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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.CodeActions;
using Microsoft.CodeAnalysis.CodeRefactorings;
using Microsoft.CodeAnalysis.CodeStyle;
using Microsoft.CodeAnalysis.CSharp.CodeFixes.UseExpressionBodyForLambda;
using Microsoft.CodeAnalysis.CSharp.Extensions;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Diagnostics;
using Microsoft.CodeAnalysis.Shared.Collections;
using Microsoft.CodeAnalysis.Shared.Extensions;
using Microsoft.CodeAnalysis.Text;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis.CSharp.UseExpressionBodyForLambda;
[ExportCodeRefactoringProvider(LanguageNames.CSharp, Name = PredefinedCodeRefactoringProviderNames.UseExpressionBodyForLambda), Shared]
internal sealed class UseExpressionBodyForLambdaCodeRefactoringProvider : CodeRefactoringProvider
{
[ImportingConstructor]
[SuppressMessage("RoslynDiagnosticsReliability", "RS0033:Importing constructor should be [Obsolete]", Justification = "Used in test code: https://github.com/dotnet/roslyn/issues/42814")]
public UseExpressionBodyForLambdaCodeRefactoringProvider()
{
}
public override async Task ComputeRefactoringsAsync(CodeRefactoringContext context)
{
var document = context.Document;
var cancellationToken = context.CancellationToken;
var optionProvider = await document.GetAnalyzerOptionsProviderAsync(cancellationToken).ConfigureAwait(false);
var optionValue = UseExpressionBodyForLambdaHelpers.GetCodeStyleOption(optionProvider);
var severity = UseExpressionBodyForLambdaHelpers.GetOptionSeverity(optionValue);
switch (severity)
{
case ReportDiagnostic.Suppress:
case ReportDiagnostic.Hidden:
// if the severity is Hidden that's equivalent to 'refactoring only', so we want
// to try to compute the refactoring here.
//
// If the severity is 'suppress', that means the user doesn't want the actual
// analyzer to run here. However, we can still check to see if we could offer
// the feature here as a refactoring.
await ComputeRefactoringsAsync(context, optionValue.Value, analyzerActive: false).ConfigureAwait(false);
return;
case ReportDiagnostic.Error:
case ReportDiagnostic.Warn:
case ReportDiagnostic.Info:
// User has this option set at a level where we want it checked by the
// DiagnosticAnalyser and not the CodeRefactoringProvider. However, we still
// want to check if we want to offer the *reverse* refactoring here in this
// single location.
//
// For example, say this is the "use expression body" feature. If the user says
// they always prefer expression-bodies (with warning level), then we want the
// analyzer to always be checking for that. However, we still want to offer the
// refactoring to flip their code to use a block body here, just in case that
// was something they wanted to do as a one off (i.e. before adding new
// statements.
//
// TODO(cyrusn): Should we only do this for warn/info? Argument could be made
// that we shouldn't even offer to refactor in the reverse direction if it will
// just cause an error. That said, maybe this is just an intermediary step, and
// we shouldn't really be blocking the user from making it.
await ComputeRefactoringsAsync(context, optionValue.Value, analyzerActive: true).ConfigureAwait(false);
return;
}
}
private static async Task ComputeRefactoringsAsync(
CodeRefactoringContext context, ExpressionBodyPreference option, bool analyzerActive)
{
var document = context.Document;
var span = context.Span;
var cancellationToken = context.CancellationToken;
var computationTask = analyzerActive
? ComputeOpposingRefactoringsWhenAnalyzerActiveAsync(document, span, option, cancellationToken)
: ComputeAllRefactoringsWhenAnalyzerInactiveAsync(document, span, cancellationToken);
var codeActions = await computationTask.ConfigureAwait(false);
context.RegisterRefactorings(codeActions);
}
private static async Task<ImmutableArray<CodeAction>> ComputeOpposingRefactoringsWhenAnalyzerActiveAsync(
Document document, TextSpan span, ExpressionBodyPreference option, CancellationToken cancellationToken)
{
if (option == ExpressionBodyPreference.Never)
{
// the user wants block-bodies (and the analyzer will be trying to enforce that). So
// the reverse of this is that we want to offer the refactoring to convert a
// block-body to an expression-body whenever possible.
return await ComputeRefactoringsAsync(
document, span, ExpressionBodyPreference.WhenPossible, cancellationToken).ConfigureAwait(false);
}
else if (option == ExpressionBodyPreference.WhenPossible)
{
// the user likes expression-bodies whenever possible, and the analyzer will be
// trying to enforce that. So the reverse of this is that we want to offer the
// refactoring to convert an expression-body to a block-body whenever possible.
return await ComputeRefactoringsAsync(
document, span, ExpressionBodyPreference.Never, cancellationToken).ConfigureAwait(false);
}
else if (option == ExpressionBodyPreference.WhenOnSingleLine)
{
// the user likes expression-bodies *if* the body would be on a single line. this
// means if we hit an block-body with an expression on a single line, then the
// analyzer will handle it for us.
