public static bool CanRefactor(
SwitchStatementSyntax switchStatement,
SemanticModel semanticModel,
CancellationToken cancellationToken)
{
ExpressionSyntax expression = switchStatement.Expression;
if (expression == null)
{
return(false);
}
if (!IsEmptyOrContainsOnlyDefaultSection(switchStatement))
{
return(false);
}
ISymbol symbol = semanticModel.GetSymbol(expression, cancellationToken);
if (symbol?.IsErrorType() != false)
{
return(false);
}
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(expression, cancellationToken);
return(typeSymbol?.TypeKind == TypeKind.Enum &&
typeSymbol.ContainsMember <IFieldSymbol>());
}
public static async Task <Document> RefactorAsync(
Document document,
BinaryExpressionSyntax binaryExpression,
ITypeSymbol typeSymbol,
CancellationToken cancellationToken)
{
SemanticModel semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
ExpressionSyntax right = binaryExpression.Right;
ExpressionSyntax newNode = null;
if (CSharpFacts.IsSimpleType(typeSymbol.SpecialType) ||
typeSymbol.ContainsMember <IMethodSymbol>(WellKnownMemberNames.EqualityOperatorName))
{
newNode = typeSymbol.GetDefaultValueSyntax(semanticModel, right.SpanStart)
.WithTriviaFrom(right)
.WithFormatterAnnotation();
return(await document.ReplaceNodeAsync(right, newNode, cancellationToken).ConfigureAwait(false));
}
else
{
INamedTypeSymbol equalityComparerSymbol = semanticModel
.GetTypeByMetadataName(MetadataNames.System_Collections_Generic_EqualityComparer_T)
.Construct(typeSymbol);
newNode = InvocationExpression(
SimpleMemberAccessExpression(
SimpleMemberAccessExpression(equalityComparerSymbol.ToMinimalTypeSyntax(semanticModel, binaryExpression.SpanStart), IdentifierName("Default")), IdentifierName("Equals")),
ArgumentList(
Argument(binaryExpression.Left.WithoutTrivia()),
Argument(DefaultExpression(typeSymbol.ToMinimalTypeSyntax(semanticModel, right.SpanStart)))));
if (binaryExpression.IsKind(SyntaxKind.NotEqualsExpression))
{
newNode = LogicalNotExpression(newNode);
}
newNode = newNode
.WithTriviaFrom(binaryExpression)
.WithFormatterAnnotation();
return(await document.ReplaceNodeAsync(binaryExpression, newNode, cancellationToken).ConfigureAwait(false));
}
}
public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
{
SyntaxNode root = await context.GetSyntaxRootAsync().ConfigureAwait(false);
if (!TryFindFirstAncestorOrSelf(root, context.Span, out BinaryExpressionSyntax binaryExpression))
{
return;
}
Document document = context.Document;
foreach (Diagnostic diagnostic in context.Diagnostics)
{
switch (diagnostic.Id)
{
case DiagnosticIdentifiers.SimplifyBooleanComparison:
{
CodeAction codeAction = CodeAction.Create(
"Simplify boolean comparison",
cancellationToken => SimplifyBooleanComparisonRefactoring.RefactorAsync(document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.CallSkipAndAnyInsteadOfCount:
{
CodeAction codeAction = CodeAction.Create(
"Call 'Skip' and 'Any' instead of 'Count'",
cancellationToken => CallSkipAndAnyInsteadOfCountRefactoring.RefactorAsync(document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.ConstantValuesShouldBePlacedOnRightSideOfComparisons:
{
CodeAction codeAction = CodeAction.Create(
"Swap operands",
cancellationToken => document.ReplaceNodeAsync(binaryExpression, SyntaxRefactorings.SwapBinaryOperands(binaryExpression), cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseStringIsNullOrEmptyMethod:
{
CodeAction codeAction = CodeAction.Create(
"Use 'string.IsNullOrEmpty' method",
cancellationToken => UseStringIsNullOrEmptyMethodAsync(document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.SimplifyCoalesceExpression:
{
ExpressionSyntax expression = binaryExpression.Left;
if (expression == null ||
!context.Span.Contains(expression.Span))
