private static void CheckConditionalExpression(SyntaxNodeAnalysisContext c)
{
var conditional = (ConditionalExpressionSyntax)c.Node;
var condition = TernaryOperatorPointless.RemoveParentheses(conditional.Condition);
var whenTrue = TernaryOperatorPointless.RemoveParentheses(conditional.WhenTrue);
var whenFalse = TernaryOperatorPointless.RemoveParentheses(conditional.WhenFalse);
if (EquivalenceChecker.AreEquivalent(whenTrue, whenFalse))
{
/// handled by S2758, <see cref="TernaryOperatorPointless"/>
return;
}
ExpressionSyntax comparedToNull;
bool comparedIsNullInTrue;
if (!TryGetExpressionComparedToNull(condition, out comparedToNull, out comparedIsNullInTrue) ||
!ExpressionCanBeNull(comparedToNull, c.SemanticModel))
{
// expression not compared to null, or can't be null
return;
}
if (CanExpressionBeNullCoalescing(whenTrue, whenFalse, comparedToNull, comparedIsNullInTrue, c.SemanticModel))
{
c.ReportDiagnostic(Diagnostic.Create(Rule, conditional.GetLocation(), "??"));
}
}
public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
{
var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
var diagnostic = context.Diagnostics.First();
var diagnosticSpan = diagnostic.Location.SourceSpan;
var conditional = root.FindNode(diagnosticSpan, getInnermostNodeForTie: true) as ConditionalExpressionSyntax;
if (conditional == null)
{
return;
}
context.RegisterCodeFix(
CodeAction.Create(
Title,
c =>
{
var newRoot = root.ReplaceNode(
conditional,
TernaryOperatorPointless.RemoveParentheses(conditional.WhenTrue)
.WithAdditionalAnnotations(Formatter.Annotation));
return(Task.FromResult(context.Document.WithSyntaxRoot(newRoot)));
}),
context.Diagnostics);
}
private static bool CanBeSimplified(StatementSyntax statement1, StatementSyntax statement2,
ExpressionSyntax comparedToNull, bool comparedIsNullInTrue, SemanticModel semanticModel, out bool isNullCoalescing)
{
isNullCoalescing = false;
var return1 = statement1 as ReturnStatementSyntax;
var return2 = statement2 as ReturnStatementSyntax;
if (return1 != null && return2 != null)
{
var retExpr1 = TernaryOperatorPointless.RemoveParentheses(return1.Expression);
var retExpr2 = TernaryOperatorPointless.RemoveParentheses(return2.Expression);
if (!AreTypesCompatible(return1.Expression, return2.Expression, semanticModel))
{
return(false);
}
if (comparedToNull != null &&
CanExpressionBeNullCoalescing(retExpr1, retExpr2, comparedToNull, comparedIsNullInTrue, semanticModel))
{
isNullCoalescing = true;
}
return(true);
}
var expressionStatement1 = statement1 as ExpressionStatementSyntax;
var expressionStatement2 = statement2 as ExpressionStatementSyntax;
if (expressionStatement1 == null || expressionStatement2 == null)
{
return(false);
}
var expression1 = TernaryOperatorPointless.RemoveParentheses(expressionStatement1.Expression);
var expression2 = TernaryOperatorPointless.RemoveParentheses(expressionStatement2.Expression);
if (AreCandidateAssignments(expression1, expression2, comparedToNull, comparedIsNullInTrue,
semanticModel, out isNullCoalescing))
{
return(true);
}
if (comparedToNull != null &&
CanExpressionBeNullCoalescing(expression1, expression2, comparedToNull, comparedIsNullInTrue, semanticModel))
{
isNullCoalescing = true;
return(true);
}
if (AreCandidateInvocationsForTernary(expression1, expression2, semanticModel))
{
return(true);
}
return(false);
}
public sealed override async Task RegisterCodeFixesAsync(CodeFixContext context)
{
var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
