C# SyntaxContext类代码示例

		protected override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var position = completionContext.Position;
			var document = completionContext.Document;
			var syntaxTree = ctx.SyntaxTree;
			if (syntaxTree.IsInNonUserCode(position, cancellationToken) ||
				syntaxTree.IsPreProcessorDirectiveContext(position, cancellationToken))
				return Task.FromResult (Enumerable.Empty<CompletionData> ());
			if (!syntaxTree.IsRightOfDotOrArrowOrColonColon(position, cancellationToken))
				return Task.FromResult (Enumerable.Empty<CompletionData> ());
			var ma = ctx.LeftToken.Parent as MemberAccessExpressionSyntax;
			if (ma == null)
				return Task.FromResult (Enumerable.Empty<CompletionData> ());

			var model = ctx.CSharpSyntaxContext.SemanticModel;

			var symbolInfo = model.GetSymbolInfo (ma.Expression);
			if (symbolInfo.Symbol == null || symbolInfo.Symbol.Kind != SymbolKind.Parameter)
				return Task.FromResult (Enumerable.Empty<CompletionData> ());
			var list = new List<CompletionData> ();
			var within = model.GetEnclosingNamedTypeOrAssembly(position, cancellationToken);
			var addedSymbols = new HashSet<string> ();

			foreach (var ano in ma.AncestorsAndSelf ().OfType<AnonymousMethodExpressionSyntax> ()) {
				Analyze (engine, model, ma.Expression, within, list, ano.ParameterList, symbolInfo.Symbol, addedSymbols, cancellationToken);
			}

			foreach (var ano in ma.AncestorsAndSelf ().OfType<ParenthesizedLambdaExpressionSyntax> ()) {
				Analyze (engine, model, ma.Expression, within, list, ano.ParameterList, symbolInfo.Symbol, addedSymbols, cancellationToken);
			}

			return Task.FromResult ((IEnumerable<CompletionData>)list);
		}

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var model = ctx.SemanticModel;
			var tree = ctx.SyntaxTree;
			if (tree.IsInNonUserCode (completionContext.Position, cancellationToken))
				return Enumerable.Empty<CompletionData> ();

			var token = tree.FindTokenOnLeftOfPosition (completionContext.Position, cancellationToken);
			if (token.IsMandatoryNamedParameterPosition ())
				return Enumerable.Empty<CompletionData> ();
			var result = new List<CompletionData> ();

			// check if it's the first parameter and set autoselect == false if a parameterless version exists.
			if (token.IsKind (SyntaxKind.OpenParenToken)) {
				var parent = token.Parent?.Parent;
				if (parent == null)
					return Enumerable.Empty<CompletionData> ();
				var symbolInfo = model.GetSymbolInfo (parent);
				foreach (var symbol in new [] { symbolInfo.Symbol }.Concat (symbolInfo.CandidateSymbols)) {
					if (symbol != null && symbol.IsKind (SymbolKind.Method)) {
						if (symbol.GetParameters ().Length == 0) {
							completionResult.AutoSelect = false;
							break;
						}
					}
				}
			}

			foreach (var _type in ctx.InferredTypes) {
				var type = _type;
				if (type.OriginalDefinition.SpecialType == SpecialType.System_Nullable_T) {
					type = type.GetTypeArguments ().FirstOrDefault ();
					if (type == null)
						continue;
				}

				if (type.TypeKind != TypeKind.Enum)
					continue;
				if (!type.IsEditorBrowsable ())
					continue;

				// Does type have any aliases?
				ISymbol alias = await type.FindApplicableAlias (completionContext.Position, model, cancellationToken).ConfigureAwait (false);

				var displayString = RoslynCompletionData.SafeMinimalDisplayString (type, model, completionContext.Position, SymbolDisplayFormat.CSharpErrorMessageFormat);
				if (string.IsNullOrEmpty (completionResult.DefaultCompletionString)) {
					completionResult.DefaultCompletionString = displayString;
					completionResult.AutoCompleteEmptyMatch = true;

