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Source code

#include "forward_list.hpp"

#include <iostream>

template <typename T>
class Queue1 : private ForwardList<T> {
 public:
  T const& front() {
    return ForwardList<T>::front();
  }
  void push(T const& value) {
    ForwardList<T>::push_back(value);
  }
  void pop() {
    ForwardList<T>::remove(ForwardList<T>::find(nullptr, front()));
  }
  bool empty() {
    return ForwardList<T>::empty();
  }
};

template <typename T>
class Queue2 {
 public:
  T const& front() {
    return list_.front();
  }
  void push(T const& value) {
    list_.push_back(value);
  }
  void pop() {
    list_.remove(list_.find(nullptr, front()));
  }
  bool empty() {
    return list_.empty();
  }

private:
  ForwardList<T> list_;
};

template <typename Queue>
void consume_print(Queue& queue) {
  while (!queue.empty()) {
    std::cout << queue.front() << ' ';
    queue.pop();
  }
  std::cout << '\n';
}

// 显式实例化
template void consume_print<Queue1<char>>(Queue1<char>&);

// 特例化
template <>
void consume_print<Queue2<int>>(Queue2<int>& queue) {
  while (!queue.empty()) {
    std::cout << queue.front() << ' ';
    queue.pop();
  }
  std::cout << '\n';
}