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 (typeSymbol.IsPredefinedValueType() ||
typeSymbol.ExistsMethod(WellKnownMemberNames.EqualityOperatorName))
{
newNode = typeSymbol.ToDefaultValueSyntax(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;
}
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.UseAnyMethodInsteadOfCountMethod:
{
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 (typeSymbol.IsPredefinedValueType() ||
typeSymbol.ExistsMethod(WellKnownMemberNames.EqualityOperatorName))
{
ExpressionSyntax expression = typeSymbol.ToDefaultValueSyntax(semanticModel, binaryExpression.Right.SpanStart);
title = $"Replace 'null' with '{expression}'";
}
else
{
title = $"Use EqualityComparer<{SymbolDisplay.GetMinimalString(typeSymbol, semanticModel, binaryExpression.Right.SpanStart)}>.Default";
}
CodeAction codeAction = CodeAction.Create(
title,
cancellationToken => ValueTypeObjectIsNeverEqualToNullRefactoring.RefactorAsync(context.Document, binaryExpression, typeSymbol, cancellationToken),
GetEquivalenceKey(diagnostic));
context.RegisterCodeFix(codeAction, diagnostic);
break;
}
case DiagnosticIdentifiers.UseIsOperatorInsteadOfAsOperator:
{
CodeAction codeAction = CodeAction.Create(
"Use is operator",
cancellationToken => UseIsOperatorInsteadOfAsOperatorRefactoring.RefactorAsync(context.Document, binaryExpression, 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;
}
}
}
}
