note
   description: "Wrapper for a generic C structure"
   copyright:
      "[
               (C) 2005,2008 Paolo Redaelli, Raphael Mack <mail@raphael-mack.de>
               This library is free software; you can redistribute it and/or
               modify it under the terms of the GNU Lesser General Public License
               as published by the Free Software Foundation; either version 2.1 of
               the License, or (at your option) any later version.

               This library is distributed in the hope that it will be useful, but
               WITHOUT ANY WARRANTY; without even the implied warranty of
               MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
               Lesser General Public License for more details.

               You should have received a copy of the GNU Lesser General Public
               License along with this library; if not, write to the Free Software
               Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
               02110-1301 USA
         ]"
   license: "LGPL v2 or later"

deferred class C_STRUCT
   -- Wrapper for a data structure implemented in C programming language.

inherit
   WRAPPER

feature {} -- Initialization
   from_external_copy (other: POINTER)
      do
         --dispose
         if other.is_not_null then
            handle := malloc(struct_size)
            handle := memcpy(handle, other, struct_size)
         else
            handle := default_pointer
         end
      end

   allocate
         -- Allocate an uninitialized structure.
         -- Memory is allocated but NOT set to zero. This may not be what you want. See implementation
      do
         handle := malloc(struct_size)
         -- This feature used to invoke calloc to set the allocated memory to zero.
         -- calloc actually has different signatures on 32 and 64 bits machines.
         -- so we cannot write correct code as long as we rely on SmartEiffel or as long as we do not have (automatic) convertions in classes.
         -- Please note that initializing struct memory to zero may not what
         -- we want, for example I don't know if binary 0 also means zero
         -- when representing a floating point number. Paolo 2010-06-19
         if handle.is_null then
            raise_exception(No_more_memory)
         end
      ensure
         memory_allocated: handle.is_not_null
      end

feature {ANY} -- Copying
   copy (other: like Current)
      do
         dispose
         if other.handle.is_not_null then
            handle := malloc(struct_size)
            handle := memcpy(handle, other.handle, struct_size)
         else
            handle := default_pointer
         end
      end

   is_equal (another: like Current): BOOLEAN
      do
         Result := Current.handle = another.handle
      end

feature {}
   -- Access to C features
   -- struct_size should be exported to WRAPPER, to be able to check size
   -- before copying
   struct_size: like size_t
      deferred
      end

feature {WRAPPER_HANDLER} -- Destroying
   free_handle
         -- release the external memory
      do
         free(handle)
         -- Note free(NULL) is a harmless non-operation.
      end

end -- class C_STRUCT