Merge branch 'remove_unused_broken_flake8_listen' into 'master'

Remove unused and broken flake8.listen plugin type

Closes #480

See merge request pycqa/flake8!274

5 files changed, 11 insertions, 209 deletions

diff --git a/src/flake8/main/application.py b/src/flake8/main/application.py
index 86d7fd4..ae33b13 100644
--- a/src/flake8/main/application.py
+++ b/src/flake8/main/application.py
@@ -57,14 +57,10 @@ class Application(object):
         self.local_plugins = None
         #: The instance of :class:`flake8.plugins.manager.Checkers`
         self.check_plugins = None
-        #: The instance of :class:`flake8.plugins.manager.Listeners`
-        self.listening_plugins = None
         #: The instance of :class:`flake8.plugins.manager.ReportFormatters`
         self.formatting_plugins = None
         #: The user-selected formatter from :attr:`formatting_plugins`
         self.formatter = None
-        #: The :class:`flake8.plugins.notifier.Notifier` for listening plugins
-        self.listener_trie = None
         #: The :class:`flake8.style_guide.StyleGuideManager` built from the
         #: user's options
         self.guide = None
@@ -166,11 +162,11 @@ class Application(object):
         # type: () -> NoneType
         """Find and load the plugins for this application.
 
-        If :attr:`check_plugins`, :attr:`listening_plugins`, or
-        :attr:`formatting_plugins` are ``None`` then this method will update
-        them with the appropriate plugin manager instance. Given the expense
-        of finding plugins (via :mod:`entrypoints`) we want this to be
-        idempotent and so only update those attributes if they are ``None``.
+        If :attr:`check_plugins`, or :attr:`formatting_plugins` are ``None``
+        then this method will update them with the appropriate plugin manager
+        instance. Given the expense of finding plugins (via :mod:`entrypoints`)
+        we want this to be idempotent and so only update those attributes if
+        they are ``None``.
         """
         if self.local_plugins is None:
             self.local_plugins = config.get_local_plugins(
@@ -186,16 +182,12 @@ class Application(object):
                 self.local_plugins.extension
             )
 
-        if self.listening_plugins is None:
-            self.listening_plugins = plugin_manager.Listeners()
-
         if self.formatting_plugins is None:
             self.formatting_plugins = plugin_manager.ReportFormatters(
                 self.local_plugins.report
             )
 
         self.check_plugins.load_plugins()
-        self.listening_plugins.load_plugins()
         self.formatting_plugins.load_plugins()
 
     def register_plugin_options(self):
@@ -203,7 +195,6 @@ class Application(object):
         """Register options provided by plugins to our option manager."""
         self.check_plugins.register_options(self.option_manager)
         self.check_plugins.register_plugin_versions(self.option_manager)
-        self.listening_plugins.register_options(self.option_manager)
         self.formatting_plugins.register_options(self.option_manager)
 
     def parse_configuration_and_cli(self, argv=None):
@@ -229,9 +220,6 @@ class Application(object):
         self.check_plugins.provide_options(
             self.option_manager, self.options, self.args
         )
-        self.listening_plugins.provide_options(
-            self.option_manager, self.options, self.args
-        )
         self.formatting_plugins.provide_options(
             self.option_manager, self.options, self.args
         )
@@ -264,18 +252,12 @@ class Application(object):
 
             self.formatter = formatter_class(self.options)
 
-    def make_notifier(self):
-        # type: () -> NoneType
-        """Initialize our listener Notifier."""
-        if self.listener_trie is None:
-            self.listener_trie = self.listening_plugins.build_notifier()
-
     def make_guide(self):
         # type: () -> NoneType
         """Initialize our StyleGuide."""
         if self.guide is None:
             self.guide = style_guide.StyleGuideManager(
-                self.options, self.listener_trie, self.formatter
+                self.options, self.formatter
             )
 
         if self.running_against_diff:
@@ -373,7 +355,6 @@ class Application(object):
         self.register_plugin_options()
         self.parse_configuration_and_cli(argv)
         self.make_formatter()
-        self.make_notifier()
         self.make_guide()
         self.make_file_checker_manager()
 
