Coroutines could work, though I doubt the complexity (e.g. using yielding iterators with Spirit) or performance will be any better than simply using a FSM-based parser.
Yesterday I tried to switch our server's custom parser to Spirit. Our custom parser is extremely fast and does 0 allocation, but I was ready to take a moderate performance hit to gain in readability and maintainability. The problem we have is that if we want to add more features to our custom commands - note, this is not a web server, this is something much more simpler - it will make the code more complex whereas in Spirit it will just be a matter of adding new rules without adding any new dependencies (we already use boost, so the library is in our build and release chain). In addition, I love the way Spirit tackles the problem. Unfortunately, I forgot I spent a certain amount of time optimizing our custom parser to be a zero-copy, zero-allocation parser (not to mention a fair deal of mpl to have basically very little code at runtime). Basically, the current parser spits out a pair of read-only pointers for each block you want to work on when with Spirit the straightforward way implies creating a string, which means in many case making a dreaded memory allocation (yes, I have a problem with this :p). Maybe MSM is more suited for that kind of tasks. I also want to mention that I'm a noob when it comes to Spirit so perhaps with more magic one could achieve results closer to our custom parser. When our version one is released, I will work more on that custom parser vs MSM vs Spirit thingy and let you know. Generally speaking I think it is worth spending some time with Spirit because writing a grammar to parse input is an order of magnitude easier to maintain than writing a custom parser. I'd also want to point out that MSM will soon land in Boost and it is a viable alternative for this kind of problems. -Edouard __________ Information from ESET NOD32 Antivirus, version of virus signature database 4826 (20100202) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com