doc/common/extensions: Add requirements directive.

Displays compatibility for each hub depending on its features.

doc/common/conf.py

@@ -60,6 +60,7 @@ extensions = [
     'sphinx.ext.mathjax',
     'color',
     'classlink',
+    'requirements',
 ]
 
 # Add any paths that contain templates here, relative to this directory.

doc/common/extensions/requirements.py

@@ -0,0 +1,79 @@
+from docutils import nodes
+from docutils.parsers.rst import Directive
+
+
+# Base feature set.
+FEATURES_SMALL = set()
+
+# Medium feature set.
+FEATURES_MEDIUM = FEATURES_SMALL | {
+    'pybricks-geometry',
+    'pybricks-iodevices',
+    'stm32-extra',
+    'stm32-float',
+}
+
+# Large feature set.
+FEATURES_LARGE = FEATURES_MEDIUM | set()
+
+# Features per hub.
+HUB_FEATURES = {
+    'movehub': FEATURES_SMALL,
+    'cityhub': FEATURES_MEDIUM,
+    'technichub': FEATURES_MEDIUM,
+    'primehub': FEATURES_LARGE,
+    'inventorhub': FEATURES_LARGE,
+}
+
+
+class PybricksRequirementsDirective(Directive):
+
+    required_arguments = 1
+    optional_arguments = 10
+
+    def run(self):
+        # Get requirements from sphinx-directive.
+        requirements = set(self.arguments)
+
+        # Check compatibility for all hubs.
+        compatible = {
+            hub: requirements <= features
+            for hub, features in HUB_FEATURES.items()
+        }
+
+        # Table cells with hub images.
+        hub_cells = ["<th>{0}</th>".format(hub) for hub in compatible]
+
+        # Table cells with checkmark or cross.
+        compat_cells = [
+            "<td>✔️</td>" if compat else "<td>❌</td>"
+            for hub, compat in compatible.items()
+        ]
+
+        # Generate full table.
+        html = """
+        <table>
+            <thead>
+            <tr>
+                {0}
+            </tr>
+            </thead>
+            <tbody>
+            <tr>
+                {1}
+            </tr>
+            </tbody>
+        </table>
+        """.format("".join(hub_cells), "".join(compat_cells))
+
+        # Return the node.
+        node = nodes.raw('', html, format="html")
+        return [node]
+
+
+def setup(app):
+    app.add_directive_to_domain(
+        'py',
+        'pybricks-requirements',
+        PybricksRequirementsDirective
+    )

doc/main/micropython/umath.rst

@@ -1,8 +1,7 @@
 :mod:`umath <umath>` -- Math functions
 ============================================================
 
-This module is available on the the City Hub, Technic Hub,
-Prime Hub, and Inventor Hub.
+.. pybricks-requirements:: stm32-extra stm32-float
 
 This MicroPython module is similar to the `math module`_ in Python.