line_position/2line_position(+Stream, -Count)
Obtains the total number of characters either input from or output to the current line of the open text stream Stream and unifies it with Count.
A valid open text stream.
The resulting line count of the stream.
A fresh line has a line position of 0, i.e. this predicate counts the length of the current line. Line count for a tty stream reflects the total line input from or output to the tty since the tty is opened to any stream.
The count is reset by set_stream_position/2.
Stream errors (see ref-iou-sfh-est).
byte_count/2, character_count/2, line_count/2,
stream_position/2,
set_stream_position/2,
ref-iou-sfh.