Fix #948: parseString supports enums with convertFromString specializations

Author: facontidavide

include/behaviortree_cpp/tree_node.h

@@ -20,6 +20,7 @@
 #include "behaviortree_cpp/utils/strcat.hpp"
 #include "behaviortree_cpp/utils/wakeup_signal.hpp"
 
+#include <charconv>
 #include <exception>
 #include <map>
 #include <utility>
@@ -432,17 +433,25 @@ T TreeNode::parseString(const std::string& str) const
 {
   if constexpr(std::is_enum_v<T> && !std::is_same_v<T, NodeStatus>)
   {
-    auto it = config().enums->find(str);
-    // conversion available
-    if(it != config().enums->end())
+    // Check the ScriptingEnumsRegistry first, if available.
+    if(config().enums)
     {
-      return static_cast<T>(it->second);
+      auto it = config().enums->find(str);
+      if(it != config().enums->end())
+      {
+        return static_cast<T>(it->second);
+      }
     }
-    else
+    // Try numeric conversion (e.g. "2" for an enum value).
+    int tmp = 0;
+    auto [ptr, ec] = std::from_chars(str.data(), str.data() + str.size(), tmp);
+    if(ec == std::errc() && ptr == str.data() + str.size())
     {
-      // hopefully str contains a number that can be parsed. May throw
-      return static_cast<T>(convertFromString<int>(str));
+      return static_cast<T>(tmp);
     }
+    // Fall back to convertFromString<T>, which uses a user-provided
+    // specialization if one exists. Issue #948.
+    return convertFromString<T>(str);
   }
   return convertFromString<T>(str);
 }

tests/gtest_enums.cpp

@@ -240,3 +240,68 @@ TEST(Enums, SubtreeRemapping)
   ASSERT_EQ(status, NodeStatus::SUCCESS);
   ASSERT_EQ(tree.rootBlackboard()->get<BatteryStatus>("fault_status"), LOW_BATTERY);
 }
+
+// Issue #948: enums with a convertFromString<T> specialization should be parsed
+// correctly via getInput, without requiring ScriptingEnumsRegistry.
+class ActionWithNodeType : public SyncActionNode
+{
+public:
+  ActionWithNodeType(const std::string& name, const NodeConfig& config)
+    : SyncActionNode(name, config)
+  {}
+
+  NodeStatus tick() override
+  {
+    auto res = getInput<NodeType>("type");
+    if(!res)
+    {
+      throw RuntimeError("getInput failed: " + res.error());
+    }
+    parsed_type = res.value();
+    return NodeStatus::SUCCESS;
+  }
+
+  static PortsList providedPorts()
+  {
+    return { InputPort<NodeType>("type") };
+  }
+
+  NodeType parsed_type = NodeType::UNDEFINED;
+};
+
+TEST(Enums, ParseEnumWithConvertFromString_Issue948)
+{
+  std::string xml_txt = R"(
+    <root BTCPP_format="4" >
+      <BehaviorTree ID="Main">
+        <Sequence>
+          <ActionWithNodeType name="test_action" type="Action"/>
+          <ActionWithNodeType name="test_control" type="Control"/>
+        </Sequence>
+      </BehaviorTree>
+    </root>)";
+
+  BehaviorTreeFactory factory;
+  factory.registerNodeType<ActionWithNodeType>("ActionWithNodeType");
+  // Deliberately NOT registering NodeType in ScriptingEnumsRegistry.
+  // convertFromString<NodeType> exists and should be used as fallback.
+
+  auto tree = factory.createTreeFromText(xml_txt);
+  NodeStatus status = tree.tickWhileRunning();
+  ASSERT_EQ(status, NodeStatus::SUCCESS);
+
+  for(const auto& node : tree.subtrees.front()->nodes)
+  {
+    if(auto typed = dynamic_cast<ActionWithNodeType*>(node.get()))
+    {
+      if(typed->name() == "test_action")
+      {
+        ASSERT_EQ(NodeType::ACTION, typed->parsed_type);
+      }
+      else if(typed->name() == "test_control")
+      {
+        ASSERT_EQ(NodeType::CONTROL, typed->parsed_type);
+      }
+    }
+  }
+}