From 9478da10c608506869f8007f9bf8a356525e6bb4 Mon Sep 17 00:00:00 2001
From: "Watal M. Iwasaki" <heavywatal@users.noreply.github.com>
Date: Tue, 28 May 2024 13:53:11 +0900
Subject: [PATCH] :art: Replace git submodules with CMake FetchContent

---
 .github/workflows/build.yaml | 14 +++++--------
 .gitmodules                  |  6 ------
 CMakeLists.txt               | 40 +++++++++++++++++++++++++++++++++---
 README.md                    |  1 -
 clipp                        |  1 -
 json                         |  1 -
 6 files changed, 42 insertions(+), 21 deletions(-)
 delete mode 160000 clipp
 delete mode 160000 json

diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index cd246ff..f50ee07 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -1,12 +1,10 @@
-name: build
-
 on:
   push:
-    branches:
-      - master
+    branches: [main, master]
   pull_request:
-    branches:
-      - master
+    branches: [main, master]
+
+name: build
 
 jobs:
   build:
@@ -17,13 +15,11 @@ jobs:
         os: [macOS-latest, ubuntu-latest]
     steps:
       - uses: actions/checkout@v4
-        with:
-          submodules: true
       - name: cmake
         run: cmake -S . -B build -DCMAKE_INSTALL_PREFIX=${HOME}/local
       - name: build
         run: |
-          cmake --build build -j2
+          cmake --build build -j 2
           cmake --install build
       - name: test
         run: cd build; ctest -V -j 2
diff --git a/.gitmodules b/.gitmodules
index ff26c10..e69de29 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +0,0 @@
-[submodule "clipp"]
-	path = clipp
-	url = https://github.com/heavywatal/clipp.git
-[submodule "json"]
-	path = json
-	url = https://github.com/heavywatal/json.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 74da747..cf0284e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,15 +3,49 @@ project(clippson
   VERSION 0.8.6
   LANGUAGES CXX)
 
+cmake_policy(SET CMP0076 NEW)
 set(CMAKE_VERBOSE_MAKEFILE ON)
 include(CMakePrintHelpers)
+include(FetchContent)
 include(GNUInstallDirs)
 cmake_print_variables(CMAKE_INSTALL_PREFIX)
 
+function(import_env variable)
+  if(DEFINED ENV{${variable}})
+    set(${variable} $ENV{${variable}} PARENT_SCOPE)
+  endif()
+endfunction()
+
+function(git_fetch package version repo)
+  string(TOUPPER "${package}" upackage)
+  import_env("FETCHCONTENT_SOURCE_DIR_${upackage}")
+  if(IS_DIRECTORY "${FETCHCONTENT_SOURCE_DIR_${upackage}}")
+    set(tag "HEAD")
+  else()
+    set(tag "${version}")
+  endif()
+  cmake_print_variables(FETCHCONTENT_SOURCE_DIR_${upackage} tag)
+  set(FETCHCONTENT_QUIET OFF)
+  FetchContent_Declare(
+    ${package}
+    GIT_REPOSITORY https://github.com/${repo}.git
+    GIT_TAG ${tag}
+    GIT_SHALLOW ON
+  )
+  if(NOT ${package}_POPULATED)
+    FetchContent_Populate(${package})
+  endif()
+  set(${package}_SOURCE_DIR ${${package}_SOURCE_DIR} PARENT_SCOPE)
+  cmake_print_variables(${package}_SOURCE_DIR)
+endfunction()
+
+git_fetch(clipp v1.2.3.1 heavywatal/clipp)
+git_fetch(json v3.11.3 heavywatal/json)
+
 set(subrepo_files
-  clipp/include/clipp.h
-  json/src/json.hpp
-  json/src/json_fwd.hpp
+  ${clipp_SOURCE_DIR}/include/clipp.h
+  ${json_SOURCE_DIR}/src/json.hpp
+  ${json_SOURCE_DIR}/src/json_fwd.hpp
 )
 foreach(file IN LISTS subrepo_files)
   configure_file(${file} ${PROJECT_SOURCE_DIR}/include/${PROJECT_NAME}/ COPYONLY)
diff --git a/README.md b/README.md
index c2b6137..bd46b86 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,6 @@ Alternatively, you can get the source code from GitHub manually:
 ```sh
 git clone https://github.com/heavywatal/clippson.git
 cd clippson/
-git submodule update --init --recursive
 DESTINATION=${HOME}/local
 cmake -S . -B build -DCMAKE_INSTALL_PREFIX=$DESTINATION
 cmake --build build -j2
diff --git a/clipp b/clipp
deleted file mode 160000
index bc8045f..0000000
--- a/clipp
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit bc8045f9daf0031f169da3485b331a7cdb3ea473
diff --git a/json b/json
deleted file mode 160000
index 3a65cd7..0000000
--- a/json
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 3a65cd7687a9f99ae0a2e1c74e35e6d72fee8f45