path: root/lib/ohai/mash.rb

# Copyright (c) 2009 Dan Kubb

# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# ---
# ---

# Some portions of blank.rb and mash.rb are verbatim copies of software
# licensed under the MIT license. That license is included below:

# Copyright (c) 2005-2008 David Heinemeier Hansson

# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:

# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# This class has dubious semantics and we only have it so that people can write
# params[:key] instead of params['key'].
class Mash < Hash

  # @param constructor [Object] The default value for the mash.
  # If constructor is a Hash, a new mash will be created based on the keys of the hash and
  # no default value will be set.
  def initialize(constructor = {})
    if constructor.is_a?(Hash)
      super()
      update(constructor)
    else
      super(constructor)
    end
  end

  # @param key [Object] The default value for the mash.
  # If key is a Symbol and it is a key in the mash, then the default value will be set to
  # the value matching the key.
  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)

  # @param key [Object] The key to set.
  # @param value [Object] The value to set the key to.
  #
  # @see Mash#convert_key
  # @see Mash#convert_value
  def []=(key, value)
    regular_writer(convert_key(key), convert_value(value))
  end

  # @param other_hash [Hash]
  #   A hash to update values in the mash with. The keys and the values will be
  #   converted to Mash format.
  #
  # @return [Mash] The updated mash.
  def update(other_hash)
    other_hash.each_pair { |key, value| regular_writer(convert_key(key), convert_value(value)) }
    self
  end

  alias_method :merge!, :update

  # @param key [Object] The key to check for. This will be run through convert_key.
  #
  # @return [Boolean] True if the key exists in the mash.
  def key?(key)
    super(convert_key(key))
  end

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

  # @param key [Object] The key to fetch. This will be run through convert_key.
  # @param extras [Array] Default value.
  #
  # @return [Object] The value at key or the default value.
  def fetch(key, *extras)
    super(convert_key(key), *extras)
  end

  # @param indices [Array] The keys to retrieve values for. These will be run through +convert_key+.
  #
  # @return [Array] The values at each of the provided keys
  def values_at(*indices)
    indices.collect { |key| self[convert_key(key)] }
  end

  # @param hash [Hash] The hash to merge with the mash.
  #
  # @return [Mash] A new mash with the hash values merged in.
  def merge(hash)
    dup.update(hash)
  end

  # @param key [Object] The key to delete from the mash.
  def delete(key)
    super(convert_key(key))
  end

  # @param keys [Array<String, Symbol>] The mash keys to exclude.
  #
  # @return [Mash] A new mash without the selected keys.
  #
  # @example
  #   { :one => 1, :two => 2, :three => 3 }.except(:one)
  #     #=> { "two" => 2, "three" => 3 }
  def except(*keys)
    super(*keys.map { |k| convert_key(k) })
  end

  # Used to provide the same interface as Hash.
  #
  # @return [Mash] This mash unchanged.
  def stringify_keys!; self end

  # @return [Hash] The mash as a Hash with symbolized keys.
  def symbolize_keys
    h = Hash.new(default)
    each { |key, val| h[key.to_sym] = val }
    h
  end

  # @return [Hash] The mash as a Hash with string keys.
  def to_hash
    Hash.new(default).merge(self)
  end

  # Convert a Hash into a Mash. The input Hash's default value is maintained
  # @return [Mash]
  def self.from_hash(hash)
    mash = Mash.new(hash)
    mash.default = hash.default
    mash
  end

  protected

  # @param key [Object] The key to convert.
  # @return [Object] The converted key. If the key was a symbol, it will be converted to a string.
  #
  # @api private
  def convert_key(key)
    key.is_a?(Symbol) ? key.to_s : key
  end

  # @param value [Object] The value to convert.
  #
  # @return [Object]
  #   The converted value. A Hash or an Array of hashes, will be converted to
  #   their Mash equivalents.
  #
  # @api private
  def convert_value(value)
    if value.class == Hash
      Mash.from_hash(value)
    elsif value.is_a?(Array)
      value.collect { |e| convert_value(e) }
    else
      value
    end
  end
end