/*
 * lstack.cpp
 *
 *  Created on: 26.03.2015 г.
 *      Author: trifon
 */

#include <iostream>
using namespace std;
#include "lstack.h"

LinkedStack::LinkedStack() {
	top = NULL;
}

bool LinkedStack::empty() const {
	return top == NULL;
}

int LinkedStack::peek() const {
	if (empty()) {
		cout << "Грешка: опит за поглеждане в празен стек!\n";
		return 0;
	}

	return top->data;
}

void LinkedStack::push(int x) {
	StackElement* p = new StackElement;
	p->data = x;
	p->next = top;
	top = p;
}

int LinkedStack::pop() {
	if (empty()) {
		cout << "Грешка: опит за изключване от празен стек!\n";
		return 0;
	}
	// top != NULL

	StackElement* p = top;
	top = top->next;
	int x = p->data;
	delete p;
	return x;
}

LinkedStack::~LinkedStack() {
	/*
	 * while (!empty())
		pop();
	 */
	StackElement* toDelete;
	while (top != NULL) {
		toDelete = top;
		top = top->next;
		delete toDelete;
	}
	// top == NULL
}

LinkedStack::LinkedStack(LinkedStack const& ls)
	: top(NULL) {
	/*
	while (!ls.empty()) {
		push(ls.pop());
	}
	*/
	/*
	StackElement* toCopy = ls.top;
	while(toCopy != NULL) {
		push(toCopy->data);
		toCopy = toCopy->next;
	}
	*/
	StackElement* toCopy = ls.top;
	StackElement *copy, *lastCopied = NULL;
	while (toCopy != NULL) {
		copy = new StackElement;

		if (top == NULL)
			top = copy;

		copy->data = toCopy->data;

		if (lastCopied != NULL)
			lastCopied->next = copy;

		// преместване на указателите
		lastCopied = copy;
		toCopy = toCopy->next;
	}
	lastCopied->next = NULL;

}