C# AssignmentExpressionSyntax类代码示例

		/// <summary>
		///   Normalizes the <paramref name="assignment" />.
		/// </summary>
		public override SyntaxNode VisitAssignmentExpression(AssignmentExpressionSyntax assignment)
		{
			if (!IsFormulaType(assignment.Left) || IsFormulaType(assignment.Right))
				return base.VisitAssignmentExpression(assignment);

			return assignment.WithRight(CreateInvocation(assignment.Right));
		}

        /// <summary>
        /// Analyzes the ownership of the given-up symbol
        /// in the assignment expression.
        /// </summary>
        /// <param name="givenUpSymbol">GivenUpOwnershipSymbol</param>
        /// <param name="assignment">AssignmentExpressionSyntax</param>
        /// <param name="statement">Statement</param>
        /// <param name="machine">StateMachine</param>
        /// <param name="model">SemanticModel</param>
        /// <param name="trace">TraceInfo</param>
        protected override void AnalyzeOwnershipInAssignment(GivenUpOwnershipSymbol givenUpSymbol,
            AssignmentExpressionSyntax assignment, Statement statement, StateMachine machine,
            SemanticModel model, TraceInfo trace)
        {
            var leftIdentifier = base.AnalysisContext.GetRootIdentifier(assignment.Left);
            ISymbol leftSymbol = model.GetSymbolInfo(leftIdentifier).Symbol;

            if (assignment.Right is IdentifierNameSyntax)
            {
                var rightIdentifier = base.AnalysisContext.GetRootIdentifier(assignment.Right);
                ISymbol rightSymbol = model.GetSymbolInfo(rightIdentifier).Symbol;

                if (statement.Summary.DataFlowAnalysis.FlowsIntoSymbol(rightSymbol,
                    givenUpSymbol.ContainingSymbol, statement, givenUpSymbol.Statement))
                {
                    var type = model.GetTypeInfo(assignment.Right).Type;
                    if (leftSymbol != null && leftSymbol.Kind == SymbolKind.Field &&
                        base.IsFieldAccessedInSuccessor(leftSymbol as IFieldSymbol, statement.Summary, machine) &&
                        !base.AnalysisContext.IsTypePassedByValueOrImmutable(type))
                    {
                        TraceInfo newTrace = new TraceInfo();
                        newTrace.Merge(trace);
                        newTrace.AddErrorTrace(statement.SyntaxNode);

                        AnalysisErrorReporter.ReportGivenUpOwnershipFieldAssignment(newTrace, leftSymbol);
                    }

                    return;
                }
            }
            else if (assignment.Right is MemberAccessExpressionSyntax)
            {
                this.AnalyzeOwnershipInExpression(givenUpSymbol, assignment.Right, statement,
                    machine, model, trace);
            }
            else if (assignment.Right is InvocationExpressionSyntax ||
                assignment.Right is ObjectCreationExpressionSyntax)
            {
                trace.InsertCall(statement.Summary.Method, assignment.Right);
                base.AnalyzeOwnershipInCall(givenUpSymbol, assignment.Right, statement,
                    machine, model, trace);
            }

            if (assignment.Left is MemberAccessExpressionSyntax)
            {
                ISymbol outerLeftMemberSymbol = model.GetSymbolInfo(assignment.Left).Symbol;
                if (!outerLeftMemberSymbol.Equals(leftSymbol) &&
                    statement.Summary.DataFlowAnalysis.FlowsIntoSymbol(givenUpSymbol.ContainingSymbol,
                    leftSymbol, givenUpSymbol.Statement, statement))
                {
                    TraceInfo newTrace = new TraceInfo();
                    newTrace.Merge(trace);
                    newTrace.AddErrorTrace(statement.SyntaxNode);

                    AnalysisErrorReporter.ReportGivenUpOwnershipAccess(newTrace);
                }
            }
        }

        private BoundExpression BindDeconstructionAssignment(AssignmentExpressionSyntax node, DiagnosticBag diagnostics)
        {
            var left = (TupleExpressionSyntax)node.Left;
            ArrayBuilder<DeconstructionVariable> checkedVariables = BindDeconstructionAssignmentVariables(left.Arguments, left, diagnostics);

            var result = BindDeconstructionAssignment(node, node.Right, checkedVariables, diagnostics, isDeclaration: false);
            FreeDeconstructionVariables(checkedVariables);

            return result;
        }

        internal static bool ParseIfStatement(IfStatementSyntax node, out ExpressionSyntax condition, out ExpressionSyntax target, out AssignmentExpressionSyntax whenTrue, out AssignmentExpressionSyntax whenFalse)
        {
            condition = null;
            target = null;
            whenTrue = null;
            whenFalse = null;

