Function slice_utf16

codegraph-kernel/src/textutil.rs:111–128

JS `String.prototype.slice(0, n)` in UTF-16 units, without splitting a surrogate pair (when the cut would split one, we stop one code unit short — a lone surrogate isn't representable in Rust and never round-trips through SQLite anyway). Returns (sliced, was_truncated_at_or_beyond_n).

(s: &str, n: usize)

/// a lone surrogate isn't representable in Rust and never round-trips through
/// SQLite anyway). Returns (sliced, was_truncated_at_or_beyond_n).
pub fn slice_utf16(s: &str, n: usize) -> (String, bool) {
    let mut used = 0usize;
    let mut out = String::new();
    for c in s.chars() {
        let w = c.len_utf16();
        if used + w > n {
            return (out, true);
        }
        used += w;
        out.push(c);
        if used == n {
            // Exactly at the limit: truncated iff any source remains.
            let truncated = out.len() < s.len();
            return (out, truncated);
        }
    }
    (out, false)
}

/// objectKeyName (tree-sitter.ts): strip ONE leading and ONE trailing quote
/// character (`'`, `"`, or backtick).