add the ability to register multiple BTs (#373)

Author: facontidavide

examples/CMakeLists.txt

@@ -52,3 +52,5 @@ if(CURSES_FOUND)
     target_link_libraries(t12_ncurses_manual_selector  ${BEHAVIOR_TREE_LIBRARY} bt_sample_nodes )
 endif()
 
+add_executable(t13_load_multiple_BTs  t13_load_multiple_BTs.cpp )
+target_link_libraries(t13_load_multiple_BTs  ${BEHAVIOR_TREE_LIBRARY} bt_sample_nodes )

examples/t13_load_multiple_BTs.cpp

@@ -0,0 +1,84 @@
+#include "dummy_nodes.h"
+#include "behaviortree_cpp_v3/bt_factory.h"
+
+
+/** This example show how it is possible to:
+ * - load BehaviorTrees from multiple files manually (without the <include> tag)
+ * - instantiate a specific tree, instead of the one specified by [main_tree_to_execute]
+ */
+
+// clang-format off
+
+static const char* xml_text_main = R"(
+<root main_tree_to_execute="MainTree">
+    <BehaviorTree ID="MainTree">
+        <Sequence>
+            <SaySomething message="starting MainTree" />
+            <SubTree ID="SubA"/>
+            <SubTree ID="SubB"/>
+        </Sequence>
+    </BehaviorTree>
+</root>  )";
+
+static const char* xml_text_subA = R"(
+<root>
+    <BehaviorTree ID="SubA">
+        <SaySomething message="Executing SubA" />
+    </BehaviorTree>
+</root>  )";
+
+static const char* xml_text_subB = R"(
+<root>
+    <BehaviorTree ID="SubB">
+        <SaySomething message="Executing SubB" />
+    </BehaviorTree>
+</root>  )";
+
+// clang-format on
+
+using namespace BT;
+
+int main()
+{
+    BT::BehaviorTreeFactory factory;
+    factory.registerNodeType<DummyNodes::SaySomething>("SaySomething");
+
+    // Register the behavior tree definitions, but do not instantiate them yet.
+    // Order is not important.
+    factory.registerBehaviorTreeFromText(xml_text_subA);
+    factory.registerBehaviorTreeFromText(xml_text_subB);
+    factory.registerBehaviorTreeFromText(xml_text_main);
+
+    //Check that the BTs have been registered correctly
+    std::cout << "Registered BehaviorTrees:" << std::endl;
+    for(const std::string& bt_name: factory.registeredBehaviorTrees())
+    {
+        std::cout << " - " << bt_name << std::endl;
+    }
+
+    // You can create the MainTree and the subtrees will be added automatically.
+    std::cout << "----- MainTree tick ----" << std::endl;
+    auto main_tree = factory.createdTree("MainTree");
+    main_tree.tickRoot();
+
+    // ... or you can create only one of the subtree
+    std::cout << "----- SubA tick ----" << std::endl;
+    auto subA_tree = factory.createdTree("SubA");
+    subA_tree.tickRoot();
+
+    return 0;
+}
+/* Expected output:
+
+Registered BehaviorTrees:
+ - MainTree
+ - SubA
+ - SubB
+----- MainTree tick ----
+Robot says: starting MainTree
+Robot says: Executing SubA
+Robot says: Executing SubB
+----- SubA tick ----
+Robot says: Executing SubA
+
+*/

include/behaviortree_cpp_v3/bt_factory.h

@@ -22,7 +22,6 @@
 #include <algorithm>
 #include <set>
 
-
 #include "behaviortree_cpp_v3/behavior_tree.h"
 
 namespace BT
@@ -197,6 +196,8 @@ class Tree
 
 };
 
+class Parser;
+
 /**
  * @brief The BehaviorTreeFactory is used to create instances of a
  * TreeNode at run-time.
@@ -270,6 +271,12 @@ class BehaviorTreeFactory
      */
     void registerFromROSPlugins();
 
+    void registerBehaviorTreeFromFile(const std::string& filename);
+
+    void registerBehaviorTreeFromText(const std::string& xml_text);
+
+    std::vector<std::string> registeredBehaviorTrees() const;
+
     /**
      * @brief instantiateTreeNode creates an instance of a previously registered TreeNode.
      *
@@ -374,11 +381,16 @@ class BehaviorTreeFactory
     Tree createTreeFromFile(const std::string& file_path,
                             Blackboard::Ptr blackboard = Blackboard::create());
 
