// Copyright (c) 2010-2013 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.Linq;
using System.Text;
using System.Threading;
using ICSharpCode.NRefactory.CSharp.Analysis;
using ICSharpCode.NRefactory.CSharp.TypeSystem;
using ICSharpCode.NRefactory.Semantics;
using ICSharpCode.NRefactory.TypeSystem;
using ICSharpCode.NRefactory.TypeSystem.Implementation;

namespace ICSharpCode.NRefactory.CSharp.Resolver
{
	/// <summary>
	/// Traverses the DOM and resolves expressions.
	/// </summary>
	/// <remarks>
	/// The ResolveVisitor does two jobs at the same time: it tracks the resolve context (properties on CSharpResolver)
	/// and it resolves the expressions visited.
	/// To allow using the context tracking without having to resolve every expression in the file (e.g. when you want to resolve
	/// only a single node deep within the DOM), you can use the <see cref="IResolveVisitorNavigator"/> interface.
	/// The navigator allows you to switch the between scanning mode and resolving mode.
	/// In scanning mode, the context is tracked (local variables registered etc.), but nodes are not resolved.
	/// While scanning, the navigator will get asked about every node that the resolve visitor is about to enter.
	/// This allows the navigator whether to keep scanning, whether switch to resolving mode, or whether to completely skip the
	/// subtree rooted at that node.
	/// 
	/// In resolving mode, the context is tracked and nodes will be resolved.
	/// The resolve visitor may decide that it needs to resolve other nodes as well in order to resolve the current node.
	/// In this case, those nodes will be resolved automatically, without asking the navigator interface.
	/// For child nodes that are not essential to resolving, the resolve visitor will switch back to scanning mode (and thus will
	/// ask the navigator for further instructions).
	/// 
	/// Moreover, there is the <c>ResolveAll</c> mode - it works similar to resolving mode, but will not switch back to scanning mode.
	/// The whole subtree will be resolved without notifying the navigator.
	/// </remarks>
	sealed class ResolveVisitor : IAstVisitor<ResolveResult>
	{
		// The ResolveVisitor is also responsible for handling lambda expressions.
		
		static readonly ResolveResult errorResult = ErrorResolveResult.UnknownError;
		
		CSharpResolver resolver;
		/// <summary>Resolve result of the current LINQ query.</summary>
		/// <remarks>We do not have to put this into the stored state (resolver) because
		/// query expressions are always resolved in a single operation.</remarks>
		ResolveResult currentQueryResult;
		readonly CSharpUnresolvedFile unresolvedFile;
		readonly Dictionary<AstNode, ResolveResult> resolveResultCache = new Dictionary<AstNode, ResolveResult>();
		readonly Dictionary<AstNode, CSharpResolver> resolverBeforeDict = new Dictionary<AstNode, CSharpResolver>();
		readonly Dictionary<AstNode, CSharpResolver> resolverAfterDict = new Dictionary<AstNode, CSharpResolver>();
		readonly Dictionary<Expression, ConversionWithTargetType> conversionDict = new Dictionary<Expression, ConversionWithTargetType>();
		
		internal struct ConversionWithTargetType
		{
			public readonly Conversion Conversion;
			public readonly IType TargetType;
			
			public ConversionWithTargetType(Conversion conversion, IType targetType)
			{
				this.Conversion = conversion;
				this.TargetType = targetType;
			}
		}
		
		IResolveVisitorNavigator navigator;
		bool resolverEnabled;
		List<LambdaBase> undecidedLambdas;
		internal CancellationToken cancellationToken;
		
		#region Constructor
		static readonly IResolveVisitorNavigator skipAllNavigator = new ConstantModeResolveVisitorNavigator(ResolveVisitorNavigationMode.Skip, null);
		
		/// <summary>
		/// Creates a new ResolveVisitor instance.
		/// </summary>
		public ResolveVisitor(CSharpResolver resolver, CSharpUnresolvedFile unresolvedFile)
		{
			if (resolver == null)
				throw new ArgumentNullException("resolver");
			this.resolver = resolver;
			this.unresolvedFile = unresolvedFile;
			this.navigator = skipAllNavigator;
		}
		
		internal void SetNavigator(IResolveVisitorNavigator navigator)
		{
			this.navigator = navigator ?? skipAllNavigator;
		}
		
		ResolveResult voidResult {
			get {
				return new ResolveResult(resolver.Compilation.FindType(KnownTypeCode.Void));
			}
		}
		#endregion
		
		#region ResetContext
		/// <summary>
		/// Resets the visitor to the stored position, runs the action, and then reverts the visitor to the previous position.
		/// </summary>
		void ResetContext(CSharpResolver storedContext, Action action)
		{
			var oldResolverEnabled = this.resolverEnabled;
			var oldResolver = this.resolver;
			var oldQueryResult = this.currentQueryResult;
			try {
				this.resolverEnabled = false;
				this.resolver = storedContext;
				this.currentQueryResult = null;
				
				action();
			} finally {
				this.resolverEnabled = oldResolverEnabled;
				this.resolver = oldResolver;
				this.currentQueryResult = oldQueryResult;
			}
		}
		#endregion
		
		#region Scan / Resolve
		/// <summary>
		/// Scans the AST rooted at the given node.
		/// </summary>
		public void Scan(AstNode node)
		{
			if (node == null || node.IsNull)
				return;
			switch (node.NodeType) {
				case NodeType.Token:
				case NodeType.Whitespace:
					return; // skip tokens, identifiers, comments, etc.
			}
			// don't Scan again if the node was already resolved
			if (resolveResultCache.ContainsKey(node)) {
				// Restore state change caused by this node:
				CSharpResolver newResolver;
				if (resolverAfterDict.TryGetValue(node, out newResolver))
					resolver = newResolver;
				return;
			}
			
			var mode = navigator.Scan(node);
			switch (mode) {
				case ResolveVisitorNavigationMode.Skip:
					if (node is VariableDeclarationStatement || node is SwitchSection) {
						// Enforce scanning of variable declarations.
						goto case ResolveVisitorNavigationMode.Scan;
					}
					StoreCurrentState(node);
					break;
				case ResolveVisitorNavigationMode.Scan:
					bool oldResolverEnabled = resolverEnabled;
					var oldResolver = resolver;
					resolverEnabled = false;
					StoreCurrentState(node);
					ResolveResult result = node.AcceptVisitor(this);
					if (result != null) {
						// If the node was resolved, store the result even though it wasn't requested.
						// This is necessary so that Visit-methods that decide to always resolve are
						// guaranteed to get called only once.
						// This is used for lambda registration.
						StoreResult(node, result);
						if (resolver != oldResolver) {
							// The node changed the resolver state:
							resolverAfterDict.Add(node, resolver);
						}
						cancellationToken.ThrowIfCancellationRequested();
					}
					resolverEnabled = oldResolverEnabled;
					break;
				case ResolveVisitorNavigationMode.Resolve:
					Resolve(node);
					break;
				default:
					throw new InvalidOperationException("Invalid value for ResolveVisitorNavigationMode");
			}
		}
		
