Function offset_to_position

src/util.rs:322–344

Convert a byte offset in `content` to an LSP `Position` (line, character). This is the inverse of [`position_to_byte_offset`]. Characters are counted as UTF-16 code units per the LSP specification. If `offset` is past the end of `content`, the position at the end of the file is returned.

(content: &str, offset: usize)

/// If `offset` is past the end of `content`, the position at the end of
/// the file is returned.
pub(crate) fn offset_to_position(content: &str, offset: usize) -> Position {
    let mut line = 0u32;
    let mut col = 0u32;
    for (i, ch) in content.char_indices() {
        if i == offset {
            return Position {
                line,
                character: col,
            };
        }
        if ch == '\n' {
            line += 1;
            col = 0;
        } else {
            col += ch.len_utf16() as u32;
        }
    }
    // offset == content.len() (end of file)
    Position {
        line,
        character: col,
    }
}

/// Convert an LSP `Position` (line, character) to a byte offset in
/// `content`.