Method search

app/src/AI/DocSearch.cpp:146–201

* @brief Returns up to k highest-BM25-scoring chunks. */

 * @brief Returns up to k highest-BM25-scoring chunks.
 */
QList<AI::DocSearch::Hit> AI::DocSearch::search(const QString& query, int k)
{
  if (!m_loaded || m_docs.isEmpty())
    return {};

  const auto qTokens = tokenize(query);
  if (qTokens.isEmpty())
    return {};

  QList<QPair<QString, double>> qIdf;
  qIdf.reserve(qTokens.size());
  for (const auto& t : qTokens) {
    const double w = m_idf.value(t, 0.0);
    if (w > 0.0)
      qIdf.append({t, w});
  }
  if (qIdf.isEmpty())
    return {};

  QList<QPair<int, double>> scored;
  scored.reserve(m_docs.size());
  for (int i = 0; i < m_docs.size(); ++i) {
    const auto& d   = m_docs[i];
    const double dl = d.length > 0 ? double(d.length) : 1.0;
    const double K  = m_k1 * (1.0 - m_b + m_b * dl / std::max(1.0, m_avgdl));

    double s = 0.0;
    for (const auto& [term, w] : qIdf) {
      const int tf = d.tf.value(term, 0);
      if (tf == 0)
        continue;

      s += w * (tf * (m_k1 + 1.0)) / (tf + K);
    }
    if (s > 0.0)
      scored.append({i, s});
  }

  std::sort(
    scored.begin(), scored.end(), [](const auto& a, const auto& b) { return a.second > b.second; });

  const int kMax = std::min<int>(k > 0 ? k : 5, scored.size());
  QList<Hit> out;
  out.reserve(kMax);
  for (int i = 0; i < kMax; ++i) {
    const auto& d = m_docs[scored[i].first];
    Hit h;
    h.id     = d.id;
    h.source = d.source;
    h.title  = d.title;
    h.body   = d.body;
    h.score  = scored[i].second;
    out.append(std::move(h));
  }
  return out;
}

/**