		/// <summary>
		/// Equivalent to 'Scan', but also resolves the node at the same time.
		/// This method should be only used if the CSharpResolver passed to the ResolveVisitor was manually set
		/// to the correct state.
		/// Otherwise, use <c>resolver.Scan(syntaxTree); var result = resolver.GetResolveResult(node);</c>
		/// instead.
		/// --
		/// This method now is internal, because it is difficult to use correctly.
		/// Users of the public API should use Scan()+GetResolveResult() instead.
		/// </summary>
		internal ResolveResult Resolve(AstNode node)
		{
			if (node == null || node.IsNull)
				return errorResult;
			bool oldResolverEnabled = resolverEnabled;
			resolverEnabled = true;
			ResolveResult result;
			if (!resolveResultCache.TryGetValue(node, out result)) {
				cancellationToken.ThrowIfCancellationRequested();
				StoreCurrentState(node);
				var oldResolver = resolver;
				result = node.AcceptVisitor(this) ?? errorResult;
				StoreResult(node, result);
				if (resolver != oldResolver) {
					// The node changed the resolver state:
					resolverAfterDict.Add(node, resolver);
				}
			}
			resolverEnabled = oldResolverEnabled;
			return result;
		}
		
		IType ResolveType(AstType type)
		{
			return Resolve(type).Type;
		}
		
		void StoreCurrentState(AstNode node)
		{
			// It's possible that we re-visit an expression that we scanned over earlier,
			// so we might have to overwrite an existing state.
			
			#if DEBUG
			CSharpResolver oldResolver;
			if (resolverBeforeDict.TryGetValue(node, out oldResolver)) {
				Debug.Assert(oldResolver.LocalVariables.SequenceEqual(resolver.LocalVariables));
			}
			#endif
			
			resolverBeforeDict[node] = resolver;
		}
		
		void StoreResult(AstNode node, ResolveResult result)
		{
			Debug.Assert(result != null);
			if (node.IsNull)
				return;
			Log.WriteLine("Resolved '{0}' to {1}", node, result);
			Debug.Assert(!CSharpAstResolver.IsUnresolvableNode(node));
			// The state should be stored before the result is.
			Debug.Assert(resolverBeforeDict.ContainsKey(node));
			// Don't store results twice.
			Debug.Assert(!resolveResultCache.ContainsKey(node));
			// Don't use ConversionResolveResult as a result, because it can get
			// confused with an implicit conversion.
			Debug.Assert(!(result is ConversionResolveResult) || result is CastResolveResult);
			resolveResultCache[node] = result;
			if (navigator != null)
				navigator.Resolved(node, result);
		}
		
		void ScanChildren(AstNode node)
		{
			for (AstNode child = node.FirstChild; child != null; child = child.NextSibling) {
				Scan(child);
			}
		}
		#endregion
		
		#region Process Conversions
		sealed class AnonymousFunctionConversion : Conversion
		{
			public readonly IType ReturnType;
			public readonly ExplicitlyTypedLambda ExplicitlyTypedLambda;
			public readonly LambdaTypeHypothesis Hypothesis;
			readonly bool isValid;
			
			public AnonymousFunctionConversion(IType returnType, LambdaTypeHypothesis hypothesis, bool isValid)
			{
				if (returnType == null)
					throw new ArgumentNullException("returnType");
				this.ReturnType = returnType;
				this.Hypothesis = hypothesis;
				this.isValid = isValid;
			}
			
			public AnonymousFunctionConversion(IType returnType, ExplicitlyTypedLambda explicitlyTypedLambda, bool isValid)
			{
				if (returnType == null)
					throw new ArgumentNullException("returnType");
				this.ReturnType = returnType;
				this.ExplicitlyTypedLambda = explicitlyTypedLambda;
				this.isValid = isValid;
			}
			
			public override bool IsValid {
				get { return isValid; }
			}
			
			public override bool IsImplicit {
				get { return true; }
			}
			
			public override bool IsAnonymousFunctionConversion {
				get { return true; }
			}
		}
		
		/// <summary>
		/// Convert 'rr' to the target type using the specified conversion.
		/// </summary>
		void ProcessConversion(Expression expr, ResolveResult rr, Conversion conversion, IType targetType)
		{
			AnonymousFunctionConversion afc = conversion as AnonymousFunctionConversion;
			if (afc != null) {
				Log.WriteLine("Processing conversion of anonymous function to " + targetType + "...");
				
				Log.Indent();
				if (afc.Hypothesis != null)
					afc.Hypothesis.MergeInto(this, afc.ReturnType);
				if (afc.ExplicitlyTypedLambda != null)
					afc.ExplicitlyTypedLambda.ApplyReturnType(this, afc.ReturnType);
				Log.Unindent();
			}
			if (expr != null && !expr.IsNull && conversion != Conversion.IdentityConversion) {
				navigator.ProcessConversion(expr, rr, conversion, targetType);
				conversionDict[expr] = new ConversionWithTargetType(conversion, targetType);
			}
		}
		
		void ImportConversions(ResolveVisitor childVisitor)
		{
			foreach (var pair in childVisitor.conversionDict) {
				conversionDict.Add(pair.Key, pair.Value);
				navigator.ProcessConversion(pair.Key, resolveResultCache[pair.Key], pair.Value.Conversion, pair.Value.TargetType);
			}
		}
		
		/// <summary>
		/// Convert 'rr' to the target type.
		/// </summary>
		void ProcessConversion(Expression expr, ResolveResult rr, IType targetType)
		{
			if (expr == null || expr.IsNull)
				return;
			ProcessConversion(expr, rr, resolver.conversions.ImplicitConversion(rr, targetType), targetType);
		}
		
