PHP-REGEX - 在前置标签中用 <br> 替换换行符

Question

我有

<pre>
Line one
Line two
Line three
Line four
Line five
Line six
</pre>

如果我去掉前置标签，它会变成

第一行二号线三号线四号线五号线第六行

用 br 替换新行的正则表达式是什么，以便在剥离 pre 标记后每行都是分开的。

Answer 1

在每个位置你都需要检查你是否在有效的 <pre> 标签内：

~(?s)(?<!<pre>)\R(?!</pre>)(?=((?!<pre>).)*</pre>)~

解释：

(?s)                # Set DOT_ALL modifier
(?<!<pre>)          # Assert if we are not immediately after an opening <pre> tag
\R                  # We need new-lines only
(?!</pre>)          # Not followed by a closing </pre> tag
(?=                 # Beginning of a positive lookahead
    ((?!<pre>).)*   # To look if we are not behind an opening <pre> tag (inside a <pre> tag)
    </pre>          # Which has a closing </pre> tag
)                   # End of lookahead

Live demo

注意：如果您嵌套了 <pre> 标签 (!)[=18，它不会提供预期的结果=]

但是如果您愿意使用 DOM 那么有一个更合适的解决方案：

<?php

$html = <<< HTML
<div>
<div>
test
test
test
</div>
<pre>
Line one
Line two
Line three
Line four
Line five
Line six
</pre>
</div>
HTML;

$dom = new DOMDocument;
@$dom->loadHTML($html, LIBXML_HTML_NOIMPLIED  | LIBXML_HTML_NODEFDTD);
$preTags = $dom->getElementsByTagName('pre');

foreach ($preTags as $key => $pre) {
    $pre->nodeValue = str_replace(PHP_EOL, '~*~*', $pre->nodeValue);
}

echo str_replace("~*~*", '<br />', $dom->saveHTML());

输出：

<div>
<div>
test
test
test
</div>
<pre><br />Line one<br />Line two<br />Line three<br />Line four<br />Line five<br />Line six<br /></pre>
</div>

PHP-REGEX - 在前置标签中用 <br> 替换换行符

PHP-REGEX - Replace line break with <br> within pre tags

php

regex

preg-replace