DesignPattern/IteratorPattern/CppCode1 - lab.comp@wiki

#include <iostream>
using namespace std;
 
template <typename T>
struct iteratable {
    virtual ~iteratable() {}
 
    virtual const bool has_next() = 0;
    virtual void next() = 0;
    virtual const T get_value() = 0;
};
 
template <typename Iterator>
struct aggregatable {
    virtual ~aggregatable() {}
    virtual Iterator iterator_begin() = 0;
};
 
template <typename T, typename List>
class element_iterator : public iteratable<T> {
    const List &list_;
    size_t index_;
 
public :
    element_iterator(const List &list) : list_(list), index_(0) {}
 
    const bool has_next() {
        return (list_.get_last_num() > index_) ? true : false;
    }
 
    void next() { ++index_; }
 
    const T get_value() { return list_.get_value_at(index_); }
};
 
template <typename T>
class element_list : public aggregatable<element_iterator<T, element_list<T> > > {
    T *plist_;
    size_t last_;
 
public :
    typedef element_iterator<T, element_list<T> > iterator;
 
    element_list(const size_t count) : plist_(new T[count]), last_(0) {
    }
 
    ~element_list() {
        delete [] plist_;
    }
 
    void add(const T val) {
        plist_[last_++] = val;
    }
 
    const T get_value_at(const size_t index) const {
        return plist_[index];
    }
 
    const size_t get_last_num() const {
        return last_;
    }
 
    element_iterator<T, element_list<T>> iterator_begin() {
        return element_iterator<T, element_list<T> >(*this);
    }
};
 
int main() {
    element_list<int> list(5);
 
    for (int i = 0; i < 5; ++i) {
        list.add(i);
    }
 
    element_list<int>::iterator it = list.iterator_begin();
    for ( it; it.has_next(); it.next()) {
        cout << it.get_value() << endl;
    }
}