setup files for parser part

Rakefile

@@ -2,11 +2,19 @@ require 'rspec/core/rake_task'
 
 RSpec::Core::RakeTask.new do |c|
   options = ['--color']
-  options += ["--format", "documentation"]
+  options += %w[--format documentation]
   c.rspec_opts = options
 end
 
-desc "Generate Lexer"
+desc 'Generate Lexer'
 task :lexer do
   `rex specification.rex -o lexer.rb`
-end
+end
+
+desc 'Generate Parser'
+task :parser do
+  `racc grammar.y -o parser.rb`
+end
+
+desc 'Generate Lexer and Parser'
+task generate: %i[lexer parser]