Function offset_to_absolute

src/semantic_tokens.rs:808–830

Convert a byte offset and byte length to an absolute line/character position and build an [`AbsoluteToken`]. `length` is a **byte** count (as stored in [`SymbolSpan`]). This function converts it to a UTF-16 code-unit count as required by the LSP semantic token protocol. Returns `None` if the offset is beyond the content length.

(
    content: &str,
    start_offset: u32,
    byte_length: u32,
    token_type: u32,
    modifiers: u32,
)

///
/// Returns `None` if the offset is beyond the content length.
fn offset_to_absolute(
    content: &str,
    start_offset: u32,
    byte_length: u32,
    token_type: u32,
    modifiers: u32,
) -> Option<AbsoluteToken> {
    let start = start_offset as usize;
    let end = start + byte_length as usize;
    let text = content.get(start..end)?;
    let utf16_len: u32 = text.chars().map(|c| c.len_utf16() as u32).sum();
    if utf16_len == 0 {
        return None;
    }
    let pos = crate::util::offset_to_position(content, start);
    Some(AbsoluteToken {
        line: pos.line,
        start_char: pos.character,
        length: utf16_len,
        token_type,
        modifiers,
    })
}

/// Convert a list of absolute-positioned tokens into LSP delta-encoded
/// [`SemanticToken`] values.