From d4eba794c387521af6919b5ddd83e2027b58f140 Mon Sep 17 00:00:00 2001
From: scrawl <scrawl@baseoftrash.de>
Date: Thu, 17 Dec 2015 23:34:52 +0100
Subject: [PATCH] Add ConstPtr

---
 apps/openmw/mwworld/ptr.cpp | 22 ++++++++++
 apps/openmw/mwworld/ptr.hpp | 81 +++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+)

diff --git a/apps/openmw/mwworld/ptr.cpp b/apps/openmw/mwworld/ptr.cpp
index 4d74c3c58..3f2ef80b6 100644
--- a/apps/openmw/mwworld/ptr.cpp
+++ b/apps/openmw/mwworld/ptr.cpp
@@ -52,3 +52,25 @@ MWWorld::Ptr::operator const void *()
 {
     return mRef;
 }
+
+// -------------------------------------------------------------------------------
+
+const std::string &MWWorld::ConstPtr::getTypeName() const
+{
+    if(mRef != 0)
+        return mRef->mClass->getTypeName();
+    throw std::runtime_error("Can't get type name from an empty object.");
+}
+
+const MWWorld::LiveCellRefBase *MWWorld::ConstPtr::getBase() const
+{
+    if (!mRef)
+        throw std::runtime_error ("Can't access cell ref pointed to by null Ptr");
+
+    return mRef;
+}
+
+MWWorld::ConstPtr::operator const void *()
+{
+    return mRef;
+}
diff --git a/apps/openmw/mwworld/ptr.hpp b/apps/openmw/mwworld/ptr.hpp
index c97d2e6d1..9d370c4cb 100644
--- a/apps/openmw/mwworld/ptr.hpp
+++ b/apps/openmw/mwworld/ptr.hpp
@@ -85,6 +85,87 @@ namespace MWWorld
             ///< Return a 0-pointer, if Ptr is empty; return a non-0-pointer, if Ptr is not empty
     };
 
+    /// \brief Pointer to a const LiveCellRef
+    /// @note a Ptr can be implicitely converted to a ConstPtr, but you can not convert a ConstPtr to a Ptr.
+    class ConstPtr
+    {
+    public:
+
+        const MWWorld::LiveCellRefBase *mRef;
+        const CellStore *mCell;
+        const ContainerStore *mContainerStore;
+
+    public:
+        ConstPtr(const MWWorld::LiveCellRefBase *liveCellRef=0, const CellStore *cell=0)
+          : mRef(liveCellRef), mCell(cell), mContainerStore(0)
+        {
+        }
+
+        ConstPtr(const MWWorld::Ptr& ptr)
+            : mRef(ptr.mRef), mCell(ptr.mCell), mContainerStore(ptr.mContainerStore)
+        {
+        }
+
+        bool isEmpty() const
+        {
+            return mRef == 0;
+        }
+
+        const std::string& getTypeName() const;
+
+        const Class& getClass() const
+        {
+            if(mRef != 0)
+                return *(mRef->mClass);
+            throw std::runtime_error("Cannot get class of an empty object");
+        }
+
+        template<typename T>
+        const MWWorld::LiveCellRef<T> *get() const
+        {
+            const MWWorld::LiveCellRef<T> *ref = dynamic_cast<const MWWorld::LiveCellRef<T>*>(mRef);
+            if(ref) return ref;
+
+            std::stringstream str;
+            str<< "Bad LiveCellRef cast to "<<typeid(T).name()<<" from ";
+            if(mRef != 0) str<< getTypeName();
+            else str<< "an empty object";
+
+            throw std::runtime_error(str.str());
+        }
+
+        const MWWorld::LiveCellRefBase *getBase() const;
+
+        const MWWorld::CellRef& getCellRef() const
+        {
+            assert(mRef);
+            return mRef->mRef;
+        }
+
+        const RefData& getRefData() const
+        {
+            assert(mRef);
+            return mRef->mData;
+        }
+
+        const CellStore *getCell() const
+        {
+            assert(mCell);
+            return mCell;
+        }
+
+        bool isInCell() const
+        {
+            return (mContainerStore == 0) && (mCell != 0);
+        }
+
+        const ContainerStore *getContainerStore() const;
+        ///< May return a 0-pointer, if reference is not in a container.
+
+        operator const void *();
+        ///< Return a 0-pointer, if Ptr is empty; return a non-0-pointer, if Ptr is not empty
+    };
+
     inline bool operator== (const Ptr& left, const Ptr& right)
     {
         return left.mRef==right.mRef;