File : gnatcom-create-com_interface.adb
------------------------------------------------------------------------------
-- --
-- GNATCOM - Ada 95 COM/DCOM/COM+ Development Framework and Tools --
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-- G N A T C O M . C R E A T E . C O M _ I N T E R F A C E --
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-- B o d y --
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-- $Revision: 1.3 $
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-- Copyright (C) 1999, 2000, 2001 David Botton --
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-- As a special exception, if other files instantiate generics from this --
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------------------------------------------------------------------------------
with Ada.Unchecked_Conversion;
with Ada.Unchecked_Deallocation;
package body GNATCOM.Create.COM_Interface is
procedure Free_Object (Pointer : in out Pointer_To_CoClass);
procedure Free_Interface (Pointer : in System.Address);
function InterlockedIncrement
(lpAddend : access Interfaces.C.long) return Interfaces.C.long;
pragma Import (StdCall, InterlockedIncrement, "InterlockedIncrement");
-- Win32 API for protected increment of a long
function InterlockedDecrement
(lpAddend : access Interfaces.C.long) return Interfaces.C.long;
pragma Import (StdCall, InterlockedDecrement, "InterlockedDecrement");
-- Win32 API for protected decrement of a long
------------
-- AddRef --
------------
function AddRef (This : access COM_Interface_Type)
return Interfaces.C.unsigned_long
is
Result : Interfaces.C.long;
begin
-- Object wide reference increment
Result := InterlockedIncrement (This.CoClass.Ref_Count'Access);
-- Interface reference increment
Result := InterlockedIncrement (This.Ref_Count'Access);
return Interfaces.C.unsigned_long (This.Ref_Count);
end AddRef;
--------------------
-- QueryInterface --
--------------------
function QueryInterface
(This : access COM_Interface_Type;
riid : in GNATCOM.Types.Pointer_To_GUID;
ppvObject : access GNATCOM.Types.Pointer_To_Void)
return GNATCOM.Types.HRESULT
is
use type GNATCOM.Types.GUID;
New_Interface : aliased Pointer_To_COM_Interface_Type;
Result : Interfaces.C.long;
begin
-- GNATCOM implements COM objects using a technique often
-- called "tear-off" interfaces. Interfaces are created
-- as needed and requested. This behavior has many benefits
-- and is also used in the C++ world when there is a need
-- to dynamicly create interfaces and when there is a need
-- to control resources on an interface by interface level.
-- IUnknown must always return the "official" IUnknown for the
-- object, so we retrieve it from the CoClass
if riid.all = GNATCOM.Types.IID_IUnknown then
-- Add a ref count to the Interface
Result := InterlockedIncrement
(This.CoClass.IUnknown.Ref_Count'Access);
-- Add an Object wide ref count
Result := InterlockedIncrement (This.CoClass.Ref_Count'Access);
-- Set return interface to the "official" IUnknown
ppvObject.all := This.CoClass.IUnknown.all'Address;
return S_OK;
end if;
-- Loop through IID map in object to see if it supports the
-- requested IID in riid
for N in
This.CoClass.IID_Map.all'First .. This.CoClass.IID_Map.all'Last
loop
if riid.all = This.CoClass.IID_Map (N).IID then
-- Create a new Interface pointer, ie. a pointer
-- to a record containing as the first member a
-- pointer to a virtual function table, ala C++
New_Interface := new COM_Interface_Type;
-- Point to the virtual table of that matches the
-- found IID
New_Interface.Vtbl := This.CoClass.IID_Map (N).Vtbl;
-- The next entries in the record contain a pointer to
-- our object and the interfaces reference count
New_Interface.CoClass := This.CoClass;
-- Add a ref count to the Object wide ref count,
-- the COM_Interface_Type already has a ref count
-- built in, so we need not add a ref count to the
-- interface also here.
