Screen.h

#ifndef SCREEN_H
#define SCREEN_H

#include<string>
#include<iostream>
#include<vector>

class Screen;
class Window_mgr;

class Window_mgr
{
public:
	
	using SIndex = std::vector<Screen>::size_type;
	
	Window_mgr(); 
	
	inline void clear(SIndex i);
	inline void showScreen(std::ostream & os, SIndex i);
	
private:
	
	std::vector<Screen> screens;
	
}; 

class Screen
{

	friend void Window_mgr::clear(SIndex i);
	
public:
	
	using pos = std::string::size_type;
	
	Screen() = default;
	Screen(pos l, pos r) : height(l), width(r), contents(l*r, ' ') { }
	Screen(pos l, pos r, char c) : height(l), width(r), contents(l*r, c) { }
	
	char get() const { return contents[cursor]; }
	inline char get(pos l, pos r) const;
	
	inline Screen & move(pos l, pos r);
	inline Screen & set(char c);
	inline Screen & set(pos l, pos r, char c);
	const Screen & display(std::ostream &os) const { do_display(os); return *this; }
	Screen & display(std::ostream &os) { do_display(os); return *this; }
	
private: 
	
	pos cursor = 0;
	pos height = 0, width = 0;
	std::string contents;
	
	void do_display(std::ostream &os) const { os << contents; }

};

Window_mgr::Window_mgr() : screens{Screen(24, 80, ' ')} { }

inline void Window_mgr::clear(SIndex i)
{
	screens[i].contents = std::string(screens[i].width * screens[i].height, ' ');
}

inline void Window_mgr::showScreen(std::ostream & os, SIndex i)
{
	screens[i].display(os);
}

inline char Screen::get(pos l, pos r) const
{
	return contents[l * width + r];
}

inline Screen & Screen::move(pos l, pos r)
{
	cursor = l * width + r;
	return *this;
}

inline Screen & Screen::set(char c)
{
	contents[cursor] = c;
	return *this;
}

inline Screen & Screen::set(pos l, pos r, char c)
{
	contents[l * width + r] = c;
	return *this;
}

#endif