/*
 * The LineBreaker class takes a c++ string and splits it on spaces to provide
 * an array of pointers to char that is just what the classic Unix execv()
 * function desperately wants as an array of arguments.  A NULL is placed
 * after the data as required by execv().
 */

#pragma once
#ifndef _linebreaker2_h_
#define _linebreaker2_h_

#include <vector>
#include <memory>
#include <string>
#include <cstring>

using namespace std;

class LineBreaker2 {
public:
	LineBreaker2() { m_ptrs.push_back(nullptr); }

	/*
	 * Create all the object so that it contains the words in the line
	 * (as separated by blanks).
	 */
	LineBreaker2(string line): m_data(new char[line.length() + 1]) {
		strcpy(m_data.get(), line.c_str());
		fill();
	}

	/*
	 * Return an array of plain C pointers, ending with a NULL pointer,
	 * which represents all the words in the line.  This is what execv()
	 * wants for its second parameter.
	 */
	char **c_arr() { return m_ptrs.data(); }

	/*
	 * Returns the number of strings, excluding the terminator
	 */
	int size() { return m_ptrs.size() - 1; }

	/*
	 * Subscript.  Returns the plain c string at that subscript.
	 */
	char *operator[](int s) { return m_ptrs[s]; }

	/*
	 * Return the last string, or null if there are none.
	 */
	char *back() { return size() > 0 ? *(m_ptrs.end()-2) : nullptr; }

	/*
	 * Remove and return the last string, if any, otherwise return null.
	 */
	char *pop_back();
private:
	void fill();

	unique_ptr<char[]> m_data;
	vector<char *> m_ptrs;
};

#endif