访问者模式

来源：互联网发布：淘宝商城积分兑换编辑：程序博客网时间：2024/06/10 08:10
#include <iostream>#include <vector>#include <string>using namespace std;class Element;class Visitor{public:virtual void visitElementOne(Element* pobjElement) = 0;virtual void visitElementTwo(Element* pobjElement) = 0;};class Element{public:Element(const string& strName) : m_strName(strName) {}virtual void accept(Visitor* pobjVisitor) = 0;void setName(const string& strName) { m_strName = strName; }const string& getName() { return m_strName; }protected:string m_strName = "";};class VisitorOne : public Visitor{public:virtual void visitElementOne(Element* pobjElement) override{cout << pobjElement->getName() << " visitor one visits one" << endl;}virtual void visitElementTwo(Element* pobjElement) override{cout << pobjElement->getName() << " visitor one visits two" << endl;}};class VisitorTwo : public Visitor{public:virtual void visitElementOne(Element* pobjElement) override{cout << pobjElement->getName() << " visitor two visits one" << endl;}virtual void visitElementTwo(Element* pobjElement) override{cout << pobjElement->getName() << " visitor two visits two" << endl;}};class ElementOne : public Element{public:ElementOne(const string& strName) : Element(strName) {}virtual void accept(Visitor* pobjVisitor) override{pobjVisitor->visitElementOne(this);}};class ElementTwo : public Element{public:ElementTwo(const string& strName) : Element(strName) {}virtual void accept(Visitor* pobjVisitor) override{pobjVisitor->visitElementTwo(this);}};class ObjectStruct{public:void addElement(Element* pobjElement){m_vecElement.push_back(pobjElement);}void removeElement(Element* pobjElement){for (auto it = m_vecElement.begin(); it != m_vecElement.end(); ++it){if (*it == pobjElement){m_vecElement.erase(it);break;}}}void accept(Visitor* pobjVisitor){for (auto& it : m_vecElement){if (it){it->accept(pobjVisitor);}}}private:vector<Element*> m_vecElement;};int main(){ObjectStruct objObjectStruct;objObjectStruct.addElement(new ElementOne("彳亍"));objObjectStruct.addElement(new ElementTwo("行"));Visitor* pobjVisitorOne = new VisitorOne();Visitor* pobjVisitorTwo = new VisitorTwo();objObjectStruct.accept(pobjVisitorOne);objObjectStruct.accept(pobjVisitorTwo);return 0;}
总结：把处理从数据结构中分离，需要数据结构相对稳定
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