class FileReader {

	usage lin{FileReader; Q1} where
		Q1 = lin{toString; Q1 + next; <Q1 + Q2>}
		Q2 = un{getCounter; Q2 + toString; Q2};
	
	File[Q3] file;
	string s;
	int counter;
	boolean isEof;
	
	void FileReader(File[Q3] f) {
		file = f;
		s = "";
		counter = 0;
		isEof = false;
	}
	
	sync void count() {
		counter = counter + 1;
	}
	
	int getCounter() {
		counter;
	}
	
	string toString() {
		count();
		s;
	}
	
	boolean next() {
		if(file.eof()) {
			isEof = true;
			file.close();
			false;
		} else {
			s = s ++ file.read();
			true;
		}
	}
	
}

class File {

	usage lin{File; Q1} where
		Q1 = lin{eof; <Q2 + Q3>}
		Q3 = lin{read; Q1}
		Q2 = lin{close; end};
	
	int linesInFile;
	int linesRead;
	boolean closed;
	boolean lineInBuffer;
	boolean eof;
	
	void File() {
		linesRead = 0;
		linesInFile = 5;
		closed = false;
		lineInBuffer = false;
		eof = false;
	}
	
	void close() {
		closed = true;
	}
	
	boolean eof() {
		lineInBuffer = !linesRead == linesInFile;
		eof = !lineInBuffer;
		eof;
	}
	
	string read() {
		linesRead = linesRead + 1;
		lineInBuffer = false;
		"reading line... \n";
	}
	
}