Initial implementation

colcon_top_level_workspace/argument_parser/top_level_workspace.py

@@ -0,0 +1,108 @@
+# Copyright 2023 Scott K Logan
+# Licensed under the Apache License, Version 2.0
+
+import os
+from pathlib import Path
+
+from colcon_core.argument_parser import ArgumentParserDecoratorExtensionPoint
+from colcon_core.argument_parser import SuppressUsageOutput
+from colcon_core.argument_parser.action_collector \
+    import ActionCollectorDecorator
+from colcon_core.argument_parser.action_collector \
+    import SuppressRequiredActions
+from colcon_core.argument_parser.action_collector \
+    import SuppressTypeConversions
+from colcon_core.plugin_system import satisfies_version
+
+
+class TopLevelWorkspaceArgumentParserDecorator(
+    ArgumentParserDecoratorExtensionPoint
+):
+    """Locate and use a top-level workspace from a subdirectory."""
+
+    # Lower priority to appear as close to time-of-use as possible
+    PRIORITY = 75
+
+    def __init__(self):  # noqa: D107
+        super().__init__()
+        satisfies_version(
+            ArgumentParserDecoratorExtensionPoint.EXTENSION_POINT_VERSION,
+            '^1.0')
+
+    def decorate_argument_parser(self, *, parser):  # noqa: D102
+        return TopLevelWorkspaceArgumentDecorator(parser)
+
+
+def _enumerate_parsers(parser):
+    yield from parser._parsers
+    for subparser in parser._subparsers:
+        for p in subparser._parsers:
+            yield p
+            yield from _enumerate_parsers(p)
+
+
+class TopLevelWorkspaceArgumentDecorator(ActionCollectorDecorator):
+    """Change to a top-level workspace if one is found."""
+
+    def __init__(self, parser):  # noqa: D107
+        # avoid setting members directly, the base class overrides __setattr__
+        # pass them as keyword arguments instead
+        super().__init__(
+            parser,
+            _parsers=[],
+            _subparsers=[])
+
+    def add_parser(self, *args, **kwargs):
+        """Collect association of parsers to their name."""
+        parser = super().add_parser(*args, **kwargs)
+        self._parsers.append(parser)
+        return parser
+
+    def add_subparsers(self, *args, **kwargs):
+        """Collect all subparsers."""
+        subparser = super().add_subparsers(*args, **kwargs)
+        self._subparsers.append(subparser)
+        return subparser
+
+    def parse_args(self, *args, **kwargs):  # noqa: D102
+        parsers = [self._parser]
+        parsers.extend(_enumerate_parsers(self))
+        with SuppressUsageOutput(parsers):
+            with SuppressTypeConversions(parsers):
+                with SuppressRequiredActions(parsers):
+                    known_args, _ = self._parser.parse_known_args(
+                        *args, **kwargs)
+
+        base = 'build'
+        for arg in ('build_base', 'test_result_base'):
+            if hasattr(known_args, arg):
+                base = getattr(known_args, arg)
+                break
+        if not os.path.isabs(base):
+            cwd = Path.cwd()
+            workspace = find_top_level_workspace(cwd, base)
+            if workspace and workspace != cwd:
+                print(f"Using top-level workspace at '{workspace}'")
+                os.chdir(str(workspace))
+        args = self._parser.parse_args(*args, **kwargs)
+        return args
+
+
+def find_top_level_workspace(candidate, base, this_build_tool='colcon'):
+    """
+    Search for an existing top-level colcon workspace.
+
+    :param candidate: Directory at which the search should begin
+    :param str base: The base directory
+    :param str this_build_tool: The name of this build tool
+
+    :returns: Path to an existing workspace root, or None
+    """
+    marker = candidate / base / '.built_by'
+    if marker.is_file():
+        if marker.read_text().rstrip() == this_build_tool:
+            return candidate
+    if candidate.parent != candidate:
+        return find_top_level_workspace(
+            candidate.parent, base, this_build_tool)
+    return None

setup.cfg

@@ -24,7 +24,7 @@ keywords = colcon
 [options]
 python_requires = >=3.6
 install_requires =
-  colcon-core
+  colcon-core>=0.13.0
 packages = find:
 zip_safe = true
 
@@ -49,6 +49,8 @@ test =
 junit_suite_name = colcon-top-level-workspace
 
 [options.entry_points]
+colcon_core.argument_parser =
+    top_level_workspace = colcon_top_level_workspace.argument_parser.top_level_workspace:TopLevelWorkspaceArgumentParserDecorator
 
 [flake8]
 import-order-style = google

stdeb.cfg

@@ -1,5 +1,5 @@
 [colcon-top-level-workspace]
 No-Python2:
-Depends3: python3-colcon-core
+Depends3: python3-colcon-core (>= 0.13.0)
 Suite: bionic focal jammy stretch buster bullseye
 X-Python3-Version: >= 3.6

test/spell_check.words

@@ -1,8 +1,15 @@
 apache
+chdir
 colcon
 iterdir
+noqa
 pathlib
+plugin
 pytest
+rstrip
+scott
 scspell
 setuptools
+subparser
+subparsers
 thomas