Repo created

libs/search/geometry_cache.hpp

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+#pragma once
+
+#include "search/cbv.hpp"
+
+#include "indexer/mwm_set.hpp"
+
+#include "geometry/rect2d.hpp"
+
+#include "base/assert.hpp"
+
+#include <algorithm>
+#include <cstdint>
+#include <deque>
+#include <map>
+#include <utility>
+
+namespace base
+{
+class Cancellable;
+}
+
+namespace search
+{
+class MwmContext;
+
+// This class represents a simple cache of features in rects for all mwms.
+//
+// *NOTE* This class is not thread-safe.
+class GeometryCache
+{
+public:
+  virtual ~GeometryCache() = default;
+
+  // Returns (hopefully, cached) list of features in a given
+  // rect. Note that return value may be invalidated on next calls to
+  // this method.
+  virtual CBV Get(MwmContext const & context, m2::RectD const & rect, int scale) = 0;
+
+  inline void Clear() { m_entries.clear(); }
+
+protected:
+  struct Entry
+  {
+    m2::RectD m_rect;
+    CBV m_cbv;
+    int m_scale = 0;
+  };
+
+  // |maxNumEntries| denotes the maximum number of rectangles that
+  // will be cached for each mwm individually.
+  GeometryCache(size_t maxNumEntries, base::Cancellable const & cancellable);
+
+  template <typename Pred>
+  std::pair<Entry &, bool> FindOrCreateEntry(MwmSet::MwmId const & id, Pred && pred)
+  {
+    auto & entries = m_entries[id];
+    auto it = std::find_if(entries.begin(), entries.end(), std::forward<Pred>(pred));
+    if (it != entries.end())
+    {
+      if (it != entries.begin())
+        iter_swap(entries.begin(), it);
+      return std::pair<Entry &, bool>(entries.front(), false);
+    }
+
+    entries.emplace_front();
+    if (entries.size() == m_maxNumEntries + 1)
+      entries.pop_back();
+
+    ASSERT_LESS_OR_EQUAL(entries.size(), m_maxNumEntries, ());
+    ASSERT(!entries.empty(), ());
+    return std::pair<Entry &, bool>(entries.front(), true);
+  }
+
+  void InitEntry(MwmContext const & context, m2::RectD const & rect, int scale, Entry & entry);
+
+  std::map<MwmSet::MwmId, std::deque<Entry>> m_entries;
+  size_t const m_maxNumEntries;
+  base::Cancellable const & m_cancellable;
+};
+
+class PivotRectsCache : public GeometryCache
+{
+public:
+  PivotRectsCache(size_t maxNumEntries, base::Cancellable const & cancellable, double maxRadiusMeters);
+
+  // GeometryCache overrides:
+  CBV Get(MwmContext const & context, m2::RectD const & rect, int scale) override;
+
+private:
+  double const m_maxRadiusMeters;
+};
+
+class LocalityRectsCache : public GeometryCache
+{
+public:
+  LocalityRectsCache(size_t maxNumEntries, base::Cancellable const & cancellable);
+
+  // GeometryCache overrides:
+  CBV Get(MwmContext const & context, m2::RectD const & rect, int scale) override;
+};
+}  // namespace search