protected sealed override async Task RegisterCodeFixesAsync(SyntaxNode root, CodeFixContext context)
{
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 = conditional.Condition.RemoveParentheses();
var whenTrue = conditional.WhenTrue.RemoveParentheses();
var whenFalse = conditional.WhenFalse.RemoveParentheses();
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, semanticModel, annotation, isNullCoalescing);
context.RegisterCodeFix(
GetActionToExecute(context, root, ifStatement, simplified, annotation),
context.Diagnostics);
}
}
private static SyntaxNode Simplify(Diagnostic diagnostic, SemanticModel semanticModel, SyntaxNode oldNode, out SyntaxAnnotation annotation)
{
ExpressionSyntax compared;
switch (oldNode)
{
case ConditionalExpressionSyntax conditional:
var condition = conditional.Condition.RemoveParentheses();
var whenTrue = conditional.WhenTrue.RemoveParentheses();
var whenFalse = conditional.WhenFalse.RemoveParentheses();
ConditionalSimplification.TryGetExpressionComparedToNull(condition, out compared, out _);
return(SimplifyCoalesceExpression(new ComparedContext(diagnostic, semanticModel, compared, out annotation), whenTrue, whenFalse));
case IfStatementSyntax ifStatement:
var ifPart = ConditionalSimplification.ExtractSingleStatement(ifStatement.Statement);
var elsePart = ConditionalSimplification.ExtractSingleStatement(ifStatement.Else?.Statement);
ConditionalSimplification.TryGetExpressionComparedToNull(ifStatement.Condition, out compared, out var _);
return(SimplifyIfStatement(new ComparedContext(diagnostic, semanticModel, compared, out annotation), ifPart, elsePart, ifStatement.Condition.RemoveParentheses()));
case AssignmentExpressionSyntax assignment:
var context = new ComparedContext(diagnostic, semanticModel, null, out annotation);
var right = assignment.Right.RemoveParentheses();
if (right is BinaryExpressionSyntax binaryExpression && binaryExpression.Kind() == SyntaxKind.CoalesceExpression)
{
return(CoalesceAssignmentExpression(context, assignment.Left, binaryExpression.Right));
}
else if (right is ConditionalExpressionSyntax conditional)
{
ConditionalSimplification.TryGetExpressionComparedToNull(conditional.Condition, out compared, out var comparedIsNullInTrue);
if (context.IsCoalesceAssignmentSupported && ConditionalSimplification.IsCoalesceAssignmentCandidate(conditional, compared))
{
return(CoalesceAssignmentExpression(context,
(conditional.GetFirstNonParenthesizedParent() as AssignmentExpressionSyntax).Left,
(comparedIsNullInTrue ? conditional.WhenTrue : conditional.WhenFalse).RemoveParentheses()));
}
}
break;
}