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Enable interpretation of subtree ports as numbers. #23

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Merged
JWhitleyWork merged 2 commits into from
Apr 27, 2026
Merged

Enable interpretation of subtree ports as numbers. #23

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ce843bc
Revert "Preserve numeric types for literal subtree port values"
dsobek Apr 27, 2026
959730c
Allow for strongly typed numbers to be added with non-strongly typed …
dsobek Apr 27, 2026
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6 changes: 5 additions & 1 deletion include/behaviortree_cpp/scripting/operators.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -213,7 +213,11 @@ struct ExprBinaryArithmetic : ExprBase
throw RuntimeError(ErrorNotInit("right", opStr()));
}

if(rhs_v.isNumber() && lhs_v.isNumber())
// If just one value is strongly typed as a number, and the other can be casted to one, do arithmetic. If both are not strongly typed, continue. In the case of `+`, non-strongly typed values will result in concatenation.
bool are_numbers = (rhs_v.isNumber() && lhs_v.isNumber()) ||
((rhs_v.tryCast<double>().has_value() && lhs_v.isNumber()) !=
(rhs_v.isNumber() && lhs_v.tryCast<double>().has_value()));
if(are_numbers)
{
auto lv = lhs_v.cast<double>();
auto rv = rhs_v.cast<double>();
Expand Down
55 changes: 2 additions & 53 deletions src/xml_parsing.cpp
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Expand Up @@ -12,12 +12,10 @@

#include <algorithm>
#include <cctype>
#include <charconv>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iostream>
#include <limits>
#include <list>
#include <sstream>
#include <string>
Expand Down Expand Up @@ -1008,59 +1006,10 @@ void BT::XMLParser::PImpl::recursivelyCreateSubtree(const std::string& tree_ID,
}
else
{
// constant value: set it into the BB with appropriate type
// constant string: just set that constant value into the BB
// IMPORTANT: this must not be autoremapped!!!
new_bb->enableAutoRemapping(false);
const std::string str_value(port_value);

// Try to preserve numeric types so that Script expressions
// can perform arithmetic without type-mismatch errors.
// Use std::from_chars with strict full-string validation to avoid
// false positives on compound strings like "1;2;3" or "2.2;2.4".
bool stored = false;
if(!str_value.empty())
{
const char* begin = str_value.data();
const char* end = begin + str_value.size();
// Try integer first (no decimal point, no exponent notation).
// Use int when the value fits, to match the most common port
// declarations. Fall back to int64_t for larger values.
if(str_value.find('.') == std::string::npos &&
str_value.find('e') == std::string::npos &&
str_value.find('E') == std::string::npos)
{
int64_t int_val = 0;
auto [ptr, ec] = std::from_chars(begin, end, int_val);
if(ec == std::errc() && ptr == end)
{
if(int_val >= std::numeric_limits<int>::min() &&
int_val <= std::numeric_limits<int>::max())
{
new_bb->set(port_name, static_cast<int>(int_val));
}
else
{
new_bb->set(port_name, int_val);
}
stored = true;
}
}
// Try double
if(!stored)
{
double dbl_val = 0;
auto [ptr, ec] = std::from_chars(begin, end, dbl_val);
if(ec == std::errc() && ptr == end)
{
new_bb->set(port_name, dbl_val);
stored = true;
}
}
}
if(!stored)
{
new_bb->set(port_name, str_value);
}
new_bb->set(port_name, static_cast<std::string>(port_value));
new_bb->enableAutoRemapping(do_autoremap);
}
}
Expand Down
108 changes: 70 additions & 38 deletions tests/gtest_subtree.cpp
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Expand Up @@ -332,6 +332,76 @@ TEST(SubTree, StringConversions_Issue530)
tree.tickOnce();
}

// Regression test for https://github.com/PickNikRobotics/moveit_pro/issues/18587.
TEST(SubTree, ScriptingTypingIssue)
{
static const char* xml_text = R"(

<root BTCPP_format="4" >
<BehaviorTree ID="MainTree">
<Sequence>
<SubTree ID="mySubtree" in_value="1.0" out_value="{y}" />
</Sequence>
</BehaviorTree>

<BehaviorTree ID="mySubtree">
<Script code = "out_value := in_value + 1" />
</BehaviorTree>
<TreeNodesModel>
<SubTree ID="mySubtree">
<input_port name="in_value" />
<output_port name="out_value" />
</SubTree>
</TreeNodesModel>
</root> )";

BehaviorTreeFactory factory;
factory.registerBehaviorTreeFromText(xml_text);

auto blackboard = BT::Blackboard::create();
Tree tree = factory.createTree("MainTree", blackboard);

auto status = tree.tickWhileRunning();
ASSERT_EQ(status, NodeStatus::SUCCESS);

EXPECT_EQ(blackboard->get<int>("y"), 2);
}

// Test to make sure that the fix for the addressed bug above doesn't cause another regression: string concatenation with `+` should still work... for now.
TEST(SubTree, ScriptingTypingIssue_StringConcatWorks)
{
static const char* xml_text = R"(

<root BTCPP_format="4" >
<BehaviorTree ID="MainTree">
<Sequence>
<SubTree ID="mySubtree" in_value="12" out_value="{y}" />
</Sequence>
</BehaviorTree>

<BehaviorTree ID="mySubtree">
<Script code = "out_value := in_value + '34'" />
</BehaviorTree>
<TreeNodesModel>
<SubTree ID="mySubtree">
<input_port name="in_value" />
<output_port name="out_value" />
</SubTree>
</TreeNodesModel>
</root> )";

BehaviorTreeFactory factory;
factory.registerBehaviorTreeFromText(xml_text);

auto blackboard = BT::Blackboard::create();
Tree tree = factory.createTree("MainTree", blackboard);

auto status = tree.tickWhileRunning();
ASSERT_EQ(status, NodeStatus::SUCCESS);

EXPECT_EQ(blackboard->get<std::string>("y"), "1234");
}

class NaughtyNav2Node : public BT::SyncActionNode
{
public:
Expand Down Expand Up @@ -799,41 +869,3 @@ TEST(SubTree, SubtreeNameNotRegistered)
ASSERT_ANY_THROW(auto tree = factory.createTreeFromText(xml_text));
ASSERT_ANY_THROW(factory.registerBehaviorTreeFromText(xml_text));
}

// Regression test: literal numeric values passed to subtrees should preserve
// their numeric type so that Script expressions can do arithmetic.
TEST(SubTree, LiteralNumericPortsPreserveType)
{
// clang-format off
static const char* xml_text = R"(
<root BTCPP_format="4" main_tree_to_execute="MainTree">

<BehaviorTree ID="MainTree">
<Sequence>
<SubTree ID="DoMath" int_val="42" dbl_val="3.14" str_val="hello"
remapped_val="{from_parent}" />
</Sequence>
</BehaviorTree>

<BehaviorTree ID="DoMath">
<Sequence>
<ScriptCondition code=" int_val + 1 == 43 " />
<ScriptCondition code=" dbl_val > 3.0 " />
<ScriptCondition code=" remapped_val + 1 == 101 " />
</Sequence>
</BehaviorTree>

</root>
)";
// clang-format on

BehaviorTreeFactory factory;

auto tree = factory.createTreeFromText(xml_text);

// Set the remapped parent value as an integer
tree.rootBlackboard()->set("from_parent", 100);

const auto status = tree.tickWhileRunning();
ASSERT_EQ(status, NodeStatus::SUCCESS);
}
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