PHP：通过递归迭代构建邻接表

Question

我正在尝试构建一个扁平化数组，以保留来自我的 CodeIgniter 项目中一个视图的非常棘手的数组的元数据。该元数据类似于标识符、深度和父节点。

数据来自查询生成器 JavaScript 库，该库允许用户生成将在业务逻辑中使用的规则。我需要保留这些数据，而我用来表示这些规则的树状性质的模型是一个邻接列表。

这是我的，它适用于大多数情况，但它很丑，它是用泡泡糖和胶带制成的，'most' 个案例不是 'all' 个案例。阅读 SPL 文档后，我怀疑 RecursiveIteratorIterator 可能更适合这个问题。

抱歉啰嗦 post，但我很确定我的方法很糟糕。有什么建议吗？

这是输入（例如，我不想去的地方），示例图片也展示了它的实际效果：

这是持久性所需的输出。（有关元数据的重要部分，请参阅每个条目最右侧的值）。

Array
(
    stdClass Object ( [id] => Any [field] => Any [type] => string [input] => select [operator] => not equal [value] => Any [condition] => OR [subgroup] => 0 [parent_subgroup] => )
    stdClass Object ( [id] => Place [field] => Place [type] => string [input] => select [operator] => equal [value] => France) [condition] => AND [subgroup] => 1 [parent_subgroup] => 0 )
    stdClass Object ( [id] => Month [field] => Month [type] => string [input] => select [operator] => equal [value] => January [condition] => AND [subgroup] => 1 [parent_subgroup] => 0 )
    stdClass Object ( [id] => Place [field] => Place [type] => string [input] => select [operator] => equal [value] => Rio [condition] => AND [subgroup] => 2 [parent_subgroup] => 0 )
    stdClass Object ( [id] => Month [field] => Month [type] => string [input] => select [operator] => equal [value] => August[condition] => AND [subgroup] => 2 [parent_subgroup] => 0 )
    stdClass Object ( [id] => Place [field] => Place [type] => string [input] => select [operator] => equal [value] => Liberia [condition] => AND [subgroup] => 3 [parent_subgroup] => 0 )
    stdClass Object ( [id] => Month [field] => Month [type] => string [input] => select [operator] => equal [value] =>  July[condition] => AND [subgroup] => 3 [parent_subgroup] => 0 )
    stdClass Object ( [id] => Year [field] => Year [type] => string [input] => select [operator] => equal [value] => 2014 [condition] => OR [subgroup] => 4 [parent_subgroup] => 3 )
    stdClass Object ( [id] => Year [field] => Year [type] => string [input] => select [operator] => equal [value] => 2015 [condition] => OR [subgroup] => 4 [parent_subgroup] => 3 )    
)

注意：解析正确。如果我更改了子组 2 和 3 的顺序，就会出现问题，因为组 3 的子组具有规则（Year = 2014 OR Year = 2015）具有不同的嵌套级别并严重扰乱了我的递归。

这是我的代码：

function deserialize_criteria_group($criteria, $subgroup = null) {
    $array = array();

    if ($subgroup == null) {
        $first_run = true;
        $subgroup = 0;
        $condition = $criteria->condition;
        $criteria = $criteria->rules;
    }

    foreach ($criteria as $rule) {
        if ($rule->rules) {
            $subgroup++;
            $children = $this->deserialize_criteria_group($rule->rules, $subgroup);
            foreach($children as $child) {
                if ($child->condition == null) {
                    $child->condition = $rule->condition;
                }
                if ($child->parent_subgroup == null) {
                    $child->parent_subgroup = $first_run ? 0 : $subgroup - 1;
                }
                    array_push($array, $child);
            }
        } else {
            $rule->condition = $condition;
            $rule->subgroup = $subgroup;
            $rule->parent_subgroup = null;
            array_push($array, $rule);
        }

    }

    if ($first_run) {
        //Ensure a root node exists, if not stub one out. 
        $criteria_group = json_decode(json_encode($array), true);
        $root_encountered = $criteria_group[0]['subgroup'] > 0 ? false : true;
        if (!$root_encountered) {
            $root = array(  'subgroup'          => 0, 
                            'parent_subgroup'   => null, 
                            'condition'         => $condition);
            array_unshift($criteria_group, $root); 
            array_unshift($array, $root);
        }

        //Ensure the ALM is not broken. 
        $subgroup = 0;
        foreach($criteria_group as $c) {
            if($c['subgroup'] > $subgroup + 1) {
                $msg = "Bad Order. Halting execution.";
                print $msg; 
                log_message('error', $msg); 
                log_message('debug', 'expected: ' . $subgroup . ' actual: ' . $c['subgroup']);
                log_message('debug', print_r($criteria_group, true));
                die;
            }
            $subgroup = $c['subgroup'];
        }
    }
    return $array;
}