		/// <summary>
		/// Resolves the specified expression and processes the conversion to targetType.
		/// </summary>
		void ResolveAndProcessConversion(Expression expr, IType targetType)
		{
			if (targetType.Kind == TypeKind.Unknown) {
				// no need to resolve the expression right now
				Scan(expr);
			} else {
				ProcessConversion(expr, Resolve(expr), targetType);
			}
		}
		
		void ProcessConversionResult(Expression expr, ConversionResolveResult rr)
		{
			if (rr != null && !(rr is CastResolveResult))
				ProcessConversion(expr, rr.Input, rr.Conversion, rr.Type);
		}
		
		void ProcessConversionResults(IEnumerable<Expression> expr, IEnumerable<ResolveResult> conversionResolveResults)
		{
			Debug.Assert(expr.Count() == conversionResolveResults.Count());
			using (var e1 = expr.GetEnumerator()) {
				using (var e2 = conversionResolveResults.GetEnumerator()) {
					while (e1.MoveNext() && e2.MoveNext()) {
						ProcessConversionResult(e1.Current, e2.Current as ConversionResolveResult);
					}
				}
			}
		}
		
		void MarkUnknownNamedArguments(IEnumerable<Expression> arguments)
		{
			foreach (var nae in arguments.OfType<NamedArgumentExpression>()) {
				StoreCurrentState(nae);
				StoreResult(nae, new NamedArgumentResolveResult(nae.Name, resolveResultCache[nae.Expression]));
			}
		}
		
		void ProcessInvocationResult(Expression target, IEnumerable<Expression> arguments, ResolveResult invocation)
		{
			if (invocation is CSharpInvocationResolveResult || invocation is DynamicInvocationResolveResult) {
				int i = 0;
				IList<ResolveResult> argumentsRR;
				if (invocation is CSharpInvocationResolveResult) {
					var csi = (CSharpInvocationResolveResult)invocation;
					if (csi.IsExtensionMethodInvocation) {
						Debug.Assert(arguments.Count() + 1 == csi.Arguments.Count);
						ProcessConversionResult(target, csi.Arguments[0] as ConversionResolveResult);
						i = 1;
					} else {
						Debug.Assert(arguments.Count() == csi.Arguments.Count);
					}
					argumentsRR = csi.Arguments;
				}
				else {
					argumentsRR = ((DynamicInvocationResolveResult)invocation).Arguments;
				}

				foreach (Expression arg in arguments) {
					ResolveResult argRR = argumentsRR[i++];
					NamedArgumentExpression nae = arg as NamedArgumentExpression;
					NamedArgumentResolveResult nrr = argRR as NamedArgumentResolveResult;
					Debug.Assert((nae == null) == (nrr == null));
					if (nae != null && nrr != null) {
						StoreCurrentState(nae);
						StoreResult(nae, nrr);
						ProcessConversionResult(nae.Expression, nrr.Argument as ConversionResolveResult);
					} else {
						ProcessConversionResult(arg, argRR as ConversionResolveResult);
					}
				}
			}
			else {
				MarkUnknownNamedArguments(arguments);
			}
		}
		#endregion
		
		#region GetResolveResult
		/// <summary>
		/// Gets the resolve result for the specified node.
		/// If the node was not resolved by the navigator, this method will resolve it.
		/// </summary>
		public ResolveResult GetResolveResult(AstNode node)
		{
			Debug.Assert(!CSharpAstResolver.IsUnresolvableNode(node));
			
			MergeUndecidedLambdas();
			ResolveResult result;
			if (resolveResultCache.TryGetValue(node, out result))
				return result;
			
			AstNode parent;
			CSharpResolver storedResolver = GetPreviouslyScannedContext(node, out parent);
			ResetContext(
				storedResolver,
				delegate {
					navigator = new NodeListResolveVisitorNavigator(node);
					Debug.Assert(!resolverEnabled);
					Scan(parent);
					navigator = skipAllNavigator;
				});
			
			MergeUndecidedLambdas();
			return resolveResultCache[node];
		}
		
		CSharpResolver GetPreviouslyScannedContext(AstNode node, out AstNode parent)
		{
			parent = node;
			CSharpResolver storedResolver;
			while (!resolverBeforeDict.TryGetValue(parent, out storedResolver)) {
				AstNode tmp = parent.Parent;
				if (tmp == null)
					throw new InvalidOperationException("Could not find a resolver state for any parent of the specified node. Are you trying to resolve a node that is not a descendant of the CSharpAstResolver's root node?");
				if (tmp.NodeType == NodeType.Whitespace)
					return resolver; // special case: resolve expression within preprocessor directive
				parent = tmp;
			}
			return storedResolver;
		}
		
		/// <summary>
		/// Gets the resolver state in front of the specified node.
		/// If the node was not visited by a previous scanning process, the
		/// AST will be scanned again to determine the state.
		/// </summary>
		public CSharpResolver GetResolverStateBefore(AstNode node)
		{
			MergeUndecidedLambdas();
			CSharpResolver r;
			if (resolverBeforeDict.TryGetValue(node, out r))
				return r;
			
			AstNode parent;
			CSharpResolver storedResolver = GetPreviouslyScannedContext(node, out parent);
			ResetContext(
				storedResolver,
				delegate {
					navigator = new NodeListResolveVisitorNavigator(new[] { node }, scanOnly: true);
					Debug.Assert(!resolverEnabled);
					// parent might already be resolved if 'node' is an unresolvable node
					Scan(parent);
					navigator = skipAllNavigator;
				});
			
			MergeUndecidedLambdas();
			while (node != null) {
				if (resolverBeforeDict.TryGetValue(node, out r))
					return r;
				node = node.Parent;
			}
			return null;
		}
		
		public CSharpResolver GetResolverStateAfter(AstNode node)
		{
			// Resolve the node to fill the resolverAfterDict
			GetResolveResult(node);
			CSharpResolver result;
			if (resolverAfterDict.TryGetValue(node, out result))
				return result;
			else
				return GetResolverStateBefore(node);
		}
		
		public ConversionWithTargetType GetConversionWithTargetType(Expression expr)
		{
			GetResolverStateBefore(expr);
			ResolveParentForConversion(expr);
			ConversionWithTargetType result;
			if (conversionDict.TryGetValue(expr, out result)) {
				return result;
			} else {
				ResolveResult rr = GetResolveResult(expr);
				return new ConversionWithTargetType(Conversion.IdentityConversion, rr.Type);
			}
		}
		#endregion
		
