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Contents
# frozen_string_literal: true
module Enumerable
# Produces a array with values's all combinations.
#
# Example:
# %i[a b].boolean_combinations
# => [[], [:a], [:b], [:a, :b]]
#
# @return [Array]
def bool_array_combs
bool_combs([], method(:bool_array_combs_new_comb))
end
# Produces a hash with values's all combinations.
#
# Example:
# %i[a b].boolean_combinations
# => [{a: false, b: false}, {a: false, b: true}, {a: true, b: false}, {a: true, b: true}]
#
# @return [Hash]
def bool_hash_combs
bool_combs({}, method(:bool_hash_combs_new_comb))
end
private
def bool_combs(empty_value, new_comb_method)
head = [empty_value]
r = inject(head) do |a, value|
new_comb_method.call(value, a)
end
r == head ? [] : r
end
def bool_array_combs_new_comb(value, combs)
combs + combs.map { |c| c + [value] }
end
def bool_hash_combs_new_comb(value, combs)
combs.flat_map do |comb|
[false, true].map { |bool_value| comb.dup.merge(value => bool_value) }
end
end
end
Version data entries
376 entries across 376 versions & 4 rubygems