require 'active_support/core_ext/hash/keys'
module ActiveSupport
# Implements a hash where keys <tt>:foo</tt> and <tt>"foo"</tt> are considered to be the same.
#
# rgb = ActiveSupport::HashWithIndifferentAccess.new
#
# rgb[:black] = '#000000'
# rgb[:black] # => '#000000'
# rgb['black'] # => '#000000'
#
# rgb['white'] = '#FFFFFF'
# rgb[:white] # => '#FFFFFF'
# rgb['white'] # => '#FFFFFF'
#
# Internally symbols are mapped to strings when used as keys in the entire
# writing interface (calling <tt>[]=</tt>, <tt>merge</tt>, etc). This
# mapping belongs to the public interface. For example, given
#
# hash = ActiveSupport::HashWithIndifferentAccess.new(:a => 1)
#
# you are guaranteed that the key is returned as a string:
#
# hash.keys # => ["a"]
#
# Technically other types of keys are accepted:
#
# hash = ActiveSupport::HashWithIndifferentAccess.new(:a => 1)
# hash[0] = 0
# hash # => {"a"=>1, 0=>0}
#
# but this class is intended for use cases where strings or symbols are the
# expected keys and it is convenient to understand both as the same. For
# example the +params+ hash in Ruby on Rails.
#
# Note that core extensions define <tt>Hash#with_indifferent_access</tt>:
#
# rgb = {:black => '#000000', :white => '#FFFFFF'}.with_indifferent_access
#
# which may be handy.
class HashWithIndifferentAccess < Hash
# Returns true so that <tt>Array#extract_options!</tt> finds members of
# this class.
def extractable_options?
true
end
def with_indifferent_access
dup
end
def nested_under_indifferent_access
self
end
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
def self.new_from_hash_copying_default(hash)
new(hash).tap do |new_hash|
new_hash.default = hash.default
end
end
def self.[](*args)
new.merge(Hash[*args])
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 = ActiveSupport::HashWithIndifferentAccess.new
# hash[:key] = "value"
#
# This value can be later fetched using either +:key+ or +"key"+.
def []=(key, value)
regular_writer(convert_key(key), convert_value(value))
end
alias_method :store, :[]=
# Updates the receiver in-place merging in the hash passed as argument:
#
# hash_1 = ActiveSupport::HashWithIndifferentAccess.new
# hash_2[:key] = "value"
#
# hash_2 = ActiveSupport::HashWithIndifferentAccess.new
# hash_2[:key] = "New Value!"
#
# hash_1.update(hash_2) # => {"key"=>"New Value!"}
#
# The argument can be either an
# <tt>ActiveSupport::HashWithIndifferentAccess</tt> or a regular +Hash+.
# In either case the merge respects the semantics of indifferent access.
#
# If the argument is a regular hash with keys +:key+ and +"key"+ only one
# of the values end up in the receiver, but which was is unespecified.
def update(other_hash)
if other_hash.is_a? HashWithIndifferentAccess
super(other_hash)
else
other_hash.each_pair { |key, value| regular_writer(convert_key(key), convert_value(value)) }
self
end
end
alias_method :merge!, :update
# Checks the hash for a key matching the argument passed in:
#
# hash = ActiveSupport::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?
# Same as <tt>Hash#fetch</tt> where the key passed as argument can be
# either a string or a symbol:
#
# counters = ActiveSupport::HashWithIndifferentAccess.new
# counters[:foo] = 1
#
# counters.fetch("foo") # => 1
# counters.fetch(:bar, 0) # => 0
# counters.fetch(:bar) {|key| 0} # => 0
# counters.fetch(:zoo) # => KeyError: key not found: "zoo"
#
def fetch(key, *extras)
super(convert_key(key), *extras)
end
# Returns an array of the values at the specified indices:
#
# hash = ActiveSupport::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
self.class.new(self).tap do |new_hash|
new_hash.default = default
end
end
# This method has the same semantics of +update+, except it does not
# modify the receiver but rather returns a new hash with indifferent
# access with the result of the merge.
def merge(hash)
self.dup.update(hash)
end
# Like +merge+ but the other way around: Merges the receiver into the
# argument and returns a new hash with indifferent access as result:
#
# hash = ActiveSupport::HashWithIndifferentAccess.new
# hash['a'] = nil
# hash.reverse_merge(:a => 0, :b => 1) # => {"a"=>nil, "b"=>1}
#
def reverse_merge(other_hash)
super(self.class.new_from_hash_copying_default(other_hash))
end
# Same semantics as +reverse_merge+ but modifies the receiver in-place.
def reverse_merge!(other_hash)
replace(reverse_merge( other_hash ))
end
# Removes the specified key from the hash.
def delete(key)
super(convert_key(key))
end
def stringify_keys!; self end
def deep_stringify_keys!; self end
def stringify_keys; dup end
def deep_stringify_keys; dup end
undef :symbolize_keys!
undef :deep_symbolize_keys!
def symbolize_keys; to_hash.symbolize_keys end
def deep_symbolize_keys; to_hash.deep_symbolize_keys end
def to_options!; self end
# Convert to a regular 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)
if value.is_a? Hash
value.nested_under_indifferent_access
elsif value.is_a?(Array)
value = value.dup if value.frozen?
value.map! { |e| convert_value(e) }
else
value
end
end
end
end
HashWithIndifferentAccess = ActiveSupport::HashWithIndifferentAccess