		#region Track UsingScope
		ResolveResult IAstVisitor<ResolveResult>.VisitSyntaxTree(SyntaxTree unit)
		{
			CSharpResolver previousResolver = resolver;
			try {
				if (unresolvedFile != null) {
					resolver = resolver.WithCurrentUsingScope(unresolvedFile.RootUsingScope.Resolve(resolver.Compilation));
				} else {
					var cv = new TypeSystemConvertVisitor(unit.FileName ?? string.Empty);
					ApplyVisitorToUsings(cv, unit.Children);
					PushUsingScope(cv.UnresolvedFile.RootUsingScope);
				}
				ScanChildren(unit);
				return voidResult;
			} finally {
				resolver = previousResolver;
			}
		}
		
		void ApplyVisitorToUsings(TypeSystemConvertVisitor visitor, IEnumerable<AstNode> children)
		{
			foreach (var child in children) {
				if (child is ExternAliasDeclaration || child is UsingDeclaration || child is UsingAliasDeclaration) {
					child.AcceptVisitor(visitor);
				}
			}
		}
		
		void PushUsingScope(UsingScope usingScope)
		{
			usingScope.Freeze();
			resolver = resolver.WithCurrentUsingScope(new ResolvedUsingScope(resolver.CurrentTypeResolveContext, usingScope));
		}

		ResolveResult IAstVisitor<ResolveResult>.VisitNamespaceDeclaration(NamespaceDeclaration namespaceDeclaration)
		{
			CSharpResolver previousResolver = resolver;
			try {
				var nsName = namespaceDeclaration.NamespaceName;
				AstNode child = namespaceDeclaration.FirstChild;

				for (; child != null && child.Role != Roles.LBrace; child = child.NextSibling) {
					Scan(child);
				}

				if (unresolvedFile != null) {
					resolver = resolver.WithCurrentUsingScope(unresolvedFile.GetUsingScope(namespaceDeclaration.StartLocation).Resolve(resolver.Compilation));

				} else {
//					string fileName = namespaceDeclaration.GetRegion().FileName ?? string.Empty;
					// Fetch parent using scope
					// Create root using scope if necessary
					if (resolver.CurrentUsingScope == null)
						PushUsingScope(new UsingScope());
					
					// Create child using scope
					DomRegion region = namespaceDeclaration.GetRegion();
					var identifiers = namespaceDeclaration.Identifiers.ToList();
					// For all but the last identifier:
					UsingScope usingScope;
					for (int i = 0; i < identifiers.Count - 1; i++) {
						usingScope = new UsingScope(resolver.CurrentUsingScope.UnresolvedUsingScope, identifiers[i]);
						usingScope.Region = region;
						PushUsingScope(usingScope);
					}
					// Last using scope:
					usingScope = new UsingScope(resolver.CurrentUsingScope.UnresolvedUsingScope, identifiers.Last());
					usingScope.Region = region;
					var cv = new TypeSystemConvertVisitor(new CSharpUnresolvedFile(), usingScope);
					ApplyVisitorToUsings(cv, namespaceDeclaration.Children);
					PushUsingScope(usingScope);
				}
				for (; child != null; child = child.NextSibling) {
					Scan(child);
				}

				// merge undecided lambdas before leaving the using scope so that
				// the resolver can make better use of its cache
				MergeUndecidedLambdas();
				if (resolver.CurrentUsingScope != null && resolver.CurrentUsingScope.Namespace != null)
					return new NamespaceResolveResult(resolver.CurrentUsingScope.Namespace);
				else
					return null;
			} finally {
				resolver = previousResolver;
			}
		}
		#endregion
		
		#region Track CurrentTypeDefinition
		ResolveResult VisitTypeOrDelegate(AstNode typeDeclaration, string name, int typeParameterCount)
		{
			CSharpResolver previousResolver = resolver;
			try {
				ITypeDefinition newTypeDefinition = null;
				if (resolver.CurrentTypeDefinition != null) {
					int totalTypeParameterCount = resolver.CurrentTypeDefinition.TypeParameterCount + typeParameterCount;
					foreach (ITypeDefinition nestedType in resolver.CurrentTypeDefinition.NestedTypes) {
						if (nestedType.Name == name && nestedType.TypeParameterCount == totalTypeParameterCount) {
							newTypeDefinition = nestedType;
							break;
						}
					}
				} else if (resolver.CurrentUsingScope != null) {
					newTypeDefinition = resolver.CurrentUsingScope.Namespace.GetTypeDefinition(name, typeParameterCount);
				}
				if (newTypeDefinition != null)
					resolver = resolver.WithCurrentTypeDefinition(newTypeDefinition);
				
				ScanChildren(typeDeclaration);
				
				// merge undecided lambdas before leaving the type definition so that
				// the resolver can make better use of its cache
				MergeUndecidedLambdas();
				
				return newTypeDefinition != null ? new TypeResolveResult(newTypeDefinition) : errorResult;
			} finally {
				resolver = previousResolver;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitTypeDeclaration(TypeDeclaration typeDeclaration)
		{
			return VisitTypeOrDelegate(typeDeclaration, typeDeclaration.Name, typeDeclaration.TypeParameters.Count);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitDelegateDeclaration(DelegateDeclaration delegateDeclaration)
		{
			return VisitTypeOrDelegate(delegateDeclaration, delegateDeclaration.Name, delegateDeclaration.TypeParameters.Count);
		}
		#endregion
		
		#region Track CurrentMember
		ResolveResult IAstVisitor<ResolveResult>.VisitFieldDeclaration(FieldDeclaration fieldDeclaration)
		{
			return VisitFieldOrEventDeclaration(fieldDeclaration, SymbolKind.Field);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitFixedFieldDeclaration(FixedFieldDeclaration fixedFieldDeclaration)
		{
			return VisitFieldOrEventDeclaration(fixedFieldDeclaration, SymbolKind.Field);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitEventDeclaration(EventDeclaration eventDeclaration)
		{
			return VisitFieldOrEventDeclaration(eventDeclaration, SymbolKind.Event);
		}
		
