PHP递归解析嵌套评论的实现方法

[
    ['id' => 1, 'parent_id' => 0, 'content' => '第一条评论'],
    ['id' => 2, 'parent_id' => 1, 'content' => '对第1条的回复'],
    ['id' => 3, 'parent_id' => 2, 'content' => '对第2条的回复'],
    ['id' => 4, 'parent_id' => 0, 'content' => '另一条主评论']
]

function renderComments($comments, $parentId = 0, $level = 0) {
    $html = '';
    
    foreach ($comments as $comment) {
        if ($comment['parent_id'] == $parentId) {
            $padding = str_repeat('   ', $level); // 缩进表示层级
            $html .= "$padding ▶ {$comment['content']}<br>";

            // 递归处理子评论
            $html .= renderComments($comments, $comment['id'], $level + 1);
        }
    }
    
    return $html;
}

echo renderComments($comments);

▶ 第一条评论
   ▶ 对第1条的回复
      ▶ 对第2条的回复
▶ 另一条主评论

function buildCommentTree($comments) {
    $tree = [];
    $map = [];

    // 建立 id => comment 映射
    foreach ($comments as $comment) {
        $map[$comment['id']] = $comment;
        $map[$comment['id']]['children'] = [];
    }

    // 构建父子关系
    foreach ($comments as $comment) {
        if ($comment['parent_id'] == 0) {
            $tree[] = &$map[$comment['id']];
        } else {
            if (isset($map[$comment['parent_id']])) {
                $map[$comment['parent_id']]['children'][] = &$map[$comment['id']];
            }
        }
    }

    return $tree;
}

function renderCommentTree($tree, $level = 0) {
    $html = '';
    foreach ($tree as $comment) {
        $padding = str_repeat('   ', $level);
        $html .= "$padding ▶ {$comment['content']}<br>";
        if (!empty($comment['children'])) {
            $html .= renderCommentTree($comment['children'], $level + 1);
        }
    }
    return $html;
}

$tree = buildCommentTree($comments);
echo renderCommentTree($tree);