rust-positions

index.rs

/// Returns `(line, column)`. Return is zero based
fn get_line_column_from_string_and_idx(end: u32, char_indices: &mut CharIndices) -> (u32, u32) {
    let (mut line, mut column) = (0, 0);
    for (_, chr) in char_indices.take_while(|(idx, _)| *idx < end.try_into().unwrap()) {
        if chr == '\n' {
            line += 1;
            column = 0;
        } else {
            column += chr.len_utf8() as u32;
        }
    }
    (line, column)
}

/// Converts line and column to index in string
///
/// Line and column are zero based
///
/// Inverse of [get_line_column_from_string_and_idx]
fn line_column_position_to_position(
    mut line: u32,
    column: u32,
    char_indices: &mut CharIndices,
    full_length: usize,
) -> usize {
    while line > 0 {
        // TODO unwrap
        if '\n' == char_indices.next().unwrap().1 {
            line -= 1;
        }
    }
    char_indices
        .next()
        .map(|(idx, _)| idx)
        .unwrap_or(full_length)
        + column as usize
}