Lex numbers

lib/chervil/lexer.rb

       @source[@position]
     end
 
-    def advance
-      @position += 1
+    def advance(step = 1)
+      @position += step
     end
 
     def get_next_token
       case current_char
+      when nil
+        Token.new(:eof, "eof")
       when '('
         advance
         Token.new(:lparen, "(")
       when ')'
         advance
         Token.new(:rparen, ")")
-      when nil
-        Token.new(:eof, "eof")
+      else
+        source = @source.slice(@position..-1)
+        if match = source.match(/^[0-9]+(\.[0-9]+)?/)
+          advance(match[0].size)
+          Token.new(:number, match[0])
+        end
       end
     end
 
       tokens = Array.new
       loop do
         token = get_next_token
+        next if token.nil?
         tokens << token
         break if token.type == :eof
       end

spec/lexer_spec.rb

         ]
       )
     end
+
+    it 'lexes integers' do
+      expect(Lexer.new('1').get_next_token).to eq(Token.new(:number, '1'))
+    end
+
+    it 'lexes floats' do
+      expect(Lexer.new('2.3').get_next_token).to eq(Token.new(:number, '2.3'))
+    end
   end
 end