Add sphinx integration

Add a restructuredtext directive for documenting a set of plugins with
the needed hooks to make it available is sphinx.

Change-Id: I1a24f9326b4e54174d9dc0ae366315fe29c3ac1b

5 files changed, 303 insertions, 0 deletions

diff --git a/doc/source/conf.py b/doc/source/conf.py
index 16f953e..c606daa 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -32,6 +32,7 @@ extensions = [
     'sphinx.ext.graphviz',
     'sphinx.ext.extlinks',
     'oslosphinx',
+    'stevedore.sphinxext',
 ]
 
 # Add any paths that contain templates here, relative to this directory.
diff --git a/doc/source/index.rst b/doc/source/index.rst
index 884c014..9fa9548 100644
--- a/doc/source/index.rst
+++ b/doc/source/index.rst
@@ -21,6 +21,7 @@ Contents:
    patterns_enabling
    tutorial/index
    managers
+   sphinxext
    install
    essays/*
    history
diff --git a/doc/source/sphinxext.rst b/doc/source/sphinxext.rst
new file mode 100644
index 0000000..99f5ea3
--- /dev/null
+++ b/doc/source/sphinxext.rst
@@ -0,0 +1,73 @@
+====================
+ Sphinx Integration
+====================
+
+Stevedore includes an extension for integrating with Sphinx to
+automatically produce documentation about the supported plugins. To
+activate the plugin add ``stevedore.sphinxext`` to the list of
+extensions in your ``conf.py``.
+
+.. rst:directive:: .. list-plugins:: namespace
+
+   List the plugins in a namespace.
+
+   Options:
+
+   ``detailed``
+      Flag to switch between simple and detailed output (see
+      below).
+   ``overline-style``
+      Character to use to draw line above header,
+      defaults to none.
+   ``underline-style``
+      Character to use to draw line below header,
+      defaults to ``=``.
+
+Simple List
+===========
+
+By default, the ``list-plugins`` directive produces a simple list of
+plugins in a given namespace including the name and the first line of
+the docstring. For example:
+
+::
+
+  .. list-plugins:: stevedore.example.formatter
+
+produces
+
+------
+
+.. list-plugins:: stevedore.example.formatter
+
+------
+
+Detailed Lists
+==============
+
+Adding the ``detailed`` flag to the directive causes the output to
+include a separate subsection for each plugin, with the full docstring
+rendered. The section heading level can be controlled using the
+``underline-style`` and ``overline-style`` options to fit the results
+into the structure of your existing document.
+
+::
+
+  .. list-plugins:: stevedore.example.formatter
+     :detailed:
+
+produces
+
+------
+
+.. list-plugins:: stevedore.example.formatter
+   :detailed:
+   :underline-style: -
+
+------
+
+.. note::
+
+   Depending on how Sphinx is configured, bad reStructuredText syntax in
+   the docstrings of the plugins may cause the documentation build to
+   fail completely when detailed mode is enabled.
diff --git a/stevedore/sphinxext.py b/stevedore/sphinxext.py
new file mode 100644
index 0000000..524f9c9
--- /dev/null
+++ b/stevedore/sphinxext.py
@@ -0,0 +1,108 @@
+#    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
+#
+#         http://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.
+
+from __future__ import unicode_literals
+
+import inspect
+
+from docutils import nodes
+from docutils.parsers import rst
+from docutils.parsers.rst import directives
+from docutils.statemachine import ViewList
+from sphinx.util.nodes import nested_parse_with_titles
+
+from stevedore import extension
+
+
+def _get_docstring(plugin):
+    return inspect.getdoc(plugin) or ''
+
+
+def _simple_list(mgr):
+    for name in sorted(mgr.names()):
+        ext = mgr[name]
+        doc = _get_docstring(ext.plugin) or '\n'
+        summary = doc.splitlines()[0].strip()
+        yield('* %s -- %s' % (ext.name, summary),
+              ext.entry_point.module_name)
+
+
+def _detailed_list(mgr, over='', under='-'):
+    for name in sorted(mgr.names()):
+        ext = mgr[name]
+        if over:
+            yield (over * len(ext.name), ext.entry_point.module_name)
+        yield (ext.name, ext.entry_point.module_name)
+        if under:
+            yield (under * len(ext.name), ext.entry_point.module_name)
+        yield ('\n', ext.entry_point.module_name)
+        doc = _get_docstring(ext.plugin)
+        if doc:
+            yield (doc, ext.entry_point.module_name)
+        else:
+            yield ('.. warning:: No documentation found in %s'
+                   % ext.entry_point,
+                   ext.entry_point.module_name)
+        yield ('\n', ext.entry_point.module_name)
+
+
+class ListPluginsDirective(rst.Directive):
+    """Present a simple list of the plugins in a namespace."""
+
+    option_spec = {
+        'class': directives.class_option,
+        'detailed': directives.flag,
+        'overline-style': directives.single_char_or_unicode,
+        'underline-style': directives.single_char_or_unicode,
+    }
+
+    has_content = True
+
+    def run(self):
+        env = self.state.document.settings.env
+        app = env.app
+
+        namespace = ' '.join(self.content).strip()
