From 9ca1072d28cb8d5d2eb40882ad46bcca24d23871 Mon Sep 17 00:00:00 2001
From: Davide Faconti <davide.faconti@eurecat.org>
Date: Tue, 8 Jan 2019 14:24:08 +0100
Subject: [PATCH] Add blackboard scope/hierarchy (issue #44)

---
 gtest/gtest_blackboard.cpp                    | 40 +++++++++++++++++--
 .../behaviortree_cpp/blackboard/blackboard.h  | 34 +++++++++++-----
 2 files changed, 59 insertions(+), 15 deletions(-)

diff --git a/gtest/gtest_blackboard.cpp b/gtest/gtest_blackboard.cpp
index 07af95a69..9b5d51db1 100644
--- a/gtest/gtest_blackboard.cpp
+++ b/gtest/gtest_blackboard.cpp
@@ -55,10 +55,6 @@ class BB_TestNode: public SyncActionNode
 };
 
 
-
-
-/****************TESTS START HERE***************************/
-
 TEST(BlackboardTest, GetInputsFromBlackboard)
 {
     auto bb = Blackboard::create<BlackboardLocal>();
@@ -154,6 +150,42 @@ TEST(BlackboardTest, WithFactory)
     ASSERT_EQ( bb->get<int>("my_output_port_A"), 22 );
     ASSERT_EQ( bb->get<int>("my_output_port_B"), 84 );
     ASSERT_EQ( bb->get<int>("my_input_port"), 84 );
+}
+
+TEST(BlackboardTest, NestedBlackboards)
+{
+
+    auto bb_A = Blackboard::create<BlackboardLocal>();
+    auto bb_B = Blackboard::create<BlackboardLocal>();
+    auto bb_C = Blackboard::create<BlackboardLocal>();
+
+    bb_B->setParentBlackboard( bb_A );
+    bb_C->setParentBlackboard( bb_B );
+
+    bb_A->set("value", 11);
+    bb_B->set("value", 22);
+    bb_C->set("value", 33);
+
+    bb_A->set("number", 44);
+    bb_B->set("number", 55);
+
+    bb_A->set("answer", 66);
+
+    ASSERT_EQ( bb_A->get<int>("value"), 11 );
+    ASSERT_EQ( bb_B->get<int>("value"), 22 );
+    ASSERT_EQ( bb_C->get<int>("value"), 33 );
+
+    ASSERT_EQ( bb_A->get<int>("number"), 44 );
+    ASSERT_EQ( bb_B->get<int>("number"), 55 );
+    ASSERT_EQ( bb_C->get<int>("number"), 55 );
+
+    ASSERT_EQ( bb_A->get<int>("answer"), 66 );
+    ASSERT_EQ( bb_B->get<int>("answer"), 66 );
+    ASSERT_EQ( bb_C->get<int>("answer"), 66 );
+
 
+    ASSERT_ANY_THROW( bb_A->get<int>("not_there") );
+    ASSERT_ANY_THROW( bb_B->get<int>("not_there") );
+    ASSERT_ANY_THROW( bb_C->get<int>("not_there") );
 }
 
diff --git a/include/behaviortree_cpp/blackboard/blackboard.h b/include/behaviortree_cpp/blackboard/blackboard.h
index 400b837c9..c103d9643 100644
--- a/include/behaviortree_cpp/blackboard/blackboard.h
+++ b/include/behaviortree_cpp/blackboard/blackboard.h
@@ -73,17 +73,12 @@ class Blackboard
     template <typename T>
     bool get(const std::string& key, T& value) const
     {
-        const SafeAny::Any* val = nullptr;
+        const SafeAny::Any* val = getAny(key);
+        if (val)
         {
-            std::unique_lock<std::mutex> lock(mutex_);
-            val = impl_->get(key);
+            value = val->cast<T>();
         }
-        if (!val)
-        {
-            return false;
-        }
-        value = val->cast<T>();
-        return true;
+        return (bool)val;
     }
 
     /**
@@ -95,7 +90,17 @@ class Blackboard
     const SafeAny::Any* getAny(const std::string& key) const
     {
         std::unique_lock<std::mutex> lock(mutex_);
-        return impl_->get(key);
+        auto val = impl_->get(key);
+
+        if (!val) // not found. try the parent
+        {
+            if( auto parent_bb = parent_blackboard_.lock() )
+            {
+                // this should work recursively
+                val = parent_bb->getAny(key);
+            }
+        }
+        return val;
     }
 
     /**
@@ -113,6 +118,11 @@ class Blackboard
         return value;
     }
 
+    void setParentBlackboard(const Blackboard::Ptr& parent_bb )
+    {
+        parent_blackboard_ = parent_bb;
+    }
+
     /// Update the entry with the given key
     template <typename T>
     void set(const std::string& key, const T& value)
@@ -131,7 +141,9 @@ class Blackboard
   private:
     std::unique_ptr<BlackboardImpl> impl_;
     mutable std::mutex mutex_;
+    mutable std::weak_ptr<Blackboard> parent_blackboard_;
 };
-}
+
+} // end namespace
 
 #endif   // BLACKBOARD_H