/*
 * C++ Design Patterns: Command
 * Author: Jakub Vojvoda [github.com/JakubVojvoda]
 * 2016
 *
 * Source code is licensed under MIT License
 * (for more details see LICENSE)
 *
 */

#include <iostream>

/*
 * Receiver
 * knows how to perform the operations associated
 * with carrying out a request
 */
class Receiver
{
public:
 void action()
 {
 std::cout << "Receiver: execute action" << std::endl;
 }
 // ...
};

/*
 * Command
 * declares an interface for all commands
 */
class Command
{
public:
 virtual ~Command() {}
 virtual void execute() = 0;
 // ...

protected:
 Command() {}
};

/*
 * Concrete Command
 * implements execute by invoking the corresponding
 * operation(s) on Receiver
 */
class ConcreteCommand : public Command
{
public:
 ConcreteCommand( Receiver *r ) : receiver( r ) {}
 
 ~ConcreteCommand()
 {
 if ( receiver )
 {
 delete receiver;
 }
 }
 
 void execute()
 {
 receiver->action();
 }
 // ...
 
private:
 Receiver *receiver;
 // ...
};

/*
 * Invoker
 * asks the command to carry out the request
 */
class Invoker
{
public:
 void set( Command *c )
 {
 command = c;
 }
 
 void confirm()
 {
 if ( command )
 {
 command->execute(); 
 }
 }
 // ...

private:
 Command *command;
 // ...
};


int main()
{
 ConcreteCommand command( new Receiver() );
 
 Invoker invoker;
 invoker.set( &command );
 invoker.confirm();
 
 return 0;
}