/// <summary>
/// Collect all the available cast pairs, format is (target argument expression, potential conversion type)
/// </summary>
/// <param name="targetArgument"> The argument that need to be cast</param>
/// <param name="argumentList"> The argument list that contains the target argument to be cast </param>
/// <param name="invocationNode"> The invocation node that is the parent of "argumentList"</param>
/// <returns>
/// Return all the available cast pairs, format is (target argument expression, potential conversion type)
/// </returns>
public ImmutableArray <(TExpressionSyntax, ITypeSymbol)> GetPotentialConversionTypes(
SemanticModel semanticModel,
SyntaxNode root,
TArgumentSyntax targetArgument,
TArgumentListSyntax argumentList,
TInvocationSyntax invocationNode,
CancellationToken cancellationToken
)
{
// Implicit downcast appears on the argument of invocation node,
// get all candidate functions and extract potential conversion types
var symbolInfo = semanticModel.GetSymbolInfo(invocationNode, cancellationToken);
using var _ = ArrayBuilder <ISymbol> .GetInstance(out var candidateSymbols);
if (symbolInfo.Symbol != null) // BC42016: the only candidate symbol is symbolInfo.Symbol
{
candidateSymbols.Add(symbolInfo.Symbol);
}
else
{
candidateSymbols.AddRange(symbolInfo.CandidateSymbols);
}
using var __ = ArrayBuilder <(TExpressionSyntax, ITypeSymbol)> .GetInstance(
out var mutablePotentialConversionTypes
);
foreach (var candidateSymbol in candidateSymbols.OfType <IMethodSymbol>())
{
if (
CanArgumentTypesBeConvertedToParameterTypes(
semanticModel,
root,
argumentList,
candidateSymbol.Parameters,
targetArgument,
cancellationToken,
out var targetArgumentConversionType
) &&
GetExpressionOfArgument(targetArgument)
is TExpressionSyntax argumentExpression
)
{
mutablePotentialConversionTypes.Add(
(argumentExpression, targetArgumentConversionType)
);
}
}
// Sort the potential conversion types by inheritance distance, so that
// operations are in order and user can choose least specific types(more accurate)
mutablePotentialConversionTypes.Sort(
new InheritanceDistanceComparer <TExpressionSyntax>(semanticModel)
);
return(mutablePotentialConversionTypes.ToImmutable());
}
protected abstract SyntaxNode GetExpression(TInvocationSyntax memberAccess);
protected abstract bool HasNumberOfArguments(TInvocationSyntax invocation, int number);
// this will return null if there's no argument in the invocation // the check must be done beforehand protected abstract SyntaxNode GetFirstArgument(TInvocationSyntax invocation);