instiki/vendor/rails/activesupport/lib/active_support/core_ext/hash/indifferent_access.rb

# This class has dubious semantics and we only have it so that
# people can write params[:key] instead of params['key']
# and they get the same value for both keys.

class HashWithIndifferentAccess < Hash
  def initialize(constructor = {})
    if constructor.is_a?(Hash)
      super()
      update(constructor)
    else
      super(constructor)
    end
  end

  def default(key = nil)
    if key.is_a?(Symbol) && include?(key = key.to_s)
      self[key]
    else
      super
    end
  end

  alias_method :regular_writer, :[]= unless method_defined?(:regular_writer)
  alias_method :regular_update, :update unless method_defined?(:regular_update)

  # Assigns a new value to the hash:
  #
  #   hash = HashWithIndifferentAccess.new
  #   hash[:key] = "value"
  #
  def []=(key, value)
    regular_writer(convert_key(key), convert_value(value))
  end

  # Updates the instantized hash with values from the second:
  # 
  #   hash_1 = HashWithIndifferentAccess.new
  #   hash_1[:key] = "value"
  # 
  #   hash_2 = HashWithIndifferentAccess.new
  #   hash_2[:key] = "New Value!"
  # 
  #   hash_1.update(hash_2) # => {"key"=>"New Value!"}
  # 
  def update(other_hash)
    other_hash.each_pair { |key, value| regular_writer(convert_key(key), convert_value(value)) }
    self
  end

  alias_method :merge!, :update

  # Checks the hash for a key matching the argument passed in:
  #
  #   hash = HashWithIndifferentAccess.new
  #   hash["key"] = "value"
  #   hash.key? :key  # => true
  #   hash.key? "key" # => true
  #
  def key?(key)
    super(convert_key(key))
  end

  alias_method :include?, :key?
  alias_method :has_key?, :key?
  alias_method :member?, :key?

  # Fetches the value for the specified key, same as doing hash[key]
  def fetch(key, *extras)
    super(convert_key(key), *extras)
  end

  # Returns an array of the values at the specified indices:
  #
  #   hash = HashWithIndifferentAccess.new
  #   hash[:a] = "x"
  #   hash[:b] = "y"
  #   hash.values_at("a", "b") # => ["x", "y"]
  #
  def values_at(*indices)
    indices.collect {|key| self[convert_key(key)]}
  end

  # Returns an exact copy of the hash.
  def dup
    HashWithIndifferentAccess.new(self)
  end

  # Merges the instantized and the specified hashes together, giving precedence to the values from the second hash
  # Does not overwrite the existing hash.
  def merge(hash)
    self.dup.update(hash)
  end

  # Performs the opposite of merge, with the keys and values from the first hash taking precedence over the second.
  # This overloaded definition prevents returning a regular hash, if reverse_merge is called on a HashWithDifferentAccess.
  def reverse_merge(other_hash)
    super other_hash.with_indifferent_access
  end

  # Removes a specified key from the hash.
  def delete(key)
    super(convert_key(key))
  end

  def stringify_keys!; self end
  def symbolize_keys!; self end
  def to_options!; self end

  # Convert to a Hash with String keys.
  def to_hash
    Hash.new(default).merge(self)
  end

  protected
    def convert_key(key)
      key.kind_of?(Symbol) ? key.to_s : key
    end

    def convert_value(value)
      case value
      when Hash
        value.with_indifferent_access
      when Array
        value.collect { |e| e.is_a?(Hash) ? e.with_indifferent_access : e }
      else
        value
      end
    end
end

module ActiveSupport #:nodoc:
  module CoreExtensions #:nodoc:
    module Hash #:nodoc:
      module IndifferentAccess #:nodoc:
        def with_indifferent_access
          hash = HashWithIndifferentAccess.new(self)
          hash.default = self.default
          hash
        end
      end
    end
  end
end