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UseConditionalAccessCodeFixProvider.cs
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UseConditionalAccessCodeFixProvider.cs
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// Copyright (c) .NET Foundation and Contributors. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System.Collections.Generic;
using System.Collections.Immutable;
using System.Composition;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CodeActions;
using Microsoft.CodeAnalysis.CodeFixes;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Text;
using Roslynator.CodeFixes;
using Roslynator.CSharp.Analysis;
using Roslynator.CSharp.Syntax;
using Roslynator.Text;
namespace Roslynator.CSharp.CodeFixes;
[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(UseConditionalAccessCodeFixProvider))]
[Shared]
public sealed class UseConditionalAccessCodeFixProvider : BaseCodeFixProvider
{
private const string Title = "Use conditional access";
public override ImmutableArray<string> FixableDiagnosticIds
{
get { return ImmutableArray.Create(DiagnosticIdentifiers.UseConditionalAccess); }
}
public override async Task RegisterCodeFixesAsync(CodeFixContext context)
{
SyntaxNode root = await context.GetSyntaxRootAsync().ConfigureAwait(false);
if (!TryFindFirstAncestorOrSelf(
root,
context.Span,
out SyntaxNode node,
predicate: f => f.IsKind(
SyntaxKind.LogicalAndExpression,
SyntaxKind.LogicalOrExpression,
SyntaxKind.IfStatement)))
{
return;
}
switch (node.Kind())
{
case SyntaxKind.LogicalAndExpression:
case SyntaxKind.LogicalOrExpression:
{
CodeAction codeAction = CodeAction.Create(
Title,
ct => UseConditionalAccessAsync(context.Document, (BinaryExpressionSyntax)node, ct),
GetEquivalenceKey(DiagnosticIdentifiers.UseConditionalAccess));
context.RegisterCodeFix(codeAction, context.Diagnostics);
break;
}
case SyntaxKind.IfStatement:
{
CodeAction codeAction = CodeAction.Create(
Title,
ct => UseConditionalAccessAsync(context.Document, (IfStatementSyntax)node, ct),
GetEquivalenceKey(DiagnosticIdentifiers.UseConditionalAccess));
context.RegisterCodeFix(codeAction, context.Diagnostics);
break;
}
}
}
private static async Task<Document> UseConditionalAccessAsync(
Document document,
BinaryExpressionSyntax binaryExpression,
CancellationToken cancellationToken)
{
SemanticModel semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
SyntaxKind kind = binaryExpression.Kind();
(ExpressionSyntax left, ExpressionSyntax right) = UseConditionalAccessAnalyzer.GetFixableExpressions(binaryExpression, kind, semanticModel, cancellationToken);
NullCheckStyles allowedStyles = (kind == SyntaxKind.LogicalAndExpression)
? (NullCheckStyles.NotEqualsToNull | NullCheckStyles.IsNotNull)
: (NullCheckStyles.EqualsToNull | NullCheckStyles.IsNull);
NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(left, semanticModel, allowedStyles: allowedStyles, cancellationToken: cancellationToken);
ExpressionSyntax expression = nullCheck.Expression;
bool isNullable = semanticModel.GetTypeSymbol(expression, cancellationToken).IsNullableType();
ExpressionSyntax expression2 = UseConditionalAccessAnalyzer.FindExpressionThatCanBeConditionallyAccessed(
expression,
right,
isNullable: isNullable,
semanticModel,
cancellationToken);
var builder = new SyntaxNodeTextBuilder(binaryExpression, StringBuilderCache.GetInstance(binaryExpression.FullSpan.Length));
builder.Append(TextSpan.FromBounds(binaryExpression.FullSpan.Start, left.SpanStart));
int parenDiff = GetParenTokenDiff();
if (parenDiff > 0)
builder.Append('(', parenDiff);
builder.AppendSpan(expression);
builder.Append("?");
builder.Append(TextSpan.FromBounds(expression2.Span.End, right.Span.End));
switch (right.Kind())
{
