// INITIALIZATION
//_________________________________________________________________________________________
/// <summary>
/// Creates a new Binder instance.
/// </summary>
/// <param name="targetMethod"> A method to bind to. </param>
protected MethodBinder(BinderMethod targetMethod)
{
if (targetMethod == null)
{
throw new ArgumentNullException("targetMethod");
}
this.m_name = targetMethod.Name;
this.m_declaringType = targetMethod.DeclaringType;
this.m_functionLength = targetMethod.RequiredParameterCount +
targetMethod.OptionalParameterCount + (targetMethod.HasParamArray ? 1 : 0);
}
/// <summary>
/// Given a set of methods and a set of arguments, determines whether one of the methods
/// can be unambiguously selected. Throws an exception if this is not the case.
/// </summary>
/// <param name="methodHandles"> An array of handles to the candidate methods. </param>
/// <param name="engine"> The associated script engine. </param>
/// <param name="thisValue"> The value of the "this" keyword. </param>
/// <param name="arguments"> An array of parameter values. </param>
/// <returns> The index of the selected method. </returns>
public static int ResolveOverloads(RuntimeMethodHandle[] methodHandles, ScriptEngine engine, object thisValue, object[] arguments)
{
// Get methods from the handles.
var methods = new BinderMethod[methodHandles.Length];
for (int i = 0; i < methodHandles.Length; i++)
{
methods[i] = new BinderMethod(MethodBase.GetMethodFromHandle(methodHandles[i]));
}
// Keep a score for each method. Add one point if a type conversion is required, or
// a million points if a type conversion cannot be performed.
int[] demeritPoints = new int[methods.Length];
const int disqualification = 65536;
for (int i = 0; i < methods.Length; i++)
{
foreach (var argument in methods[i].GetArguments(arguments.Length))
{
// Get the input parameter.
object input;
switch (argument.Source)
{
case BinderArgumentSource.ThisValue:
input = thisValue;
break;
case BinderArgumentSource.InputParameter:
input = arguments[argument.InputParameterIndex];
break;
default:
continue;
}
// Unwrap the input parameter.
if (input is Jurassic.Library.ClrInstanceWrapper)
{
input = ((Jurassic.Library.ClrInstanceWrapper)input).WrappedInstance;
}
// Get the type of the output parameter.
Type outputType = argument.Type;
switch (Type.GetTypeCode(outputType))
{
case TypeCode.Boolean:
if ((input is bool) == false)
{
demeritPoints[i] += disqualification;
}
break;
case TypeCode.SByte:
case TypeCode.Int16:
case TypeCode.Int32:
case TypeCode.Int64:
case TypeCode.Byte:
case TypeCode.UInt16:
case TypeCode.UInt32:
case TypeCode.UInt64:
case TypeCode.Single:
case TypeCode.Decimal:
if (TypeUtilities.IsNumeric(input))
{
demeritPoints[i]++;
}
else
{
demeritPoints[i] += disqualification;
}
break;
case TypeCode.Double:
if (TypeUtilities.IsNumeric(input) == false)
{
demeritPoints[i] += disqualification;
}
break;
case TypeCode.Char:
if (TypeUtilities.IsString(input))
{
demeritPoints[i]++;
}
else
{
demeritPoints[i] += disqualification;
}
break;
case TypeCode.String:
if (TypeUtilities.IsString(input) == false && input != Null.Value)
{
demeritPoints[i] += disqualification;
}
break;
case TypeCode.DateTime:
case TypeCode.Object:
if (input == null || input == Undefined.Value)
{
demeritPoints[i] += disqualification;
}
else if (input == Null.Value)
{
if (outputType.IsValueType)
{
demeritPoints[i] += disqualification;
}
}
else if (outputType.IsInstanceOfType(input) == false)
{
demeritPoints[i] += disqualification;
}
break;
case TypeCode.Empty:
case TypeCode.DBNull:
throw new NotSupportedException(string.Format("{0} is not a supported parameter type.", outputType));
}
}
}
// Find the method(s) with the fewest number of demerit points.
int lowestScore = int.MaxValue;
var lowestIndices = new List <int>();
for (int i = 0; i < methods.Length; i++)
{
if (demeritPoints[i] < lowestScore)
{
lowestScore = demeritPoints[i];
lowestIndices.Clear();
}
if (demeritPoints[i] <= lowestScore)
{
lowestIndices.Add(i);
}
}
// Throw an error if the match is ambiguous.
if (lowestIndices.Count > 1)
{
var ambiguousMethods = new List <BinderMethod>(lowestIndices.Count);
ambiguousMethods.AddRange(lowestIndices.Select(index => methods[index]));
throw new JavaScriptException(engine, "TypeError", "The method call is ambiguous between the following methods: " + StringHelpers.Join(", ", ambiguousMethods));
}
// Throw an error is there is an invalid argument.
if (lowestIndices.Count == 1 && lowestScore >= disqualification)
{
throw new JavaScriptException(engine, "TypeError", string.Format("The best method overload {0} has some invalid arguments", methods[lowestIndices[0]]));
}
return(lowestIndices[0]);
}
