From 29c1816a81b245a4f599db7a47caa5a80db0f5f7 Mon Sep 17 00:00:00 2001
From: Varun Agrawal <varagrawal@gmail.com>
Date: Fri, 9 Jun 2023 20:13:06 -0400
Subject: [PATCH] change to GTSAM_DT_MERGING and expose via CMake

---
 cmake/HandleGeneralOptions.cmake                   | 1 +
 gtsam/config.h.in                                  | 3 +++
 gtsam/discrete/DecisionTree-inl.h                  | 2 +-
 gtsam/discrete/tests/testAlgebraicDecisionTree.cpp | 1 -
 gtsam/discrete/tests/testDecisionTree.cpp          | 1 -
 5 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/cmake/HandleGeneralOptions.cmake b/cmake/HandleGeneralOptions.cmake
index 9ebb07331..c5fd9898c 100644
--- a/cmake/HandleGeneralOptions.cmake
+++ b/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)
diff --git a/gtsam/config.h.in b/gtsam/config.h.in
index 7f8936d1e..7c08d36bf 100644
--- a/gtsam/config.h.in
+++ b/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
 
diff --git a/gtsam/discrete/DecisionTree-inl.h b/gtsam/discrete/DecisionTree-inl.h
index 5c2b735a0..2f36007a9 100644
--- a/gtsam/discrete/DecisionTree-inl.h
+++ b/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);
diff --git a/gtsam/discrete/tests/testAlgebraicDecisionTree.cpp b/gtsam/discrete/tests/testAlgebraicDecisionTree.cpp
index d7e7a071c..55f5b61d7 100644
--- a/gtsam/discrete/tests/testAlgebraicDecisionTree.cpp
+++ b/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
diff --git a/gtsam/discrete/tests/testDecisionTree.cpp b/gtsam/discrete/tests/testDecisionTree.cpp
index 0559a782b..336945503 100644
--- a/gtsam/discrete/tests/testDecisionTree.cpp
+++ b/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>