				}
				if (!IsReachable (model,  type, token.Parent))
					result.Add (engine.Factory.CreateSymbolCompletionData (this, type, displayString));
				foreach (IFieldSymbol field in type.GetMembers ().OfType<IFieldSymbol> ()) {
					if (field.DeclaredAccessibility == Accessibility.Public && (field.IsConst || field.IsStatic)) {
						result.Add (engine.Factory.CreateEnumMemberCompletionData (this, alias, field));
					}
				}
			}
			return result;
		}

		protected override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult result, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var document = completionContext.Document;
			var position = completionContext.Position;

			var tree = ctx.SyntaxTree;
			var model = ctx.SemanticModel;
			if (tree.IsInNonUserCode (position, cancellationToken))
				return Task.FromResult (Enumerable.Empty<CompletionData> ());

			if (!ctx.CSharpSyntaxContext.IsAnyExpressionContext)
				return Task.FromResult (Enumerable.Empty<CompletionData> ());
			var enclosingType = model.GetEnclosingNamedType (position, cancellationToken);
			var memberMethods = enclosingType.GetMembers ().OfType<IMethodSymbol> ().Where (m => m.MethodKind == MethodKind.Ordinary).ToArray ();

			var list = new List<CompletionData> ();
			foreach (var type in ctx.InferredTypes) {
				if (type.TypeKind != TypeKind.Delegate)
					continue;

				AddCompatibleMethods (engine, list, type, memberMethods, cancellationToken);

				string delegateName = null;

				if (ctx.TargetToken.IsKind (SyntaxKind.PlusEqualsToken)) {
					delegateName = GuessEventHandlerBaseName (ctx.LeftToken.Parent, ctx.ContainingTypeDeclaration);
				}

				AddDelegateHandlers (list, ctx.TargetToken.Parent, model, engine, result, type, position, delegateName, cancellationToken);
			}
			if (list.Count > 0) {
				result.AutoSelect = false;
			}
			return Task.FromResult ((IEnumerable<CompletionData>)list);
		}

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var document = completionContext.Document;
			var position = completionContext.Position;
			var tree = ctx.SyntaxTree;

			//DeclarationModifiers modifiers;
			SyntaxToken token;

			var semanticModel = ctx.SemanticModel;
			var enclosingSymbol = semanticModel.GetEnclosingSymbol (position, cancellationToken) as INamedTypeSymbol;

			// Only inside classes and structs
			if (enclosingSymbol == null || !(enclosingSymbol.TypeKind == TypeKind.Struct || enclosingSymbol.TypeKind == TypeKind.Class)) {
				return Enumerable.Empty<CompletionData> ();
			}

			if (!IsPartialCompletionContext (tree, position, cancellationToken/*, out modifiers*/, out token)) {
				if (enclosingSymbol != null && (token.IsKind (SyntaxKind.OpenBraceToken) || token.IsKind (SyntaxKind.CloseBraceToken) || token.IsKind (SyntaxKind.SemicolonToken))) {
					return CreateCompletionData (engine, semanticModel, position, enclosingSymbol, token, false, cancellationToken);
				}
				return Enumerable.Empty<CompletionData> ();
			}

			return CreateCompletionData (engine, semanticModel, position, enclosingSymbol, token, true, cancellationToken);
		}

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var position = completionContext.Position;
			var document = completionContext.Document;
			var span = new TextSpan(position, 0);
			var semanticModel = await document.GetCSharpSemanticModelForSpanAsync(span, cancellationToken).ConfigureAwait(false);
			var syntaxTree = semanticModel.SyntaxTree;
			//	var ctx = await completionContext.GetSyntaxContextAsync (engine.Workspace, cancellationToken).ConfigureAwait (false);

			if (syntaxTree.IsInNonUserCode(position, cancellationToken) ||
				syntaxTree.IsPreProcessorDirectiveContext(position, cancellationToken))
			{
				return Enumerable.Empty<CompletionData> ();
			}

