[erlang-questions] improving the performance of regexp(regular expressions)
Fri Jul 4 04:33:06 CEST 2008
Others are probably going to say this as well, but my experience with
Erlang is that it isn't great for regex. It's great for a lot of
other things, but not regex (yet!).
Pre-R12B-3, I had a lot of success using pattern matches in situations
where my initial reaction was to use regex. While it was a bit more
code, it was a lot easier to comprehend than regex code and, through
using a layer of fun() calls, it ran blazingly fast. For the specific
project, I had to do a lot of (pattern matching|regex) *and* have it
run as quickly as possible; from a coding perspective, what I lost in
having to put together a bunch of pattern matches (in place of what
would have been a single regex in e.g. Perl), I got back many times
over in terms of performance in the finished product.
Now that R12B-3 is here, I'll probably look at the re changes, but
I've now got some experience that tells me that regex isn't the be-all
and end-all of data parsing solutions. If you've got the chance, you
might find it's worth looking at what you can do with pattern matching
in place of regex.
2008/7/1 Jesper Louis Andersen <>:
> 2008/7/1 chamila piyasena <>:
>> Hi all,
>> Is there a new implementation of regexp.erl or can anyone suggest a way to
>> improve the performance of the functionalities given in the regexp.erl
>> without using regexp library written in C.
> Seriously: Consider something else than regular expressions if it is
> possible. Some languages, most notably perl has used regular
> expressions extensively and thus has a pretty fast implementation of
> them. But usually you can easily write code without them. Maybe you
> can read the data in a more structured format, maybe you can
> pre-process the data into a simpler format or maybe you can skip parts
> of the data.
> Rather than trying to brute-force yourself through the mouse-hole, use
> the door in the wall ;)
> Regular expressions have their uses, but they indeed also have their abuses.
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