Function line_span::find_prev_line_start [−][src]
pub fn find_prev_line_start(text: &str, index: usize) -> Option<usize>
Expand description
Find the start (byte index) of the previous line, the line before the one which index
is within.
Returns None
if there is no previous line.
See also
find_prev_line_range
to find both start and end of the previous line.find_prev_line_end
to find the end of the previous line.find_line_start
to find the start of the current line.find_next_line_start
to find the start of the next line.
Panics
Panics if index
is out of bounds.
Example
let text = "foo\nbar\nbaz";
let i = 9; // 'a'
let start = line_span::find_prev_line_start(text, i).unwrap();
assert_eq!(start, 4);
assert_eq!(&text[start..], "bar\nbaz");