Added Oga::EntityDecoder

This module removes some of the code duplication needed to determine
what entity decoder to use.

lib/oga.rb

@@ -6,6 +6,7 @@ require 'thread'
 require_relative 'oga/version'
 require_relative 'oga/oga'
 require_relative 'oga/lru'
+require_relative 'oga/entity_decoder'
 
 # Load these first so that the native extensions don't have to define the
 # Oga::XML namespace.

lib/oga/entity_decoder.rb

@@ -0,0 +1,21 @@
+module Oga
+  module EntityDecoder
+    ##
+    # @see [decode]
+    #
+    def self.try_decode(input, html = false)
+      return input ? decode(input, html) : nil
+    end
+
+    ##
+    # @param [String] input
+    # @param [TrueClass|FalseClass] html
+    # @return [String]
+    #
+    def self.decode(input, html = false)
+      decoder = html ? HTML::Entities : XML::Entities
+
+      return decoder.decode(input)
+    end
+  end # EntityDecoder
+end # Oga

lib/oga/xml/text.rb

@@ -27,8 +27,7 @@ module Oga
       #
       def text
         unless @decoded
-          decoder  = html? ? HTML::Entities : Entities
-          @text    = decoder.decode(@text)
+          @text    = EntityDecoder.try_decode(@text, html?)
           @decoded = true
         end