Function line_span::find_prev_line_range

pub fn find_prev_line_range(text: &str, index: usize) -> Option<Range<usize>>

Find the start and end (byte index) of the previous line, the line before the one which index is within.

Note the end is the last character, excluding \n and \r\n.

Returns None if there is no previous line.

See also

• find_prev_line_start to find only the start of the previous line.
• find_prev_line_end to find only the end of the previous line.
• find_line_range to find the start and end of the current line.
• find_next_line_range to find the start and end of the next line.

Panics

Panics if index is out of bounds.

Example

let text = "foo\nbar\nbaz";
let i = 9; // 'a'

let range = line_span::find_prev_line_range(text, i).unwrap();
assert_eq!(range, 4..7);

let line = &text[range];
assert_eq!(line, "bar");