Data commit

Task/Align-columns/Elixir/align-columns.elixir

@@ -0,0 +1,35 @@
+defmodule Align do
+  def columns(text, alignment) do
+    fieldsbyrow = String.split(text, "\n", trim: true)
+                  |> Enum.map(fn row -> String.split(row, "$", trim: true) end)
+    maxfields = Enum.map(fieldsbyrow, fn field -> length(field) end) |> Enum.max
+    colwidths = Enum.map(fieldsbyrow, fn field -> field ++ List.duplicate("", maxfields - length(field)) end)
+                |> List.zip
+                |> Enum.map(fn column ->
+                     Tuple.to_list(column) |> Enum.map(fn col-> String.length(col) end) |> Enum.max
+                   end)
+    Enum.each(fieldsbyrow, fn row ->
+      Enum.zip(row, colwidths)
+      |> Enum.map(fn {field, width} -> adjust(field, width, alignment) end)
+      |> Enum.join(" ") |> IO.puts
+    end)
+  end
+
+  defp adjust(field, width, :Left),  do: String.pad_trailing(field, width)
+  defp adjust(field, width, :Right), do: String.pad_leading(field, width)
+  defp adjust(field, width, _),      do: :string.centre(String.to_charlist(field), width)
+end
+
+text = """
+Given$a$text$file$of$many$lines,$where$fields$within$a$line$
+are$delineated$by$a$single$'dollar'$character,$write$a$program
+that$aligns$each$column$of$fields$by$ensuring$that$words$in$each$
+column$are$separated$by$at$least$one$space.
+Further,$allow$for$each$word$in$a$column$to$be$either$left$
+justified,$right$justified,$or$center$justified$within$its$column.
+"""
+
+Enum.each([:Left, :Right, :Center], fn alignment ->
+  IO.puts "\n# #{alignment} Column-aligned output:"
+  Align.columns(text, alignment)
+end)