeywordRole); }
 		}
 		
-		public CSharpTokenNode WhereKeyword {
-			get { return (CSharpTokenNode)GetChildByRole (Roles.Keyword); }
+		public Expression Projection {
+			get { return GetChildByRole (ProjectionRole); }
+			set { SetChildByRole (ProjectionRole, value); }
 		}
 		
-		public AstNode Condition {
-			get {
-				return GetChildByRole (Roles.Condition);
-			}
+		public CSharpTokenNode ByKeyword {
+			get { return GetChildByRole (ByKeywordRole); }
+		}
+		
+		public Expression Key {
+			get { return GetChildByRole (KeyRole); }
+			set { SetChildByRole (KeyRole, value); }
 		}
 		
 		public override S AcceptVisitor<T, S> (AstVisitor<T, S> visitor, T data)
 		{
-			return visitor.VisitQueryExpressionWhereClause (this, data);
+			return visitor.VisitQueryGroupClause (this, data);
 		}
-		
 	}
-	*/
 }

ICSharpCode.NRefactory/CSharp/Ast/IAstVisitor.cs

@@ -42,6 +42,17 @@ namespace ICSharpCode.NRefactory.CSharp
 		S VisitUnaryOperatorExpression(UnaryOperatorExpression unaryOperatorExpression, T data);
 		S VisitUncheckedExpression(UncheckedExpression uncheckedExpression, T data);
 		
+		S VisitQueryExpression(QueryExpression queryExpression, T data);
+		S VisitQueryContinuationClause(QueryContinuationClause queryContinuationClause, T data);
+		S VisitQueryFromClause(QueryFromClause queryFromClause, T data);
+		S VisitQueryLetClause(QueryLetClause queryLetClause, T data);
+		S VisitQueryWhereClause(QueryWhereClause queryWhereClause, T data);
+		S VisitQueryJoinClause(QueryJoinClause queryJoinClause, T data);
+		S VisitQueryOrderClause(QueryOrderClause queryOrderClause, T data);
+		S VisitQueryOrdering(QueryOrdering queryOrdering, T data);
+		S VisitQuerySelectClause(QuerySelectClause querySelectClause, T data);
+		S VisitQueryGroupClause(QueryGroupClause queryGroupClause, T data);
+		
 		S VisitAttribute(Attribute attribute, T data);
 		S VisitAttributeSection(AttributeSection attributeSection, T data);
 		S VisitDelegateDeclaration(DelegateDeclaration delegateDeclaration, T data);

ICSharpCode.NRefactory/CSharp/Ast/NodeType.cs

@@ -42,7 +42,8 @@ namespace ICSharpCode.NRefactory.CSharp
 		Member,
 		Statement,
 		Expression,
-		Token
+		Token,
+		QueryClause
 	}
 
 }

ICSharpCode.NRefactory/CSharp/OutputVisitor/IOutputFormatter.cs

@@ -10,8 +10,21 @@ namespace ICSharpCode.NRefactory.CSharp
 	/// </summary>
 	public interface IOutputFormatter
 	{
-		void WriteIdentifier(string ident);
+		/// <summary>
+		/// Writes an identifier.
+		/// If the identifier conflicts with a keyword, the output visitor will
+		/// call <c>WriteToken("@")</c> before calling WriteIdentifier().
+		/// </summary>
+		void WriteIdentifier(string identifier);
+		
+		/// <summary>
+		/// Writes a keyword to the output.
+		/// </summary>
 		void WriteKeyword(string keyword);
+		
+		/// <summary>
+		/// Writes a token to the output.
+		/// </summary>
 		void WriteToken(string token);
 		void Space();
 		

ICSharpCode.NRefactory/CSharp/OutputVisitor/InsertParenthesesVisitor.cs

@@ -20,12 +20,13 @@ namespace ICSharpCode.NRefactory.CSharp
 		/// </summary>
 		public bool InsertParenthesesForReadability { get; set; }
 		
-		const int Primary = 15;
+		const int Primary = 16;
+		const int QueryOrLambda = 15;
 		const int Unary = 14;
 		const int RelationalAndTypeTesting = 10;
 		const int Equality = 9;
 		const int Conditional = 2;
-		const int AssignmentAndLambda = 1;
+		const int Assignment = 1;
 		
