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  • DOMXPath::registerPhpFunctions()

    (PHP 5 >= 5.3.0, PHP 7)

    Register PHP functions as XPath functions

    说明

    publicDOMXPath::registerPhpFunctions([mixed $restrict]): void

    This method enables the ability to use PHP functions within XPath expressions.

    参数

    $restrict

    Use this parameter to only allow certain functions to be called from XPath.

    This parameter can be either a string(a function name)or an array of function names.

    返回值

    没有返回值。

    范例

    The following examples usebook.xmlwhich contains the following:

    Example #1 book.xml

    <?xml version="1.0" encoding="UTF-8"?>
    <books>
     <book>
      <title>PHP Basics</title>
      <author>Jim Smith</author>
      <author>Jane Smith</author>
     </book>
     <book>
      <title>PHP Secrets</title>
      <author>Jenny Smythe</author>
     </book>
     <book>
      <title>XML basics</title>
      <author>Joe Black</author>
     </book>
    </books>

    Example #2 DOMXPath::registerPHPFunctions() withphp:functionString

    <?php
    $doc = new DOMDocument;
    $doc->load('book.xml');
    $xpath = new DOMXPath($doc);
    // Register the php: namespace (required)
    $xpath->registerNamespace("php", "http://php.net/xpath");
    // Register PHP functions (no restrictions)
    $xpath->registerPHPFunctions();
    // Call substr function on the book title
    $nodes = $xpath->query('//book[php:functionString("substr", title, 0, 3) = "PHP"]');
    echo "Found {$nodes->length} books starting with 'PHP':\n";
    foreach ($nodes as $node) {
        $title  = $node->getElementsByTagName("title")->item(0)->nodeValue;
        $author = $node->getElementsByTagName("author")->item(0)->nodeValue;
        echo "$title by $author\n";
    }
    ?>
    

    以上例程的输出类似于:

    Found 2 books starting with 'PHP':
    PHP Basics by Jim Smith
    PHP Secrets by Jenny Smythe
    

    Example #3 DOMXPath::registerPHPFunctions() withphp:function

    <?php
    $doc = new DOMDocument;
    $doc->load('book.xml');
    $xpath = new DOMXPath($doc);
    // Register the php: namespace (required)
    $xpath->registerNamespace("php", "http://php.net/xpath");
    // Register PHP functions (has_multiple only)
    $xpath->registerPHPFunctions("has_multiple");
     
    function has_multiple($nodes) {
        // Return true if more than one author
        return count($nodes) > 1;
    }
    // Filter books with multiple authors
    $books = $xpath->query('//book[php:function("has_multiple", author)]');
    echo "Books with multiple authors:\n";
    foreach ($books as $book) {
        echo $book->getElementsByTagName("title")->item(0)->nodeValue . "\n";
    }
    ?>
    

    以上例程的输出类似于:

    Books with multiple authors:
    PHP Basics
    

    参见

    • DOMXPath::registerNamespace() Registers the namespace with the DOMXPath object
    • DOMXPath::query() Evaluates the given XPath expression
    • DOMXPath::evaluate() Evaluates the given XPath expression and returns a typed result if possible