module Hashie::Extensions::IndifferentAccess

def self.included(base) 

def self.included(base)
  base.class_eval do
    alias_method :regular_writer, :[]=
    alias_method :[]=, :indifferent_writer
    alias_method :store, :indifferent_writer
    %w(default update replace fetch delete key? values_at).each do |m|
      alias_method "regular_#{m}", m
      alias_method m, "indifferent_#{m}"
    end
    %w(include? member? has_key?).each do |key_alias|
      alias_method key_alias, :indifferent_key?
    end
    class << self
      def [](*)
        super.convert!
      end
      def try_convert(*)
        (hash = super) && self[hash]
      end
    end
  end
end

def self.inject(hash)

provided. See #inject!
Injects indifferent access into a duplicate of the hash 
def self.inject(hash)
  inject!(hash.dup)
end

def self.inject!(hash)

allows IndifferentAccess to spread to sub-hashes.
a hash without modifying the actual class. This is what
This will inject indifferent access into an instance of 
def self.inject!(hash)
  (class << hash; self; end).send :include, IndifferentAccess
  hash.convert!
end

def [](*) 

def [](*)
  super.convert!
end

def convert!

is injecting itself into member hashes.
their proper indifferent state. Used when IndifferentAccess
Iterates through the keys and values, reconverting them to 
def convert!
  keys.each do |k|
    regular_writer convert_key(k), convert_value(regular_delete(k))
  end
  self
end

def convert_key(key) 

def convert_key(key)
  key.to_s
end

def convert_value(value) 

def convert_value(value)
  if hash_lacking_indifference?(value)
    IndifferentAccess.inject(value.dup)
  elsif value.is_a?(::Array)
    value.dup.replace(value.map { |e| convert_value(e) })
  else
    value
  end
end

def hash_lacking_indifference?(other) 

def hash_lacking_indifference?(other)
  other.is_a?(::Hash) &&
  !(other.respond_to?(:indifferent_access?) &&
    other.indifferent_access?)
end

def hash_with_indifference?(other) 

def hash_with_indifference?(other)
  other.is_a?(::Hash) &&
  other.respond_to?(:indifferent_access?) &&
  other.indifferent_access?
end

def indifferent_access? 

def indifferent_access?
  true
end

def indifferent_default(key = nil) 

def indifferent_default(key = nil)
  return self[convert_key(key)] if key?(key)
  regular_default(key)
end

def indifferent_delete(key) 

def indifferent_delete(key)
  regular_delete convert_key(key)
end

def indifferent_fetch(key, *args) 

def indifferent_fetch(key, *args)
  regular_fetch convert_key(key), *args
end

def indifferent_key?(key) 

def indifferent_key?(key)
  regular_key? convert_key(key)
end

def indifferent_replace(other_hash) 

def indifferent_replace(other_hash)
  (keys - other_hash.keys).each { |key| delete(key) }
  other_hash.each { |key, value| self[key] = value }
  self
end

def indifferent_update(other_hash) 

def indifferent_update(other_hash)
  return regular_update(other_hash) if hash_with_indifference?(other_hash)
  other_hash.each_pair do |k, v|
    self[k] = v
  end
end

def indifferent_values_at(*indices) 

def indifferent_values_at(*indices)
  indices.map { |i| self[i] }
end

def indifferent_writer(key, value) 

def indifferent_writer(key, value)
  regular_writer convert_key(key), convert_value(value)
end

def try_convert(*) 

def try_convert(*)
  (hash = super) && self[hash]
end