C# SwitchStatementSyntax类代码示例

 public BoundSwitchStatement(BoundExpression boundCondition, List<BoundCase> boundCases, BoundElse boundElse, SwitchStatementSyntax syntax)
     : base(syntax)
 {
     BoundCondition = boundCondition;
     BoundCases = boundCases;
     BoundElse = boundElse;
 }

 public override SyntaxNode VisitSwitchStatement(SwitchStatementSyntax node)
 {
     var section = node.Sections.FirstOrDefault();
     if (section != null)
     {
         if (_isExpressionTransformer)
         {
             _isExpressionTransformer = false;
             Visit(section);
             if (_transform)
             {
                 _isExpressionTransformer = false;
                 _transform = false;
                 return node.AddSections(
                     Syntax.SwitchSection(
                         Syntax.List(
                             Syntax.SwitchLabel(
                                 SyntaxKind.CaseSwitchLabel,
                                 Syntax.ParseExpression(string.Concat("\"", _expressionTransformerNamespaceDot, _edmxName, "ClientContext\"")))),
                         Syntax.List(
                             Syntax.ParseStatement(string.Concat("return new ", _expressionTransformerNamespaceDot, _edmxName, @"ExpressionTransformer().TransformExpression(expression, contextName);")))));
             }
         }
     }
     return base.VisitSwitchStatement(node);
 }

        //--- Class Methods ---
        public static IEnumerable<ISymbol> GetMissingEnumMembers(SwitchStatementSyntax switchNode, SemanticModel semanticModel, out IdentifierNameSyntax switchVariable)
        {
            // TODO (2016-02-25, steveb): what if the swich calls a function instead?
            switchVariable = switchNode.Expression as IdentifierNameSyntax;
            if(switchVariable == null) {
                return Enumerable.Empty<ISymbol>();
            }
            var switchVariableTypeInfo = semanticModel.GetTypeInfo(switchVariable);

            // check if we are switching over an enum
            if((switchVariableTypeInfo.Type != null) && (switchVariableTypeInfo.Type.TypeKind == TypeKind.Enum)) {

                // get all the enum values
                var enumMembers = switchVariableTypeInfo.Type.GetMembers().Where(x => x.Kind == SymbolKind.Field).ToImmutableArray();

                // get all case statements
                var caseSwitchLabels = switchNode.Sections
                    .SelectMany(section => section.Labels)
                    .Select(label => label.DescendantNodes().OfType<MemberAccessExpressionSyntax>().FirstOrDefault())
                    .Where(memberAccess => memberAccess != null)
                    .Select(memberAccess => semanticModel.GetSymbolInfo(memberAccess).Symbol)
                    .ToImmutableHashSet();

                // make sure we have all cases covered
                return enumMembers.Where(x => !caseSwitchLabels.Contains(x)).ToImmutableArray();
            }
            return Enumerable.Empty<ISymbol>();
        }

        public static string SwitchStatement(SwitchStatementSyntax statement)
        {
            var output = "switch ";
            output += SyntaxNode(statement.Expression) + " {" + NewLine;

            output = statement.Sections.Aggregate(output, (current, sect) => current + SyntaxNode(sect));

            return output + "}" + NewLine;
        }

        private BoundStatement BindSwitchStatement(SwitchStatementSyntax syntax, Symbol parent)
        {
            BindAttributes(syntax.Attributes);

            var switchBinder = new Binder(_sharedBinderState, this);
            var boundSections = syntax.Sections.Select(x => switchBinder.Bind(x, y => switchBinder.BindSwitchSection(y, parent))).ToImmutableArray();

            return new BoundSwitchStatement(
                Bind(syntax.Expression, BindExpression),
                boundSections);
        }

        private static bool HasPatternSwitchSyntax(SwitchStatementSyntax switchSyntax)
        {
            foreach (var section in switchSyntax.Sections)
            {
                if (section.Labels.Any(SyntaxKind.CasePatternSwitchLabel))
                {
                    return true;
                }
            }

