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# frozen_string_literal: true
module Roadie
module Rails
module Utils
module_function
# Combine two hashes, or return the non-nil hash if either is nil.
# Returns nil if both are nil.
def combine_hash(first, second)
combine_nilable(first, second) do |a, b|
a.merge(b)
end
end
# Return a callable that will call both inputs. If either is nil, then
# just return the other.
#
# The result from the second one will be the result of the combined
# callable.
#
# ```ruby
# combine_callable(-> { 1 }, -> { 2 }).call # => 2
# combine_callable(-> { 1 }, nil).call # => 1
# combine_callable(nil, nil).nil? # => true
# ```
def combine_callable(first, second)
combine_nilable(first, second) do |a, b|
lambda do |*args|
a.call(*args)
b.call(*args)
end
end
end
# Combine two Provider ducks into a ProviderList. If either is nil, pick
# the non-nil value instead.
def combine_providers(first, second)
combine_nilable(first, second) do |a, b|
ProviderList.new(a.to_a + Array.wrap(b))
end
end
# Discard the nil value. If neither is nil, then yield both and return
# the result from the block.
#
# ```ruby
# combine_nilable(nil, 5) { |a, b| a+b } # => 5
# combine_nilable(7, nil) { |a, b| a+b } # => 7
# combine_nilable(nil, nil) { |a, b| a+b } # => nil
# combine_nilable(7, 5) { |a, b| a+b } # => 12
# ```
def combine_nilable(first, second)
if first && second
yield first, second
else
first || second
end
end
end
end
end
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