DOMXPath::registerPhpFunctions
(PHP 5 >= 5.3.0, PHP 7)
DOMXPath :: registerPhpFunctions - 将PHP函数注册为XPath函数
描述
public void DOMXPath::registerPhpFunctions ([ mixed $restrict ] )这种方法可以在XPath表达式中使用PHP函数。
参数
restrict
使用此参数仅允许从XPath调用某些函数。
该参数可以是一个字符串（一个函数名称）或一组函数名称。
返回值
没有值返回。
例子
以下示例使用book.xml，其中包含以下内容：
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() with php: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";
}
?>上面的例子会输出类似于：
Found 2 books starting with 'PHP':
PHP Basics by Jim Smith
PHP Secrets by Jenny SmytheExample #3 DOMXPath::registerPHPFunctions() with php: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";
}
?>上面的例子会输出类似于：
Books with multiple authors:
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