"Eric S. Raymond" <esr@thyrsus.com>:
Tim Peters <tim.one@comcast.net>:
But you lost me here -- I don't see a connection between immutability and either ease of writing lexers or speed of lexers. It's an implementation problem. You find yourself doing a lot of string accessing and pasting, creating several new objects per input char.
Not necessarily! Plex manages to do it without any of that. The trick is to leave all the characters in the input buffer and just *count* how many characters make up the next token. Once you've decided where the token ends, one slice gives it to you. Greg Ewing, Computer Science Dept, +--------------------------------------+ University of Canterbury, | A citizen of NewZealandCorp, a | Christchurch, New Zealand | wholly-owned subsidiary of USA Inc. | greg@cosc.canterbury.ac.nz +--------------------------------------+