Headfirst设计模式的C++实现——组合模式(Composite)

Posted 2020-07-23 Ren.Yu

menu_component.h

 1 #ifndef _MENU_COMPONENT_H_
 2 #define _MENU_COMPONENT_H_
 3 
 4 #include <string>
 5 
 6 class MenuComponent {
 7 public:
 8     class Iterator {
 9     public:
10         virtual bool has_next() = 0;
11     
12         virtual MenuComponent *next() = 0; 
13     };
14     
15     MenuComponent( const std::string &_name, const std::string &_description ) :
16         name(_name), description(_description) {}
17     
18     const std::string& get_name() { return name; }
19     
20     const std::string& get_description() { return description; }
21     
22     virtual void print() = 0;
23     
24     virtual Iterator *get_iterator() = 0;
25 private:
26     std::string name;
27     std::string description;
28 };
29 #endif

menu_item.h

 1 #ifndef _MENU_ITEM_H_
 2 #define _MENU_ITEM_H_
 3 
 4 #include "menu_component.h"
 5 #include <iostream>
 6 
 7 class MenuItem : public MenuComponent {
 8 public:
 9     MenuItem( const std::string &_name, const std::string &_description, double _price, bool _vegetarian ) :
10         MenuComponent( _name, _description ), price(_price), vegetarian(_vegetarian) {} 
11   
12     void print() {
13         std::cout << get_name() << " "
14                   << get_description() << " "
15                   << get_price() << " "
16                   << is_vegetarian() << std::endl;
17     }
18     
19     double get_price() { return price; }
20     
21     bool is_vegetarian() { return vegetarian; }
22     
23     Iterator *get_iterator() { return NULL; }
24 private:
25     double price;    
26     bool vegetarian;
27 };
28 #endif

menu.h

 1 #ifndef _MENU_H_
 2 #define _MENU_H_
 3 
 4 #include "ivector.h"
 5 #include <stack>
 6 
 7 class Menu : public MenuComponent{
 8 public:
 9     Menu( const std::string &_name, const std::string &_description ) :
10         MenuComponent( _name, _description ),
11         _iterator( menu_components.get_iterator() ) {}
12 
13     void add( MenuComponent* component ) { menu_components.add( component ); }
14 
15     void print() { std::cout << get_name() << " " << get_description() << std::endl; }
16 
17     Iterator *get_iterator() { return &_iterator; }
18 
19 private:
20     IVector menu_components;
21     
22     class _Iterator : public Iterator {
23     public:
24         _Iterator( Iterator *it) { s.push(it); }
25 
26         bool has_next() {
27             if ( s.empty() ) { return false; }
28             if ( s.top()->has_next() ) { return true; }
29             s.pop();
30             return has_next();
31         }
32 
33         MenuComponent *next() {
34             if ( has_next() ) {
35                 MenuComponent *next = s.top()->next();
36                 if ( NULL != next->get_iterator() ) { s.push( next->get_iterator() );}
37                 return next;
38             }
39         }
40     private:
41         std::stack<Iterator *> s;
42     } _iterator;
43 };
44 #endif

ivector.h

 1 #ifndef _IVECTOR_H_
 2 #define _IVECTOR_H_
 3 
 4 #include "menu_component.h"
 5 #include <vector>
 6 
 7 class IVector{
 8 public:
 9     IVector() : data_iterator( *this ) {}
10 
11     void add( MenuComponent *component ) { data_v.push_back( component ); }
12 
13     MenuComponent::Iterator *get_iterator() { return &data_iterator; }
14 private:
15     std::vector<MenuComponent *> data_v;
16     
17     class _Iterator : public MenuComponent::Iterator {
18     public:
19         _Iterator (IVector &_ivector) : ivector(_ivector), pos(0) {}
20         
21         bool has_next() { return pos < ivector.data_v.size(); }
22         
23         MenuComponent *next() { return ivector.data_v[pos++]; }
24     private:
25         int pos;
26         
27         IVector &ivector;
28     } data_iterator;
29 };
30 #endif

main.cpp

 1 #include "menu_item.h"
 2 #include "menu.h"
 3 
 4 int main() {
 5     
 6     Menu *p = new Menu("total", "total");
 7     p->add(new MenuItem("MenuItem 1", "test description", 9.4, true));
 8     p->add(new MenuItem("MenuItem 2", "test description", 9.4, true));
 9 
10     Menu *p1 = new Menu("sub menu", "test description");
11     p1->add(new MenuItem("MenuItem 3", "test description", 9.4, true));
12     p1->add(new MenuItem("MenuItem 4", "test description", 9.4, true));
13     p->add(p1);
14     
15     MenuComponent::Iterator *it = p->get_iterator();
16     while ( it->has_next() ) {
17         MenuItem *menu_item = (MenuItem *)it->next();
18         menu_item->print();        
19     }
20 
21     return 0;
22 }