Add onlyIf precondition

convert_v3_to_v4.py

@@ -23,6 +23,7 @@ def strtobool(val: typing.Union[str, int, bool]) -> bool:
 SCRIPT_DIRECTIVES = [
     "_successIf",
     "_failureIf",
+    "_onlyIf",
     "_skipIf",
     "_while",
     "_onSuccess",

include/behaviortree_cpp/tree_node.h

@@ -47,6 +47,7 @@ enum class PreCond
   // order of the enums also tell us the execution order
   FAILURE_IF = 0,
   SUCCESS_IF,
+  ONLY_IF,
   SKIP_IF,
   WHILE_TRUE,
   COUNT_

src/tree_node.cpp

@@ -194,6 +194,7 @@ Expected<NodeStatus> TreeNode::checkPreConditions()
     }
 
     const PreCond preID = PreCond(index);
+    bool onlyIfIsPresent = false;
 
     // Some preconditions are applied only when the node state is IDLE or SKIPPED
     if(_p->status == NodeStatus::IDLE || _p->status == NodeStatus::SKIPPED)
@@ -209,7 +210,11 @@ Expected<NodeStatus> TreeNode::checkPreConditions()
         {
           return NodeStatus::SUCCESS;
         }
-        else if(preID == PreCond::SKIP_IF)
+        else if(preID == PreCond::ONLY_IF)
+        {
+          onlyIfIsPresent = true;
+        }
+        else if(preID == PreCond::SKIP_IF && onlyIfIsPresent)
         {
           return NodeStatus::SKIPPED;
         }
@@ -219,6 +224,10 @@ Expected<NodeStatus> TreeNode::checkPreConditions()
       {
         return NodeStatus::SKIPPED;
       }
+      else if(preID == PreCond::ONLY_IF)
+      {
+        return NodeStatus::SKIPPED;
+      }
     }
     else if(_p->status == NodeStatus::RUNNING && preID == PreCond::WHILE_TRUE)
     {
@@ -456,6 +465,8 @@ std::string toStr<PreCond>(const PreCond& pre)
       return "_successIf";
     case PreCond::FAILURE_IF:
       return "_failureIf";
+    case PreCond::ONLY_IF:
+      return "_onlyIf";
     case PreCond::SKIP_IF:
       return "_skipIf";
     case PreCond::WHILE_TRUE:

src/xml_parsing.cpp

@@ -1296,6 +1296,7 @@ std::string writeTreeXSD(const BehaviorTreeFactory& factory)
     </xs:complexType>
     <xs:attributeGroup name="preconditionAttributeGroup">
       <xs:attribute name="_failureIf" type="xs:string" use="optional"/>
+      <xs:attribute name="_onlyIf" type="xs:string" use="optional"/>
       <xs:attribute name="_skipIf" type="xs:string" use="optional"/>
       <xs:attribute name="_successIf" type="xs:string" use="optional"/>
       <xs:attribute name="_while" type="xs:string" use="optional"/>

tests/gtest_skipping.cpp

@@ -32,6 +32,33 @@ TEST(SkippingLogic, Sequence)
   ASSERT_EQ(counters[1], 1);
 }
 
+TEST(SkippingLogic, Order)
+{
+  BehaviorTreeFactory factory;
+  std::array<int, 3> counters;
+  RegisterTestTick(factory, "Test", counters);
+
+  const std::string xml_text = R"(
+
+    <root BTCPP_format="4" >
+        <BehaviorTree ID="MainTree">
+            <Sequence>
+                <Script code = "A:=1"/>
+                <TestA _onlyIf="A==1" _skipIf="A==1"/>
+                <TestB _onlyIf="A==0" _skipIf="A==0"/>
+                <TestC _successIf="A==1" _onlyIf="A==1"/>
+            </Sequence>
+        </BehaviorTree>
+    </root>)";
+
+  auto tree = factory.createTreeFromText(xml_text);
+  const auto status = tree.tickWhileRunning();
+  ASSERT_EQ(status, NodeStatus::SUCCESS);
+  ASSERT_EQ(counters[0], 1);
+  ASSERT_EQ(counters[1], 0);
+  ASSERT_EQ(counters[2], 0);
+}
+
 TEST(SkippingLogic, SkipAll)
 {
   BehaviorTreeFactory factory;