ID1019-Programming-II/morse.ex at master · Agriad/ID1019-Programming-II · GitHub

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defmodule Morse do

    def test() do
        signal = '... --- ... '
        decode(signal)
    end

    def decode(signal) do
        table = decode_table()
        decode(signal, table, table)
    end

    ## Fill in the empty ... spaces
    def decode([], _, _) do  []  end
    def decode([?- | rest], {:node, char, long, short}, table) do
        decode(rest, long, table)
    end
    def decode([?. | rest], {:node, char, long, short}, table) do
        decode(rest, short, table)
    end
    def decode([?\s | rest], {:node, char, long, short}, table) do
        [char | decode(rest, table, table)]
    end


    # Some test samples to decode, a signal must end with a space ' '
    def base(), do: '.- .-.. .-.. ..-- -.-- --- ..- .-. ..-- -... .- ... . ..-- .- .-. . ..-- -... . .-.. --- -. --. ..-- - --- ..-- ..- ... '

    def rolled(), do: '.... - - .--. ... ---... .----- .----- .-- .-- .-- .-.-.- -.-- --- ..- - ..- -... . .-.-.- -.-. --- -- .----- .-- .- - -.-. .... ..--.. ...- .----. -.. .--.-- ..... .---- .-- ....- .-- ----. .--.-- ..... --... --. .--.-- ..... ---.. -.-. .--.-- ..... .---- '

    # Morse decoding tree as {:node, char, long, short}
    defp decode_table do
        {:node, :na,
        {:node, 116,
            {:node, 109,
            {:node, 111,
                {:node, :na, {:node, 48, nil, nil}, {:node, 57, nil, nil}},
                {:node, :na, nil, {:node, 56, nil, {:node, 58, nil, nil}}}},
            {:node, 103,
                {:node, 113, nil, nil},
                {:node, 122,
                {:node, :na, {:node, 44, nil, nil}, nil},
                {:node, 55, nil, nil}}}},
            {:node, 110,
            {:node, 107, {:node, 121, nil, nil}, {:node, 99, nil, nil}},
            {:node, 100,
                {:node, 120, nil, nil},
                {:node, 98, nil, {:node, 54, {:node, 45, nil, nil}, nil}}}}},
        {:node, 101,
            {:node, 97,
            {:node, 119,
                {:node, 106,
                {:node, 49, {:node, 47, nil, nil}, {:node, 61, nil, nil}},
                nil},
                {:node, 112,
                {:node, :na, {:node, 37, nil, nil}, {:node, 64, nil, nil}},
                nil}},
            {:node, 114,
                {:node, :na, nil, {:node, :na, {:node, 46, nil, nil}, nil}},
                {:node, 108, nil, nil}}},
            {:node, 105,
            {:node, 117,
                {:node, 32,
                {:node, 50, nil, nil},
                {:node, :na, nil, {:node, 63, nil, nil}}},
                {:node, 102, nil, nil}},
            {:node, 115,
                {:node, 118, {:node, 51, nil, nil}, nil},
                {:node, 104, {:node, 52, nil, nil}, {:node, 53, nil, nil}}}}}}
    end

end