正则表达式用于过滤不以单词结尾的字符串

Question

I am trying to write a regex for filtering out perforce changelist descriptions which are not pending.

So string " Change 358618 on 2013/11/09 by abcdm@abcd_PQRST_UVWXY " should pass but string " Change 358618 on 2013/11/09 by abcdm@abcd_PQRST_UVWXY *pending* " should not. So far i have come up with the following.

($token1,$token2,$token3) = ( $string =~ /^Change\s+([0-9]+)\s+(.*)\s(?!\\*pending\\*)/ );

So if the pattern matches i should be able to consume the changelist number. If the changelist is pending, no tokens will be returned.

Answer 1

在表达式的末尾使用否定的后置断言：

(?<!\*pending\*)$

Answer 2

I would not solve this problem using Regex as it is an expensive operation. If you are certain that the strings that you wish to exclude ends with pending just check that part of the string using offsets:

$string1 = 'Change 358618 on 2013/11/09 by abcdm@abcd_PQRST_UVWXY *pending*';
$string2 = '*pending*';

$offset = length($string1) - length($string2);

$result = index($string1, $string2, $offset);