Pepper_42_C++_interfaces
resource.h
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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>.
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_
void PassRefFromConstructor(PP_Resource resource)
Resource()
The default constructor.
PP_Resource detach()
bool operator==(const pp::Resource &lhs, const pp::Resource &rhs)
Definition: resource.h:97
Resource & operator=(const Resource &other)
virtual ~Resource()
Destructor.
PassRef
Definition: pass_ref.h:17
PP_Resource pp_resource() const
Definition: resource.h:47
bool operator!=(const pp::Resource &lhs, const pp::Resource &rhs)
Definition: resource.h:101
bool is_null() const
Definition: resource.h:45
A generic type used for passing data types between the module and the page.
Definition: var.h:21
A reference counted module resource.
Definition: resource.h:20
void Clear()
Sets this resource to null. This releases ownership of the resource.