Re: NSPredicate regex
Re: NSPredicate regex
- Subject: Re: NSPredicate regex
- From: "Stephen J. Butler" <email@hidden>
- Date: Fri, 19 Feb 2010 01:17:25 -0600
On Tue, Feb 16, 2010 at 9:55 AM, martin halter <email@hidden> wrote:
> NSString *regex = @"(?:.*[\\s\\W0-9])*cache(?:[\\s\\W0-9].*)*";
Your regex is pathological. It's not hard to confuse the matcher with
really convoluted regular expressions. Consider this: how is your
pattern any different from...
NSString *regex = @"cache";
Since your atoms before and after "cache" can match 0 or more times,
you could greatly simplify the thing by just not matching at all!
Never mind the .* inside the atoms.
If you want to match the word cache that is surrounded by some sort of
defined separators, I'd suggest:
(^|[\s\W0-9])cache([\s\W0-9]|$)
Broken down:
- the start of the string, or some other selected separator
- cache
- some other selected separator, or the end of the string
That should match cache in this instances:
"cache"
"cache some other stuff"
"some other stuff cache"
"some other cache stuff"
"cache/some other stuff"
"some other stuff/cache"
"some other/cache/stuff"
"cache0some other stuff"
"some other stuff0cache"
"some other1cache2stuff"
But not: "some othercachestuff"
Note: I'm not familiar with the particular flavor of regexes ICU uses.
More used to Java and PCRE. But this is the basic idea.
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