// Copyright (c) AlphaSierraPapa for the SharpDevelop Team
// 
// 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.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using ICSharpCode.NRefactory.PatternMatching;
using ICSharpCode.NRefactory.TypeSystem;

namespace ICSharpCode.NRefactory.CSharp
{
	/// <summary>
	/// Outputs the AST.
	/// </summary>
	public class CSharpOutputVisitor : IAstVisitor
	{
		readonly IOutputFormatter formatter;
		readonly CSharpFormattingOptions policy;
		readonly Stack<AstNode> containerStack = new Stack<AstNode> ();
		readonly Stack<AstNode> positionStack = new Stack<AstNode> ();
		
		/// <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,
			Ampersand,
			QuestionMark,
			Division
		}
		
		public CSharpOutputVisitor (TextWriter textWriter, CSharpFormattingOptions formattingPolicy)
		{
			if (textWriter == null)
				throw new ArgumentNullException ("textWriter");
			if (formattingPolicy == null)
				throw new ArgumentNullException ("formattingPolicy");
			this.formatter = new TextWriterOutputFormatter (textWriter);
			this.policy = formattingPolicy;
		}
		
		public CSharpOutputVisitor (IOutputFormatter formatter, CSharpFormattingOptions formattingPolicy)
		{
			if (formatter == null)
				throw new ArgumentNullException ("formatter");
			if (formattingPolicy == null)
				throw new ArgumentNullException ("formattingPolicy");
			this.formatter = formatter;
			this.policy = formattingPolicy;
		}
		
		#region StartNode/EndNode
		void StartNode (AstNode node)
		{
			// Ensure that nodes are visited in the proper nested order.
			// Jumps to different subtrees are allowed only for the child of a placeholder node.
			Debug.Assert (containerStack.Count == 0 || node.Parent == containerStack.Peek () || containerStack.Peek ().NodeType == NodeType.Pattern);
			if (positionStack.Count > 0)
				WriteSpecialsUpToNode (node);
			containerStack.Push (node);
			positionStack.Push (node.FirstChild);
			formatter.StartNode (node);
		}
		
		void EndNode (AstNode node)
		{
			Debug.Assert (node == containerStack.Peek ());
			AstNode pos = positionStack.Pop ();
			Debug.Assert (pos == null || pos.Parent == node);
			WriteSpecials (pos, null);
			containerStack.Pop ();
			formatter.EndNode (node);
		}
		#endregion
		
		#region WriteSpecials
		/// <summary>
		/// Writes all specials from start to end (exclusive). Does not touch the positionStack.
		/// </summary>
		void WriteSpecials (AstNode start, AstNode end)
		{
			for (AstNode pos = start; pos != end; pos = pos.NextSibling) {
				if (pos.Role == Roles.Comment || pos.Role == Roles.PreProcessorDirective) {
					pos.AcceptVisitor (this);
				}
			}
		}
		
		/// <summary>
		/// Writes all specials between the current position (in the positionStack) and the next
		/// node with the specified role. Advances the current position.
		/// </summary>
		void WriteSpecialsUpToRole (Role role)
		{
			WriteSpecialsUpToRole (role, null);
		}
		
		void WriteSpecialsUpToRole (Role role, AstNode nextNode)
		{
			if (positionStack.Count == 0)
				return;
			// Look for the role between the current position and the nextNode.
			for (AstNode pos = positionStack.Peek(); pos != null && pos != nextNode; pos = pos.NextSibling) {
				if (pos.Role == role) {
					WriteSpecials (positionStack.Pop (), pos);
					// Push the next sibling because the node matching the role is not a special,
					// and should be considered to be already handled.
					positionStack.Push (pos.NextSibling);
					// This is necessary for OptionalComma() to work correctly.
					break;
				}
			}
		}
		
		/// <summary>
		/// Writes all specials between the current position (in the positionStack) and the specified node.
		/// Advances the current position.
		/// </summary>
		void WriteSpecialsUpToNode (AstNode node)
		{
			if (positionStack.Count == 0)
				return;
			for (AstNode pos = positionStack.Peek(); pos != null; pos = pos.NextSibling) {
				if (pos == node) {
					WriteSpecials (positionStack.Pop (), pos);
					// Push the next sibling because the node itself is not a special,
					// and should be considered to be already handled.
					positionStack.Push (pos.NextSibling);
					// This is necessary for OptionalComma() to work correctly.
					break;
				}
			}
		}
		#endregion
		
		#region Comma
		/// <summary>
		/// Writes a comma.
		/// </summary>
		/// <param name="nextNode">The next node after the comma.</param>
		/// <param name="noSpaceAfterComma">When set prevents printing a space after comma.</param>
		void Comma (AstNode nextNode, bool noSpaceAfterComma = false)
		{
			WriteSpecialsUpToRole (Roles.Comma, nextNode);
			Space (policy.SpaceBeforeBracketComma); // TODO: Comma policy has changed.
			formatter.WriteToken (",");
			lastWritten = LastWritten.Other;
			Space (!noSpaceAfterComma && policy.SpaceAfterBracketComma); // TODO: Comma policy has changed.
		}
		
		/// <summary>
		/// Writes an optional comma, e.g. at the end of an enum declaration or in an array initializer
		/// </summary>
		void OptionalComma()
		{
			// Look if there's a comma after the current node, and insert it if it exists.
			AstNode pos = positionStack.Peek();
			while (pos != null && pos.NodeType == NodeType.Whitespace)
				pos = pos.NextSibling;
			if (pos != null && pos.Role == Roles.Comma)
				Comma(null, noSpaceAfterComma: true);
		}
		
		/// <summary>
		/// Writes an optional semicolon, e.g. at the end of a type or namespace declaration.
		/// </summary>
		void OptionalSemicolon()
		{
			// Look if there's a semicolon after the current node, and insert it if it exists.
			AstNode pos = positionStack.Peek();
			while (pos != null && pos.NodeType == NodeType.Whitespace)
				pos = pos.NextSibling;
			if (pos != null && pos.Role == Roles.Semicolon)
				Semicolon();
		}
		
		void WriteCommaSeparatedList (IEnumerable<AstNode> list)
		{
			bool isFirst = true;
			foreach (AstNode node in list) {
				if (isFirst) {
					isFirst = false;
				} else {
					Comma (node);
				}
				node.AcceptVisitor (this);
			}
		}
		
		void WriteCommaSeparatedListInParenthesis (IEnumerable<AstNode> list, bool spaceWithin)
		{
			LPar ();
			if (list.Any ()) {
				Space (spaceWithin);
				WriteCommaSeparatedList (list);
				Space (spaceWithin);
			}
			RPar ();
		}
		
		#if DOTNET35
		void WriteCommaSeparatedList(IEnumerable<VariableInitializer> list)
		{
			WriteCommaSeparatedList(list.SafeCast<VariableInitializer, AstNode>());
		}
		
		void WriteCommaSeparatedList(IEnumerable<AstType> list)
		{
			WriteCommaSeparatedList(list.SafeCast<AstType, AstNode>());
		}
		
		void WriteCommaSeparatedListInParenthesis(IEnumerable<Expression> list, bool spaceWithin)
		{
			WriteCommaSeparatedListInParenthesis(list.SafeCast<Expression, AstNode>(), spaceWithin);
		}
		
		void WriteCommaSeparatedListInParenthesis(IEnumerable<ParameterDeclaration> list, bool spaceWithin)
		{
			WriteCommaSeparatedListInParenthesis(list.SafeCast<ParameterDeclaration, AstNode>(), spaceWithin);
		}

		#endif

		void WriteCommaSeparatedListInBrackets (IEnumerable<ParameterDeclaration> list, bool spaceWithin)
		{
			WriteToken (Roles.LBracket);
			if (list.Any ()) {
				Space (spaceWithin);
				WriteCommaSeparatedList (list);
				Space (spaceWithin);
			}
			WriteToken (Roles.RBracket);
		}

		void WriteCommaSeparatedListInBrackets (IEnumerable<Expression> list)
		{
			WriteToken (Roles.LBracket);
			if (list.Any ()) {
				Space (policy.SpacesWithinBrackets);
				WriteCommaSeparatedList (list);
				Space (policy.SpacesWithinBrackets);
			}
			WriteToken (Roles.RBracket);
		}
		#endregion
		
		#region Write tokens
		/// <summary>
		/// Writes a keyword, and all specials up to
		/// </summary>
		void WriteKeyword (TokenRole tokenRole)
		{
			WriteKeyword (tokenRole.Token, tokenRole);
		}
		
		void WriteKeyword (string token, Role tokenRole = null)
		{
			if (tokenRole != null)
				WriteSpecialsUpToRole (tokenRole);
			if (lastWritten == LastWritten.KeywordOrIdentifier)
				formatter.Space ();
			formatter.WriteKeyword (token);
			lastWritten = LastWritten.KeywordOrIdentifier;
		}
		
/*		void WriteKeyword (string keyword, Role tokenRole)
		{
			WriteSpecialsUpToRole (tokenRole);
			if (lastWritten == LastWritten.KeywordOrIdentifier)
				formatter.Space ();
			formatter.WriteKeyword (keyword);
			lastWritten = LastWritten.KeywordOrIdentifier;
		}*/
		
		void WriteIdentifier (string identifier, Role<Identifier> identifierRole = null)
		{
			WriteSpecialsUpToRole (identifierRole ?? Roles.Identifier);
			if (IsKeyword (identifier, containerStack.Peek ())) {
				if (lastWritten == LastWritten.KeywordOrIdentifier)
					Space (); // this space is not strictly required, so we call Space()
				formatter.WriteToken ("@");
			} else if (lastWritten == LastWritten.KeywordOrIdentifier) {
				formatter.Space (); // this space is strictly required, so we directly call the formatter
			}
			formatter.WriteIdentifier (identifier);
			lastWritten = LastWritten.KeywordOrIdentifier;
		}
		
		void WriteToken (TokenRole tokenRole)
		{
			WriteToken (tokenRole.Token, tokenRole);
		}
			
		void WriteToken (string token, Role 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;
			// for ?, this can happen in "a is int? ? b : c" or "a as int? ?? 0";
			// and for /, this can happen with "1/ *ptr" or "1/ //comment".)
			if (lastWritten == LastWritten.Plus && token [0] == '+'
			    || lastWritten == LastWritten.Minus && token [0] == '-'
			    || lastWritten == LastWritten.Ampersand && token [0] == '&'
			    || lastWritten == LastWritten.QuestionMark && token [0] == '?'
			    || lastWritten == LastWritten.Division && token [0] == '*') {
				formatter.Space ();
			}
			formatter.WriteToken (token);
			if (token == "+")
				lastWritten = LastWritten.Plus;
			else if (token == "-")
				lastWritten = LastWritten.Minus;
			else if (token == "&")
				lastWritten = LastWritten.Ampersand;
			else if (token == "?")
				lastWritten = LastWritten.QuestionMark;
			else if (token == "/")
				lastWritten = LastWritten.Division;
			else
				lastWritten = LastWritten.Other;
		}
		
		void LPar ()
		{
			WriteToken (Roles.LPar);
		}
		
		void RPar ()
		{
			WriteToken (Roles.RPar);
		}
		
		/// <summary>
		/// Marks the end of a statement
		/// </summary>
		void Semicolon ()
		{
			Role role = containerStack.Peek ().Role; // get the role of the current node
			if (!(role == ForStatement.InitializerRole || role == ForStatement.IteratorRole || role == UsingStatement.ResourceAcquisitionRole)) {
				WriteToken (Roles.Semicolon);
				NewLine ();
			}
		}
		
