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      1 /*
      2  * Copyright 2014 Google Inc. All rights reserved.
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <fruit/fruit.h>
     18 #include <iostream>
     19 
     20 using fruit::Component;
     21 using fruit::Injector;
     22 
     23 class Listener {
     24 public:
     25   virtual void notify() = 0;
     26 };
     27 
     28 class Listener1 : public Listener {
     29 public:
     30   INJECT(Listener1()) = default;
     31 
     32   void notify() override {
     33     std::cout << "Listener 1 notified" << std::endl;
     34   }
     35 };
     36 
     37 class Writer {
     38 public:
     39   virtual void write(std::string s) = 0;
     40 };
     41 
     42 // To show that we can inject parameters of multibindings
     43 class StdoutWriter : public Writer {
     44 public:
     45   INJECT(StdoutWriter()) = default;
     46 
     47   void write(std::string s) override {
     48     std::cout << s << std::endl;
     49   }
     50 };
     51 
     52 class Listener2 : public Listener {
     53 private:
     54   Writer* writer;
     55 
     56 public:
     57   INJECT(Listener2(Writer* writer)) : writer(writer) {}
     58 
     59   void notify() override {
     60     writer->write("Listener 2 notified");
     61   }
     62 };
     63 
     64 Component<> getListenersComponent() {
     65   // Here they are in the same component to keep it simple, but Fruit collects all multibindings in installed
     66   // components.
     67   return fruit::createComponent()
     68       .bind<Writer, StdoutWriter>()
     69       .addMultibinding<Listener, Listener1>()
     70       .addMultibinding<Listener, Listener2>();
     71 }
     72 
     73 int main() {
     74   Injector<> injector(getListenersComponent);
     75   std::vector<Listener*> listeners = injector.getMultibindings<Listener>();
     76 
     77   // The order of the returned listeners is unspecified, so the lines in output may have any order.
     78   for (Listener* listener : listeners) {
     79     listener->notify();
     80   }
     81 
     82   return 0;
     83 }
     84