Merge branch 'SmartRangeFilterFix' into 'master'

Smart range filter fix

See merge request OpenMesh/OpenMesh!261

src/OpenMesh/Core/Mesh/SmartRange.hh

@@ -408,6 +408,20 @@ struct SmartRangeT
     return FilteredSmartRangeT<SmartRange, Handle, typename std::decay<Functor>::type>(f, b, e);
   }
 
+  /** @brief Only iterate over a subset of elements
+   *
+   * Returns a smart range which skips all elements that do not satisfy functor \p f
+   *
+   * @param f Functor that needs to be evaluated to true if the element should not be skipped.
+   */
+  template <typename Functor>
+  auto filtered(Functor& f) -> FilteredSmartRangeT<SmartRange, Handle, const typename std::decay<Functor>::type&>
+  {
+    auto range = static_cast<const RangeT*>(this);
+    auto b = (*range).begin();
+    auto e = (*range).end();
+    return FilteredSmartRangeT<SmartRange, Handle, const typename std::decay<Functor>::type&>(f, b, e);
+  }
 };
 
 
@@ -423,7 +437,7 @@ struct FilteredSmartRangeT : public SmartRangeT<FilteredSmartRangeT<RangeT, Hand
 
     FilteredIterator(Functor f, BaseIterator it, BaseIterator end): BaseIterator(it), f_(f), end_(end)
     {
-      if (!f_(*(*this))) // if start is not valid go to first valid one
+      if (!BaseIterator::operator==(end_) && !f_(*(*this))) // if start is not valid go to first valid one
         operator++();
     }
 

src/Unittests/unittests_smart_ranges.cc

@@ -301,6 +301,7 @@ TEST_F(OpenMeshSmartRanges, ForEach)
 TEST_F(OpenMeshSmartRanges, Filtered)
 {
   using VH = OpenMesh::VertexHandle;
+  using FH = OpenMesh::FaceHandle;
 
   auto is_even            = [](VH vh) { return vh.idx() % 2 == 0; };
   auto is_odd             = [](VH vh) { return vh.idx() % 2 == 1; };
@@ -342,6 +343,47 @@ TEST_F(OpenMeshSmartRanges, Filtered)
   EXPECT_EQ(vertices.size(), mesh_.n_vertices()) << " number of visited vertices not correct";
   EXPECT_TRUE(mesh_.vertices().all_of([&](VH vh) { return !to_be_processed(vh); })) << "did not visit all vertices";
 
+  {
+    OpenMesh::FProp<bool> to_be_visited(true, mesh_);
+    int visited_faces_in_main_loop = 0;
+    int visited_faces_in_sub_loop = 0;
+    for (auto fh : mesh_.faces().filtered(to_be_visited))
+    {
+      to_be_visited(fh) = false;
+      ++visited_faces_in_main_loop;
+      for (auto neighbor : fh.faces().filtered(to_be_visited))
+      {
+        to_be_visited(neighbor) = false;
+        ++visited_faces_in_sub_loop;
+      }
+    }
+
+    EXPECT_LT(visited_faces_in_main_loop, mesh_.n_faces()) << "Visted more faces than expected";
+    EXPECT_TRUE(mesh_.faces().all_of([&](FH fh) { return !to_be_visited(fh); })) << "did not visit all faces";
+    EXPECT_EQ(visited_faces_in_main_loop + visited_faces_in_sub_loop, mesh_.n_faces()) << "Did not visited all faces exactly once";
+  }
+
+  {
+    OpenMesh::FProp<bool> to_be_visited(true, mesh_);
+    const auto& to_be_visited_const_ref = to_be_visited;
+    int visited_faces_in_main_loop = 0;
+    int visited_faces_in_sub_loop = 0;
+    for (auto fh : mesh_.faces().filtered(to_be_visited_const_ref))
+    {
+      to_be_visited(fh) = false;
+      ++visited_faces_in_main_loop;
+      for (auto neighbor : fh.faces().filtered(to_be_visited_const_ref))
+      {
+        to_be_visited(neighbor) = false;
+        ++visited_faces_in_sub_loop;
+      }
+    }
+
+    EXPECT_LT(visited_faces_in_main_loop, mesh_.n_faces()) << "Visted more faces than expected";
+    EXPECT_TRUE(mesh_.faces().all_of([&](FH fh) { return !to_be_visited(fh); })) << "did not visit all faces";
+    EXPECT_EQ(visited_faces_in_main_loop + visited_faces_in_sub_loop, mesh_.n_faces()) << "Did not visited all faces exactly once";
+  }
+
 }