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