aboutsummaryrefslogblamecommitdiffstats
path: root/activesupport/lib/active_support/ordered_hash.rb
blob: 58a2ce2105d44d2ea8278805cee33559354ae14c (plain) (tree)
1
2
3
4
5
6
7
8
9

              
                                            
                                                         

   
                    

                                                                        
   



                                                     
   





                                                                          
                            

                               
       
 



                                                           
                             
                                                    

       



                                       



                                                                                                 
     
   
require 'yaml'

YAML.add_builtin_type("omap") do |type, val|
  ActiveSupport::OrderedHash[val.map{ |v| v.to_a.first }]
end

module ActiveSupport
  # <tt>ActiveSupport::OrderedHash</tt> implements a hash that preserves
  # insertion order.
  #
  #   oh = ActiveSupport::OrderedHash.new
  #   oh[:a] = 1
  #   oh[:b] = 2
  #   oh.keys # => [:a, :b], this order is guaranteed
  #
  # Also, maps the +omap+ feature for YAML files
  # (See http://yaml.org/type/omap.html) to support ordered items
  # when loading from yaml.
  #
  # <tt>ActiveSupport::OrderedHash</tt> is namespaced to prevent conflicts
  # with other implementations.
  class OrderedHash < ::Hash
    def to_yaml_type
      "!tag:yaml.org,2002:omap"
    end

    def encode_with(coder)
      coder.represent_seq '!omap', map { |k,v| { k => v } }
    end

    def reject(*args, &block)
      dup.tap { |hash| hash.reject!(*args, &block) }
    end

    def nested_under_indifferent_access
      self
    end

    # Returns true to make sure that this hash is extractable via <tt>Array#extract_options!</tt>
    def extractable_options?
      true
    end
  end
end