+        app.info('documenting plugins from %r' % namespace)
+        overline_style = self.options.get('overline-style', '')
+        underline_style = self.options.get('underline-style', '=')
+
+        def report_load_failure(mgr, ep, err):
+            app.warn(u'Failed to load %s: %s' % (ep.module_name, err))
+
+        mgr = extension.ExtensionManager(
+            namespace,
+            on_load_failure_callback=report_load_failure,
+        )
+
+        result = ViewList()
+
+        if 'detailed' in self.options:
+            data = _detailed_list(
+                mgr, over=overline_style, under=underline_style)
+        else:
+            data = _simple_list(mgr)
+        for text, source in data:
+            for line in text.splitlines():
+                result.append(line, source)
+
+        # Parse what we have into a new section.
+        node = nodes.section()
+        node.document = self.state.document
+        nested_parse_with_titles(self.state, result, node)
+
+        return node.children
+
+
+def setup(app):
+    app.info('loading stevedore.sphinxext')
+    app.add_directive('list-plugins', ListPluginsDirective)
diff --git a/stevedore/tests/test_sphinxext.py b/stevedore/tests/test_sphinxext.py
new file mode 100644
index 0000000..60b4794
--- /dev/null
+++ b/stevedore/tests/test_sphinxext.py
@@ -0,0 +1,120 @@
+#    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
+#
+#         http://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.
+"""Tests for the sphinx extension
+"""
+
+from __future__ import unicode_literals
+
+from stevedore import extension
+from stevedore import sphinxext
+from stevedore.tests import utils
+
+import mock
+import pkg_resources
+
+
+def _make_ext(name, docstring):
+    def inner():
+        pass
+
+    inner.__doc__ = docstring
+    m1 = mock.Mock(spec=pkg_resources.EntryPoint)
+    m1.module_name = '%s_module' % name
+    s = mock.Mock(return_value='ENTRY_POINT(%s)' % name)
+    m1.__str__ = s
+    return extension.Extension(name, m1, inner, None)
+
+
+class TestSphinxExt(utils.TestCase):
+
+    def setUp(self):
+        super(TestSphinxExt, self).setUp()
+        self.exts = [
+            _make_ext('test1', 'One-line docstring'),
+            _make_ext('test2', 'Multi-line docstring\n\nAnother para'),
+        ]
+        self.em = extension.ExtensionManager.make_test_instance(self.exts)
+
+    def test_simple_list(self):
+        results = list(sphinxext._simple_list(self.em))
+        self.assertEqual(
+            [
+                ('* test1 -- One-line docstring', 'test1_module'),
+                ('* test2 -- Multi-line docstring', 'test2_module'),
+            ],
+            results,
+        )
+
+    def test_simple_list_no_docstring(self):
+        ext = [_make_ext('nodoc', None)]
+        em = extension.ExtensionManager.make_test_instance(ext)
+        results = list(sphinxext._simple_list(em))
+        self.assertEqual(
+            [
+                ('* nodoc -- ', 'nodoc_module'),
+            ],
+            results,
+        )
+
+    def test_detailed_list(self):
+        results = list(sphinxext._detailed_list(self.em))
+        self.assertEqual(
+            [
+                ('test1', 'test1_module'),
+                ('-----', 'test1_module'),
+                ('\n', 'test1_module'),
+                ('One-line docstring', 'test1_module'),
+                ('\n', 'test1_module'),
+                ('test2', 'test2_module'),
+                ('-----', 'test2_module'),
+                ('\n', 'test2_module'),
+                ('Multi-line docstring\n\nAnother para', 'test2_module'),
+                ('\n', 'test2_module'),
+            ],
+            results,
+        )
+
+    def test_detailed_list_format(self):
+        results = list(sphinxext._detailed_list(self.em, over='+', under='+'))
+        self.assertEqual(
+            [
+                ('+++++', 'test1_module'),
+                ('test1', 'test1_module'),
+                ('+++++', 'test1_module'),
+                ('\n', 'test1_module'),
+                ('One-line docstring', 'test1_module'),
+                ('\n', 'test1_module'),
+                ('+++++', 'test2_module'),
+                ('test2', 'test2_module'),
+                ('+++++', 'test2_module'),
+                ('\n', 'test2_module'),
+                ('Multi-line docstring\n\nAnother para', 'test2_module'),
+                ('\n', 'test2_module'),
+            ],
+            results,
+        )
+
+    def test_detailed_list_no_docstring(self):
+        ext = [_make_ext('nodoc', None)]
+        em = extension.ExtensionManager.make_test_instance(ext)
+        results = list(sphinxext._detailed_list(em))
+        self.assertEqual(
+            [
+                ('nodoc', 'nodoc_module'),
+                ('-----', 'nodoc_module'),
+                ('\n', 'nodoc_module'),
+                ('.. warning:: No documentation found in ENTRY_POINT(nodoc)',
+                 'nodoc_module'),
+                ('\n', 'nodoc_module'),
+            ],
+            results,
+        )