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Edit File: autopointer.rb
# # Copyright (C) 2008-2010 Wayne Meissner # 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 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.type_size, ptr) raise TypeError, "Invalid pointer" if ptr.nil? || !ptr.kind_of?(Pointer) \ || ptr.kind_of?(MemoryPointer) || ptr.kind_of?(AutoPointer) @releaser = if proc if not proc.respond_to?(:call) raise RuntimeError.new("proc must be callable") end CallableReleaser.new(ptr, proc) else if not self.class.respond_to?(:release) raise RuntimeError.new("no release method defined") end 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 # @return [Boolean] +autorelease+ # Get +autorelease+ property. See {Pointer Autorelease section at Pointer}. def autorelease? @releaser.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 attr_accessor :autorelease # @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 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+ using the {release} class method of its class. 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 # Release +ptr+ by using Proc or Method defined at +ptr+ # {AutoPointer#initialize initialization}. # # @param [Pointer] ptr # @return [nil] 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 if not self.respond_to?(:release) raise RuntimeError.new("no release method defined for #{self.inspect}") end 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