[search] Make HotelsClassifier look at the query too (and not only at results).

The main reason is to avoid flickering of the filter button when
zoomed in to an area without hotels.

Author: mpimenov

search/emitter.hpp

@@ -6,7 +6,8 @@
 #include "base/logging.hpp"
 #include "base/timer.hpp"
 
-#include <utility>
+#include <string>
+#include <vector>
 
 namespace search
 {
@@ -31,6 +32,8 @@ class Emitter
 
   void AddBookmarkResult(bookmarks::Result const & result) { m_results.AddBookmarkResult(result); }
 
+  void PrecheckHotelQuery(std::vector<uint32_t> const & types) { m_results.PrecheckHotelQuery(types); }
+
   void Emit(bool force = false)
   {
     if (m_prevEmitSize == m_results.GetCount() && !force)

search/hotels_classifier.cpp

@@ -2,18 +2,14 @@
 
 #include "search/result.hpp"
 
-namespace search
-{
-// static
-bool HotelsClassifier::IsHotelResults(Results const & results)
-{
-  HotelsClassifier classifier;
-  for (auto const & r : results)
-    classifier.Add(r);
+#include "indexer/ftypes_matcher.hpp"
 
-  return classifier.IsHotelResults();
-}
+#include "base/logging.hpp"
+
+using namespace std;
 
+namespace search
+{
 void HotelsClassifier::Add(Result const & result)
 {
   if (result.m_details.m_isHotel)
@@ -22,14 +18,23 @@ void HotelsClassifier::Add(Result const & result)
   ++m_numResults;
 }
 
+void HotelsClassifier::PrecheckHotelQuery(vector<uint32_t> const & types)
+{
+  m_looksLikeHotelQuery = ftypes::IsHotelChecker::Instance()(types);
+}
+
 void HotelsClassifier::Clear()
 {
   m_numHotels = 0;
   m_numResults = 0;
+  m_looksLikeHotelQuery = false;
 }
 
 bool HotelsClassifier::IsHotelResults() const
 {
+  if (m_looksLikeHotelQuery)
+    return true;
+
   // Threshold used to activate hotels mode. Probably is too strict,
   // but we don't have statistics now.
   double const kThreshold = 0.75;

search/hotels_classifier.hpp

@@ -1,27 +1,37 @@
 #pragma once
 
 #include <cstdint>
+#include <vector>
 
 namespace search
 {
 class Result;
 class Results;
+
 // A binary classifier that can be used in conjunction with search
-// engine to decide whether the majority of results are hotels or not.
+// engine to decide whether the query is related to hotel search.
+//
+// Two ways we use to decide whether the user was searching for hotels:
+// 1. We may infer it from the query text.
+// 2. We may infer it from the query results: if the majority are hotels,
+//    probably the query was too.
 //
 // *NOTE* This class is NOT thread safe.
 class HotelsClassifier
 {
 public:
-  static bool IsHotelResults(Results const & results);
-
   void Add(Result const & result);
+
+  // The types are parsed from the original query in search::Processor.
+  void PrecheckHotelQuery(std::vector<uint32_t> const & types);
+
   void Clear();
 
   bool IsHotelResults() const;
 
 private:
   uint64_t m_numHotels = 0;
   uint64_t m_numResults = 0;
+  bool m_looksLikeHotelQuery = false;
 };
 }  // namespace search

search/processor.cpp

@@ -315,6 +315,9 @@ void Processor::SetQuery(string const & query)
   if (!m_isCategorialRequest)
     ForEachCategoryType(tokenSlice, [&](size_t, uint32_t t) { m_preferredTypes.push_back(t); });
 
+  if (m_isCategorialRequest)
+    m_emitter.PrecheckHotelQuery(m_preferredTypes);
+
   base::SortUnique(m_preferredTypes);
 }
 

search/result.hpp

@@ -218,6 +218,8 @@ class Results
 
   void AddBookmarkResult(bookmarks::Result const & result);
 
+  void PrecheckHotelQuery(std::vector<uint32_t> const & types) { m_hotelsClassif.PrecheckHotelQuery(types); }
+
   void Clear();
 
   Iter begin() { return m_results.begin(); }