如何将>分隔的多级分类字符串转换为无限层级嵌套关联数组

推荐方案：引用传址实现（无递归、性能更高） #

该方案无需递归，时间复杂度仅为O(n)，无层级上限，是生产环境最优选择：

function buildNestedCategories(string $pathStr, string $delimiter = '>'): array
{
    // 分割路径、去除分类名前后空格、过滤空分类
    $categoryList = array_filter(array_map('trim', explode($delimiter, $pathStr)));
    $nestedArray = [];
    // 引用指针跟踪当前操作的嵌套层级
    $currentLevel = &$nestedArray;

    foreach ($categoryList as $categoryName) {
        // 若当前层级不存在该分类则初始化空数组
        if (!isset($currentLevel[$categoryName])) {
            $currentLevel[$categoryName] = [];
        }
        // 指针下移到当前分类的子层级
        $currentLevel = &$currentLevel[$categoryName];
    }

    return $nestedArray;
}

使用示例 #

$categoryPath = "Category 1 > SubCategory 2 > SubSubCategory 3 > SubSubSubCategory 4";
$result = buildNestedCategories($categoryPath);

// 验证结构
var_dump(isset($result['Category 1']['SubCategory 2']['SubSubCategory 3']['SubSubSubCategory 4'])); // 输出 bool(true)

可选方案：递归实现 #

如果更习惯递归写法可以用该方案，注意PHP默认递归深度限制为100层，超深层级场景不推荐：

function buildNestedCategoriesRecursive(array $categoryList, int $currentIndex = 0): array
{
    if ($currentIndex >= count($categoryList)) {
        return [];
    }
    return [
        $categoryList[$currentIndex] => buildNestedCategoriesRecursive($categoryList, $currentIndex + 1)
    ];
}

使用示例 #

$categoryPath = "Category 1 > SubCategory 2 > SubSubCategory 3";
$categoryList = array_filter(array_map('trim', explode('>', $categoryPath)));
$result = buildNestedCategoriesRecursive($categoryList);

内容的提问来源于stack exchange，提问作者Adrian Emil Tudorache