/// <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="argumentNodes">The argument nodes, can be new {null,null}.</param>
/// <param name="argumentTypes">The argument type references to match.</param>
/// <returns>The number of "best match" methods.</returns>
private static int FindBestSignature(FunctionSignature[] signatures, SingleValueNode[] argumentNodes, IEdmTypeReference[] argumentTypes)
{
Debug.Assert(signatures != null, "signatures != null");
Debug.Assert(argumentTypes != null, "argumentTypes != null");
Debug.Assert(signatures.All(s => s.ArgumentTypes != null && s.ArgumentTypes.All(t => t.IsODataPrimitiveTypeKind())), "All signatures must have only primitive argument types.");
List<FunctionSignature> applicableSignatures = signatures.Where(signature => IsApplicable(signature, argumentNodes, argumentTypes)).ToList();
if (applicableSignatures.Count > 1)
{
applicableSignatures = FindBestApplicableSignatures(applicableSignatures, argumentTypes);
}
int result = applicableSignatures.Count;
if (result == 1)
{
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)
{
if (applicableSignatures[0].ArgumentTypes[0].Definition.IsEquivalentTo(applicableSignatures[1].ArgumentTypes[0].Definition))
{
FunctionSignature nullableMethod =
applicableSignatures[0].ArgumentTypes[0].IsNullable ?
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, argumentNodes, 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;
}
/// <summary>Checks whether the specified method is applicable given the argument expressions.</summary>
/// <param name="signature">The candidate function signature to check.</param>
/// <param name="argumentNodes">The argument nodes, can be new {null,null}.</param>
/// <param name="argumentTypes">The argument types to match.</param>
/// <returns>An applicable function signature if all argument types can be promoted; 'null' otherwise.</returns>
private static bool IsApplicable(FunctionSignature signature, SingleValueNode[] argumentNodes, IEdmTypeReference[] argumentTypes)
{
Debug.Assert(signature != null, "signature != null");
Debug.Assert(argumentTypes != null, "argumentTypes != null");
if (signature.ArgumentTypes.Length != argumentTypes.Length)
{
return false;
}
for (int i = 0; i < argumentTypes.Length; ++i)
{
if (!CanPromoteNodeTo(argumentNodes[i], argumentTypes[i], signature.ArgumentTypes[i]))
{
return false;
}
}
return true;
}
/// <summary>Finds the exact fitting function for the specified arguments.</summary>
/// <param name="functions">Functions to consider.</param>
/// <param name="argumentTypes">Types of the arguments for the function.</param>
/// <returns>The exact fitting function; null if no exact match was found.</returns>
internal static FunctionSignature FindExactFunctionSignature(FunctionSignature[] functions, IEdmTypeReference[] argumentTypes)
{
Debug.Assert(functions != null, "functions != null");
Debug.Assert(argumentTypes != null, "argumentTypes != null");
for (int functionIndex = 0; functionIndex < functions.Length; functionIndex++)
{
FunctionSignature functionSignature = functions[functionIndex];
bool matchFound = true;
if (functionSignature.ArgumentTypes.Length != argumentTypes.Length)
{
continue;
}
for (int argumentIndex = 0; argumentIndex < argumentTypes.Length; argumentIndex++)
{
IEdmTypeReference functionSignatureArgumentType = functionSignature.ArgumentTypes[argumentIndex];
IEdmTypeReference argumentType = argumentTypes[argumentIndex];
Debug.Assert(functionSignatureArgumentType.IsODataPrimitiveTypeKind(), "Only primitive arguments are supported for functions.");
if (!argumentType.IsODataPrimitiveTypeKind())
{
matchFound = false;
break;
}
if (!argumentType.IsEquivalentTo(functionSignatureArgumentType))
{
matchFound = false;
break;
}
}
if (matchFound)
{
return functionSignature;
}
}
return null;
}
