Iterator Pattern

Iterator 패턴이란?
 - 집합체의 요소를 통일된 방법으로, 순서대로 지정하면서 처리하는 패턴

이름	설명
Aggregate	집합체를 나타내는 인터페이스
Iterator	하나씩 나열하면서 검색을 실행하는 인터페이스
Book	책을 나타내는 클래스
BookShelf	서가를 나타내는 클래스
BookShelfIterator	서가를 검색하는 클래스

iterator.h

#pragma once #include <iostream> using namespace std; template <class T> class Iterator { public: virtual bool hasNext() = 0; virtual T* next() = 0; }; template <class U> class Aggregate { public: virtual Iterator<U>* iterator() = 0; }; class Book { private: string name; public: Book() { } Book(string name) { this->name = name; } string getName() { return name; } }; class BookShelfIterator : public Iterator<Book> { private: Book** books; int max; int index; public: BookShelfIterator(Book** books, int max); bool hasNext(); Book* next(); }; class BookShelf : public Aggregate<Book> { private: Book** books; int max; int index; public: BookShelf(int maxsize); Book* getBookAt(int index) { return books[index]; } void appendBook(Book* book); int getLength() { return index; } Iterator<Book>* iterator() { return new BookShelfIterator(books, max); } };

iterator.cpp

#include "iterator.h" BookShelfIterator::BookShelfIterator(Book** books, int max) { this->books = books; this->max = max; this->index = 0; } bool BookShelfIterator::hasNext() { if(index < max) return true; return false; } Book* BookShelfIterator::next() { Book* book = books[index]; index++; return book; } BookShelf::BookShelf(int maxsize) { books = new Book*[maxsize]; max = maxsize; index = 0; } void BookShelf::appendBook(Book* book) { books[index] = book; index++; }

main.cpp

#include <iostream> #include <string> #include "iterator.h" using namespace std; int main() { BookShelf bookShelf(4); bookShelf.appendBook(new Book("Around the world in 80 Days")); bookShelf.appendBook(new Book("Bible")); bookShelf.appendBook(new Book("Cinderella")); bookShelf.appendBook(new Book("Daddy-Long-Legs")); Iterator<Book>* i = bookShelf.iterator(); while(i->hasNext()) { Book* book = (Book*)i->next(); cout<<(book->getName())<<endl; } return 0; }

main 함수의 while루프는 BookShelf의 구현에는 의존하지 않는다.!!!