PHP | DOMXPath registerPhpFunctions()函数

DOMXPath::registerPhpFunctions()函数是PHP中的一个内置函数，用于启用在 XPath 表达式中使用PHP函数的能力。

句法：

void DOMXPath::registerPhpFunctions( mixed $restrict )

参数：此函数接受一个可选的单个参数$restrict ，其中包含要限制的函数。

返回值：此函数不返回任何值。

下面给出的程序说明了PHP中的DOMXPath::registerPhpFunctions()函数：

方案一：

    
        
        Mr. A
        Mr. B
    
    
        
        Mr. C
    

XML;
  
// Load the XML
$document->loadXML($xml);
  
// Create a new DOMXPath instance
$xpath = new DOMXPath($document);
  
// Register the php: namespace
$xpath->registerNamespace("php",
        "http://php.net/xpath");
  
// Register PHP functions
$xpath->registerPHPFunctions();
  
// Use the PHP function to find
// the books starting with FOO
$query = '//book[php:functionString('
        . '"substr", title, 0, 3) = "FOO"]';
  
// Execute the query
$entries = $xpath->evaluate($query);
  
echo "Found $entries->length books"
        . " starting with 'FOO':\n";
foreach ($entries as $node) {
    $title = $node->getElementsByTagName(
                "title")->item(0)->nodeValue;
    echo "
$title";
}
?>

输出：

Found 2 books starting with 'FOO':
FOO BAR
FOO BAZ

方案二：

    
        
        Mr. A
        Mr. B
    
    
        
        Mr. C
    

XML;
   
// Load the XML
$document->loadXML($xml);
   
// Create a new DOMXPath instance
$xpath = new DOMXPath($document);
   
// Register the php: namespace
$xpath->registerNamespace("php",
        "http://php.net/xpath");
   
// Register PHP functions
$xpath->registerPHPFunctions();
   
// Use the manually created 
// PHP function in query
$query = '//book[php:function('
        . '"has_multiple", author)]';
   
// Execute the query
$entries = $xpath->evaluate($query);
   
echo "Found $entries->length books "
        . "with multiple authors:\n";
  
foreach ($entries as $node) {
    $title = $node->getElementsByTagName(
            "title")->item(0)->nodeValue;
    echo "
$title";
}
   
function has_multiple($nodes) {
      
    // Return true if more than
    // one author is there
    return count($nodes) > 1;
}
?>

输出：

Found 1 books with multiple authors:
FOO BAR

参考： https://www. PHP.net/manual/en/domxpath.registerphpfunctions。 PHP