command.c

Design Pattern C Source Code

/*
*/
#include "List.H"

class Document {
  public:
    Document(const char*);
    void Open();
    void Paste();
};

class Application {
  public:
    Application();
    void Add(Document*);
};
/*
*/
class Command {
public:
    virtual ~Command();

    virtual void Execute() = 0;
protected:
    Command();
};
/*
*/
class OpenCommand : public Command {
public:
    OpenCommand(Application*);

    virtual void Execute();
protected:
    virtual const char* AskUser();
private:
    Application* _application;
    char* _response;
};
/*
*/
OpenCommand::OpenCommand (Application* a) {
    _application = a;
}
/*
*/
void OpenCommand::Execute () {
    const char* name = AskUser();

    if (name != 0) {
        Document* document = new Document(name);
        _application->Add(document);
        document->Open();
    }
}
/*
*/
class PasteCommand : public Command {
public:
    PasteCommand(Document*);

    virtual void Execute();
private:
    Document* _document;
};
/*
*/
PasteCommand::PasteCommand (Document* doc) {
    _document = doc;
}

void PasteCommand::Execute () {
    _document->Paste();
}
/*
*/
template <class Receiver>
class SimpleCommand : public Command {
public:
    typedef void (Receiver::* Action)();

    SimpleCommand(Receiver* r, Action a) :
        _receiver(r), _action(a) { }

    virtual void Execute();
private:
    Action _action;
    Receiver* _receiver;
};
/*
*/
template <class Receiver>
void SimpleCommand<Receiver>::Execute () {
    (_receiver->*_action)();
}
/*
*/
class MyClass {
public:
  void Action();
};
void dummy () {
/*
*/
MyClass* receiver = new MyClass;
// ...
Command* aCommand =
    new SimpleCommand<MyClass>(receiver, &MyClass::Action);
// ...
aCommand->Execute();
/*
*/
}
/*
*/
class MacroCommand : public Command {
public:
    MacroCommand();
    virtual ~MacroCommand();

    virtual void Add(Command*);
    virtual void Remove(Command*);

    virtual void Execute();
private:
    List<Command*>* _cmds;
};
/*
*/
void MacroCommand::Execute () {
    ListIterator<Command*> i(_cmds);

    for (i.First(); !i.IsDone(); i.Next()) {
        Command* c = i.CurrentItem();
        c->Execute();
    }
}
/*
*/
void MacroCommand::Add (Command* c) {
    _cmds->Append(c);
}

void MacroCommand::Remove (Command* c) {
    _cmds->Remove(c);
}
/*
*/