写一个二叉树php代码，function

下面是一个简单的二叉树 PHP 代码，包括二叉树的节点结构和基本操作函数：

class Node {
    public $value;
    public $left;
    public $right;

    function __construct($val) {
        $this->value = $val;
        $this->left = null;
        $this->right = null;
    }
}

class BinaryTree {
    public $root;

    function __construct() {
        $this->root = null;
    }

    function insert($val) {
        $newNode = new Node($val);

        if ($this->root === null) {
            $this->root = $newNode;
        } else {
            $current = $this->root;
            
            while (true) {
                if ($val < $current->value) {
                    if ($current->left === null) {
                        $current->left = $newNode;
                        break;
                    } else {
                        $current = $current->left;
                    }
                } else {
                    if ($current->right === null) {
                        $current->right = $newNode;
                        break;
                    } else {
                        $current = $current->right;
                    }
                }
            }
        }
    }

    function search($val) {
        $current = $this->root;

        while ($current !== null) {
            if ($val === $current->value) {
                return true;
            } elseif ($val < $current->value) {
                $current = $current->left;
            } else {
                $current = $current->right;
            }
        }

        return false;
    }

    function inorderTraversal($node, &$result) {
        if ($node === null) {
            return;
        }

        $this->inorderTraversal($node->left, $result);
        $result[] = $node->value;
        $this->inorderTraversal($node->right, $result);
    }

    function preorderTraversal($node, &$result) {
        if ($node === null) {
            return;
        }

        $result[] = $node->value;
        $this->preorderTraversal($node->left, $result);
        $this->preorderTraversal($node->right, $result);
    }

    function postorderTraversal($node, &$result) {
        if ($node === null) {
            return;
        }

        $this->postorderTraversal($node->left, $result);
        $this->postorderTraversal($node->right, $result);
        $result[] = $node->value;
    }
}

这个代码包含了二叉树的基本操作，包括插入节点、查找节点、中序、前序、后序遍历等。