			if (!syntaxTree.IsRightOfDotOrArrowOrColonColon(position, cancellationToken))
			{
				return Enumerable.Empty<CompletionData> ();
			}

			var node = syntaxTree.FindTokenOnLeftOfPosition(position, cancellationToken)
				.GetPreviousTokenIfTouchingWord(position)
				.Parent;

			if (node.Kind() == SyntaxKind.ExplicitInterfaceSpecifier)
			{
				return await GetCompletionsOffOfExplicitInterfaceAsync(
					engine, document, semanticModel, position, ((ExplicitInterfaceSpecifierSyntax)node).Name, cancellationToken).ConfigureAwait(false);
			}

			return Enumerable.Empty<CompletionData> ();
		}

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var document = completionContext.Document;
			var position = completionContext.Position;
			var semanticModel = ctx.SemanticModel;

			if (ctx.TargetToken.Parent != null && ctx.TargetToken.Parent.Parent != null && 
			    ctx.TargetToken.Parent.Parent.IsKind(SyntaxKind.Argument)) {
				SourceText text;
				if (!completionContext.Document.TryGetText (out text)) {
					text = await completionContext.Document.GetTextAsync ();
				}
				var currentChar = text [completionContext.Position - 1];
				if (ctx.TargetToken.Parent == null || !ctx.TargetToken.Parent.IsKind(SyntaxKind.StringLiteralExpression) ||
				    ctx.TargetToken.Parent.Parent == null || !ctx.TargetToken.Parent.Parent.IsKind(SyntaxKind.Argument) ||
				    ctx.TargetToken.Parent.Parent.Parent == null || !ctx.TargetToken.Parent.Parent.Parent.IsKind(SyntaxKind.ArgumentList) ||
				    ctx.TargetToken.Parent.Parent.Parent.Parent == null || !ctx.TargetToken.Parent.Parent.Parent.Parent.IsKind(SyntaxKind.InvocationExpression)) {
					return Enumerable.Empty<CompletionData> ();
				}
				var formatArgument = GetFormatItemNumber(document, position);
				var invocationExpression = ctx.TargetToken.Parent.Parent.Parent.Parent as InvocationExpressionSyntax;
				return GetFormatCompletionData(engine, semanticModel, invocationExpression, formatArgument, currentChar);
			}

			return Enumerable.Empty<CompletionData> ();
		}

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var document = completionContext.Document;
			var position = completionContext.Position;

			var tree = ctx.SyntaxTree;

			if (tree.IsInNonUserCode(position, cancellationToken))
				return Enumerable.Empty<CompletionData> ();

			var targetToken = tree.FindTokenOnLeftOfPosition(position, cancellationToken).GetPreviousTokenIfTouchingWord(position);
			if (targetToken.IsKind(SyntaxKind.AliasKeyword) && targetToken.Parent.IsKind(SyntaxKind.ExternAliasDirective))
			{
				var compilation = await document.GetCSharpCompilationAsync(cancellationToken).ConfigureAwait(false);
				var aliases = compilation.ExternalReferences.Where(r => r.Properties.Aliases != null).SelectMany(r => r.Properties.Aliases).ToSet();

				if (aliases.Any())
				{
					var root = await tree.GetRootAsync(cancellationToken).ConfigureAwait(false);
					var usedAliases = root.ChildNodes().OfType<ExternAliasDirectiveSyntax>().Where(e => !e.Identifier.IsMissing).Select(e => e.Identifier.ValueText);
					foreach (var used in usedAliases) {
						aliases.Remove (used); 
					}
					aliases.Remove(MetadataReferenceProperties.GlobalAlias);
					return aliases.Select (e => engine.Factory.CreateGenericData (this, e, GenericDataType.Undefined));
				}
			}

			return Enumerable.Empty<CompletionData> ();
		}

        /// <summary>
        /// Given a Symbol, creates the completion item for it.
        /// </summary>
        private CompletionItem CreateItem(
            string displayText,
            string insertionText,
            List<ISymbol> symbols,
            SyntaxContext context,
            Dictionary<ISymbol, List<ProjectId>> invalidProjectMap,
            List<ProjectId> totalProjects,
            bool preselect)
        {
            Contract.ThrowIfNull(symbols);

