Module: Affect::Cont

Extended by:
Cont
Included in:
Cont
Defined in:
lib/affect/cont.rb

Constant Summary collapse

@@stack =

holds objects of the form [bool, Continuation] where bool siginifies a

[]

Instance Method Summary collapse

Instance Method Details

#abort(v) ⇒ Object 



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# File 'lib/affect/cont.rb', line 16

def abort(v)
  (@@stack.pop)[1].(v)
end

#capture(&block) ⇒ Object 



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# File 'lib/affect/cont.rb', line 20

def capture(&block)
  callcc { |outer|
    @@stack << [true, outer]
    abort(block.())
  }
end

#escape ⇒ Object 



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# File 'lib/affect/cont.rb', line 27

def escape
  callcc do |esc|
    unwound_continuations = unwind_stack
    cont_proc = lambda { |v|
      callcc do |ret|
        @@stack << [true, ret]
        unwound_continuations.each { |c| @@stack << [nil, c] }
        esc.call(v)
      end
    }
    abort(yield(cont_proc))
  end
end

#unwind_stack ⇒ Object 



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# File 'lib/affect/cont.rb', line 41

def unwind_stack
unwound = []
  while @@stack.last && !(@@stack.last)[0]
    unwound << (@@stack.pop)[1]
  end
  unwound.reverse
end