 		/// <summary>
 		/// Gets the row number in the C# 4.0 spec operator precedence table.
@@ -33,6 +34,11 @@ namespace ICSharpCode.NRefactory.CSharp
 		static int GetPrecedence(Expression expr)
 		{
 			// Note: the operator precedence table on MSDN is incorrect
+			if (expr is QueryExpression) {
+				// Not part of the table in the C# spec, but we need to ensure that queries within
+				// primary expressions get parenthesized.
+				return QueryOrLambda;
+			}
 			UnaryOperatorExpression uoe = expr as UnaryOperatorExpression;
 			if (uoe != null) {
 				if (uoe.Operator == UnaryOperatorType.PostDecrement || uoe.Operator == UnaryOperatorType.PostIncrement)
@@ -84,7 +90,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			if (expr is ConditionalExpression)
 				return Conditional;
 			if (expr is AssignmentExpression || expr is LambdaExpression)
-				return AssignmentAndLambda;
+				return Assignment;
 			// anything else: primary expression
 			return Primary;
 		}
@@ -132,24 +138,22 @@ namespace ICSharpCode.NRefactory.CSharp
 		// Unary expressions
 		public override object VisitUnaryOperatorExpression(UnaryOperatorExpression unaryOperatorExpression, object data)
 		{
-			ParenthesizeIfRequired(unaryOperatorExpression.Expression, Unary);
+			ParenthesizeIfRequired(unaryOperatorExpression.Expression, GetPrecedence(unaryOperatorExpression));
+			UnaryOperatorExpression child = unaryOperatorExpression.Expression as UnaryOperatorExpression;
+			if (child != null && InsertParenthesesForReadability)
+				Parenthesize(child);
 			return base.VisitUnaryOperatorExpression(unaryOperatorExpression, data);
 		}
 		
 		public override object VisitCastExpression(CastExpression castExpression, object data)
 		{
-			ParenthesizeIfRequired(castExpression.Expression, Unary);
+			ParenthesizeIfRequired(castExpression.Expression, InsertParenthesesForReadability ? Primary : Unary);
 			// There's a nasty issue in the C# grammar: cast expressions including certain operators are ambiguous in some cases
 			// "(int)-1" is fine, but "(A)-b" is not a cast.
 			UnaryOperatorExpression uoe = castExpression.Expression as UnaryOperatorExpression;
-			if (InsertParenthesesForReadability) {
-				if (uoe != null)
+			if (uoe != null && !(uoe.Operator == UnaryOperatorType.BitNot || uoe.Operator == UnaryOperatorType.Not)) {
+				if (TypeCanBeMisinterpretedAsExpression(castExpression.Type)) {
 					Parenthesize(castExpression.Expression);
-			} else {
-				if (uoe != null && !(uoe.Operator == UnaryOperatorType.BitNot || uoe.Operator == UnaryOperatorType.Not)) {
-					if (TypeCanBeMisinterpretedAsExpression(castExpression.Type)) {
-						Parenthesize(castExpression.Expression);
-					}
 				}
 			}
 			return base.VisitCastExpression(castExpression, data);
@@ -238,15 +242,34 @@ namespace ICSharpCode.NRefactory.CSharp
 		public override object VisitAssignmentExpression(AssignmentExpression assignmentExpression, object data)
 		{
 			// assignment is right-associative
-			ParenthesizeIfRequired(assignmentExpression.Left, AssignmentAndLambda + 1);
+			ParenthesizeIfRequired(assignmentExpression.Left, Assignment + 1);
 			if (InsertParenthesesForReadability) {
 				ParenthesizeIfRequired(assignmentExpression.Right, RelationalAndTypeTesting + 1);
 			} else {
-				ParenthesizeIfRequired(assignmentExpression.Right, AssignmentAndLambda);
+				ParenthesizeIfRequired(assignmentExpression.Right, Assignment);
 			}
 			return base.VisitAssignmentExpression(assignmentExpression, data);
 		}
 		
