Repo created

libs/search/features_layer_path_finder.hpp

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+#pragma once
+
+#include "search/cancel_exception.hpp"
+#include "search/features_layer.hpp"
+#include "search/intersection_result.hpp"
+
+#ifdef DEBUG
+#include "base/logging.hpp"
+#include "base/timer.hpp"
+#endif  // DEBUG
+
+#include <utility>
+#include <vector>
+
+class FeaturesVector;
+class MwmValue;
+
+namespace base
+{
+class Cancellable;
+}
+
+namespace search
+{
+class FeaturesLayerMatcher;
+
+// This class is able to find all paths through a layered graph, with
+// vertices as features, and edges as pairs of vertices satisfying
+// belongs-to relation. For more details on belongs-to relation see
+// documentation for FeaturesLayerMatcher.
+//
+// In short, this class is able to find all features matching to a
+// given interpretation of a search query.
+//
+// NOTE: this class *IS* thread-safe.
+class FeaturesLayerPathFinder
+{
+public:
+  // An internal mode. The modes should produce similar results
+  // and differ only in efficiency: a mode that is faster
+  // for a search query may be slower for another.
+  // Modes other than MODE_AUTO should be used only by the testing code.
+  enum Mode
+  {
+    MODE_AUTO,
+    MODE_TOP_DOWN,
+    MODE_BOTTOM_UP
+  };
+
+  FeaturesLayerPathFinder(base::Cancellable const & cancellable) : m_cancellable(cancellable) {}
+
+  template <typename TFn>
+  void ForEachReachableVertex(FeaturesLayerMatcher & matcher, std::vector<FeaturesLayer const *> const & layers,
+                              TFn && fn)
+  {
+    if (layers.empty())
+      return;
+
+// TODO (@y): remove following code as soon as
+// FindReachableVertices() will work fast for most cases
+// (significantly less than 1 second).
+#ifdef DEBUG
+    for (auto const * layer : layers)
+      LOG(LDEBUG, (DebugPrint(*layer)));
+
+    size_t count = 0;
+    base::Timer timer;
+#endif  // DEBUG
+
+    FindReachableVertices(matcher, layers, [&](IntersectionResult const & r)
+    {
+      fn(r);
+#ifdef DEBUG
+      ++count;
+#endif  // DEBUG
+    });
+
+#ifdef DEBUG
+    LOG(LDEBUG, ("Found:", count, "elapsed:", timer.ElapsedSeconds(), "seconds"));
+#endif  // DEBUG
+  }
+
+  static void SetModeForTesting(Mode mode) { m_mode = mode; }
+
+private:
+  void BailIfCancelled() { ::search::BailIfCancelled(m_cancellable); }
+
+  template <class FnT>
+  void FindReachableVertices(FeaturesLayerMatcher & matcher, std::vector<FeaturesLayer const *> const & layers,
+                             FnT && fn);
+
+  // Tries to find all |reachable| features from the lowest layer in a
+  // high level -> low level pass.
+  template <class FnT>
+  void FindReachableVerticesTopDown(FeaturesLayerMatcher & matcher, std::vector<FeaturesLayer const *> const & layers,
+                                    FnT && fn);
+
+  // Tries to find all |reachable| features from the lowest layer in a
+  // low level -> high level pass.
+  template <class FnT>
+  void FindReachableVerticesBottomUp(FeaturesLayerMatcher & matcher, std::vector<FeaturesLayer const *> const & layers,
+                                     FnT && fn);
+
+  base::Cancellable const & m_cancellable;
+
+  static Mode m_mode;
+};
+}  // namespace search