PHP-CPP是一個用于開發PHP擴展的C++庫。本節講解如何在C++中實現PHP類。

類和對象

類和對象

怎樣在PHP-CPP里寫出PHP的類呢？很簡單，看下面的例子：
main.cpp

/*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/ #include <time.h> #include <phpcpp.h>/*** Counter class that can be used for counting*/ class Counter : public Php::Base { private:/*** The initial value* @var int*/int _value = 0;public:/*** C++ constructor and destructor*/Counter() = default;virtual ~Counter() = default;/*** Update methods to increment or decrement the counter* Both methods return the NEW value of the counter* @return int*/Php::Value increment() { return ++_value; }Php::Value decrement() { return --_value; }/*** Method to retrieve the current counter value* @return int*/Php::Value value() const { return _value; }//類的靜態成員函數static Php::Value gettime() {return time(NULL);} };/*** Switch to C context to ensure that the get_module() function* is callable by C programs (which the Zend engine is)*/ extern "C" {/*** Startup function that is called by the Zend engine * to retrieve all information about the extension* @return void**/PHPCPP_EXPORT void *get_module() {// 必須是static類型，因為擴展對象需要在PHP進程內常駐內存static Php::Extension extension("helloworld", "1.0.0");//初始化導出類Php::Class<Counter> counter("Counter");//注冊導出類的可訪問普通函數counter.method<&Counter::increment> ("increment");counter.method<&Counter::decrement> ("decrement");counter.method<&Counter::value> ("value");//注冊導出類的可訪問靜態函數counter.method<&Counter::gettime>("gettime");//注冊導出類，使用右值引用方式，優化資源使用extension.add(std::move(counter));// 返回擴展對象指針return extension;} }

首先，C++類必須繼承自Php::Base；其次，當我們將類添加到擴展對象時，還必須指定要從PHP訪問的所有方法；最后再注冊導出類。

我們先測試：

/*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/ $counter = new Counter; echo 'result of increment() = '. $counter->increment() . PHP_EOL; echo 'result of increment() = '. $counter->increment() . PHP_EOL; echo 'result of decrement() = '. $counter->decrement() . PHP_EOL; echo 'result of value() = '. $counter->value() . PHP_EOL; echo 'result of gettime() = '. Counter::gettime() . PHP_EOL;

輸出：

result of increment() = 1 result of increment() = 2 result of decrement() = 1 result of value() = 1 result of gettime() = 1531621728

訪問修飾符

我們還可以對導出的方法添加訪問修飾符：

//初始化導出類 Php::Class<Counter> counter("Counter");//注冊導出類的可訪問普通函數 counter.method<&Counter::increment> ("increment", Php::Private, {Php::ByVal("a", Php::Type::Numeric) }); counter.method<&Counter::decrement> ("decrement", Php::Protected, {Php::ByVal("a", Php::Type::Numeric) }); counter.method<&Counter::value> ("value");

Php::Class::method第二個參數支持設置訪問修飾符，默認是public；第三個參數和普通函數一樣，支持設置參數類型。

支持的訪問修飾符：

extern PHPCPP_EXPORT const int Static; extern PHPCPP_EXPORT const int Abstract; extern PHPCPP_EXPORT const int Final; extern PHPCPP_EXPORT const int Public; extern PHPCPP_EXPORT const int Protected; extern PHPCPP_EXPORT const int Private; extern PHPCPP_EXPORT const int Const;

有一點需要注意：C++里要導出的方法，必須全是Public的， 即使我們在PHP中將它們標記為私有或受保護。因為我們寫的方法由PHP-CPP庫調用，如果將它們設為私有，它們將對庫不可見。

抽象類、Final類

聲明類為Final很簡單，只需要在初始化導出類的時候聲明一下即可：

Php::Class<Counter> counter("Counter", Php::Final);

那么怎么聲明一個抽象類呢？上面的例子里Php::Class::method都傳入了真正的C ++方法的地址，但是抽象方法通常沒有實現，那么我們需要怎么提供指向方法的指針？幸運的是，在PHP-CPP里注冊抽象方法不用提供指向C ++方法的指針。