case SyntaxKind.LogicalOrExpression:
case SyntaxKind.LogicalAndExpression:
case SyntaxKind.BitwiseOrExpression:
case SyntaxKind.BitwiseAndExpression:
case SyntaxKind.ExclusiveOrExpression:
case SyntaxKind.EqualsExpression:
case SyntaxKind.NotEqualsExpression:
case SyntaxKind.LessThanExpression:
case SyntaxKind.LessThanOrEqualExpression:
case SyntaxKind.GreaterThanExpression:
case SyntaxKind.GreaterThanOrEqualExpression:
case SyntaxKind.IsExpression:
case SyntaxKind.AsExpression:
case SyntaxKind.IsPatternExpression:
{
break;
}
case SyntaxKind.LogicalNotExpression:
{
builder.Append((kind == SyntaxKind.LogicalAndExpression) ? " == false" : " != true");
break;
}
default:
{
builder.Append((kind == SyntaxKind.LogicalAndExpression) ? " == true" : " != false");
break;
}
}
if (parenDiff < 0)
builder.Append(')', -parenDiff);
builder.Append(TextSpan.FromBounds(right.Span.End, binaryExpression.FullSpan.End));
string text = StringBuilderCache.GetStringAndFree(builder.StringBuilder);
ParenthesizedExpressionSyntax newNode = SyntaxFactory.ParseExpression(text)
.WithFormatterAnnotation()
.Parenthesize();
return await document.ReplaceNodeAsync(binaryExpression, newNode, cancellationToken).ConfigureAwait(false);
int GetParenTokenDiff()
{
int count = 0;
foreach (SyntaxToken token in binaryExpression.DescendantTokens(TextSpan.FromBounds(left.SpanStart, expression2.Span.End)))
{
SyntaxKind tokenKind = token.Kind();
if (tokenKind == SyntaxKind.OpenParenToken)
{
if (token.IsParentKind(SyntaxKind.ParenthesizedExpression))
count++;
}
else if (tokenKind == SyntaxKind.CloseParenToken)
{
if (token.IsParentKind(SyntaxKind.ParenthesizedExpression))
count--;
}
}
return count;
}
}
private static async Task<Document> UseConditionalAccessAsync(
Document document,
IfStatementSyntax ifStatement,
CancellationToken cancellationToken)
{
var statement = (ExpressionStatementSyntax)ifStatement.SingleNonBlockStatementOrDefault();
StatementSyntax newStatement = statement;
NullCheckExpressionInfo nullCheck = SyntaxInfo.NullCheckExpressionInfo(ifStatement.Condition, NullCheckStyles.NotEqualsToNull | NullCheckStyles.IsNotNull);
SimpleMemberInvocationStatementInfo invocationInfo = SyntaxInfo.SimpleMemberInvocationStatementInfo(statement);
ExpressionSyntax expression = invocationInfo.Expression;
SemanticModel semanticModel = await document.GetSemanticModelAsync(cancellationToken).ConfigureAwait(false);
if (semanticModel.GetTypeSymbol(nullCheck.Expression, cancellationToken).IsNullableType())
{
var memberAccess = (MemberAccessExpressionSyntax)invocationInfo.Expression;
newStatement = statement.ReplaceNode(memberAccess, memberAccess.Expression.WithTrailingTrivia(memberAccess.GetTrailingTrivia()));
expression = memberAccess.Expression;
}
int insertIndex = expression.Span.End - statement.FullSpan.Start;
newStatement = SyntaxFactory.ParseStatement(newStatement.ToFullString().Insert(insertIndex, "?"));
IEnumerable<SyntaxTrivia> leading = ifStatement.DescendantTrivia(TextSpan.FromBounds(ifStatement.SpanStart, statement.SpanStart));
newStatement = (leading.All(f => f.IsWhitespaceOrEndOfLineTrivia()))
? newStatement.WithLeadingTrivia(ifStatement.GetLeadingTrivia())
: newStatement.WithLeadingTrivia(ifStatement.GetLeadingTrivia().Concat(leading));
IEnumerable<SyntaxTrivia> trailing = ifStatement.DescendantTrivia(TextSpan.FromBounds(statement.Span.End, ifStatement.Span.End));
newStatement = (leading.All(f => f.IsWhitespaceOrEndOfLineTrivia()))
? newStatement.WithTrailingTrivia(ifStatement.GetTrailingTrivia())
: newStatement.WithTrailingTrivia(trailing.Concat(ifStatement.GetTrailingTrivia()));
return await document.ReplaceNodeAsync(ifStatement, newStatement, cancellationToken).ConfigureAwait(false);
}
}