Load Rouge files using methods scoped to the Rouge module (rouge-ruby…

…#1481)

Rouge currently uses two global methods defined in `lib/rouge.rb`,
`#load_relative` and `#lexer_dir`, to load the various files in the
Rouge library. Rather than add methods to the global namespace, it
would be preferable if the loading methods were within the Rouge module.

This commits adds two methods to Rouge's singleton class, `#load_file`
and `#load_lexers`, and updates `lib/rouge.rb` to use these methods.

lib/rouge.rb

@@ -35,63 +35,73 @@ def highlight(text, lexer, formatter, &b)
 
       formatter.format(lexer.lex(text), &b)
     end
-  end
-end
 
-# mimic Kernel#require_relative API
-def load_relative(path)
-  load File.join(Rouge::LIB_DIR, "#{path}.rb")
-end
+    # Load a file relative to the `lib/rouge` path.
+    #
+    # @api private
+    def load_file(path)
+      load File.join(LIB_DIR, "rouge/#{path}.rb")
+    end
 
-def lexer_dir(path = '')
-  File.join(Rouge::LIB_DIR, 'rouge/lexers', path)
+    # Load the lexers in the `lib/rouge/lexers` directory.
+    #
+    # @api private
+    def load_lexers
+      # The trailing slash is necessary to avoid lexers being loaded multiple
+      # times by `Lexers.load_lexer`
+      lexer_dir = File.join(LIB_DIR, "rouge/lexers/")
+      Dir.glob(File.join(lexer_dir, '*.rb')).each do |f|
+        Lexers.load_lexer(f.sub(lexer_dir, ''))
+      end
+    end
+  end
 end
 
-load_relative 'rouge/version'
-load_relative 'rouge/util'
-load_relative 'rouge/text_analyzer'
-load_relative 'rouge/token'
+Rouge.load_file 'version'
+Rouge.load_file 'util'
+Rouge.load_file 'text_analyzer'
+Rouge.load_file 'token'
 
-load_relative 'rouge/lexer'
-load_relative 'rouge/regex_lexer'
-load_relative 'rouge/template_lexer'
+Rouge.load_file 'lexer'
+Rouge.load_file 'regex_lexer'
+Rouge.load_file 'template_lexer'
 
-Dir.glob(lexer_dir('*rb')).each { |f| Rouge::Lexers.load_lexer(f.sub(lexer_dir, '')) }
+Rouge.load_lexers
 
-load_relative 'rouge/guesser'
-load_relative 'rouge/guessers/util'
-load_relative 'rouge/guessers/glob_mapping'
-load_relative 'rouge/guessers/modeline'
-load_relative 'rouge/guessers/filename'
-load_relative 'rouge/guessers/mimetype'
-load_relative 'rouge/guessers/source'
-load_relative 'rouge/guessers/disambiguation'
+Rouge.load_file 'guesser'
+Rouge.load_file 'guessers/util'
+Rouge.load_file 'guessers/glob_mapping'
+Rouge.load_file 'guessers/modeline'
+Rouge.load_file 'guessers/filename'
+Rouge.load_file 'guessers/mimetype'
+Rouge.load_file 'guessers/source'
+Rouge.load_file 'guessers/disambiguation'
 
-load_relative 'rouge/formatter'
-load_relative 'rouge/formatters/html'
-load_relative 'rouge/formatters/html_table'
-load_relative 'rouge/formatters/html_pygments'
-load_relative 'rouge/formatters/html_legacy'
-load_relative 'rouge/formatters/html_linewise'
-load_relative 'rouge/formatters/html_line_table'
-load_relative 'rouge/formatters/html_inline'
-load_relative 'rouge/formatters/terminal256'
-load_relative 'rouge/formatters/terminal_truecolor'
-load_relative 'rouge/formatters/tex'
-load_relative 'rouge/formatters/null'
+Rouge.load_file 'formatter'
+Rouge.load_file 'formatters/html'
+Rouge.load_file 'formatters/html_table'
+Rouge.load_file 'formatters/html_pygments'
+Rouge.load_file 'formatters/html_legacy'
+Rouge.load_file 'formatters/html_linewise'
+Rouge.load_file 'formatters/html_line_table'
+Rouge.load_file 'formatters/html_inline'
+Rouge.load_file 'formatters/terminal256'
+Rouge.load_file 'formatters/terminal_truecolor'
+Rouge.load_file 'formatters/tex'
+Rouge.load_file 'formatters/null'
 
-load_relative 'rouge/theme'
-load_relative 'rouge/tex_theme_renderer'
-load_relative 'rouge/themes/thankful_eyes'
-load_relative 'rouge/themes/colorful'
-load_relative 'rouge/themes/base16'
-load_relative 'rouge/themes/github'
-load_relative 'rouge/themes/igor_pro'
-load_relative 'rouge/themes/monokai'
-load_relative 'rouge/themes/molokai'
-load_relative 'rouge/themes/monokai_sublime'
-load_relative 'rouge/themes/gruvbox'
-load_relative 'rouge/themes/tulip'
-load_relative 'rouge/themes/pastie'
-load_relative 'rouge/themes/bw'
-load_relative 'rouge/themes/magritte'
+Rouge.load_file 'theme'
+Rouge.load_file 'tex_theme_renderer'
+Rouge.load_file 'themes/thankful_eyes'
+Rouge.load_file 'themes/colorful'
+Rouge.load_file 'themes/base16'
+Rouge.load_file 'themes/github'
+Rouge.load_file 'themes/igor_pro'
+Rouge.load_file 'themes/monokai'
+Rouge.load_file 'themes/molokai'
+Rouge.load_file 'themes/monokai_sublime'
+Rouge.load_file 'themes/gruvbox'
+Rouge.load_file 'themes/tulip'
+Rouge.load_file 'themes/pastie'
+Rouge.load_file 'themes/bw'
+Rouge.load_file 'themes/magritte'