Определение stream insertion оператора “<<” для объединения.

Author: gusenov

README.md

@@ -76,6 +76,7 @@
 - [Анонимное объединение внутри структуры с отслеживанием активного элемента](syncfusion/cpp_succinctly/UnionSample)
 - [Передача объединения в функцию](union/pass-union-to-function)
 - [Объединение указателей](union/union-of-ptr)
+- [Определение stream insertion оператора “<<” для объединения](union/union-and-stream-insertion-operator)
 
 ## Классы
 

union/union-and-stream-insertion-operator/.gitignore

@@ -0,0 +1,163 @@
+# ---------------------------------------------------------------------------
+# https://github.com/github/gitignore/blob/master/C++.gitignore
+
+# Prerequisites
+*.d
+
+# Compiled Object files
+*.slo
+*.lo
+*.o
+*.obj
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Compiled Dynamic libraries
+*.so
+*.dylib
+*.dll
+
+# Fortran module files
+*.mod
+*.smod
+
+# Compiled Static libraries
+*.lai
+*.la
+*.a
+*.lib
+
+# Executables
+*.exe
+*.out
+*.app
+
+# ---------------------------------------------------------------------------
+# https://github.com/github/gitignore/blob/master/Global/JetBrains.gitignore
+
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff
+.idea/**/workspace.xml
+.idea/**/tasks.xml
+.idea/**/usage.statistics.xml
+.idea/**/dictionaries
+.idea/**/shelf
+
+# AWS User-specific
+.idea/**/aws.xml
+
+# Generated files
+.idea/**/contentModel.xml
+
+# Sensitive or high-churn files
+.idea/**/dataSources/
+.idea/**/dataSources.ids
+.idea/**/dataSources.local.xml
+.idea/**/sqlDataSources.xml
+.idea/**/dynamic.xml
+.idea/**/uiDesigner.xml
+.idea/**/dbnavigator.xml
+
+# Gradle
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Gradle and Maven with auto-import
+# When using Gradle or Maven with auto-import, you should exclude module files,
+# since they will be recreated, and may cause churn.  Uncomment if using
+# auto-import.
+# .idea/artifacts
+# .idea/compiler.xml
+# .idea/jarRepositories.xml
+# .idea/modules.xml
+# .idea/*.iml
+# .idea/modules
+# *.iml
+# *.ipr
+
+# CMake
+cmake-build-*/
+
+# Mongo Explorer plugin
+.idea/**/mongoSettings.xml
+
+# File-based project format
+*.iws
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Cursive Clojure plugin
+.idea/replstate.xml
+
+# SonarLint plugin
+.idea/sonarlint/
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+# Editor-based Rest Client
+.idea/httpRequests
+
+# Android studio 3.1+ serialized cache file
+.idea/caches/build_file_checksums.ser
+
+# ---------------------------------------------------------------------------
+# https://github.com/github/gitignore/blob/master/Global/macOS.gitignore
+
+# General
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+# ---------------------------------------------------------------------------
+# https://github.com/github/gitignore/blob/master/CMake.gitignore
+
+CMakeLists.txt.user
+CMakeCache.txt
+CMakeFiles
+CMakeScripts
+Testing
+Makefile
+cmake_install.cmake
+install_manifest.txt
+compile_commands.json
+CTestTestfile.cmake
+_deps
+
+# ---------------------------------------------------------------------------

union/union-and-stream-insertion-operator/.idea/.gitignore

@@ -0,0 +1,6 @@
+cmake_minimum_required(VERSION 3.22)
+project(UnionAndStreamInsertionOperator)
+
+set(CMAKE_CXX_STANDARD 17)
+
+add_executable(${PROJECT_NAME} main.cpp foo.cpp)

union/union-and-stream-insertion-operator/.idea/.name

@@ -0,0 +1,47 @@
+#pragma once
+#include <type_traits>
+
+union _Vector3
+{
+    struct { float x, y, z; };
+
+    struct { float r, g, b; };
+
+    float v[3];
+
+    _Vector3(){v[0] = 0.0f; v[1] = 0.0f; v[2] = 0.0f;}
+
+    // Из-за этих двух конструкторов при выводе символа в std::stringstream получим ошибку компиляции:
+    // Use of overloaded operator '<<' is ambiguous (with operand types 'std::stringstream' (aka 'basic_stringstream<char>') and 'char')
+    _Vector3(int _v){v[0] = (float)_v; v[1] = (float)_v; v[2] = (float)_v;}
+    _Vector3(float _v){v[0] = _v; v[1] = _v; v[2] = _v;}
+
+    _Vector3(float x, float y, float z){v[0] = x; v[1] = y; v[2] = z;}
+};
+
+typedef union _Vector3 Vector3;
+
+static_assert(std::is_same_v<Vector3, _Vector3>);
+
+static_assert(!std::is_same_v<Vector3, float[]>);
+static_assert(!std::is_same_v<Vector3, float[3]>);
+static_assert(!std::is_same_v<Vector3, float*>);
+
+/*
+template<typename TOutputStream>
+TOutputStream& operator<<(TOutputStream& aOutputStream, Vector3 const& aVector3)
+{
+    aOutputStream << "(" << aVector3.x << ", " << aVector3.y << ", " << aVector3.z << ")";
+    return aOutputStream;
+}
+//*/
+
+//* FIX:
+template<typename TOutputStream, typename T>
+typename std::enable_if<std::is_same<T, Vector3>::value, TOutputStream&>::type
+operator<<(TOutputStream& aOutputStream, T const& aVector3)
+{
+    aOutputStream << "(" << aVector3.x << ", " << aVector3.y << ", " << aVector3.z << ")";
+    return aOutputStream;
+}
+//*/

union/union-and-stream-insertion-operator/.idea/misc.xml

@@ -0,0 +1,8 @@
+#include <iostream>
+#include "Vector3.h"
+
+void foo()
+{
+    Vector3 v;
+    std::cout << v;
+}

union/union-and-stream-insertion-operator/.idea/modules.xml

@@ -0,0 +1,23 @@
+#include <iostream>
+#include <string>
+#include <sstream>
+#include "Vector3.h"
+
+int main()
+{
+
+    std::string hello("Hello, World!");
+    std::stringstream strstream;
+    for (auto it = hello.begin(); it != hello.end(); ++it)
+        strstream << *it;
+    strstream << std::endl;
+    std::cout << strstream.str();
+
+    Vector3 v;
+    std::cout << v << std::endl;
+
+    float f = 2249.f;
+    std::cout << f << std::endl;
+
+    return 0;
+}