先来熟悉 php-parser 的 API
nikic/PHP-Parser 可以解析 PHP 代码并生成 AST，还支持修改 AST 再还原成PHP源码，从而实现元编程，可用来做 AOP 和静态代码检查等。Swoft 框架中 AOP 也是基于 PHP-parser 开发的。
https://github.com/nikic/PHP-Parser
首先使用 composer 安装 php-parser
composer require nikic/php-parser在代码中引入 autoload.php，开始测试代码
create(ParserFactory::PREFER_PHP7);
try {
// 解析上面定义的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";
打印出结果：
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 中各个结构说明可参见文档：https://github.com/nikic/PHP-Parser/blob/master/doc/2_Usage_of_basic_components.markdown#node-tree-structure
上面打印的数组中分别是：
Stmt_Function -> PhpParser\Node\Stmt\Function_Stmt_Expression -> PhpParser\Node\Stmt\Expression
Function_ 有个 后缀是因为 Function 本身是保留字，包中还有很多命名带有 也都是这个原因。
Node 的类型说明：
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).
访问并修改 Node：
// 访问第0个元素 即Stmt_Function，一级一级向下访问，最后赋值
$ast[0]->stmts[0]->exprs[1]->value = '换行被替换了';
// 访问第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";打印结果：
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被改变了
)
)
)
)
)
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 需要指定一个访问器，需实现几个方法，beforeTraverse 和 afterTraverse 是在开始遍历前和结束遍历后执行一次，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
// 情况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";
输出：
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
)
)
)
)
)输出修改后的 PHP 代码，即 Pretty Print
use PhpParser\PrettyPrinter;
$prettyPrinter = new PrettyPrinter\Standard;
echo $prettyPrinter->prettyPrintFile($ast);输出：
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，结合一些注释标注等，就可以在 PHP 代码在执行之前动态修改带有指定特征的 PHP代码的行为。
使用 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 增强的效果是在字符串后面增加一个叹号 !
入口 aop.php:
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 的访问器 ProxyVisitor.php
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加强就是往字符串后面加一个 !
* @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
执行后，被增强的结果类为：
class Test_60b7bffeb7672 extends Test
{
use AopTrait;
public function show()
{
return $this->__proxyCall(function () {
return 'hello world';
}, 'show', func_get_args());
}
}执行结果：
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，由于懒的搞 phpunit，在本是 testcase 的类上直接改代码手动调试了：
MethodNull(1,'2', 3.0, 'xxxx'));
}
}
$a = new AopTest();
$a->testProxyClass();
newClassName 方法如下：
addNodeVisitor(get_class($visitor), $visitor);
$proxyCode = $parser->parse($className);
echo "代理后的代码:\n $proxyCode \n";
$proxyName = $visitor->getProxyName();
$newClassName = $visitor->getProxyClassName();
// 要想让代理后的代码生效，可以写入文件，之后require文件生效
eval($proxyCode);
// 或者直接eval这段代理后的代码
$proxyFile = sprintf('%s/%s.php', Sys::getTempDir(), $proxyName);
$proxyCode = sprintf('得到类名，即可 new 之，按照原类的方法签名方式调用，即可得到代理后的效果。
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