Restore booking flow.

Signed-off-by: Viktor Govako <viktor.govako@gmail.com>

generator/sponsored_scoring.cpp

@@ -0,0 +1,106 @@
+#include "generator/sponsored_scoring.hpp"
+
+#include "indexer/search_string_utils.hpp"
+
+#include "base/math.hpp"
+
+#include <algorithm>
+#include <vector>
+
+namespace
+{
+using WeightedBagOfWords = std::vector<std::pair<strings::UniString, double>>;
+
+std::vector<strings::UniString> StringToWords(std::string const & str)
+{
+  auto result = search::NormalizeAndTokenizeString(str);
+  std::sort(std::begin(result), std::end(result));
+  return result;
+}
+
+WeightedBagOfWords MakeWeightedBagOfWords(std::vector<strings::UniString> const & words)
+{
+  // TODO(mgsergio): Calculate tf-idsf score for every word.
+  auto constexpr kTfIdfScorePlaceholder = 1;
+
+  WeightedBagOfWords result;
+  for (size_t i = 0; i < words.size(); ++i)
+  {
+    result.emplace_back(words[i], kTfIdfScorePlaceholder);
+    while (i + 1 < words.size() && words[i] == words[i + 1])
+    {
+      result.back().second += kTfIdfScorePlaceholder;  // TODO(mgsergio): tf-idf score for result[i].frist;
+      ++i;
+    }
+  }
+  return result;
+}
+
+double WeightedBagsDotProduct(WeightedBagOfWords const & lhs, WeightedBagOfWords const & rhs)
+{
+  double result{};
+
+  auto lhsIt = begin(lhs);
+  auto rhsIt = begin(rhs);
+
+  while (lhsIt != end(lhs) && rhsIt != end(rhs))
+  {
+    if (lhsIt->first == rhsIt->first)
+    {
+      result += lhsIt->second * rhsIt->second;
+      ++lhsIt;
+      ++rhsIt;
+    }
+    else if (lhsIt->first < rhsIt->first)
+    {
+      ++lhsIt;
+    }
+    else
+    {
+      ++rhsIt;
+    }
+  }
+
+  return result;
+}
+
+double WeightedBagOfWordsCos(WeightedBagOfWords const & lhs, WeightedBagOfWords const & rhs)
+{
+  auto const product = WeightedBagsDotProduct(lhs, rhs);
+  auto const lhsLength = sqrt(WeightedBagsDotProduct(lhs, lhs));
+  auto const rhsLength = sqrt(WeightedBagsDotProduct(rhs, rhs));
+
+  // WeightedBagsDotProduct returns 0.0 if lhs.empty() || rhs.empty() or
+  // if every element of either lhs or rhs is 0.0.
+  if (product == 0.0)
+    return 0.0;
+
+  return product / (lhsLength * rhsLength);
+}
+}  // namespace
+
+namespace generator
+{
+namespace impl
+{
+double GetLinearNormDistanceScore(double distance, double const maxDistance)
+{
+  CHECK_NOT_EQUAL(maxDistance, 0.0, ("maxDistance cannot be 0."));
+  distance = base::Clamp(distance, 0.0, maxDistance);
+  return 1.0 - distance / maxDistance;
+}
+
+double GetNameSimilarityScore(std::string const & booking_name, std::string const & osm_name)
+{
+  auto const aws = MakeWeightedBagOfWords(StringToWords(booking_name));
+  auto const bws = MakeWeightedBagOfWords(StringToWords(osm_name));
+
+  if (aws.empty() && bws.empty())
+    return 1.0;
+  if (aws.empty() || bws.empty())
+    return 0.0;
+
+  return WeightedBagOfWordsCos(aws, bws);
+}
+}  // namespace impl
+}  // namespace generator