change to GTSAM_DT_MERGING and expose via CMake

cmake/HandleGeneralOptions.cmake

@@ -19,6 +19,7 @@ option(GTSAM_FORCE_STATIC_LIB               "Force gtsam to be a static library,
 option(GTSAM_USE_QUATERNIONS                "Enable/Disable using an internal Quaternion representation for rotations instead of rotation matrices. If enable, Rot3::EXPMAP is enforced by default." OFF)
 option(GTSAM_POSE3_EXPMAP                   "Enable/Disable using Pose3::EXPMAP as the default mode. If disabled, Pose3::FIRST_ORDER will be used." ON)
 option(GTSAM_ROT3_EXPMAP                    "Ignore if GTSAM_USE_QUATERNIONS is OFF (Rot3::EXPMAP by default). Otherwise, enable Rot3::EXPMAP, or if disabled, use Rot3::CAYLEY." ON)
+option(GTSAM_DT_MERGING                     "Enable/Disable merging of equal leaf nodes in DecisionTrees. This leads to significant speed up and memory savings." ON)
 option(GTSAM_ENABLE_CONSISTENCY_CHECKS      "Enable/Disable expensive consistency checks" OFF)
 option(GTSAM_ENABLE_MEMORY_SANITIZER        "Enable/Disable memory sanitizer" OFF)
 option(GTSAM_WITH_TBB                       "Use Intel Threaded Building Blocks (TBB) if available" ON)

gtsam/config.h.in

@@ -39,6 +39,9 @@
 	#cmakedefine GTSAM_ROT3_EXPMAP
 #endif
 
+// Whether to enable merging of equal leaf nodes in the Discrete Decision Tree.
+#cmakedefine GTSAM_DT_MERGING
+
 // Whether we are using TBB (if TBB was found and GTSAM_WITH_TBB is enabled in CMake)
 #cmakedefine GTSAM_USE_TBB
 

gtsam/discrete/DecisionTree-inl.h

@@ -212,7 +212,7 @@ namespace gtsam {
           f->push_back(Unique(branch));
         }
 
-#ifndef GTSAM_DT_NO_MERGING
+#ifdef GTSAM_DT_MERGING
         // If all the branches are the same, we can merge them into one
         if (f->allSame_) {
           assert(f->branches().size() > 0);

gtsam/discrete/tests/testAlgebraicDecisionTree.cpp

@@ -20,7 +20,6 @@
 #include <gtsam/discrete/DiscreteKey.h>  // make sure we have traits
 #include <gtsam/discrete/DiscreteValues.h>
 // headers first to make sure no missing headers
-//#define GTSAM_DT_NO_MERGING
 #include <gtsam/discrete/AlgebraicDecisionTree.h>
 #include <gtsam/discrete/DecisionTree-inl.h>  // for convert only
 #define DISABLE_TIMING

gtsam/discrete/tests/testDecisionTree.cpp

@@ -18,7 +18,6 @@
  */
 
 // #define DT_DEBUG_MEMORY
-// #define GTSAM_DT_NO_MERGING
 #define DISABLE_DOT
 #include <CppUnitLite/TestHarness.h>
 #include <gtsam/base/Testable.h>