regex - 如何使用 preg_replace 在第三段和第四段之间插入文本字符串？

Question

我正在尝试弄清楚如何在 WordPress 帖子中创建一个名为“pullquote”的常见报纸设备。 (但这并不是严格意义上的 WordPress 问题；它更像是一个通用的正则表达式问题。)我有一个标签来包围帖子中的文本。我想复制标签之间的文本(我知道该怎么做)并将其插入帖子中 p 标签的第三个和第四个实例之间。

下面的函数查找文本并删除标签，但只是将匹配的文本添加到开头。我需要帮助定位第三/第四段

或者...也许我的想法是错误的。也许有某种方法可以像使用 jQuery nth-child 那样定位元素？

帖子:

<p>If you wanna improve yer German, don't try to read Heine or some elevated crap... watch old episodes of [callout]Tatort or Bukow & Konig[/callout].</p>
<p>If I were teaching a music appreciation I wouldn't teach Beethoven. I'd teach Stamitz and average composers.</p>
<p>And here is a 3rd paragraph.</p>
<p>And here is a 4th paragraph.</p>

期望的结果

<p>If you wanna improve yer German, don't try to read Heine or some elevated crap... watch old episodes of Tatort or Bukow & Konig.</p>
<p>If I were teaching a music appreciation I wouldn't teach Beethoven. I'd teach Stamitz and average composers.</p>
<p>And here is a 3rd paragraph.</p>
<blockquote class="pullquote">Tatort or Bukow & Konig</blockquote>
<p>And here is a 4th paragraph.</p>

到目前为止，这就是我的代码:

function jchwebdev_pullquote( $content ) {
    $newcontent = $content;
    $replacement = '$1';
    $matches = array();
    $pattern = "~\[callout\](.*?)\[/callout\]~s";
    // strip out 'shortcode'
    $newcontent = preg_replace($pattern, $replacement, $content);
    if( preg_match($pattern, $content, $matches)) {
      // now have formatted pullquote 
      $pullquote = '<blockquote class="pullquote">' .$matches[1] . '</blockquote>';
      // now how do I target and insert $pullquote
      // between 3rd and 4th paragraph?
      preg_replace($3rd_4th_pattern, $3rd_4th_replacement,
      $newcontent);
      return $newcontent;
    }
    return $content;    
}
add_filter( 'the_content' , 'jchwebdev_pullquote');

编辑:我想修改我的问题，使其更具体一点。 WordPress 实际上将换行符转换为

字符。大多数 WordPress 帖子甚至不使用明确的“p”标签，因为它们是不需要的。到目前为止，解决方案的问题在于它们似乎删除了换行符，因此如果帖子(源文本)有换行符，它看起来很奇怪。

典型的现实世界 WordPress 帖子:

If you wanna improve yer German, don't try to read Heine or some elevated crap... watch old episodes of [callout]Tatort or Bukow & Konig[/callout].

If I were teaching a music appreciation I wouldn't teach Beethoven. I'd teach Stamitz and average composers.

And here is a 3rd paragraph.


And here is a 5th paragraph.

Wordpress 的渲染方式如下:

<p>If you wanna improve yer German, don't try to read Heine or some elevated crap... watch old episodes of [callout]Tatort or Bukow & Konig[/callout].</p>
<p>If I were teaching a music appreciation I wouldn't teach Beethoven. I'd teach Stamitz and average composers.</p>
<p>And here is a 3rd paragraph.</p>
<p></p>
<p>And here is a 5th paragraph.</p>

因此，在完美的世界中，我想采用“典型的现实世界帖子”并让 preg_replace 将其渲染为:

If you wanna improve yer German, don't try to read Heine or some elevated crap... watch old episodes of Tatort or Bukow & Konig.

If I were teaching a music appreciation I wouldn't teach Beethoven. I'd teach Stamitz and average composers.

And here is a 3rd paragraph.

<blockquote class="callout">Tatort or Bukow & Konig</blockquote>

And here is a 5th paragraph.

...Wordpress 将呈现为:

<p>If you wanna improve yer German, don't try to read Heine or some elevated crap... watch old episodes of Tatort or Bukow & Konig.</p>
<p>If I were teaching a music appreciation I wouldn't teach Beethoven. I'd teach Stamitz and average composers.</p>
<p>And here is a 3rd paragraph.</p>
<blockquote class="callout">Tatort or Bukow & Konig</blockquote>
<p>And here is a 5th paragraph.</p>

也许这已经离谱太远了，我应该在 WordPress 论坛中重新发布，但我认为我需要的是一种改变 preg_replace 的方法，以使用换行符作为分隔符而不是

并弄清楚如何从返回的字符串中删除那些换行符。

感谢迄今为止提供的所有帮助!

Answer 1

如果想使用PHP HTML/XML解析，请引用How do you parse and process HTML/XML in PHP? .

对于正则表达式解决方案，这里是一个正则表达式解决方案:

查找: (?s)((?:<p>.*?<\/p>\s*){3})

这个正则表达式只会捕获前 3 个 <p>标签，然后在它们后面添加一个节点。

替换: $1<blockquote class="pullquote">Tatort or Bukow & Konig</blockquote>\n

代码:

$re = "/(?s)((?:<p>.*?<\\/p>\\s*){3})/"; 
$str = "<p>If you wanna improve yer German, don't try to read Heine or some elevated crap... watch old episodes of [callout]Tatort or Bukow & Konig[/callout].</p>\n<p>If I were teaching a music appreciation I wouldn't teach Beethoven. I'd teach Stamitz and average composers.</p>\n<p>And here is a 3rd paragraph.</p>\n<p>And here is a 4th paragraph.</p>"; 
$subst = "$1<blockquote class=\"pullquote\">Tatort or Bukow & Konig</blockquote>\n"; 
$result = preg_replace($re, $subst, $str, 1);

Demo is here .