Add BoostFetch.cmake

cmake/BoostFetch.cmake

@@ -0,0 +1,80 @@
+# Copyright 2018 Peter Dimov
+# Distributed under the Boost Software License, Version 1.0.
+# See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt
+
+if(NOT COMMAND FetchContent_Populate)
+
+    if(CMAKE_VERSION VERSION_LESS 3.11)
+
+        message(STATUS "Fetching FetchContent.cmake")
+
+        file(DOWNLOAD
+            "https://gitlab.kitware.com/cmake/cmake/raw/v3.11.3/Modules/FetchContent.cmake"
+            "${CMAKE_BINARY_DIR}/Modules/FetchContent.cmake"
+        )
+
+        file(DOWNLOAD
+            "https://gitlab.kitware.com/cmake/cmake/raw/v3.11.3/Modules/FetchContent/CMakeLists.cmake.in"
+            "${CMAKE_BINARY_DIR}/Modules/FetchContent/CMakeLists.cmake.in"
+        )
+
+        include(${CMAKE_BINARY_DIR}/Modules/FetchContent.cmake)
+
+    else()
+
+        include(FetchContent)
+
+    endif()
+
+endif()
+
+function(boost_fetch)
+
+    cmake_parse_arguments(_ "" "TAG" "" ${ARGN})
+
+    if(NOT __UNPARSED_ARGUMENTS)
+
+        message(FATAL_ERROR "boost_fetch: missing required argument, repository name")
+        return()
+
+    endif()
+
+    list(GET __UNPARSED_ARGUMENTS 0 REPO)
+    list(REMOVE_AT __UNPARSED_ARGUMENTS 0)
+
+    if(__UNPARSED_ARGUMENTS)
+
+        message(WARNING "boost_fetch: extra arguments ignored: ${__UNPARSED_ARGUMENTS}")
+
+    endif()
+
+    if(NOT __TAG)
+
+        set(__TAG master)
+
+    endif()
+
+    string(MAKE_C_IDENTIFIER ${REPO} NAME)
+
+    if(CMAKE_VERSION VERSION_LESS 3.6)
+
+        FetchContent_Declare(${NAME} QUIET GIT_REPOSITORY "https://github.com/${REPO}" GIT_TAG ${__TAG})
+
+    else()
+
+        FetchContent_Declare(${NAME} QUIET GIT_REPOSITORY "https://github.com/${REPO}" GIT_TAG ${__TAG} GIT_SHALLOW 1)
+
+    endif()
+
+    FetchContent_GetProperties(${NAME})
+
+    if(NOT ${NAME}_POPULATED)
+
+        message(STATUS "Fetching ${REPO}:${__TAG}")
+
+        FetchContent_Populate(${NAME})
+        add_subdirectory(${${NAME}_SOURCE_DIR} ${${NAME}_BINARY_DIR})
+
+    endif()
+
+endfunction(boost_fetch)