PHP多维数组中特定子元素的首位管理策略

$arr = array(
    "svg" => array(
        0 => array("@style" => "overflow:visible", "@xlink:href" => "test.png"),
        1 => array("g" => "", "@id" => "Layer_2"),
        2 => array("g" => "", "@id" => "Layer_3"),
        3 => array("title" => "test") // 这里的'title'元素可能在任何位置，也可能不存在
    ),
    "@version" => 1.2,
    "@baseProfile" => "tiny-ps",
    "@id" => "Layer_1",
    "@xmlns" => "http://www.w3.org/2000/svg"
);

<?php

/**
 * 确保多维数组中特定子数组的'title'元素位于首位。
 * 如果'title'元素不存在，则添加一个默认值；如果存在，则将其移动到首位。
 *
 * @param array $arr 待处理的多维数组，通过引用传递。
 */
function manageSvgTitlePosition(&$arr)
{
    // 检查'svg'键是否存在且为数组
    if (!isset($arr['svg']) || !is_array($arr['svg'])) {
        // 如果'svg'键不存在或不是数组，则直接添加一个包含默认标题的'svg'数组
        $arr['svg'] = [['title' => 'test']];
        return;
    }

    $new_svg = [];
    $titleFound = false; // 标记是否在原始数组中找到了title元素
    $actualTitleValue = 'test'; // 默认标题值

    // 遍历原始的'svg'数组，构建新的数组
    foreach ($arr['svg'] as $item) {
        // 检查当前元素是否包含'title'键
        if (array_key_exists('title', $item)) {
            $actualTitleValue = $item['title']; // 获取实际的标题值
            $titleFound = true; // 标记已找到title
        } else {
            // 如果不是title元素，则添加到新数组中
            $new_svg[] = $item;
        }
    }

    // 将实际的或默认的title元素添加到新数组的最前面
    array_unshift($new_svg, ['title' => $actualTitleValue]);

    // 将构建好的新数组替换原始的'svg'子数组
    $arr['svg'] = $new_svg;
}

?>

<?php
$arr1 = [
    "svg" => [
        ["@style" => "overflow:visible", "@xlink:href" => "test.png"],
        ["g" => "", "@id" => "Layer_2"],
        ["g" => "", "@id" => "Layer_3"],
        ["title" => "Fred"] // 'title'元素在末尾
    ],
    "@version" => 1.2,
    "@baseProfile" => "tiny-ps",
    "@id" => "Layer_1",
    "@xmlns" => "http://www.w3.org/2000/svg"
];

echo "--- 原始数组 (title存在) ---\n";
print_r($arr1);

manageSvgTitlePosition($arr1);

echo "\n--- 处理后的数组 (title存在) ---\n";
print_r($arr1);
/*
预期输出:
Array
(
    [svg] => Array
        (
            [0] => Array
                (
                    [title] => Fred
                )
            [1] => Array
                (
                    [@style] => overflow:visible
                    [@xlink:href] => test.png
                )
            [2] => Array
                (
                    [g] =>
                    [@id] => Layer_2
                )
            [3] => Array
                (
                    [g] =>
                    [@id] => Layer_3
                )
        )
    [@version] => 1.2
    [@baseProfile] => tiny-ps
    [@id] => Layer_1
    [@xmlns] => http://www.w3.org/2000/svg
)
*/
?>

<?php
$arr2 = [
    "svg" => [
        ["@style" => "overflow:visible", "@xlink:href" => "test.png"],
        ["g" => "", "@id" => "Layer_2"],
        ["g" => "", "@id" => "Layer_3"]
    ],
    "@version" => 1.2,
    "@baseProfile" => "tiny-ps",
    "@id" => "Layer_1",
    "@xmlns" => "http://www.w3.org/2000/svg"
];

echo "--- 原始数组 (title不存在) ---\n";
print_r($arr2);

manageSvgTitlePosition($arr2);

echo "\n--- 处理后的数组 (title不存在) ---\n";
print_r($arr2);
/*
预期输出:
Array
(
    [svg] => Array
        (
            [0] => Array
                (
                    [title] => test
                )
            [1] => Array
                (
                    [@style] => overflow:visible
                    [@xlink:href] => test.png
                )
            [2] => Array
                (
                    [g] =>
                    [@id] => Layer_2
                )
            [3] => Array
                (
                    [g] =>
                    [@id] => Layer_3
                )
        )
    [@version] => 1.2
    [@baseProfile] => tiny-ps
    [@id] => Layer_1
    [@xmlns] => http://www.w3.org/2000/svg
)
*/
?>