PHP无法将包含PHP代码的文件作为文本文件读取

$filename = 'yourfile.php';
$filecontent = highlight_file($filename, true);
echo $filecontent;

$filename = 'yourfile.php';
$filecontent = file_get_contents($filename);
$filecontent_escaped = htmlspecialchars($filecontent);
echo $filecontent_escaped;

$filename = 'yourfile.php';
$filecontent = file_get_contents($filename);
$tokens = token_get_all($filecontent);
foreach ($tokens as $token) {
    if (is_array($token)) {
        echo $token[1];
    } else {
        echo $token;
    }
}