            return false;
        }

        private bool DefaultSectionThrows(SwitchStatementSyntax switchStatement, SemanticModel semanticModel)
        {
            var defaultCase = switchStatement.Sections.FirstOrDefault(s => s.Labels.OfType<DefaultSwitchLabelSyntax>().Any());

            if (defaultCase == null)
            {
                return false;
            }

            bool throwsInvalidOperation =
                defaultCase.Statements
                    // Filtering throw
                    .OfType<ThrowStatementSyntax>()
                    .Select(s => s.Expression)
                    // Filtering throw new Exception
                    .OfType<ObjectCreationExpressionSyntax>()
                    // Filtering unknown symbols
                    .Select(s => semanticModel.GetSymbolInfo(s.Type).Symbol)
                    .Where(s => s != null)
                    // True, if throw new InvalidOperationException()
                    .Any(s => s.Equals(semanticModel.GetClrType(typeof(InvalidOperationException))));

            if (throwsInvalidOperation)
            {
                return true;
            }

            bool hasContractAssertOrAssumeWithFalse =
                defaultCase.Statements
                    // Getting only expressions
                    .OfType<ExpressionStatementSyntax>()
                    // that calls functions
                    .Select(s => s.Expression as InvocationExpressionSyntax)
                    .Where(s => s != null)
                    // with first argument equals to false
                    .Where(s =>
                            s.ArgumentList.Arguments.FirstOrDefault()?.Expression?.Kind() == SyntaxKind.FalseLiteralExpression)
                    // with known symbols
                    .Select(s => semanticModel.GetSymbolInfo(s).Symbol as IMethodSymbol)
                    .Where(s => s != null)
                    // Contract.Assert/Assume or Debug.Assert
                    .Any(m => (m.ContainingType.Equals(semanticModel.GetClrType(typeof(Contract))) &&
                               (m.Name == "Assert" || m.Name == "Assume")) ||
                              (m.ContainingType.Name == "Debug" && m.Name == "Assert"));

            if (hasContractAssertOrAssumeWithFalse)
            {
                return true;
            }

            return false;
        }

 internal static SwitchBinder Create(Binder next, SwitchStatementSyntax switchSyntax)
 {
     var parseOptions = switchSyntax?.SyntaxTree?.Options as CSharpParseOptions;
     return
         // In C# 6 and earlier, we use the old binder. In C# 7 and later, we use the new binder which
         // is capable of binding both the old and new syntax. However, the new binder does not yet
         // lead to a translation that fully supports edit-and-continue, so it delegates to the C# 6
         // binder when it can. The "typeswitch" feature flag forces the use of the C# 7 switch binder
         // for all operations; we use it to enhance test coverage.
         (parseOptions?.IsFeatureEnabled(MessageID.IDS_FeaturePatternMatching) != false || parseOptions?.Features.ContainsKey("typeswitch") != false)
         ? new PatternSwitchBinder(next, switchSyntax)
         : new SwitchBinder(next, switchSyntax);
 }

		private async Task<Document> ExplodeSwitch(Document document, 
			SyntaxNode root, 
			SemanticModel semanticModel, 
			SwitchStatementSyntax node, 
			CancellationToken cancellationToken)
		{
			var switchRewriter = new SwitchSyntaxRewriter(semanticModel);
			var newNode = switchRewriter.VisitSwitchStatement(node);

			root = root.ReplaceNode(node, newNode);
			document = document.WithSyntaxRoot(root);

			return await Formatter.FormatAsync(document, null, cancellationToken).ConfigureAwait(false);
		}

        public SwitchAnalyzer(SwitchStatementSyntax switchStatement, SemanticModel semanticModel)
        {
            // Hm...! It seems that Code Contracts still has a bug, and uncommenting Contract.Requires lead to NRE!
            //Contract.Requires(switchStatement != null);
            //Contract.Requires(semanticModel != null);

