先来相熟 php-parser 的 API
nikic/PHP-Parser 能够解析 PHP 代码并生成 AST，还反对批改 AST 再还原成PHP源码，从而实现元编程，可用来做 AOP 和动态代码查看等。Swoft 框架中 AOP 也是基于 PHP-parser 开发的。
https://github.com/nikic/PHP-Parser
首先应用 composer 装置 php-parser
composer require nikic/php-parser在代码中引入 autoload.php，开始测试代码
<?phprequire __DIR__ . '/vendor/autoload.php';use PhpParser\Error;use PhpParser\NodeDumper;use PhpParser\ParserFactory;// 定义一段PHP代码$code = <<<'CODE'<?phpfunction printLine($msg) { echo $msg, "\n";}printLine('Hello World!!!');CODE;// 创立一个解析器parser，须要指定优先版本$parser = (new ParserFactory)->create(ParserFactory::PREFER_PHP7);try { // 解析下面定义的PHP代码 $ast = $parser->parse($code);} catch (Error $error) { echo "Parse error: {$error->getMessage()}\n"; return;}$dumper = new NodeDumper;// 打印出生成的 ASTecho $dumper->dump($ast) . "\n========\n";打印出后果：
array( 0: Stmt_Function( attrGroups: array( ) byRef: false name: Identifier( name: printLine ) params: array( 0: Param( attrGroups: array( ) flags: 0 type: null byRef: false variadic: false var: Expr_Variable( name: msg ) default: null ) ) returnType: null stmts: array( 0: Stmt_Echo( exprs: array( 0: Expr_Variable( name: msg ) 1: Scalar_String( value: ) ) ) ) ) 1: Stmt_Expression( expr: Expr_FuncCall( name: Name( parts: array( 0: printLine ) ) args: array( 0: Arg( name: null value: Scalar_String( value: Hello World!!! ) byRef: false unpack: false ) ) ) ))AST 中各个构造阐明可参见文档：https://github.com/nikic/PHP-Parser/blob/master/doc/2_Usage_of_basic_components.markdown#node-tree-structure
下面打印的数组中别离是：
Stmt_Function -> PhpParser\Node\Stmt\Function_Stmt_Expression -> PhpParser\Node\Stmt\Expression
Function_ 有个 后缀是因为 Function 自身是保留字，包中还有很多命名带有 也都是这个起因。
Node 的类型阐明：
PhpParser\Node\Stmts are statement nodes, i.e. language constructs that do not return a value and can not occur in an expression. For example a class definition is a statement. It doesn't return a value and you can't write something likefunc(class A {});.PhpParser\Node\Exprs are expression nodes, i.e. language constructs that return a value and thus can occur in other expressions. Examples of expressions are$var(PhpParser\Node\Expr\Variable) andfunc()(PhpParser\Node\Expr\FuncCall).PhpParser\Node\Scalars are nodes representing scalar values, like'string'(PhpParser\Node\Scalar\String_),0(PhpParser\Node\Scalar\LNumber) or magic constants like__FILE__(PhpParser\Node\Scalar\MagicConst\File). AllPhpParser\Node\Scalars extendPhpParser\Node\Expr, as scalars are expressions, too.- There are some nodes not in either of these groups, for example names (
PhpParser\Node\Name) and call arguments (PhpParser\Node\Arg).
拜访并批改 Node：
// 拜访第0个元素 即Stmt_Function，一级一级向下拜访，最初赋值$ast[0]->stmts[0]->exprs[1]->value = '换行被替换了';// 拜访第1个元素 即Stmt_Expression$ast[1]->expr->args[0]->value->value = 'Hello World被替换了';echo $dumper->dump($ast) . "\n========\n";打印后果：
array( 0: Stmt_Function( attrGroups: array( ) byRef: false name: Identifier( name: printLine ) params: array( 0: Param( attrGroups: array( ) flags: 0 type: null byRef: false variadic: false var: Expr_Variable( name: msg ) default: null ) ) returnType: null stmts: array( 0: Stmt_Echo( exprs: array( 0: Expr_Variable( name: msg ) 1: Scalar_String( value: 换行被替换了 // 这里value被扭转了 ) ) ) ) ) 1: Stmt_Expression( expr: Expr_FuncCall( name: Name( parts: array( 0: printLine ) ) args: array( 0: Arg( name: null value: Scalar_String( value: Hello World被替换了 // 这里value也被改了 ) byRef: false unpack: false ) ) ) ))遍历 AST 中的 Node：
遍历 AST 须要指定一个拜访器，需实现几个办法，beforeTraverse 和 afterTraverse 是在开始遍历前和完结遍历后执行一次，enterNode 和 leaveNode 是每遍历到一个 Node 时执行一次。
interface NodeVisitor { public function beforeTraverse(array $nodes); public function enterNode(Node $node); public function leaveNode(Node $node); public function afterTraverse(array $nodes);}// NodeVisitorAbstract 是其抽象类class NodeVisitorAbstract implements NodeVisitor{ public function beforeTraverse(array $nodes) { return null; } public function enterNode(Node $node) { return null; } public function leaveNode(Node $node) { return null; } public function afterTraverse(array $nodes) { return null; }}use PhpParser\Node;use PhpParser\Node\Stmt\Function_;use PhpParser\NodeTraverser;use PhpParser\NodeVisitorAbstract;$traverser = new NodeTraverser();$traverser->addVisitor(new class extends NodeVisitorAbstract { public function enterNode(Node $node) { // 如果node是Function_类型时 if ($node instanceof Function_) { // Clean out the function body // 状况node的语句，即清空了函数体 $node->stmts = []; // 或者返回一个新的node // return new Function_("new_func"); } }});$ast = $traverser->traverse($ast);echo $dumper->dump($ast) . "\n========\n";输入：
