扩展 PHP 正则表达式以涵盖“srcset”和“style”属性

Question

我创建了一个 WordPress 插件，它根据我在 $tag 和 $attribute 变量中列出的标签和属性将所有链接转换为 protocol-relative URLs（删除 http: 和 https:）。这是功能的一部分。为了节省空间，the rest of the code can be found here。

$content_type = NULL;
# Check for 'Content-Type' headers only
foreach ( headers_list() as $header ) {
    if ( strpos( strtolower( $header ), 'content-type:' ) === 0 ) {
        $pieces = explode( ':', strtolower( $header ) );
        $content_type = trim( $pieces[1] );
        break;
    }
}
# If the content-type is 'NULL' or 'text/html', apply rewrite
if ( is_null( $content_type ) || substr( $content_type, 0, 9 ) === 'text/html' ) {
    $tag = 'a|base|div|form|iframe|img|link|meta|script|svg';
    $attribute = 'action|content|data-project-file|href|src|srcset|style';
    # If 'Protocol Relative URL' option is checked, only apply change to internal links
    if ( $this->option == 1 ) {
        # Remove protocol from home URL
        $website = preg_replace( '/https?:\/\//', '', home_url() );
        # Remove protocol from internal links
        $links = preg_replace( '/(<(' . $tag . ')([^>]*)(' . $attribute . ')=["\'])https?:\/\/' . $website . '/i', '$1//' . $website, $links );
    }
    # Else, remove protocols from all links
    else {
        $links = preg_replace( '/(<(' . $tag . ')([^>]*)(' . $attribute . ')=["\'])https?:\/\//i', '$1//', $links );
    }
}
# Return protocol relative links
return $links;

这按预期工作，但不适用于以下示例：

<!-- Within the 'style' attribute -->
<div class="some-class" style='background-color:rgba(255,255,255,0);background-image:url("http://placehold.it/300x200");background-position:center center;background-repeat:no-repeat'>
<!-- Within the 'srcset' attribute -->
<img src="http://placehold.it/600x300" srcset="http://placehold.it/500 500x, http://placehold.it/100 100w">

但是，代码部分适用于这些示例。

<div class="some-class" style='background-color:rgba(255,255,255,0);background-image:url("http://placehold.it/300x200");background-position:center center;background-repeat:no-repeat'>
<img src="http://placehold.it/600x300" srcset="//placehold.it/500 500x, http://placehold.it/100 100w">

我已经尝试向$tag 和$attribute 变量添加附加值，但这并没有帮助。我假设我需要更新我的正则表达式的其余部分以涵盖这两个额外的标签？还是有其他方法可以解决，比如DOMDocument？

Answer 1

我能够通过执行以下操作来简化代码：

$content_type = NULL;
# Check for 'Content-Type' headers only
foreach ( headers_list() as $header ) {
    if ( strpos( strtolower( $header ), 'content-type:' ) === 0 ) {
        $pieces = explode( ':', strtolower( $header ) );
        $content_type = trim( $pieces[1] );
        break;
    }
}
# If the content-type is 'NULL' or 'text/html', apply rewrite
if ( is_null( $content_type ) || substr( $content_type, 0, 9 ) === 'text/html' ) {
    # Remove protocol from home URL
    $website = $_SERVER['HTTP_HOST'];
    $links = str_replace( 'https?://' . $website, '//' . $website, $links );
    $links = preg_replace( '|https?://(.*?)|', '//$1', $links );
}
# Return protocol relative links
return $links;