var diagnostic = context.Diagnostics.First();
var diagnosticSpan = diagnostic.Location.SourceSpan;
var syntax = root.FindNode(diagnosticSpan);
var semanticModel = await context.Document.GetSemanticModelAsync(context.CancellationToken).ConfigureAwait(false);
var conditional = syntax as ConditionalExpressionSyntax;
if (conditional != null)
{
var condition = TernaryOperatorPointless.RemoveParentheses(conditional.Condition);
var whenTrue = TernaryOperatorPointless.RemoveParentheses(conditional.WhenTrue);
var whenFalse = TernaryOperatorPointless.RemoveParentheses(conditional.WhenFalse);
ExpressionSyntax compared;
bool comparedIsNullInTrue;
ConditionalSimplification.TryGetExpressionComparedToNull(condition, out compared, out comparedIsNullInTrue);
var annotation = new SyntaxAnnotation();
var coalescing = GetNullCoalescing(whenTrue, whenFalse, compared, semanticModel, annotation);
context.RegisterCodeFix(
GetActionToExecute(context, root, conditional, coalescing, annotation),
context.Diagnostics);
}
var ifStatement = syntax as IfStatementSyntax;
if (ifStatement != null)
{
var whenTrue = ConditionalSimplification.ExtractSingleStatement(ifStatement.Statement);
var whenFalse = ConditionalSimplification.ExtractSingleStatement(ifStatement.Else.Statement);
ExpressionSyntax compared;
bool comparedIsNullInTrue;
ConditionalSimplification.TryGetExpressionComparedToNull(ifStatement.Condition, out compared, out comparedIsNullInTrue);
var isNullCoalescing = bool.Parse(diagnostic.Properties[ConditionalSimplification.IsNullCoalescingKey]);
var annotation = new SyntaxAnnotation();
var simplified = GetSimplified(whenTrue, whenFalse, ifStatement.Condition, compared, isNullCoalescing, semanticModel, annotation);
context.RegisterCodeFix(
GetActionToExecute(context, root, ifStatement, simplified, annotation),
context.Diagnostics);
}
}
private static StatementSyntax GetSimplified(StatementSyntax statement1, StatementSyntax statement2,
ExpressionSyntax condition, ExpressionSyntax compared, bool isNullCoalescing, SemanticModel semanticModel,
SyntaxAnnotation annotation)
{
var return1 = statement1 as ReturnStatementSyntax;
var return2 = statement2 as ReturnStatementSyntax;
if (return1 != null && return2 != null)
{
var retExpr1 = TernaryOperatorPointless.RemoveParentheses(return1.Expression);
var retExpr2 = TernaryOperatorPointless.RemoveParentheses(return2.Expression);
var createdExpression = isNullCoalescing
? GetNullCoalescing(retExpr1, retExpr2, compared, semanticModel, annotation)
: SyntaxFactory.ConditionalExpression(
condition,
return1.Expression,
return2.Expression)
.WithAdditionalAnnotations(annotation);
return(SyntaxFactory.ReturnStatement(createdExpression));
}
var expressionStatement1 = statement1 as ExpressionStatementSyntax;
var expressionStatement2 = statement2 as ExpressionStatementSyntax;
var expression1 = TernaryOperatorPointless.RemoveParentheses(expressionStatement1.Expression);
var expression2 = TernaryOperatorPointless.RemoveParentheses(expressionStatement2.Expression);
var assignment = GetSimplifiedAssignment(expression1, expression2, condition, compared, isNullCoalescing, semanticModel, annotation);
if (assignment != null)
{
return(SyntaxFactory.ExpressionStatement(assignment));
}
var expression = GetSimplificationFromInvocations(expression1, expression2, condition, compared, isNullCoalescing, semanticModel, annotation);
if (expression != null)
{
return(SyntaxFactory.ExpressionStatement(expression));
}
return(null);
}