在有根有向无环树中获取父门的后代作为子对象（节点和门）的一维数组

Question

我的有根有向无环树将由逻辑门（与、或、异或...）和节点.

a node & a gate,每一个都是object.

只有一个门可以是父门。

每个 gate 对象都有 children 属性作为 public. children 可以是 对象数组 或 空数组 .

下面是我的案例的有效树。 (g:门, n:node)

g1
|---|---|---|---|
n1  n2  n3  g2  g3
            |\
           n4 n5

我的目标

以对象数组的形式获取门的后代。（例如：print_r($gate1->getDescendants())）

我的问题

这是我的第一次oop体验，我尝试做一个与我的工作相关的小应用程序。在我下面的代码中，我知道有问题的部分是：$this->descendants[] = $obj;

如果我将此行更改为 $descendants，则由于变量范围问题，输出仍然不正确。

如何让 $gate1->getDescendants() 正常工作？

预期输出正确

下方树的 7 个子对象的一维数组。 (g:门, n:node)

g1
|---|---|---|---|
n1  n2  n3  g2  g3
            |\
           n4 n5

我得到的输出不正确

Array
(
    [0] => Node Object
        (
            [id] => 1
        )

    [1] => Node Object
        (
            [id] => 2
        )

    [2] => Node Object
        (
            [id] => 3
        )

    [3] => Gate Object
        (
            [id] => 2
            [type] => or
            [desc] => My First OR Gate
            [children] => Array
                (
                    [0] => Node Object
                        (
                            [id] => 4
                        )

                    [1] => Node Object
                        (
                            [id] => 5
                        )

                )

            [descendants] => Array
                (
                    [0] => Node Object
                        (
                            [id] => 4
                        )

                    [1] => Node Object
                        (
                            [id] => 5
                        )

                )

        )

    [4] => Gate Object
        (
            [id] => 3
            [type] => xor
            [desc] => My First XOR Gate
            [children] => Array
                (
                )

            [descendants] => 
        )

)

代码：class节点，class门，try.php

class Node
{
    public $id;

    public function __construct($id)
    {
        $this->id = $id;
    }
}

class门

class Gate
{
    public $id;
    public $type;
    public $desc;
    public $children = array();
    public $descendants;

    public function __construct($id, $type, $desc)
    {
        $this->id = $id;
        $this->type = $type;
        $this->desc = $desc;            
    }

    public function addChild($child)
    {
        if($child instanceof Node OR $child instanceof Gate)
        {
            $this->children[] = $child;
        }
        else
        {               
            throw new Exception('Child of Gate must be a Node or Gate object!');
        }
    }

    public function getDescendants()
    {           
        if(!empty($this->children))
        {
            $count_children = count($this->children);

            for ($i = 0; $i < $count_children; $i++) 
            {
                $obj = $this->children[$i];

                $this->descendants[] = $obj;
                // i tried also below
                // $descendants[] = $obj;

                if($obj instanceof Gate)
                {                           
                    $obj->getDescendants();                         
                }
            }

            return $this->descendants;
            // i tried also below
            //return $descendants;
        }
        else
        {
            return $this->children;
        }
    }
}

try.php

require_once('Node.php');
require_once('Gate.php');

$node1 = new Node(1);   
$node2 = new Node(2);   
$node3 = new Node(3);
$node4 = new Node(4);   
$node5 = new Node(5);   

$gate1 = new Gate(1,'and','My First AND Gate'); 
$gate2 = new Gate(2,'or','My First OR Gate');
$gate3 = new Gate(3,'xor','My First XOR Gate');

$gate1->addChild($node1);
$gate1->addChild($node2);
$gate1->addChild($node3);
$gate1->addChild($gate2);
$gate1->addChild($gate3);

$gate2->addChild($node4);
$gate2->addChild($node5);

function pa($var)
{
    echo '<pre>';print_r($var);echo '</pre>';
}

/**
 * get top gate's descandants
 * (not only 1st level,
 * but children @all levels)
 */
pa($gate1->getDescendants());

Answer 1

一个小调整：

if($obj instanceof Gate)
{
    $this->descendants = array_merge($this->descendants, $obj->getDescendants());
}

当您调用 $obj->getDescendants() 时，您并未使用返回值。

我假设您希望它合并到 descendants 变量中，因为您正在请求 7 元素数组响应。

在有根有向无环树中获取父门的后代作为子对象（节点和门）的一维数组

Get descendants of a parent gate as a 1-dim array of child objects (nodes & gates) in a rooted directed acyclic tree

php

oop

object

tree

descendant