using System;
using System.Reflection;
using System.Runtime.InteropServices;
namespace Python.Runtime
{
///
/// Provides the implementation for reflected interface types. Managed
/// interfaces are represented in Python by actual Python type objects.
/// Each of those type objects is associated with an instance of this
/// class, which provides the implementation for the Python type.
///
[Serializable]
internal class InterfaceObject : ClassBase
{
internal ConstructorInfo ctor;
internal InterfaceObject(Type tp) : base(tp)
{
var coclass = (CoClassAttribute)Attribute.GetCustomAttribute(tp, cc_attr);
if (coclass != null)
{
ctor = coclass.CoClass.GetConstructor(Type.EmptyTypes);
}
}
private static Type cc_attr;
static InterfaceObject()
{
cc_attr = typeof(CoClassAttribute);
}
///
/// Implements __new__ for reflected interface types.
///
public static IntPtr tp_new(IntPtr tp, IntPtr args, IntPtr kw)
{
var self = (InterfaceObject)GetManagedObject(tp);
var nargs = Runtime.PyTuple_Size(args);
Type type = self.type;
object obj;
if (nargs == 1)
{
IntPtr inst = Runtime.PyTuple_GetItem(args, 0);
var co = GetManagedObject(inst) as CLRObject;
if (co == null || !type.IsInstanceOfType(co.inst))
{
Exceptions.SetError(Exceptions.TypeError, $"object does not implement {type.Name}");
return IntPtr.Zero;
}
obj = co.inst;
}
else if (nargs == 0 && self.ctor != null)
{
obj = self.ctor.Invoke(null);
if (obj == null || !type.IsInstanceOfType(obj))
{
Exceptions.SetError(Exceptions.TypeError, "CoClass default constructor failed");
return IntPtr.Zero;
}
}
else
{
Exceptions.SetError(Exceptions.TypeError, "interface takes exactly one argument");
return IntPtr.Zero;
}
return self.WrapObject(obj);
}
///
/// Wrap the given object in an interface object, so that only methods
/// of the interface are available.
///
public IntPtr WrapObject(object impl)
{
var objPtr = CLRObject.GetInstHandle(impl, pyHandle);
return objPtr;
}
///
/// Expose the wrapped implementation through attributes in both
/// converted/encoded (__implementation__) and raw (__raw_implementation__) form.
///
public static IntPtr tp_getattro(IntPtr ob, IntPtr key)
{
var clrObj = (CLRObject)GetManagedObject(ob);
if (!Runtime.PyString_Check(key))
{
return Exceptions.RaiseTypeError("string expected");
}
string name = Runtime.GetManagedString(key);
if (name == "__implementation__")
{
return Converter.ToPython(clrObj.inst);
}
else if (name == "__raw_implementation__")
{
return CLRObject.GetInstHandle(clrObj.inst);
}
return Runtime.PyObject_GenericGetAttr(ob, key);
}
}
}