/
hash.rb
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/
hash.rb
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module Virtus
class Attribute
# Hash
#
# @example
# class Post
# include Virtus
#
# attribute :meta, Hash
# end
#
# Post.new(:meta => { :tags => %w(foo bar) })
#
class Hash < Object
primitive ::Hash
coercion_method :to_hash
# The type to which keys of this hash will be coerced
#
# @example
#
# class Request
# include Virtus
#
# attribute :headers, Hash[Symbol => String]
# end
#
# Post.attributes[:headers].key_type # => Virtus::Attribute::Symbol
#
# @return [Virtus::Attribute]
#
# @api public
attr_reader :key_type
# The type to which values of this hash will be coerced
#
# @example
#
# class Request
# include Virtus
#
# attribute :headers, Hash[Symbol => String]
# end
#
# Post.attributes[:headers].value_type # => Virtus::Attribute::String
#
# @return [Virtus::Attribute]
#
# @api public
attr_reader :value_type
# Handles hashes with [key_type => value_type] syntax.
#
# @param [Class]
#
# @param [Hash]
#
# @return [Hash]
#
# @api private
def self.merge_options(type, options)
if !type.respond_to?(:size)
options
elsif type.size > 1
raise ArgumentError, "more than one [key => value] pair in `#{type.inspect}`"
else
options.merge(:key_type => type.keys.first, :value_type => type.values.first)
end
end
# Initializes an instance of {Virtus::Attribute::Hash}
#
# @api private
def initialize(*)
super
if @options.has_key?(:key_type) && @options.has_key?(:value_type)
@key_type = @options[:key_type]
@value_type = @options[:value_type]
@key_type_instance = Attribute.build(@name, @key_type)
@value_type_instance = Attribute.build(@name, @value_type)
end
end
# Coerce a hash with keys and values
#
# @param [Object]
#
# @return [Object]
#
# @api private
def coerce(value)
coerced = super
return coerced unless coerced.respond_to?(:inject)
coerced.inject(new_hash) do |hash, key_and_value|
hash[key_and_value[0]] = key_and_value[1]
hash
end
end
# Return an instance of the Hash with redefined []= method to coerce
# keys and values on assigning.
#
# @return [Hash]
#
# @api private
def new_hash
hash = self.class.primitive.new
return hash unless @key_type_instance && @value_type_instance
key_coercion_method = @key_type_instance.coercion_method
value_coercion_method = @value_type_instance.coercion_method
# Redefine []= method to coerce key and value on assigning.
# It requires inlining of Attribute#coerce method to coerce.
# An alternative way would be using define_singleton_method or Sinatra's meta_def.
hash.instance_eval(<<-eorb, __FILE__, __LINE__+1)
def []=(key, value) # def []=(key, value)
coerced_key = Virtus::Coercion[key.class].#{key_coercion_method}(key) # coerced_key = Virtus::Coercion[key.class].to_sym(key)
coerced_value = Virtus::Coercion[value.class].#{value_coercion_method}(value) # coerced_value = Virtus::Coercion[value.class].to_f(value)
super(coerced_key, coerced_value) # super(coerce_key, coerce_value)
end # end
eorb
hash
end
end # class Hash
end # class Attribute
end # module Virtus