using System;
namespace Python.Runtime
{
///
/// Managed class that provides the implementation for reflected delegate
/// types. Delegates are represented in Python by generated type objects.
/// Each of those type objects is associated an instance of this class,
/// which provides its implementation.
///
[Serializable]
internal class DelegateObject : ClassBase
{
private readonly MethodBinder binder;
internal DelegateObject(Type tp) : base(tp)
{
binder = new MethodBinder(tp.GetMethod("Invoke"));
}
///
/// Given a PyObject pointer to an instance of a delegate type, return
/// the true managed delegate the Python object represents (or null).
///
private static Delegate? GetTrueDelegate(BorrowedReference op)
{
if (GetManagedObject(op) is CLRObject o)
{
var d = o.inst as Delegate;
return d;
}
return null;
}
internal override bool CanSubclass()
{
return false;
}
///
/// DelegateObject __new__ implementation. The result of this is a new
/// PyObject whose type is DelegateObject and whose ob_data is a handle
/// to an actual delegate instance. The method wrapped by the actual
/// delegate instance belongs to an object generated to relay the call
/// to the Python callable passed in.
///
public static NewReference tp_new(BorrowedReference tp, BorrowedReference args, BorrowedReference kw)
{
var self = (DelegateObject)GetManagedObject(tp)!;
if (!self.type.Valid)
{
return Exceptions.RaiseTypeError(self.type.DeletedMessage);
}
Type type = self.type.Value;
if (Runtime.PyTuple_Size(args) != 1)
{
return Exceptions.RaiseTypeError("class takes exactly one argument");
}
BorrowedReference method = Runtime.PyTuple_GetItem(args, 0);
if (Runtime.PyCallable_Check(method) != 1)
{
return Exceptions.RaiseTypeError("argument must be callable");
}
Delegate d = PythonEngine.DelegateManager.GetDelegate(type, new PyObject(method));
return CLRObject.GetReference(d, ClassManager.GetClass(type));
}
///
/// Implements __call__ for reflected delegate types.
///
public static NewReference tp_call(BorrowedReference ob, BorrowedReference args, BorrowedReference kw)
{
// TODO: add fast type check!
BorrowedReference pytype = Runtime.PyObject_TYPE(ob);
var self = (DelegateObject)GetManagedObject(pytype)!;
if (GetManagedObject(ob) is CLRObject o && o.inst is Delegate _)
{
return self.binder.Invoke(ob, args, kw);
}
return Exceptions.RaiseTypeError("invalid argument");
}
///
/// Implements __cmp__ for reflected delegate types.
///
public new static NewReference tp_richcompare(BorrowedReference ob, BorrowedReference other, int op)
{
if (op != Runtime.Py_EQ && op != Runtime.Py_NE)
{
return new NewReference(Runtime.PyNotImplemented);
}
BorrowedReference pytrue = Runtime.PyTrue;
BorrowedReference pyfalse = Runtime.PyFalse;
// swap true and false for NE
if (op != Runtime.Py_EQ)
{
pytrue = Runtime.PyFalse;
pyfalse = Runtime.PyTrue;
}
Delegate? d1 = GetTrueDelegate(ob);
Delegate? d2 = GetTrueDelegate(other);
return new NewReference(d1 == d2 ? pytrue : pyfalse);
}
}
}