		ResolveResult VisitFieldOrEventDeclaration(EntityDeclaration fieldOrEventDeclaration, SymbolKind symbolKind)
		{
			//int initializerCount = fieldOrEventDeclaration.GetChildrenByRole(Roles.Variable).Count;
			CSharpResolver oldResolver = resolver;
			for (AstNode node = fieldOrEventDeclaration.FirstChild; node != null; node = node.NextSibling) {
				if (node.Role == Roles.Variable || node.Role == FixedFieldDeclaration.VariableRole) {
					IMember member;
					if (unresolvedFile != null) {
						member = GetMemberFromLocation(node);
					} else {
						string name = ((VariableInitializer)node).Name;
						member = AbstractUnresolvedMember.Resolve(resolver.CurrentTypeResolveContext, symbolKind, name);
					}
					resolver = resolver.WithCurrentMember(member);
					
					Scan(node);
					
					resolver = oldResolver;
				} else {
					Scan(node);
				}
			}
			return voidResult;
		}
		
		IMember GetMemberFromLocation(AstNode node)
		{
			ITypeDefinition typeDef = resolver.CurrentTypeDefinition;
			if (typeDef == null)
				return null;
			TextLocation location = TypeSystemConvertVisitor.GetStartLocationAfterAttributes(node);
			return typeDef.GetMembers(
				delegate (IUnresolvedMember m) {
					if (m.UnresolvedFile != unresolvedFile)
						return false;
					DomRegion region = m.Region;
					return !region.IsEmpty && region.Begin <= location && region.End > location;
				},
				GetMemberOptions.IgnoreInheritedMembers | GetMemberOptions.ReturnMemberDefinitions
			).FirstOrDefault();
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitVariableInitializer(VariableInitializer variableInitializer)
		{
			// Within the variable initializer, the newly declared variable is not yet available:
			var resolverWithVariable = resolver;
			if (variableInitializer.Parent is VariableDeclarationStatement)
				resolver = resolver.PopLastVariable();
			
			ArrayInitializerExpression aie = variableInitializer.Initializer as ArrayInitializerExpression;
			if (resolverEnabled || aie != null) {
				ResolveResult result = errorResult;
				if (variableInitializer.Parent is FieldDeclaration || variableInitializer.Parent is EventDeclaration) {
					if (resolver.CurrentMember != null) {
						result = new MemberResolveResult(null, resolver.CurrentMember, false);
					}
				} else {
					string identifier = variableInitializer.Name;
					foreach (IVariable v in resolverWithVariable.LocalVariables) {
						if (v.Name == identifier) {
							result = new LocalResolveResult(v);
							break;
						}
					}
				}
				ArrayType arrayType = result.Type as ArrayType;
				if (aie != null && arrayType != null) {
					StoreCurrentState(aie);
					List<Expression> initializerElements = new List<Expression>();
					int[] sizes = new int[arrayType.Dimensions];
					UnpackArrayInitializer(initializerElements, sizes, aie, 0, true);
					ResolveResult[] initializerElementResults = new ResolveResult[initializerElements.Count];
					for (int i = 0; i < initializerElementResults.Length; i++) {
						initializerElementResults[i] = Resolve(initializerElements[i]);
					}
					var arrayCreation = resolver.ResolveArrayCreation(arrayType.ElementType, sizes, initializerElementResults);
					StoreResult(aie, arrayCreation);
					ProcessConversionResults(initializerElements, arrayCreation.InitializerElements);
				} else if (variableInitializer.Parent is FixedStatement) {
					var initRR = Resolve(variableInitializer.Initializer);
					PointerType pointerType;
					if (initRR.Type.Kind == TypeKind.Array) {
						pointerType = new PointerType(((ArrayType)initRR.Type).ElementType);
					} else if (ReflectionHelper.GetTypeCode(initRR.Type) == TypeCode.String) {
						pointerType = new PointerType(resolver.Compilation.FindType(KnownTypeCode.Char));
					} else {
						pointerType = null;
						ProcessConversion(variableInitializer.Initializer, initRR, result.Type);
					}
					if (pointerType != null) {
						var conversion = resolver.conversions.ImplicitConversion(pointerType, result.Type);
						if (conversion.IsIdentityConversion)
							conversion = Conversion.ImplicitPointerConversion;
						ProcessConversion(variableInitializer.Initializer, initRR, conversion, result.Type);
					}
				} else {
					ResolveAndProcessConversion(variableInitializer.Initializer, result.Type);
				}
				resolver = resolverWithVariable;
				return result;
			} else {
				Scan(variableInitializer.Initializer);
				resolver = resolverWithVariable;
				return null;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitFixedVariableInitializer(FixedVariableInitializer fixedVariableInitializer)
		{
			if (resolverEnabled) {
				ResolveResult result = errorResult;
				if (resolver.CurrentMember != null) {
					result = new MemberResolveResult(null, resolver.CurrentMember, false);
				}
				ResolveAndProcessConversion(fixedVariableInitializer.CountExpression, resolver.Compilation.FindType(KnownTypeCode.Int32));
				return result;
			} else {
				ScanChildren(fixedVariableInitializer);
				return null;
			}
		}
		
		ResolveResult VisitMethodMember(EntityDeclaration memberDeclaration)
		{
			CSharpResolver oldResolver = resolver;
			try {
				IMember member = null;
				if (unresolvedFile != null) {
					member = GetMemberFromLocation(memberDeclaration);
				}
				if (member == null) {
					// Re-discover the method:
					SymbolKind symbolKind = memberDeclaration.SymbolKind;
					var parameterTypes = TypeSystemConvertVisitor.GetParameterTypes(memberDeclaration.GetChildrenByRole(Roles.Parameter), InterningProvider.Dummy);
					if (symbolKind == SymbolKind.Constructor) {
						string name = memberDeclaration.HasModifier(Modifiers.Static) ? ".cctor" : ".ctor";
						member = AbstractUnresolvedMember.Resolve(
							resolver.CurrentTypeResolveContext, symbolKind, name,
							parameterTypeReferences: parameterTypes);
					} else if (symbolKind == SymbolKind.Destructor) {
						member = AbstractUnresolvedMember.Resolve(resolver.CurrentTypeResolveContext, symbolKind, "Finalize");
					} else {
						string[] typeParameterNames = memberDeclaration.GetChildrenByRole(Roles.TypeParameter).Select(tp => tp.Name).ToArray();
						AstType explicitInterfaceAstType = memberDeclaration.GetChildByRole(EntityDeclaration.PrivateImplementationTypeRole);
						ITypeReference explicitInterfaceType = null;
						if (!explicitInterfaceAstType.IsNull) {
							explicitInterfaceType = explicitInterfaceAstType.ToTypeReference();
						}
						member = AbstractUnresolvedMember.Resolve(
							resolver.CurrentTypeResolveContext, symbolKind, memberDeclaration.Name,
							explicitInterfaceType, typeParameterNames, parameterTypes);
					}
				}
				resolver = resolver.WithCurrentMember(member);
				ScanChildren(memberDeclaration);
				
