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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