JezK
Edit File: managedstruct.rb
# Copyright (C) 2008 Mike Dalessio # # This file is part of ruby-ffi. # # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions are met: # # * Redistributions of source code must retain the above copyright notice, this # list of conditions and the following disclaimer. # * Redistributions in binary form must reproduce the above copyright notice # this list of conditions and the following disclaimer in the documentation # and/or other materials provided with the distribution. # * Neither the name of the Ruby FFI project nor the names of its contributors # may be used to endorse or promote products derived from this software # without specific prior written permission. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE # DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE # FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL # DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR # SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, # OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. module FFI # # FFI::ManagedStruct allows custom garbage-collection of your FFI::Structs. # # The typical use case would be when interacting with a library # that has a nontrivial memory management design, such as a linked # list or a binary tree. # # When the {Struct} instance is garbage collected, FFI::ManagedStruct will # invoke the class's release() method during object finalization. # # @example Example usage: # module MyLibrary # ffi_lib "libmylibrary" # attach_function :new_dlist, [], :pointer # attach_function :destroy_dlist, [:pointer], :void # end # # class DoublyLinkedList < FFI::ManagedStruct # @@@ # struct do |s| # s.name 'struct dlist' # s.include 'dlist.h' # s.field :head, :pointer # s.field :tail, :pointer # end # @@@ # # def self.release ptr # MyLibrary.destroy_dlist(ptr) # end # end # # begin # ptr = DoublyLinkedList.new(MyLibrary.new_dlist) # # do something with the list # end # # struct is out of scope, and will be GC'd using DoublyLinkedList#release # # class ManagedStruct < FFI::Struct # @overload initialize(pointer) # @param [Pointer] pointer # Create a new ManagedStruct which will invoke the class method #release on # @overload initialize # A new instance of FFI::ManagedStruct. def initialize(pointer=nil) raise NoMethodError, "release() not implemented for class #{self}" unless self.class.respond_to? :release raise ArgumentError, "Must supply a pointer to memory for the Struct" unless pointer super AutoPointer.new(pointer, self.class.method(:release)) end end end