ppapi/cpp/resource.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef PPAPI_CPP_RESOURCE_H_
   6 #define PPAPI_CPP_RESOURCE_H_
   7
   8 #include "ppapi/c/pp_resource.h"
   9 #include "ppapi/cpp/instance_handle.h"
  10 #include "ppapi/cpp/pass_ref.h"
  11
  12 /// @file
  13 /// This file defines a <code>Resource</code> type representing data associated
  14 /// with the module.
  15 namespace pp {
  16
  17 class Var;
  18
  19 /// A reference counted module resource.
  20 class Resource {
  21  public:
  22   /// The default constructor.
  23   Resource();
  24
  25   /// A constructor for copying a resource.
  26   ///
  27   /// @param[in] other A <code>Resource</code>.
  28   Resource(const Resource& other);
  29
  30   /// Destructor.
  31   virtual ~Resource();
  32
  33   /// This function assigns one <code>Resource</code> to another
  34   /// <code>Resource</code>.
  35   ///
  36   /// @param[in] other A Resource.
  37   ///
  38   /// @return A Resource containing the assigned Resource.
  39   Resource& operator=(const Resource& other);
  40
  41   /// This functions determines if this resource is invalid or
  42   /// uninitialized.
  43   ///
  44   /// @return true if this resource is invalid or uninitialized.
  45   bool is_null() const { return !pp_resource_; }
  46
  47   PP_Resource pp_resource() const { return pp_resource_; }
  48
  49   /// This function releases ownership of this resource and returns it to the
  50   /// caller.
  51   ///
  52   /// Note that the reference count on the resource is unchanged and the caller
  53   /// needs to release the resource.
  54   ///
  55   /// @return The detached <code>PP_Resource</code>.
  56   PP_Resource detach();
  57
  58  protected:
  59   /// A constructor used when a <code>PP_Resource</code> is provided as a
  60   /// return value whose reference count we need to increment.
  61   ///
  62   /// @param[in] resource A <code>PP_Resource</code> corresponding to a
  63   /// resource.
  64   explicit Resource(PP_Resource resource);
  65
  66   /// Constructor used when a <code>PP_Resource</code> already has a ref count
  67   /// assigned. Add additional refcount is not taken.
  68   Resource(PassRef, PP_Resource resource);
  69
  70   /// PassRefFromConstructor is called by derived class' constructors to
  71   /// initialize this <code>Resource</code> with a <code>PP_Resource</code>
  72   /// that has already had its reference count incremented by
  73   /// <code>Core::AddRefResource</code>. It also assumes this object has no
  74   /// current resource.
  75   ///
  76   /// The intended usage of this function that the derived class constructor
  77   /// will call the default <code>Resource</code> constructor, then make a call
  78   /// to create a resource. It then wants to assign the new resource (which,
  79   /// since it was returned by the browser, already had its reference count
  80   /// increased).
  81   ///
  82   /// @param[in] resource A <code>PP_Resource</code> corresponding to a
  83   /// resource.
  84   void PassRefFromConstructor(PP_Resource resource);
  85
  86   /// Sets this resource to null. This releases ownership of the resource.
  87   void Clear();
  88
  89  private:
  90   friend class Var;
  91
  92   PP_Resource pp_resource_;
  93 };
  94
  95 }  // namespace pp
  96
  97 inline bool operator==(const pp::Resource& lhs, const pp::Resource& rhs) {
  98   return lhs.pp_resource() == rhs.pp_resource();
  99 }
 100
 101 inline bool operator!=(const pp::Resource& lhs, const pp::Resource& rhs) {
 102   return !(lhs == rhs);
 103 }
 104
 105 #endif // PPAPI_CPP_RESOURCE_H_