#-------------------------------------------------------------------------
# 
# Open Source License/Disclaimer, Forecast Systems Laboratory NOAA/OAR/FSL, 
# 325 Broadway Boulder, CO 80305
# 
# This software is distributed under the Open Source Definition, which may 
# be found at http://www.opensource.org/osd.html.
# 
# In particular, redistribution and use in source and binary forms, with or 
# without modification, are permitted provided that the following conditions
# are met:
# 
#     . Redistributions of source code must retain this notice, this list 
#     of conditions and the following disclaimer. 
# 
#     . Redistributions in binary form must provide access to this notice,
#     this list of conditions and the following disclaimer, and the 
#     underlying source code. 
# 
#     . All modifications to this software must be clearly documented, and
#     are solely the responsibility of the agent making the modifications. 
# 
#     . If significant modifications or enhancements are made to this 
#     software, the FSL Software Policy Manager (softwaremgr@fsl.noaa.gov)
#     should be notified. 
# 
#-------------------------------------------------------------------------
# 
# THIS SOFTWARE AND ITS DOCUMENTATION ARE IN THE PUBLIC DOMAIN AND ARE 
# FURNISHED "AS IS." THE AUTHORS, THE UNITED STATES GOVERNMENT, ITS 
# INSTRUMENTALITIES, OFFICERS, EMPLOYEES, AND AGENTS MAKE NO WARRANTY, 
# EXPRESS OR IMPLIED, AS TO THE USEFULNESS OF THE SOFTWARE AND DOCUMENTATION 
# FOR ANY PURPOSE. THEY ASSUME NO RESPONSIBILITY (1) FOR THE USE OF THE
# SOFTWARE AND DOCUMENTATION; OR (2) TO PROVIDE TECHNICAL SUPPORT TO USERS.
# 
#-------------------------------------------------------------------------
# 
#
# WARNING: This is OPAQUE Facility Division (FD) Software. All OPAQUE FD 
# Software is subject to change without notice.


# The ArrayFields module implements methods which allow an Array's fields to
# be indexed by name (String).  This is incredibly usefull for naming the
# fields of tuples (Arrays) returned from database queries

module ArrayFields 
  # given one, more field names, returns those elements
  def [] (*idx)
    idx.flatten!
    return self.indices(*idx) if idx.size > 1
    idx = idx[0]
    if @fields and idx.type == String
      pos = @fieldpos[idx]
      return nil unless pos
      self[pos]
    else
      super
    end
  end
  # given one field name, assign value to this field
  def []= idx, value 
    if @fields and idx.type == String
      pos = @fieldpos[idx]
      if not pos
	pos = size
	@fieldpos[idx] = pos
      end
      self[pos] = value
    else
      super
    end
  end
  # given one, more field names, returns those elements
  def indices(*idxs)
    idxs.flatten!
    if @fields
      idxs.collect! do |idx|
	idx.type == String ? @fieldpos[idx] : idx
      end
    end
    super(*idxs)
  end
end

# The array class is extened here with a methods which dynamically include
# ArrayFields, allowing access to fields by name, when the methods fields= is
# called
class Array
  # when this method is called, extends this Array object such that it's
  # fields will be accessible as those in fields.  a copy of fields is NOT
  # taken for efficiency so make your own copy of you plan to modify it! 
  #
  # a = ['ford', 42]
  # a.fields = ['name', 'number']
  # p a['name'] # >> 'ford'
  def fields= fields
    @recursive_fields = true unless defined? @recursive_fields
    each{|e| e.fields = fields if recursive_fields && Array === e}
    extend ArrayFields unless @fields
    @fields = fields # not a copy!
    @fieldpos = Hash.new
    @fields.each_with_index {|f,i| @fieldpos[f] = i}
  end
  attr_reader :fields
  attr_reader :fieldpos
  attr :recursive_fields, true
end

if $0 == __FILE__
  fields = ['zero','one','two']
  a = [0,1,2]
  a.fields = fields 

  fields.each{|f| puts "a[#{f}]\t\t:\t\t#{a[f]}"} 

  puts a[fields]
  puts a[fields.reverse]

  b = a.clone
  fields.each{|f| puts "b[#{f}]\t\t:\t\t#{b[f]}"} 

  table = 
  [
    ['ryan',6.3],
    ['ahoward',5.11],
  ]

  table.fields = ['name','height']

  puts table[0]['name']
  puts table[0]['height']
  puts table[1]['name']
  puts table[1]['height']

  #puts table[0]['name','height']

  puts table[0][['name','height']] 
  puts table[0]['name','height'] 
  puts table[0].indices 'name','height'
  puts table[0].indices ['name','height']
end