用PHP中的段落替换双重br和Regex

Question

我有以下文本（来自SQL的字符串）：

Paragraph \n Newline \n\n Paragraph2 \n\n\n\n Paragraph3

此行由以下处理：

function nl2brAndParagraphs($text) {
    $br = nl2br($text);
    $data = preg_replace('/^\s*(?:<br\s*\/?>\s*)*/i', '', $br); //Remove any whitespace and br- tags that are at the beginning of the text
$data = preg_replace('/\s*(?:<br\s*\/?>\s*)*$/i', '', $data); //Remove any whitespace and br- tags that are at the end of the text

$data = preg_replace('#(?:<br\s*/?>\s*?){2,}#','</p>
    <p>',$data); //Replace multiple line breaks with paragraphs
$data = '<p>'.$data.'</p>';
return $data;
}

这应该返回：

<p>Paragraph <br /> Newline </p><p> Paragraph2 </p><p> Paragraph3</p>

但返回

<p>paragraph1 <br /> Newline </p><p> paragraph2 </p><p></p><p> paragraph3</p>

如何修复</p><p></p><p>部分，其中只有</p><p>？

Answer 1

这会将多个连续段落标记合并为一个：

$data = preg_replace('# (\s*<\/p>\s*<p>){2,}#',' <\/p><p>',$data); 

Demo

Answer 2

这会删除所有空段落：

MyCollection.CollectionChanged += System.Specialized.NotifiyCollectionChangedEventHandler(myMethod);