Change log level from "info" to "debug" (#488)

Closes #481

README.md

@@ -262,6 +262,14 @@ There are also some selectors based on non-standard specifications. They are:
 | E:fl-contains('foo')  | an E element that contains "foo" inside a text node                    |
 | E:fl-icontains('foo') | an E element that contains "foo" inside a text node (case insensitive) |
 
+## Suppressing log messages
+
+Floki may log debug messages related to problems in the parsing of selectors, or parsing of the HTML tree.
+It also may log some "info" messages related to deprecated APIs. If you want to suppress these log messages,
+please consider setting the `:compile_time_purge_matching` option for `:logger` in your compile time configuration.
+
+See https://hexdocs.pm/logger/Logger.html#module-compile-configuration for details.
+
 ## Special thanks
 
 * [@arasatasaygin](https://github.com/arasatasaygin) for Floki's logo from the [Open Logos project](http://openlogos.org/).

lib/floki/finder.ex

@@ -1,6 +1,4 @@
 defmodule Floki.Finder do
-  require Logger
-
   @moduledoc false
 
   # The finder engine traverse the HTML tree searching for nodes matching

lib/floki/selector.ex

@@ -229,7 +229,7 @@ defmodule Floki.Selector do
   end
 
   defp pseudo_class_match?(_html_node, %{name: unknown_pseudo_class}, _tree) do
-    Logger.info(fn ->
+    Logger.debug(fn ->
       "Pseudo-class #{inspect(unknown_pseudo_class)} is not implemented. Ignoring."
     end)
 

lib/floki/selector/parser.ex

@@ -143,7 +143,7 @@ defmodule Floki.Selector.Parser do
   end
 
   defp do_parse([{:unknown, _, unknown} | t], selector) do
-    Logger.info(fn -> "Unknown token #{inspect(unknown)}. Ignoring." end)
+    Logger.debug(fn -> "Unknown token #{inspect(unknown)}. Ignoring." end)
 
     do_parse(t, selector)
   end
@@ -179,7 +179,7 @@ defmodule Floki.Selector.Parser do
   end
 
   defp consume_attribute(:consuming, [unknown | t], attr_selector) do
-    Logger.info(fn -> "Unknown token #{inspect(unknown)}. Ignoring." end)
+    Logger.debug(fn -> "Unknown token #{inspect(unknown)}. Ignoring." end)
     consume_attribute(:consuming, t, attr_selector)
   end
 
@@ -264,7 +264,7 @@ defmodule Floki.Selector.Parser do
   end
 
   defp update_pseudo_not_value(_pseudo_class, _pseudo_not_selector) do
-    Logger.info("Only simple selectors are allowed in :not() pseudo-class. Ignoring.")
+    Logger.debug("Only simple selectors are allowed in :not() pseudo-class. Ignoring.")
     nil
   end
 end

lib/floki/selector/pseudo_class.ex

@@ -102,7 +102,7 @@ defmodule Floki.Selector.PseudoClass do
         relative_position in s
 
       expression ->
-        Logger.info(fn ->
+        Logger.debug(fn ->
           "Pseudo-class #{name} with expressions like #{inspect(expression)} are not supported yet. Ignoring."
         end)