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|
class Array
# Expected to be an enumeration of arrays. This method
# iterates through combinations of each in position.
# It produces an array of arrays of all possible combinations
# of the given arrays in the positions given. (Imagine
# it like a slot machine dial. This gives every combination
# that could come up.)
#
# a = [ [0,1], [2,3] ]
# a.combo{ |c| p c }
#
# produces
#
# [0, 2]
# [0, 3]
# [1, 2]
# [1, 3]
#
# CREDIT: Trans
def combo(&block)
if block_given?
a = collect{ |x|
x.respond_to?(:to_a) ? x.to_a : 0..x
}
if a.size == 1
r = a.shift
r.each{ |n|
yield n
}
else
r = a.shift
r.each{ |n|
a.each_combo{ |s|
yield [n, *s]
}
}
end
else
to_enum(:combo)
end
end
end
|
