Fix regression in LazyHTML.Tree.to_html/1 memory usage (#19)

Author: jonatanklosko

lib/lazy_html.ex

@@ -498,7 +498,7 @@ defmodule LazyHTML do
   """
   @spec html_escape(String.t()) :: String.t()
   def html_escape(string) when is_binary(string) do
-    LazyHTML.Tree.append_escaped(string, "")
+    LazyHTML.Tree.html_escape(string)
   end
 
   # Access

lib/lazy_html/tree.ex

@@ -133,8 +133,12 @@ defmodule LazyHTML.Tree do
   #
   # [1]: https://github.com/phoenixframework/phoenix_html/blob/v4.2.1/lib/phoenix_html/engine.ex#L29-L35
 
-  @doc false
-  def append_escaped(text, html) do
+  # Note: it is important for this function to be private, so that the
+  # Erlang compiler can infer that it is safe to use mutating appends
+  # on the underlying binary and maximise optimisations [1].
+  #
+  # [1]: https://github.com/dashbitco/lazy_html/pull/19
+  defp append_escaped(text, html) do
     append_escaped(text, text, 0, 0, html)
   end
 
@@ -275,4 +279,7 @@ defmodule LazyHTML.Tree do
 
     tree
   end
+
+  @doc false
+  def html_escape(string), do: append_escaped(string, "")
 end