Merge pull request #2 from larspensjo/ReuseEntity

Bug in allocation of freed entities.

2 files changed, 19 insertions, 5 deletions

diff --git a/entityx/Entity.h b/entityx/Entity.h
index 6d046c3..ae28443 100644
--- a/entityx/Entity.h
+++ b/entityx/Entity.h
@@ -1,10 +1,10 @@
 /**
  * Copyright (C) 2012 Alec Thomas <alec@swapoff.org>
  * All rights reserved.
- * 
+ *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution.
- * 
+ *
  * Author: Alec Thomas <alec@swapoff.org>
  */
 
@@ -227,7 +227,7 @@ class EntityManager : boost::noncopyable {
         return true;
       }
 
-      EntityManager &manager_; 
+      EntityManager &manager_;
       const std::vector<Predicate> predicates_;
       std::vector<boost::function<void (Entity::Id)>> unpackers_;
       Entity::Id i_;
@@ -246,7 +246,7 @@ class EntityManager : boost::noncopyable {
     template <typename A>
     View &unpack_to(boost::shared_ptr<A> &a) {
       unpackers_.push_back(Unpacker<A>(manager_, a));
-      // This resulted in a segfault under clang 4.1 on OSX. No idea why. 
+      // This resulted in a segfault under clang 4.1 on OSX. No idea why.
       /*unpackers_.push_back([&a, this](Entity::Id id) {
         a = manager_.component<A>(id);
       });*/
@@ -299,7 +299,9 @@ class EntityManager : boost::noncopyable {
       id = id_counter_++;
       accomodate_entity(id);
     } else {
-      id = *free_list_.erase(free_list_.begin());
+      auto it = free_list_.begin();
+      id = *it;
+      free_list_.erase(it);
     }
     event_manager_.emit<EntityCreatedEvent>(*this, id);
     return Entity(*this, id);
diff --git a/entityx/Entity_test.cc b/entityx/Entity_test.cc
index 67026e8..d042b4b 100644
--- a/entityx/Entity_test.cc
+++ b/entityx/Entity_test.cc
@@ -75,8 +75,20 @@ class EntityManagerTest : public ::testing::Test {
 
 
 TEST_F(EntityManagerTest, TestCreateEntity) {
+  ASSERT_TRUE(em.size() == 0);
   Entity e = em.create();
   ASSERT_TRUE(em.exists(e));
+  ASSERT_TRUE(em.size() == 1);
+}
+
+TEST_F(EntityManagerTest, TestEntityReuse) {
+  Entity e1 = em.create();
+  auto id = e1.id();
+  em.destroy(e1);
+  ASSERT_TRUE(!em.exists(e1));
+  Entity e2 = em.create();
+  // It is assumed that the allocation will reuse the same entity id.
+  ASSERT_EQ(e2.id(), id);
 }
 
 TEST_F(EntityManagerTest, TestComponentConstruction) {