diff options
Diffstat (limited to 'activesupport/lib/active_support/core_ext/enumerable.rb')
| -rw-r--r-- | activesupport/lib/active_support/core_ext/enumerable.rb | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/core_ext/enumerable.rb b/activesupport/lib/active_support/core_ext/enumerable.rb new file mode 100644 index 0000000000..d87d63f287 --- /dev/null +++ b/activesupport/lib/active_support/core_ext/enumerable.rb @@ -0,0 +1,168 @@ +# frozen_string_literal: true + +module Enumerable + INDEX_WITH_DEFAULT = Object.new + private_constant :INDEX_WITH_DEFAULT + + # Enumerable#sum was added in Ruby 2.4, but it only works with Numeric elements + # when we omit an identity. + + # :stopdoc: + + # We can't use Refinements here because Refinements with Module which will be prepended + # doesn't work well https://bugs.ruby-lang.org/issues/13446 + alias :_original_sum_with_required_identity :sum + private :_original_sum_with_required_identity + + # :startdoc: + + # Calculates a sum from the elements. + # + # payments.sum { |p| p.price * p.tax_rate } + # payments.sum(&:price) + # + # The latter is a shortcut for: + # + # payments.inject(0) { |sum, p| sum + p.price } + # + # It can also calculate the sum without the use of a block. + # + # [5, 15, 10].sum # => 30 + # ['foo', 'bar'].sum # => "foobar" + # [[1, 2], [3, 1, 5]].sum # => [1, 2, 3, 1, 5] + # + # The default sum of an empty list is zero. You can override this default: + # + # [].sum(Payment.new(0)) { |i| i.amount } # => Payment.new(0) + def sum(identity = nil, &block) + if identity + _original_sum_with_required_identity(identity, &block) + elsif block_given? + map(&block).sum(identity) + else + inject(:+) || 0 + end + end + + # Convert an enumerable to a hash keying it by the block return value. + # + # people.index_by(&:login) + # # => { "nextangle" => <Person ...>, "chade-" => <Person ...>, ...} + # + # people.index_by { |person| "#{person.first_name} #{person.last_name}" } + # # => { "Chade- Fowlersburg-e" => <Person ...>, "David Heinemeier Hansson" => <Person ...>, ...} + def index_by + if block_given? + result = {} + each { |elem| result[yield(elem)] = elem } + result + else + to_enum(:index_by) { size if respond_to?(:size) } + end + end + + # Convert an enumerable to a hash keying it with the enumerable items and with the values returned in the block. + # + # post = Post.new(title: "hey there", body: "what's up?") + # + # %i( title body ).index_with { |attr_name| post.public_send(attr_name) } + # # => { title: "hey there", body: "what's up?" } + def index_with(default = INDEX_WITH_DEFAULT) + if block_given? + result = {} + each { |elem| result[elem] = yield(elem) } + result + elsif default != INDEX_WITH_DEFAULT + result = {} + each { |elem| result[elem] = default } + result + else + to_enum(:index_with) { size if respond_to?(:size) } + end + end + + # Returns +true+ if the enumerable has more than 1 element. Functionally + # equivalent to <tt>enum.to_a.size > 1</tt>. Can be called with a block too, + # much like any?, so <tt>people.many? { |p| p.age > 26 }</tt> returns +true+ + # if more than one person is over 26. + def many? + cnt = 0 + if block_given? + any? do |element| + cnt += 1 if yield element + cnt > 1 + end + else + any? { (cnt += 1) > 1 } + end + end + + # The negative of the <tt>Enumerable#include?</tt>. Returns +true+ if the + # collection does not include the object. + def exclude?(object) + !include?(object) + end + + # Returns a copy of the enumerable without the specified elements. + # + # ["David", "Rafael", "Aaron", "Todd"].without "Aaron", "Todd" + # # => ["David", "Rafael"] + # + # {foo: 1, bar: 2, baz: 3}.without :bar + # # => {foo: 1, baz: 3} + def without(*elements) + reject { |element| elements.include?(element) } + end + + # Convert an enumerable to an array based on the given key. + # + # [{ name: "David" }, { name: "Rafael" }, { name: "Aaron" }].pluck(:name) + # # => ["David", "Rafael", "Aaron"] + # + # [{ id: 1, name: "David" }, { id: 2, name: "Rafael" }].pluck(:id, :name) + # # => [[1, "David"], [2, "Rafael"]] + def pluck(*keys) + if keys.many? + map { |element| keys.map { |key| element[key] } } + else + map { |element| element[keys.first] } + end + end +end + +class Range #:nodoc: + # Optimize range sum to use arithmetic progression if a block is not given and + # we have a range of numeric values. + def sum(identity = nil) + if block_given? || !(first.is_a?(Integer) && last.is_a?(Integer)) + super + else + actual_last = exclude_end? ? (last - 1) : last + if actual_last >= first + sum = identity || 0 + sum + (actual_last - first + 1) * (actual_last + first) / 2 + else + identity || 0 + end + end + end +end + +# Using Refinements here in order not to expose our internal method +using Module.new { + refine Array do + alias :orig_sum :sum + end +} + +class Array #:nodoc: + # Array#sum was added in Ruby 2.4 but it only works with Numeric elements. + def sum(init = nil, &block) + if init.is_a?(Numeric) || first.is_a?(Numeric) + init ||= 0 + orig_sum(init, &block) + else + super + end + end +end |