On Wed, Jun 24, 2009 at 6:13 PM, CuppoJava<patrickli_2...@hotmail.com> wrote:
>
> I need to dynamically create a regex, and would really like to be able
> to use Clojure's built-in regex syntax. But I don't know how to go
> about it.
>
> My regex is: #"(.*?)(\(image .*)"
>
> except instead of "image", I need to dynamically insert an array of
> possible strings to match.
>
> ie. given ["image" "buffer" "spacer"]
>
> I need to produce #"(.*?)(\((?:image|buffer|spacer) .*)"
>
> Is there a nice way of doing this
No, there's really not. I'd love to see a s-expry DSL for
string parsing that was as powerful and nearly as compact as
regex that would be able to do this kind of thing.
...but until then you can convert strings to regex patterns
using re-pattern, and build the strings with the various
tools at hand.
One handy tool is the #"" syntax itself, which works great
for building parts of a larger regex as long as those parts
are legal regex themselves.
Other tools can be found in contrib.
Here the best I've come up with for your example:
(use '[clojure.contrib.str-utils :only [str-join]])
(defn my-regex [words]
(re-pattern (str #"(.*?)" ; stands alone, so #"" works
"(\\((?:" ; regular string, so \ must be escaped
(str-join "|" words)
").*)")))
user=> (my-regex ["image" "buffer" "spacer"])
#"(.*?)(\((?:image|buffer|spacer).*)"
--Chouser
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