            if (node == null || node.Else == null || node.Parent is IfStatementSyntax || node.Else.Statement is IfStatementSyntax)
                return false;

            condition = node.Condition;
            //make sure to check for multiple statements
            ExpressionStatementSyntax whenTrueExprStatement, whenFalseExprStatement;
            var embeddedBlock = node.Statement as BlockSyntax;
            if (embeddedBlock != null)
            {
                if (embeddedBlock.Statements.Count > 1)
                    return false;
                var childNodes = embeddedBlock.ChildNodes();
                if (childNodes.Count() > 1)
                    return false;
                whenTrueExprStatement = childNodes.OfType<ExpressionStatementSyntax>().FirstOrDefault();
            }
            else
            {
                whenTrueExprStatement = node.Statement as ExpressionStatementSyntax;
            }

            var elseBlock = node.Else.Statement as BlockSyntax;
            if (elseBlock != null)
            {
                if (elseBlock.Statements.Count > 1)
                    return false;
                var childNodes = elseBlock.ChildNodes();
                if (childNodes.Count() > 1)
                    return false;
                whenFalseExprStatement = childNodes.OfType<ExpressionStatementSyntax>().FirstOrDefault();
            }
            else
            {
                whenFalseExprStatement = node.Else.Statement as ExpressionStatementSyntax;
            }

            if (whenTrueExprStatement == null || whenFalseExprStatement == null)
                return false;

            whenTrue = whenTrueExprStatement.Expression as AssignmentExpressionSyntax;
            whenFalse = whenFalseExprStatement.Expression as AssignmentExpressionSyntax;
            if (whenTrue == null || whenFalse == null || whenTrue.Kind() != whenFalse.Kind() ||
                !SyntaxFactory.AreEquivalent(whenTrue.Left, whenFalse.Left))
                return false;

            return true;
        }

        public override void VisitAssignmentExpression(AssignmentExpressionSyntax node)
        {
            cb.AppendIndent();
              Visit(node.Left);

              cb.Append(" = ");

              Visit(node.Right);

              cb.AppendLine(";");
        }

        /// <summary>
        /// Analyzes the ownership of the given-up symbol
        /// in the assignment expression.
        /// </summary>
        /// <param name="givenUpSymbol">GivenUpOwnershipSymbol</param>
        /// <param name="assignment">AssignmentExpressionSyntax</param>
        /// <param name="statement">Statement</param>
        /// <param name="machine">StateMachine</param>
        /// <param name="model">SemanticModel</param>
        /// <param name="trace">TraceInfo</param>
        protected override void AnalyzeOwnershipInAssignment(GivenUpOwnershipSymbol givenUpSymbol,
            AssignmentExpressionSyntax assignment, Statement statement, StateMachine machine,
            SemanticModel model, TraceInfo trace)
        {
            IdentifierNameSyntax leftIdentifier = base.AnalysisContext.GetRootIdentifier(assignment.Left);
            ISymbol leftSymbol = model.GetSymbolInfo(leftIdentifier).Symbol;

            this.AnalyzeGivingUpFieldOwnership(givenUpSymbol, leftSymbol, statement, machine, trace);
            this.AnalyzeOwnershipInExpression(givenUpSymbol, assignment.Right,
                statement, machine, model, trace);
        }

 private static SyntaxNode ReplaceAddExpressionByStringBuilderAppendExpression(AssignmentExpressionSyntax assignmentExpression, SyntaxNode expressionStatement, SyntaxNode expressionStatementParent, string builderName)
 {
     var appendExpressionOnLoop = assignmentExpression.IsKind(SyntaxKind.SimpleAssignmentExpression)
         ? SyntaxFactory.ParseStatement($"{builderName}.Append({((BinaryExpressionSyntax)assignmentExpression.Right).Right.ToString()});\r\n")
         : SyntaxFactory.ParseStatement($"{builderName}.Append({assignmentExpression.Right.ToString()});\r\n");
     appendExpressionOnLoop = appendExpressionOnLoop
         .WithLeadingTrivia(expressionStatement.GetLeadingTrivia())
         .WithTrailingTrivia(expressionStatement.GetTrailingTrivia());
     var newExpressionStatementParent = expressionStatementParent.ReplaceNode(expressionStatement, appendExpressionOnLoop);
     return newExpressionStatementParent;
 }

 private static bool IsAssignmentOutsideConstructor(AssignmentExpressionSyntax assignment, ISymbol fieldSymbol, SemanticModel model)
 {
     var assignedSymbol = model.GetSymbolInfo(assignment.Left);
     if (assignedSymbol.Symbol != fieldSymbol)
     {
         return false;
     }
     // Method (or whatever) enclosing the assignment
     var enclosingSymbol = model.GetEnclosingSymbol(assignment.SpanStart) as IMethodSymbol;
     var isCtor = enclosingSymbol?.MethodKind == MethodKind.Constructor;
     return !isCtor;
 }

