正则表达式PCRE 2（PHP〉= 7.3）

我有一个包含多个<img>标签的多行字符串。
使用正则表达式，我想捕获：
a.）包含src属性的整个img标签和
B.）该src属性的内容。

• src属性可以以“”或''结尾，也可以完全不用引号括起来。
• 如果用引号括起来，则属性不应包含“或”
• 如果不加引号，则属性不应包含\s或〉

我花了一整天的时间才使它工作起来，但我需要帮助来改进它。问题是，带引号的src属性在$matches[2]中捕获，而不带引号的src属性转到$matches[3]。由于我需要在一个匹配组中捕获所有路径，所以我将$matches[2]复制到$matches[3]。我宁愿捕获的数据直接转到同一个捕获组。

$code = <<<EOD
1. <img width src = one height>
2. <notAtStart><img src=two height>
3. NotAtAll
4. <img width src="three"><notAtEnd>
5. <notAtStart><img src = 'four' /><notAtEnd>
6. <img src =five><test>
7. <img WithoutSrc>
EOD;

$regex='/(<IMG(?=\s).*\sSRC\s*=\s*
    (?(?=["\'])
        .(.+?) ["\'] 
     |         
        (.+?) [\s>] 
    )
    (?(?<!>).*?>)
)/ix';

preg_match_all($regex, $code, $matches);
echo PHP_EOL . "Matches:";
// print all groups:
print_r($matches);

// copy matches captures in $matches[2] to $matches[3]
foreach($matches[2] as $a=>$b) 
    if ($b != "")
        $matches[3][$a] = $b;

// print the whole captured img tags:
print_r($matches[1]);
// print just the captured paths:
print_r($matches[3]);

输出：

Matches:Array
(
    [0] => Array
        (
            [0] => <img width src = one height>
            [1] => <img src=two height>
            [2] => <img width src="three">
            [3] => <img src = 'four' />
            [4] => <img src =five>
        )

    [1] => Array
        (
            [0] => <img width src = one height>
            [1] => <img src=two height>
            [2] => <img width src="three">
            [3] => <img src = 'four' />
            [4] => <img src =five>
        )

    [2] => Array
        (
            [0] =>
            [1] =>
            [2] => three
            [3] => four
            [4] =>
        )

    [3] => Array
        (
            [0] => one
            [1] => two
            [2] =>
            [3] =>
            [4] => five
        )

)
Array
(
    [0] => <img width src = one height>
    [1] => <img src=two height>
    [2] => <img width src="three">
    [3] => <img src = 'four' />
    [4] => <img src =five>
)
Array
(
    [0] => one
    [1] => two
    [2] => three
    [3] => four
    [4] => five
)

(And是的，我知道，根本不应该使用regex来抓取html，因为不建议这样做。）