php - preg_replace 仅外部标签？ (...我们不是在谈论完整的 'html parsing' ，只是一些 Markdown )

Question

突出显示某些文本(不包括 OCCASIONAL 标签“<...>”中的文本)的最简单方法是什么？

澄清:我希望保留现有标签!

$t = 
preg_replace(
  "/(markdown)/",
  "<strong>$1</strong>",
"This is essentially plain text apart from a few html tags generated with some
simplified markdown rules: <a href=markdown.html>[see here]</a>");

应该显示为:

“这基本上是纯文本，除了一些使用一些简化的 ma​​rkdown 规则生成的 html 标签:see here”

...但不要弄乱 anchor 标记内的文本(即 <a href=markdown.html>)。

我听说过不使用正则表达式解析 html 的争论，但这里我们主要讨论的是纯文本，除了对一些 markdown 代码进行最少的解析。

Answer 1

实际上，这似乎工作正常:

<?php
$item="markdown";
$t="This is essentially plain text apart from a few html tags generated 
with some simplified markdown rules: <a href=markdown.html>[see here]</a>";

//_____1. apply emphasis_____
$t = preg_replace("|($item)|","<strong>$1</strong>",$t);

// "This is essentially plain text apart from a few html tags generated 
// with some simplified <strong>markdown</strong> rules: <a href=
// <strong>markdown</strong>.html>[see here]</a>"

//_____2. remove emphasis if WITHIN opening and closing tag____
$t = preg_replace("|(<[^>]+?)(<strong>($item)</strong>)([^<]+?>)|","$1$3$4",$t);

// this preserves the text before ($1), after ($4) 
// and inside <strong>..</strong> ($2), but without the tags ($3)

// "This is essentially plain text apart from a few html tags generated
// with some simplified <strong>markdown</strong> rules: <a href=markdown.html>
// [see here]</a>"

?>

像 $item="odd|string" 这样的字符串会导致一些问题，但无论如何我不会使用那种字符串...(可能需要 htmlentities(...)等等……)