        static bool CheckConditionAndAssignment(SyntaxNodeAnalysisContext nodeContext, AssignmentExpressionSyntax assignment, BinaryExpressionSyntax condition)
        {
            if (assignment == null)
                return false;

            var assignmentTarget = nodeContext.SemanticModel.GetSymbolInfo(assignment.Left).Symbol;
            if (assignmentTarget == null)
                return false;

            var condLeftSymbol = nodeContext.SemanticModel.GetSymbolInfo(condition.Left).Symbol;
            var condRightSymbol = nodeContext.SemanticModel.GetSymbolInfo(condition.Right).Symbol;

            var assignmentValue = nodeContext.SemanticModel.GetSymbolInfo(assignment.Right).Symbol;
            var constant = nodeContext.SemanticModel.GetConstantValue(assignment.Right);

            bool constantAssignment = assignmentValue == null && constant.HasValue;

            if (assignmentTarget.Equals(condLeftSymbol))
            {
                if (constantAssignment)
                {
                    var condRightValue = nodeContext.SemanticModel.GetConstantValue(condition.Right);
                    if (condRightValue.HasValue)
                        return condRightValue.Value == constant.Value;
                }
                else
                {
                    if ((assignmentValue == null) || !assignmentValue.Equals(condRightSymbol))
                        return false;
                }
                return true;
            }

            // flipped operands
            if (assignmentTarget.Equals(condRightSymbol))
            {
                if (constantAssignment)
                {
                    var condLeftValue = nodeContext.SemanticModel.GetConstantValue(condition.Left);
                    if (condLeftValue.HasValue)
                        return condLeftValue.Value == constant.Value;
                }
                else
                {
                    if ((assignmentValue == null) || !assignmentValue.Equals(condLeftSymbol))
                        return false;
                }
                return true;
            }

            return false;
        }

		/// <summary>
		///   Normalizes the <paramref name="assignment" />.
		/// </summary>
		public override SyntaxNode VisitAssignmentExpression(AssignmentExpressionSyntax assignment)
		{
			var objectCreation = assignment.Right as ObjectCreationExpressionSyntax;
			if (objectCreation == null)
				return assignment;

			var fault = SemanticModel.GetTypeSymbol<Fault>();
			if (SemanticModel.GetTypeInfo(objectCreation).Type?.IsDerivedFrom(fault) == false)
				return assignment;

			var targetSymbol = SemanticModel.GetSymbolInfo(assignment.Left).Symbol;
			if (targetSymbol == null || (targetSymbol.Kind != SymbolKind.Field && targetSymbol.Kind != SymbolKind.Property))
				return assignment;

			return assignment.WithRight(AddNameInitializer(fault, objectCreation, targetSymbol.Name));
		}

 private static MemberAccessExpressionSyntax GetMemberAccessExpressionFromAssignment(SemanticModel semanticModel, AssignmentExpressionSyntax assignmentExpression, AssignmentExpressionSyntax nullLiteralAssignment)
 {
     if (assignmentExpression == null || nullLiteralAssignment == null
         || !assignmentExpression.IsKind(SyntaxKind.SimpleAssignmentExpression)
         || !assignmentExpression.IsKind(SyntaxKind.SimpleAssignmentExpression))
         return null;
     if (!nullLiteralAssignment.Right.IsKind(SyntaxKind.NullLiteralExpression)) return null;
     if (!nullLiteralAssignment.Left.IsKind(SyntaxKind.IdentifierName)) return null;
     if (!assignmentExpression.Left.IsKind(SyntaxKind.IdentifierName)) return null;
     var assignmentIdentifier = semanticModel.GetSymbolInfo(assignmentExpression.Left);
     var nullLiteralAssignmentIdentifier = semanticModel.GetSymbolInfo(nullLiteralAssignment.Left);
     if ((assignmentIdentifier.Symbol ?? nullLiteralAssignmentIdentifier.Symbol) == null) return null;
     if (!assignmentIdentifier.Equals(nullLiteralAssignmentIdentifier)) return null;
     var memberAccessExpression = assignmentExpression.Right as MemberAccessExpressionSyntax;
     return memberAccessExpression;
 }

        private static void AddVariableThatWasSkippedBeforeBecauseItLackedAInitializer(Dictionary<IFieldSymbol, VariableDeclaratorSyntax> variablesToMakeReadonly, IFieldSymbol fieldSymbol, AssignmentExpressionSyntax assignment)
        {
            var parent = assignment.Parent;
            while (parent != null)
            {
                if (parent is AnonymousFunctionExpressionSyntax)
                    return;
                if (parent is ConstructorDeclarationSyntax)
                    break;
                parent = parent.Parent;
            }

            if (!fieldSymbol.IsReadOnly && !variablesToMakeReadonly.Keys.Contains(fieldSymbol))
                foreach (var variable in fieldSymbol.DeclaringSyntaxReferences)
                    variablesToMakeReadonly.Add(fieldSymbol, (VariableDeclaratorSyntax)variable.GetSyntax());
        }

