Class FollowedBy

source code

     object --+        
              |        
  ParserElement --+    
                  |    
ParseElementEnhance --+
                      |
                     FollowedBy

Lookahead matching of the given parse expression. FollowedBy does not advance the parsing position within the input string, it only verifies that the specified parse expression matches at the current position. FollowedBy always returns a null token list.

Example:

   # use FollowedBy to match a label only if it is followed by a ':'
   data_word = Word(alphas)
   label = data_word + FollowedBy(':')
   attr_expr = Group(label + Suppress(':') + OneOrMore(data_word, stopOn=label).setParseAction(' '.join))
   
   OneOrMore(attr_expr).parseString("shape: SQUARE color: BLACK posn: upper left").pprint()

prints:

   [['shape', 'SQUARE'], ['color', 'BLACK'], ['posn', 'upper left']]