From 964438dfb79b521c1a1ffd17c311ed2f797f5954 Mon Sep 17 00:00:00 2001
From: Kenneth Benzie <k.benzie83@gmail.com>
Date: Fri, 8 Jun 2018 11:46:44 +0100
Subject: [PATCH] Play nice with CMake add_subdirectory (#25)

Enable use of `tl::expected<T, E>` purely as a library with CMake's
`add_subdirectory`. The default configuration works are before.

* `EXPECTED_ENABLE_TESTS` make building tests optional, enabled by default
* `EXPECTED_ENABLE_DOCS` make building documentation optional, enabled by default
---
 CMakeLists.txt | 62 +++++++++++++++++++++++++++-----------------------
 1 file changed, 34 insertions(+), 28 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8ad070d..0951b1e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,40 +2,46 @@ cmake_minimum_required(VERSION 3.0)
 
 project(expected)
 
+option(EXPECTED_ENABLE_TESTS "Enable tests." ON)
+option(EXPECTED_ENABLE_DOCS "Enable documentation." ON)
+
+add_library(expected INTERFACE)
+target_sources(expected INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/tl/expected.hpp)
+target_include_directories(expected INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/tl)
+
 # Prepare "Catch" library for other executables
-set(CATCH_INCLUDE_DIR ${CMAKE_SOURCE_DIR}/test)
+set(CATCH_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/test)
 add_library(Catch INTERFACE)
 target_include_directories(Catch INTERFACE ${CATCH_INCLUDE_DIR})
 
-# Make test executable
-set(TEST_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/tests/main.cpp
-                 ${CMAKE_CURRENT_SOURCE_DIR}/tests/extensions.cpp
-                 ${CMAKE_CURRENT_SOURCE_DIR}/tests/assignment.cpp
-                 ${CMAKE_CURRENT_SOURCE_DIR}/tests/emplace.cpp
-                 ${CMAKE_CURRENT_SOURCE_DIR}/tests/issues.cpp
-                 ${CMAKE_CURRENT_SOURCE_DIR}/tests/bases.cpp
-                 ${CMAKE_CURRENT_SOURCE_DIR}/tests/observers.cpp
-                 ${CMAKE_CURRENT_SOURCE_DIR}/tests/constructors.cpp)
+if(EXPECTED_ENABLE_TESTS)
+  # Make test executable
+  set(TEST_SOURCES ${CMAKE_CURRENT_SOURCE_DIR}/tests/main.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/extensions.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/assignment.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/emplace.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/issues.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/bases.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/observers.cpp
+                   ${CMAKE_CURRENT_SOURCE_DIR}/tests/constructors.cpp)
 
-add_executable(tests ${TEST_SOURCES})
+  add_executable(tests ${TEST_SOURCES})
 
-add_library(expected INTERFACE)
-target_sources(expected INTERFACE ${CMAKE_SOURCE_DIR}/tl/expected.hpp)
-target_include_directories(expected INTERFACE ${CMAKE_SOURCE_DIR}/tl)
+  target_link_libraries(tests Catch expected)
 
-target_link_libraries(tests Catch expected)
+  set(CXXSTD 14 CACHE STRING "C++ standard to use, default C++14")
+  set_property(TARGET tests PROPERTY CXX_STANDARD ${CXXSTD})
+  set_property(TARGET tests PROPERTY CXX_FLAGS "-Wall -Wextra")
+endif()
 
-set(CXXSTD 14 CACHE STRING "C++ standard to use, default C++14")
-set_property(TARGET tests PROPERTY CXX_STANDARD ${CXXSTD})
-set_property(TARGET tests PROPERTY CXX_FLAGS "-Wall -Wextra")
+if(EXPECTED_ENABLE_DOCS)
+  find_package(standardese) # find standardese after installation
 
-
-find_package(standardese) # find standardese after installation
-
-# generates a custom target that will run standardese to generate the documentation
-if (standardese_FOUND)
-standardese_generate(expected
-                     INCLUDE_DIRECTORY tl
-                     CONFIG ${CMAKE_SOURCE_DIR}/standardese.config
-                     INPUT tl/expected.hpp)
-endif ()
+  # generates a custom target that will run standardese to generate the documentation
+  if(standardese_FOUND)
+    standardese_generate(expected
+                         INCLUDE_DIRECTORY tl
+                         CONFIG ${CMAKE_CURRENT_SOURCE_DIR}/standardese.config
+                         INPUT tl/expected.hpp)
+  endif()
+endif()