		/// <summary>
		///     Normalizes the <paramref name="expression" /> if it represents a compound assignment.
		/// </summary>
		public override SyntaxNode VisitAssignmentExpression(AssignmentExpressionSyntax expression)
		{
			expression = (AssignmentExpressionSyntax)base.VisitAssignmentExpression(expression);

			SyntaxKind expressionKind;
			switch (expression.Kind())
			{
				case SyntaxKind.AddAssignmentExpression:
					expressionKind = SyntaxKind.AddExpression;
					break;
				case SyntaxKind.SubtractAssignmentExpression:
					expressionKind = SyntaxKind.SubtractExpression;
					break;
				case SyntaxKind.MultiplyAssignmentExpression:
					expressionKind = SyntaxKind.MultiplyExpression;
					break;
				case SyntaxKind.DivideAssignmentExpression:
					expressionKind = SyntaxKind.DivideExpression;
					break;
				case SyntaxKind.ModuloAssignmentExpression:
					expressionKind = SyntaxKind.ModuloExpression;
					break;
				case SyntaxKind.AndAssignmentExpression:
					expressionKind = SyntaxKind.LogicalAndExpression;
					break;
				case SyntaxKind.ExclusiveOrAssignmentExpression:
					expressionKind = SyntaxKind.ExclusiveOrExpression;
					break;
				case SyntaxKind.OrAssignmentExpression:
					expressionKind = SyntaxKind.LogicalOrExpression;
					break;
				case SyntaxKind.LeftShiftAssignmentExpression:
					expressionKind = SyntaxKind.LeftShiftExpression;
					break;
				case SyntaxKind.RightShiftAssignmentExpression:
					expressionKind = SyntaxKind.RightShiftExpression;
					break;
				default:
					return expression;
			}

			var originalRightHand = (ExpressionSyntax)Visit(expression.Right);
			var parenthesizedExpression = SyntaxFactory.ParenthesizedExpression(originalRightHand).WithLeadingSpace();
			var rightHandExpression = SyntaxFactory.BinaryExpression(expressionKind, expression.Left.WithLeadingSpace(), parenthesizedExpression);
			var simpleAssignment = SyntaxFactory.AssignmentExpression(SyntaxKind.SimpleAssignmentExpression, expression.Left, rightHandExpression);
			return simpleAssignment.WithTrivia(expression);
		}

        internal static AssignmentExpressionSyntax CreateAssignment(AssignmentExpressionSyntax node)
        {
            var bop = node.Right as BinaryExpressionSyntax;
            if (bop == null)
                return null;
            var outerLeft = GetOuterLeft(bop);
			var outerLeftId = outerLeft as IdentifierNameSyntax;
			var leftId = node.Left as IdentifierNameSyntax;
			if (outerLeftId == null || leftId == null)
				return null;
			if (!outerLeftId.Identifier.Value.Equals (leftId.Identifier.Value))
                return null;
            var op = GetAssignmentOperator(bop.OperatorToken);
            if (op == SyntaxKind.None)
                return null;
            return SyntaxFactory.AssignmentExpression(op, node.Left, SplitIfWithAndConditionInTwoCodeRefactoringProvider.GetRightSide(outerLeft.Parent as BinaryExpressionSyntax));
        }

		/// <summary>
		///   Normalizes the <paramref name="expression" />.
		/// </summary>
		public override SyntaxNode VisitAssignmentExpression(AssignmentExpressionSyntax expression)
		{
			if (!_inConstructor)
				return expression;

			var propertySymbol = SemanticModel.GetSymbolInfo(expression.Left).Symbol as IPropertySymbol;
			expression = (AssignmentExpressionSyntax)base.VisitAssignmentExpression(expression);

			if (propertySymbol == null || !propertySymbol.IsAutoProperty())
				return expression;

			if (propertySymbol.GetMethod != null && !propertySymbol.GetMethod.CanBeAffectedByFaults(SemanticModel))
				return expression;

			var fieldExpression = (ExpressionSyntax)Syntax.IdentifierName(GetBackingFieldName(propertySymbol)).WithTrivia(expression.Left);
			return expression.WithLeft(fieldExpression);
		}