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[Feature #16993] Introduce Hash#keys_to_set #40

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[Feature #16993] Introduce Hash#keys_to_set #40

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13 changes: 13 additions & 0 deletions lib/set.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -852,4 +852,17 @@ def to_set(klass = Set, *args, &block)
end unless method_defined?(:to_set)
end

class Hash
# Returns a new Set containing keys from the Hash
#
# h = {a: 1, b: 3}
# h.keys_to_set #=> Set[:a, :b]
#
def keys_to_set
set = Set.new
set.instance_variable_set(:@hash, transform_values { true })
set
end
end

autoload :SortedSet, "#{__dir__}/set/sorted_set"
10 changes: 10 additions & 0 deletions test/test_set.rb
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Expand Up @@ -857,6 +857,16 @@ def test_to_set
end
end

class TC_Hash < Test::Unit::TestCase
def test_keys_to_set
h = {a: 2, b: 1, c: 37}
set = h.keys_to_set
expected = Set.new(h.keys)

assert_equal(set, expected)
end
end

class TC_Set_Builtin < Test::Unit::TestCase
private def should_omit?
(RUBY_VERSION.scan(/\d+/).map(&:to_i) <=> [3, 2]) < 0 ||
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