public static void AnalyzeConditionalExpression(SyntaxNodeAnalysisContext context)
{
if (context.Node.SpanContainsDirectives())
{
return;
}
var conditionalExpression = (ConditionalExpressionSyntax)context.Node;
if (!ConditionalExpressionInfo.TryCreate(conditionalExpression, out ConditionalExpressionInfo conditionalExpressionInfo))
{
return;
}
SemanticModel semanticModel = context.SemanticModel;
CancellationToken cancellationToken = context.CancellationToken;
if (!NullCheckExpression.TryCreate(conditionalExpressionInfo.Condition, semanticModel, out NullCheckExpression nullCheck, cancellationToken))
{
return;
}
ExpressionSyntax whenNotNull = (nullCheck.IsCheckingNotNull) ? conditionalExpressionInfo.WhenTrue : conditionalExpressionInfo.WhenFalse;
ExpressionSyntax whenNull = (nullCheck.IsCheckingNotNull) ? conditionalExpressionInfo.WhenFalse : conditionalExpressionInfo.WhenTrue;
if (SyntaxComparer.AreEquivalent(nullCheck.Expression, whenNotNull))
{
if (semanticModel
.GetTypeSymbol(nullCheck.Expression, cancellationToken)?
.IsReferenceTypeOrNullableType() == true)
{
context.ReportDiagnostic(
DiagnosticDescriptors.UseCoalesceExpressionInsteadOfConditionalExpression,
conditionalExpression);
}
}
else if (whenNotNull.IsKind(
SyntaxKind.SimpleMemberAccessExpression,
SyntaxKind.ElementAccessExpression,
SyntaxKind.ConditionalAccessExpression,
SyntaxKind.InvocationExpression))
{
ExpressionSyntax expression = UseConditionalAccessRefactoring.FindExpressionThatCanBeConditionallyAccessed(nullCheck.Expression, whenNotNull);
if (expression == null)
{
return;
}
ITypeSymbol typeSymbol = semanticModel.GetTypeSymbol(nullCheck.Expression, cancellationToken);
if (typeSymbol == null)
{
return;
}
if (typeSymbol.IsReferenceType)
{
Analyze(context, conditionalExpressionInfo, whenNull, whenNotNull, semanticModel, cancellationToken);
}
else if (typeSymbol.IsConstructedFrom(SpecialType.System_Nullable_T))
{
if (expression.IsParentKind(SyntaxKind.SimpleMemberAccessExpression))
{
var memberAccessExpression = (MemberAccessExpressionSyntax)expression.Parent;
if (!memberAccessExpression.IsParentKind(SyntaxKind.InvocationExpression) &&
(memberAccessExpression.Name as IdentifierNameSyntax)?.Identifier.ValueText == "Value")
{
if (memberAccessExpression == whenNotNull)
{
context.ReportDiagnostic(
DiagnosticDescriptors.UseCoalesceExpressionInsteadOfConditionalExpression,
conditionalExpression);
}
else
{
Analyze(context, conditionalExpressionInfo, whenNull, whenNotNull, semanticModel, cancellationToken);
}
}
}
}
}
}
public static async Task <Document> RefactorAsync(
Document document,
ConditionalExpressionSyntax conditionalExpression,
CancellationToken cancellationToken)
{
SemanticModel semanticModel = await document.GetSemanticModelAsync().ConfigureAwait(false);
ConditionalExpressionInfo.TryCreate(conditionalExpression, out ConditionalExpressionInfo conditionalExpressionInfo);
NullCheckExpression.TryCreate(conditionalExpressionInfo.Condition, semanticModel, out NullCheckExpression nullCheck, cancellationToken);
ExpressionSyntax whenNotNull = (nullCheck.IsCheckingNotNull) ? conditionalExpressionInfo.WhenTrue : conditionalExpressionInfo.WhenFalse;
ExpressionSyntax whenNull = (nullCheck.IsCheckingNotNull) ? conditionalExpressionInfo.WhenFalse : conditionalExpressionInfo.WhenTrue;
ExpressionSyntax expression = UseConditionalAccessRefactoring.FindExpressionThatCanBeConditionallyAccessed(nullCheck.Expression, whenNotNull);
bool coalesce = false;
ExpressionSyntax newNode = null;
if (SyntaxComparer.AreEquivalent(nullCheck.Expression, whenNotNull))
{
newNode = nullCheck.Expression;
coalesce = true;
}
else if (semanticModel
.GetTypeSymbol(nullCheck.Expression, cancellationToken)
.IsConstructedFrom(SpecialType.System_Nullable_T))
{
if (expression.IsParentKind(SyntaxKind.SimpleMemberAccessExpression))
{
var memberAccessExpression = (MemberAccessExpressionSyntax)expression.Parent;
if (!memberAccessExpression.IsParentKind(SyntaxKind.InvocationExpression) &&
(memberAccessExpression.Name as IdentifierNameSyntax)?.Identifier.ValueText == "Value")
{
if (memberAccessExpression == whenNotNull)
{
newNode = nullCheck.Expression;
coalesce = true;
}
else
{
newNode = ParseExpression($"{expression}?{whenNotNull.ToString().Substring(memberAccessExpression.Span.End - whenNotNull.SpanStart)}");
}
}
}
}
if (newNode == null)
{
newNode = ParseExpression(whenNotNull.ToString().Insert(expression.Span.End - whenNotNull.SpanStart, "?"));
}
if (coalesce || !semanticModel.GetTypeSymbol(whenNotNull, cancellationToken).IsReferenceType)
{
newNode = CoalesceExpression(newNode.Parenthesize(), whenNull.Parenthesize());
}
newNode = newNode
.WithTriviaFrom(conditionalExpression)
.Parenthesize();
return(await document.ReplaceNodeAsync(conditionalExpression, newNode, cancellationToken).ConfigureAwait(false));
}