{
expression = binaryExpression.Right;
}
CodeAction codeAction = CodeAction.Create(
"Simplify coalesce expression",
cancellationToken => SimplifyCoalesceExpressionRefactoring.RefactorAsync(document, binaryExpression, expression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.RemoveRedundantAsOperator:
{
CodeAction codeAction = CodeAction.Create(
"Remove redundant 'as' operator",
cancellationToken => RemoveRedundantAsOperatorRefactoring.RefactorAsync(document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseStringLengthInsteadOfComparisonWithEmptyString:
{
CodeAction codeAction = CodeAction.Create(
"Use string.Length",
cancellationToken => UseStringLengthInsteadOfComparisonWithEmptyStringAsync(document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UnconstrainedTypeParameterCheckedForNull:
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(binaryExpression.Left, context.CancellationToken);
CodeAction codeAction = CodeAction.Create(
$"Use EqualityComparer<{typeSymbol.Name}>.Default",
cancellationToken => UnconstrainedTypeParameterCheckedForNullRefactoring.RefactorAsync(document, binaryExpression, typeSymbol, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.ValueTypeObjectIsNeverEqualToNull:
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(binaryExpression.Left, context.CancellationToken);
string title;
if (CSharpFacts.IsSimpleType(typeSymbol.SpecialType) ||
typeSymbol.ContainsMember <IMethodSymbol>(WellKnownMemberNames.EqualityOperatorName))
{
ExpressionSyntax expression = typeSymbol.GetDefaultValueSyntax(document.GetDefaultSyntaxOptions());
title = $"Replace 'null' with '{expression}'";
}
else
{
title = $"Use EqualityComparer<{SymbolDisplay.ToMinimalDisplayString(typeSymbol, semanticModel, binaryExpression.Right.SpanStart, SymbolDisplayFormats.DisplayName)}>.Default";
}
CodeAction codeAction = CodeAction.Create(
title,
cancellationToken => ValueTypeObjectIsNeverEqualToNullRefactoring.RefactorAsync(document, binaryExpression, typeSymbol, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.JoinStringExpressions:
{
CodeAction codeAction = CodeAction.Create(
"Join string expressions",
cancellationToken => JoinStringExpressionsRefactoring.RefactorAsync(document, binaryExpression, context.Span, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseExclusiveOrOperator:
{
CodeAction codeAction = CodeAction.Create(
"Use ^ operator",
cancellationToken => UseExclusiveOrOperatorRefactoring.RefactorAsync(document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.SimplifyBooleanExpression:
{
CodeAction codeAction = CodeAction.Create(
"Simplify boolean expression",
cancellationToken => SimplifyBooleanExpressionRefactoring.RefactorAsync(document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseShortCircuitingOperator:
{
SyntaxToken operatorToken = binaryExpression.OperatorToken;
SyntaxKind kind = binaryExpression.Kind();
SyntaxToken newToken = default;
if (kind == SyntaxKind.BitwiseAndExpression)
{
newToken = Token(operatorToken.LeadingTrivia, SyntaxKind.AmpersandAmpersandToken, operatorToken.TrailingTrivia);
}
else if (kind == SyntaxKind.BitwiseOrExpression)
{
newToken = Token(operatorToken.LeadingTrivia, SyntaxKind.BarBarToken, operatorToken.TrailingTrivia);
}
CodeAction codeAction = CodeAction.Create(
$"Use '{newToken.ToString()}' operator",
ct =>
{
BinaryExpressionSyntax newBinaryExpression = null;
if (kind == SyntaxKind.BitwiseAndExpression)
{
newBinaryExpression = LogicalAndExpression(binaryExpression.Left, newToken, binaryExpression.Right);
}
else if (kind == SyntaxKind.BitwiseOrExpression)
{
newBinaryExpression = LogicalOrExpression(binaryExpression.Left, newToken, binaryExpression.Right);
}
return(document.ReplaceNodeAsync(binaryExpression, newBinaryExpression, ct));
