source/scriptinterface/ScriptVal.h

   1 /* Copyright (C) 2015 Wildfire Games.
   2  * This file is part of 0 A.D.
   3  *
   4  * 0 A.D. is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * 0 A.D. is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #ifndef INCLUDED_SCRIPTVAL
  19 #define INCLUDED_SCRIPTVAL
  20
  21 #include "ScriptTypes.h"
  22
  23 /**
  24  * A default constructible wrapper around JS::PersistentRootedValue
  25  *
  26  * It's a very common case that we need to store JS::Values on the heap as
  27  * class members and only need them conditionally or want to initialize
  28  * them after the constructor because we don't have the runtime available yet.
  29  * Use it in these cases, but prefer to use JS::PersistentRootedValue directly
  30  * if initializing it with a runtime/context in the constructor isn't a problem.
  31  */
  32  template <typename T>
  33 class DefPersistentRooted
  34 {
  35 public:
  36         DefPersistentRooted()
  37         {
  38         }
  39
  40         DefPersistentRooted(JSRuntime* rt)
  41         {
  42                 m_Val.reset(new JS::PersistentRooted<T>(rt));
  43         }
  44
  45         DefPersistentRooted(JSRuntime* rt, JS::HandleValue val)
  46         {
  47                 m_Val.reset(new JS::PersistentRooted<T>(rt, val));
  48         }
  49
  50         DefPersistentRooted(JSContext* cx, JS::Handle<T> val)
  51         {
  52                 m_Val.reset(new JS::PersistentRooted<T>(cx, val));
  53         }
  54
  55         void clear()
  56         {
  57                 m_Val = nullptr;
  58         }
  59
  60         inline bool uninitialized()
  61         {
  62                 return m_Val == nullptr;
  63         }
  64
  65         inline JS::PersistentRooted<T>& get() const
  66         {
  67                 ENSURE(m_Val);
  68                 return *m_Val;
  69         }
  70
  71         inline void set(JSRuntime* rt, T val)
  72         {
  73                 m_Val.reset(new JS::PersistentRooted<T>(rt, val));
  74         }
  75
  76         inline void set(JSContext* cx, T val)
  77         {
  78                 m_Val.reset(new JS::PersistentRooted<T>(cx, val));
  79         }
  80
  81         // TODO: Move assignment operator and move constructor only have to be
  82         // explicitly defined for Visual Studio. VS2013 is still behind on C++11 support
  83         // What's missing is what they call "Rvalue references v3.0", see
  84         // https://msdn.microsoft.com/en-us/library/hh567368.aspx#rvref
  85         DefPersistentRooted<T>& operator=(DefPersistentRooted<T>&& other)
  86         {
  87                 m_Val = std::move(other.m_Val);
  88                 return *this;
  89         }
  90
  91         DefPersistentRooted<T>(DefPersistentRooted<T>&& other)
  92         {
  93                 m_Val = std::move(other.m_Val);
  94         }
  95
  96 private:
  97         std::unique_ptr<JS::PersistentRooted<T> > m_Val;
  98 };
  99
 100 #endif // INCLUDED_SCRIPTVAL