Improve HQP Title Scoring

chrome/browser/history/in_memory_url_index.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/history/in_memory_url_index.h"
 
 #include <algorithm>
 #include <functional>
 #include <iterator>
 #include <limits>
@@ skipping 730 matching lines @@
   match.can_inline =
       match.url_matches.size() == 1 && match.url_matches[0].offset == 0;
 
   // Get partial scores based on term matching. Note that the score for
   // each of the URL and title are adjusted by the fraction of the
   // terms appearing in each.
   int url_score = ScoreComponentForMatches(match.url_matches, url.size()) *
       match.url_matches.size() / terms.size();
   int title_score =
       ScoreComponentForMatches(match.title_matches, title.size()) *
-      static_cast<int>(match.title_matches.size()) /
-      static_cast<int>(terms.size());
+      match.title_matches.size() / terms.size();
   // Arbitrarily pick the best.
   // TODO(mrossetti): It might make sense that a term which appears in both the
   // URL and the Title should boost the score a bit.
   int term_score = std::max(url_score, title_score);
   if (term_score == 0)
     return match;
 
   // Determine scoring factors for the recency of visit, visit count and typed
   // count attributes of the URLRow.
   const int kDaysAgoLevel[] = { 0, 10, 20, 30 };
@@ skipping 58 matching lines @@
   const int kStartMaxValue = 250;
   int start_value = (kMaxSignificantStart -
       std::min(kMaxSignificantStart, matches[0].offset)) * kStartMaxValue /
       kMaxSignificantStart;
 
   // Score component for how much of the matched string the input terms cover.
   // kCompleteMaxValue points times the fraction of the URL/page title string
   // that was matched.
   size_t term_length_total = std::accumulate(matches.begin(), matches.end(),
                                              0, AccumulateMatchLength);
+  const size_t kMaxSignificantLength = 50;
+  size_t max_significant_length =
+      std::min(max_length, std::max(term_length_total, kMaxSignificantLength));
   const int kCompleteMaxValue = 500;
-  int complete_value = term_length_total * kCompleteMaxValue / max_length;
+  int complete_value =
+      term_length_total * kCompleteMaxValue / max_significant_length;
 
   int raw_score = order_value + start_value + complete_value;
   const int kTermScoreLevel[] = { 1000, 650, 500, 200 };
 
   // Scale the sum of the three components above into a single score component
   // on the same scale as that used in ScoredMatchForURL().
   return ScoreForValue(raw_score, kTermScoreLevel);
 }
 
 InMemoryURLIndex::AddHistoryMatch::AddHistoryMatch(
@@ skipping 237 matching lines @@
     if (iter->has_title()) {
       string16 title(UTF8ToUTF16(iter->title()));
       url_row.set_title(title);
     }
     history_info_map_[history_id] = url_row;
   }
   return true;
 }
 
 }  // namespace history