Cache common indentation in Inspect.Algebra

lib/elixir/lib/inspect/algebra.ex

@@ -1295,7 +1295,7 @@ defmodule Inspect.Algebra do
     do: format(w, k, t, acc)
 
   defp format(w, _, i, _, doc_line(), t, acc),
-    do: format(w, i, t, <<acc::binary, indent(i)::binary>>)
+    do: format(w, i, t, <<acc::binary, @newline, spaces(i)::binary>>)
 
   defp format(w, k, i, m, doc_cons(x, y), t, acc),
     do: format(w, k, i, m, x, [{i, m, y} | t], acc)
@@ -1325,14 +1325,14 @@ defmodule Inspect.Algebra do
     if w == :infinity or m == :flat or fits?(w, k, true, t) do
       format(w, k, t, <<acc::binary, s::binary>>)
     else
-      format(w, i, t, <<acc::binary, indent(i)::binary>>)
+      format(w, i, t, <<acc::binary, @newline, spaces(i)::binary>>)
     end
   end
 
   # Strict breaks are conditional to the mode
   defp format(w, k, i, mode, doc_break(s, :strict), t, acc) do
     if mode == :break do
-      format(w, i, t, <<acc::binary, indent(i)::binary>>)
+      format(w, i, t, <<acc::binary, @newline, spaces(i)::binary>>)
     else
       format(w, k + byte_size(s), t, <<acc::binary, s::binary>>)
     end
@@ -1388,16 +1388,26 @@ defmodule Inspect.Algebra do
   end
 
   defp collapse(t, max, count, i) do
-    [:binary.copy("\n", min(max, count)), :binary.copy(" ", i) | t]
+    [newlines(min(max, count)), spaces(i) | t]
   end
 
+  defp newlines(0), do: ""
+  defp newlines(1), do: @newline
+  defp newlines(2), do: @newline <> @newline
+  defp newlines(n), do: :binary.copy(@newline, n)
+
   defp strip_whitespace(" " <> rest), do: strip_whitespace(rest)
   defp strip_whitespace(rest), do: rest
 
   defp apply_nesting(_, k, :cursor), do: k
   defp apply_nesting(_, _, :reset), do: 0
   defp apply_nesting(i, _, j), do: i + j
 
-  defp indent(0), do: @newline
-  defp indent(i), do: @newline <> :binary.copy(" ", i)
+  for i <- 0..16 do
+    defp spaces(unquote(i)) do
+      unquote(:binary.copy(" ", i))
+    end
+  end
+
+  defp spaces(i), do: :binary.copy(" ", i)
 end