Generates all possible combinations of a set, including doubles, to fill given spaces on a string

genpass.rb

##############################################
#             genpass.rb                     #
#         Generates a table of possible      #
#     passwords according to a fixed pattern #
#                                            #
#             Ugly, but works                #
##############################################

def generate_combinations(array, r)
    n = array.length
    indices = (0...r).to_a
    final = (n - r...n).to_a
    while indices != final
        yield indices.map {|k| array[k]}
        i = r - 1
        while indices[i] == n - r + i
            i -= 1
        end
        indices[i] += 1
        (i + 1...r).each do |j|
            indices[j] = indices[i] + j - i
        end
    end
    yield indices.map {|k| array[k]}
end

# Our character space, add or remove as you need
all = ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z']

(1..2).each do |i| # Change this interval
    (1..2).each do |j| # And this
        generate_combinations(all * i, i) do |g|
            generate_combinations(all * j, j) do |h|
                # Change this string according to your pattern
                puts "(#{g.pack("a"*i)})(#{h.pack("a"*j)})"
            end
        end
    end
end