示例：
抽象類原申明：

/*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/ #include <phpcpp.h>//類聲明 class MyAbstract : public Php::Base{};extern "C" {PHPCPP_EXPORT void *get_module() {// 必須是static類型，因為擴展對象需要在PHP進程內常駐內存static Php::Extension extension("helloworld", "1.0.0");//初始化導出類Php::Class<MyAbstract> my_abstract("MyAbstract", Php::Abstract);//注冊抽象方法：如果不給出C++方法的地址，該方法自動變成抽象方法my_abstract.method("myAbstractMethod", { Php::ByVal("a", Php::Type::String, true) });extension.add(std::move(my_abstract));// 返回擴展對象指針return extension;} }

我們在test.php嘗試去實例化MyAbstract類，提示：

PHP Fatal error: Uncaught Error: Cannot instantiate abstract class MyAbstract

注：官方示例里初始化導出類里沒有加Php::Abstract,測試的時候發現還是可以實例化的，只是調用抽象方法才報錯。

構造函數和析構函數

在C++代碼里，PHP的構造函數和析構函數本質上是普通方法。明白了這點，就不難實現了。

示例：

/*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/ #include <phpcpp.h>/*** Simple counter class*/ class Counter : public Php::Base { private:/*** Internal value* @var int*/int _value = 0;public:/*** c++ constructor*/Counter() = default;/*** c++ destructor*/virtual ~Counter() = default;/*** php "constructor"* @param params*/void __construct(Php::Parameters &params){// copy first parameter (if available)if (!params.empty()) _value = params[0];}/*** functions to increment and decrement*/Php::Value increment() { return ++_value; }Php::Value decrement() { return --_value; }Php::Value value() const { return _value; } };/*** Switch to C context so that the get_module() function can be* called by C programs (which the Zend engine is)*/ extern "C" {/*** Startup function for the extension* @return void**/PHPCPP_EXPORT void *get_module() {static Php::Extension myExtension("my_extension", "1.0");// description of the class so that PHP knows which methods are accessiblePhp::Class<Counter> counter("Counter");counter.method<&Counter::__construct>("__construct");counter.method<&Counter::increment>("increment");counter.method<&Counter::decrement>("decrement");counter.method<&Counter::value>("value");// add the class to the extensionmyExtension.add(std::move(counter));// return the extensionreturn myExtension;} }

如果需要構造函數為私有的，只需要在注冊的時候加個flag：

counter.method<&Counter::__construct>("__construct", Php::Private);

如果要禁止被clone，可以：

// alternative way to make an object unclonable counter.method("__clone", Php::Private);

接口

接口(Interface)由于不需要具體方法的實現，我們可以通過與定義類的方式類似的方式來實現。唯一的區別是我們不使用Php::Class<YourClass>，而是一個Php::Interface實例。

//初始化 Php::Interface interface("MyInterface");//添加成員方法 interface.method("myMethod", { Php::ByVal("value", Php::Type::String, true) });//注冊到擴展 extension.add(std::move(interface));

繼承

implement 實現

我們除了可以在PHP代碼去實現接口或者繼承類，也可以在C++里實現。該Php::Class<YourClass>對象有extends()和implements()，可用于指定基類和實現的接口。我們需要傳入之前配置的類或接口。我們來看一個例子。

/*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/ #include <phpcpp.h> #include <iostream>class MyClass : public Php::Base {public:Php::Value myMethod(Php::Parameters &params){Php::out << "MyClass" << std::endl;return params;} };extern "C" {PHPCPP_EXPORT void *get_module() {static Php::Extension extension("helloworld", "1.0.0");//定義接口Php::Interface interface("MyInterface");interface.method("myMethod", { Php::ByVal("value", Php::Type::String, true) });extension.add(std::move(interface));// 注冊一個自定義類Php::Class<MyClass> myClass("MyClass");// 實現接口定義myClass.implements(interface);myClass.method<&MyClass::myMethod>("myMethod", {Php::ByVal("value", Php::Type::String, true) });extension.add(std::move(myClass));// 返回擴展對象指針return extension;} }

