parse_version.cmake

# Copyright (C) 2020 Google, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# parse_version() reads and parses the version string from FILE, assigning the
# version string to ${PROJECT}_VERSION and the parsed version to
# ${PROJECT}_VERSION_MAJOR, ${PROJECT}_VERSION_MINOR, ${PROJECT}_VERSION_PATCH,
# and the optional ${PROJECT}_VERSION_FLAVOR.
#
# The version string take one of the forms:
#    <major>.<minor>.<patch>
#    <major>.<minor>.<patch>-<flavor>
function(parse_version FILE PROJECT)
    configure_file(${FILE} "${CMAKE_CURRENT_BINARY_DIR}/CHANGES.md") # Required to re-run cmake on version change
    file(READ ${FILE} CHANGES)
    if(${CHANGES} MATCHES "#+ *([0-9]+)\\.([0-9]+)\\.([0-9]+)(-[a-zA-Z0-9]+)?")
        set(FLAVOR "")
        if(NOT "${CMAKE_MATCH_4}" STREQUAL "")
            string(SUBSTRING ${CMAKE_MATCH_4} 1 -1 FLAVOR)
        endif()
        set("${PROJECT}_VERSION_MAJOR"  ${CMAKE_MATCH_1} PARENT_SCOPE)
        set("${PROJECT}_VERSION_MINOR"  ${CMAKE_MATCH_2} PARENT_SCOPE)
        set("${PROJECT}_VERSION_PATCH"  ${CMAKE_MATCH_3} PARENT_SCOPE)
        set("${PROJECT}_VERSION_FLAVOR" ${FLAVOR}        PARENT_SCOPE)
        set("${PROJECT}_VERSION"
            "${CMAKE_MATCH_1}.${CMAKE_MATCH_2}.${CMAKE_MATCH_3}${CMAKE_MATCH_4}"
            PARENT_SCOPE)
    else()
        message(FATAL_ERROR "Unable to parse version from '${FILE}'")
    endif()
endfunction()