private LambdaForm MakeArgumentCombinationForm(int pos, MethodType combinerType, bool keepArguments, bool dropResult)
{
LambdaFormBuffer buf = Buffer();
buf.StartEdit();
int combinerArity = combinerType.ParameterCount();
int resultArity = (dropResult ? 0 : 1);
assert(pos <= MethodType.MAX_JVM_ARITY);
assert(pos + resultArity + (keepArguments ? combinerArity : 0) <= LambdaForm.Arity_Renamed);
assert(pos > 0); // cannot filter the MH arg itself
assert(combinerType == combinerType.BasicType());
assert(combinerType.ReturnType() != typeof(void) || dropResult);
BoundMethodHandle.SpeciesData oldData = OldSpeciesData();
BoundMethodHandle.SpeciesData newData = NewSpeciesData(L_TYPE);
// The newly created LF will run with a different BMH.
// Switch over any pre-existing BMH field references to the new BMH class.
Name oldBaseAddress = LambdaForm.Parameter(0); // BMH holding the values
buf.ReplaceFunctions(oldData.GetterFunctions(), newData.GetterFunctions(), oldBaseAddress);
Name newBaseAddress = oldBaseAddress.withConstraint(newData);
buf.RenameParameter(0, newBaseAddress);
Name getCombiner = new Name(newData.GetterFunction(oldData.FieldCount()), newBaseAddress);
Object[] combinerArgs = new Object[1 + combinerArity];
combinerArgs[0] = getCombiner;
Name[] newParams;
if (keepArguments)
{
newParams = new Name[0];
System.Array.Copy(LambdaForm.Names, pos + resultArity, combinerArgs, 1, combinerArity);
}
else
{
newParams = new Name[combinerArity];
BasicType[] newTypes = basicTypes(combinerType.ParameterList());
for (int i = 0; i < newTypes.Length; i++)
{
newParams[i] = new Name(pos + i, newTypes[i]);
}
System.Array.Copy(newParams, 0, combinerArgs, 1, combinerArity);
}
Name callCombiner = new Name(combinerType, combinerArgs);
// insert the two new expressions
int exprPos = LambdaForm.Arity();
buf.InsertExpression(exprPos + 0, getCombiner);
buf.InsertExpression(exprPos + 1, callCombiner);
// insert new arguments, if needed
int argPos = pos + resultArity; // skip result parameter
foreach (Name newParam in newParams)
{
buf.InsertParameter(argPos++, newParam);
}
assert(buf.LastIndexOf(callCombiner) == exprPos + 1 + newParams.Length);
if (!dropResult)
{
buf.ReplaceParameterByCopy(pos, exprPos + 1 + newParams.Length);
}
return(buf.EndEdit());
}
