# $Id: orderedhash.rb 14 2008-03-02 05:42:30Z warchild $
#
# Copyright (c) 2008, Jon Hart 
# All rights reserved.
# 
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# modification, are permitted provided that the following conditions are met:
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#       names of its contributors may be used to endorse or promote products
#       derived from this software without specific prior written permission.
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# THIS SOFTWARE IS PROVIDED BY Jon Hart ``AS IS'' AND ANY
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#
module Racket
module Misc
# Simple ordered hash. 
#
# XXX: todo -- add a method for moving/shifting
# members around
class OrderedHash < Hash
  def initialize
    @keys = []
  end

  def []=(key, val)
    @keys << key unless (self[key])
    super
  end

  def delete(key)
    @keys.delete(key)
    super
  end

  def each
    @keys.each { |k| yield k, self[k] }
  end

  def each_key
    @keys.each { |k| yield k }
  end

  def each_value
    @keys.each { |k| yield self[k] }
  end
end
end
end
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