 		// don't need to handle lambdas, they have lowest precedence and unambiguous associativity
+		
+		public override object VisitQueryExpression(QueryExpression queryExpression, object data)
+		{
+			// Query expressions are strange beasts:
+			// "var a = -from b in c select d;" is valid, so queries bind stricter than unary expressions.
+			// However, the end of the query is greedy. So their start sort of has a high precedence,
+			// while their end has a very low precedence. We handle this by checking whether a query is used
+			// as left part of a binary operator, and parenthesize it if required.
+			if (queryExpression.Role == BinaryOperatorExpression.LeftRole)
+				Parenthesize(queryExpression);
+			if (queryExpression.Parent is IsExpression || queryExpression.Parent is AsExpression)
+				Parenthesize(queryExpression);
+			if (InsertParenthesesForReadability) {
+				// when readability is desired, always parenthesize query expressions within unary or binary operators
+				if (queryExpression.Parent is UnaryOperatorExpression || queryExpression.Parent is BinaryOperatorExpression)
+					Parenthesize(queryExpression);
+			}
+			return base.VisitQueryExpression(queryExpression, data);
+		}
 	}
 }

ICSharpCode.NRefactory/CSharp/OutputVisitor/OutputVisitor.cs

@@ -22,7 +22,22 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		AstNode currentContainerNode;
 		readonly Stack<AstNode> positionStack = new Stack<AstNode>();
-		char lastChar;
+		
+		/// <summary>
+		/// Used to insert the minimal amount of spaces so that the lexer recognizes the tokens that were written.
+		/// </summary>
+		LastWritten lastWritten;
+		
+		enum LastWritten
+		{
+			Whitespace,
+			Other,
+			KeywordOrIdentifier,
+			Plus,
+			Minus,
+			QuestionMark,
+			Division
+		}
 		
 		public OutputVisitor(TextWriter textWriter, CSharpFormattingPolicy formattingPolicy)
 		{
@@ -131,7 +146,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			WriteSpecialsUpToRole(AstNode.Roles.Comma, nextNode);
 			Space(policy.SpacesBeforeComma);
 			formatter.WriteToken(",");
-			lastChar = ',';
+			lastWritten = LastWritten.Other;
 			Space(policy.SpacesAfterComma);
 		}
 		
@@ -178,26 +193,50 @@ namespace ICSharpCode.NRefactory.CSharp
 		void WriteKeyword(string keyword, Role<CSharpTokenNode> tokenRole = null)
 		{
 			WriteSpecialsUpToRole(tokenRole ?? AstNode.Roles.Keyword);
-			if (lastChar == 'a')
-				Space();
+			if (lastWritten == LastWritten.KeywordOrIdentifier)
+				formatter.Space();
 			formatter.WriteKeyword(keyword);
-			lastChar = 'a';
+			lastWritten = LastWritten.KeywordOrIdentifier;
 		}
 		
 		void WriteIdentifier(string identifier, Role<Identifier> identifierRole = null)
 		{
 			WriteSpecialsUpToRole(identifierRole ?? AstNode.Roles.Identifier);
-			if (lastChar == 'a')
-				Space();
+			if (IsKeyword(identifier, currentContainerNode)) {
+				formatter.WriteToken("@");
+			} else if (lastWritten == LastWritten.KeywordOrIdentifier) {
+				formatter.Space();
+			}
 			formatter.WriteIdentifier(identifier);
-			lastChar = 'a';
+			lastWritten = LastWritten.KeywordOrIdentifier;
 		}
 		
 		void WriteToken(string token, Role<CSharpTokenNode> tokenRole)
 		{
 			WriteSpecialsUpToRole(tokenRole);
+			// Avoid that two +, - or ? tokens are combined into a ++, -- or ?? token.
+			// Note that we don't need to handle tokens like = because there's no valid
+			// C# program that contains the single token twice in a row.
+			// (for + and -, this can happen with unary operators;
+			// and for ?, this can happen in "a is int? ? b : c" or "a as int? ?? 0")
+			if (lastWritten == LastWritten.Plus && token[0] == '+'
+			    || lastWritten == LastWritten.Minus && token[0] == '-'
+			    || lastWritten == LastWritten.QuestionMark && token[0] == '?'
+			    || lastWritten == LastWritten.Division && token[0] == '*')
+			{
+				formatter.Space();
+			}
 			formatter.WriteToken(token);
-			lastChar = token[token.Length - 1];
+			if (token == "+")
+				lastWritten = LastWritten.Plus;
+			else if (token == "-")
+				lastWritten = LastWritten.Minus;
+			else if (token == "?")
+				lastWritten = LastWritten.QuestionMark;
+			else if (token == "/")
+				lastWritten = LastWritten.Division;
+			else
+				lastWritten = LastWritten.Other;
 		}
 		
