File: src\Analyzers\CSharp\CodeFixes\UsePatternMatching\CSharpUseNotPatternCodeFixProvider.cs
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Project: src\src\Features\CSharp\Portable\Microsoft.CodeAnalysis.CSharp.Features.csproj (Microsoft.CodeAnalysis.CSharp.Features)
// 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;
using System.Collections.Immutable;
using System.Composition;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp.CodeGeneration;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.Shared.Extensions;
 
namespace Microsoft.CodeAnalysis.CSharp.UsePatternMatching;
 
[ExportCodeFixProvider(LanguageNames.CSharp, Name = PredefinedCodeFixProviderNames.UseNotPattern), Shared]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal sealed class CSharpUseNotPatternCodeFixProvider() : SyntaxEditorBasedCodeFixProvider
{
    public override ImmutableArray<string> FixableDiagnosticIds
        => [IDEDiagnosticIds.UseNotPatternDiagnosticId];
 
    public override Task RegisterCodeFixesAsync(CodeFixContext context)
    {
        RegisterCodeFix(context, CSharpAnalyzersResources.Use_pattern_matching, nameof(CSharpAnalyzersResources.Use_pattern_matching));
        return Task.CompletedTask;
    }
 
    protected override async Task FixAllAsync(
        Document document, ImmutableArray<Diagnostic> diagnostics,
        SyntaxEditor editor, CancellationToken cancellationToken)
    {
        var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
        foreach (var diagnostic in diagnostics)
        {
            cancellationToken.ThrowIfCancellationRequested();
            ProcessDiagnostic(semanticModel, editor, diagnostic, cancellationToken);
        }
    }
 
    private static void ProcessDiagnostic(
        SemanticModel semanticModel,
        SyntaxEditor editor,
        Diagnostic diagnostic,
        CancellationToken cancellationToken)
    {
        var notExpressionLocation = diagnostic.AdditionalLocations[0];
 
        var notExpression = (PrefixUnaryExpressionSyntax)notExpressionLocation.FindNode(getInnermostNodeForTie: true, cancellationToken);
        var parenthesizedExpression = (ParenthesizedExpressionSyntax)notExpression.Operand;
 
        var negated = editor.Generator.Negate(
            CSharpSyntaxGeneratorInternal.Instance,
            parenthesizedExpression.Expression,
            semanticModel,
            cancellationToken);
 
        editor.ReplaceNode(
            notExpression,
            negated.WithPrependedLeadingTrivia(notExpression.GetLeadingTrivia())
                   .WithAppendedTrailingTrivia(notExpression.GetTrailingTrivia()));
    }
}