text: // Copyright (c) 2011 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef PPAPI_CPP_RESOURCE_H_
  #define PPAPI_CPP_RESOURCE_H_
  
  #include "ppapi/c/pp_resource.h"
  #include "ppapi/cpp/instance_handle.h"
  #include "ppapi/cpp/pass_ref.h"
  
  /// @file
  /// This file defines a <code>Resource</code> type representing data associated
  /// with the module.
  namespace pp {
  
  class Var;
  
  /// A reference counted module resource.
  class Resource {
   public:
    /// The default constructor.
    Resource();
  
    /// A constructor for copying a resource.
    ///
    /// @param[in] other A <code>Resource</code>.
    Resource(const Resource& other);
  
    /// Destructor.
    virtual ~Resource();
  
    /// This function assigns one <code>Resource</code> to another
    /// <code>Resource</code>.
    ///
    /// @param[in] other A Resource.
    ///
    /// @return A Resource containing the assigned Resource.
    Resource& operator=(const Resource& other);
  
    /// This functions determines if this resource is invalid or
    /// uninitialized.
    ///
    /// @return true if this resource is invalid or uninitialized.
    bool is_null() const { return !pp_resource_; }
  
    PP_Resource pp_resource() const { return pp_resource_; }
  
    /// This function releases ownership of this resource and returns it to the
    /// caller.
    ///
    /// Note that the reference count on the resource is unchanged and the caller
    /// needs to release the resource.
    ///
    /// @return The detached <code>PP_Resource</code>.
    PP_Resource detach();
  
   protected:
    /// A constructor used when a <code>PP_Resource</code> is provided as a
    /// return value whose reference count we need to increment.
    ///
    /// @param[in] resource A <code>PP_Resource</code> corresponding to a
    /// resource.
    explicit Resource(PP_Resource resource);
  
    /// Constructor used when a <code>PP_Resource</code> already has a ref count
    /// assigned. Add additional refcount is not taken.
    Resource(PassRef, PP_Resource resource);
  
    /// PassRefFromConstructor is called by derived class' constructors to
    /// initialize this <code>Resource</code> with a <code>PP_Resource</code>
    /// that has already had its reference count incremented by
    /// <code>Core::AddRefResource</code>. It also assumes this object has no
    /// current resource.
    ///
    /// The intended usage of this function that the derived class constructor
    /// will call the default <code>Resource</code> constructor, then make a call
    /// to create a resource. It then wants to assign the new resource (which,
    /// since it was returned by the browser, already had its reference count
    /// increased).
    ///
    /// @param[in] resource A <code>PP_Resource</code> corresponding to a
    /// resource.
    void PassRefFromConstructor(PP_Resource resource);
  
    /// Sets this resource to null. This releases ownership of the resource.
    void Clear();
  
   private:
    friend class Var;
  
    PP_Resource pp_resource_;
  };
  
  }  // namespace pp
  
  inline bool operator==(const pp::Resource& lhs, const pp::Resource& rhs) {
    return lhs.pp_resource() == rhs.pp_resource();
  }
  
  inline bool operator!=(const pp::Resource& lhs, const pp::Resource& rhs) {
    return !(lhs == rhs);
  }
  
  #endif // PPAPI_CPP_RESOURCE_H_
  