PHP 实现规则引擎
1、规则引擎简介
我们在写业务代码经常遇到需要一大堆if/else，会导致代码可读性大大降低，有没有一种方法可以避免代码中出现大量的判断语句呢？答案是用规则引擎。
规则引擎是一种推理引擎，它是根据已有的事实，从规则知识库中匹配规则，并处理存在冲突的规则，执行最后筛选通过的规则。因此，规则引擎是人工智能（AI）研究领域的一部分，具有一定的选择判断性、人工智能性和富含知识性。
2、核心思想
规则就是一堆条件传入，这些条件之间有与或的逻辑关系，根据引擎判断和之后，进行后续的动作。
3、基本架构思想
规则文件 + data => 后端解析condition => action
流程图
image.png
4、UML图
rule.png
5、用php实现
目录结构
image.png
首先规则文件在此用目前流行的json文件表示
举例 rule.json
{
"condition": {
"1": {
"type": "tag",
"con": "user = 1"
},
"2": {
"type": "tag",
"con": "user > 1"
}
},
"logical": "1 & 2",
"action": ["action1", "action2"]
}
ConditionInterface
ActionInterface
interface ActionInterface {
public function call();
}
condition容器
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;
}
}
规则类
|\<|\>=|\<=)\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;
}
}
/**
* 调用示例
$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
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();