Merge pull request #4095 from pleroy/Ranges

Remove discrete_trajectory_segment_range and use a range instead

physics/discrete_trajectory.hpp

@@ -3,6 +3,7 @@
 #include <iterator>
 #include <list>
 #include <memory>
+#include <ranges>
 #include <vector>
 
 #include "absl/container/btree_map.h"
@@ -15,7 +16,6 @@
 #include "physics/degrees_of_freedom.hpp"
 #include "physics/discrete_trajectory_iterator.hpp"
 #include "physics/discrete_trajectory_segment_iterator.hpp"
-#include "physics/discrete_trajectory_segment_range.hpp"
 #include "physics/discrete_trajectory_types.hpp"
 #include "physics/trajectory.hpp"
 #include "serialization/physics.pb.h"
@@ -33,7 +33,6 @@ using namespace principia::geometry::_space;
 using namespace principia::physics::_degrees_of_freedom;
 using namespace principia::physics::_discrete_trajectory_iterator;
 using namespace principia::physics::_discrete_trajectory_segment_iterator;
-using namespace principia::physics::_discrete_trajectory_segment_range;
 using namespace principia::physics::_discrete_trajectory_types;
 using namespace principia::physics::_trajectory;
 
@@ -48,9 +47,9 @@ class DiscreteTrajectory : public Trajectory<Frame> {
   using reverse_iterator = std::reverse_iterator<iterator>;
   using SegmentIterator = DiscreteTrajectorySegmentIterator<Frame>;
   using ReverseSegmentIterator = std::reverse_iterator<SegmentIterator>;
-  using SegmentRange = DiscreteTrajectorySegmentRange<SegmentIterator>;
-  using ReverseSegmentRange =
-      DiscreteTrajectorySegmentRange<ReverseSegmentIterator>;
+  using SegmentRange = std::ranges::subrange<SegmentIterator,
+                                             SegmentIterator,
+                                             std::ranges::subrange_kind::sized>;
 
   DiscreteTrajectory();
 
@@ -81,8 +80,7 @@ class DiscreteTrajectory : public Trajectory<Frame> {
   iterator upper_bound(Instant const& t) const;
 
   SegmentRange segments() const;
-  // TODO(phl): In C++20 this should be a reverse_view on segments.
-  ReverseSegmentRange rsegments() const;
+  std::ranges::reverse_view<SegmentRange> rsegments() const;
 
   SegmentIterator NewSegment();
 

physics/discrete_trajectory_body.hpp

@@ -142,19 +142,15 @@ DiscreteTrajectory<Frame>::upper_bound(Instant const& t) const {
 template<typename Frame>
 typename DiscreteTrajectory<Frame>::SegmentRange
 DiscreteTrajectory<Frame>::segments() const {
-  return SegmentRange(SegmentIterator(
-                          segments_.get(), segments_->begin()),
-                      SegmentIterator(
-                          segments_.get(), segments_->end()));
+  return SegmentRange(SegmentIterator(segments_.get(), segments_->begin()),
+                      SegmentIterator(segments_.get(), segments_->end()),
+                      segments_->size());
 }
 
 template<typename Frame>
-typename DiscreteTrajectory<Frame>::ReverseSegmentRange
+std::ranges::reverse_view<typename DiscreteTrajectory<Frame>::SegmentRange>
 DiscreteTrajectory<Frame>::rsegments() const {
-  return ReverseSegmentRange(std::reverse_iterator(SegmentIterator(
-                                 segments_.get(), segments_->end())),
-                             std::reverse_iterator(SegmentIterator(
-                                 segments_.get(), segments_->begin())));
+  return std::ranges::reverse_view(segments());
 }
 
 template<typename Frame>

physics/discrete_trajectory_iterator_body.hpp

@@ -41,7 +41,7 @@ DiscreteTrajectoryIterator<Frame>::operator--() {
   bool const point_is_at_end = is_at_end(point_);
   if (point_is_at_end) {
     // Move the iterator to the end of the last segment.
-    segment_ = std::prev(segment_.segments().end());
+    segment_ = std::prev(segment_.EndSegment());
     point_ = segment_->timeline_end();
     // Now proceed with the decrement.
   }

physics/discrete_trajectory_iterator_test.cpp

@@ -1,5 +1,6 @@
 #include "physics/discrete_trajectory_iterator.hpp"
 
+#include <iterator>
 #include <memory>
 
 #include "base/not_null.hpp"
@@ -33,6 +34,8 @@ class DiscreteTrajectoryIteratorTest : public ::testing::Test {
  protected:
   using World = Frame<struct WorldTag>;
   using Segments = _discrete_trajectory_types::Segments<World>;
+  static_assert(
+      std::bidirectional_iterator<DiscreteTrajectoryIterator<World>>);
 