				if (member != null)
					return new MemberResolveResult(null, member, false);
				else
					return errorResult;
			} finally {
				resolver = oldResolver;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitMethodDeclaration(MethodDeclaration methodDeclaration)
		{
			return VisitMethodMember(methodDeclaration);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitOperatorDeclaration(OperatorDeclaration operatorDeclaration)
		{
			return VisitMethodMember(operatorDeclaration);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitConstructorDeclaration(ConstructorDeclaration constructorDeclaration)
		{
			return VisitMethodMember(constructorDeclaration);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitDestructorDeclaration(DestructorDeclaration destructorDeclaration)
		{
			return VisitMethodMember(destructorDeclaration);
		}
		
		// handle properties/indexers
		ResolveResult VisitPropertyMember(EntityDeclaration propertyOrIndexerDeclaration)
		{
			CSharpResolver oldResolver = resolver;
			try {
				IMember member;
				if (unresolvedFile != null) {
					member = GetMemberFromLocation(propertyOrIndexerDeclaration);
				} else {
					// Re-discover the property:
					string name = propertyOrIndexerDeclaration.Name;
					var parameterTypeReferences = TypeSystemConvertVisitor.GetParameterTypes(propertyOrIndexerDeclaration.GetChildrenByRole(Roles.Parameter), InterningProvider.Dummy);
					AstType explicitInterfaceAstType = propertyOrIndexerDeclaration.GetChildByRole(EntityDeclaration.PrivateImplementationTypeRole);
					ITypeReference explicitInterfaceType = null;
					if (!explicitInterfaceAstType.IsNull) {
						explicitInterfaceType = explicitInterfaceAstType.ToTypeReference();
					}
					member = AbstractUnresolvedMember.Resolve(
						resolver.CurrentTypeResolveContext, propertyOrIndexerDeclaration.SymbolKind, name,
						explicitInterfaceType, parameterTypeReferences: parameterTypeReferences);
				}
				// We need to use the property as current member so that indexer parameters can be resolved correctly.
				resolver = resolver.WithCurrentMember(member);
				var resolverWithPropertyAsMember = resolver;
				
				for (AstNode node = propertyOrIndexerDeclaration.FirstChild; node != null; node = node.NextSibling) {
					if (node.Role == PropertyDeclaration.GetterRole && member is IProperty) {
						resolver = resolver.WithCurrentMember(((IProperty)member).Getter);
						Scan(node);
						resolver = resolverWithPropertyAsMember;
					} else if (node.Role == PropertyDeclaration.SetterRole && member is IProperty) {
						resolver = resolver.WithCurrentMember(((IProperty)member).Setter);
						Scan(node);
						resolver = resolverWithPropertyAsMember;
					} else {
						Scan(node);
					}
				}
				if (member != null)
					return new MemberResolveResult(null, member, false);
				else
					return errorResult;
			} finally {
				resolver = oldResolver;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitPropertyDeclaration(PropertyDeclaration propertyDeclaration)
		{
			return VisitPropertyMember(propertyDeclaration);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitIndexerDeclaration(IndexerDeclaration indexerDeclaration)
		{
			return VisitPropertyMember(indexerDeclaration);
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitCustomEventDeclaration(CustomEventDeclaration eventDeclaration)
		{
			CSharpResolver oldResolver = resolver;
			try {
				IMember member;
				if (unresolvedFile != null) {
					member = GetMemberFromLocation(eventDeclaration);
				} else {
					string name = eventDeclaration.Name;
					AstType explicitInterfaceAstType = eventDeclaration.PrivateImplementationType;
					if (explicitInterfaceAstType.IsNull) {
						member = AbstractUnresolvedMember.Resolve(resolver.CurrentTypeResolveContext, SymbolKind.Event, name);
					} else {
						member = AbstractUnresolvedMember.Resolve(resolver.CurrentTypeResolveContext, SymbolKind.Event, name,
						                                          explicitInterfaceAstType.ToTypeReference());
					}
				}
				resolver = resolver.WithCurrentMember(member);
				var resolverWithEventAsMember = resolver;
				
				for (AstNode node = eventDeclaration.FirstChild; node != null; node = node.NextSibling) {
					if (node.Role == CustomEventDeclaration.AddAccessorRole && member is IEvent) {
						resolver = resolver.WithCurrentMember(((IEvent)member).AddAccessor);
						Scan(node);
						resolver = resolverWithEventAsMember;
					} else if (node.Role == CustomEventDeclaration.RemoveAccessorRole && member is IEvent) {
						resolver = resolver.WithCurrentMember(((IEvent)member).RemoveAccessor);
						Scan(node);
						resolver = resolverWithEventAsMember;
					} else {
						Scan(node);
					}
				}

				if (member != null)
					return new MemberResolveResult(null, member, false);
				else
					return errorResult;
			} finally {
				resolver = oldResolver;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitParameterDeclaration(ParameterDeclaration parameterDeclaration)
		{
			ScanChildren(parameterDeclaration);
			if (resolverEnabled) {
				string name = parameterDeclaration.Name;
				
				if (parameterDeclaration.Parent is DocumentationReference) {
					// create a dummy parameter
					IType type = ResolveType(parameterDeclaration.Type);
					switch (parameterDeclaration.ParameterModifier) {
						case ParameterModifier.Ref:
						case ParameterModifier.Out:
							type = new ByReferenceType(type);
							break;
					}
					return new LocalResolveResult(new DefaultParameter(
						type, name,
						isRef: parameterDeclaration.ParameterModifier == ParameterModifier.Ref,
						isOut: parameterDeclaration.ParameterModifier == ParameterModifier.Out,
						isParams: parameterDeclaration.ParameterModifier == ParameterModifier.Params));
				}
				
				// Look in lambda parameters:
				foreach (IParameter p in resolver.LocalVariables.OfType<IParameter>()) {
					if (p.Name == name)
						return new LocalResolveResult(p);
				}
				
