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rails--rails/activesupport/lib/active_support/ordered_hash.rb
2012-05-16 14:44:57 -05:00

40 lines
1 KiB
Ruby

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 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