Lex identifiers

lib/chervil/lexer.rb

         if match = source.match(/^[0-9]+(\.[0-9]+)?/)
           advance(match[0].size)
           Token.new(:number, match[0])
+        elsif match = source.match(/^[a-z!$%&*\/:<=>?~_^][a-z0-9@!$%&*\/:<=>?~_^,+\-]*/)
+          advance(match[0].size)
+          Token.new(:identifier, match[0])
         end
       end
     end

spec/lexer_spec.rb

         ]
       )
     end
+
+    it 'lexes identifiers' do
+      expect(Lexer.new('hello').get_next_token).to eq(
+        Token.new(:identifier, 'hello')
+      )
+    end
   end
 end