php实现规则引擎

PHP实现规则引擎的方法

使用Symfony ExpressionLanguage组件

Symfony的ExpressionLanguage组件允许在PHP中解析和执行表达式，适合简单规则引擎的实现。

安装组件：

composer require symfony/expression-language

示例代码：

use Symfony\Component\ExpressionLanguage\ExpressionLanguage;

$language = new ExpressionLanguage();
$result = $language->evaluate('user.age > 18 and user.creditScore > 700', [
    'user' => [
        'age' => 25,
        'creditScore' => 720
    ]
]);

实现自定义规则引擎类

创建可扩展的规则引擎类处理复杂业务逻辑：

class RuleEngine {
    private $rules = [];

    public function addRule($name, callable $condition, callable $action) {
        $this->rules[$name] = [
            'condition' => $condition,
            'action' => $action
        ];
    }

    public function execute($context) {
        foreach ($this->rules as $rule) {
            if ($rule['condition']($context)) {
                $rule['action']($context);
            }
        }
    }
}

// 使用示例
$engine = new RuleEngine();
$engine->addRule('discount_rule', 
    fn($order) => $order['total'] > 1000,
    fn($order) => $order['discount'] = $order['total'] * 0.1
);

使用Ruler库

Ruler是一个专门为PHP设计的规则引擎库，提供更专业的规则管理功能。

安装：

composer require hoa/ruler

示例用法：

use Hoa\Ruler\Ruler;

$ruler = new Ruler();
$rule = 'user.age > 18 and user.hasPremiumAccount = true';
$context = [
    'user' => [
        'age' => 20,
        'hasPremiumAccount' => true
    ]
];

if ($ruler->assert($rule, $context)) {
    // 规则匹配时执行的操作
}

基于数据库的规则存储

将规则存储在数据库中可以动态修改规则而不需修改代码：

// 假设rules表包含condition和action字段
$pdo = new PDO('mysql:host=localhost;dbname=app', 'user', 'pass');
$stmt = $pdo->query("SELECT condition, action FROM rules WHERE active = 1");

while ($rule = $stmt->fetch()) {
    if (eval("return {$rule['condition']};")) {
        eval($rule['action']);
    }
}

实现规则优先级和停止机制

增强规则引擎功能，支持优先级和规则链中断：

class AdvancedRuleEngine {
    private $rules = [];

    public function addRule($name, $priority, callable $condition, callable $action, $stopOnMatch = false) {
        $this->rules[] = [
            'name' => $name,
            'priority' => $priority,
            'condition' => $condition,
            'action' => $action,
            'stopOnMatch' => $stopOnMatch
        ];

        usort($this->rules, fn($a, $b) => $b['priority'] <=> $a['priority']);
    }

    public function execute($context) {
        foreach ($this->rules as $rule) {
            if ($rule['condition']($context)) {
                $rule['action']($context);
                if ($rule['stopOnMatch']) break;
            }
        }
    }
}

这些方法提供了从简单到复杂的PHP规则引擎实现方案，可根据项目需求选择合适的实现方式。对于企业级应用，建议考虑专门的规则引擎解决方案如Drools，或使用Symfony ExpressionLanguage等成熟组件。