Re: why use flex?

Frank Hale (frankhale@worldnet.att.net) pontificated:
> Why would someone use flex as opposed to writing there own lexer? I am
> developing my own scripting language and find it much simpler to
> create a lexer on my own, that way I can tailor it to my needs. What
> makes using flex any easier, the code it generates is very large and
> confusing even for a simple lexer.


I have not found that in my own experience. Flex, to me, is a
no-brainer when it comes to writing lexical scanners. I can usually
whip up a Flex lexer in 1/4 the time it takes me to hand-code one.
The only real complaint I have is the *still* lacking direct C++
support. If one wants that, one has to use to modified Flex++/Bison++
utilities.


> [Writing your first flex lexer takes a while. After that, I find it
> much faster than hand-coding. Also, if you can arrange your lexer so
> it doesn't have to back up, which is usually possible, it's generally
> faster than hand-coded because of the DFA pattern matching engine.
> -John]


It does? I picked up flex faster than I picked up the regex -> FSM
mapping algorithm.
[It does usually take a little while to understand the way flex works,
particularly the fact that yylex() acts like a coroutine that picks up
where it left off if you return. -John]

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