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
<?php
require __DIR__ . '/vendor/autoload.php';
use PhpParser\Error;
use PhpParser\NodeDumper;
use PhpParser\ParserFactory;
// 定义一段 PHP 代码
$code = <<<'CODE'
<?php
function printLine($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 AST
echo $dumper->dump($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\Stmt
s 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\Expr
s 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\Scalar
s 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\Scalar
s 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:
<?php
function 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:
<?php
require __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
<?php
require __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
<?php
class 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:
<?php
class 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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