		/// <summary>
		/// Writes a space depending on policy.
		/// </summary>
		void Space (bool addSpace = true)
		{
			if (addSpace) {
				formatter.Space ();
				lastWritten = LastWritten.Whitespace;
			}
		}
		
		void NewLine ()
		{
			formatter.NewLine ();
			lastWritten = LastWritten.Whitespace;
		}
		
		void OpenBrace (BraceStyle style)
		{
			WriteSpecialsUpToRole (Roles.LBrace);
			formatter.OpenBrace (style);
			lastWritten = LastWritten.Other;
		}
		
		void CloseBrace (BraceStyle style)
		{
			WriteSpecialsUpToRole (Roles.RBrace);
			formatter.CloseBrace (style);
			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;
			foreach (AstNode ancestor in context.Ancestors) {
				if (ancestor is QueryExpression && queryKeywords.Contains (identifier))
					return true;
				if (identifier == "await") {
					// with lambdas/anonymous methods,
					if (ancestor is LambdaExpression)
						return ((LambdaExpression)ancestor).IsAsync;
					if (ancestor is AnonymousMethodExpression)
						return ((AnonymousMethodExpression)ancestor).IsAsync;
					if (ancestor is EntityDeclaration)
						return (((EntityDeclaration)ancestor).Modifiers & Modifiers.Async) == Modifiers.Async;
				}
			}
			return false;
		}
		#endregion
		
		#region Write constructs
		void WriteTypeArguments (IEnumerable<AstType> typeArguments)
		{
			if (typeArguments.Any ()) {
				WriteToken (Roles.LChevron);
				WriteCommaSeparatedList (typeArguments);
				WriteToken (Roles.RChevron);
			}
		}
		
		public void WriteTypeParameters (IEnumerable<TypeParameterDeclaration> typeParameters)
		{
			if (typeParameters.Any ()) {
				WriteToken (Roles.LChevron);
				WriteCommaSeparatedList (typeParameters);
				WriteToken (Roles.RChevron);
			}
		}
		
		void WriteModifiers (IEnumerable<CSharpModifierToken> modifierTokens)
		{
			foreach (CSharpModifierToken modifier in modifierTokens) {
				modifier.AcceptVisitor (this);
			}
		}
		
		void WriteQualifiedIdentifier (IEnumerable<Identifier> identifiers)
		{
			bool first = true;
			foreach (Identifier ident in identifiers) {
				if (first) {
					first = false;
					if (lastWritten == LastWritten.KeywordOrIdentifier)
						formatter.Space ();
				} else {
					WriteSpecialsUpToRole (Roles.Dot, ident);
					formatter.WriteToken (".");
					lastWritten = LastWritten.Other;
				}
				WriteSpecialsUpToNode (ident);
				formatter.WriteIdentifier (ident.Name);
				lastWritten = LastWritten.KeywordOrIdentifier;
			}
		}
		
		void WriteEmbeddedStatement (Statement embeddedStatement)
		{
			if (embeddedStatement.IsNull)
				return;
			BlockStatement block = embeddedStatement as BlockStatement;
			if (block != null)
				VisitBlockStatement (block);
			else {
				NewLine ();
				formatter.Indent ();
				embeddedStatement.AcceptVisitor (this);
				formatter.Unindent ();
			}
		}
		
		void WriteMethodBody (BlockStatement body)
		{
			if (body.IsNull)
				Semicolon ();
			else
				VisitBlockStatement (body);
		}
		
		void WriteAttributes (IEnumerable<AttributeSection> attributes)
		{
			foreach (AttributeSection attr in attributes) {
				attr.AcceptVisitor (this);
			}
		}
		
		void WritePrivateImplementationType (AstType privateImplementationType)
		{
			if (!privateImplementationType.IsNull) {
				privateImplementationType.AcceptVisitor (this);
				WriteToken (Roles.Dot);
			}
		}

		#endregion
		
		#region Expressions
		public void VisitAnonymousMethodExpression (AnonymousMethodExpression anonymousMethodExpression)
		{
			StartNode (anonymousMethodExpression);
			if (anonymousMethodExpression.IsAsync) {
				WriteKeyword (AnonymousMethodExpression.AsyncModifierRole);
				Space ();
			}
			WriteKeyword (AnonymousMethodExpression.DelegateKeywordRole);
			if (anonymousMethodExpression.HasParameterList) {
				Space (policy.SpaceBeforeMethodDeclarationParentheses);
				WriteCommaSeparatedListInParenthesis (anonymousMethodExpression.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			}
			anonymousMethodExpression.Body.AcceptVisitor (this);
			EndNode (anonymousMethodExpression);
		}
		
		public void VisitUndocumentedExpression (UndocumentedExpression undocumentedExpression)
		{
			StartNode (undocumentedExpression);
			switch (undocumentedExpression.UndocumentedExpressionType) {
				case UndocumentedExpressionType.ArgList:
				case UndocumentedExpressionType.ArgListAccess:
					WriteKeyword (UndocumentedExpression.ArglistKeywordRole);
					break;
				case UndocumentedExpressionType.MakeRef:
					WriteKeyword (UndocumentedExpression.MakerefKeywordRole);
					break;
				case UndocumentedExpressionType.RefType:
					WriteKeyword (UndocumentedExpression.ReftypeKeywordRole);
					break;
				case UndocumentedExpressionType.RefValue:
					WriteKeyword (UndocumentedExpression.RefvalueKeywordRole);
					break;
			}
			if (undocumentedExpression.Arguments.Count > 0) {
				Space (policy.SpaceBeforeMethodCallParentheses);
				WriteCommaSeparatedListInParenthesis (undocumentedExpression.Arguments, policy.SpaceWithinMethodCallParentheses);
			}
			EndNode (undocumentedExpression);
		}
		
		public void VisitArrayCreateExpression (ArrayCreateExpression arrayCreateExpression)
		{
			StartNode (arrayCreateExpression);
			WriteKeyword (ArrayCreateExpression.NewKeywordRole);
			arrayCreateExpression.Type.AcceptVisitor (this);
			if (arrayCreateExpression.Arguments.Count > 0)
				WriteCommaSeparatedListInBrackets (arrayCreateExpression.Arguments);
			foreach (var specifier in arrayCreateExpression.AdditionalArraySpecifiers)
				specifier.AcceptVisitor (this);
			arrayCreateExpression.Initializer.AcceptVisitor (this);
			EndNode (arrayCreateExpression);
		}
		
		public void VisitArrayInitializerExpression (ArrayInitializerExpression arrayInitializerExpression)
		{
			StartNode (arrayInitializerExpression);
			// "new List<int> { { 1 } }" and "new List<int> { 1 }" are the same semantically.
			// We also use the same AST for both: we always use two nested ArrayInitializerExpressions
			// for collection initializers, even if the user did not write nested brackets.
			// The output visitor will output nested braces only if they are necessary,
			// or if the braces tokens exist in the AST.
			bool bracesAreOptional = arrayInitializerExpression.Elements.Count == 1
				&& IsObjectOrCollectionInitializer(arrayInitializerExpression.Parent)
				&& !CanBeConfusedWithObjectInitializer(arrayInitializerExpression.Elements.Single());
			if (bracesAreOptional && arrayInitializerExpression.LBraceToken.IsNull) {
				arrayInitializerExpression.Elements.Single().AcceptVisitor (this);
			} else {
				PrintInitializerElements(arrayInitializerExpression.Elements);
			}
			EndNode (arrayInitializerExpression);
		}
		
		bool CanBeConfusedWithObjectInitializer(Expression expr)
		{
			// "int a; new List<int> { a = 1 };" is an object initalizers and invalid, but
			// "int a; new List<int> { { a = 1 } };" is a valid collection initializer.
			AssignmentExpression ae = expr as AssignmentExpression;
			return ae != null && ae.Operator == AssignmentOperatorType.Assign;
		}
		
		bool IsObjectOrCollectionInitializer(AstNode node)
		{
			if (!(node is ArrayInitializerExpression))
				return false;
			if (node.Parent is ObjectCreateExpression)
				return node.Role == ObjectCreateExpression.InitializerRole;
			if (node.Parent is NamedExpression)
				return node.Role == Roles.Expression;
			return false;
		}
		
		void PrintInitializerElements(AstNodeCollection<Expression> elements)
		{
			BraceStyle style;
			if (policy.PlaceArrayInitializersOnNewLine == ArrayInitializerPlacement.AlwaysNewLine)
				style = BraceStyle.NextLine;
			else
				style = BraceStyle.EndOfLine;
			OpenBrace(style);
			bool isFirst = true;
			foreach (AstNode node in elements) {
				if (isFirst) {
					isFirst = false;
				} else {
					Comma(node, noSpaceAfterComma: true);
					NewLine();
				}
				node.AcceptVisitor (this);
			}
			OptionalComma();
			NewLine();
			CloseBrace(style);
		}
		
		public void VisitAsExpression (AsExpression asExpression)
		{
			StartNode (asExpression);
			asExpression.Expression.AcceptVisitor (this);
			Space ();
			WriteKeyword (AsExpression.AsKeywordRole);
			Space ();
			asExpression.Type.AcceptVisitor (this);
			EndNode (asExpression);
		}
		
		public void VisitAssignmentExpression (AssignmentExpression assignmentExpression)
		{
			StartNode (assignmentExpression);
			assignmentExpression.Left.AcceptVisitor (this);
			Space (policy.SpaceAroundAssignment);
			WriteToken (AssignmentExpression.GetOperatorRole (assignmentExpression.Operator));
			Space (policy.SpaceAroundAssignment);
			assignmentExpression.Right.AcceptVisitor (this);
			EndNode (assignmentExpression);
		}
		
		public void VisitBaseReferenceExpression (BaseReferenceExpression baseReferenceExpression)
		{
			StartNode (baseReferenceExpression);
			WriteKeyword ("base", baseReferenceExpression.Role);
			EndNode (baseReferenceExpression);
		}
		
		public void VisitBinaryOperatorExpression (BinaryOperatorExpression binaryOperatorExpression)
		{
			StartNode (binaryOperatorExpression);
			binaryOperatorExpression.Left.AcceptVisitor (this);
			bool spacePolicy;
			switch (binaryOperatorExpression.Operator) {
				case BinaryOperatorType.BitwiseAnd:
				case BinaryOperatorType.BitwiseOr:
				case BinaryOperatorType.ExclusiveOr:
					spacePolicy = policy.SpaceAroundBitwiseOperator;
					break;
				case BinaryOperatorType.ConditionalAnd:
				case BinaryOperatorType.ConditionalOr:
					spacePolicy = policy.SpaceAroundLogicalOperator;
					break;
				case BinaryOperatorType.GreaterThan:
				case BinaryOperatorType.GreaterThanOrEqual:
				case BinaryOperatorType.LessThanOrEqual:
				case BinaryOperatorType.LessThan:
					spacePolicy = policy.SpaceAroundRelationalOperator;
					break;
				case BinaryOperatorType.Equality:
				case BinaryOperatorType.InEquality:
					spacePolicy = policy.SpaceAroundEqualityOperator;
					break;
				case BinaryOperatorType.Add:
				case BinaryOperatorType.Subtract:
					spacePolicy = policy.SpaceAroundAdditiveOperator;
					break;
				case BinaryOperatorType.Multiply:
				case BinaryOperatorType.Divide:
				case BinaryOperatorType.Modulus:
					spacePolicy = policy.SpaceAroundMultiplicativeOperator;
					break;
				case BinaryOperatorType.ShiftLeft:
				case BinaryOperatorType.ShiftRight:
					spacePolicy = policy.SpaceAroundShiftOperator;
					break;
				case BinaryOperatorType.NullCoalescing:
					spacePolicy = true;
					break;
				default:
					throw new NotSupportedException ("Invalid value for BinaryOperatorType");
			}
			Space (spacePolicy);
			WriteToken (BinaryOperatorExpression.GetOperatorRole (binaryOperatorExpression.Operator));
			Space (spacePolicy);
			binaryOperatorExpression.Right.AcceptVisitor (this);
			EndNode (binaryOperatorExpression);
		}
		
