The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
/* ************************************************************
* Queue.hpp
* - safer and more convenient queue class
* ************************************************************/
#ifndef QUEUE_HPP
#define QUEUE_HPP
#include <deque>
#include <exception>
template <typename T>
class Queue {
protected:
std::deque<T> c; // container for the elements
public:
// exception class for pop() and front() with empty queue
class ReadEmptyQueue : public std::exception {
public:
virtual const char* what() const throw() {
return "read empty queue";
}
};
// number of elements
typename std::deque<T>::size_type size() const {
return c.size();
}
// is queue empty?
bool empty() const {
return c.empty();
}
// insert element into the queue
void push (const T& elem) {
c.push_back(elem);
}
// remove next element from the queue and return its value
T pop () {
if (c.empty()) {
throw ReadEmptyQueue();
}
T elem(c.front());
c.pop_front();
return elem;
}
// return value of next element
T& front () {
if (c.empty()) {
throw ReadEmptyQueue();
}
return c.front();
}
};
#endif /* QUEUE_HPP */