[search] Used linear model for rank calculation.

2 files changed, 54 insertions, 5 deletions

diff --git a/base/base_tests/stl_helpers_test.cpp b/base/base_tests/stl_helpers_test.cpp
index 00b59ab302..7d23bdd3d2 100644
--- a/base/base_tests/stl_helpers_test.cpp
+++ b/base/base_tests/stl_helpers_test.cpp
@@ -6,7 +6,20 @@
 #include "std/utility.hpp"
 #include "std/vector.hpp"
 
-UNIT_TEST(CompareBy_Smoke)
+namespace
+{
+class Int
+{
+public:
+  explicit Int(int v) : m_v(v) {}
+
+  inline int Get() const { return m_v; }
+
+private:
+  int m_v;
+};
+
+UNIT_TEST(CompareBy_Field)
 {
   vector<pair<int, int>> v = {{2, 2}, {0, 4}, {3, 1}, {4, 0}, {1, 3}};
   sort(v.begin(), v.end(), my::CompareBy(&pair<int, int>::first));
@@ -21,3 +34,15 @@ UNIT_TEST(CompareBy_Smoke)
   for (size_t i = 0; i < pv.size(); ++i)
     TEST_EQUAL(i, pv[i]->second, ());
 }
+
+UNIT_TEST(CompareBy_Method)
+{
+  vector<Int> v;
+  for (int i = 9; i >= 0; --i)
+    v.emplace_back(i);
+
+  sort(v.begin(), v.end(), my::CompareBy(&Int::Get));
+  for (size_t i = 0; i < v.size(); ++i)
+    TEST_EQUAL(v[i].Get(), static_cast<int>(i), ());
+}
+}  // namespace
diff --git a/base/stl_helpers.hpp b/base/stl_helpers.hpp
index 7dcc4f5beb..916989a040 100644
--- a/base/stl_helpers.hpp
+++ b/base/stl_helpers.hpp
@@ -7,8 +7,11 @@ namespace my
 {
 namespace impl
 {
-template <typename T, typename C>
-struct Comparer
+template <bool isField, typename T, typename C>
+struct Comparer;
+
+template<typename T, typename C>
+struct Comparer<true, T, C>
 {
   Comparer(T(C::*p)) : p_(p) {}
 
@@ -21,6 +24,21 @@ struct Comparer
 
   T(C::*p_);
 };
+
+template<typename T, typename C>
+struct Comparer<false, T, C>
+{
+  Comparer(T (C::*p)() const) : p_(p) {}
+
+  inline bool operator()(C const & lhs, C const & rhs) const { return (lhs.*p_)() < (rhs.*p_)(); }
+
+  inline bool operator()(C const * const lhs, C const * const rhs) const
+  {
+    return (lhs->*p_)() < (rhs->*p_)();
+  }
+
+  T(C::*p_)() const;
+};
 }  // namespace impl
 
 // Sorts and removes duplicate entries from |v|.
@@ -36,8 +54,14 @@ void SortUnique(std::vector<T> & v)
 // create comparer that is able to compare pairs of ints by second
 // component, it's enough to call CompareBy(&pair<int, int>::second).
 template <typename T, typename C>
-impl::Comparer<T, C> CompareBy(T(C::*p))
+impl::Comparer<true, T, C> CompareBy(T(C::*p))
+{
+  return impl::Comparer<true, T, C>(p);
+}
+
+template <typename T, typename C>
+impl::Comparer<false, T, C> CompareBy(T (C::*p)() const)
 {
-  return impl::Comparer<T, C>(p);
+  return impl::Comparer<false, T, C>(p);
 }
 }  // namespace my