		public void VisitCastExpression (CastExpression castExpression)
		{
			StartNode (castExpression);
			LPar ();
			Space (policy.SpacesWithinCastParentheses);
			castExpression.Type.AcceptVisitor (this);
			Space (policy.SpacesWithinCastParentheses);
			RPar ();
			Space (policy.SpaceAfterTypecast);
			castExpression.Expression.AcceptVisitor (this);
			EndNode (castExpression);
		}
		
		public void VisitCheckedExpression (CheckedExpression checkedExpression)
		{
			StartNode (checkedExpression);
			WriteKeyword (CheckedExpression.CheckedKeywordRole);
			LPar ();
			Space (policy.SpacesWithinCheckedExpressionParantheses);
			checkedExpression.Expression.AcceptVisitor (this);
			Space (policy.SpacesWithinCheckedExpressionParantheses);
			RPar ();
			EndNode (checkedExpression);
		}
		
		public void VisitConditionalExpression (ConditionalExpression conditionalExpression)
		{
			StartNode (conditionalExpression);
			conditionalExpression.Condition.AcceptVisitor (this);
			
			Space (policy.SpaceBeforeConditionalOperatorCondition);
			WriteToken (ConditionalExpression.QuestionMarkRole);
			Space (policy.SpaceAfterConditionalOperatorCondition);
			
			conditionalExpression.TrueExpression.AcceptVisitor (this);
			
			Space (policy.SpaceBeforeConditionalOperatorSeparator);
			WriteToken (ConditionalExpression.ColonRole);
			Space (policy.SpaceAfterConditionalOperatorSeparator);
			
			conditionalExpression.FalseExpression.AcceptVisitor (this);
			
			EndNode (conditionalExpression);
		}
		
		public void VisitDefaultValueExpression (DefaultValueExpression defaultValueExpression)
		{
			StartNode (defaultValueExpression);
			
			WriteKeyword (DefaultValueExpression.DefaultKeywordRole);
			LPar ();
			Space (policy.SpacesWithinTypeOfParentheses);
			defaultValueExpression.Type.AcceptVisitor (this);
			Space (policy.SpacesWithinTypeOfParentheses);
			RPar ();
			
			EndNode (defaultValueExpression);
		}
		
		public void VisitDirectionExpression (DirectionExpression directionExpression)
		{
			StartNode (directionExpression);
			
			switch (directionExpression.FieldDirection) {
				case FieldDirection.Out:
					WriteKeyword (DirectionExpression.OutKeywordRole);
					break;
				case FieldDirection.Ref:
					WriteKeyword (DirectionExpression.RefKeywordRole);
					break;
				default:
					throw new NotSupportedException ("Invalid value for FieldDirection");
			}
			Space ();
			directionExpression.Expression.AcceptVisitor (this);
			
			EndNode (directionExpression);
		}
		
		public void VisitIdentifierExpression (IdentifierExpression identifierExpression)
		{
			StartNode (identifierExpression);
			WriteIdentifier (identifierExpression.Identifier);
			WriteTypeArguments (identifierExpression.TypeArguments);
			EndNode (identifierExpression);
		}
		
		public void VisitIndexerExpression (IndexerExpression indexerExpression)
		{
			StartNode (indexerExpression);
			indexerExpression.Target.AcceptVisitor (this);
			Space (policy.SpaceBeforeMethodCallParentheses);
			WriteCommaSeparatedListInBrackets (indexerExpression.Arguments);
			EndNode (indexerExpression);
		}
		
		public void VisitInvocationExpression (InvocationExpression invocationExpression)
		{
			StartNode (invocationExpression);
			invocationExpression.Target.AcceptVisitor (this);
			Space (policy.SpaceBeforeMethodCallParentheses);
			WriteCommaSeparatedListInParenthesis (invocationExpression.Arguments, policy.SpaceWithinMethodCallParentheses);
			EndNode (invocationExpression);
		}
		
		public void VisitIsExpression (IsExpression isExpression)
		{
			StartNode (isExpression);
			isExpression.Expression.AcceptVisitor (this);
			Space ();
			WriteKeyword (IsExpression.IsKeywordRole);
			isExpression.Type.AcceptVisitor (this);
			EndNode (isExpression);
		}
		
		public void VisitLambdaExpression (LambdaExpression lambdaExpression)
		{
			StartNode (lambdaExpression);
			if (lambdaExpression.IsAsync) {
				WriteKeyword (LambdaExpression.AsyncModifierRole);
				Space ();
			}
			if (LambdaNeedsParenthesis (lambdaExpression)) {
				WriteCommaSeparatedListInParenthesis (lambdaExpression.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			} else {
				lambdaExpression.Parameters.Single ().AcceptVisitor (this);
			}
			Space ();
			WriteToken (LambdaExpression.ArrowRole);
			Space ();
			lambdaExpression.Body.AcceptVisitor (this);
			EndNode (lambdaExpression);
		}
		
		bool LambdaNeedsParenthesis (LambdaExpression lambdaExpression)
		{
			if (lambdaExpression.Parameters.Count != 1)
				return true;
			var p = lambdaExpression.Parameters.Single ();
			return !(p.Type.IsNull && p.ParameterModifier == ParameterModifier.None);
		}
		
		public void VisitMemberReferenceExpression (MemberReferenceExpression memberReferenceExpression)
		{
			StartNode (memberReferenceExpression);
			memberReferenceExpression.Target.AcceptVisitor (this);
			WriteToken (Roles.Dot);
			WriteIdentifier (memberReferenceExpression.MemberName);
			WriteTypeArguments (memberReferenceExpression.TypeArguments);
			EndNode (memberReferenceExpression);
		}
		
		public void VisitNamedArgumentExpression (NamedArgumentExpression namedArgumentExpression)
		{
			StartNode (namedArgumentExpression);
			WriteIdentifier (namedArgumentExpression.Identifier);
			WriteToken(Roles.Colon);
			Space ();
			namedArgumentExpression.Expression.AcceptVisitor (this);
			EndNode (namedArgumentExpression);
		}
		
		public void VisitNamedExpression (NamedExpression namedExpression)
		{
			StartNode (namedExpression);
			WriteIdentifier (namedExpression.Identifier);
			Space();
			WriteToken(Roles.Assign);
			Space ();
			namedExpression.Expression.AcceptVisitor (this);
			EndNode (namedExpression);
		}
		
		public void VisitNullReferenceExpression (NullReferenceExpression nullReferenceExpression)
		{
			StartNode (nullReferenceExpression);
			WriteKeyword ("null", nullReferenceExpression.Role);
			EndNode (nullReferenceExpression);
		}
		
		public void VisitObjectCreateExpression (ObjectCreateExpression objectCreateExpression)
		{
			StartNode (objectCreateExpression);
			WriteKeyword (ObjectCreateExpression.NewKeywordRole);
			objectCreateExpression.Type.AcceptVisitor (this);
			bool useParenthesis = objectCreateExpression.Arguments.Any() || objectCreateExpression.Initializer.IsNull;
			// also use parenthesis if there is an '(' token
			if (!objectCreateExpression.LParToken.IsNull)
				useParenthesis = true;
			if (useParenthesis) {
				Space (policy.SpaceBeforeMethodCallParentheses);
				WriteCommaSeparatedListInParenthesis (objectCreateExpression.Arguments, policy.SpaceWithinMethodCallParentheses);
			}
			objectCreateExpression.Initializer.AcceptVisitor (this);
			EndNode (objectCreateExpression);
		}
		
		public void VisitAnonymousTypeCreateExpression (AnonymousTypeCreateExpression anonymousTypeCreateExpression)
		{
			StartNode (anonymousTypeCreateExpression);
			WriteKeyword (AnonymousTypeCreateExpression.NewKeywordRole);
			PrintInitializerElements(anonymousTypeCreateExpression.Initializers);
			EndNode (anonymousTypeCreateExpression);
		}

		public void VisitParenthesizedExpression (ParenthesizedExpression parenthesizedExpression)
		{
			StartNode (parenthesizedExpression);
			LPar ();
			Space (policy.SpacesWithinParentheses);
			parenthesizedExpression.Expression.AcceptVisitor (this);
			Space (policy.SpacesWithinParentheses);
			RPar ();
			EndNode (parenthesizedExpression);
		}
		
		public void VisitPointerReferenceExpression (PointerReferenceExpression pointerReferenceExpression)
		{
			StartNode (pointerReferenceExpression);
			pointerReferenceExpression.Target.AcceptVisitor (this);
			WriteToken (PointerReferenceExpression.ArrowRole);
			WriteIdentifier (pointerReferenceExpression.MemberName);
			WriteTypeArguments (pointerReferenceExpression.TypeArguments);
			EndNode (pointerReferenceExpression);
		}
		
		public void VisitEmptyExpression (EmptyExpression emptyExpression)
		{
			StartNode (emptyExpression);
			EndNode (emptyExpression);
		}

