pyproject.toml support (#893)

* pyproject.toml support

* small refactoring

* add error handling

* fix document and add CHANGELOG entry

* add test for pyproject.toml as config file

* add install_requires on setup.cfg

* fix test function

* import toml conditionally

* raise import error

CHANGELOG

@@ -9,6 +9,8 @@
   a custom number of blank lines between top-level imports and variable
   definitions.
 - Ignore end of line `# copybara:` directives when checking line length.
+- Look at the 'pyproject.toml' file to see if it contains style information for
+  YAPF.
 ### Changed
 - Do not scan exlcuded directories. Prior versions would scan an exluded
   folder then exclude its contents on a file by file basis. Preventing the

README.rst

@@ -113,10 +113,10 @@ Options::
       --style STYLE         specify formatting style: either a style name (for
                             example "pep8" or "google"), or the name of a file
                             with style settings. The default is pep8 unless a
-                            .style.yapf or setup.cfg file located in the same
-                            directory as the source or one of its parent
-                            directories (for stdin, the current directory is
-                            used).
+                            .style.yapf or setup.cfg or pyproject.toml file
+                            located in the same directory as the source or one of
+                            its parent directories (for stdin, the current
+                            directory is used).
       --style-help          show style settings and exit; this output can be saved
                             to .style.yapf to make your settings permanent
       --no-local-style      don't search for local style definition
@@ -198,7 +198,9 @@ YAPF will search for the formatting style in the following manner:
    directory or one of its parent directories.
 3. In the ``[yapf]`` section of a ``setup.cfg`` file in either the current
    directory or one of its parent directories.
-4. In the ``[style]`` section of a ``~/.config/yapf/style`` file in your home
+4. In the ``[tool.yapf]`` section of a ``pyproject.toml`` file in either the current
+   directory or one of its parent directories.
+5. In the ``[style]`` section of a ``~/.config/yapf/style`` file in your home
    directory.
 
 If none of those files are found, the default style is used (PEP8).
@@ -351,9 +353,10 @@ Options::
       --style STYLE         specify formatting style: either a style name (for
                             example "pep8" or "google"), or the name of a file
                             with style settings. The default is pep8 unless a
-                            .style.yapf or setup.cfg file located in one of the
-                            parent directories of the source file (or current
-                            directory for stdin)
+                            .style.yapf or setup.cfg or pyproject.toml file
+                            located in the same directory as the source or one of
+                            its parent directories (for stdin, the current
+                            directory is used).
       --binary BINARY       location of binary to use for yapf
 
 Knobs

yapf/__init__.py

@@ -325,10 +325,10 @@ def _BuildParser():
       action='store',
       help=('specify formatting style: either a style name (for example "pep8" '
             'or "google"), or the name of a file with style settings. The '
-            'default is pep8 unless a %s or %s file located in the same '
+            'default is pep8 unless a %s or %s or %s file located in the same '
             'directory as the source or one of its parent directories '
             '(for stdin, the current directory is used).' %
-            (style.LOCAL_STYLE, style.SETUP_CONFIG)))
+            (style.LOCAL_STYLE, style.SETUP_CONFIG, style.PYPROJECT_TOML)))
   parser.add_argument(
       '--style-help',
       action='store_true',

yapf/yapflib/file_resources.py

@@ -67,7 +67,7 @@ def GetExcludePatternsForDir(dirname):
 def GetDefaultStyleForDir(dirname, default_style=style.DEFAULT_STYLE):
   """Return default style name for a given directory.
 
-  Looks for .style.yapf or setup.cfg in the parent directories.
+  Looks for .style.yapf or setup.cfg or pyproject.toml in the parent directories.
 
   Arguments:
     dirname: (unicode) The name of the directory.
@@ -97,6 +97,26 @@ def GetDefaultStyleForDir(dirname, default_style=style.DEFAULT_STYLE):
         if config.has_section('yapf'):
           return config_file
 
+    # See if we have a pyproject.toml file with a '[tool.yapf]'  section.
+    config_file = os.path.join(dirname, style.PYPROJECT_TOML)
+    try:
+      fd = open(config_file)
+    except IOError:
+      pass  # It's okay if it's not there.
+    else:
+      with fd:
+        try:
+          import toml
+        except ImportError:
+          raise errors.YapfError(
+              "toml package is needed for using pyproject.toml as a configuration file"
+          )
+
+        pyproject_toml = toml.load(config_file)
+        style_dict = pyproject_toml.get('tool', {}).get('yapf', None)
+        if style_dict is not None:
+          return config_file
+
     if (not dirname or not os.path.basename(dirname) or
         dirname == os.path.abspath(os.path.sep)):
       break