},
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UnnecessaryOperator:
{
CodeAction codeAction = CodeAction.Create(
"Use '==' operator",
ct =>
{
SyntaxToken operatorToken = binaryExpression.OperatorToken;
BinaryExpressionSyntax newBinaryExpression = EqualsExpression(
binaryExpression.Left,
Token(operatorToken.LeadingTrivia, SyntaxKind.EqualsEqualsToken, operatorToken.TrailingTrivia),
binaryExpression.Right);
return(document.ReplaceNodeAsync(binaryExpression, newBinaryExpression, ct));
},
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
}
}
}
public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
{
SyntaxNode root = await context.GetSyntaxRootAsync().ConfigureAwait(false);
if (!TryFindFirstAncestorOrSelf(root, context.Span, out BinaryExpressionSyntax binaryExpression))
{
return;
}
foreach (Diagnostic diagnostic in context.Diagnostics)
{
switch (diagnostic.Id)
{
case DiagnosticIdentifiers.SimplifyBooleanComparison:
{
CodeAction codeAction = CodeAction.Create(
"Simplify boolean comparison",
cancellationToken => SimplifyBooleanComparisonRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.CallAnyInsteadOfCount:
{
CodeAction codeAction = CodeAction.Create(
"Call 'Any' instead of 'Count'",
cancellationToken => CallAnyInsteadOfCountRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.AvoidNullLiteralExpressionOnLeftSideOfBinaryExpression:
{
CodeAction codeAction = CodeAction.Create(
$"Swap '{binaryExpression.Left}' and '{binaryExpression.Right}'",
cancellationToken => SwapExpressionsInBinaryExpressionRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseStringIsNullOrEmptyMethod:
{
CodeAction codeAction = CodeAction.Create(
"Use 'string.IsNullOrEmpty' method",
cancellationToken => UseStringIsNullOrEmptyMethodRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.SimplifyCoalesceExpression:
{
ExpressionSyntax expression = binaryExpression.Left;
if (expression == null ||
!context.Span.Contains(expression.Span))
{
expression = binaryExpression.Right;
}
CodeAction codeAction = CodeAction.Create(
"Simplify coalesce expression",
cancellationToken => SimplifyCoalesceExpressionRefactoring.RefactorAsync(context.Document, binaryExpression, expression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.RemoveRedundantAsOperator:
{
CodeAction codeAction = CodeAction.Create(
"Remove redundant 'as' operator",
cancellationToken => RemoveRedundantAsOperatorRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseStringLengthInsteadOfComparisonWithEmptyString:
{
CodeAction codeAction = CodeAction.Create(
"Use string.Length",
cancellationToken => UseStringLengthInsteadOfComparisonWithEmptyStringRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UnconstrainedTypeParameterCheckedForNull:
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(binaryExpression.Left, context.CancellationToken);
CodeAction codeAction = CodeAction.Create(
$"Use EqualityComparer<{typeSymbol.Name}>.Default",
cancellationToken => UnconstrainedTypeParameterCheckedForNullRefactoring.RefactorAsync(context.Document, binaryExpression, typeSymbol, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.ValueTypeObjectIsNeverEqualToNull:
{
SemanticModel semanticModel = await context.GetSemanticModelAsync().ConfigureAwait(false);
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(binaryExpression.Left, context.CancellationToken);
string title = null;
if (CSharpFacts.IsSimpleType(typeSymbol.SpecialType) ||
typeSymbol.ContainsMember <IMethodSymbol>(WellKnownMemberNames.EqualityOperatorName))
{
ExpressionSyntax expression = typeSymbol.GetDefaultValueSyntax(semanticModel, binaryExpression.Right.SpanStart);
title = $"Replace 'null' with '{expression}'";
}
else
{
