From 27cc3d297eb00952558d5e4794282cf86b639c16 Mon Sep 17 00:00:00 2001
From: Atlante45 <clement.brisset@gmail.com>
Date: Tue, 13 Jan 2015 20:27:38 -0800
Subject: [PATCH] DependencyManager update

	- Now need a call to DependencyManager::set(...) that support
	  variable arguments number and type
	- Now support destroy operation via DependencyManager::destroy()
	- Now support inheritance. All inheritance relationship need to
	  be specified via DependencyManager::registerInheritance<Base,
Derived>() before any call to the DepedencyManager involving Base.
	- Dependencies should now inherit from the class Dependency as
	  well as using SINGLETON_DEPENDENCY
---
 libraries/shared/src/DependencyManager.cpp |  6 ++
 libraries/shared/src/DependencyManager.h   | 86 ++++++++++++++++------
 2 files changed, 70 insertions(+), 22 deletions(-)

diff --git a/libraries/shared/src/DependencyManager.cpp b/libraries/shared/src/DependencyManager.cpp
index 440c0ac68d..5f78f6bcd5 100644
--- a/libraries/shared/src/DependencyManager.cpp
+++ b/libraries/shared/src/DependencyManager.cpp
@@ -10,3 +10,9 @@
 //
 
 #include "DependencyManager.h"
+
+DependencyManager DependencyManager::_manager;
+
+QSharedPointer<Dependency>& DependencyManager::safeGet(size_t hashCode) {
+    return _instanceHash[hashCode];
+}
\ No newline at end of file
diff --git a/libraries/shared/src/DependencyManager.h b/libraries/shared/src/DependencyManager.h
index 9aecb45657..e996e10590 100644
--- a/libraries/shared/src/DependencyManager.h
+++ b/libraries/shared/src/DependencyManager.h
@@ -12,29 +12,31 @@
 #ifndef hifi_DependencyManager_h
 #define hifi_DependencyManager_h
 
-#include <QSharedPointer>
 #include <QDebug>
+#include <QHash>
+#include <QSharedPointer>
+#include <QWeakPointer>
 
 #include <typeinfo>
 
 #define SINGLETON_DEPENDENCY \
-private:\
-    void customDeleter() {\
-        QObject* thisObject = dynamic_cast<QObject*>(this);\
-        if (thisObject && thisObject->parent()) {\
-            thisObject->deleteLater();\
-        } else {\
-            delete this;\
-        }\
-    }\
     friend class DependencyManager;
 
-class QObject;
+class Dependency {
+protected:
+    virtual ~Dependency() {}
+    virtual void customDeleter() {
+        delete this;
+    }
+
+    friend class DependencyManager;
+};
 
 // usage:
-//     T* instance = DependencyManager::get<T>();
-//     T* instance = DependencyManager::set<T>(Args... args);
-//     T* instance = DependencyManager::destroy<T>();
+//     auto instance = DependencyManager::get<T>();
+//     auto instance = DependencyManager::set<T>(Args... args);
+//     DependencyManager::destroy<T>();
+//     DependencyManager::registerInheritance<Base, Derived>();
 class DependencyManager {
 public:
     template<typename T>
@@ -46,32 +48,72 @@ public:
     template<typename T>
     static void destroy();
     
+    template<typename Base, typename Derived>
+    static void registerInheritance();
+    
 private:
+    static DependencyManager _manager;
+    
     template<typename T>
-    static QSharedPointer<T>& storage();
+    size_t getHashCode();
+    
+    QSharedPointer<Dependency>& safeGet(size_t hashCode);
+    
+    QHash<size_t, QSharedPointer<Dependency>> _instanceHash;
+    QHash<size_t, size_t> _inheritanceHash;
 };
 
 template <typename T>
 QSharedPointer<T> DependencyManager::get() {
-    return storage<T>();
+    static size_t hashCode = _manager.getHashCode<T>();
+    static QWeakPointer<T> instance;
+    
+    if (instance.isNull()) {
+        instance = qSharedPointerCast<T>(_manager.safeGet(hashCode));
+        
+        if (instance.isNull()) {
+            qWarning() << "DependencyManager::get(): No instance available for" << typeid(T).name();
+        }
+    }
+    
+    return instance.toStrongRef();
 }
 
 template <typename T, typename ...Args>
 QSharedPointer<T> DependencyManager::set(Args&&... args) {
+    static size_t hashCode = _manager.getHashCode<T>();
+    
     QSharedPointer<T> instance(new T(args...), &T::customDeleter);
-    storage<T>().swap(instance);
-    return storage<T>();
+    QSharedPointer<Dependency> storedInstance = qSharedPointerCast<Dependency>(instance);
+    _manager.safeGet(hashCode).swap(storedInstance);
+    
+    return instance;
 }
 
 template <typename T>
 void DependencyManager::destroy() {
-    storage<T>().clear();
+    static size_t hashCode = _manager.getHashCode<T>();
+    _manager.safeGet(hashCode).clear();
+}
+
+template<typename Base, typename Derived>
+void DependencyManager::registerInheritance() {
+    size_t baseHashCode = typeid(Base).hash_code();
+    size_t derivedHashCode = typeid(Derived).hash_code();
+    _manager._inheritanceHash.insert(baseHashCode, derivedHashCode);
 }
 
 template<typename T>
-QSharedPointer<T>& DependencyManager::storage() {
-    static QSharedPointer<T> sharedPointer;
-    return sharedPointer;
+size_t DependencyManager::getHashCode() {
+    size_t hashCode = typeid(T).hash_code();
+    auto derivedHashCode = _inheritanceHash.find(hashCode);
+    
+    while (derivedHashCode != _inheritanceHash.end()) {
+        hashCode = derivedHashCode.value();
+        derivedHashCode = _inheritanceHash.find(hashCode);
+    }
+    
+    return hashCode;
 }
 
 #endif // hifi_DependencyManager_h