Result := InterlockedIncrement (This.CoClass.Ref_Count'Access);
-- Set return to the new interface
ppvObject.all := New_Interface.all'Address;
return S_OK;
end if;
end loop;
-- No interface matches set return to null
ppvObject.all := System.Null_Address;
-- See if there is a user provided QueryInterface by
-- dispatching on the QueryInterface method of the Object
-- for any custom handling of interfaces.
return QueryInterface (CoClass_Type'Class (This.CoClass.all),
This,
riid,
ppvObject);
end QueryInterface;
--------------------
-- QueryInterface --
--------------------
function QueryInterface
(Dispatch : in CoClass_Type;
This : access COM_Interface_Type;
riid : in GNATCOM.Types.Pointer_To_GUID;
ppvObject : access GNATCOM.Types.Pointer_To_Void)
return GNATCOM.Types.HRESULT
is
pragma Warnings (Off, Dispatch);
pragma Warnings (Off, This);
pragma Warnings (Off, riid);
pragma Warnings (Off, ppvObject);
begin
-- Default implementation of custom QueryInterface for Objects
-- just returns E_NOINTERFACE. Any over ride on QueryInterface
-- must return this value if it does not handle the QueryInteface
-- request.
return E_NOINTERFACE;
end QueryInterface;
-------------
-- Release --
-------------
function Release (This : access COM_Interface_Type)
return Interfaces.C.unsigned_long
is
use type Interfaces.C.long;
Result : Interfaces.C.long;
begin
-- Reduce the Object wide reference count
Result := InterlockedDecrement (This.CoClass.Ref_Count'Access);
-- Reduce the Interface ref count and check to see if this
-- is the last release
if InterlockedDecrement (This.Ref_Count'Access) /= 0 then
return Interfaces.C.unsigned_long (This.Ref_Count);
else
-- Last reference to the interface released, so free interface
Free_Interface (This.all'Address);
return 0;
end if;
end Release;
-------------
-- Release --
-------------
procedure Release (This : access COM_Interface_Type) is
Result : Interfaces.C.unsigned_long;
begin
-- The results of a release are in general bogus as
-- any time proxies are introduced, the actual result
-- returned to a client will not reflect the true
-- result returned from a release. This function
-- provides an easy way for other parts of the framework
-- to call a release and ignore the return value.
Result := Release (This);
end Release;
-----------------
-- Free_Object --
-----------------
procedure Free_Object (Pointer : in out Pointer_To_CoClass) is
procedure Free_CoClass is
new Ada.Unchecked_Deallocation (CoClass_Type'Class,
Pointer_To_CoClass);
procedure Free is
new Ada.Unchecked_Deallocation (COM_Interface_Type,
Pointer_To_COM_Interface_Type);
begin
-- First deallocate the "Official" IUnknown Interface
Free (Pointer.IUnknown);
-- Deallocate the Object
Free_CoClass (Pointer);
end Free_Object;
--------------------
-- Free_Interface --
--------------------
procedure Free_Interface (Pointer : in System.Address) is
use type Interfaces.C.long;
function To_Pointer_To_COM_Interface_Type is
new Ada.Unchecked_Conversion (System.Address,
Pointer_To_COM_Interface_Type);
procedure Free is
new Ada.Unchecked_Deallocation (COM_Interface_Type,
Pointer_To_COM_Interface_Type);
Interface : Pointer_To_COM_Interface_Type;
CoClass : Pointer_To_CoClass;
Result : Interfaces.C.long;
begin
Interface := To_Pointer_To_COM_Interface_Type (Pointer);
CoClass := Interface.CoClass;
-- If this is the official IUnknown, don't deallocate
-- it may be needed again. It is deallocated when
-- the object is deallocated.
if Interface.CoClass.IUnknown /= Interface then
Free (Interface);
end if;
if CoClass.Ref_Count < 1 then
-- All interfaces to this COM object have been released
-- so free the COM Object
Free_Object (CoClass);
-- Reduce the global component count since the object has
-- been deallocated.
Result := InterlockedDecrement
(GNATCOM.Create.Component_Count'Access);
end if;
-- Initiate a check to see if the COM objects host container
-- should shut down. This is a no-op for Inproc Servers.
GNATCOM.Create.Can_Close;
end Free_Interface;
-------------------
-- Create_Object --
-------------------
function Create_Object (Class_Object : Pointer_To_CoClass)
return Pointer_To_COM_Interface_Type
is
First_Interface : Pointer_To_COM_Interface_Type;
begin
-- Create out first Interface Pointer for the COM Object
First_Interface := new COM_Interface_Type;
-- Place pointer to object in to Interface
First_Interface.CoClass := Class_Object;
-- Make this first interface the "Official" IUnknown for
-- the object
if First_Interface.CoClass.IUnknown = null then
First_Interface.CoClass.IUnknown := First_Interface;
end if;
return First_Interface;
end Create_Object;
end GNATCOM.Create.COM_Interface;