71 lines
1.2 KiB
Ruby
71 lines
1.2 KiB
Ruby
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# Weak Reference class that does not bother GCing.
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#
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# Usage:
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# foo = Object.new
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# foo.hash
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# foo = WeakRef.new(foo)
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# foo.hash
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# ObjectSpace.garbage_collect
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# foo.hash # => Raises WeakRef::RefError (because original GC'ed)
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require "delegate"
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class WeakRef<Delegater
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Exception :RefError
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ID_MAP = {}
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ID_REV_MAP = {}
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ObjectSpace.add_finalizer(lambda{|id|
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rid = ID_MAP[id]
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if rid
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ID_REV_MAP[rid] = nil
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ID_MAP[id] = nil
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end
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rid = ID_REV_MAP[id]
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if rid
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ID_REV_MAP[id] = nil
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ID_MAP[rid] = nil
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end
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})
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def initialize(orig)
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super
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@id = orig.id
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ObjectSpace.call_finalizer orig
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ID_MAP[@id] = self.id
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ID_REV_MAP[self.id] = @id
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end
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def __getobj__
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unless ID_MAP[@id]
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$@ = caller(1)
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$! = RefError.new("Illegal Reference - probably recycled")
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raise
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end
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ObjectSpace.id2ref(@id)
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# ObjectSpace.each_object do |obj|
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# return obj if obj.id == @id
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# end
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end
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def weakref_alive?
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if ID_MAP[@id]
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true
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else
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false
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end
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end
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def []
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__getobj__
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end
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end
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foo = Object.new
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p foo.hash
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foo = WeakRef.new(foo)
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p foo.hash
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ObjectSpace.garbage_collect
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p foo.hash
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