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b16eaf8632
Patch by Yuuji Yaginuma. [Fixes GH-1808] In other classes, `FrozenError` will be raised if change the frozen object. In order to match the behavior, I think that `FrozenError` should use in `OpenStruct`. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62271 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
368 lines
10 KiB
Ruby
368 lines
10 KiB
Ruby
# frozen_string_literal: true
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#
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# = ostruct.rb: OpenStruct implementation
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#
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# Author:: Yukihiro Matsumoto
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# Documentation:: Gavin Sinclair
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#
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# OpenStruct allows the creation of data objects with arbitrary attributes.
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# See OpenStruct for an example.
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#
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#
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# An OpenStruct is a data structure, similar to a Hash, that allows the
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# definition of arbitrary attributes with their accompanying values. This is
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# accomplished by using Ruby's metaprogramming to define methods on the class
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# itself.
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#
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# == Examples
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#
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# require "ostruct"
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#
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# person = OpenStruct.new
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# person.name = "John Smith"
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# person.age = 70
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#
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# person.name # => "John Smith"
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# person.age # => 70
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# person.address # => nil
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#
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# An OpenStruct employs a Hash internally to store the attributes and values
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# and can even be initialized with one:
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#
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# australia = OpenStruct.new(:country => "Australia", :capital => "Canberra")
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# # => #<OpenStruct country="Australia", capital="Canberra">
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#
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# Hash keys with spaces or characters that could normally not be used for
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# method calls (e.g. <code>()[]*</code>) will not be immediately available
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# on the OpenStruct object as a method for retrieval or assignment, but can
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# still be reached through the Object#send method.
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#
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# measurements = OpenStruct.new("length (in inches)" => 24)
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# measurements.send("length (in inches)") # => 24
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#
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# message = OpenStruct.new(:queued? => true)
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# message.queued? # => true
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# message.send("queued?=", false)
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# message.queued? # => false
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#
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# Removing the presence of an attribute requires the execution of the
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# delete_field method as setting the property value to +nil+ will not
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# remove the attribute.
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#
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# first_pet = OpenStruct.new(:name => "Rowdy", :owner => "John Smith")
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# second_pet = OpenStruct.new(:name => "Rowdy")
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#
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# first_pet.owner = nil
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# first_pet # => #<OpenStruct name="Rowdy", owner=nil>
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# first_pet == second_pet # => false
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#
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# first_pet.delete_field(:owner)
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# first_pet # => #<OpenStruct name="Rowdy">
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# first_pet == second_pet # => true
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#
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#
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# == Implementation
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#
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# An OpenStruct utilizes Ruby's method lookup structure to find and define the
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# necessary methods for properties. This is accomplished through the methods
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# method_missing and define_singleton_method.
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#
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# This should be a consideration if there is a concern about the performance of
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# the objects that are created, as there is much more overhead in the setting
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# of these properties compared to using a Hash or a Struct.
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#
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class OpenStruct
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#
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# Creates a new OpenStruct object. By default, the resulting OpenStruct
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# object will have no attributes.
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#
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# The optional +hash+, if given, will generate attributes and values
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# (can be a Hash, an OpenStruct or a Struct).
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# For example:
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#
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# require "ostruct"
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# hash = { "country" => "Australia", :capital => "Canberra" }
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# data = OpenStruct.new(hash)
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#
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# data # => #<OpenStruct country="Australia", capital="Canberra">
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#
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def initialize(hash=nil)
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@table = {}
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if hash
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hash.each_pair do |k, v|
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k = k.to_sym
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@table[k] = v
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end
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end
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end
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# Duplicates an OpenStruct object's Hash table.
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def initialize_copy(orig) # :nodoc:
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super
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@table = @table.dup
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end
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#
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# Converts the OpenStruct to a hash with keys representing
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# each attribute (as symbols) and their corresponding values.
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#
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# require "ostruct"
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# data = OpenStruct.new("country" => "Australia", :capital => "Canberra")
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# data.to_h # => {:country => "Australia", :capital => "Canberra" }
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#
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def to_h
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@table.dup
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end
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#
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# :call-seq:
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# ostruct.each_pair {|name, value| block } -> ostruct
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# ostruct.each_pair -> Enumerator
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#
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# Yields all attributes (as symbols) along with the corresponding values
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# or returns an enumerator if no block is given.
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#
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# require "ostruct"
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# data = OpenStruct.new("country" => "Australia", :capital => "Canberra")
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# data.each_pair.to_a # => [[:country, "Australia"], [:capital, "Canberra"]]
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#
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def each_pair
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return to_enum(__method__) { @table.size } unless block_given?
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@table.each_pair{|p| yield p}
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self
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end
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#
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# Provides marshalling support for use by the Marshal library.
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#
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def marshal_dump
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@table
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end
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#
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# Provides marshalling support for use by the Marshal library.
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#
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def marshal_load(x)
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@table = x
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end
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#
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# Used internally to check if the OpenStruct is able to be
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# modified before granting access to the internal Hash table to be modified.
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#
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def modifiable? # :nodoc:
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begin
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@modifiable = true
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rescue
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raise FrozenError, "can't modify frozen #{self.class}", caller(3)
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end
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@table
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end
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private :modifiable?
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# ::Kernel.warn("do not use OpenStruct#modifiable", uplevel: 1)
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alias modifiable modifiable? # :nodoc:
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protected :modifiable
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#
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# Used internally to defined properties on the
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# OpenStruct. It does this by using the metaprogramming function
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# define_singleton_method for both the getter method and the setter method.