            SupportedPlatformData supportedPlatformData = null;
            if (invalidProjectMap != null)
            {
                List<ProjectId> invalidProjects = null;
                foreach (var symbol in symbols)
                {
                    if (invalidProjectMap.TryGetValue(symbol, out invalidProjects))
                    {
                        break;
                    }
                }

                if (invalidProjects != null)
                {
                    supportedPlatformData = new SupportedPlatformData(invalidProjects, totalProjects, context.Workspace);
                }
            }

            return CreateItem(displayText, insertionText, symbols, context, preselect, supportedPlatformData);
        }

        protected override IEnumerable<INamedTypeSymbol> LookupCandidateSymbols(SyntaxContext context, INamedTypeSymbol declaredSymbol, CancellationToken cancellationToken)
        {
            var candidates = base.LookupCandidateSymbols(context, declaredSymbol, cancellationToken);

            // The base class applies a broad filter when finding candidates, but since C# requires
            // that all parts have the "partial" modifier, the results can be trimmed further here.
            return candidates?.Where(symbol => symbol.DeclaringSyntaxReferences.Any(reference => IsPartialTypeDeclaration(reference.GetSyntax(cancellationToken))));
        }

		public override async Task<bool> IsExclusiveAsync (CompletionContext completionContext, SyntaxContext syntaxContext, CompletionTriggerInfo triggerInfo, CancellationToken cancellationToken)
		{
			// We're exclusive if this context could only be an object initializer and not also a
			// collection initializer. If we're initializing something that could be initialized as
			// an object or as a collection, say we're not exclusive. That way the rest of
			// intellisense can be used in the collection intitializer.
			// 
			// Consider this case:

			// class c : IEnumerable<int> 
			// { 
			// public void Add(int addend) { }
			// public int foo; 
			// }

			// void foo()
			// {
			//    var b = new c {|
			// }

			// There we could initialize b using either an object initializer or a collection
			// initializer. Since we don't know which the user will use, we'll be non-exclusive, so
			// the other providers can help the user write the collection initializer, if they want
			// to.
			var document = completionContext.Document;
			var position = completionContext.Position;
			var tree = await document.GetCSharpSyntaxTreeAsync (cancellationToken).ConfigureAwait (false);

			if (tree.IsInNonUserCode (position, cancellationToken)) {
				return false;
			}

			var token = tree.FindTokenOnLeftOfPosition (position, cancellationToken);
			token = token.GetPreviousTokenIfTouchingWord (position);

			if (token.Parent == null) {
				return false;
			}

			var expression = token.Parent.Parent as ExpressionSyntax;
			if (expression == null) {
				return false;
			}

			var semanticModel = await document.GetCSharpSemanticModelForNodeAsync (expression, cancellationToken).ConfigureAwait (false);
			var initializedType = semanticModel.GetTypeInfo (expression, cancellationToken).Type;
			if (initializedType == null) {
				return false;
			}

			// Non-exclusive if initializedType can be initialized as a collection.
			if (initializedType.CanSupportCollectionInitializer ()) {
				return false;
			}

			// By default, only our member names will show up.
			return true;
		}

        protected override (string displayText, string insertionText) GetDisplayAndInsertionText(ISymbol symbol, SyntaxContext context)
        {
            if (symbol is IAliasSymbol)
            {
                return (symbol.Name, symbol.Name);
            }

            return base.GetDisplayAndInsertionText(symbol, context);
        }

        protected override ValueTuple<string, string> GetDisplayAndInsertionText(ISymbol symbol, SyntaxContext context)
        {
            if (symbol is IAliasSymbol)
            {
                return ValueTuple.Create(symbol.Name, symbol.Name);
            }

            return base.GetDisplayAndInsertionText(symbol, context);
        }

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var document = completionContext.Document;
			var position = completionContext.Position;

			return await document.GetUnionResultsFromDocumentAndLinks(
				UnionCompletionItemComparer.Instance,
				async (doc, ct) => await GetSpeculativeTCompletions(engine, doc, position, ct).ConfigureAwait(false),
				cancellationToken).ConfigureAwait(false);
		}