// So we need to handle the cases of either hitting an expression-body and wanting
// to convert it to a block-body *or* hitting an block-body over *multiple* lines and
// wanting to offer to convert to an expression-body.
// Always offer to convert an expression to a block since the analyzer will never
// offer that. For this option setting.
var useBlockRefactorings = await ComputeRefactoringsAsync(
document, span, ExpressionBodyPreference.Never, cancellationToken).ConfigureAwait(false);
var whenOnSingleLineRefactorings = await ComputeRefactoringsAsync(
document, span, ExpressionBodyPreference.WhenOnSingleLine, cancellationToken).ConfigureAwait(false);
if (whenOnSingleLineRefactorings.Length > 0)
{
// this block lambda would be converted to an expression lambda based on the
// analyzer alone. So we don't want to offer that as a refactoring ourselves.
return useBlockRefactorings;
}
// The lambda block statement wasn't on a single line. So the analyzer would
// not offer to convert it to an expression body. So we should can offer that
// as a refactoring if possible.
var whenPossibleRefactorings = await ComputeRefactoringsAsync(
document, span, ExpressionBodyPreference.WhenPossible, cancellationToken).ConfigureAwait(false);
return useBlockRefactorings.AddRange(whenPossibleRefactorings);
}
else
{
throw ExceptionUtilities.UnexpectedValue(option);
}
}
private static async Task<ImmutableArray<CodeAction>> ComputeAllRefactoringsWhenAnalyzerInactiveAsync(
Document document, TextSpan span, CancellationToken cancellationToken)
{
// If the analyzer is inactive, then we want to offer refactorings in any viable
// direction. So we want to offer to convert expression-bodies to block-bodies, and
// vice-versa if applicable.
var toExpressionBodyRefactorings = await ComputeRefactoringsAsync(
document, span, ExpressionBodyPreference.WhenPossible, cancellationToken).ConfigureAwait(false);
var toBlockBodyRefactorings = await ComputeRefactoringsAsync(
document, span, ExpressionBodyPreference.Never, cancellationToken).ConfigureAwait(false);
return toExpressionBodyRefactorings.AddRange(toBlockBodyRefactorings);
}
private static async Task<ImmutableArray<CodeAction>> ComputeRefactoringsAsync(
Document document, TextSpan span, ExpressionBodyPreference option, CancellationToken cancellationToken)
{
var lambdaNode = await document.TryGetRelevantNodeAsync<LambdaExpressionSyntax>(span, cancellationToken).ConfigureAwait(false);
if (lambdaNode == null)
return [];
var root = await document.GetRequiredSyntaxRootAsync(cancellationToken).ConfigureAwait(false);
using var result = TemporaryArray<CodeAction>.Empty;
if (UseExpressionBodyForLambdaHelpers.CanOfferUseExpressionBody(option, lambdaNode, root.GetLanguageVersion(), cancellationToken))
{
var title = UseExpressionBodyForLambdaHelpers.UseExpressionBodyTitle.ToString();
result.Add(CodeAction.Create(
title,
cancellationToken => UpdateDocumentAsync(document, root, lambdaNode, cancellationToken),
title));
}
var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
if (UseExpressionBodyForLambdaHelpers.CanOfferUseBlockBody(semanticModel, option, lambdaNode, cancellationToken))
{
var title = UseExpressionBodyForLambdaHelpers.UseBlockBodyTitle.ToString();
result.Add(CodeAction.Create(
title,
cancellationToken => UpdateDocumentAsync(document, root, lambdaNode, cancellationToken),
title));
}
return result.ToImmutableAndClear();
}
private static async Task<Document> UpdateDocumentAsync(
Document document, SyntaxNode root, LambdaExpressionSyntax declaration, CancellationToken cancellationToken)
{
var semanticModel = await document.GetRequiredSemanticModelAsync(cancellationToken).ConfigureAwait(false);
// We're only replacing a single declaration in the refactoring. So pass 'declaration'
// as both the 'original' and 'current' declaration.
var updatedDeclaration = UseExpressionBodyForLambdaCodeActionHelpers.Update(semanticModel, declaration, declaration, cancellationToken);
var newRoot = root.ReplaceNode(declaration, updatedDeclaration);
return document.WithSyntaxRoot(newRoot);
}
}
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