 		void LPar()
@@ -228,28 +267,62 @@ namespace ICSharpCode.NRefactory.CSharp
 		{
 			if (addSpace) {
 				formatter.Space();
-				lastChar = ' ';
+				lastWritten = LastWritten.Whitespace;
 			}
 		}
 		
 		void NewLine()
 		{
 			formatter.NewLine();
-			lastChar = '\n';
+			lastWritten = LastWritten.Whitespace;
 		}
 		
 		void OpenBrace(BraceStyle style)
 		{
 			WriteSpecialsUpToRole(AstNode.Roles.LBrace);
 			formatter.OpenBrace(style);
-			lastChar = '{';
+			lastWritten = LastWritten.Other;
 		}
 		
 		void CloseBrace(BraceStyle style)
 		{
 			WriteSpecialsUpToRole(AstNode.Roles.RBrace);
 			formatter.CloseBrace(style);
-			lastChar = '}';
+			lastWritten = LastWritten.Other;
+		}
+		#endregion
+		
+		#region IsKeyword Test
+		static readonly HashSet<string> unconditionalKeywords = new HashSet<string> {
+			"abstract", "as", "base", "bool", "break", "byte", "case", "catch",
+			"char", "checked", "class", "const", "continue", "decimal", "default", "delegate",
+			"do", "double", "else", "enum", "event", "explicit", "extern", "false",
+			"finally", "fixed", "float", "for", "foreach", "goto", "if", "implicit",
+			"in", "int", "interface", "internal", "is", "lock", "long", "namespace",
+			"new", "null", "object", "operator", "out", "override", "params", "private",
+			"protected", "public", "readonly", "ref", "return", "sbyte", "sealed", "short",
+			"sizeof", "stackalloc", "static", "string", "struct", "switch", "this", "throw",
+			"true", "try", "typeof", "uint", "ulong", "unchecked", "unsafe", "ushort",
+			"using", "virtual", "void", "volatile", "while"
+		};
+		
+		static readonly HashSet<string> queryKeywords = new HashSet<string> {
+			"from", "where", "join", "on", "equals", "into", "let", "orderby",
+			"ascending", "descending", "select", "group", "by"
+		};
+		
+		/// <summary>
+		/// Determines whether the specified identifier is a keyword in the given context.
+		/// </summary>
+		public static bool IsKeyword(string identifier, AstNode context)
+		{
+			if (unconditionalKeywords.Contains(identifier))
+				return true;
+			if (context.Ancestors.Any(a => a is QueryExpression)) {
+				if (queryKeywords.Contains(identifier))
+					return true;
+			}
+			return false;
 		}
 		#endregion
 		
@@ -285,13 +358,15 @@ namespace ICSharpCode.NRefactory.CSharp
 			foreach (Identifier ident in identifiers) {
 				if (first) {
 					first = false;
+					if (lastWritten == LastWritten.KeywordOrIdentifier)
+						formatter.Space();
 				} else {
 					WriteSpecialsUpToRole(AstNode.Roles.Dot, ident);
 					
 				}
 				WriteSpecialsUpToNode(ident);
 				formatter.WriteIdentifier(ident.Name);
-				lastChar = 'a';
+				lastWritten = LastWritten.KeywordOrIdentifier;
 			}
 		}
 		
@@ -660,7 +735,7 @@ namespace ICSharpCode.NRefactory.CSharp
 		{
 			StartNode(primitiveExpression);
 			formatter.WriteToken(ToCSharpString(primitiveExpression));
-			lastChar = 'a';
+			lastWritten = LastWritten.Other;
 			return EndNode(primitiveExpression);
 		}
 		