diff --git a/src/flake8/plugins/_trie.py b/src/flake8/plugins/_trie.py
deleted file mode 100644
index 9a50b45..0000000
--- a/src/flake8/plugins/_trie.py
+++ /dev/null
@@ -1,95 +0,0 @@
-"""Independent implementation of a Trie tree."""
-
-__all__ = ("Trie", "TrieNode")
-
-
-def _iterate_stringlike_objects(string):
-    for i in range(len(string)):
-        yield string[i : i + 1]
-
-
-class Trie(object):
-    """The object that manages the trie nodes."""
-
-    def __init__(self):
-        """Initialize an empty trie."""
-        self.root = TrieNode(None, None)
-
-    def add(self, path, node_data):
-        """Add the node data to the path described."""
-        node = self.root
-        for prefix in _iterate_stringlike_objects(path):
-            child = node.find_prefix(prefix)
-            if child is None:
-                child = node.add_child(prefix, [])
-            node = child
-        node.data.append(node_data)
-
-    def find(self, path):
-        """Find a node based on the path provided."""
-        node = self.root
-        for prefix in _iterate_stringlike_objects(path):
-            child = node.find_prefix(prefix)
-            if child is None:
-                return None
-            node = child
-        return node
-
-    def traverse(self):
-        """Traverse this tree.
-
-        This performs a depth-first pre-order traversal of children in this
-        tree. It returns the results consistently by first sorting the
-        children based on their prefix and then traversing them in
-        alphabetical order.
-        """
-        return self.root.traverse()
-
-
-class TrieNode(object):
-    """The majority of the implementation details of a Trie."""
-
-    def __init__(self, prefix, data, children=None):
-        """Initialize a TrieNode with data and children."""
-        self.children = children or {}
-        self.data = data
-        self.prefix = prefix
-
-    def __repr__(self):
-        """Generate an easy to read representation of the node."""
-        return "TrieNode(prefix={0}, data={1})".format(self.prefix, self.data)
-
-    def find_prefix(self, prefix):
-        """Find the prefix in the children of this node.
-
-        :returns: A child matching the prefix or None.
-        :rtype: :class:`~TrieNode` or None
-        """
-        return self.children.get(prefix, None)
-
-    def add_child(self, prefix, data, children=None):
-        """Create and add a new child node.
-
-        :returns: The newly created node
-        :rtype: :class:`~TrieNode`
-        """
-        new_node = TrieNode(prefix, data, children)
-        self.children[prefix] = new_node
-        return new_node
-
-    def traverse(self):
-        """Traverse children of this node.
-
-        This performs a depth-first pre-order traversal of the remaining
-        children in this sub-tree. It returns the results consistently by
-        first sorting the children based on their prefix and then traversing
-        them in alphabetical order.
-        """
-        if not self.children:
-            return
-
-        for prefix in sorted(self.children):
-            child = self.children[prefix]
-            yield child
-            for child in child.traverse():
-                yield child
diff --git a/src/flake8/plugins/manager.py b/src/flake8/plugins/manager.py
index 411e02f..045cfd7 100644
--- a/src/flake8/plugins/manager.py
+++ b/src/flake8/plugins/manager.py
@@ -6,7 +6,6 @@ import entrypoints
 
 from flake8 import exceptions
 from flake8 import utils
-from flake8.plugins import notifier
 
 if sys.version_info >= (3, 3):
     import collections.abc as collections_abc
@@ -15,13 +14,7 @@ else:
 
 LOG = logging.getLogger(__name__)
 
-__all__ = (
-    "Checkers",
-    "Listeners",
-    "Plugin",
-    "PluginManager",
-    "ReportFormatters",
-)
+__all__ = ("Checkers", "Plugin", "PluginManager", "ReportFormatters")
 
 NO_GROUP_FOUND = object()
 
@@ -444,24 +437,6 @@ class PluginTypeManager(object):
         list(self.manager.map(call_provide_options))
 
 
-class NotifierBuilderMixin(object):  # pylint: disable=too-few-public-methods
-    """Mixin class that builds a Notifier from a PluginManager."""
-
-    def build_notifier(self):
-        """Build a Notifier for our Listeners.
-
-        :returns:
-            Object to notify our listeners of certain error codes and
-            warnings.
-        :rtype:
-            :class:`~flake8.notifier.Notifier`
-        """
-        notifier_trie = notifier.Notifier()
-        for name in self.names:
-            notifier_trie.register_listener(name, self.manager[name])
-        return notifier_trie
-
-
 class Checkers(PluginTypeManager):
     """All of the checkers registered through entry-points or config."""
 