Answer 1

感谢 Rocket Hazmat 的协助。

编辑：看来我错过了一些代码，抱歉。

EDIT2：这种方法还产生了一些其他问题。我在下面显示更正。

解决方案：

<?php
class CriteriaIterator implements RecursiveIterator{
    private $data, $counter, $condition, $subgroup, $parent_subgroup;

    public function __construct($criteriaGroup, $condition, $parent_subgroup=null){
            $this->condition = $condition;
            $this->subgroup = $GLOBALS['highest_subgroup'];
            $this->parent_subgroup = $parent_subgroup;
            $this->data = is_array($criteriaGroup) ? $criteriaGroup : array($criteriaGroup);
    }

    public function current(){
            $row = $this->data[$this->counter];
            if ($row->id) {
                    return (object) array(
                            'id' => $row->id,
                            'field' => $row->id,
                            'operator' => $row->operator,
                            'value' => $row->value,
                            'condition'=> $this->condition,
                            'subgroup' => $GLOBALS['highest_subgroup'],
                            'parent_subgroup' => $this->parent_subgroup
                    );
            }
    }

    public function key(){
            return $this->counter;
    }

    public function next(){
            $this->counter++;
    }

    public function rewind(){
            $this->counter = 0;
    }

    public function valid(){
        return $this->counter < count($this->data);
    }

    public function hasChildren(){
        $row = $this->data[$this->counter];
        return isset($row->rules);
    }

    public function getChildren(){    
        $GLOBALS['highest_subgroup']++;
        $row = $this->data[$this->counter];
        return new self($row->rules, $row->condition, $this->subgroup);
    }
}

之后像这样调用和清理：（最后有点懒，改装成 CodeIgniter 运行 PHP 5.3）

$records = new RecursiveIteratorIterator(
    new CriteriaIterator($a['criteria_group'], $a['criteria_group']->condition),
    RecursiveIteratorIterator::SELF_FIRST);

$criteria = array();
$parent_encountered = false;

// cleanup
foreach($records as $row) {
    if($row != null) {
        $row->parent_subgroup = $row->parent_subgroup == - 1 ? null : $row->parent_subgroup;
        if($row->parent_subgroup === null) {
            $parent_encountered = true;
        }
        array_push($criteria, $row);
    }
}

if(!$parent_encountered) {
    $row = array(
        'subgroup' => 0,
        'parent_subgroup' => null,
        'condition' => $a['criteria_group']->condition
    );
    array_unshift($criteria, json_decode(json_encode($row)));
}

问题出现在子组成员上。我的检索方法使用广度优先搜索来创建要传递到脚本中的 json 对象。不幸的是，在重新保存时，嵌套级别的事情变得一发不可收拾。

这是一个会导致混淆的设置示例。值之前的天数显示预期的子组。

可能可以在递归迭代器 class 中修复，但 Rocket Hazmat 建议让 class 非常简单。我在清理期间实施了修复：

        $records = new RecursiveIteratorIterator(
                new CriteriaIterator($a['criteria_group'], $a['criteria_group']->condition), 
                RecursiveIteratorIterator::SELF_FIRST);

        $criteria = array();
        $root_encountered = false;

        // cleanup
        foreach($records as $row) {
            if($row != null) {
                if($row->parent_subgroup == - 1) {
                    $row->parent_subgroup = null;
                    $row->subgroup = 0;
                } 
                if($row->parent_subgroup === null) {
                    $root_encountered = true;
                }
                array_push($criteria, $row);
            }
        }

        if(!$root_encountered) {
            $row = (object) array(
                    'subgroup' => 0,
                    'parent_subgroup' => null,
                    'condition' => $a['criteria_group']->condition 
            );
            array_unshift($criteria, $row);
        }

        //strategy: keep a record keyed by subgroups of where they are rooted. 
        //if an entry exists for a previous subgroup but the parent subgroup conflicts
        //use the subgroup of the LAST subgroup rooted there. 
        //else update array

        $adjacency = array(0 => null); //parent
        foreach($criteria as $row) {
            if (isset($adjacency[$row->subgroup]) && $adjacency[$row->subgroup] != $row->parent_subgroup) {
                $preserved = array_reverse($adjacency, true); //need LAST subgroup rooted there
                foreach($preserved as $key=>$val) {
                    if ($val == $row->parent_subgroup) {
                        $row->subgroup = $key;
                        break;
                    }
                }
            } else {
                $adjacency[$row->subgroup] = $row->parent_subgroup;
            }
        }

PHP：通过递归迭代构建邻接表

PHP: Building an Adjacency List through Recursive Iteration

php

recursion

persistence

adjacency-list