1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
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 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
# call-seq:
# ManagedStruct.new(pointer)
# ManagedStruct.new
#
# When passed a pointer, create a new ManagedStruct which will invoke the class method release() on
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
|
