正则表达式中的括号内的字边界不起作用 [英] Word boundary does not work inside brackets in regex
问题描述
我注意到在 PHP 中执行 preg_replace() 时，单词边界 \bword\b 在括号内不起作用.
I have noticed that the word boundary \bword\b does not work inside brackets when doing a preg_replace() in PHP.
具体来说，我试图排除完整的词 >(在 HTML 中代表 >)，但由于词边界不会触发在 [^\b>\b] 中的括号内，任何这些字符本身，如 g 或 &，将被检测为不匹配.如果您尝试在括号外进行匹配，\b 在 PHP 中按预期工作，即使单词以 & 开头，但不是字符.
Specifically, I'm trying to exclude the full word > (which stands for > in HTML), but since the word boundary does not trigger inside brackets as in [^\b>\b], any of those characters by itself, like g or &, will be detected as a non-match. If you try to do a match outside the brackets, \b works as expected in PHP even though the word starts with a & a non-character.
有任何想法/想法可以解决这种情况吗?
Any thoughts/ideas to get around this situation?
推荐答案
在PHP中排除，(*SKIP)(*F)是你的朋友
在 PHP 中，由于强大的 (*SKIP)(*F) 语法(在 Perl 中也可用)，排除任何东西都非常简单.
In PHP, excluding anything is frighteningly simple thanks to the powerful (*SKIP)(*F) syntax (also available in Perl).
要排除 > 并观看其他内容，您可以这样做:
To exclude > and watch something else, you can just do this:
>(*SKIP)(*F)|something_else
交替的左侧 | 匹配完整的 > 然后故意失败，之后引擎跳到字符串中的下一个位置.右边匹配something_else，我们知道它不是>，因为它没有被左边的表达式匹配.只需确保 something_else 不是诸如 .* 之类的通用内容，因为它可能会覆盖所有以下 > 实例.例如，在这里，\w+ 将是 something_else 的完美模式，因为它与 >
The left side of the alternation | matches complete >then deliberately fails, after which the engine skips to the next position in the string. The right side matches something_else, and we know that it is not > because it was not matched by the expression on the left. Just make sure that something_else is not something generic such as .* as that could roll over all the following > instances. For instance, here, \w+ would be a perfectly fine pattern for something_else, as it does not clash with >
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