Question

我想解析一些HTML，根据该文档中的标题创建嵌套导航。

像这样的数组就是我想要创造的：

[
  'name' => 'section 1',
  'number' => '1',
  'level' => 1,
  'children' => [
    [
      'name' => 'sub section 1',
      'number' => '1.1',
      'level' => 2,
      'children' => []
    ],
    [
      'name' => 'sub section 2',
      'number' => '1.2',
      'level' => 2,
      'children' => []
    ]
  ],
]

因此，如果文档在H2之后有一个H3，则代码可以解析它并为每个连续的H标题层创建一个带子元素的嵌套数组

我想它需要做一些主要的事情：

获取所有标题
递归循环（H2后的H3应该是数组中的子节点）
创建部分编号1.1.1或1.1.2，例如

这是我提取标题的代码：

$dom = new \DomDocument();
$dom->loadHTML($html, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);

// Extract the heading structure
$xpath = new \DomXPath($dom);
$headings = $xpath->query('//h1|//h2|//h3|//h4|//h5|//h6');

我试图创建一个递归函数，但我不确定最佳方法让它工作

Answer 1

测试非常困难，因为这取决于HTML的复杂程度和您使用的特定页面。此外，由于代码做了很多，我会让你知道它做了什么，因为解释会持续一段时间。 XPath是使用XPath select all elements between two specific elements作为参考来创建的，用于选择两个标记之间的数据。测试源（test.html）仅仅是......

<html>
<head>
</head>
<body>
    <h2>Header 1</h2>
    <h2>Header 2</h2>
    <h3>Header 2.1</h3>
    <h4>Header 2.1.1</h4>
    <h2>Header 3</h2>
    <h3>Header 3.1</h3>
</body>
</html>

实际代码是......

function extractH ( $level, $xpath, $dom, $position = 0, $number = ''  )  {
    $output = [];
    $prevLevel = $level-1;
    $headings = $xpath->query("//*/h{$level}[count(preceding-sibling::h{$prevLevel})={$position}]");
    foreach ( $headings as $key => $heading )   {
        $sectionNumber = ltrim($number.".".($key+1), ".");
        $newOutput = ["name" => $heading->nodeValue,
            "number" => $sectionNumber,
            "level" => $level
            ];
        $children = extractH($level+1, $xpath, $dom, $key+1, $sectionNumber);
        if ( !empty($children) )    {
            $newOutput["children"] = $children;
        }
        $output[] =$newOutput;
    }

    return $output;
}

$html = file_get_contents("test.html");
$dom = new \DomDocument();
$dom->loadHTML($html, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
$xpath = new \DomXPath($dom);
$output = extractH(2, $xpath, $dom);
print_r($output);

对extractH()的调用参数很少。由于示例HTML仅以h2标签（无h1）开头，因此第一个参数为2.然后使用XPath和DomDocument对象。

Answer 2

可接受的答案不适用于以下结构：

<h2>a</h2>
    <h3>aa</h3>
        <h4>aaa</h4>
            <h5>aaaa</h5>
                <h6>aaaaa</h6>
<h2>b</h2>
<h2>c</h2>
    <h3>ca</h3>
    <h3>cb</h3>
    <h3>cc</h3>
<h2>d</h2>
    <h3>da</h3>
        <h4>daa</h4>
            <h5>daaa</h5>
                <h6>daaaa</h6>

“ d”部分中的树被替换为“ a”部分中的树

此解决方案对我有用

class Parser {
    private $counter = [
        1 => 0,
        2 => 0,
        3 => 0,
        4 => 0,
        5 => 0,
        6 => 0,
    ];

    public function generate(string $text) {
        $dom = new DOMDocument('1.0', 'utf-8');
        $dom->loadHTML(mb_convert_encoding($text, 'HTML-ENTITIES', 'UTF-8'), LIBXML_HTML_NOIMPLIED);
        $xpath = new DOMXPath($dom);
        $tree = $this->extractHeadings(2, $xpath, $dom);

        return $tree;
    }


    private function extractHeadings($level, DOMXPath $xpath, DOMDocument $dom, $position = 0)  {
        $result = [];
        $prevLevel = $level-1;

        $query = "//*/h{$level}[count(preceding::h{$prevLevel})={$position}]";
        $headings = $xpath->query($query);

        foreach ($headings as $key => $heading) {
            $this->counter[$level]++;
            $item = [
                'value' => $heading->nodeValue,
                'level' => $level,
                'children' => [],
            ];
            $children = $this->extractHeadings($level+1, $xpath, $dom, $this->counter[$level]);
            if (!empty($children))    {
                $item['children'] = $children;
            }
            $result[] = $item;
        }

        return $result;
    }


}

$text = "
    <h2>a</h2>
        <h3>aa</h3>
            <h4>aaa</h4>
                <h5>aaaa</h5>
                    <h6>aaaaa</h6>
    <h2>b</h2>
    <h2>c</h2>
        <h3>ca</h3>
        <h3>cb</h3>
        <h3>cc</h3> 
    <h2>d</h2>
        <h3>da</h3>
            <h4>daa</h4>
                 <h5>daaa</h5>
                     <h6>daaaa</h6>
";

$parser = new Parser();
$parser->generate($text);

但仍然希望标题有序

PHP从DOM创建头标记的递归列表

2 个答案: