Fetch content (#593)

* Add git_archival mechanism

* fetch_content

* Delete .pre-commit-config.yaml

* Update CPM.cmake

* cmake-format

Author: flagarde

.git_archival.txt

@@ -0,0 +1,3 @@
+node: $Format:%H$
+node-date: $Format:%cI$
+describe-name: $Format:%(describe:tags=true,match=?[0-9.]*)$

.gitattributes

@@ -0,0 +1 @@
+.git_archival.txt  export-subst

CMakeLists.txt

@@ -0,0 +1,28 @@
+cmake_minimum_required(VERSION 3.14 FATAL_ERROR)
+
+if(EXISTS "${CMAKE_CURRENT_SOURCE_DIR}/.git/")
+  find_package(Git REQUIRED)
+  execute_process(
+    COMMAND "${GIT_EXECUTABLE}" describe --tags --match=?[0-9.]*
+    WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+    OUTPUT_VARIABLE DESCRIBE_NAME COMMAND_ERROR_IS_FATAL ANY
+  )
+  set(CPM_DEVELOPMENT "-development-version")
+else()
+  file(STRINGS "${CMAKE_CURRENT_SOURCE_DIR}/.git_archival.txt" DESCRIBE_NAME
+       REGEX "^describe-name:.*"
+  )
+endif()
+
+string(REGEX MATCH "([0-9\\.]+)" EXTRACTED_CPM_VERSION "${DESCRIBE_NAME}")
+
+project(
+  CPM.cmake
+  VERSION "${EXTRACTED_CPM_VERSION}"
+  DESCRIPTION
+    "CMake's missing package manager. A small CMake script for setup-free, cross-platform, reproducible dependency management."
+  HOMEPAGE_URL "https://github.com/cpm-cmake/CPM.cmake"
+  LANGUAGES NONE
+)
+
+include("${CMAKE_CURRENT_SOURCE_DIR}/cmake/CPM.cmake")

cmake/CPM.cmake

@@ -42,7 +42,11 @@ if(NOT COMMAND cpm_message)
   endfunction()
 endif()
 
-set(CURRENT_CPM_VERSION 1.0.0-development-version)
+if(DEFINED EXTRACTED_CPM_VERSION)
+  set(CURRENT_CPM_VERSION "${EXTRACTED_CPM_VERSION}${CPM_DEVELOPMENT}")
+else()
+  set(CURRENT_CPM_VERSION 1.0.0-development-version)
+endif()
 
 get_filename_component(CPM_CURRENT_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}" REALPATH)
 if(CPM_DIRECTORY)