Define pcl::experimental::optional

Author: tin1254

filters/include/pcl/filters/experimental/transform_filter.h

@@ -12,9 +12,14 @@
 #include <pcl/common/point_tests.h>
 #include <pcl/filters/filter.h>
 
+#include <boost/optional.hpp> // std::optional for C++17
+
 namespace pcl {
 namespace experimental {
 
+template <typename PointT>
+using optional = boost::optional<PointT>;
+
 #define GET_POINT_TYPE(GridStructT) typename GridStructT::PointCloud::PointType
 
 /**
@@ -78,10 +83,9 @@ class TransformFilter : public Filter<PointT>, public GridStruct {
     // allocate enough space for points
     output.reserve(GridStruct::grid_.size());
     for (auto it = GridStruct::grid_.begin(); it != GridStruct::grid_.end(); ++it) {
-      const auto& res = GridStruct::filterGrid(it);
-      if (res) {
+      const experimental::optional<PointT> res = GridStruct::filterGrid(it);
+      if (res)
         output.push_back(res.value());
-      }
     }
   }
 };

filters/include/pcl/filters/experimental/voxel_grid.h

@@ -13,8 +13,6 @@
 #include <pcl/common/common.h>
 #include <pcl/filters/experimental/grid_filter_base.h>
 
-#include <boost/optional.hpp> // std::optional for C++17
-
 #include <unordered_map>
 
 namespace pcl {
@@ -345,7 +343,7 @@ class VoxelStructT {
     grid_[h].add(pt);
   }
 
-  inline boost::optional<PointT>
+  inline experimental::optional<PointT>
   filterGrid(const GridIterator grid_it)
   {
     const auto& voxel = grid_it->second;