            _switchStatement = switchStatement;
            _semanticModel = semanticModel;

            var expressionSymbol = semanticModel.GetSymbolInfo(switchStatement.Expression).Symbol;
            _expressionType = LazyEx.Create(() => GetSymbolType(expressionSymbol));
            _switchOverEnum = LazyEx.Create(() => _expressionType.Value.IsEnum());
            _enumValues = LazyEx.Create(() => _expressionType.Value.GetSortedEnumFieldsAndValues().ToImmutableList());
            _cases = LazyEx.Create(() => GetUsedCases().ToImmutableList());
        }

        internal override BoundStatement BindSwitchExpressionAndSections(SwitchStatementSyntax node, Binder originalBinder, DiagnosticBag diagnostics)
        {
            // If it is a valid C# 6 switch statement, we use the old binder to bind it.
            if (!UseV7SwitchBinder) return base.BindSwitchExpressionAndSections(node, originalBinder, diagnostics);

            Debug.Assert(SwitchSyntax.Equals(node));

            // Bind switch expression and set the switch governing type.
            var boundSwitchExpression = SwitchGoverningExpression;
            diagnostics.AddRange(SwitchGoverningDiagnostics);

            BoundPatternSwitchLabel defaultLabel;
            ImmutableArray<BoundPatternSwitchSection> switchSections = BindPatternSwitchSections(boundSwitchExpression, node.Sections, originalBinder, out defaultLabel, diagnostics);
            var locals = GetDeclaredLocalsForScope(node);
            var functions = GetDeclaredLocalFunctionsForScope(node);
            return new BoundPatternSwitchStatement(
                node, boundSwitchExpression,
                locals, functions, switchSections, defaultLabel, this.BreakLabel, this);
        }

        public static List<ExpressionSyntax> GetCaseLabels(SwitchStatementSyntax switchStatement, out bool containsDefaultLabel)
        {
            containsDefaultLabel = false;

            var caseLabels = new List<ExpressionSyntax>();
            foreach (var section in switchStatement.Sections)
            {
                foreach (var label in section.Labels)
                {
                    var caseLabel = label as CaseSwitchLabelSyntax;
                    if (caseLabel != null)
                    {
                        caseLabels.Add(caseLabel.Value);
                    }

                    if (label.IsKind(SyntaxKind.DefaultSwitchLabel))
                    {
                        containsDefaultLabel = true;
                    }
                }
            }

            return caseLabels;
        }

 internal virtual BoundSwitchStatement BindSwitchExpressionAndSections(SwitchStatementSyntax node, Binder originalBinder, DiagnosticBag diagnostics)
 {
     return this.Next.BindSwitchExpressionAndSections(node, originalBinder, diagnostics);
 }

 private static bool HasAtLeastThreeLabels(SwitchStatementSyntax node)
 {
     return node.Sections.Sum(section => section.Labels.Count) >= 3;
 }

        internal override BoundStatement BindSwitchExpressionAndSections(SwitchStatementSyntax node, Binder originalBinder, DiagnosticBag diagnostics)
        {
            Debug.Assert(SwitchSyntax.Equals(node));

            // Bind switch expression and set the switch governing type.
            var boundSwitchExpression = this.SwitchGoverningExpression;
            diagnostics.AddRange(this.SwitchGoverningDiagnostics);

            // Switch expression might be a constant expression.
            // For this scenario we can determine the target label of the switch statement
            // at compile time.            
            LabelSymbol constantTargetOpt = null;
            var constantValue = boundSwitchExpression.ConstantValue;
            if (constantValue != null)
            {
                constantTargetOpt = BindConstantJumpTarget(constantValue, node);
            }
            else if (!node.Sections.Any())
            {
                // empty switch block, set the break label as target
                constantTargetOpt = this.BreakLabel;
            }

            // Bind switch section
            ImmutableArray<BoundSwitchSection> boundSwitchSections = BindSwitchSections(node.Sections, originalBinder, diagnostics);

            return new BoundSwitchStatement(node, null, boundSwitchExpression, constantTargetOpt, 
                                            GetDeclaredLocalsForScope(node), 
                                            GetDeclaredLocalFunctionsForScope(node), boundSwitchSections, this.BreakLabel, null);
        }