Hi, Every so often the group gets a request for parsing an expression. I think it would be significantly easier to do if regular expressions could modify a stack. However, since you might nearly as well write Python, maybe there is a compromise.
Could the Secret Labs' regular expression engine be modified to operate on lists, for example, or a mutable non-string type? Details (juicy and otherwise): One of the alternatives is to reconstruct a new string on every match, removing the expression and replacing it with a tag. (This by the way takes at least one out-of-band character.) The running time on it involves constructing a string from at least three parts, maybe five: the lead, the opening marker, the inside of the match, the closing marker, and the tail. If it used ropes, it's still constant time, but is O( string length * number of matches ) with just normal strings. Another alternative is to create a new unicode object API, PyUnicode_FROM_DATA, which creates a string object from an existing buffer, but does not copy it. I expect this would receive -1 from many people, not least because it breaks immutability of strings. ctypes character arrays, arrays, and buffer objects are additional possibilities. -- http://mail.python.org/mailman/listinfo/python-list