@@ -821,8 +896,13 @@ namespace ICSharpCode.NRefactory.CSharp
 		public object VisitUnaryOperatorExpression(UnaryOperatorExpression unaryOperatorExpression, object data)
 		{
 			StartNode(unaryOperatorExpression);
-			WriteToken(UnaryOperatorExpression.GetOperatorSymbol(unaryOperatorExpression.Operator), UnaryOperatorExpression.OperatorRole);
+			UnaryOperatorType opType = unaryOperatorExpression.Operator;
+			string opSymbol = UnaryOperatorExpression.GetOperatorSymbol(opType);
+			if (!(opType == UnaryOperatorType.PostIncrement || opType == UnaryOperatorType.PostDecrement))
+				WriteToken(opSymbol, UnaryOperatorExpression.OperatorRole);
 			unaryOperatorExpression.Expression.AcceptVisitor(this, data);
+			if (opType == UnaryOperatorType.PostIncrement || opType == UnaryOperatorType.PostDecrement)
+				WriteToken(opSymbol, UnaryOperatorExpression.OperatorRole);
 			return EndNode(unaryOperatorExpression);
 		}
 		
@@ -839,6 +919,143 @@ namespace ICSharpCode.NRefactory.CSharp
 		}
 		#endregion
 		
+		#region Query Expressions
+		public object VisitQueryExpression(QueryExpression queryExpression, object data)
+		{
+			StartNode(queryExpression);
+			bool first = true;
+			foreach (var clause in queryExpression.Clauses) {
+				if (first) {
+					first = false;
+				} else {
+					NewLine();
+				}
+				clause.AcceptVisitor(this, data);
+			}
+			return EndNode(queryExpression);
+		}
+		
+		public object VisitQueryContinuationClause(QueryContinuationClause queryContinuationClause, object data)
+		{
+			StartNode(queryContinuationClause);
+			queryContinuationClause.PrecedingQuery.AcceptVisitor(this, data);
+			Space();
+			WriteKeyword("into", QueryContinuationClause.IntoKeywordRole);
+			Space();
+			WriteIdentifier(queryContinuationClause.Identifier);
+			return EndNode(queryContinuationClause);
+		}
+		
+		public object VisitQueryFromClause(QueryFromClause queryFromClause, object data)
+		{
+			StartNode(queryFromClause);
+			WriteKeyword("from", QueryFromClause.FromKeywordRole);
+			queryFromClause.Type.AcceptVisitor(this, data);
+			Space();
+			WriteIdentifier(queryFromClause.Identifier);
+			WriteKeyword("in", QueryFromClause.InKeywordRole);
+			queryFromClause.Expression.AcceptVisitor(this, data);
+			return EndNode(queryFromClause);
+		}
+		
+		public object VisitQueryLetClause(QueryLetClause queryLetClause, object data)
+		{
+			StartNode(queryLetClause);
+			WriteKeyword("let");
+			Space();
+			WriteIdentifier(queryLetClause.Identifier);
+			Space(policy.AroundAssignmentParentheses);
+			WriteToken("=", QueryLetClause.Roles.Assign);
+			Space(policy.AroundAssignmentParentheses);
+			queryLetClause.Expression.AcceptVisitor(this, data);
+			return EndNode(queryLetClause);
+		}
+		
+		public object VisitQueryWhereClause(QueryWhereClause queryWhereClause, object data)
+		{
+			StartNode(queryWhereClause);
+			WriteKeyword("where");
+			Space();
+			queryWhereClause.Condition.AcceptVisitor(this, data);
+			return EndNode(queryWhereClause);
+		}
+		
+		public object VisitQueryJoinClause(QueryJoinClause queryJoinClause, object data)
+		{
+			StartNode(queryJoinClause);
+			WriteKeyword("join", QueryJoinClause.JoinKeywordRole);
+			queryJoinClause.Type.AcceptVisitor(this, data);
+			Space();
+			WriteIdentifier(queryJoinClause.JoinIdentifier, QueryJoinClause.JoinIdentifierRole);
+			Space();
+			WriteKeyword("in", QueryJoinClause.InKeywordRole);
+			Space();
+			queryJoinClause.InExpression.AcceptVisitor(this, data);
+			Space();
+			WriteKeyword("on", QueryJoinClause.OnKeywordRole);
+			Space();