				IParameterizedMember pm = resolver.CurrentMember as IParameterizedMember;
				if (pm == null && resolver.CurrentTypeDefinition != null) {
					// Also consider delegate parameters:
					pm = resolver.CurrentTypeDefinition.GetDelegateInvokeMethod();
					// pm will be null if the current type isn't a delegate
				}
				if (pm != null) {
					foreach (IParameter p in pm.Parameters) {
						if (p.Name == name) {
							return new LocalResolveResult(p);
						}
					}
				}
				
				return errorResult;
			} else {
				return null;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitTypeParameterDeclaration(TypeParameterDeclaration typeParameterDeclaration)
		{
			ScanChildren(typeParameterDeclaration);
			if (resolverEnabled) {
				string name = typeParameterDeclaration.Name;
				IMethod m = resolver.CurrentMember as IMethod;
				if (m != null) {
					foreach (var tp in m.TypeParameters) {
						if (tp.Name == name)
							return new TypeResolveResult(tp);
					}
				}
				if (resolver.CurrentTypeDefinition != null) {
					var typeParameters = resolver.CurrentTypeDefinition.TypeParameters;
					// look backwards so that TPs in the current type take precedence over those copied from outer types
					for (int i = typeParameters.Count - 1; i >= 0; i--) {
						if (typeParameters[i].Name == name)
							return new TypeResolveResult(typeParameters[i]);
					}
				}
				return errorResult;
			} else {
				return null;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitEnumMemberDeclaration(EnumMemberDeclaration enumMemberDeclaration)
		{
			CSharpResolver oldResolver = resolver;
			try {
				// Scan enum member attributes before setting resolver.CurrentMember, so that
				// enum values used as attribute arguments have the correct type.
				// (within an enum member, all other enum members are treated as having their underlying type)
				foreach (var attributeSection in enumMemberDeclaration.Attributes)
					Scan(attributeSection);
				
				IMember member = null;
				if (unresolvedFile != null) {
					member = GetMemberFromLocation(enumMemberDeclaration);
				} else if (resolver.CurrentTypeDefinition != null) {
					string name = enumMemberDeclaration.Name;
					member = resolver.CurrentTypeDefinition.GetFields(f => f.Name == name, GetMemberOptions.IgnoreInheritedMembers).FirstOrDefault();
				}
				resolver = resolver.WithCurrentMember(member);
				
				if (resolverEnabled && resolver.CurrentTypeDefinition != null) {
					ResolveAndProcessConversion(enumMemberDeclaration.Initializer, resolver.CurrentTypeDefinition.EnumUnderlyingType);
					if (resolverEnabled && member != null)
						return new MemberResolveResult(null, member, false);
					else
						return errorResult;
				} else {
					Scan(enumMemberDeclaration.Initializer);
					return null;
				}
			} finally {
				resolver = oldResolver;
			}
		}
		#endregion
		
		#region Track CheckForOverflow
		ResolveResult IAstVisitor<ResolveResult>.VisitCheckedExpression(CheckedExpression checkedExpression)
		{
			CSharpResolver oldResolver = resolver;
			try {
				resolver = resolver.WithCheckForOverflow(true);
				if (resolverEnabled) {
					return Resolve(checkedExpression.Expression);
				} else {
					ScanChildren(checkedExpression);
					return null;
				}
			} finally {
				resolver = oldResolver;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitUncheckedExpression(UncheckedExpression uncheckedExpression)
		{
			CSharpResolver oldResolver = resolver;
			try {
				resolver = resolver.WithCheckForOverflow(false);
				if (resolverEnabled) {
					return Resolve(uncheckedExpression.Expression);
				} else {
					ScanChildren(uncheckedExpression);
					return null;
				}
			} finally {
				resolver = oldResolver;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitCheckedStatement(CheckedStatement checkedStatement)
		{
			CSharpResolver oldResolver = resolver;
			try {
				resolver = resolver.WithCheckForOverflow(true);
				ScanChildren(checkedStatement);
				return voidResult;
			} finally {
				resolver = oldResolver;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitUncheckedStatement(UncheckedStatement uncheckedStatement)
		{
			CSharpResolver oldResolver = resolver;
			try {
				resolver = resolver.WithCheckForOverflow(false);
				ScanChildren(uncheckedStatement);
				return voidResult;
			} finally {
				resolver = oldResolver;
			}
		}
		#endregion
		
		#region Visit AnonymousTypeCreateExpression
		static string GetAnonymousTypePropertyName(Expression expr, out Expression resolveExpr)
		{
			if (expr is NamedExpression) {
				var namedArgExpr = (NamedExpression)expr;
				resolveExpr = namedArgExpr.Expression;
				return namedArgExpr.Name;
			}
			// no name given, so it's a projection initializer
			if (expr is MemberReferenceExpression) {
				resolveExpr = expr;
				return ((MemberReferenceExpression)expr).MemberName;
			}
			if (expr is IdentifierExpression) {
				resolveExpr = expr;
				return ((IdentifierExpression)expr).Identifier;
			}
			resolveExpr = null;
			return null;
		}
		
		class AnonymousTypeMember
		{
			public readonly Expression Expression;
			public readonly ResolveResult Initializer;
			