		#region VisitPrimitiveExpression
		public void VisitPrimitiveExpression (PrimitiveExpression primitiveExpression)
		{
			StartNode (primitiveExpression);
			if (!string.IsNullOrEmpty (primitiveExpression.LiteralValue)) {
				formatter.WriteToken (primitiveExpression.LiteralValue);
			} else {
				WritePrimitiveValue (primitiveExpression.Value);
			}
			EndNode (primitiveExpression);
		}
		
		void WritePrimitiveValue (object val)
		{
			if (val == null) {
				// usually NullReferenceExpression should be used for this, but we'll handle it anyways
				WriteKeyword ("null");
				return;
			}
			
			if (val is bool) {
				if ((bool)val) {
					WriteKeyword ("true");
				} else {
					WriteKeyword ("false");
				}
				return;
			}
			
			if (val is string) {
				formatter.WriteToken ("\"" + ConvertString (val.ToString ()) + "\"");
				lastWritten = LastWritten.Other;
			} else if (val is char) {
				formatter.WriteToken ("'" + ConvertCharLiteral ((char)val) + "'");
				lastWritten = LastWritten.Other;
			} else if (val is decimal) {
				formatter.WriteToken (((decimal)val).ToString (NumberFormatInfo.InvariantInfo) + "m");
				lastWritten = LastWritten.Other;
			} else if (val is float) {
				float f = (float)val;
				if (float.IsInfinity (f) || float.IsNaN (f)) {
					// Strictly speaking, these aren't PrimitiveExpressions;
					// but we still support writing these to make life easier for code generators.
					WriteKeyword ("float");
					WriteToken (Roles.Dot);
					if (float.IsPositiveInfinity (f))
						WriteIdentifier ("PositiveInfinity");
					else if (float.IsNegativeInfinity (f))
						WriteIdentifier ("NegativeInfinity");
					else
						WriteIdentifier ("NaN");
					return;
				}
				formatter.WriteToken (f.ToString ("R", NumberFormatInfo.InvariantInfo) + "f");
				lastWritten = LastWritten.Other;
			} else if (val is double) {
				double f = (double)val;
				if (double.IsInfinity (f) || double.IsNaN (f)) {
					// Strictly speaking, these aren't PrimitiveExpressions;
					// but we still support writing these to make life easier for code generators.
					WriteKeyword ("double");
					WriteToken (Roles.Dot);
					if (double.IsPositiveInfinity (f))
						WriteIdentifier ("PositiveInfinity");
					else if (double.IsNegativeInfinity (f))
						WriteIdentifier ("NegativeInfinity");
					else
						WriteIdentifier ("NaN");
					return;
				}
				string number = f.ToString ("R", NumberFormatInfo.InvariantInfo);
				if (number.IndexOf ('.') < 0 && number.IndexOf ('E') < 0)
					number += ".0";
				formatter.WriteToken (number);
				// needs space if identifier follows number; this avoids mistaking the following identifier as type suffix
				lastWritten = LastWritten.KeywordOrIdentifier;
			} else if (val is IFormattable) {
				StringBuilder b = new StringBuilder ();
//				if (primitiveExpression.LiteralFormat == LiteralFormat.HexadecimalNumber) {
//					b.Append("0x");
//					b.Append(((IFormattable)val).ToString("x", NumberFormatInfo.InvariantInfo));
//				} else {
				b.Append (((IFormattable)val).ToString (null, NumberFormatInfo.InvariantInfo));
//				}
				if (val is uint || val is ulong) {
					b.Append ("u");
				}
				if (val is long || val is ulong) {
					b.Append ("L");
				}
				formatter.WriteToken (b.ToString ());
				// needs space if identifier follows number; this avoids mistaking the following identifier as type suffix
				lastWritten = LastWritten.KeywordOrIdentifier;
			} else {
				formatter.WriteToken (val.ToString ());
				lastWritten = LastWritten.Other;
			}
		}
		
		static string ConvertCharLiteral (char ch)
		{
			if (ch == '\'')
				return "\\'";
			return ConvertChar (ch);
		}
		
		/// <summary>
		/// Gets the escape sequence for the specified character.
		/// </summary>
		/// <remarks>This method does not convert ' or ".</remarks>
		public static string ConvertChar(char ch)
		{
			switch (ch) {
				case '\\':
					return "\\\\";
				case '\0':
					return "\\0";
				case '\a':
					return "\\a";
				case '\b':
					return "\\b";
				case '\f':
					return "\\f";
				case '\n':
					return "\\n";
				case '\r':
					return "\\r";
				case '\t':
					return "\\t";
				case '\v':
					return "\\v";
				default:
					if (char.IsControl(ch) || char.IsSurrogate(ch) ||
					    // print all uncommon white spaces as numbers
					    (char.IsWhiteSpace(ch) && ch != ' ')) {
						return "\\u" + ((int)ch).ToString ("x4");
					} else {
						return ch.ToString ();
					}
			}
		}
		
		/// <summary>
		/// Converts special characters to escape sequences within the given string.
		/// </summary>
		public static string ConvertString(string str)
		{
			StringBuilder sb = new StringBuilder ();
			foreach (char ch in str) {
				if (ch == '"')
					sb.Append ("\\\"");
				else
					sb.Append (ConvertChar (ch));
			}
			return sb.ToString ();
		}

		#endregion
		
		public void VisitSizeOfExpression (SizeOfExpression sizeOfExpression)
		{
			StartNode (sizeOfExpression);
			
			WriteKeyword (SizeOfExpression.SizeofKeywordRole);
			LPar ();
			Space (policy.SpacesWithinSizeOfParentheses);
			sizeOfExpression.Type.AcceptVisitor (this);
			Space (policy.SpacesWithinSizeOfParentheses);
			RPar ();
			
			EndNode (sizeOfExpression);
		}
		
		public void VisitStackAllocExpression (StackAllocExpression stackAllocExpression)
		{
			StartNode (stackAllocExpression);
			WriteKeyword (StackAllocExpression.StackallocKeywordRole);
			stackAllocExpression.Type.AcceptVisitor (this);
			WriteCommaSeparatedListInBrackets (new[] { stackAllocExpression.CountExpression });
			EndNode (stackAllocExpression);
		}
		
		public void VisitThisReferenceExpression (ThisReferenceExpression thisReferenceExpression)
		{
			StartNode (thisReferenceExpression);
			WriteKeyword ("this", thisReferenceExpression.Role);
			EndNode (thisReferenceExpression);
		}
		
		public void VisitTypeOfExpression (TypeOfExpression typeOfExpression)
		{
			StartNode (typeOfExpression);
			
			WriteKeyword (TypeOfExpression.TypeofKeywordRole);
			LPar ();
			Space (policy.SpacesWithinTypeOfParentheses);
			typeOfExpression.Type.AcceptVisitor (this);
			Space (policy.SpacesWithinTypeOfParentheses);
			RPar ();
			
			EndNode (typeOfExpression);
		}
		
		public void VisitTypeReferenceExpression (TypeReferenceExpression typeReferenceExpression)
		{
			StartNode (typeReferenceExpression);
			typeReferenceExpression.Type.AcceptVisitor (this);
			EndNode (typeReferenceExpression);
		}
		
		public void VisitUnaryOperatorExpression (UnaryOperatorExpression unaryOperatorExpression)
		{
			StartNode (unaryOperatorExpression);
			UnaryOperatorType opType = unaryOperatorExpression.Operator;
			var opSymbol = UnaryOperatorExpression.GetOperatorRole (opType);
			if (opType == UnaryOperatorType.Await) {
				WriteKeyword (opSymbol);
			} else if (!(opType == UnaryOperatorType.PostIncrement || opType == UnaryOperatorType.PostDecrement)) {
				WriteToken (opSymbol);
			}
			unaryOperatorExpression.Expression.AcceptVisitor (this);
			if (opType == UnaryOperatorType.PostIncrement || opType == UnaryOperatorType.PostDecrement)
				WriteToken (opSymbol);
			EndNode (unaryOperatorExpression);
		}
		
		public void VisitUncheckedExpression (UncheckedExpression uncheckedExpression)
		{
			StartNode (uncheckedExpression);
			WriteKeyword (UncheckedExpression.UncheckedKeywordRole);
			LPar ();
			Space (policy.SpacesWithinCheckedExpressionParantheses);
			uncheckedExpression.Expression.AcceptVisitor (this);
			Space (policy.SpacesWithinCheckedExpressionParantheses);
			RPar ();
			EndNode (uncheckedExpression);
		}

		#endregion
		
		#region Query Expressions
		public void VisitQueryExpression (QueryExpression queryExpression)
		{
			StartNode (queryExpression);
			bool indent = !(queryExpression.Parent is QueryContinuationClause);
			if (indent) {
				formatter.Indent();
				NewLine();
			}
			bool first = true;
			foreach (var clause in queryExpression.Clauses) {
				if (first) {
					first = false;
				} else {
					if (!(clause is QueryContinuationClause))
						NewLine ();
				}
				clause.AcceptVisitor (this);
			}
			if (indent)
				formatter.Unindent();
			EndNode (queryExpression);
		}
		
		public void VisitQueryContinuationClause (QueryContinuationClause queryContinuationClause)
		{
			StartNode (queryContinuationClause);
			queryContinuationClause.PrecedingQuery.AcceptVisitor (this);
			Space ();
			WriteKeyword (QueryContinuationClause.IntoKeywordRole);
			Space ();
			WriteIdentifier (queryContinuationClause.Identifier);
			EndNode (queryContinuationClause);
		}
		
		public void VisitQueryFromClause (QueryFromClause queryFromClause)
		{
			StartNode (queryFromClause);
			WriteKeyword (QueryFromClause.FromKeywordRole);
			queryFromClause.Type.AcceptVisitor (this);
			Space ();
			WriteIdentifier (queryFromClause.Identifier);
			Space ();
			WriteKeyword (QueryFromClause.InKeywordRole);
			Space ();
			queryFromClause.Expression.AcceptVisitor (this);
			EndNode (queryFromClause);
		}
		
		public void VisitQueryLetClause (QueryLetClause queryLetClause)
		{
			StartNode (queryLetClause);
			WriteKeyword (QueryLetClause.LetKeywordRole);
			Space ();
			WriteIdentifier (queryLetClause.Identifier);
			Space (policy.SpaceAroundAssignment);
			WriteToken (Roles.Assign);
			Space (policy.SpaceAroundAssignment);
			queryLetClause.Expression.AcceptVisitor (this);
			EndNode (queryLetClause);
		}
		
		public void VisitQueryWhereClause (QueryWhereClause queryWhereClause)
		{
			StartNode (queryWhereClause);
			WriteKeyword (QueryWhereClause.WhereKeywordRole);
			Space ();
			queryWhereClause.Condition.AcceptVisitor (this);
			EndNode (queryWhereClause);
		}
		
		public void VisitQueryJoinClause (QueryJoinClause queryJoinClause)
		{
			StartNode (queryJoinClause);
			WriteKeyword (QueryJoinClause.JoinKeywordRole);
			queryJoinClause.Type.AcceptVisitor (this);
			Space ();
			WriteIdentifier (queryJoinClause.JoinIdentifier, QueryJoinClause.JoinIdentifierRole);
			Space ();
			WriteKeyword (QueryJoinClause.InKeywordRole);
			Space ();
			queryJoinClause.InExpression.AcceptVisitor (this);
			Space ();
			WriteKeyword (QueryJoinClause.OnKeywordRole);
			Space ();
			queryJoinClause.OnExpression.AcceptVisitor (this);
			Space ();
			WriteKeyword (QueryJoinClause.EqualsKeywordRole);
			Space ();
			queryJoinClause.EqualsExpression.AcceptVisitor (this);
			if (queryJoinClause.IsGroupJoin) {
				Space ();
				WriteKeyword (QueryJoinClause.IntoKeywordRole);
				WriteIdentifier (queryJoinClause.IntoIdentifier, QueryJoinClause.IntoIdentifierRole);
			}
			EndNode (queryJoinClause);
		}
		
		public void VisitQueryOrderClause (QueryOrderClause queryOrderClause)
		{
			StartNode (queryOrderClause);
			WriteKeyword (QueryOrderClause.OrderbyKeywordRole);
			Space ();
			WriteCommaSeparatedList (queryOrderClause.Orderings);
			EndNode (queryOrderClause);
		}
		
		public void VisitQueryOrdering (QueryOrdering queryOrdering)
		{
			StartNode (queryOrdering);
			queryOrdering.Expression.AcceptVisitor (this);
			switch (queryOrdering.Direction) {
				case QueryOrderingDirection.Ascending:
					Space ();
					WriteKeyword (QueryOrdering.AscendingKeywordRole);
					break;
				case QueryOrderingDirection.Descending:
					Space ();
					WriteKeyword (QueryOrdering.DescendingKeywordRole);
					break;
			}
			EndNode (queryOrdering);
		}
		
		public void VisitQuerySelectClause (QuerySelectClause querySelectClause)
		{
			StartNode (querySelectClause);
			WriteKeyword (QuerySelectClause.SelectKeywordRole);
			Space ();
			querySelectClause.Expression.AcceptVisitor (this);
			EndNode (querySelectClause);
		}
		
		public void VisitQueryGroupClause (QueryGroupClause queryGroupClause)
		{
			StartNode (queryGroupClause);
			WriteKeyword (QueryGroupClause.GroupKeywordRole);
			Space ();
			queryGroupClause.Projection.AcceptVisitor (this);
			Space ();
			WriteKeyword (QueryGroupClause.ByKeywordRole);
			Space ();
			queryGroupClause.Key.AcceptVisitor (this);
			EndNode (queryGroupClause);
		}

