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elixir-koans/lib/blanks.ex
2016-04-23 21:39:22 +01:00

40 lines
1.1 KiB
Elixir

defmodule Blanks do
def replace(ast, replacement) when not is_list(replacement), do: replace(ast, [replacement])
def replace([do: ast], replacements), do: [do: replace(ast, replacements)]
def replace(ast, replacements) do
ast
|> Macro.prewalk(replacements, &pre/2)
|> elem(0)
end
defp pre(:___, [first | remainder]), do: {first, remainder}
defp pre({:___, _, _}, [first | remainder]), do: {first, remainder}
defp pre(node, acc), do: {node, acc}
def count(ast) do
ast
|> Macro.prewalk(0, &count/2)
|> elem(1)
end
defp count(:___, acc), do: {node, acc+1}
defp count({:___, _, _}, acc), do: {node, acc+1}
defp count(node, acc), do: {node, acc}
def replace_line([do: ast], replacement_fn), do: [do: replace_line(ast, replacement_fn)]
def replace_line({:__block__, meta, lines}, replacement_fn) do
replaced_lines = Enum.map(lines, fn(line) ->
replace_line(line, replacement_fn)
end)
{:__block__, meta, replaced_lines}
end
def replace_line(line, replacement_fn) do
if Blanks.count(line) > 0 do
replacement_fn.(line)
else
line
end
end
end