title = $"Use EqualityComparer<{SymbolDisplay.ToMinimalDisplayString(typeSymbol, semanticModel, binaryExpression.Right.SpanStart, SymbolDisplayFormats.Default)}>.Default";
}
CodeAction codeAction = CodeAction.Create(
title,
cancellationToken => ValueTypeObjectIsNeverEqualToNullRefactoring.RefactorAsync(context.Document, binaryExpression, typeSymbol, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.JoinStringExpressions:
{
CodeAction codeAction = CodeAction.Create(
"Join string expressions",
cancellationToken => JoinStringExpressionsRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseExclusiveOrOperator:
{
CodeAction codeAction = CodeAction.Create(
"Use ^ operator",
cancellationToken => UseExclusiveOrOperatorRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.SimplifyBooleanExpression:
{
CodeAction codeAction = CodeAction.Create(
"Simplify boolean expression",
cancellationToken => SimplifyBooleanExpressionRefactoring.RefactorAsync(context.Document, binaryExpression, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.ExpressionIsAlwaysEqualToTrueOrFalse:
{
LiteralExpressionSyntax newNode = BooleanLiteralExpression(binaryExpression.IsKind(SyntaxKind.GreaterThanOrEqualExpression, SyntaxKind.LessThanOrEqualExpression));
CodeAction codeAction = CodeAction.Create(
$"Replace expression with '{newNode}'",
cancellationToken => context.Document.ReplaceNodeAsync(binaryExpression, newNode.WithTriviaFrom(binaryExpression), cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
}
}
}
public static void ComputeRefactoring(
RefactoringContext context,
SwitchStatementSyntax switchStatement,
SemanticModel semanticModel)
{
ExpressionSyntax expression = switchStatement.Expression;
if (expression?.IsMissing != false)
{
return;
}
SyntaxList <SwitchSectionSyntax> sections = switchStatement.Sections;
ISymbol symbol = semanticModel.GetSymbol(expression, context.CancellationToken);
if (symbol?.IsErrorType() != false)
{
return;
}
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(expression, context.CancellationToken);
if (typeSymbol?.TypeKind != TypeKind.Enum)
{
return;
}
if (!typeSymbol.ContainsMember <IFieldSymbol>())
{
return;
}
if (sections.Any() && !ContainsOnlyDefaultSection(sections))
{
if (context.Span.IsEmptyAndContainedInSpan(switchStatement.SwitchKeyword))
{
ImmutableArray <ISymbol> members = typeSymbol.GetMembers();
if (members.Length == 0)
{
return;
}
var fieldsToValue = new Dictionary <object, IFieldSymbol>(members.Length);
foreach (ISymbol member in members)
{
if (member.Kind == SymbolKind.Field)
{
var fieldSymbol = (IFieldSymbol)member;
if (fieldSymbol.HasConstantValue)
{
object constantValue = fieldSymbol.ConstantValue;
if (!fieldsToValue.ContainsKey(constantValue))
{
fieldsToValue.Add(constantValue, fieldSymbol);
}
}
}
}
foreach (SwitchSectionSyntax section in sections)
{
foreach (SwitchLabelSyntax label in section.Labels)
{
if (label.IsKind(SyntaxKind.CaseSwitchLabel))
{
var caseLabel = (CaseSwitchLabelSyntax)label;
ExpressionSyntax value = caseLabel.Value.WalkDownParentheses();
if (value?.IsMissing == false)
{
Optional <object> optional = semanticModel.GetConstantValue(value, context.CancellationToken);
if (optional.HasValue &&
fieldsToValue.Remove(optional.Value) &&
fieldsToValue.Count == 0)
{
return;
}
}
}
}
}
Document document = context.Document;
context.RegisterRefactoring(
Title,
ct => AddCasesAsync(document, switchStatement, fieldsToValue.Select(f => f.Value), ct),
RefactoringIdentifiers.AddMissingCases);
}
}
else if (context.IsRefactoringEnabled(RefactoringIdentifiers.AddMissingCases))
{
Document document = context.Document;
context.RegisterRefactoring(
Title,
ct => AddCasesAsync(document, switchStatement, semanticModel, ct),
RefactoringIdentifiers.AddMissingCases);
}
}