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var document = completionContext.Document;
			var position = completionContext.Position;

			var syntaxTree = await document.GetCSharpSyntaxTreeAsync(cancellationToken).ConfigureAwait(false);

			if (syntaxTree.IsInNonUserCode(position, cancellationToken) ||
				syntaxTree.IsRightOfDotOrArrowOrColonColon(position, cancellationToken) ||
				syntaxTree.GetContainingTypeOrEnumDeclaration(position, cancellationToken) is EnumDeclarationSyntax)
			{
				return Enumerable.Empty<CompletionData>();
			}

			// var span = new TextSpan(position, 0);
//			var semanticModel = await document.GetCSharpSemanticModelForSpanAsync(span, cancellationToken).ConfigureAwait(false);
			if (syntaxTree.IsPreProcessorDirectiveContext(position, cancellationToken))
			{
				var directive = syntaxTree.GetRoot(cancellationToken).FindTokenOnLeftOfPosition(position, includeDirectives: true).GetAncestor<DirectiveTriviaSyntax>();
				if (directive.DirectiveNameToken.IsKind(
					SyntaxKind.IfKeyword,
					SyntaxKind.RegionKeyword,
					SyntaxKind.ElseKeyword,
					SyntaxKind.ElifKeyword,
					SyntaxKind.ErrorKeyword,
					SyntaxKind.LineKeyword,
					SyntaxKind.PragmaKeyword,
					SyntaxKind.EndIfKeyword,
					SyntaxKind.UndefKeyword,
					SyntaxKind.EndRegionKeyword,
					SyntaxKind.WarningKeyword))
				{
					return Enumerable.Empty<CompletionData>();
				}

				return await GetSnippetCompletionItemsAsync(cancellationToken).ConfigureAwait(false);
			}
			var tokenLeftOfPosition = syntaxTree.FindTokenOnLeftOfPosition (position, cancellationToken);

			if (syntaxTree.IsGlobalStatementContext(position, cancellationToken) ||
				syntaxTree.IsExpressionContext(position, tokenLeftOfPosition, true, cancellationToken) ||
				syntaxTree.IsStatementContext(position, tokenLeftOfPosition, cancellationToken) ||
				syntaxTree.IsTypeContext(position, cancellationToken) ||
				syntaxTree.IsTypeDeclarationContext(position, tokenLeftOfPosition, cancellationToken) ||
				syntaxTree.IsNamespaceContext(position, cancellationToken) ||
				syntaxTree.IsMemberDeclarationContext(position, tokenLeftOfPosition, cancellationToken) ||
				syntaxTree.IsLabelContext(position, cancellationToken))
			{
				return await GetSnippetCompletionItemsAsync(cancellationToken).ConfigureAwait(false);
			}

			return Enumerable.Empty<CompletionData>();
		}

		protected async override Task<IEnumerable<CompletionData>> GetItemsWorkerAsync (CompletionResult completionResult, CompletionEngine engine, CompletionContext completionContext, CompletionTriggerInfo info, SyntaxContext ctx, CancellationToken cancellationToken)
		{
			var model = ctx.SemanticModel;

			var result = new List<CompletionData> ();
			if (ctx.IsPreProcessorExpressionContext) {
				var parseOptions = model.SyntaxTree.Options as CSharpParseOptions;
				foreach (var define in parseOptions.PreprocessorSymbolNames) {
					result.Add(engine.Factory.CreateGenericData (this, define, GenericDataType.PreprocessorSymbol));
				}
			}
			return result;
		}