Add example of visitor pattern in C++

cpp/patterns/visitor/CMakeLists.txt

@@ -0,0 +1,20 @@
+###############################################################################
+## Author: Shaun Reed                                                        ##
+## Legal: All Content (c) 2021 Shaun Reed, all rights reserved               ##
+## About: A project for practicing the visitor C++ design pattern            ##
+##                                                                           ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0  ##
+##############################################################################
+#
+cmake_minimum_required(VERSION 3.15)
+project(
+    #[[NAME]]   Visitor
+    VERSION     1.0
+    DESCRIPTION "An example of the visitor design pattern in C++"
+    LANGUAGES   CXX
+)
+add_compile_options("-Wall")
+
+add_library(visitor "visitor.cpp")
+add_executable(visitor-test "main.cpp")
+target_link_libraries(visitor-test visitor)