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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;
using System.Collections.Immutable;
using System.Composition;
using System.Diagnostics;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Editing;
using Microsoft.CodeAnalysis.Formatting;
using Microsoft.CodeAnalysis.Host.Mef;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis.CSharp.ConvertSwitchStatementToExpression;
using Constants = ConvertSwitchStatementToExpressionConstants;
[ExportCodeFixProvider(LanguageNames.CSharp, Name = PredefinedCodeFixProviderNames.ConvertSwitchStatementToExpression), Shared]
[method: ImportingConstructor]
[method: Obsolete(MefConstruction.ImportingConstructorMessage, error: true)]
internal sealed partial class ConvertSwitchStatementToExpressionCodeFixProvider() : SyntaxEditorBasedCodeFixProvider
{
public override ImmutableArray<string> FixableDiagnosticIds
=> [IDEDiagnosticIds.ConvertSwitchStatementToExpressionDiagnosticId];
public override Task RegisterCodeFixesAsync(CodeFixContext context)
{
var switchLocation = context.Diagnostics.First().AdditionalLocations[0];
var switchStatement = (SwitchStatementSyntax)switchLocation.FindNode(getInnermostNodeForTie: true, context.CancellationToken);
if (switchStatement.ContainsDirectives)
{
// Avoid providing code fixes for switch statements containing directives
return Task.CompletedTask;
}
RegisterCodeFix(context, CSharpAnalyzersResources.Convert_switch_statement_to_expression, nameof(CSharpAnalyzersResources.Convert_switch_statement_to_expression));
return Task.CompletedTask;
}
protected override async Task FixAllAsync(
Document document, ImmutableArray<Diagnostic> diagnostics,
SyntaxEditor editor, CancellationToken cancellationToken)
{
using var _ = ArrayBuilder<TextSpan>.GetInstance(diagnostics.Length, out var spans);
foreach (var diagnostic in diagnostics)
{
cancellationToken.ThrowIfCancellationRequested();
var switchLocation = diagnostic.AdditionalLocations[0];
if (spans.Any((s, nodeSpan) => s.Contains(nodeSpan), switchLocation.SourceSpan))
{
// Skip nested switch expressions in case of a fix-all operation.
continue;
}
spans.Add(switchLocation.SourceSpan);
var properties = diagnostic.Properties;
var nodeToGenerate = (SyntaxKind)int.Parse(properties[Constants.NodeToGenerateKey]!);
var shouldRemoveNextStatement = bool.Parse(properties[Constants.ShouldRemoveNextStatementKey]!);
var declaratorToRemoveLocation = diagnostic.AdditionalLocations.ElementAtOrDefault(1);
var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
VariableDeclaratorSyntax? declaratorToRemoveNode = null;
ITypeSymbol? declaratorToRemoveType = null;
if (declaratorToRemoveLocation != null)
{
declaratorToRemoveNode = (VariableDeclaratorSyntax)declaratorToRemoveLocation.FindNode(getInnermostNodeForTie: true, cancellationToken);
declaratorToRemoveType = semanticModel.GetDeclaredSymbol(declaratorToRemoveNode, cancellationToken).GetSymbolType();
}
var switchStatement = (SwitchStatementSyntax)switchLocation.FindNode(getInnermostNodeForTie: true, cancellationToken);
var switchExpressionStatement = Rewriter.Rewrite(
switchStatement, semanticModel, declaratorToRemoveType, nodeToGenerate,
shouldMoveNextStatementToSwitchExpression: shouldRemoveNextStatement,
generateDeclaration: declaratorToRemoveLocation is not null,
cancellationToken);
if (declaratorToRemoveNode is not null)
{
editor.RemoveNode(declaratorToRemoveNode);
// If we are removing the declarator statement entirely, transfer its leading trivia to the
// expression-statement are converting to.
if (declaratorToRemoveNode.Parent is VariableDeclarationSyntax { Parent: LocalDeclarationStatementSyntax declStatement, Variables.Count: 1 })
switchExpressionStatement = switchExpressionStatement.WithPrependedLeadingTrivia(declStatement.GetLeadingTrivia());
}
editor.ReplaceNode(switchStatement, switchExpressionStatement.WithAdditionalAnnotations(Formatter.Annotation));
if (shouldRemoveNextStatement)
{
// Already morphed into the top-level switch expression.
var nextStatement = switchStatement.GetNextStatement();
Contract.ThrowIfNull(nextStatement);
Debug.Assert(nextStatement.Kind() is SyntaxKind.ThrowStatement or SyntaxKind.ReturnStatement);
editor.RemoveNode(nextStatement.IsParentKind(SyntaxKind.GlobalStatement) ? nextStatement.GetRequiredParent() : nextStatement);
}
}
}
}
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