@@ -542,12 +517,6 @@ class Checkers(PluginTypeManager):
         return plugins
 
 
-class Listeners(PluginTypeManager, NotifierBuilderMixin):
-    """All of the listeners registered through entry-points or config."""
-
-    namespace = "flake8.listen"
-
-
 class ReportFormatters(PluginTypeManager):
     """All of the report formatters registered through entry-points/config."""
 
diff --git a/src/flake8/plugins/notifier.py b/src/flake8/plugins/notifier.py
deleted file mode 100644
index 9efccd4..0000000
--- a/src/flake8/plugins/notifier.py
+++ /dev/null
@@ -1,46 +0,0 @@
-"""Implementation of the class that registers and notifies listeners."""
-from flake8.plugins import _trie
-
-
-class Notifier(object):
-    """Object that tracks and notifies listener objects."""
-
-    def __init__(self):
-        """Initialize an empty notifier object."""
-        self.listeners = _trie.Trie()
-
-    def listeners_for(self, error_code):
-        """Retrieve listeners for an error_code.
-
-        There may be listeners registered for E1, E100, E101, E110, E112, and
-        E126. To get all the listeners for one of E100, E101, E110, E112, or
-        E126 you would also need to incorporate the listeners for E1 (since
-        they're all in the same class).
-
-        Example usage:
-
-        .. code-block:: python
-
-            from flake8 import notifier
-
-            n = notifier.Notifier()
-            # register listeners
-            for listener in n.listeners_for('W102'):
-                listener.notify(...)
-        """
-        path = error_code
-        while path:
-            node = self.listeners.find(path)
-            listeners = getattr(node, "data", [])
-            for listener in listeners:
-                yield listener
-            path = path[:-1]
-
-    def notify(self, error_code, *args, **kwargs):
-        """Notify all listeners for the specified error code."""
-        for listener in self.listeners_for(error_code):
-            listener.notify(error_code, *args, **kwargs)
-
-    def register_listener(self, error_code, listener):
-        """Register a listener for a specific error_code."""
-        self.listeners.add(error_code, listener)
diff --git a/src/flake8/style_guide.py b/src/flake8/style_guide.py
index 46f72fc..56fa832 100644
--- a/src/flake8/style_guide.py
+++ b/src/flake8/style_guide.py
@@ -325,19 +325,18 @@ class DecisionEngine(object):
 class StyleGuideManager(object):
     """Manage multiple style guides for a single run."""
 
-    def __init__(self, options, listener_trie, formatter, decider=None):
+    def __init__(self, options, formatter, decider=None):
         """Initialize our StyleGuide.
 
         .. todo:: Add parameter documentation.
         """
         self.options = options
-        self.listener = listener_trie
         self.formatter = formatter
         self.stats = statistics.Statistics()
         self.decider = decider or DecisionEngine(options)
         self.style_guides = []
         self.default_style_guide = StyleGuide(
-            options, listener_trie, formatter, decider=decider
+            options, formatter, decider=decider
         )
         self.style_guides = list(
             itertools.chain(
@@ -435,15 +434,12 @@ class StyleGuideManager(object):
 class StyleGuide(object):
     """Manage a Flake8 user's style guide."""
 
-    def __init__(
-        self, options, listener_trie, formatter, filename=None, decider=None
-    ):
+    def __init__(self, options, formatter, filename=None, decider=None):
         """Initialize our StyleGuide.
 
         .. todo:: Add parameter documentation.
         """
         self.options = options
-        self.listener = listener_trie
         self.formatter = formatter
         self.stats = statistics.Statistics()
         self.decider = decider or DecisionEngine(options)
@@ -461,9 +457,7 @@ class StyleGuide(object):
         filename = filename or self.filename
         options = copy.deepcopy(self.options)
         options.ignore.extend(extend_ignore_with or [])
-        return StyleGuide(
-            options, self.listener, self.formatter, filename=filename
-        )
+        return StyleGuide(options, self.formatter, filename=filename)
 
     @contextlib.contextmanager
     def processing_file(self, filename):
@@ -565,7 +559,6 @@ class StyleGuide(object):
         ):
             self.formatter.handle(error)
             self.stats.record(error)
-            self.listener.notify(error.code, error)
             return 1
         return 0