array( 0: Stmt_Function( attrGroups: array( ) byRef: false name: Identifier( name: new_func ) params: array( ) returnType: null stmts: array( ) // stmts 被清空了 ) 1: Stmt_Expression( expr: Expr_FuncCall( name: Name( parts: array( 0: printLine ) ) args: array( 0: Arg( name: null value: Scalar_String( value: Hello World被替换了 ) byRef: false unpack: false ) ) ) ))输入批改后的 PHP 代码，即 Pretty Print
use PhpParser\PrettyPrinter;$prettyPrinter = new PrettyPrinter\Standard;echo $prettyPrinter->prettyPrintFile($ast);输入：
<?phpfunction printLine($msg){}printLine('Hello World被替换了');%函数体被清空了，并且第二个语句 printLine 中的参数被替换了。
有了这种能力，联合一些正文标注等，就能够在 PHP 代码在执行之前动静批改带有指定特色的 PHP代码的行为。
应用 PHP-parser 重写 PHP 类代码实现AOP：
参考文章：https://learnku.com/articles/14387/aop-design-rewrite-the-php...
该 AOP 加强的成果是在字符串前面减少一个叹号 !
入口 aop.php:
<?phprequire __DIR__ . '/vendor/autoload.php';require __DIR__ . '/ProxyVisitor.php';require __DIR__ . '/Test.php';use PhpParser\ParserFactory;use PhpParser\NodeTraverser;use PhpParser\NodeDumper;use PhpParser\PrettyPrinter\Standard;$file = './Test.php';$code = file_get_contents($file);$parser = (new ParserFactory())->create(ParserFactory::PREFER_PHP7);$ast = $parser->parse($code);$dumper = new NodeDumper;echo $dumper->dump($ast) . "\n========\n";$traverser = new NodeTraverser();$className = 'Test';$proxyId = uniqid();$visitor = new ProxyVisitor($className, $proxyId);$traverser->addVisitor($visitor);$proxyAst = $traverser->traverse($ast);if (!$proxyAst) { throw new \Exception(sprintf('Class %s AST optimize failure', $className));}$printer = new Standard();$proxyCode = $printer->prettyPrint($proxyAst);echo $proxyCode;eval($proxyCode);$class = $visitor->getClassName();$bean = new $class();echo $bean->show();PHP-Parser 的拜访器 ProxyVisitor.php
<?phprequire __DIR__ . '/vendor/autoload.php';use PhpParser\NodeVisitorAbstract;use PhpParser\Node;use PhpParser\Node\Expr\Closure;use PhpParser\Node\Expr\FuncCall;use PhpParser\Node\Expr\MethodCall;use PhpParser\Node\Expr\Variable;use PhpParser\Node\Name;use PhpParser\Node\Param;use PhpParser\Node\Scalar\String_;use PhpParser\Node\Stmt\Class_;use PhpParser\Node\Stmt\ClassMethod;use PhpParser\Node\Stmt\Return_;use PhpParser\Node\Stmt\TraitUse;use PhpParser\NodeFinder;use PhpParser\NodeDumper;class ProxyVisitor extends NodeVisitorAbstract{ protected $className; protected $proxyId; public function __construct($className, $proxyId) { $this->className = $className; $this->proxyId = $proxyId; } public function getProxyClassName(): string { return \basename(str_replace('\\', '/', $this->className)) . '_' . $this->proxyId; } public function getClassName() { return '\\' . $this->className . '_' . $this->proxyId; } /** * @return \PhpParser\Node\Stmt\TraitUse */ private function getAopTraitUseNode(): TraitUse { // Use AopTrait trait use node return new TraitUse([new Name('AopTrait')]); } public function leaveNode(Node $node) { echo "=====leaveNode=====\n"; // Proxy Class if ($node instanceof Class_) { // Create proxy class base on parent class echo "Class_ instance"; return new Class_($this->getProxyClassName(), [ 'flags' => $node->flags, 'stmts' => $node->stmts, 'extends' => new Name($this->className), ]); } // Rewrite public and protected methods, without static methods if ($node instanceof ClassMethod && !