Licheng Fang wrote: > Another question: my task is to find in a given string the substrings > that satisfies a particular pattern. That's why the first tool that > came to my mind is regular expression. Parsers, however, only give a > yes/no answer to a given string. To find all substrings with a > particular pattern I may have to try every substring, which may be an > impossible task.
You can collect all successful parser results beginning from each index in the string; this gives you all matches with that first index. You could extend to multiple results general bottom-up context-free language parsing like Earley or Tomita's algorithms; for reasonable languages most locations can be excluded for most rules at the beginning, with great performance improvements over trying over and over again. Lorenzo Gatti -- http://mail.python.org/mailman/listinfo/python-list