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#
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def new_ostruct_member!(name) # :nodoc:
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name = name.to_sym
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unless singleton_class.method_defined?(name)
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define_singleton_method(name) { @table[name] }
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define_singleton_method("#{name}=") {|x| modifiable?[name] = x}
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end
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name
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end
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private :new_ostruct_member!
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# ::Kernel.warn("do not use OpenStruct#new_ostruct_member", uplevel: 1)
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alias new_ostruct_member new_ostruct_member! # :nodoc:
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protected :new_ostruct_member
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def freeze
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@table.each_key {|key| new_ostruct_member!(key)}
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super
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end
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def respond_to_missing?(mid, include_private = false) # :nodoc:
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mname = mid.to_s.chomp("=").to_sym
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@table&.key?(mname) || super
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end
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def method_missing(mid, *args) # :nodoc:
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len = args.length
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if mname = mid[/.*(?==\z)/m]
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if len != 1
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raise ArgumentError, "wrong number of arguments (#{len} for 1)", caller(1)
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end
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modifiable?[new_ostruct_member!(mname)] = args[0]
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elsif len == 0 # and /\A[a-z_]\w*\z/ =~ mid #
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if @table.key?(mid)
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new_ostruct_member!(mid) unless frozen?
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@table[mid]
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end
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else
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begin
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super
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rescue NoMethodError => err
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err.backtrace.shift
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raise
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end
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end
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end
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#
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# :call-seq:
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# ostruct[name] -> object
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#
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# Returns the value of an attribute.
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#
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# require "ostruct"
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# person = OpenStruct.new("name" => "John Smith", "age" => 70)
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# person[:age] # => 70, same as person.age
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#
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def [](name)
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@table[name.to_sym]
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end
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#
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# :call-seq:
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# ostruct[name] = obj -> obj
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#
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# Sets the value of an attribute.
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#
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# require "ostruct"
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# person = OpenStruct.new("name" => "John Smith", "age" => 70)
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# person[:age] = 42 # equivalent to person.age = 42
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# person.age # => 42
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#
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def []=(name, value)
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modifiable?[new_ostruct_member!(name)] = value
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end
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#
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# :call-seq:
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# ostruct.dig(name, ...) -> object
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#
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# Extracts the nested value specified by the sequence of +name+
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# objects by calling +dig+ at each step, returning +nil+ if any
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# intermediate step is +nil+.
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#
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# require "ostruct"
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# address = OpenStruct.new("city" => "Anytown NC", "zip" => 12345)
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# person = OpenStruct.new("name" => "John Smith", "address" => address)
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#
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# person.dig(:address, "zip") # => 12345
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# person.dig(:business_address, "zip") # => nil
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#
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# data = OpenStruct.new(:array => [1, [2, 3]])
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#
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# data.dig(:array, 1, 0) # => 2
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# data.dig(:array, 0, 0) # TypeError: Integer does not have #dig method
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#
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def dig(name, *names)
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begin
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name = name.to_sym
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rescue NoMethodError
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raise TypeError, "#{name} is not a symbol nor a string"
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end
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@table.dig(name, *names)
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end
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#
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# Removes the named field from the object. Returns the value that the field
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# contained if it was defined.
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#
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# require "ostruct"
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#
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# person = OpenStruct.new(name: "John", age: 70, pension: 300)
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#
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# person.delete_field("age") # => 70
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# person # => #<OpenStruct name="John", pension=300>
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#
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# Setting the value to +nil+ will not remove the attribute:
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#
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# person.pension = nil
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# person # => #<OpenStruct name="John", pension=nil>
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#
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def delete_field(name)
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sym = name.to_sym
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begin
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singleton_class.__send__(:remove_method, sym, "#{sym}=")
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rescue NameError
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end
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@table.delete(sym) do
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raise NameError.new("no field `#{sym}' in #{self}", sym)
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end
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end
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InspectKey = :__inspect_key__ # :nodoc:
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#
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# Returns a string containing a detailed summary of the keys and values.
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#
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def inspect
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ids = (Thread.current[InspectKey] ||= [])
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if ids.include?(object_id)
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detail = ' ...'
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else
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ids << object_id
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begin
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detail = @table.map do |key, value|
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" #{key}=#{value.inspect}"
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end.join(',')
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ensure
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ids.pop
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end
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end
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['#<', self.class, detail, '>'].join
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end
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alias :to_s :inspect
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attr_reader :table # :nodoc:
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protected :table
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alias table! table
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#
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# Compares this object and +other+ for equality. An OpenStruct is equal to
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# +other+ when +other+ is an OpenStruct and the two objects' Hash tables are
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# equal.
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#
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# require "ostruct"
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# first_pet = OpenStruct.new("name" => "Rowdy")
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# second_pet = OpenStruct.new(:name => "Rowdy")
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# third_pet = OpenStruct.new("name" => "Rowdy", :age => nil)
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#
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# first_pet == second_pet # => true
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# first_pet == third_pet # => false
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#
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def ==(other)
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return false unless other.kind_of?(OpenStruct)
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@table == other.table!
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end
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#
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# Compares this object and +other+ for equality. An OpenStruct is eql? to
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# +other+ when +other+ is an OpenStruct and the two objects' Hash tables are
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# eql?.
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#
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def eql?(other)
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return false unless other.kind_of?(OpenStruct)
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@table.eql?(other.table!)
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end
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# Computes a hash code for this OpenStruct.
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# Two OpenStruct objects with the same content will have the same hash code
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# (and will compare using #eql?).
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#
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# See also Object#hash.
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def hash
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@table.hash
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end
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end
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