yapf/yapflib/style.py

@@ -742,19 +742,40 @@ def _CreateConfigParserFromConfigFile(config_filename):
         '"{0}" is not a valid style or file path'.format(config_filename))
   with open(config_filename) as style_file:
     config = py3compat.ConfigParser()
+    if config_filename.endswith(PYPROJECT_TOML):
+      try:
+        import toml
+      except ImportError:
+        raise errors.YapfError(
+            "toml package is needed for using pyproject.toml as a configuration file"
+        )
+
+      pyproject_toml = toml.load(style_file)
+      style_dict = pyproject_toml.get("tool", {}).get("yapf", None)
+      if style_dict is None:
+        raise StyleConfigError(
+            'Unable to find section [tool.yapf] in {0}'.format(config_filename))
+      config.add_section('style')
+      for k, v in style_dict.items():
+        config.set('style', k, str(v))
+      return config
+
     config.read_file(style_file)
     if config_filename.endswith(SETUP_CONFIG):
       if not config.has_section('yapf'):
         raise StyleConfigError(
             'Unable to find section [yapf] in {0}'.format(config_filename))
-    elif config_filename.endswith(LOCAL_STYLE):
-      if not config.has_section('style'):
-        raise StyleConfigError(
-            'Unable to find section [style] in {0}'.format(config_filename))
-    else:
+      return config
+
+    if config_filename.endswith(LOCAL_STYLE):
       if not config.has_section('style'):
         raise StyleConfigError(
             'Unable to find section [style] in {0}'.format(config_filename))
+      return config
+
+    if not config.has_section('style'):
+      raise StyleConfigError(
+          'Unable to find section [style] in {0}'.format(config_filename))
     return config
 
 
@@ -817,6 +838,10 @@ def _CreateStyleFromConfigParser(config):
 # specified in the '[yapf]' section.
 SETUP_CONFIG = 'setup.cfg'
 
+# Style definition by local pyproject.toml file. Style should be specified
+# in the '[tool.yapf]' section.
+PYPROJECT_TOML = 'pyproject.toml'
+
 # TODO(eliben): For now we're preserving the global presence of a style dict.
 # Refactor this so that the style is passed around through yapf rather than
 # being global.

yapftests/file_resources_test.py

@@ -117,6 +117,21 @@ def test_setup_config(self):
     self.assertEqual(setup_config,
                      file_resources.GetDefaultStyleForDir(test_dir))
 
+  def test_pyproject_toml(self):
+    # An empty pyproject.toml file should not be used
+    pyproject_toml = os.path.join(self.test_tmpdir, 'pyproject.toml')
+    open(pyproject_toml, 'w').close()
+
+    test_dir = os.path.join(self.test_tmpdir, 'dir1')
+    style_name = file_resources.GetDefaultStyleForDir(test_dir)
+    self.assertEqual(style_name, 'pep8')
+
+    # One with a '[tool.yapf]' section should be used
+    with open(pyproject_toml, 'w') as f:
+      f.write('[tool.yapf]\n')
+    self.assertEqual(pyproject_toml,
+                     file_resources.GetDefaultStyleForDir(test_dir))
+
   def test_local_style_at_root(self):
     # Test behavior of files located on the root, and under root.
     rootdir = os.path.abspath(os.path.sep)

yapftests/style_test.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 """Tests for yapf.style."""
 
+import os
 import shutil
 import tempfile
 import textwrap
@@ -226,6 +227,26 @@ def testErrorUnknownStyleOption(self):
                                    'Unknown style option'):
         style.CreateStyleFromConfig(filepath)
 
+  def testPyprojectTomlNoYapfSection(self):
+    filepath = os.path.join(self.test_tmpdir, 'pyproject.toml')
+    _ = open(filepath, 'w')
+    with self.assertRaisesRegexp(style.StyleConfigError,
+                                 'Unable to find section'):
+      style.CreateStyleFromConfig(filepath)
+
+  def testPyprojectTomlParseYapfSection(self):
+    cfg = textwrap.dedent(u'''\
+        [tool.yapf]
+        based_on_style = "pep8"
+        continuation_indent_width = 40
+        ''')
+    filepath = os.path.join(self.test_tmpdir, 'pyproject.toml')
+    with open(filepath, 'w') as f:
+        f.write(cfg)
+    cfg = style.CreateStyleFromConfig(filepath)
+    self.assertTrue(_LooksLikePEP8Style(cfg))
+    self.assertEqual(cfg['CONTINUATION_INDENT_WIDTH'], 40)
+
 
 class StyleFromDict(unittest.TestCase):