/// <summary>Finds the best methods for the specified arguments given a candidate method enumeration.</summary>
/// <param name="signatures">The candidate function signatures.</param>
/// <param name="argumentTypes">The argument types to match.</param>
/// <returns>The number of "best match" methods.</returns>
private static int FindBestSignature(FunctionSignature[] signatures, ResourceType[] argumentTypes)
{
Debug.Assert(signatures != null, "signatures != null");
Debug.Assert(argumentTypes != null, "argumentTypes != null");
Debug.Assert(argumentTypes.All(t => t == null || t.ResourceTypeKind == ResourceTypeKind.Primitive), "All argument types must be primitive or null.");
Debug.Assert(signatures.All(s => s.ArgumentTypes != null && s.ArgumentTypes.All(t => t.ResourceTypeKind == ResourceTypeKind.Primitive)), "All signatures must have only primitive argument types.");
List<FunctionSignature> applicableSignatures = signatures.Where(signature => IsApplicable(signature, argumentTypes)).ToList();
if (applicableSignatures.Count > 1)
{
applicableSignatures = FindBestApplicableSignatures(applicableSignatures, argumentTypes);
}
int result = applicableSignatures.Count;
if (result == 1)
{
// TODO: deal with the situation that we started off with all non-open types
// and end up with all open types; see RequestQueryParser.FindBestMethod.
// Ignored for now since we don't support open types yet.
FunctionSignature signature = applicableSignatures[0];
for (int i = 0; i < argumentTypes.Length; i++)
{
argumentTypes[i] = signature.ArgumentTypes[i];
}
result = 1;
}
else if (result > 1)
{
// We may have the case for operators (which C# doesn't) in which we have a nullable operand
// and a non-nullable operand. We choose to convert the one non-null operand to nullable in that
// case (the binary expression will lift to null).
if (argumentTypes.Length == 2 && result == 2 &&
TypeUtils.GetNonNullableType(applicableSignatures[0].ArgumentTypes[0].InstanceType) ==
TypeUtils.GetNonNullableType(applicableSignatures[1].ArgumentTypes[0].InstanceType))
{
FunctionSignature nullableMethod =
TypeUtils.TypeAllowsNull(applicableSignatures[0].ArgumentTypes[0].InstanceType) ?
applicableSignatures[0] :
applicableSignatures[1];
argumentTypes[0] = nullableMethod.ArgumentTypes[0];
argumentTypes[1] = nullableMethod.ArgumentTypes[1];
// TODO: why is this necessary? We keep it here for now since the product has it but assert
// that nothing new was found.
int signatureCount = FindBestSignature(signatures, argumentTypes);
Debug.Assert(signatureCount == 1, "signatureCount == 1");
Debug.Assert(argumentTypes[0] == nullableMethod.ArgumentTypes[0], "argumentTypes[0] == nullableMethod.ArgumentTypes[0]");
Debug.Assert(argumentTypes[1] == nullableMethod.ArgumentTypes[1], "argumentTypes[1] == nullableMethod.ArgumentTypes[1]");
return signatureCount;
}
}
return result;
}