PHP：如何匹配一系列 unicode 配对代理 emoticons/emoji？

Question

anubhava's answer about matching ranges of unicode characters led me to the regex to use for cleaning up a specific range of single code point of characters. With it, now I can match all miscellaneous symbols in this list（包括表情）用这个简单的表达：

preg_replace('/[\x{2600}-\x{26FF}]/u', '', $str);

不过，我也想匹配这个 list of paired/double surrogates emoji, but as nhahtdh explained in a comment:

There is a range from d800 to dfff to specify surrogates in UTF-16 to allow for more characters to be specified. A single surrogate is not a valid character in UTF-16 (a pair is necessary to specify a valid character).

所以，例如，当我尝试这样做时：

preg_replace('/\x{D83D}\x{DE00}/u', '', $str);

用于仅替换第一个 paired surrogates on this list，即：

PHP 抛出这个：

preg_replace(): Compilation failed: disallowed Unicode code point (>= 0xd800 && <= 0xdfff)

我尝试了几种不同的组合，包括 UTF8 for ('/[\x{00F0}\x{009F}\x{0098}\x{0080}]/u'), but I was still unable to match it. I also looked into other PCRE pattern modifiers 中上述代码点的假定组合，但似乎 u 是唯一允许通过 UTF8 指向的组合。

我是否遗漏了任何 "escape" 替代方案？

Answer 1

对找到解决方案很有帮助：

If your PHP isn't shipped with a PCRE build for UTF-16 then you can't perform such a match. From PHP 7.0 on, you're able to use Unicode code points following this syntax \u{XXXX} e.g. preg_replace("~\u{1F600}~", '', $str); (Mind the double quotes)

由于我使用的是PHP 7，echo "\u{1F602}";根据这个PHP RFC page on unicode escape输出。该提案实质上是：

A new escape sequence is added for double-quoted strings and heredocs.

\u{ codepoint-digits } where codepoint-digits is composed of hexadecimal digits.

这意味着 preg_replace 中的匹配字符串（通常是单引号，以免混淆双引号字符串变量扩展），现在需要一些 preg_quote magic。这是我想出的解决方案：

preg_replace(
  // single point unicode list
  "/[\x{2600}-\x{26FF}".
  // http://www.fileformat.info/info/unicode/block/miscellaneous_symbols/list.htm
  // concatenates with paired surrogates
  preg_quote("\u{1F600}", '/')."-".preg_quote("\u{1F64F}", '/').
  // https://www.fileformat.info/info/unicode/block/emoticons/list.htm
  "]/u",
  '',
  $str
);

这是 proof of the above in 3v4l。

编辑：更简单的解决方案

在中，似乎直接将unicode字符放入正则表达式字符class中，支持单引号字符串和以前的PHP版本（例如4.3.4） :

preg_replace('/[☀-⛿-]/u','YOINK',$str);

为了使用PHP 7's new feature though，你还需要双引号：

preg_replace("/[\u{2600}-\u{26FF}\u{1F600}-\u{1F64F}]/u",'YOINK',$str);

这里是revo's proof in 3v4l。

PHP：如何匹配一系列 unicode 配对代理 emoticons/emoji？

PHP: How to match a range of unicode paired surrogates emoticons/emoji?

php

regex

unicode

preg-replace

unicode-escapes

编辑：更简单的解决方案