   DiscreteTrajectoryIteratorTest()
       : segments_(MakeSegments(3)) {

physics/discrete_trajectory_segment_iterator.hpp

@@ -5,7 +5,6 @@
 #include "absl/container/btree_map.h"
 #include "base/macros.hpp"  // 🧙 For forward declarations.
 #include "base/not_null.hpp"
-#include "physics/discrete_trajectory_segment_range.hpp"
 #include "physics/discrete_trajectory_types.hpp"
 
 namespace principia {
@@ -39,7 +38,6 @@ namespace _discrete_trajectory_segment_iterator {
 namespace internal {
 
 using namespace principia::base::_not_null;
-using namespace principia::physics::_discrete_trajectory_segment_range;
 using namespace principia::physics::_discrete_trajectory_types;
 
 template<typename Frame>
@@ -72,8 +70,7 @@ class DiscreteTrajectorySegmentIterator {
 
   bool is_begin() const;
   bool is_end() const;
-  DiscreteTrajectorySegmentRange<DiscreteTrajectorySegmentIterator>
-  segments() const;
+  DiscreteTrajectorySegmentIterator EndSegment() const;
 
   typename Segments::iterator iterator() const;
 

physics/discrete_trajectory_segment_iterator_body.hpp

@@ -87,11 +87,10 @@ bool DiscreteTrajectorySegmentIterator<Frame>::is_end() const {
 }
 
 template<typename Frame>
-DiscreteTrajectorySegmentRange<DiscreteTrajectorySegmentIterator<Frame>>
-DiscreteTrajectorySegmentIterator<Frame>::segments() const {
+DiscreteTrajectorySegmentIterator<Frame>
+DiscreteTrajectorySegmentIterator<Frame>::EndSegment() const {
   DCHECK(segments_ != nullptr);
-  return {DiscreteTrajectorySegmentIterator(segments_, segments_->begin()),
-          DiscreteTrajectorySegmentIterator(segments_, segments_->end())};
+  return DiscreteTrajectorySegmentIterator(segments_, segments_->end());
 }
 
 template<typename Frame>

physics/discrete_trajectory_segment_iterator_test.cpp

@@ -1,5 +1,6 @@
 #include "physics/discrete_trajectory_segment_iterator.hpp"
 
+#include <iterator>
 #include <memory>
 
 #include "base/not_null.hpp"
@@ -27,6 +28,8 @@ class DiscreteTrajectorySegmentIteratorTest : public ::testing::Test {
  protected:
   using World = Frame<struct WorldTag>;
   using Segments = _discrete_trajectory_types::Segments<World>;
+  static_assert(
+      std::bidirectional_iterator<DiscreteTrajectorySegmentIterator<World>>);
 
   DiscreteTrajectorySegmentIteratorTest()
       : segments_(MakeSegments(3)) {

physics/physics.vcxproj

@@ -34,8 +34,6 @@
     <ClInclude Include="discrete_trajectory_segment_body.hpp" />
     <ClInclude Include="discrete_trajectory_segment_iterator.hpp" />
     <ClInclude Include="discrete_trajectory_segment_iterator_body.hpp" />
-    <ClInclude Include="discrete_trajectory_segment_range.hpp" />
-    <ClInclude Include="discrete_trajectory_segment_range_body.hpp" />
     <ClInclude Include="discrete_trajectory_types.hpp" />
     <ClInclude Include="discrete_trajectory_types_body.hpp" />
     <ClInclude Include="equipotential.hpp" />
@@ -106,7 +104,6 @@
     <ClCompile Include="clientele_test.cpp" />
     <ClCompile Include="discrete_trajectory_iterator_test.cpp" />
     <ClCompile Include="discrete_trajectory_segment_iterator_test.cpp" />
-    <ClCompile Include="discrete_trajectory_segment_range_test.cpp" />
     <ClCompile Include="discrete_trajectory_segment_test.cpp" />
     <ClCompile Include="discrete_trajectory_test.cpp" />
     <ClCompile Include="equipotential_test.cpp" />

physics/physics.vcxproj.filters

@@ -155,12 +155,6 @@
     <ClInclude Include="discrete_trajectory_types.hpp">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="discrete_trajectory_segment_range.hpp">
-      <Filter>Header Files</Filter>
-    </ClInclude>
-    <ClInclude Include="discrete_trajectory_segment_range_body.hpp">
-      <Filter>Source Files</Filter>
-    </ClInclude>
     <ClInclude Include="discrete_trajectory_segment_iterator_body.hpp">
       <Filter>Source Files</Filter>
     </ClInclude>
@@ -319,9 +313,6 @@
     <ClCompile Include="analytical_series_test.cpp">
       <Filter>Test Files</Filter>
     </ClCompile>
-    <ClCompile Include="discrete_trajectory_segment_range_test.cpp">
-      <Filter>Test Files</Filter>
-    </ClCompile>
     <ClCompile Include="discrete_trajectory_segment_iterator_test.cpp">
       <Filter>Test Files</Filter>
     </ClCompile>