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#
# Copyright (C) 2008-2010 Wayne Meissner
# Copyright (C) 2008 Mike Dalessio
#
# All rights reserved.
#
# This file is part of ruby-ffi.
#
# This code is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License version 3 only, as
# published by the Free Software Foundation.
#
# This code 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
# version 3 for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# version 3 along with this work. If not, see <http://www.gnu.org/licenses/>.
#
module FFI
class AutoPointer < Pointer
extend DataConverter
# call-seq:
# AutoPointer.new(pointer, method) => the passed Method will be invoked at GC time
# AutoPointer.new(pointer, proc) => the passed Proc will be invoked at GC time (SEE WARNING BELOW!)
# AutoPointer.new(pointer) { |p| ... } => the passed block will be invoked at GC time (SEE WARNING BELOW!)
# AutoPointer.new(pointer) => the pointer's release() class method will be invoked at GC time
#
# WARNING: passing a proc _may_ cause your pointer to never be GC'd, unless you're careful to avoid trapping a reference to the pointer in the proc. See the test specs for examples.
# WARNING: passing a block will cause your pointer to never be GC'd. This is bad.
#
# Please note that the safest, and therefore preferred, calling
# idiom is to pass a Method as the second parameter. Example usage:
#
# class PointerHelper
# def self.release(pointer)
# ...
# end
# end
#
# p = AutoPointer.new(other_pointer, PointerHelper.method(:release))
#
# The above code will cause PointerHelper#release to be invoked at GC time.
#
# The last calling idiom (only one parameter) is generally only
# going to be useful if you subclass AutoPointer, and override
# release(), which by default does nothing.
#
def initialize(ptr, proc=nil, &block)
super(ptr)
raise TypeError, "Invalid pointer" if ptr.nil? || !ptr.kind_of?(Pointer) \
|| ptr.kind_of?(MemoryPointer) || ptr.kind_of?(AutoPointer)
@releaser = if proc
raise RuntimeError.new("proc must be callable") unless proc.respond_to?(:call)
CallableReleaser.new(ptr, proc)
else
raise RuntimeError.new("no release method defined") unless self.class.respond_to?(:release)
DefaultReleaser.new(ptr, self.class)
end
ObjectSpace.define_finalizer(self, @releaser)
self
end
def free
@releaser.free
end
def autorelease=(autorelease)
@releaser.autorelease=(autorelease)
end
class Releaser
def initialize(ptr, proc)
@ptr = ptr
@proc = proc
@autorelease = true
end
def free
if @ptr
release(@ptr)
@autorelease = false
@ptr = nil
@proc = nil
end
end
def autorelease=(autorelease)
@autorelease = autorelease if @ptr
end
def call(*args)
release(@ptr) if @autorelease && @ptr
end
end
class DefaultReleaser < Releaser
def release(ptr)
@proc.release(ptr)
end
end
class CallableReleaser < Releaser
def release(ptr)
@proc.call(ptr)
end
end
def self.native_type
raise RuntimeError.new("no release method defined for #{self.inspect}") unless self.respond_to?(:release)
Type::POINTER
end
def self.from_native(val, ctx)
self.new(val)
end
end
end
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