设计模式9——组合模式

组合模式中，整体和部分可以同等看待，基类设定一个节点接口，可以派生出叶子节点和非叶子节点。叶子节点不能添加节点，非叶子节点可以添加，组成一个典型的树形结构。

组合模式在游戏引擎的渲染树中应用很广泛。

Composite.h内容

 1 #ifndef Composite_H_H
 2 #define Composite_H_H
 3
 4 #include<iostream>
 5 #include<vector>
 6 using namespace std;
 7
 8 class Composite
 9 {
10 public:
11     Composite(string str) : name(str) {}
12     virtual ~Composite() {}
13     virtual void add(Composite *composite) = 0;
14     virtual void display() = 0;
15 protected:
16     string name;
17 };
18
19 class Leaf : public Composite
20 {
21 public:
22     Leaf(string str) : Composite(str) {}
23     virtual void add(Composite *composite) {}
24     virtual void display() { cout << name << " "; }
25 private:
26
27 };
28
29 class Component : public Composite
30 {
31 public:
32     Component(string str) : Composite(str) { }
33     virtual void add(Composite *composite) { vecChildren.push_back(composite); }
34     virtual void display(){
35         cout << name << " " << endl;
36         for(size_t i=0; i<vecChildren.size(); ++i){
37             vecChildren[i]->display();
38         }
39     }
40 private:
41     vector<Composite*> vecChildren;
42 };
43
44 void CompositeTest()
45 {
46     Composite *com1 = new Component("A");
47     Composite *leaf1 = new Leaf("B");
48     Composite *leaf2 = new Leaf("C");
49     com1->add(leaf1);
50     com1->add(leaf2);
51
52     Composite *com2 = new Component("D");
53     Composite *leaf4 = new Leaf("E");
54     Composite *leaf5 = new Leaf("F");
55     com2->add(leaf4);
56     com2->add(leaf5);
57
58     com1->add(com2);
59
60     com1->display();
61
62 }
63
64 #endif