$node->isStatic() && ($node->isPublic() || $node->isProtected())) { $methodName = $node->name->toString(); echo "classmethod name ", $methodName , "\n"; // Rebuild closure uses, only variable $uses = []; foreach ($node->params as $key => $param) { if ($param instanceof Param) { $uses[$key] = new Param($param->var, null, null, true); } } $params = [ // Add method to an closure new Closure([ 'static' => $node->isStatic(), 'uses' => $uses, 'stmts' => $node->stmts, ]), new String_($methodName), new FuncCall(new Name('func_get_args')), ]; $stmts = [ new Return_(new MethodCall(new Variable('this'), '__proxyCall', $params)) ]; $returnType = $node->getReturnType(); if ($returnType instanceof Name && $returnType->toString() === 'self') { $returnType = new Name('\\' . $this->className); } return new ClassMethod($methodName, [ 'flags' => $node->flags, 'byRef' => $node->byRef, 'params' => $node->params, 'returnType' => $returnType, 'stmts' => $stmts, ]); } } public function afterTraverse(array $nodes) { echo "=====afterTraverse=====\n"; $addEnhancementMethods = true; $nodeFinder = new NodeFinder(); $nodeFinder->find($nodes, function (Node $node) use ( &$addEnhancementMethods ) { if ($node instanceof TraitUse) { foreach ($node->traits as $trait) { // Did AopTrait trait use ? if ($trait instanceof Name && $trait->toString() === 'AopTrait') { $addEnhancementMethods = false; break; } } } }); // Find Class Node and then Add Aop Enhancement Methods nodes and getOriginalClassName() method $classNode = $nodeFinder->findFirstInstanceOf($nodes, Class_::class); $addEnhancementMethods && array_unshift($classNode->stmts, $this->getAopTraitUseNode()); return $nodes; }}trait AopTrait{ /** * AOP proxy call method * 这个AOP增强就是往字符串前面加一个 ! * @param \Closure $closure * @param string $method * @param array $params * @return mixed|null * @throws \Throwable */ public function __proxyCall(\Closure $closure, string $method, array $params) { $res = $closure(...$params); if (is_string($res)) { $res .= '!'; } return $res; }}被代理的类 Test.php
<?phpclass Test{ public function show() { return 'hello world'; }}执行后，被加强的后果类为：
class Test_60b7bffeb7672 extends Test{ use AopTrait; public function show() { return $this->__proxyCall(function () { return 'hello world'; }, 'show', func_get_args()); }}执行后果：
hello world!Swoft 框架中的 AOP 实现原理
swoft 的 aop 也是基于 php-parser 来实现的，因为懒的搞 phpunit，在本是 testcase 的类上间接改代码手动调试了：
<?php declare(strict_types=1);namespace SwoftTest\Aop\Unit;require_once './vendor/autoload.php';use Swoft\Aop\Ast\Visitor\ProxyVisitor;use Swoft\Aop\BeiAopClass;use Swoft\Aop\Proxy;use Swoft\Proxy\Ast\Parser;use Swoft\Proxy\Exception\ProxyException;use Swoft\Proxy\Proxy as BaseProxy;use function class_exists;use function sprintf;use const PHP_EOL;class AopTest{ public function testProxyClass(): void { /* 源码在 https://github.com/swoft-cloud/swoft-aop/blob/master/src/Ast/Visitor/ProxyVisitor.php 实现了PhpParser的NodeVisitor接口，即定义了遍历ast的nodes时，解决每个node的具体形式。 */ $visitor = new ProxyVisitor(); $className = BaseProxy::newClassName(BeiAopClass::class, $visitor); $o = new $className; var_dump($o->MethodNull(1,'2', 3.0, 'xxxx')); }}$a = new AopTest();$a->testProxyClass();newClassName 办法如下：
<?phpclass Proxy{public static function newClassName(string $className, Visitor $visitor, string $suffix = ''): string { echo "被aop的类名:$className \n"; $cacheKey = $className . $suffix; if (isset(self::$caches[$cacheKey])) { return self::$caches[$cacheKey]; } $parser = new Parser(); // 给parser增加拜访器，即默认的ProxyVisitor $parser->addNodeVisitor(get_class($visitor), $visitor); $proxyCode = $parser->parse($className); echo "代理后的代码:\n $proxyCode \n"; $proxyName = $visitor->getProxyName(); $newClassName = $visitor->getProxyClassName(); // 要想让代理后的代码失效，能够写入文件，之后require文件失效 eval($proxyCode); // 或者间接eval这段代理后的代码 $proxyFile = sprintf('%s/%s.php', Sys::getTempDir(), $proxyName); $proxyCode = sprintf('<?php %s %s', PHP_EOL, $proxyCode); // Generate proxy class $result = file_put_contents($proxyFile, $proxyCode); if ($result === false) { throw new ProxyException(sprintf('Proxy file(%s) generate fail', $proxyFile)); } // Load new proxy class file. self::loadProxyClass($proxyFile); // Ensure proxy class is loaded if (!class_exists($newClassName)) { throw new ProxyException(sprintf('Proxy class(%s) is not exist!', $newClassName)); } // Add cache, mark has been required. self::$caches[$cacheKey] = $newClassName; return $newClassName; }失去类名，即可 new 之，依照原类的办法签名形式调用，即可失去代理后的成果。
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