Mega Code Archive
Use generic stack to store another container
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/* The following code example is taken from the book
* "C++ Templates - The Complete Guide"
* by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
*
* (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
#include <iostream>
#include <string>
#include <cstdlib>
#include <vector>
#include <deque>
#include <stdexcept>
template <typename T, typename CONT = std::deque<T> >
class Stack {
private:
CONT elems; // elements
public:
void push(T const&); // push element
void pop(); // pop element
T top() const; // return top element
bool empty() const { // return whether the stack is empty
return elems.empty();
}
// assign stack of elements of type T2
template <typename T2, typename CONT2>
Stack<T,CONT>& operator= (Stack<T2,CONT2> const&);
};
template <typename T, typename CONT>
template <typename T2, typename CONT2>
Stack<T,CONT>&
Stack<T,CONT>::operator= (Stack<T2,CONT2> const& op2)
{
if ((void*)this == (void*)&op2) { // assignment to itself?
return *this;
}
Stack<T2,CONT2> tmp(op2); // create a copy of the assigned stack
elems.clear(); // remove existing elements
while (!tmp.empty()) { // copy all elements
elems.push_front(tmp.top());
tmp.pop();
}
return *this;
}
template <typename T, typename CONT>
void Stack<T,CONT>::push (T const& elem)
{
elems.push_back(elem); // append copy of passed elem
}
template<typename T, typename CONT>
void Stack<T,CONT>::pop ()
{
if (elems.empty()) {
throw std::out_of_range("Stack<>::pop(): empty stack");
}
elems.pop_back(); // remove last element
}
template <typename T, typename CONT>
T Stack<T,CONT>::top () const
{
if (elems.empty()) {
throw std::out_of_range("Stack<>::top(): empty stack");
}
return elems.back(); // return copy of last element
}
int main()
{
try {
Stack<int> intStack; // stack of ints
Stack<float> floatStack; // stack of floats
// manipulate int stack
intStack.push(42);
intStack.push(7);
// manipulate float stack
floatStack.push(7.7);
// assign stacks of different type
floatStack = intStack;
// print float stack
std::cout << floatStack.top() << std::endl;
floatStack.pop();
std::cout << floatStack.top() << std::endl;
floatStack.pop();
std::cout << floatStack.top() << std::endl;
floatStack.pop();
}
catch (std::exception const& ex) {
std::cerr << "Exception: " << ex.what() << std::endl;
}
// stack for ints using a vector as an internal container
Stack<int,std::vector<int> > vStack;
//...
vStack.push(42);
vStack.push(7);
std::cout << vStack.top() << std::endl;
vStack.pop();
}
7
42
Exception: Stack::top(): empty stack
7
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