cmake: West extension command for Zephyr config package registration

This command make it possible to use west for first time registration
of a Zephyr config package in CMake.

To register Zephyr as a CMake config package, invoke:
west zephyr-export

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

scripts/west-commands.yml

@@ -36,3 +36,8 @@ west-commands:
       - name: attach
         class: Attach
         help: interactively debug a board
+  - file: scripts/west_commands/export.py
+    commands:
+      - name: zephyr-export
+        class: ZephyrExport
+        help: export Zephyr installation as a CMake config package

scripts/west_commands/completion/west-completion.bash

@@ -770,6 +770,7 @@ __comp_west()
 		debug
 		debugserver
 		attach
+		zephyr-export
 	)
 
 	local cmds=(${builtin_cmds[*]} ${zephyr_ext_cmds[*]})

scripts/west_commands/export.py

@@ -0,0 +1,58 @@
+# Copyright (c) 2020 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+
+from west.commands import WestCommand
+
+from pathlib import PurePath
+from zcmake import run_cmake
+
+EXPORT_DESCRIPTION = '''\
+This command registers the current Zephyr installation as a CMake
+config package in the CMake user package registry.
+
+In Windows, the CMake user package registry is found in:
+HKEY_CURRENT_USER\\Software\\Kitware\\CMake\\Packages\\
+
+In Linux and MacOS, the CMake user package registry is found in:
+~/.cmake/packages/'''
+
+
+class ZephyrExport(WestCommand):
+
+    def __init__(self):
+        super().__init__(
+            'zephyr-export',
+            # Keep this in sync with the string in west-commands.yml.
+            'export Zephyr installation as a CMake config package',
+            EXPORT_DESCRIPTION,
+            accepts_unknown_args=False)
+
+    def do_add_parser(self, parser_adder):
+        parser = parser_adder.add_parser(
+            self.name,
+            help=self.help,
+            formatter_class=argparse.RawDescriptionHelpFormatter,
+            description=self.description)
+        return parser
+
+    def do_run(self, args, unknown_args):
+        zephyr_config_package_path = PurePath(__file__).parents[2] \
+            / 'share' / 'zephyr-package' / 'cmake'
+
+        cmake_args = ['-S', f'{zephyr_config_package_path}',
+                      '-B', f'{zephyr_config_package_path}']
+        lines = run_cmake(cmake_args, capture_output=True)
+
+        # Let's clean up, as Zephyr has now been exported, and we no longer
+	# need the generated files.
+        cmake_args = ['--build', f'{zephyr_config_package_path}',
+                      '--target', 'pristine']
+        run_cmake(cmake_args, capture_output=True)
+
+        # Let's ignore the normal CMake printing and instead only print
+        # the important information.
+        msg = [line for line in lines if not line.startswith('-- ')]
+        print('\n'.join(msg))

share/zephyr-package/cmake/CMakeLists.txt

@@ -25,5 +25,9 @@ else()
   message("~/.cmake/packages/ZephyrUnitTest")
 endif()
 
+add_custom_target(pristine
+                  COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_LIST_DIR}/pristine.cmake
+)
+
 export(PACKAGE Zephyr)
 export(PACKAGE ZephyrUnittest)

share/zephyr-package/cmake/pristine.cmake

@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: Apache-2.0
+
+# Purpose of this CMake file is to clean all CMake files generated by CMake when
+# exporting Zephry to CMake user package registry.
+
+# Get a list of all files.
+file(GLOB_RECURSE GENERATED_FILES
+     LIST_DIRECTORIES true
+     ${CMAKE_CURRENT_LIST_DIR}/*
+)
+
+# Remove the files that is used be Zephyr from the list.
+list(REMOVE_ITEM GENERATED_FILES
+     "${CMAKE_CURRENT_LIST_DIR}/CMakeLists.txt"
+     "${CMAKE_CURRENT_LIST_DIR}/pristine.cmake"
+     "${CMAKE_CURRENT_LIST_DIR}/zephyr_package_search.cmake"
+     "${CMAKE_CURRENT_LIST_DIR}/ZephyrConfigVersion.cmake"
+     "${CMAKE_CURRENT_LIST_DIR}/ZephyrUnittestConfigVersion.cmake"
+     "${CMAKE_CURRENT_LIST_DIR}/ZephyrConfig.cmake"
+     "${CMAKE_CURRENT_LIST_DIR}/ZephyrUnittestConfig.cmake"
+)
+
+# Delete everything else, as those files are created by CMake.
+file(REMOVE_RECURSE ${GENERATED_FILES})