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      1 // Copyright 2014 The Chromium OS 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 LIBBRILLO_BRILLO_DBUS_DBUS_PROPERTY_H_
      6 #define LIBBRILLO_BRILLO_DBUS_DBUS_PROPERTY_H_
      7 
      8 #include <brillo/dbus/data_serialization.h>
      9 #include <dbus/property.h>
     10 
     11 namespace brillo {
     12 namespace dbus_utils {
     13 
     14 // Re-implementation of dbus::Property<T> that can handle any type supported by
     15 // D-Bus data serialization layer, such as vectors, maps, tuples, etc.
     16 // This class is pretty much a copy of dbus::Property<T> from dbus/property.h
     17 // except that it provides the implementations for PopValueFromReader and
     18 // AppendSetValueToWriter.
     19 template<class T>
     20 class Property : public dbus::PropertyBase {
     21  public:
     22   Property() = default;
     23 
     24   // Retrieves the cached value.
     25   const T& value() const { return value_; }
     26 
     27   // Requests an updated value from the remote object incurring a
     28   // round-trip. |callback| will be called when the new value is available.
     29   // This may not be implemented by some interfaces.
     30   void Get(dbus::PropertySet::GetCallback callback) {
     31     property_set()->Get(this, callback);
     32   }
     33 
     34   // Synchronous vesion of Get().
     35   bool GetAndBlock() {
     36     return property_set()->GetAndBlock(this);
     37   }
     38 
     39   // Requests that the remote object change the property value to |value|,
     40   // |callback| will be called to indicate the success or failure of the
     41   // request, however the new value may not be available depending on the
     42   // remote object.
     43   void Set(const T& value, dbus::PropertySet::SetCallback callback) {
     44     set_value_ = value;
     45     property_set()->Set(this, callback);
     46   }
     47 
     48   // Synchronous version of Set().
     49   bool SetAndBlock(const T& value) {
     50     set_value_ = value;
     51     return property_set()->SetAndBlock(this);
     52   }
     53 
     54   // Method used by PropertySet to retrieve the value from a MessageReader,
     55   // no knowledge of the contained type is required, this method returns
     56   // true if its expected type was found, false if not.
     57   bool PopValueFromReader(dbus::MessageReader* reader) override {
     58     return PopVariantValueFromReader(reader, &value_);
     59   }
     60 
     61   // Method used by PropertySet to append the set value to a MessageWriter,
     62   // no knowledge of the contained type is required.
     63   // Implementation provided by specialization.
     64   void AppendSetValueToWriter(dbus::MessageWriter* writer) override {
     65     AppendValueToWriterAsVariant(writer, set_value_);
     66   }
     67 
     68   // Method used by test and stub implementations of dbus::PropertySet::Set
     69   // to replace the property value with the set value without using a
     70   // dbus::MessageReader.
     71   void ReplaceValueWithSetValue() override {
     72     value_ = set_value_;
     73     property_set()->NotifyPropertyChanged(name());
     74   }
     75 
     76   // Method used by test and stub implementations to directly set the
     77   // value of a property.
     78   void ReplaceValue(const T& value) {
     79     value_ = value;
     80     property_set()->NotifyPropertyChanged(name());
     81   }
     82 
     83  private:
     84   // Current cached value of the property.
     85   T value_;
     86 
     87   // Replacement value of the property.
     88   T set_value_;
     89 };
     90 
     91 }  // namespace dbus_utils
     92 }  // namespace brillo
     93 
     94 #endif  // LIBBRILLO_BRILLO_DBUS_DBUS_PROPERTY_H_
     95