		#endregion
		
		#region GeneralScope
		public void VisitAttribute (Attribute attribute)
		{
			StartNode (attribute);
			attribute.Type.AcceptVisitor (this);
			if (attribute.Arguments.Count != 0 || !attribute.GetChildByRole (Roles.LPar).IsNull) {
				Space (policy.SpaceBeforeMethodCallParentheses);
				WriteCommaSeparatedListInParenthesis (attribute.Arguments, policy.SpaceWithinMethodCallParentheses);
			}
			EndNode (attribute);
		}
		
		public void VisitAttributeSection (AttributeSection attributeSection)
		{
			StartNode (attributeSection);
			WriteToken (Roles.LBracket);
			if (!string.IsNullOrEmpty (attributeSection.AttributeTarget)) {
				WriteToken (attributeSection.AttributeTarget, Roles.AttributeTargetRole);
				WriteToken (Roles.Colon);
				Space ();
			}
			WriteCommaSeparatedList (attributeSection.Attributes);
			WriteToken (Roles.RBracket);
			if (attributeSection.Parent is ParameterDeclaration || attributeSection.Parent is TypeParameterDeclaration)
				Space ();
			else
				NewLine ();
			EndNode (attributeSection);
		}
		
		public void VisitDelegateDeclaration (DelegateDeclaration delegateDeclaration)
		{
			StartNode (delegateDeclaration);
			WriteAttributes (delegateDeclaration.Attributes);
			WriteModifiers (delegateDeclaration.ModifierTokens);
			WriteKeyword (Roles.DelegateKeyword);
			delegateDeclaration.ReturnType.AcceptVisitor (this);
			Space ();
			WriteIdentifier (delegateDeclaration.Name);
			WriteTypeParameters (delegateDeclaration.TypeParameters);
			Space (policy.SpaceBeforeDelegateDeclarationParentheses);
			WriteCommaSeparatedListInParenthesis (delegateDeclaration.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			foreach (Constraint constraint in delegateDeclaration.Constraints) {
				constraint.AcceptVisitor (this);
			}
			Semicolon ();
			EndNode (delegateDeclaration);
		}
		
		public void VisitNamespaceDeclaration(NamespaceDeclaration namespaceDeclaration)
		{
			StartNode(namespaceDeclaration);
			WriteKeyword(Roles.NamespaceKeyword);
			WriteQualifiedIdentifier (namespaceDeclaration.Identifiers);
			OpenBrace (policy.NamespaceBraceStyle);
			foreach (var member in namespaceDeclaration.Members)
				member.AcceptVisitor (this);
			CloseBrace (policy.NamespaceBraceStyle);
			OptionalSemicolon ();
			NewLine ();
			EndNode (namespaceDeclaration);
		}
		
		public void VisitTypeDeclaration(TypeDeclaration typeDeclaration)
		{
			StartNode(typeDeclaration);
			WriteAttributes(typeDeclaration.Attributes);
			WriteModifiers(typeDeclaration.ModifierTokens);
			BraceStyle braceStyle;
			switch (typeDeclaration.ClassType) {
				case ClassType.Enum:
					WriteKeyword(Roles.EnumKeyword);
					braceStyle = policy.EnumBraceStyle;
					break;
				case ClassType.Interface:
					WriteKeyword(Roles.InterfaceKeyword);
					braceStyle = policy.InterfaceBraceStyle;
					break;
				case ClassType.Struct:
					WriteKeyword(Roles.StructKeyword);
					braceStyle = policy.StructBraceStyle;
					break;
				default:
					WriteKeyword(Roles.ClassKeyword);
					braceStyle = policy.ClassBraceStyle;
					break;
			}
			WriteIdentifier(typeDeclaration.Name);
			WriteTypeParameters(typeDeclaration.TypeParameters);
			if (typeDeclaration.BaseTypes.Any()) {
				Space();
				WriteToken(Roles.Colon);
				Space ();
				WriteCommaSeparatedList (typeDeclaration.BaseTypes);
			}
			foreach (Constraint constraint in typeDeclaration.Constraints) {
				constraint.AcceptVisitor (this);
			}
			OpenBrace (braceStyle);
			if (typeDeclaration.ClassType == ClassType.Enum) {
				bool first = true;
				foreach (var member in typeDeclaration.Members) {
					if (first) {
						first = false;
					} else {
						Comma (member, noSpaceAfterComma: true);
						NewLine ();
					}
					member.AcceptVisitor (this);
				}
				OptionalComma();
				NewLine ();
			} else {
				foreach (var member in typeDeclaration.Members) {
					member.AcceptVisitor (this);
				}
			}
			CloseBrace (braceStyle);
			OptionalSemicolon ();
			NewLine ();
			EndNode (typeDeclaration);
		}
		
		public void VisitUsingAliasDeclaration (UsingAliasDeclaration usingAliasDeclaration)
		{
			StartNode (usingAliasDeclaration);
			WriteKeyword (UsingAliasDeclaration.UsingKeywordRole);
			WriteIdentifier (usingAliasDeclaration.Alias, UsingAliasDeclaration.AliasRole);
			Space (policy.SpaceAroundEqualityOperator);
			WriteToken (Roles.Assign);
			Space (policy.SpaceAroundEqualityOperator);
			usingAliasDeclaration.Import.AcceptVisitor (this);
			Semicolon ();
			EndNode (usingAliasDeclaration);
		}
		
		public void VisitUsingDeclaration (UsingDeclaration usingDeclaration)
		{
			StartNode (usingDeclaration);
			WriteKeyword (UsingDeclaration.UsingKeywordRole);
			usingDeclaration.Import.AcceptVisitor (this);
			Semicolon ();
			EndNode (usingDeclaration);
		}
		
		public void VisitExternAliasDeclaration(ExternAliasDeclaration externAliasDeclaration)
		{
			StartNode(externAliasDeclaration);
			WriteKeyword(Roles.ExternKeyword);
			Space ();
			WriteKeyword (Roles.AliasKeyword);
			Space ();
			externAliasDeclaration.NameToken.AcceptVisitor (this);
			Semicolon ();
			EndNode (externAliasDeclaration);
		}

		#endregion
		
		#region Statements
		public void VisitBlockStatement (BlockStatement blockStatement)
		{
			StartNode (blockStatement);
			BraceStyle style;
			if (blockStatement.Parent is AnonymousMethodExpression || blockStatement.Parent is LambdaExpression) {
				style = policy.AnonymousMethodBraceStyle;
			} else if (blockStatement.Parent is ConstructorDeclaration) {
				style = policy.ConstructorBraceStyle;
			} else if (blockStatement.Parent is DestructorDeclaration) {
				style = policy.DestructorBraceStyle;
			} else if (blockStatement.Parent is MethodDeclaration) {
				style = policy.MethodBraceStyle;
			} else if (blockStatement.Parent is Accessor) {
				if (blockStatement.Parent.Role == PropertyDeclaration.GetterRole)
					style = policy.PropertyGetBraceStyle;
				else if (blockStatement.Parent.Role == PropertyDeclaration.SetterRole)
					style = policy.PropertySetBraceStyle;
				else if (blockStatement.Parent.Role == CustomEventDeclaration.AddAccessorRole)
					style = policy.EventAddBraceStyle;
				else if (blockStatement.Parent.Role == CustomEventDeclaration.RemoveAccessorRole)
					style = policy.EventRemoveBraceStyle;
				else
					style = policy.StatementBraceStyle;
			} else {
				style = policy.StatementBraceStyle;
			}
			OpenBrace (style);
			foreach (var node in blockStatement.Statements) {
				node.AcceptVisitor (this);
			}
			CloseBrace (style);
			NewLine ();
			EndNode (blockStatement);
		}
		
		public void VisitBreakStatement (BreakStatement breakStatement)
		{
			StartNode (breakStatement);
			WriteKeyword ("break");
			Semicolon ();
			EndNode (breakStatement);
		}
		
		public void VisitCheckedStatement (CheckedStatement checkedStatement)
		{
			StartNode (checkedStatement);
			WriteKeyword (CheckedStatement.CheckedKeywordRole);
			checkedStatement.Body.AcceptVisitor (this);
			EndNode (checkedStatement);
		}
		
		public void VisitContinueStatement (ContinueStatement continueStatement)
		{
			StartNode (continueStatement);
			WriteKeyword ("continue");
			Semicolon ();
			EndNode (continueStatement);
		}
		
		public void VisitDoWhileStatement (DoWhileStatement doWhileStatement)
		{
			StartNode (doWhileStatement);
			WriteKeyword (DoWhileStatement.DoKeywordRole);
			WriteEmbeddedStatement (doWhileStatement.EmbeddedStatement);
			WriteKeyword (DoWhileStatement.WhileKeywordRole);
			Space (policy.SpaceBeforeWhileParentheses);
			LPar ();
			Space (policy.SpacesWithinWhileParentheses);
			doWhileStatement.Condition.AcceptVisitor (this);
			Space (policy.SpacesWithinWhileParentheses);
			RPar ();
			Semicolon ();
			EndNode (doWhileStatement);
		}
		
		public void VisitEmptyStatement (EmptyStatement emptyStatement)
		{
			StartNode (emptyStatement);
			Semicolon ();
			EndNode (emptyStatement);
		}
		
		public void VisitExpressionStatement (ExpressionStatement expressionStatement)
		{
			StartNode (expressionStatement);
			expressionStatement.Expression.AcceptVisitor (this);
			Semicolon ();
			EndNode (expressionStatement);
		}
		
		public void VisitFixedStatement (FixedStatement fixedStatement)
		{
			StartNode (fixedStatement);
			WriteKeyword (FixedStatement.FixedKeywordRole);
			Space (policy.SpaceBeforeUsingParentheses);
			LPar ();
			Space (policy.SpacesWithinUsingParentheses);
			fixedStatement.Type.AcceptVisitor (this);
			Space ();
			WriteCommaSeparatedList (fixedStatement.Variables);
			Space (policy.SpacesWithinUsingParentheses);
			RPar ();
			WriteEmbeddedStatement (fixedStatement.EmbeddedStatement);
			EndNode (fixedStatement);
		}
		
		public void VisitForeachStatement (ForeachStatement foreachStatement)
		{
			StartNode (foreachStatement);
			WriteKeyword (ForeachStatement.ForeachKeywordRole);
			Space (policy.SpaceBeforeForeachParentheses);
			LPar ();
			Space (policy.SpacesWithinForeachParentheses);
			foreachStatement.VariableType.AcceptVisitor (this);
			Space ();
			WriteIdentifier (foreachStatement.VariableName);
			WriteKeyword (ForeachStatement.InKeywordRole);
			Space ();
			foreachStatement.InExpression.AcceptVisitor (this);
			Space (policy.SpacesWithinForeachParentheses);
			RPar ();
			WriteEmbeddedStatement (foreachStatement.EmbeddedStatement);
			EndNode (foreachStatement);
		}
		
		public void VisitForStatement (ForStatement forStatement)
		{
			StartNode (forStatement);
			WriteKeyword (ForStatement.ForKeywordRole);
			Space (policy.SpaceBeforeForParentheses);
			LPar ();
			Space (policy.SpacesWithinForParentheses);
			
