protected override SignatureHelpModel GetModel(SemanticModel semanticModel, NullIfExpressionSyntax node, int position)
{
var span = node.Span;
var signature = SignatureHelpExtensions.GetNullIfSignatureItem();
var signatures = new[] { signature };
var commaToken = node.CommaToken;
var isBeforeComma = commaToken.IsMissing || position <= commaToken.Span.Start;
var parameterIndex = isBeforeComma ? 0 : 1;
return(new SignatureHelpModel(span, signatures, signature, parameterIndex));
}
protected override IEnumerable <SignatureItem> GetExpectedSignatures(SemanticModel semanticModel)
{
yield return(SignatureHelpExtensions.GetNullIfSignatureItem());
}