			public AnonymousTypeMember(Expression expression, ResolveResult initializer)
			{
				this.Expression = expression;
				this.Initializer = initializer;
			}
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitAnonymousTypeCreateExpression(AnonymousTypeCreateExpression anonymousTypeCreateExpression)
		{
			// 7.6.10.6 Anonymous object creation expressions
			List<IUnresolvedProperty> unresolvedProperties = new List<IUnresolvedProperty>();
			List<AnonymousTypeMember> members = new List<AnonymousTypeMember>();
			foreach (var expr in anonymousTypeCreateExpression.Initializers) {
				Expression resolveExpr;
				var name = GetAnonymousTypePropertyName(expr, out resolveExpr);
				if (resolveExpr != null) {
					var initRR = Resolve(resolveExpr);
					var returnTypeRef = initRR.Type.ToTypeReference();
					var property = new DefaultUnresolvedProperty();
					property.Name = name;
					property.Accessibility = Accessibility.Public;
					property.ReturnType = returnTypeRef;
					property.Getter = new DefaultUnresolvedMethod {
						Name = "get_" + name,
						Accessibility = Accessibility.Public,
						ReturnType = returnTypeRef,
						SymbolKind = SymbolKind.Accessor,
						AccessorOwner = property
					};
					unresolvedProperties.Add(property);
					members.Add(new AnonymousTypeMember(expr, initRR));
				} else {
					Scan(expr);
				}
			}
			var anonymousType = new AnonymousType(resolver.Compilation, unresolvedProperties);
			var properties = anonymousType.GetProperties().ToList();
			Debug.Assert(properties.Count == members.Count);
			List<ResolveResult> assignments = new List<ResolveResult>();
			for (int i = 0; i < members.Count; i++) {
				ResolveResult lhs = new MemberResolveResult(new InitializedObjectResolveResult(anonymousType), properties[i]);
				ResolveResult rhs = members[i].Initializer;
				ResolveResult assignment = resolver.ResolveAssignment(AssignmentOperatorType.Assign, lhs, rhs);
				var ne = members[i].Expression as NamedExpression;
				if (ne != null) {
					StoreCurrentState(ne);
					// ne.Expression was already resolved by the first loop
					StoreResult(ne, lhs);
				}
				assignments.Add(assignment);
			}
			var anonymousCtor = DefaultResolvedMethod.GetDummyConstructor(resolver.Compilation, anonymousType);
			return new InvocationResolveResult(null, anonymousCtor, initializerStatements: assignments);
		}
		#endregion
		
		#region Visit Expressions
		ResolveResult IAstVisitor<ResolveResult>.VisitArrayCreateExpression(ArrayCreateExpression arrayCreateExpression)
		{
			int dimensions = arrayCreateExpression.Arguments.Count;
			IEnumerable<Expression> sizeArgumentExpressions;
			ResolveResult[] sizeArguments;
			IEnumerable<ArraySpecifier> additionalArraySpecifiers;
			if (dimensions == 0) {
				var firstSpecifier = arrayCreateExpression.AdditionalArraySpecifiers.FirstOrDefault();
				if (firstSpecifier != null) {
					dimensions = firstSpecifier.Dimensions;
					additionalArraySpecifiers = arrayCreateExpression.AdditionalArraySpecifiers.Skip(1);
				} else {
					// No array specifiers (neither with nor without size) - can happen if there are syntax errors.
					// Dimensions must be at least one; otherwise 'new ArrayType' will crash.
					dimensions = 1;
					additionalArraySpecifiers = arrayCreateExpression.AdditionalArraySpecifiers;
				}
				sizeArguments = null;
				sizeArgumentExpressions = null;
			} else {
				sizeArgumentExpressions = arrayCreateExpression.Arguments;
				sizeArguments = new ResolveResult[dimensions];
				int pos = 0;
				foreach (var node in sizeArgumentExpressions)
					sizeArguments[pos++] = Resolve(node);
				additionalArraySpecifiers = arrayCreateExpression.AdditionalArraySpecifiers;
			}
			
			int[] sizes;
			List<Expression> initializerElements;
			ResolveResult[] initializerElementResults;
			if (arrayCreateExpression.Initializer.IsNull) {
				sizes = null;
				initializerElements = null;
				initializerElementResults = null;
			} else {
				StoreCurrentState(arrayCreateExpression.Initializer);
				
				initializerElements = new List<Expression>();
				sizes = new int[dimensions];
				UnpackArrayInitializer(initializerElements, sizes, arrayCreateExpression.Initializer, 0, true);
				initializerElementResults = new ResolveResult[initializerElements.Count];
				for (int i = 0; i < initializerElementResults.Length; i++) {
					initializerElementResults[i] = Resolve(initializerElements[i]);
				}
				StoreResult(arrayCreateExpression.Initializer, voidResult);
			}
			
			IType elementType;
			if (arrayCreateExpression.Type.IsNull) {
				elementType = null;
			} else {
				elementType = ResolveType(arrayCreateExpression.Type);
				foreach (var spec in additionalArraySpecifiers.Reverse()) {
					elementType = new ArrayType(resolver.Compilation, elementType, spec.Dimensions);
				}
			}
			ArrayCreateResolveResult acrr;
			if (sizeArguments != null) {
				acrr = resolver.ResolveArrayCreation(elementType, sizeArguments, initializerElementResults);
			} else if (sizes != null) {
				acrr = resolver.ResolveArrayCreation(elementType, sizes, initializerElementResults);
			} else {
				// neither size arguments nor an initializer exist -> error
				return new ErrorResolveResult(new ArrayType(resolver.Compilation, elementType ?? SpecialType.UnknownType, dimensions));
			}
			if (sizeArgumentExpressions != null)
				ProcessConversionResults(sizeArgumentExpressions, acrr.SizeArguments);
			if (acrr.InitializerElements != null)
				ProcessConversionResults(initializerElements, acrr.InitializerElements);
			return acrr;
		}
		
		void UnpackArrayInitializer(List<Expression> elementList, int[] sizes, ArrayInitializerExpression initializer, int dimension, bool resolveNestedInitializersToVoid)
		{
			Debug.Assert(dimension < sizes.Length);
			int elementCount = 0;
			if (dimension + 1 < sizes.Length) {
				foreach (var node in initializer.Elements) {
					ArrayInitializerExpression aie = node as ArrayInitializerExpression;
					if (aie != null) {
						if (resolveNestedInitializersToVoid) {
							StoreCurrentState(aie);
							StoreResult(aie, voidResult);
						}
						UnpackArrayInitializer(elementList, sizes, aie, dimension + 1, resolveNestedInitializersToVoid);
					} else {
						elementList.Add(node);
					}
					elementCount++;
				}
			} else {
				foreach (var expr in initializer.Elements) {
					elementList.Add(expr);
					elementCount++;
				}
			}
			if (sizes[dimension] == 0) // 0 = uninitialized
				sizes[dimension] = elementCount;
			else if (sizes[dimension] != elementCount)
				sizes[dimension] = -1; // -1 = error
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitArrayInitializerExpression(ArrayInitializerExpression arrayInitializerExpression)
		{
			// Array initializers are handled by their parent expression.
			ScanChildren(arrayInitializerExpression);
			return errorResult;
		}
		
		ResolveResult IAstVisitor<ResolveResult>.VisitAsExpression(AsExpression asExpression)
		{
			if (resolverEnabled) {
				ResolveResult input = Resolve(asExpression.Exp…