AutoDiff Code Generation - CMake Integration

This patch integrates the code generation module into the build
system. All depenendcies are tracked through CMake targets.
Modifying the cost functor will automatically trigger code
re-generation.

All this functionality is defined in the CMake function
ceres_generate_cost_function_implementation_for_functor
in CeresCodeGeneration.cmake. A hello world usage example
is included in examples/CMakeLists.txt.

Change-Id: I23b8b6698d1ea51cf3d788a47afcf39f8c5ce327

examples/CMakeLists.txt

@@ -73,8 +73,15 @@ add_executable(simple_bundle_adjuster simple_bundle_adjuster.cc)
 target_link_libraries(simple_bundle_adjuster ceres)
 
 if(CODE_GENERATION)
-  add_executable(autodiff_codegen autodiff_codegen.cc)
-  target_link_libraries(autodiff_codegen ceres)
+  include(CeresCodeGeneration)
+  ceres_generate_cost_function_implementation_for_functor(
+    NAME HelloWorldCostFunction
+    INPUT_FILE helloworld_cost_function.h
+    OUTPUT_DIRECTORY examples
+    NAMESPACE helloworld
+    )
+  add_executable(helloworld_codegen helloworld_codegen.cc )
+  target_link_libraries(helloworld_codegen ceres HelloWorldCostFunction)
 endif(CODE_GENERATION)
 
 if (GFLAGS)

examples/helloworld_codegen.cc

@@ -0,0 +1,65 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2019 Google Inc. All rights reserved.
+// http://code.google.com/p/ceres-solver/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+//   this list of conditions and the following disclaimer.
+// * Redistributions in binary form must reproduce the above copyright notice,
+//   this list of conditions and the following disclaimer in the documentation
+//   and/or other materials provided with the distribution.
+// * Neither the name of Google Inc. nor the names of its contributors may be
+//   used to endorse or promote products derived from this software without
+//   specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+// POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: darius.rueckert@fau.de (Darius Rueckert)
+//
+// A simple example showing how to generate code for a cost functor
+
+#include "ceres/ceres.h"
+#include "glog/logging.h"
+#include "helloworld_cost_function.h"
+
+using ceres::CostFunction;
+using ceres::Problem;
+using ceres::Solve;
+using ceres::Solver;
+
+int main(int argc, char** argv) {
+  google::InitGoogleLogging(argv[0]);
+
+  // The variable to solve for with its initial value. It will be
+  // mutated in place by the solver.
+  double x = 0.5;
+  const double initial_x = x;
+
+  Problem problem;
+
+  const double kTargetValue = 10.0;
+  CostFunction* cost_function =
+      new helloworld::HelloWorldCostFunction(kTargetValue);
+  problem.AddResidualBlock(cost_function, NULL, &x);
+
+  Solver::Options options;
+  options.minimizer_progress_to_stdout = true;
+  Solver::Summary summary;
+  Solve(options, &problem, &summary);
+
+  std::cout << summary.BriefReport() << "\n";
+  std::cout << "x : " << initial_x << " -> " << x << "\n";
+  return 0;
+}

examples/helloworld_cost_function.h

@@ -28,28 +28,29 @@
 //
 // Author: darius.rueckert@fau.de (Darius Rueckert)
 //
-// A simple example showing how to generate code for a cost functor
-//
-// We recommend to use the CMake integration instead of using
-// GenerateCodeForFunctor directly.
-//
-#include "ceres/codegen/autodiff.h"
+#include "ceres/codegen/codegen_cost_function.h"
+
+namespace helloworld {
+
+struct HelloWorldCostFunction : public ceres::CodegenCostFunction<1, 1> {
+  // We need a default constructor, because code is generated for the cost
+  // functor and not a specific instantiation of it.
+  HelloWorldCostFunction() = default;
+  explicit HelloWorldCostFunction(double target_value)
+      : target_value_(target_value) {}
 
-struct SquareFunctor {
   template <typename T>
   bool operator()(const T* x, T* residual) const {
-    residual[0] = x[0] * x[0];
-    isfinite(x[0]);
+    residual[0] = CERES_LOCAL_VARIABLE(T, target_value_) - x[0];
     return true;
   }
+
+// The include file name is automatically generated as
+// "<output_dir>/<lower_case_class_name>.h"
+#include "examples/helloworldcostfunction.h"
+
+ private:
+  double target_value_;
 };
 
-int main(int argc, char** argv) {
-  std::vector<std::string> code =
-      ceres::GenerateCodeForFunctor<SquareFunctor, 1, 1>(
-          ceres::AutoDiffCodeGenOptions());
-  for (auto str : code) {
-    std::cout << str << std::endl;
-  }
-  return 0;
-}
+}  // namespace helloworld