204 lines
6.8 KiB
Ruby
204 lines
6.8 KiB
Ruby
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#
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# Copyright (C) 2008-2010 Wayne Meissner
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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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class AutoPointer < Pointer
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extend DataConverter
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# @overload initialize(pointer, method)
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# @param pointer [Pointer]
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# @param method [Method]
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# @return [self]
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# The passed Method will be invoked at GC time.
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# @overload initialize(pointer, proc)
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# @param pointer [Pointer]
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# @return [self]
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# The passed Proc will be invoked at GC time (SEE WARNING BELOW!)
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# @note WARNING: passing a proc _may_ cause your pointer to never be
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# GC'd, unless you're careful to avoid trapping a reference to the
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# pointer in the proc. See the test specs for examples.
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# @overload initialize(pointer) { |p| ... }
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# @param pointer [Pointer]
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# @yieldparam [Pointer] p +pointer+ passed to the block
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# @return [self]
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# The passed block will be invoked at GC time.
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# @note
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# WARNING: passing a block will cause your pointer to never be GC'd.
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# This is bad.
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# @overload initialize(pointer)
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# @param pointer [Pointer]
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# @return [self]
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# The pointer's release() class method will be invoked at GC time.
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#
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# @note The safest, and therefore preferred, calling
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# idiom is to pass a Method as the second parameter. Example usage:
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#
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# class PointerHelper
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# def self.release(pointer)
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# ...
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# end
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# end
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#
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# p = AutoPointer.new(other_pointer, PointerHelper.method(:release))
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#
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# The above code will cause PointerHelper#release to be invoked at GC time.
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#
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# @note
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# The last calling idiom (only one parameter) is generally only
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# going to be useful if you subclass {AutoPointer}, and override
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# #release, which by default does nothing.
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def initialize(ptr, proc=nil, &block)
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super(ptr.type_size, ptr)
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raise TypeError, "Invalid pointer" if ptr.nil? || !ptr.kind_of?(Pointer) \
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|| ptr.kind_of?(MemoryPointer) || ptr.kind_of?(AutoPointer)
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@releaser = if proc
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if not proc.respond_to?(:call)
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raise RuntimeError.new("proc must be callable")
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end
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CallableReleaser.new(ptr, proc)
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else
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if not self.class.respond_to?(:release)
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raise RuntimeError.new("no release method defined")
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end
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DefaultReleaser.new(ptr, self.class)
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end
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ObjectSpace.define_finalizer(self, @releaser)
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self
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end
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# @return [nil]
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# Free the pointer.
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def free
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@releaser.free
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end
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# @param [Boolean] autorelease
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# @return [Boolean] +autorelease+
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# Set +autorelease+ property. See {Pointer Autorelease section at Pointer}.
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def autorelease=(autorelease)
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@releaser.autorelease=(autorelease)
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end
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# @return [Boolean] +autorelease+
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# Get +autorelease+ property. See {Pointer Autorelease section at Pointer}.
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def autorelease?
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@releaser.autorelease
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end
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# @abstract Base class for {AutoPointer}'s releasers.
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#
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# All subclasses of Releaser should define a +#release(ptr)+ method.
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# A releaser is an object in charge of release an {AutoPointer}.
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class Releaser
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attr_accessor :autorelease
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# @param [Pointer] ptr
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# @param [#call] proc
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# @return [nil]
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# A new instance of Releaser.
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def initialize(ptr, proc)
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@ptr = ptr
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@proc = proc
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@autorelease = true
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end
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# @return [nil]
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# Free pointer.
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def free
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if @ptr
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release(@ptr)
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@autorelease = false
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@ptr = nil
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@proc = nil
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end
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end
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# @param args
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# Release pointer if +autorelease+ is set.
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def call(*args)
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release(@ptr) if @autorelease && @ptr
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end
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end
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# DefaultReleaser is a {Releaser} used when an {AutoPointer} is defined
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# without Proc or Method. In this case, the pointer to release must be of
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# a class derived from AutoPointer with a {release} class method.
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class DefaultReleaser < Releaser
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# @param [Pointer] ptr
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# @return [nil]
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# Release +ptr+ using the {release} class method of its class.
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def release(ptr)
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@proc.release(ptr)
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end
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end
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# CallableReleaser is a {Releaser} used when an {AutoPointer} is defined with a
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# Proc or a Method.
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class CallableReleaser < Releaser
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# Release +ptr+ by using Proc or Method defined at +ptr+
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# {AutoPointer#initialize initialization}.
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#
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# @param [Pointer] ptr
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# @return [nil]
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def release(ptr)
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@proc.call(ptr)
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end
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end
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# Return native type of AutoPointer.
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#
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# Override {DataConverter#native_type}.
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# @return [Type::POINTER]
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# @raise {RuntimeError} if class does not implement a +#release+ method
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def self.native_type
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if not self.respond_to?(:release)
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raise RuntimeError.new("no release method defined for #{self.inspect}")
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end
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Type::POINTER
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end
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# Create a new AutoPointer.
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#
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# Override {DataConverter#from_native}.
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# @overload self.from_native(ptr, ctx)
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# @param [Pointer] ptr
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# @param ctx not used. Please set +nil+.
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# @return [AutoPointer]
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def self.from_native(val, ctx)
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self.new(val)
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end
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end
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end
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