+    Tree createdTree(const std::string& tree_name,
+                     Blackboard::Ptr blackboard = Blackboard::create());
+
 private:
     std::unordered_map<std::string, NodeBuilder> builders_;
     std::unordered_map<std::string, TreeNodeManifest> manifests_;
     std::set<std::string> builtin_IDs_;
+    std::unordered_map<std::string, Any> behavior_tree_definitions_;
 
+    std::shared_ptr<BT::Parser> parser_;
     // clang-format on
 };
 

include/behaviortree_cpp_v3/bt_parser.h

@@ -21,11 +21,13 @@ class Parser
     Parser(const Parser& other) = delete;
     Parser& operator=(const Parser& other) = delete;
 
-    virtual void loadFromFile(const std::string& filename) = 0;
+    virtual void loadFromFile(const std::string& filename, bool add_includes = true) = 0;
 
-    virtual void loadFromText(const std::string& xml_text) = 0;
+    virtual void loadFromText(const std::string& xml_text, bool add_includes = true) = 0;
 
-    virtual Tree instantiateTree(const Blackboard::Ptr &root_blackboard) = 0;
+    virtual std::vector<std::string> registeredBehaviorTrees() const = 0;
+
+    virtual Tree instantiateTree(const Blackboard::Ptr &root_blackboard, std::string tree_name = {}) = 0;
 };
 
 }

include/behaviortree_cpp_v3/xml_parsing.h

@@ -16,16 +16,19 @@ class XMLParser: public Parser
   public:
     XMLParser(const BehaviorTreeFactory& factory);
 
-    ~XMLParser();
+    ~XMLParser() override;
 
     XMLParser(const XMLParser& other) = delete;
     XMLParser& operator=(const XMLParser& other) = delete;
 
-    void loadFromFile(const std::string& filename) override;
+    void loadFromFile(const std::string& filename, bool add_includes = true) override;
 
-    void loadFromText(const std::string& xml_text) override;
+    void loadFromText(const std::string& xml_text, bool add_includes = true) override;
 
-    Tree instantiateTree(const Blackboard::Ptr &root_blackboard) override;
+    std::vector<std::string> registeredBehaviorTrees() const override;
+
+    Tree instantiateTree(const Blackboard::Ptr &root_blackboard,
+                         std::string main_tree_to_execute = {}) override;
 
   private:
 

src/bt_factory.cpp

@@ -10,9 +10,11 @@
 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 
+#include <fstream>
 #include "behaviortree_cpp_v3/bt_factory.h"
 #include "behaviortree_cpp_v3/utils/shared_library.h"
 #include "behaviortree_cpp_v3/xml_parsing.h"
+#include "private/tinyxml2.h"
 
 #ifdef USING_ROS
 #include "filesystem/path.h"
@@ -23,6 +25,7 @@ namespace BT
 {
 BehaviorTreeFactory::BehaviorTreeFactory()
 {
+    parser_ = std::make_shared<XMLParser>(*this);
     registerNodeType<FallbackNode>("Fallback");
     registerNodeType<SequenceNode>("Sequence");
     registerNodeType<SequenceStarNode>("SequenceStar");
@@ -212,6 +215,22 @@ void BehaviorTreeFactory::registerFromROSPlugins()
     }
 #endif
 
+
+void BehaviorTreeFactory::registerBehaviorTreeFromFile(const std::string &filename)
+{
+    parser_->loadFromFile(filename);
+}
+
+void BehaviorTreeFactory::registerBehaviorTreeFromText(const std::string &xml_text)
+{
+    parser_->loadFromText(xml_text);
+}
+
+std::vector<std::string> BehaviorTreeFactory::registeredBehaviorTrees() const
+{
+    return parser_->registeredBehaviorTrees();
+}
+
 std::unique_ptr<TreeNode> BehaviorTreeFactory::instantiateTreeNode(
         const std::string& name,
         const std::string& ID,
@@ -268,6 +287,13 @@ Tree BehaviorTreeFactory::createTreeFromFile(const std::string &file_path,
     return tree;
 }
 
+Tree BehaviorTreeFactory::createdTree(const std::string &tree_name, Blackboard::Ptr blackboard)
+{
+    auto tree = parser_->instantiateTree(blackboard, tree_name);
+    tree.manifests = this->manifests();
+    return tree;
+}
+
 Tree::~Tree()
 {
     haltTree();