PHP 實現規則引擎

1、規則引擎簡介

我們在寫業務代碼經常遇到需要一大堆if/else，會導致代碼可讀性大大降低，有沒有一種方法可以避免代碼中出現大量的判斷語句呢？答案是用規則引擎。

規則引擎是一種推理引擎，它是根據已有的事實，從規則知識庫中匹配規則，並處理存在衝突的規則，執行最後篩選通過的規則。因此，規則引擎是人工智能（AI）研究領域的一部分，具有一定的選擇判斷性、人工智能性和富含知識性。

2、核心思想

規則就是一堆條件傳入，這些條件之間有與或的邏輯關係，根據引擎判斷和之後，進行後續的動作。

3、基本架構思想

規則文件 + data => 後端解析condition => action

流程圖

 

image.png

4、UML圖

rule.png

5、用php實現

目錄結構

image.png

首先規則文件在此用目前流行的json文件表示
舉例 rule.json

{
  "condition": {
    "1": {
      "type": "tag",
      "con": "user = 1"
    },
    "2": {
      "type": "tag",
      "con": "user > 1"
    }
  },
  "logical": "1 & 2",
  "action": ["action1", "action2"]
}

ConditionInterface

<?php
interface ConditionInterface {

    public function __construct($condition);

    public function check(&$data);
}

ActionInterface

interface ActionInterface {

    public function call();
}

condition容器

<?php
class conContainer {

    private $conditions = [];
    private $results = [];
    private $logicalArr;

    public function setLogical($logical) {
        $this->logicalArr = explode(' ', $logical);
    }

    public function __set($param, $condition)
    {
        $this->conditions[$param] = $condition;
    }

    public function check(&$data) {
        //docheck
        foreach ($this->conditions as $param => $condition) {
            $this->results[$param] = $condition->check($data);
        }
        $i = 0;
        $commandArr = $this->logicalArr;
        foreach ($commandArr as &$str) {
            if (preg_match('/^\d+$/', $str)) {
                $str = $this->results[$i+1];
                $i++;
            }
        }
        $command = implode('', $commandArr);
        $result = eval('return '.$command.';');
        return $result;
    }
}

規則類

<?php

class check_rule_class {

}

class rule{

    public static function check($rule, $obj) {
        $res = false;
        if (preg_match("/^\(([a-zA-Z0-9_]+)\s*(((\=|\>|\<|\>=|\<=)\s*\'?[a-zA-Z0-9\-\s\:]+\'?)|(in\s*\[(\'?[a-zA-Z0-9\-]+\'?\s*\,?\s*)+\]))\)$/", $rule, $matches)) {
            $attribute = $matches[1];
            if (strpos($rule, 'in') !== false) {
                $rArr = explode('in', $rule);
                $paramStr = str_replace(array('[', ']', ')', ' ', '\'', '\''), '', $rArr[1]);
                $paramArr = explode(',',$paramStr);
                $res = in_array($obj->$attribute, $paramArr);
            } else {
                $r = $rule;
                if (preg_match('/[a-zA-Z0-9_]+\s*=/', $rule, $params)) $r = str_replace('=', '==', $rule);
                $atibute = $obj->$attribute;
                $res = eval('return ($atibute'.str_replace($attribute, '', substr($r, 1)).";");
            }
        }
        return $res;
    }

    public static function check_rule($ruleStr, $ruleClass) {
        $GLOBALS['log']->fatal('start-check-rule-------'.$ruleStr);
        if (preg_match_all("/\([a-zA-Z0-9_]+\s*(((=|\>|\<|\>=|\<=)\s*\'?[a-zA-Z0-9\-\s\:]+\'?)|(in\s*\[(\'?[a-zA-Z0-9\-]+\'?\s*\,?\s*)+\]))\)/", $ruleStr, $rules)) {
            foreach ($rules[0] as $rule) {
                $ruleRes = self::check($rule, $ruleClass);
                $ruleStr = str_replace($rule, (int)$ruleRes, $ruleStr);
            }
            $GLOBALS['log']->fatal('the-end-rule-----'.$ruleStr);
            if (!preg_match('/[^(0|1|and|or|!|\(|\)|\s)]/', $ruleStr)) {
                return eval('return '.str_replace(array('and', 'or'), array(' and ', ' or '), $ruleStr).";");
            }
        }
        return false;
    }
}

/**
 * 調用示例
 $class = new check_rule_class();
$class->a = '2';
$class->b = 5;
$res = rule::check_rule("!(a=2) or (b in [2, '5'])", $class);
var_dump($res); */

入口文件

<?php

require_once 'rule.php';
require_once 'conContainer.php';

$json = file_get_contents('rule.json');
$arr = json_decode($json, true);
$conContainer = new conContainer();
$conContainer->setLogical($arr['logical']);

foreach ($arr['condition'] as $k => $condition) {
    $file = $condition['type'];
    require_once 'condition/'.$file.'.php';
    $conContainer->$k = new $file($condition['con']);
}


$actClasses = $arr['action'];
$actions = [];
foreach ($actClasses as $actClass) {
    require_once 'action/'.$actClass.'.php';
    $actions[] = new $actClass();
}
$rule = new Rule($conContainer, $actions);
$rule->run();