			WriteCommaSeparatedList (forStatement.Initializers);
			Space (policy.SpaceBeforeForSemicolon);
			WriteToken (Roles.Semicolon);
			Space (policy.SpaceAfterForSemicolon);
			
			forStatement.Condition.AcceptVisitor (this);
			Space (policy.SpaceBeforeForSemicolon);
			WriteToken (Roles.Semicolon);
			Space (policy.SpaceAfterForSemicolon);
			
			WriteCommaSeparatedList (forStatement.Iterators);
			
			Space (policy.SpacesWithinForParentheses);
			RPar ();
			WriteEmbeddedStatement (forStatement.EmbeddedStatement);
			EndNode (forStatement);
		}
		
		public void VisitGotoCaseStatement (GotoCaseStatement gotoCaseStatement)
		{
			StartNode (gotoCaseStatement);
			WriteKeyword (GotoCaseStatement.GotoKeywordRole);
			WriteKeyword (GotoCaseStatement.CaseKeywordRole);
			Space ();
			gotoCaseStatement.LabelExpression.AcceptVisitor (this);
			Semicolon ();
			EndNode (gotoCaseStatement);
		}
		
		public void VisitGotoDefaultStatement (GotoDefaultStatement gotoDefaultStatement)
		{
			StartNode (gotoDefaultStatement);
			WriteKeyword (GotoDefaultStatement.GotoKeywordRole);
			WriteKeyword (GotoDefaultStatement.DefaultKeywordRole);
			Semicolon ();
			EndNode (gotoDefaultStatement);
		}
		
		public void VisitGotoStatement (GotoStatement gotoStatement)
		{
			StartNode (gotoStatement);
			WriteKeyword (GotoStatement.GotoKeywordRole);
			WriteIdentifier (gotoStatement.Label);
			Semicolon ();
			EndNode (gotoStatement);
		}
		
		public void VisitIfElseStatement (IfElseStatement ifElseStatement)
		{
			StartNode (ifElseStatement);
			WriteKeyword (IfElseStatement.IfKeywordRole);
			Space (policy.SpaceBeforeIfParentheses);
			LPar ();
			Space (policy.SpacesWithinIfParentheses);
			ifElseStatement.Condition.AcceptVisitor (this);
			Space (policy.SpacesWithinIfParentheses);
			RPar ();
			WriteEmbeddedStatement (ifElseStatement.TrueStatement);
			if (!ifElseStatement.FalseStatement.IsNull) {
				WriteKeyword (IfElseStatement.ElseKeywordRole);
				WriteEmbeddedStatement (ifElseStatement.FalseStatement);
			}
			EndNode (ifElseStatement);
		}
		
		public void VisitLabelStatement (LabelStatement labelStatement)
		{
			StartNode (labelStatement);
			WriteIdentifier (labelStatement.Label);
			WriteToken (Roles.Colon);
			bool foundLabelledStatement = false;
			for (AstNode tmp = labelStatement.NextSibling; tmp != null; tmp = tmp.NextSibling) {
				if (tmp.Role == labelStatement.Role) {
					foundLabelledStatement = true;
				}
			}
			if (!foundLabelledStatement) {
				// introduce an EmptyStatement so that the output becomes syntactically valid
				WriteToken(Roles.Semicolon);
			}
			NewLine ();
			EndNode (labelStatement);
		}
		
		public void VisitLockStatement (LockStatement lockStatement)
		{
			StartNode (lockStatement);
			WriteKeyword (LockStatement.LockKeywordRole);
			Space (policy.SpaceBeforeLockParentheses);
			LPar ();
			Space (policy.SpacesWithinLockParentheses);
			lockStatement.Expression.AcceptVisitor (this);
			Space (policy.SpacesWithinLockParentheses);
			RPar ();
			WriteEmbeddedStatement (lockStatement.EmbeddedStatement);
			EndNode (lockStatement);
		}
		
		public void VisitReturnStatement (ReturnStatement returnStatement)
		{
			StartNode (returnStatement);
			WriteKeyword (ReturnStatement.ReturnKeywordRole);
			if (!returnStatement.Expression.IsNull) {
				Space ();
				returnStatement.Expression.AcceptVisitor (this);
			}
			Semicolon ();
			EndNode (returnStatement);
		}
		
		public void VisitSwitchStatement (SwitchStatement switchStatement)
		{
			StartNode (switchStatement);
			WriteKeyword (SwitchStatement.SwitchKeywordRole);
			Space (policy.SpaceBeforeSwitchParentheses);
			LPar ();
			Space (policy.SpacesWithinSwitchParentheses);
			switchStatement.Expression.AcceptVisitor (this);
			Space (policy.SpacesWithinSwitchParentheses);
			RPar ();
			OpenBrace (policy.StatementBraceStyle);
			if (!policy.IndentSwitchBody)
				formatter.Unindent ();
			
			foreach (var section in switchStatement.SwitchSections)
				section.AcceptVisitor (this);
			
			if (!policy.IndentSwitchBody)
				formatter.Indent ();
			CloseBrace (policy.StatementBraceStyle);
			NewLine ();
			EndNode (switchStatement);
		}
		
		public void VisitSwitchSection (SwitchSection switchSection)
		{
			StartNode (switchSection);
			bool first = true;
			foreach (var label in switchSection.CaseLabels) {
				if (!first)
					NewLine ();
				label.AcceptVisitor (this);
				first = false;
			}
			if (policy.IndentCaseBody)
				formatter.Indent ();
			
			foreach (var statement in switchSection.Statements) {
				NewLine ();
				statement.AcceptVisitor (this);
			}
			
			if (policy.IndentCaseBody)
				formatter.Unindent ();
			
			EndNode (switchSection);
		}
		
		public void VisitCaseLabel (CaseLabel caseLabel)
		{
			StartNode (caseLabel);
			if (caseLabel.Expression.IsNull) {
				WriteKeyword (CaseLabel.DefaultKeywordRole);
			} else {
				WriteKeyword (CaseLabel.CaseKeywordRole);
				Space ();
				caseLabel.Expression.AcceptVisitor (this);
			}
			WriteToken (Roles.Colon);
			EndNode (caseLabel);
		}
		
		public void VisitThrowStatement (ThrowStatement throwStatement)
		{
			StartNode (throwStatement);
			WriteKeyword (ThrowStatement.ThrowKeywordRole);
			if (!throwStatement.Expression.IsNull) {
				Space ();
				throwStatement.Expression.AcceptVisitor (this);
			}
			Semicolon ();
			EndNode (throwStatement);
		}
		
		public void VisitTryCatchStatement (TryCatchStatement tryCatchStatement)
		{
			StartNode (tryCatchStatement);
			WriteKeyword (TryCatchStatement.TryKeywordRole);
			tryCatchStatement.TryBlock.AcceptVisitor (this);
			foreach (var catchClause in tryCatchStatement.CatchClauses)
				catchClause.AcceptVisitor (this);
			if (!tryCatchStatement.FinallyBlock.IsNull) {
				WriteKeyword (TryCatchStatement.FinallyKeywordRole);
				tryCatchStatement.FinallyBlock.AcceptVisitor (this);
			}
			EndNode (tryCatchStatement);
		}
		
		public void VisitCatchClause (CatchClause catchClause)
		{
			StartNode (catchClause);
			WriteKeyword (CatchClause.CatchKeywordRole);
			if (!catchClause.Type.IsNull) {
				Space (policy.SpaceBeforeCatchParentheses);
				LPar ();
				Space (policy.SpacesWithinCatchParentheses);
				catchClause.Type.AcceptVisitor (this);
				if (!string.IsNullOrEmpty(catchClause.VariableName)) {
					Space ();
					WriteIdentifier (catchClause.VariableName);
				}
				Space (policy.SpacesWithinCatchParentheses);
				RPar ();
			}
			catchClause.Body.AcceptVisitor (this);
			EndNode (catchClause);
		}
		
		public void VisitUncheckedStatement (UncheckedStatement uncheckedStatement)
		{
			StartNode (uncheckedStatement);
			WriteKeyword (UncheckedStatement.UncheckedKeywordRole);
			uncheckedStatement.Body.AcceptVisitor (this);
			EndNode (uncheckedStatement);
		}
		
		public void VisitUnsafeStatement (UnsafeStatement unsafeStatement)
		{
			StartNode (unsafeStatement);
			WriteKeyword (UnsafeStatement.UnsafeKeywordRole);
			unsafeStatement.Body.AcceptVisitor (this);
			EndNode (unsafeStatement);
		}
		
		public void VisitUsingStatement (UsingStatement usingStatement)
		{
			StartNode (usingStatement);
			WriteKeyword (UsingStatement.UsingKeywordRole);
			Space (policy.SpaceBeforeUsingParentheses);
			LPar ();
			Space (policy.SpacesWithinUsingParentheses);
			
			usingStatement.ResourceAcquisition.AcceptVisitor (this);
			
			Space (policy.SpacesWithinUsingParentheses);
			RPar ();
			
			WriteEmbeddedStatement (usingStatement.EmbeddedStatement);
			
			EndNode (usingStatement);
		}
		
		public void VisitVariableDeclarationStatement (VariableDeclarationStatement variableDeclarationStatement)
		{
			StartNode (variableDeclarationStatement);
			WriteModifiers (variableDeclarationStatement.GetChildrenByRole (VariableDeclarationStatement.ModifierRole));
			variableDeclarationStatement.Type.AcceptVisitor (this);
			Space ();
			WriteCommaSeparatedList (variableDeclarationStatement.Variables);
			Semicolon ();
			EndNode (variableDeclarationStatement);
		}
		
		public void VisitWhileStatement (WhileStatement whileStatement)
		{
			StartNode (whileStatement);
			WriteKeyword (WhileStatement.WhileKeywordRole);
			Space (policy.SpaceBeforeWhileParentheses);
			LPar ();
			Space (policy.SpacesWithinWhileParentheses);
			whileStatement.Condition.AcceptVisitor (this);
			Space (policy.SpacesWithinWhileParentheses);
			RPar ();
			WriteEmbeddedStatement (whileStatement.EmbeddedStatement);
			EndNode (whileStatement);
		}
		
		public void VisitYieldBreakStatement (YieldBreakStatement yieldBreakStatement)
		{
			StartNode (yieldBreakStatement);
			WriteKeyword (YieldBreakStatement.YieldKeywordRole);
			WriteKeyword (YieldBreakStatement.BreakKeywordRole);
			Semicolon ();
			EndNode (yieldBreakStatement);
		}
		
		public void VisitYieldReturnStatement (YieldReturnStatement yieldReturnStatement)
		{
			StartNode (yieldReturnStatement);
			WriteKeyword (YieldReturnStatement.YieldKeywordRole);
			WriteKeyword (YieldReturnStatement.ReturnKeywordRole);
			Space ();
			yieldReturnStatement.Expression.AcceptVisitor (this);
			Semicolon ();
			EndNode (yieldReturnStatement);
		}

