Return reference from iterator (#40)

Fixes blocking iterator by returning (const) reference type from the dereference operator.

Author: andreiavrammsd

.vscode/settings.json

@@ -4,7 +4,7 @@
         "-Dcpp_channel_build_tests=ON"
     ],
     "editor.codeActionsOnSave": {
-        "source.fixAll": true
+        "source.fixAll": "explicit"
     },
     "editor.formatOnSave": true,
     "clang-format.executable": "clang-format",

CMakeLists.txt

@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.12)
 project(cpp_channel)
-set(PROJECT_VERSION 0.8.2)
+set(PROJECT_VERSION 0.8.3)
 
 set(CMAKE_CXX_STANDARD 11)
 set(CMAKE_CXX_STANDARD_REQUIRED YES)

examples/cmake-project/CMakeLists.txt

@@ -14,7 +14,7 @@ target_link_libraries(cmake_project)
 
 include(FetchContent)
 if (NOT channel_POPULATED)
-    FetchContent_Declare(channel URL https://github.com/andreiavrammsd/cpp-channel/archive/v0.8.1.zip)
+    FetchContent_Declare(channel URL https://github.com/andreiavrammsd/cpp-channel/archive/v0.8.3.zip)
     FetchContent_Populate(channel)
     include_directories(${channel_SOURCE_DIR}/include)
     # OR

include/msd/blocking_iterator.hpp

@@ -20,9 +20,9 @@ template <typename Channel>
 class blocking_iterator {
    public:
     using value_type = typename Channel::value_type;
-    using reference = typename Channel::value_type&;
+    using reference = const typename Channel::value_type&;
 
-    explicit blocking_iterator(Channel& ch) : ch_{ch} {}
+    explicit blocking_iterator(Channel& chan) : chan_{chan} {}
 
     /**
      * Advances to next element in the channel.
@@ -32,39 +32,39 @@ class blocking_iterator {
     /**
      * Returns an element from the channel.
      */
-    value_type operator*() const
+    reference operator*()
     {
-        value_type value{};
-        ch_ >> value;
+        chan_ >> value_;
 
-        return value;
+        return value_;
     }
 
     /**
      * Makes iteration continue until the channel is closed and empty.
      */
     bool operator!=(blocking_iterator<Channel>) const
     {
-        std::unique_lock<std::mutex> lock{ch_.mtx_};
-        ch_.waitBeforeRead(lock);
+        std::unique_lock<std::mutex> lock{chan_.mtx_};
+        chan_.waitBeforeRead(lock);
 
-        return !(ch_.closed() && ch_.empty());
+        return !(chan_.closed() && chan_.empty());
     }
 
    private:
-    Channel& ch_;
+    Channel& chan_;
+    value_type value_{};
 };
 
 }  // namespace msd
 
 /**
- * @brief Output iterator specialization
+ * @brief Input iterator specialization
  */
 template <typename T>
 struct std::iterator_traits<msd::blocking_iterator<T>> {
     using value_type = typename msd::blocking_iterator<T>::value_type;
     using reference = typename msd::blocking_iterator<T>::reference;
-    using iterator_category = std::output_iterator_tag;
+    using iterator_category = std::input_iterator_tag;
 };
 
 #endif  // MSD_CHANNEL_BLOCKING_ITERATOR_HPP_

tests/blocking_iterator_test.cpp

@@ -12,7 +12,7 @@ TEST(ChannelIteratorTest, Traits)
 
     using iterator_traits = std::iterator_traits<iterator>;
     EXPECT_TRUE((std::is_same<iterator_traits::value_type, type>::value));
-    EXPECT_TRUE((std::is_same<iterator_traits::iterator_category, std::output_iterator_tag>::value));
+    EXPECT_TRUE((std::is_same<iterator_traits::iterator_category, std::input_iterator_tag>::value));
 }
 
 TEST(ChannelIteratorTest, Dereference)