scripts: add list_boards.py

This script is essentially a Python rewrite of the CMake code we're
using to print boards in cmake/boards.cmake, plus some extra features.

Having this in Python will simplify some later adjustments to our
'usage' build system target in ways that will make its output easier
to read, while simultaneously making 'west boards' more useful.

Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>

CODEOWNERS

@@ -506,6 +506,7 @@
 /arch/x86/gen_idt.py                      @andrewboie
 /scripts/gen_kobject_list.py              @andrewboie
 /scripts/gen_syscalls.py                  @andrewboie
+/scripts/list_boards.py                   @mbolivar-nordic
 /scripts/net/                             @jukkar
 /scripts/process_gperf.py                 @andrewboie
 /scripts/gen_relocate_app.py              @wentongwu

scripts/list_boards.py

@@ -0,0 +1,113 @@
+#!/usr/bin/env python3
+
+# Copyright (c) 2020 Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+from collections import defaultdict
+import itertools
+from pathlib import Path
+from typing import NamedTuple
+
+ZEPHYR_BASE = Path(__file__).resolve().parents[1]
+
+#
+# This is shared code between the build system's 'boards' target
+# and the 'west boards' extension command. If you change it, make
+# sure to test both ways it can be used.
+#
+# (It's done this way to keep west optional, making it possible to run
+# 'ninja boards' in a build directory without west installed.)
+#
+
+class Board(NamedTuple):
+    name: str
+    arch: str
+    dir: Path
+
+def board_key(board):
+    return board.name
+
+def find_arch2boards(args):
+    arch2board_set = find_arch2board_set(args)
+    return {arch: sorted(arch2board_set[arch], key=board_key)
+            for arch in arch2board_set}
+
+def find_boards(args):
+    return sorted(itertools.chain(*find_arch2board_set(args).values()),
+                  key=board_key)
+
+def find_arch2board_set(args):
+    arches = sorted(find_arches(args))
+    ret = defaultdict(set)
+
+    for root in itertools.chain([ZEPHYR_BASE], args.board_roots):
+        for arch, boards in find_arch2board_set_in(root, arches).items():
+            ret[arch] |= boards
+
+    return ret
+
+def find_arches(args):
+    arch_set = find_arches_in(ZEPHYR_BASE)
+
+    for root in args.arch_roots:
+        arch_set |= find_arches_in(root)
+
+    return arch_set
+
+def find_arches_in(root):
+    ret = set()
+    arch = root / 'arch'
+    common = arch / 'common'
+
+    if not arch.is_dir():
+        return ret
+
+    for maybe_arch in arch.iterdir():
+        if not maybe_arch.is_dir() or maybe_arch == common:
+            continue
+        ret.add(maybe_arch.name)
+
+    return ret
+
+def find_arch2board_set_in(root, arches):
+    ret = defaultdict(set)
+    boards = root / 'boards'
+
+    for arch in arches:
+        for maybe_board in (boards / arch).iterdir():
+            if not maybe_board.is_dir():
+                continue
+            for maybe_defconfig in maybe_board.iterdir():
+                file_name = maybe_defconfig.name
+                if file_name.endswith('_defconfig'):
+                    board_name = file_name[:-len('_defconfig')]
+                    ret[arch].add(Board(board_name, arch, maybe_board))
+
+    return ret
+
+def parse_args():
+    parser = argparse.ArgumentParser()
+    add_args(parser)
+    return parser.parse_args()
+
+def add_args(parser):
+    # Remember to update west-completion.bash if you add or remove
+    # flags
+    parser.add_argument("--arch-root", dest='arch_roots', default=[],
+                        type=Path, action='append',
+                        help='''add an architecture root (ZEPHYR_BASE is
+                        always present), may be given more than once''')
+    parser.add_argument("--board-root", dest='board_roots', default=[],
+                        type=Path, action='append',
+                        help='''add a board root (ZEPHYR_BASE is always
+                        present), may be given more than once''')
+
+def dump_boards(arch2boards):
+    for arch, boards in arch2boards.items():
+        print(f'{arch}:')
+        for board in boards:
+            print(f'  {board.name}')
+
+if __name__ == '__main__':
+    dump_boards(find_arch2boards(parse_args()))