+			queryJoinClause.OnExpression.AcceptVisitor(this, data);
+			Space();
+			WriteKeyword("equals", QueryJoinClause.EqualsKeywordRole);
+			Space();
+			queryJoinClause.EqualsExpression.AcceptVisitor(this, data);
+			if (queryJoinClause.IsGroupJoin) {
+				Space();
+				WriteKeyword("into", QueryJoinClause.IntoKeywordRole);
+				WriteIdentifier(queryJoinClause.IntoIdentifier, QueryJoinClause.IntoIdentifierRole);
+			}
+			return EndNode(queryJoinClause);
+		}
+		
+		public object VisitQueryOrderClause(QueryOrderClause queryOrderClause, object data)
+		{
+			StartNode(queryOrderClause);
+			WriteKeyword("orderby");
+			Space();
+			WriteCommaSeparatedList(queryOrderClause.Orderings);
+			return EndNode(queryOrderClause);
+		}
+		
+		public object VisitQueryOrdering(QueryOrdering queryOrdering, object data)
+		{
+			StartNode(queryOrdering);
+			queryOrdering.Expression.AcceptVisitor(this, data);
+			switch (queryOrdering.Direction) {
+				case QueryOrderingDirection.Ascending:
+					Space();
+					WriteKeyword("ascending");
+					break;
+				case QueryOrderingDirection.Descending:
+					Space();
+					WriteKeyword("descending");
+					break;
+			}
+			return EndNode(queryOrdering);
+		}
+		
+		public object VisitQuerySelectClause(QuerySelectClause querySelectClause, object data)
+		{
+			StartNode(querySelectClause);
+			WriteKeyword("select");
+			Space();
+			querySelectClause.Expression.AcceptVisitor(this, data);
+			return EndNode(querySelectClause);
+		}
+		
+		public object VisitQueryGroupClause(QueryGroupClause queryGroupClause, object data)
+		{
+			StartNode(queryGroupClause);
+			WriteKeyword("group", QueryGroupClause.GroupKeywordRole);
+			Space();
+			queryGroupClause.Projection.AcceptVisitor(this, data);
+			Space();
+			WriteKeyword("by", QueryGroupClause.ByKeywordRole);
+			Space();
+			queryGroupClause.Key.AcceptVisitor(this, data);
+			return EndNode(queryGroupClause);
+		}
+		#endregion
+		
 		#region GeneralScope
 		public object VisitAttribute(Attribute attribute, object data)
 		{
@@ -1633,7 +1850,7 @@ namespace ICSharpCode.NRefactory.CSharp
 			foreach (var comma in arraySpecifier.GetChildrenByRole(ArraySpecifier.Roles.Comma)) {
 				WriteSpecialsUpToNode(comma);
 				formatter.WriteToken(",");
-				lastChar = ',';
+				lastWritten = LastWritten.Other;
 			}
 			WriteToken("]", ArraySpecifier.Roles.RBracket);
 			return EndNode(arraySpecifier);
@@ -1648,7 +1865,13 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public object VisitComment(Comment comment, object data)
 		{
+			if (lastWritten == LastWritten.Division) {
+				// When there's a comment starting after a division operator
+				// "1.0 / /*comment*/a", then we need to insert a space in front of the comment.
+				formatter.Space();
+			}
 			formatter.WriteComment(comment.CommentType, comment.Content);
+			lastWritten = LastWritten.Whitespace;
 			return null;
 		}
 		

ICSharpCode.NRefactory/CSharp/OutputVisitor/TextWriterOutputFormatter.cs

@@ -90,7 +90,22 @@ namespace ICSharpCode.NRefactory.CSharp
 		
 		public void WriteComment(CommentType commentType, string content)
 		{
-			throw new NotImplementedException();
+			WriteIndentation();
+			switch (commentType) {
+				case CommentType.SingleLine:
+					textWriter.Write("//");
+					textWriter.WriteLine(content);
+					break;
+				case CommentType.MultiLine:
+					textWriter.Write("/*");
+					textWriter.Write(content);
+					textWriter.Write("*/");
+					break;
+				case CommentType.Documentation:
+					textWriter.Write("///");
+					textWriter.WriteLine(content);
+					break;
+			}
 		}
 	}
 }