Data commit

Task/Brace-expansion/Elixir/brace-expansion.elixir

@@ -0,0 +1,52 @@
+defmodule Brace_expansion do
+  def getitem(s), do: getitem(String.codepoints(s), 0, [""])
+
+  defp getitem([], _, out), do: {out,[]}
+  defp getitem([c|_]=s, depth, out) when depth>0 and (c == "," or c == "}"), do: {out,s}
+  defp getitem([c|t], depth, out) do
+    x = getgroup(t, depth+1, [], false)
+    if (c == "{") and x do
+      {y, z} = x
+      out2 = for a <- out, b <- y, do: a<>b
+      getitem(z, depth, out2)
+    else
+      if c == "\\" and length(t) > 0 do
+        c2 = c <> hd(t)
+        getitem(tl(t), depth, Enum.map(out, fn a -> a <> c2 end))
+      else
+        getitem(t, depth, Enum.map(out, fn a -> a <> c end))
+      end
+    end
+  end
+
+  defp getgroup([], _, _, _), do: nil
+  defp getgroup(s, depth, out, comma) do
+    {g, s2} = getitem(s, depth, [""])
+    if s2 == [] do
+      nil
+    else
+      out2 = out ++ g
+      case hd(s2) do
+        "}" -> if comma, do: {out2, tl(s2)},
+                       else: {Enum.map(out2, &"{#{&1}}"), tl(s2)}
+        "," -> getgroup(tl(s2), depth, out2, true)
+        _   -> getgroup(s2, depth, out2, comma)
+      end
+    end
+  end
+end
+
+test_cases = ~S"""
+~/{Downloads,Pictures}/*.{jpg,gif,png}
+It{{em,alic}iz,erat}e{d,}, please.
+{,{,gotta have{ ,\, again\, }}more }cowbell!
+{}} some }{,{\\{ edge, edge} \,}{ cases, {here} \\\\\}
+""" |> String.split("\n", trim: true)
+
+Enum.each(test_cases, fn s ->
+  IO.puts s
+  Brace_expansion.getitem(s)
+  |> elem(0)
+  |> Enum.each(fn str -> IO.puts "\t#{str}" end)
+  IO.puts ""
+end)