		#endregion
		
		#region TypeMembers
		public void VisitAccessor (Accessor accessor)
		{
			StartNode (accessor);
			WriteAttributes (accessor.Attributes);
			WriteModifiers (accessor.ModifierTokens);
			if (accessor.Role == PropertyDeclaration.GetterRole) {
				WriteKeyword ("get");
			} else if (accessor.Role == PropertyDeclaration.SetterRole) {
				WriteKeyword ("set");
			} else if (accessor.Role == CustomEventDeclaration.AddAccessorRole) {
				WriteKeyword ("add");
			} else if (accessor.Role == CustomEventDeclaration.RemoveAccessorRole) {
				WriteKeyword ("remove");
			}
			WriteMethodBody (accessor.Body);
			EndNode (accessor);
		}
		
		public void VisitConstructorDeclaration (ConstructorDeclaration constructorDeclaration)
		{
			StartNode (constructorDeclaration);
			WriteAttributes (constructorDeclaration.Attributes);
			WriteModifiers (constructorDeclaration.ModifierTokens);
			TypeDeclaration type = constructorDeclaration.Parent as TypeDeclaration;
			WriteIdentifier (type != null ? type.Name : constructorDeclaration.Name);
			Space (policy.SpaceBeforeConstructorDeclarationParentheses);
			WriteCommaSeparatedListInParenthesis (constructorDeclaration.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			if (!constructorDeclaration.Initializer.IsNull) {
				Space ();
				constructorDeclaration.Initializer.AcceptVisitor (this);
			}
			WriteMethodBody (constructorDeclaration.Body);
			EndNode (constructorDeclaration);
		}
		
		public void VisitConstructorInitializer (ConstructorInitializer constructorInitializer)
		{
			StartNode (constructorInitializer);
			WriteToken (Roles.Colon);
			Space ();
			if (constructorInitializer.ConstructorInitializerType == ConstructorInitializerType.This) {
				WriteKeyword (ConstructorInitializer.ThisKeywordRole);
			} else {
				WriteKeyword (ConstructorInitializer.BaseKeywordRole);
			}
			Space (policy.SpaceBeforeMethodCallParentheses);
			WriteCommaSeparatedListInParenthesis (constructorInitializer.Arguments, policy.SpaceWithinMethodCallParentheses);
			EndNode (constructorInitializer);
		}
		
		public void VisitDestructorDeclaration (DestructorDeclaration destructorDeclaration)
		{
			StartNode (destructorDeclaration);
			WriteAttributes (destructorDeclaration.Attributes);
			WriteModifiers (destructorDeclaration.ModifierTokens);
			WriteToken (DestructorDeclaration.TildeRole);
			TypeDeclaration type = destructorDeclaration.Parent as TypeDeclaration;
			WriteIdentifier (type != null ? type.Name : destructorDeclaration.Name);
			Space (policy.SpaceBeforeConstructorDeclarationParentheses);
			LPar ();
			RPar ();
			WriteMethodBody (destructorDeclaration.Body);
			EndNode (destructorDeclaration);
		}
		
		public void VisitEnumMemberDeclaration (EnumMemberDeclaration enumMemberDeclaration)
		{
			StartNode (enumMemberDeclaration);
			WriteAttributes (enumMemberDeclaration.Attributes);
			WriteModifiers (enumMemberDeclaration.ModifierTokens);
			WriteIdentifier (enumMemberDeclaration.Name);
			if (!enumMemberDeclaration.Initializer.IsNull) {
				Space (policy.SpaceAroundAssignment);
				WriteToken (Roles.Assign);
				Space (policy.SpaceAroundAssignment);
				enumMemberDeclaration.Initializer.AcceptVisitor (this);
			}
			EndNode (enumMemberDeclaration);
		}
		
		public void VisitEventDeclaration (EventDeclaration eventDeclaration)
		{
			StartNode (eventDeclaration);
			WriteAttributes (eventDeclaration.Attributes);
			WriteModifiers (eventDeclaration.ModifierTokens);
			WriteKeyword (EventDeclaration.EventKeywordRole);
			eventDeclaration.ReturnType.AcceptVisitor (this);
			Space ();
			WriteCommaSeparatedList (eventDeclaration.Variables);
			Semicolon ();
			EndNode (eventDeclaration);
		}
		
		public void VisitCustomEventDeclaration (CustomEventDeclaration customEventDeclaration)
		{
			StartNode (customEventDeclaration);
			WriteAttributes (customEventDeclaration.Attributes);
			WriteModifiers (customEventDeclaration.ModifierTokens);
			WriteKeyword (CustomEventDeclaration.EventKeywordRole);
			customEventDeclaration.ReturnType.AcceptVisitor (this);
			Space ();
			WritePrivateImplementationType (customEventDeclaration.PrivateImplementationType);
			WriteIdentifier (customEventDeclaration.Name);
			OpenBrace (policy.EventBraceStyle);
			// output add/remove in their original order
			foreach (AstNode node in customEventDeclaration.Children) {
				if (node.Role == CustomEventDeclaration.AddAccessorRole || node.Role == CustomEventDeclaration.RemoveAccessorRole) {
					node.AcceptVisitor (this);
				}
			}
			CloseBrace (policy.EventBraceStyle);
			NewLine ();
			EndNode (customEventDeclaration);
		}
		
		public void VisitFieldDeclaration (FieldDeclaration fieldDeclaration)
		{
			StartNode (fieldDeclaration);
			WriteAttributes (fieldDeclaration.Attributes);
			WriteModifiers (fieldDeclaration.ModifierTokens);
			fieldDeclaration.ReturnType.AcceptVisitor (this);
			Space ();
			WriteCommaSeparatedList (fieldDeclaration.Variables);
			Semicolon ();
			EndNode (fieldDeclaration);
		}
		
		public void VisitFixedFieldDeclaration (FixedFieldDeclaration fixedFieldDeclaration)
		{
			StartNode (fixedFieldDeclaration);
			WriteAttributes (fixedFieldDeclaration.Attributes);
			WriteModifiers (fixedFieldDeclaration.ModifierTokens);
			WriteKeyword (FixedFieldDeclaration.FixedKeywordRole);
			Space ();
			fixedFieldDeclaration.ReturnType.AcceptVisitor (this);
			Space ();
			WriteCommaSeparatedList (fixedFieldDeclaration.Variables);
			Semicolon ();
			EndNode (fixedFieldDeclaration);
		}
		
		public void VisitFixedVariableInitializer (FixedVariableInitializer fixedVariableInitializer)
		{
			StartNode (fixedVariableInitializer);
			WriteIdentifier (fixedVariableInitializer.Name);
			if (!fixedVariableInitializer.CountExpression.IsNull) {
				WriteToken (Roles.LBracket);
				Space (policy.SpacesWithinBrackets);
				fixedVariableInitializer.CountExpression.AcceptVisitor (this);
				Space (policy.SpacesWithinBrackets);
				WriteToken (Roles.RBracket);
			}
			EndNode (fixedVariableInitializer);
		}
		
		public void VisitIndexerDeclaration (IndexerDeclaration indexerDeclaration)
		{
			StartNode (indexerDeclaration);
			WriteAttributes (indexerDeclaration.Attributes);
			WriteModifiers (indexerDeclaration.ModifierTokens);
			indexerDeclaration.ReturnType.AcceptVisitor (this);
			WritePrivateImplementationType (indexerDeclaration.PrivateImplementationType);
			WriteKeyword (IndexerDeclaration.ThisKeywordRole);
			Space (policy.SpaceBeforeMethodDeclarationParentheses);
			WriteCommaSeparatedListInBrackets (indexerDeclaration.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			OpenBrace (policy.PropertyBraceStyle);
			// output get/set in their original order
			foreach (AstNode node in indexerDeclaration.Children) {
				if (node.Role == IndexerDeclaration.GetterRole || node.Role == IndexerDeclaration.SetterRole) {
					node.AcceptVisitor (this);
				}
			}
			CloseBrace (policy.PropertyBraceStyle);
			NewLine ();
			EndNode (indexerDeclaration);
		}
		
		public void VisitMethodDeclaration (MethodDeclaration methodDeclaration)
		{
			StartNode (methodDeclaration);
			WriteAttributes (methodDeclaration.Attributes);
			WriteModifiers (methodDeclaration.ModifierTokens);
			methodDeclaration.ReturnType.AcceptVisitor (this);
			Space ();
			WritePrivateImplementationType (methodDeclaration.PrivateImplementationType);
			WriteIdentifier (methodDeclaration.Name);
			WriteTypeParameters (methodDeclaration.TypeParameters);
			Space (policy.SpaceBeforeMethodDeclarationParentheses);
			WriteCommaSeparatedListInParenthesis (methodDeclaration.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			foreach (Constraint constraint in methodDeclaration.Constraints) {
				constraint.AcceptVisitor (this);
			}
			WriteMethodBody (methodDeclaration.Body);
			EndNode (methodDeclaration);
		}
		
		public void VisitOperatorDeclaration (OperatorDeclaration operatorDeclaration)
		{
			StartNode (operatorDeclaration);
			WriteAttributes (operatorDeclaration.Attributes);
			WriteModifiers (operatorDeclaration.ModifierTokens);
			if (operatorDeclaration.OperatorType == OperatorType.Explicit) {
				WriteKeyword (OperatorDeclaration.ExplicitRole);
			} else if (operatorDeclaration.OperatorType == OperatorType.Implicit) {
				WriteKeyword (OperatorDeclaration.ImplicitRole);
			} else {
				operatorDeclaration.ReturnType.AcceptVisitor (this);
			}
			WriteKeyword (OperatorDeclaration.OperatorKeywordRole);
			Space ();
			if (operatorDeclaration.OperatorType == OperatorType.Explicit
			    || operatorDeclaration.OperatorType == OperatorType.Implicit) {
				operatorDeclaration.ReturnType.AcceptVisitor (this);
			} else {
				WriteToken (OperatorDeclaration.GetToken (operatorDeclaration.OperatorType), OperatorDeclaration.GetRole (operatorDeclaration.OperatorType));
			}
			Space (policy.SpaceBeforeMethodDeclarationParentheses);
			WriteCommaSeparatedListInParenthesis (operatorDeclaration.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			WriteMethodBody (operatorDeclaration.Body);
			EndNode (operatorDeclaration);
		}
		
		public void VisitParameterDeclaration (ParameterDeclaration parameterDeclaration)
		{
			StartNode (parameterDeclaration);
			WriteAttributes (parameterDeclaration.Attributes);
			switch (parameterDeclaration.ParameterModifier) {
				case ParameterModifier.Ref:
					WriteKeyword (ParameterDeclaration.RefModifierRole);
					break;
				case ParameterModifier.Out:
					WriteKeyword (ParameterDeclaration.OutModifierRole);
					break;
				case ParameterModifier.Params:
					WriteKeyword (ParameterDeclaration.ParamsModifierRole);
					break;
				case ParameterModifier.This:
					WriteKeyword (ParameterDeclaration.ThisModifierRole);
					break;
			}
			parameterDeclaration.Type.AcceptVisitor (this);
			if (!parameterDeclaration.Type.IsNull && !string.IsNullOrEmpty (parameterDeclaration.Name))
				Space ();
			if (!string.IsNullOrEmpty (parameterDeclaration.Name))
				WriteIdentifier (parameterDeclaration.Name);
			if (!parameterDeclaration.DefaultExpression.IsNull) {
				Space (policy.SpaceAroundAssignment);
				WriteToken (Roles.Assign);
				Space (policy.SpaceAroundAssignment);
				parameterDeclaration.DefaultExpression.AcceptVisitor (this);
			}
			EndNode (parameterDeclaration);
		}
		
		public void VisitPropertyDeclaration (PropertyDeclaration propertyDeclaration)
		{
			StartNode (propertyDeclaration);
			WriteAttributes (propertyDeclaration.Attributes);
			WriteModifiers (propertyDeclaration.ModifierTokens);
			propertyDeclaration.ReturnType.AcceptVisitor (this);
			Space ();
			WritePrivateImplementationType (propertyDeclaration.PrivateImplementationType);
			WriteIdentifier (propertyDeclaration.Name);
			OpenBrace (policy.PropertyBraceStyle);
			// output get/set in their original order
			foreach (AstNode node in propertyDeclaration.Children) {
				if (node.Role == IndexerDeclaration.GetterRole || node.Role == IndexerDeclaration.SetterRole) {
					node.AcceptVisitor (this);
				}
			}
			CloseBrace (policy.PropertyBraceStyle);
			NewLine ();
			EndNode (propertyDeclaration);
		}

