Function find_balanced_range

core/src/llm/structured.rs:375–427

Byte range `[start, end)` of the first balanced `open..close` substring (quote-aware).

(text: &str, open: char, close: char)

/// Byte range `[start, end)` of the first balanced `open..close` substring (quote-aware).
fn find_balanced_range(text: &str, open: char, close: char) -> Option<(usize, usize)> {
    let bytes = text.as_bytes();
    let open_byte = open as u8;
    let close_byte = close as u8;

    // Find the first unquoted occurrence of `open`
    let mut in_string = false;
    let mut escape_next = false;
    let mut start = None;

    for (i, &b) in bytes.iter().enumerate() {
        if escape_next {
            escape_next = false;
            continue;
        }
        match b {
            b'\\' if in_string => escape_next = true,
            b'"' => in_string = !in_string,
            _ if in_string => {}
            _ if b == open_byte => {
                start = Some(i);
                break;
            }
            _ => {}
        }
    }

    let start = start?;
    let mut depth = 0i32;
    in_string = false;
    escape_next = false;

    for (i, &b) in bytes[start..].iter().enumerate() {
        if escape_next {
            escape_next = false;
            continue;
        }
        match b {
            b'\\' if in_string => escape_next = true,
            b'"' => in_string = !in_string,
            _ if in_string => {}
            _ if b == open_byte => depth += 1,
            _ if b == close_byte => {
                depth -= 1;
                if depth == 0 {
                    return Some((start, start + i + 1));
                }
            }
            _ => {}
        }
    }
    None
}

/// Every top-level balanced `open..close` substring, in document order.
///