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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
# @overload initialize(pointer, method)
# @param [Pointer] pointer
# @param [Method] method
# @return [self]
# The passed Method will be invoked at GC time.
# @overload initialize(pointer, proc)
# @param [Pointer] pointer
# @return [self]
# The passed Proc will be invoked at GC time (SEE WARNING BELOW!)
# @note 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.
# @overload initialize(pointer) { |p| ... }
# @param [Pointer] pointer
# @yieldparam [Pointer] p +pointer+ passed to the block
# @return [self]
# The passed block will be invoked at GC time.
# @note WARNING: passing a block will cause your pointer to never be GC'd. This is bad.
# @overload initialize(pointer)
# @param [Pointer] pointer
# @return [self]
# The pointer's release() class method will be invoked at GC time.
#
# @note 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.
#
# @note
# 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
# @return [nil]
# Free the pointer.
def free
@releaser.free
end
# @param [Boolean] autorelease
# @return [Boolean] +autorelease+
# Set +autorelease+ property. See {Pointer Autorelease section at Pointer}.
def autorelease=(autorelease)
@releaser.autorelease=(autorelease)
end
# @abstract Base class for {AutoPointer}'s releasers.
#
# All subclasses of Releaser should define a +#release(ptr)+ method.
# A releaser is an object in charge of release an {AutoPointer}.
class Releaser
# @param [Pointer] ptr
# @param [#call] proc
# @return [nil]
# A new instance of Releaser.
def initialize(ptr, proc)
@ptr = ptr
@proc = proc
@autorelease = true
end
# @return [nil]
# Free pointer.
def free
if @ptr
release(@ptr)
@autorelease = false
@ptr = nil
@proc = nil
end
end
# @param [Boolean] autorelease
# @return [Boolean] autorelease
# Set +autorelease+ attribute for pointer managed by Releaser.
def autorelease=(autorelease)
@autorelease = autorelease if @ptr
end
# @param args
# Release pointer if +autorelease+ is set.
def call(*args)
release(@ptr) if @autorelease && @ptr
end
end
# DefaultReleaser is a {Releaser} used when an {AutoPointer} is defined without Proc
# or Method. In this case, the pointer to release must be of a class derived from
# AutoPointer with a +#release+ class method.
class DefaultReleaser < Releaser
# @param [Pointer] ptr
# @return [nil]
# Release +ptr+ by using his #release class method.
def release(ptr)
@proc.release(ptr)
end
end
# CallableReleaser is a {Releaser} used when an {AutoPointer} is defined with a
# Proc or a Method.
class CallableReleaser < Releaser
# @param [Pointer] ptr
# @return [nil]
# Release +ptr+ by using Proc or Method defined at +ptr+ {AutoPointer#initialize initialization}.
def release(ptr)
@proc.call(ptr)
end
end
# Return native type of AutoPointer.
#
# Override {DataConverter#native_type}.
# @return [Type::POINTER]
# @raise {RuntimeError} if class does not implement a +#release+ method
def self.native_type
raise RuntimeError.new("no release method defined for #{self.inspect}") unless self.respond_to?(:release)
Type::POINTER
end
# Create a new AutoPointer.
#
# Override {DataConverter#from_native}.
# @overload self.from_native(ptr, ctx)
# @param [Pointer] ptr
# @param ctx not used. Please set +nil+.
# @return [AutoPointer]
def self.from_native(val, ctx)
self.new(val)
end
end
end
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