stack.cpp

////////////////////////////////////////////////////////////////////////////////
// Module Name:  int_stack.h/cpp
// Authors:      Sergey Shershakov
// Version:      0.2.0
// Date:         23.01.2017
//
// This is a part of the course "Algorithms and Data Structures"
// provided by  the School of Software Engineering of the Faculty
// of Computer Science at the Higher School of Economics.
////////////////////////////////////////////////////////////////////////////////


#include "int_stack.h"
#include <stdexcept>

// TODO: add necessary headers here
// #include <...

namespace xi {

    /** Declares a stack of integers.
     */
     //----<Main ADT interface>----

    IntStack::IntStack(size_t sz)
    {
        _stack = new int[sz];
        _ssize = sz;
        _head = 0;
    }

    IntStack::~IntStack()
    {
        delete[] _stack;
        _ssize = 0;
        _head = 0;
    }

    /** Pushes a given element onto the stack.
      *
      *  If no more elements can be placed onto the stack due to its overflow an std::logic_error is thrown.
      */
    void IntStack::push(int el)
    {
        if (isFull())
            throw std::logic_error("The stack is full.");
        _stack[_head++] = el;
    }

    /** Pops an element from the stack and returns its value.
     *
     *  If no elements stored in the stack, a std::logic_error is thrown.
     */
    int IntStack::pop()
    {
        if (isEmpty())
            throw std::logic_error("The stack is empty.");
        return _stack[--_head];
    }

    /** Looks up an element from the top of the stack and returns its value.
     *
     *  If no elements stored in the stack, a std::logic_error is thrown.
     */
    int IntStack::top()
    {
        if (isEmpty())
            throw std::logic_error("The stack is empty.");
        return _stack[_head - 1];
    }

    /** Clears the stack and makes it empty.
     *
     *  Often named as makeEmpty or similar
     */
    void IntStack::clear()
    {
        delete[] _stack;
        _stack = new int[_ssize];
        _head = 0;
    }

    // Non classic ADT helper methods

    /** Returns true if the stack is empty, false otherwise */
    bool IntStack::isEmpty() const
    {
        if (_head == 0)
            return true;
        return false;
    }

    /** Returns true if the stack is full, false otherwise */
    bool IntStack::isFull() const
    {
        if (_head == _ssize)
            return true;
        return false;
    }

} // namespace xi