測試：

$obj = new MyClass(); var_dump($obj->myMethod(11));

extends 繼承

PHP的繼承與C++的繼承沒有直接關系，必須顯示使用Php::Class::extends()進行繼承。

還是接著上面的例子說明。

/*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/ #include <phpcpp.h> #include <iostream>class MyClass : public Php::Base {public:Php::Value myMethod(Php::Parameters &params){Php::out << "MyClass" << std::endl;return params;} };class MySubClass : public Php::Base{ };extern "C" {PHPCPP_EXPORT void *get_module() {static Php::Extension extension("helloworld", "1.0.0");//定義接口Php::Interface interface("MyInterface");interface.method("myMethod", { Php::ByVal("value", Php::Type::String, true) });// 注冊一個自定義類Php::Class<MyClass> myClass("MyClass");// 實現接口定義myClass.implements(interface);myClass.method<&MyClass::myMethod>("myMethod", {Php::ByVal("value", Php::Type::String, true) });Php::Class<MySubClass> mySubClass("MySubClass");mySubClass.extends(myClass);extension.add(std::move(interface));extension.add(std::move(mySubClass));extension.add(std::move(myClass));// 返回擴展對象指針return extension;} }

注：注冊類(extension.add)需要放到extends方法的后面，也就是不能先注冊父類再使用extends，否則無法繼承。建議實際編程的時候注冊統一放到最后面。

魔術方法

在PHP-CPP里，僅__construct()需要顯示的在get_module()里注冊，其他的魔術方法像__get()、__set()、__call()等都不需要注冊。

/*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/ #include <phpcpp.h>/*** A sample class, that has some pseudo properties that map to native types*/ class User : public Php::Base { private:/*** Name of the user* @var std::string*/std::string _name;/*** Email address of the user* @var std::string*/std::string _email;public:/*** C++ constructor and C++ destructpr*/User() = default;virtual ~User() = default;/*** Get access to a property* @param name Name of the property* @return Value Property value*/Php::Value __get(const Php::Value &name){// check if the property name is supportedif (name == "name") return _name;if (name == "email") return _email;// property not supported, fall back on defaultreturn Php::Base::__get(name);}/*** Overwrite a property* @param name Name of the property* @param value New property value*/void __set(const Php::Value &name, const Php::Value &value) {// check the property nameif (name == "name") {// store member_name = value.stringValue();}// we check emails for validityelse if (name == "email"){// store the email in a stringstd::string email = value;// must have a '@' character in itif (email.find('@') == std::string::npos) {// email address is invalid, throw exceptionthrow Php::Exception("Invalid email address");}// store the member_email = email;}// other properties fall back to defaultelse{// call defaultPhp::Base::__set(name, value);}}/*** Check if a property is set* @param name Name of the property* @return bool*/bool __isset(const Php::Value &name) {// true for name and email addressif (name == "name" || name == "email") return true;// fallback to defaultreturn Php::Base::__isset(name);}/*** Remove a property* @param name Name of the property to remove*/void __unset(const Php::Value &name){// name and email can not be unsetif (name == "name" || name == "email") {// warn the user with an exception that this is impossiblethrow Php::Exception("Name and email address can not be removed");}// fallback to defaultPhp::Base::__unset(name);} };/*** Switch to C context to ensure that the get_module() function* is callable by C programs (which the Zend engine is)*/ extern "C" {/*** Startup function that is called by the Zend engine * to retrieve all information about the extension* @return void**/PHPCPP_EXPORT void *get_module() {// extension objectstatic Php::Extension myExtension("my_extension", "1.0");// description of the class so that PHP knows // which methods are accessiblePhp::Class<User> user("User");// add the class to the extensionmyExtension.add(std::move(user));// return the extensionreturn myExtension;} }

測試：

<?php /*** User: 公眾號: 飛鴻影的博客(fhyblog)* Date: 2018/7*/// initialize user and set its name and email address $user = new User(); $user->name = "John Doe"; $user->email = "john.doe@example.com";// show the email address echo($user->email."\n");// remove the email address (this will cause an exception) unset($user->email); ?>

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轉載于:https://www.cnblogs.com/52fhy/p/9388764.html

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