Function makeLineAt

src/resolution/callback-synthesizer.ts:120–137

* Per-match line resolver over `src`, 1-based at `baseLine`. The inline * `src.slice(0, idx).split('\n').length` idiom is O(source-length) PER MATCH, * which goes quadratic on a match-dense source (a generated function full of * `.push(` calls re-scanned tens of thousands of times was most of the

(src: string, baseLine: number)

 * never produce a match — then answers each call with a binary search.
 */
function makeLineAt(src: string, baseLine: number): (idx: number) => number {
  let nl: number[] | null = null;
  return (idx: number) => {
    if (!nl) {
      nl = [];
      for (let i = src.indexOf('\n'); i !== -1; i = src.indexOf('\n', i + 1)) nl.push(i);
    }
    // Count newlines strictly before idx.
    let lo = 0;
    let hi = nl.length;
    while (lo < hi) {
      const mid = (lo + hi) >> 1;
      if (nl[mid]! < idx) lo = mid + 1;
      else hi = mid;
    }
    return baseLine + lo;
  };
}

function registrarField(src: string): string | null {
  const m = src.match(/this\.(\w+)\.(?:add|push|set)\(/);