#
# The ArrayFields module implements methods which allow an Array to be indexed
# by String or Symbol. It is not required to manually use this module to extend
# Array's - they are auto-extended when Array#fields= is called
#
  module ArrayFields 
#{{{
    VERSION = '3.0.0'
    def [](idx, *args) 
#{{{
      if @fields and String === idx or Symbol === idx
        pos = @fieldpos[idx]
        return nil unless pos
        super(pos, *args)
      else
        super
      end
#}}}
    end
    alias slice []
    def []=(idx, *args) 
#{{{
      if @fields and String === idx or Symbol === idx 
        pos = @fieldpos[idx]
        @fieldpos[idx] = pos = size unless pos
        super(pos, *args)
      else
        super
      end
#}}}
    end
    def at idx
#{{{
      if @fields and String === idx or Symbol === idx
        pos = @fieldpos[idx]
        return nil unless pos
        super pos
      else
        super
      end
#}}}
    end
    def delete_at idx
#{{{
      if @fields and String === idx or Symbol === idx
        pos = @fieldpos[idx]
        return nil unless pos
        super pos
      else
        super
      end
#}}}
    end
    def fill(obj, *args)
#{{{
      idx = args.first
      if idx and @fields and String === idx or Symbol === idx
        idx = args.shift
        pos = @fieldpos[idx]
        super(obj, pos, *args)
      else
        super
      end
#}}}
    end
    def values_at(*idxs)
#{{{
      idxs.flatten!
      if @fields
        idxs.map!{|i| (String === i or Symbol === i) ? @fieldpos[i] : i}
      end
      super(*idxs)
#}}}
    end
    alias indices values_at
    alias indexes values_at 
    def slice!(*args)
#{{{
      ret = self[*args]
      self[*args] = nil
      ret
#}}}
    end
    def each_with_field
#{{{
      each_with_index do |elem, i|
        yield elem, @fields[i]
      end
#}}}
    end
#}}}
  end

#
# The Array class is extened with a methods to allow keyword access 
#
  class Array
#{{{
    #
    # sets fields an dynamically extends this Array instance with methods for
    # keyword access
    #
    def fields=(*fields)
#{{{
      fields.flatten!
      raise ArgumentError, "no fields specified" if fields.empty?
      @fieldpos =
        fields.inject({}) do |h, f|
          unless String === f or Symbol === f
            raise ArgumentError, "<#{ f.inspect }> neither String nor Symbol"
          end
          h[f] = h.size
          h
        end
      extend ArrayFields unless defined? @fields
      @fields = fields
#}}}
    end
    #
    # access to field list
    #
    attr_reader :fields
    #
    # access to field mapping
    #
    attr_reader :fieldpos
#}}}
  end