Ignore whitespace

lib/chervil/lexer.rb

       when ')'
         advance
         Token.new(:rparen, ")")
+      when ' '
+        advance
+        nil
       else
         source = @source.slice(@position..-1)
         if match = source.match(/^[0-9]+(\.[0-9]+)?/)

spec/lexer_spec.rb

     it 'lexes floats' do
       expect(Lexer.new('2.3').get_next_token).to eq(Token.new(:number, '2.3'))
     end
+
+    it 'ignores whitespace' do
+      expect(Lexer.new('1 2 3').tokenize).to eq(
+        [
+          Token.new(:number, '1'),
+          Token.new(:number, '2'),
+          Token.new(:number, '3'),
+          Token.new(:eof, 'eof')
+        ]
+      )
+    end
   end
 end