Make prune part of the public API in the formatter

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Author: José Valim

lib/logger/lib/logger/backends/console.ex

@@ -82,7 +82,7 @@ defmodule Logger.Backends.Console do
       IO.write(device, output)
     rescue
       ArgumentError ->
-        IO.write(device, Logger.Utils.prune(output))
+        IO.write(device, Logger.Formatter.prune(output))
     end
   end
 

lib/logger/lib/logger/formatter.ex

@@ -44,6 +44,26 @@ defmodule Logger.Formatter do
   @type pattern :: :date | :level | :levelpad | :message | :metadata | :node | :time
   @valid_patterns [:time, :date, :message, :level, :node, :metadata, :levelpad]
   @default_pattern "\n$time $metadata[$level] $levelpad$message\n"
+  @replacement "�"
+
+  @doc """
+  Prune non-valid UTF-8 codepoints.
+
+  Typically called after formatting when the data cannot be printed.
+  """
+  @spec prune(IO.chardata) :: IO.chardata
+  def prune(binary) when is_binary(binary), do: prune_binary(binary, "")
+  def prune([h|t]) when h in 0..1114111, do: [h|prune(t)]
+  def prune([h|t]), do: [prune(h)|prune(t)]
+  def prune([]), do: []
+  def prune(_), do: @replacement
+
+  defp prune_binary(<<h::utf8, t::binary>>, acc),
+    do: prune_binary(t, <<acc::binary, h::utf8>>)
+  defp prune_binary(<<_, t::binary>>, acc),
+    do: prune_binary(t, <<acc::binary, @replacement>>)
+  defp prune_binary(<<>>, acc),
+    do: acc
 
   @doc ~S"""
   Compiles a format string into an array that the `format/5` can handle.

lib/logger/lib/logger/utils.ex

@@ -1,25 +1,6 @@
 defmodule Logger.Utils do
   @moduledoc false
 
-  @replacement "�"
-
-  @doc """
-  Prune non-valid UTF-8 codepoints.
-  """
-  @spec prune(IO.chardata) :: IO.chardata
-  def prune(binary) when is_binary(binary), do: prune_binary(binary, "")
-  def prune([h|t]) when h in 0..1114111, do: [h|prune(t)]
-  def prune([h|t]), do: [prune(h)|prune(t)]
-  def prune([]), do: []
-  def prune(_), do: @replacement
-
-  defp prune_binary(<<h::utf8, t::binary>>, acc),
-    do: prune_binary(t, <<acc::binary, h::utf8>>)
-  defp prune_binary(<<_, t::binary>>, acc),
-    do: prune_binary(t, <<acc::binary, @replacement>>)
-  defp prune_binary(<<>>, acc),
-    do: acc
-
   @doc """
   Truncates a char data into n bytes.
 

lib/logger/test/logger/formatter_test.exs

@@ -4,6 +4,14 @@ defmodule Logger.FormatterTest do
 
   import Logger.Formatter
 
+  test "prune/1" do
+    assert prune(1) == "�"
+    assert prune(<<"hí", 233>>) == "hí�"
+    assert prune(["hi"|233]) == ["hi"|"�"]
+    assert prune([233|"hi"]) == [233|"hi"]
+    assert prune([[]|[]]) == [[]]
+  end
+
   defmodule CompileMod do
     def format(_level, _msg, _ts, _md) do
       true

lib/logger/test/logger/utils_test.exs

@@ -6,14 +6,6 @@ defmodule Logger.UtilsTest do
   import Kernel, except: [inspect: 2]
   defp inspect(format, args), do: Logger.Utils.inspect(format, args, 10)
 
-  test "prune/1" do
-    assert prune(1) == "�"
-    assert prune(<<"hí", 233>>) == "hí�"
-    assert prune(["hi"|233]) == ["hi"|"�"]
-    assert prune([233|"hi"]) == [233|"hi"]
-    assert prune([[]|[]]) == [[]]
-  end
-
   test "truncate/2" do
     # ASCII binaries
     assert truncate("foo", 4) == "foo"