From 345d793028ff29990f387a5af6ee06e76e11c1f5 Mon Sep 17 00:00:00 2001
From: Aglargil <1252223935@qq.com>
Date: Mon, 10 Feb 2025 11:21:24 +0800
Subject: [PATCH 1/2] feat: add _onStart precondition for script execution

Add a new precondition type _onStart that allows executing scripts
before a node starts its tick. This provides symmetry with the
existing _post functionality.
---
 include/behaviortree_cpp/tree_node.h |  5 ++--
 src/tree_node.cpp                    | 35 +++++++++++++++-------------
 tests/gtest_preconditions.cpp        | 27 +++++++++++++++++++++
 3 files changed, 49 insertions(+), 18 deletions(-)

diff --git a/include/behaviortree_cpp/tree_node.h b/include/behaviortree_cpp/tree_node.h
index bd77c4c72..c89769413 100644
--- a/include/behaviortree_cpp/tree_node.h
+++ b/include/behaviortree_cpp/tree_node.h
@@ -50,11 +50,12 @@ enum class PreCond
   SUCCESS_IF,
   SKIP_IF,
   WHILE_TRUE,
+  ON_START,
   COUNT_
 };
 
-static const std::array<std::string, 4> PreCondNames = {  //
-  "_failureIf", "_successIf", "_skipIf", "_while"
+static const std::array<std::string, 5> PreCondNames = {  //
+  "_failureIf", "_successIf", "_skipIf", "_while", "_onStart"
 };
 
 enum class PostCond
diff --git a/src/tree_node.cpp b/src/tree_node.cpp
index 0d4dd66bd..a1dae2042 100644
--- a/src/tree_node.cpp
+++ b/src/tree_node.cpp
@@ -208,24 +208,27 @@ Expected<NodeStatus> TreeNode::checkPreConditions()
     // Some preconditions are applied only when the node state is IDLE or SKIPPED
     if(_p->status == NodeStatus::IDLE || _p->status == NodeStatus::SKIPPED)
     {
-      // what to do if the condition is true
-      if(parse_executor(env).cast<bool>())
+      auto execute_result = parse_executor(env);
+      if(preID == PreCond::ON_START)
       {
-        if(preID == PreCond::FAILURE_IF)
-        {
-          return NodeStatus::FAILURE;
-        }
-        else if(preID == PreCond::SUCCESS_IF)
-        {
-          return NodeStatus::SUCCESS;
-        }
-        else if(preID == PreCond::SKIP_IF)
-        {
-          return NodeStatus::SKIPPED;
-        }
+        return nonstd::make_unexpected("");  // no precondition
+      }
+      auto bool_result = execute_result.cast<bool>();
+      // what to do if the condition is true and the precondition is xx_IF
+      if(bool_result && preID == PreCond::FAILURE_IF)
+      {
+        return NodeStatus::FAILURE;
+      }
+      if(bool_result && preID == PreCond::SUCCESS_IF)
+      {
+        return NodeStatus::SUCCESS;
+      }
+      if(bool_result && preID == PreCond::SKIP_IF)
+      {
+        return NodeStatus::SKIPPED;
       }
-      // if the conditions is false
-      else if(preID == PreCond::WHILE_TRUE)
+      // if the condition is false and the precondition is WHILE_TRUE, skip the node
+      if(!bool_result && preID == PreCond::WHILE_TRUE)
       {
         return NodeStatus::SKIPPED;
       }
diff --git a/tests/gtest_preconditions.cpp b/tests/gtest_preconditions.cpp
index 7a3df89f7..6d86cf6ef 100644
--- a/tests/gtest_preconditions.cpp
+++ b/tests/gtest_preconditions.cpp
@@ -397,3 +397,30 @@ TEST(Preconditions, WhileCallsOnHalt)
   ASSERT_EQ(status, BT::NodeStatus::SKIPPED);
   ASSERT_EQ(tree.rootBlackboard()->get<int>("B"), 69);
 }
+
+TEST(Preconditions, OnStart)
+{
+  BehaviorTreeFactory factory;
+  std::array<int, 3> counters;
+  RegisterTestTick(factory, "Test", counters);
+  static constexpr auto xml_text = R"(
+  <root BTCPP_format="4">
+    <BehaviorTree ID="Main">
+      <Sequence>
+        <AlwaysSuccess _onStart="B:=69"/>
+        <TestA/>
+        <TestB _successIf="B==69"/>
+        <TestC _onStart="C:=70" _post="B=70"/>
+      </Sequence>
+    </BehaviorTree>
+  </root>
+  )";
+  auto tree = factory.createTreeFromText(xml_text);
+  const auto status = tree.tickWhileRunning();
+  ASSERT_EQ(status, NodeStatus::SUCCESS);
+  ASSERT_EQ(tree.rootBlackboard()->get<int>("B"), 70);
+  ASSERT_EQ(tree.rootBlackboard()->get<int>("C"), 70);
+  ASSERT_EQ(counters[0], 1);
+  ASSERT_EQ(counters[1], 0);
+  ASSERT_EQ(counters[2], 1);
+}

From d8ca1f1b055aaf50d4c95b26f204e787d77b6b71 Mon Sep 17 00:00:00 2001
From: Aglargil <1252223935@qq.com>
Date: Mon, 10 Feb 2025 11:47:22 +0800
Subject: [PATCH 2/2] fix: covert_impl checkTruncation

---
 include/behaviortree_cpp/utils/convert_impl.hpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/behaviortree_cpp/utils/convert_impl.hpp b/include/behaviortree_cpp/utils/convert_impl.hpp
index dffe17c98..e62ec2a0e 100644
--- a/include/behaviortree_cpp/utils/convert_impl.hpp
+++ b/include/behaviortree_cpp/utils/convert_impl.hpp
@@ -101,7 +101,7 @@ inline void checkTruncation(const From& from)
     }
   }
   // Handle floating point to integer
-  if constexpr(std::is_floating_point_v<From> && std::is_integral_v<To>)
+  else if constexpr(std::is_floating_point_v<From> && std::is_integral_v<To>)
   {
     if(from > static_cast<From>(std::numeric_limits<To>::max()) ||
        from < static_cast<From>(std::numeric_limits<To>::lowest()) ||