		#endregion
		
		#region Other nodes
		public void VisitVariableInitializer (VariableInitializer variableInitializer)
		{
			StartNode (variableInitializer);
			WriteIdentifier (variableInitializer.Name);
			if (!variableInitializer.Initializer.IsNull) {
				Space (policy.SpaceAroundAssignment);
				WriteToken (Roles.Assign);
				Space (policy.SpaceAroundAssignment);
				variableInitializer.Initializer.AcceptVisitor (this);
			}
			EndNode (variableInitializer);
		}
		
		public void VisitCompilationUnit (CompilationUnit compilationUnit)
		{
			// don't do node tracking as we visit all children directly
			foreach (AstNode node in compilationUnit.Children)
				node.AcceptVisitor (this);
		}
		
		public void VisitSimpleType (SimpleType simpleType)
		{
			StartNode (simpleType);
			WriteIdentifier (simpleType.Identifier);
			WriteTypeArguments (simpleType.TypeArguments);
			EndNode (simpleType);
		}
		
		public void VisitMemberType (MemberType memberType)
		{
			StartNode (memberType);
			memberType.Target.AcceptVisitor (this);
			if (memberType.IsDoubleColon)
				WriteToken (Roles.DoubleColon);
			else
				WriteToken (Roles.Dot);
			WriteIdentifier (memberType.MemberName);
			WriteTypeArguments (memberType.TypeArguments);
			EndNode (memberType);
		}
		
		public void VisitComposedType (ComposedType composedType)
		{
			StartNode (composedType);
			composedType.BaseType.AcceptVisitor (this);
			if (composedType.HasNullableSpecifier)
				WriteToken (ComposedType.NullableRole);
			for (int i = 0; i < composedType.PointerRank; i++)
				WriteToken (ComposedType.PointerRole);
			foreach (var node in composedType.ArraySpecifiers)
				node.AcceptVisitor (this);
			EndNode (composedType);
		}
		
		public void VisitArraySpecifier (ArraySpecifier arraySpecifier)
		{
			StartNode (arraySpecifier);
			WriteToken (Roles.LBracket);
			foreach (var comma in arraySpecifier.GetChildrenByRole(Roles.Comma)) {
				WriteSpecialsUpToNode (comma);
				formatter.WriteToken (",");
				lastWritten = LastWritten.Other;
			}
			WriteToken (Roles.RBracket);
			EndNode (arraySpecifier);
		}
		
		public void VisitPrimitiveType (PrimitiveType primitiveType)
		{
			StartNode (primitiveType);
			WriteKeyword (primitiveType.Keyword);
			if (primitiveType.Keyword == "new") {
				// new() constraint
				LPar ();
				RPar ();
			}
			EndNode (primitiveType);
		}
		
		public void VisitComment (Comment comment)
		{
			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.StartNode(comment);
			formatter.WriteComment (comment.CommentType, comment.Content);
			formatter.EndNode(comment);
			lastWritten = LastWritten.Whitespace;
		}
		
		public void VisitPreProcessorDirective (PreProcessorDirective preProcessorDirective)
		{
			formatter.StartNode (preProcessorDirective);
			formatter.WritePreProcessorDirective(preProcessorDirective.Type, preProcessorDirective.Argument);
			formatter.EndNode (preProcessorDirective);
			lastWritten = LastWritten.Whitespace;
		}
		
		public void VisitTypeParameterDeclaration (TypeParameterDeclaration typeParameterDeclaration)
		{
			StartNode (typeParameterDeclaration);
			WriteAttributes (typeParameterDeclaration.Attributes);
			switch (typeParameterDeclaration.Variance) {
				case VarianceModifier.Invariant:
					break;
				case VarianceModifier.Covariant:
					WriteKeyword (TypeParameterDeclaration.OutVarianceKeywordRole);
					break;
				case VarianceModifier.Contravariant:
					WriteKeyword (TypeParameterDeclaration.InVarianceKeywordRole);
					break;
				default:
					throw new NotSupportedException ("Invalid value for VarianceModifier");
			}
			WriteIdentifier (typeParameterDeclaration.Name);
			EndNode (typeParameterDeclaration);
		}
		
		public void VisitConstraint(Constraint constraint)
		{
			StartNode(constraint);
			Space();
			WriteKeyword(Roles.WhereKeyword);
			WriteIdentifier(constraint.TypeParameter.Identifier);
			Space();
			WriteToken(Roles.Colon);
			Space ();
			WriteCommaSeparatedList (constraint.BaseTypes);
			EndNode (constraint);
		}
		
		public void VisitCSharpTokenNode (CSharpTokenNode cSharpTokenNode)
		{
			CSharpModifierToken mod = cSharpTokenNode as CSharpModifierToken;
			if (mod != null) {
				StartNode (mod);
				WriteKeyword (CSharpModifierToken.GetModifierName (mod.Modifier));
				EndNode (mod);
			} else {
				throw new NotSupportedException ("Should never visit individual tokens");
			}
		}
		
		public void VisitIdentifier (Identifier identifier)
		{
			StartNode (identifier);
			WriteIdentifier (identifier.Name);
			EndNode (identifier);
		}

		#endregion
		
		#region Pattern Nodes
		public void VisitPatternPlaceholder (AstNode placeholder, PatternMatching.Pattern pattern)
		{
			StartNode (placeholder);
			VisitNodeInPattern(pattern);
			EndNode (placeholder);
		}
		
		void VisitAnyNode (AnyNode anyNode)
		{
			if (!string.IsNullOrEmpty (anyNode.GroupName)) {
				WriteIdentifier (anyNode.GroupName);
				WriteToken (Roles.Colon);
			}
		}
		
		void VisitBackreference (Backreference backreference)
		{
			WriteKeyword ("backreference");
			LPar ();
			WriteIdentifier (backreference.ReferencedGroupName);
			RPar ();
		}
		
		void VisitIdentifierExpressionBackreference (IdentifierExpressionBackreference identifierExpressionBackreference)
		{
			WriteKeyword ("identifierBackreference");
			LPar ();
			WriteIdentifier (identifierExpressionBackreference.ReferencedGroupName);
			RPar ();
		}
		
		void VisitChoice (Choice choice)
		{
			WriteKeyword ("choice");
			Space ();
			LPar ();
			NewLine ();
			formatter.Indent ();
			foreach (INode alternative in choice) {
				VisitNodeInPattern (alternative);
				if (alternative != choice.Last ())
					WriteToken (Roles.Comma);
				NewLine ();
			}
			formatter.Unindent ();
			RPar ();
		}
		
		void VisitNamedNode (NamedNode namedNode)
		{
			if (!string.IsNullOrEmpty (namedNode.GroupName)) {
				WriteIdentifier (namedNode.GroupName);
				WriteToken (Roles.Colon);
			}
			VisitNodeInPattern (namedNode.ChildNode);
		}
		
		void VisitRepeat (Repeat repeat)
		{
			WriteKeyword ("repeat");
			LPar ();
			if (repeat.MinCount != 0 || repeat.MaxCount != int.MaxValue) {
				WriteIdentifier (repeat.MinCount.ToString ());
				WriteToken (Roles.Comma);
				WriteIdentifier (repeat.MaxCount.ToString ());
				WriteToken (Roles.Comma);
			}
			VisitNodeInPattern (repeat.ChildNode);
			RPar ();
		}
		
		void VisitOptionalNode (OptionalNode optionalNode)
		{
			WriteKeyword ("optional");
			LPar ();
			VisitNodeInPattern (optionalNode.ChildNode);
			RPar ();
		}
		
		void VisitNodeInPattern (INode childNode)
		{
			if (childNode is AstNode) {
				((AstNode)childNode).AcceptVisitor (this);
			} else if (childNode is IdentifierExpressionBackreference) {
				VisitIdentifierExpressionBackreference((IdentifierExpressionBackreference)childNode);
			} else if (childNode is Choice) {
				VisitChoice((Choice)childNode);
			} else if (childNode is AnyNode) {
				VisitAnyNode((AnyNode)childNode);
			} else if (childNode is Backreference) {
				VisitBackreference((Backreference)childNode);
			} else if (childNode is NamedNode) {
				VisitNamedNode((NamedNode)childNode);
			} else if (childNode is OptionalNode) {
				VisitOptionalNode((OptionalNode)childNode);
			} else if (childNode is Repeat) {
				VisitRepeat((Repeat)childNode);
			} else {
				WritePrimitiveValue(childNode);
			}
		}
		#endregion
		
		#region Documentation Reference
		public void VisitDocumentationReference (DocumentationReference documentationReference)
		{
			StartNode(documentationReference);
			if (!documentationReference.DeclaringType.IsNull) {
				documentationReference.DeclaringType.AcceptVisitor (this);
				if (documentationReference.EntityType != EntityType.TypeDefinition)
					WriteToken(Roles.Dot);
			}
			switch (documentationReference.EntityType) {
				case EntityType.TypeDefinition:
					// we already printed the DeclaringType
					break;
				case EntityType.Indexer:
					WriteKeyword(IndexerDeclaration.ThisKeywordRole);
					break;
				case EntityType.Operator:
					var opType = documentationReference.OperatorType;
					if (opType == OperatorType.Explicit) {
						WriteKeyword (OperatorDeclaration.ExplicitRole);
					} else if (opType == OperatorType.Implicit) {
						WriteKeyword (OperatorDeclaration.ImplicitRole);
					}
					WriteKeyword (OperatorDeclaration.OperatorKeywordRole);
					Space ();
					if (opType == OperatorType.Explicit || opType == OperatorType.Implicit) {
						documentationReference.ConversionOperatorReturnType.AcceptVisitor (this);
					} else {
						WriteToken (OperatorDeclaration.GetToken (opType), OperatorDeclaration.GetRole (opType));
					}
					break;
				default:
					WriteIdentifier(documentationReference.MemberName);
					break;
			}
			WriteTypeArguments(documentationReference.TypeArguments);
			if (documentationReference.HasParameterList) {
				Space(policy.SpaceBeforeMethodDeclarationParentheses);
				if (documentationReference.EntityType == EntityType.Indexer)
					WriteCommaSeparatedListInBrackets(documentationReference.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
				else
					WriteCommaSeparatedListInParenthesis(documentationReference.Parameters, policy.SpaceWithinMethodDeclarationParentheses);
			}
			EndNode(documentationReference);
		}
		#endregion
	}
}