36 lines
991 B
Elixir
36 lines
991 B
Elixir
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defmodule TopSecret do
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def to_ast(string), do: Code.string_to_quoted!(string)
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def decode_secret_message_part({is_function?, _, arguments} = ast, acc)
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when is_function? in [:defp, :def] do
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{ast, [get_letters(arguments) | acc]}
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end
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def decode_secret_message_part(ast, acc), do: {ast, acc}
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defp get_letters([{:when, _, arguments} | _]), do: get_letters(arguments)
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defp get_letters([{name, _, arguments} | _]) when is_list(arguments),
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do: letters_from_name_and_arguments(name, arguments)
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defp get_letters([{name, _, arguments} | _]) when is_atom(arguments),
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do: letters_from_name_and_arguments(name, [])
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defp letters_from_name_and_arguments(name, arguments) do
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name
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|> Atom.to_string()
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|> String.slice(0, length(arguments))
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end
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def decode_secret_message(string) do
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{_ast, result} =
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string
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|> to_ast()
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|> Macro.prewalk([], &decode_secret_message_part/2)
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result
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|> Enum.reverse()
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|> Enum.join()
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end
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end
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