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 /// A reference counted module resource.
  18 class Resource {
  19  public:
  20   /// The default constructor.
  21   Resource();
  22
  23   /// A constructor for copying a resource.
  24   ///
  25   /// @param[in] other A <code>Resource</code>.
  26   Resource(const Resource& other);
  27
  28   /// Destructor.
  29   virtual ~Resource();
  30
  31   /// This function assigns one <code>Resource</code> to another
  32   /// <code>Resource</code>.
  33   ///
  34   /// @param[in] other A Resource.
  35   ///
  36   /// @return A Resource containing the assigned Resource.
  37   Resource& operator=(const Resource& other);
  38
  39   /// This functions determines if this resource is invalid or
  40   /// uninitialized.
  41   ///
  42   /// @return true if this resource is invalid or uninitialized.
  43   bool is_null() const { return !pp_resource_; }
  44
  45   PP_Resource pp_resource() const { return pp_resource_; }
  46
  47   /// This function releases ownership of this resource and returns it to the
  48   /// caller.
  49   ///
  50   /// Note that the reference count on the resource is unchanged and the caller
  51   /// needs to release the resource.
  52   ///
  53   /// @return The detached <code>PP_Resource</code>.
  54   PP_Resource detach();
  55
  56  protected:
  57   /// A constructor used when a <code>PP_Resource</code> is provided as a
  58   /// return value whose reference count we need to increment.
  59   ///
  60   /// @param[in] resource A <code>PP_Resource</code> corresponding to a
  61   /// resource.
  62   explicit Resource(PP_Resource resource);
  63
  64   /// Constructor used when a <code>PP_Resource</code> already has a ref count
  65   /// assigned. Add additional refcount is not taken.
  66   Resource(PassRef, PP_Resource resource);
  67
  68   /// PassRefFromConstructor is called by derived class' constructors to
  69   /// initialize this <code>Resource</code> with a <code>PP_Resource</code>
  70   /// that has already had its reference count incremented by
  71   /// <code>Core::AddRefResource</code>. It also assumes this object has no
  72   /// current resource.
  73   ///
  74   /// The intended usage of this function that the derived class constructor
  75   /// will call the default <code>Resource</code> constructor, then make a call
  76   /// to create a resource. It then wants to assign the new resource (which,
  77   /// since it was returned by the browser, already had its reference count
  78   /// increased).
  79   ///
  80   /// @param[in] resource A <code>PP_Resource</code> corresponding to a
  81   /// resource.
  82   void PassRefFromConstructor(PP_Resource resource);
  83
  84  private:
  85   PP_Resource pp_resource_;
  86 };
  87
  88 }  // namespace pp
  89
  90 inline bool operator==(const pp::Resource& lhs, const pp::Resource& rhs) {
  91   return lhs.pp_resource() == rhs.pp_resource();
  92 }
  93
  94 inline bool operator!=(const pp::Resource& lhs, const pp::Resource& rhs) {
  95   return !(lhs == rhs);
  96 }
  97
  98 #endif // PPAPI_CPP_RESOURCE_H_