Screen.h

#ifndef SCREEN_H
#define SCREEN_H

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

template <unsigned H, unsigned W> class Screen;
template <unsigned H, unsigned W> class Window_mgr;

template <unsigned H, unsigned W>
const Screen<H, W> & operator<<(std::ostream &os, const Screen<H, W> &);

template <unsigned H, unsigned W>
Screen<H, W> & operator>>(std::istream &is, Screen<H, W> &);

template <unsigned H, unsigned W>
class Screen
{
	friend void Window_mgr<H, W>::clear(std::size_t i);
	friend const Screen<H, W> & operator<< <H,W>(std::ostream &os, const Screen<H, W> &);
public:
	Screen() : contents(H * W, ' ') { }
	Screen(char c) : contents(H * W, c) { }
	
	char get() const { return contents[cursor]; }
	inline char get(unsigned l, unsigned r) const;
	
	inline Screen & move(unsigned l, unsigned r);
	inline Screen & set(char c);
	inline Screen & set(unsigned l, unsigned r, char c);
	inline Screen & set(const std::string & s);
	inline unsigned size() const;
	
private: 
	unsigned cursor = 0;
	std::string contents;
	
	void do_display(std::ostream &os) const { os << contents; }

};

template <unsigned H, unsigned W>
class Window_mgr
{
public:
	Window_mgr();
	inline void clear(std::size_t i);
	inline void showScreen(std::ostream & os, std::size_t i);
	inline std::size_t addScreen(const Screen<H, W> & s); 
	
private:	
	std::vector<Screen<H, W>> screens;
	
}; 

template <unsigned H, unsigned W>
const Screen<H, W> & operator<<(std::ostream &os, const Screen<H, W> & sc)
{
	sc.do_display(os);
	return sc;
}

template <unsigned H, unsigned W>
Screen<H, W> & operator>>(std::istream &is, Screen<H, W> & sc)
{
	std::string s;
	is >> s;
	sc.set(s);
	return sc; 
}

template <unsigned H, unsigned W>
Window_mgr<H, W>::Window_mgr() : screens{Screen<H, W>(' ')} { }

template <unsigned H, unsigned W>
inline void Window_mgr<H, W>::clear(std::size_t i)
{
	screens[i].contents = std::string(W * H, ' ');
}

template <unsigned H, unsigned W>
inline void Window_mgr<H, W>::showScreen(std::ostream & os, std::size_t i)
{
	os << screens[i];
}

template <unsigned H, unsigned W>
inline std::size_t Window_mgr<H, W>::addScreen(const Screen<H, W> & s)
{
	screens.push_back(s);
	return screens.size() - 1;
}

template <unsigned H, unsigned W>
inline char Screen<H, W>::get(unsigned l, unsigned r) const
{
	return contents[l * W + r];
}

template <unsigned H, unsigned W>
inline Screen<H, W> & Screen<H, W>::move(unsigned l, unsigned r)
{
	cursor = l * W + r;
	return *this;
}

template <unsigned H, unsigned W>
inline Screen<H, W> & Screen<H, W>::set(char c)
{
	contents[cursor] = c;
	return *this;
}

template <unsigned H, unsigned W>
inline Screen<H, W> & Screen<H, W>::set(unsigned l, unsigned r, char c)
{
	contents[l * W + r] = c;
	return *this;
}

template <unsigned H, unsigned W>
inline Screen<H, W> & Screen<H, W>::set(const std::string & s)
{
	contents = s;
	contents.resize(H * W, ' ');
	return *this;
}

template <unsigned H, unsigned W>
inline unsigned Screen<H, W>::size() const
{
	return W * H;
}

#endif