c++如何实现组合设计模式(Composite)_c++处理树形结构的统一接口

class Component {
public:
    virtual ~Component() = default;
    virtual void operation() const = 0;
    virtual void add(Component* component) {
        throw std::runtime_error("Not supported.");
    }
    virtual void remove(Component* component) {
        throw std::runtime_error("Not supported.");
    }
    virtual Component* getChild(int index) {
        throw std::runtime_error("Not supported.");
    }
};

class Leaf : public Component {
public:
    void operation() const override {
        std::cout << "Leaf operation.\n";
    }
};
<p>class Composite : public Component {
private:
std::vector<Component*> children;</p><p>public:
void operation() const override {
std::cout << "Composite operation:\n";
for (const auto& child : children) {
child->operation();
}
}</p><pre class="brush:php;toolbar:false;"><pre class="brush:php;toolbar:false;">void add(Component* component) override {
    children.push_back(component);
}

void remove(Component* component) override {
    children.erase(
        std::remove(children.begin(), children.end(), component),
        children.end()
    );
}

Component* getChild(int index) override {
    if (index < 0 || index >= children.size()) return nullptr;
    return children[index];
}

int main() {
    Composite root;
    Leaf leaf1, leaf2;
    Composite subNode;
<pre class="brush:php;toolbar:false;"><pre class="brush:php;toolbar:false;">subNode.add(&leaf1);
root.add(&subNode);
root.add(&leaf2);

root.operation();  // 统一调用，自动遍历
return 0;

Composite operation:
Composite operation:
Leaf operation.
Leaf operation.