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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System.Collections.Immutable;
using System.Composition;
using System.Diagnostics.CodeAnalysis;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.CSharp.Simplification.Simplifiers;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Simplification;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis.CSharp.RemoveUnnecessaryCast;
[ExportCodeFixProvider(LanguageNames.CSharp, Name = PredefinedCodeFixProviderNames.RemoveUnnecessaryCast), Shared]
[ExtensionOrder(After = PredefinedCodeFixProviderNames.ImplementInterface)]
[method: ImportingConstructor]
[method: SuppressMessage("RoslynDiagnosticsReliability", "RS0033:Importing constructor should be [Obsolete]", Justification = "Used in test code: https://github.com/dotnet/roslyn/issues/42814")]
internal sealed partial class CSharpRemoveUnnecessaryCastCodeFixProvider() : SyntaxEditorBasedCodeFixProvider
{
public sealed override ImmutableArray<string> FixableDiagnosticIds { get; } =
[IDEDiagnosticIds.RemoveUnnecessaryCastDiagnosticId];
public sealed override Task RegisterCodeFixesAsync(CodeFixContext context)
{
RegisterCodeFix(context, AnalyzersResources.Remove_Unnecessary_Cast, nameof(AnalyzersResources.Remove_Unnecessary_Cast));
return Task.CompletedTask;
}
protected override async Task FixAllAsync(
Document document, ImmutableArray<Diagnostic> diagnostics,
SyntaxEditor editor, CancellationToken cancellationToken)
{
var castNodes = diagnostics.SelectAsArray(
d => (ExpressionSyntax)d.AdditionalLocations[0].FindNode(getInnermostNodeForTie: true, cancellationToken));
await editor.ApplyExpressionLevelSemanticEditsAsync(
document, castNodes,
(semanticModel, castExpression) => CastSimplifier.IsUnnecessaryCast(castExpression, semanticModel, cancellationToken),
(_, currentRoot, castExpression) =>
{
var oldParent = castExpression.WalkUpParentheses();
var newParent = Recurse(oldParent);
return currentRoot.ReplaceNode(oldParent, newParent);
},
cancellationToken).ConfigureAwait(false);
}
private static ExpressionSyntax Recurse(ExpressionSyntax old)
{
if (old is ParenthesizedExpressionSyntax parenthesizedExpression)
{
// It's common in C# to have to write ((Goo)expr).Etc(). we don't just want to
// remove the cast and produce (expr).Etc(). So we mark all parent parenthesized
// expressions as worthy of simplification. The simplifier will remove these
// if possible, or leave them alone if not.
return parenthesizedExpression.ReplaceNode(parenthesizedExpression.Expression, Recurse(parenthesizedExpression.Expression))
.WithAdditionalAnnotations(Simplifier.Annotation);
}
else if (old is CastExpressionSyntax castExpression)
{
// parenthesize the uncasted value to help ensure any proper parsing. The excess
// parens will be removed if unnecessary.
return castExpression.Uncast().WithAdditionalAnnotations(Formatter.Annotation)
.Parenthesize();
}
else if (old is BinaryExpressionSyntax binaryExpression)
{
return binaryExpression.Left.WithTrailingTrivia(binaryExpression.GetTrailingTrivia())
.WithAdditionalAnnotations(Simplifier.Annotation);
}
else
{
throw ExceptionUtilities.UnexpectedValue(old);
}
}
}
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