Upstream sync

Rakefile

@@ -44,3 +44,16 @@ Rake::RDocTask.new do |rdoc|
   rdoc.rdoc_files.include('README*')
   rdoc.rdoc_files.include('lib/**/*.rb')
 end
+
+desc 'Generate Lexer'
+task :lexer do
+  `rex ./lib/specification.rex -o ./lib/lexer.rb`
+end
+
+desc 'Generate Parser'
+task :parser do
+  `racc ./lib/grammar.y -o ./lib/parser.rb`
+end
+
+desc 'Generate Lexer and Parser'
+task generate: %i[lexer parser]