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66aee8094f
All logging now prefers the ' (single quote) over the " (double quote) https://github.com/sampsyo/beets/wiki/Hacking
379 lines
11 KiB
Python
Executable file
379 lines
11 KiB
Python
Executable file
# This file is part of beets.
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# Copyright 2013, Adrian Sampson.
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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"""Support for beets plugins."""
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import logging
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import traceback
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from collections import defaultdict
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import inspect
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import beets
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from beets import mediafile
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PLUGIN_NAMESPACE = 'beetsplug'
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# Plugins using the Last.fm API can share the same API key.
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LASTFM_KEY = '2dc3914abf35f0d9c92d97d8f8e42b43'
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# Global logger.
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log = logging.getLogger('beets')
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# Managing the plugins themselves.
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class BeetsPlugin(object):
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"""The base class for all beets plugins. Plugins provide
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functionality by defining a subclass of BeetsPlugin and overriding
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the abstract methods defined here.
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"""
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def __init__(self, name=None):
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"""Perform one-time plugin setup.
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"""
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self.import_stages = []
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self.name = name or self.__module__.split('.')[-1]
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self.config = beets.config[self.name]
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if not self.template_funcs:
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self.template_funcs = {}
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if not self.template_fields:
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self.template_fields = {}
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if not self.album_template_fields:
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self.album_template_fields = {}
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def commands(self):
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"""Should return a list of beets.ui.Subcommand objects for
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commands that should be added to beets' CLI.
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"""
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return ()
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def queries(self):
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"""Should return a dict mapping prefixes to Query subclasses.
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"""
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return {}
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def track_distance(self, item, info):
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"""Should return a Distance object to be added to the
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distance for every track comparison.
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"""
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return beets.autotag.hooks.Distance()
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def album_distance(self, items, album_info, mapping):
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"""Should return a Distance object to be added to the
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distance for every album-level comparison.
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"""
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return beets.autotag.hooks.Distance()
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def candidates(self, items, artist, album, va_likely):
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"""Should return a sequence of AlbumInfo objects that match the
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album whose items are provided.
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"""
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return ()
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def item_candidates(self, item, artist, title):
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"""Should return a sequence of TrackInfo objects that match the
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item provided.
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"""
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return ()
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def album_for_id(self, album_id):
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"""Return an AlbumInfo object or None if no matching release was
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found.
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"""
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return None
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def track_for_id(self, track_id):
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"""Return a TrackInfo object or None if no matching release was
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found.
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"""
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return None
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def add_media_field(self, name, descriptor):
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"""Add a field that is synchronized between media files and items.
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When a media field is added ``item.write()`` will set the name
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property of the item's MediaFile to ``item[name]`` and save the
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changes. Similarly ``item.read()`` will set ``item[name]`` to
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the value of the name property of the media file.
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``descriptor`` must be an instance of ``mediafile.MediaField``.
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"""
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# Defer impor to prevent circular dependency
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from beets import library
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mediafile.MediaFile.add_field(name, descriptor)
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library.Item._media_fields.add(name)
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listeners = None
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@classmethod
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def register_listener(cls, event, func):
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"""Add a function as a listener for the specified event. (An
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imperative alternative to the @listen decorator.)
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"""
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if cls.listeners is None:
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cls.listeners = defaultdict(list)
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cls.listeners[event].append(func)
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@classmethod
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def listen(cls, event):
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"""Decorator that adds a function as an event handler for the
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specified event (as a string). The parameters passed to function
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will vary depending on what event occurred.
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The function should respond to named parameters.
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function(**kwargs) will trap all arguments in a dictionary.
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Example:
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>>> @MyPlugin.listen("imported")
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>>> def importListener(**kwargs):
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>>> pass
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"""
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def helper(func):
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if cls.listeners is None:
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cls.listeners = defaultdict(list)
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cls.listeners[event].append(func)
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return func
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return helper
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template_funcs = None
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template_fields = None
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album_template_fields = None
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@classmethod
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def template_func(cls, name):
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"""Decorator that registers a path template function. The
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function will be invoked as ``%name{}`` from path format
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strings.
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"""
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def helper(func):
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if cls.template_funcs is None:
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cls.template_funcs = {}
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cls.template_funcs[name] = func
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return func
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return helper
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@classmethod
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def template_field(cls, name):
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"""Decorator that registers a path template field computation.
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The value will be referenced as ``$name`` from path format
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strings. The function must accept a single parameter, the Item
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being formatted.
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"""
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def helper(func):
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if cls.template_fields is None:
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cls.template_fields = {}
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cls.template_fields[name] = func
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return func
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return helper
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_classes = set()
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def load_plugins(names=()):
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"""Imports the modules for a sequence of plugin names. Each name
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must be the name of a Python module under the "beetsplug" namespace
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package in sys.path; the module indicated should contain the
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BeetsPlugin subclasses desired.
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"""
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for name in names:
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modname = '%s.%s' % (PLUGIN_NAMESPACE, name)
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try:
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try:
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namespace = __import__(modname, None, None)
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except ImportError as exc:
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# Again, this is hacky:
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if exc.args[0].endswith(' ' + name):
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log.warn(u'** plugin {0} not found'.format(name))
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else:
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raise
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else:
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for obj in getattr(namespace, name).__dict__.values():
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if isinstance(obj, type) and issubclass(obj, BeetsPlugin) \
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and obj != BeetsPlugin and obj not in _classes:
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_classes.add(obj)
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except:
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log.warn(u'** error loading plugin {0}'.format(name))
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log.warn(traceback.format_exc())
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_instances = {}
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def find_plugins():
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"""Returns a list of BeetsPlugin subclass instances from all
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currently loaded beets plugins. Loads the default plugin set
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first.
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"""
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load_plugins()
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plugins = []
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for cls in _classes:
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# Only instantiate each plugin class once.
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if cls not in _instances:
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_instances[cls] = cls()
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plugins.append(_instances[cls])
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return plugins
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# Communication with plugins.
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def commands():
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"""Returns a list of Subcommand objects from all loaded plugins.
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"""
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out = []
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for plugin in find_plugins():
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out += plugin.commands()
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return out
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def queries():
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"""Returns a dict mapping prefix strings to Query subclasses all loaded
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plugins.
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"""
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out = {}
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for plugin in find_plugins():
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out.update(plugin.queries())
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return out
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def track_distance(item, info):
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"""Gets the track distance calculated by all loaded plugins.
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Returns a Distance object.
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"""
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from beets.autotag.hooks import Distance
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dist = Distance()
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for plugin in find_plugins():
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dist.update(plugin.track_distance(item, info))
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return dist
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def album_distance(items, album_info, mapping):
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"""Returns the album distance calculated by plugins."""
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from beets.autotag.hooks import Distance
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dist = Distance()
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for plugin in find_plugins():
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dist.update(plugin.album_distance(items, album_info, mapping))
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return dist
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def candidates(items, artist, album, va_likely):
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"""Gets MusicBrainz candidates for an album from each plugin.
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"""
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out = []
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for plugin in find_plugins():
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out.extend(plugin.candidates(items, artist, album, va_likely))
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return out
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def item_candidates(item, artist, title):
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"""Gets MusicBrainz candidates for an item from the plugins.
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"""
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out = []
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for plugin in find_plugins():
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out.extend(plugin.item_candidates(item, artist, title))
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return out
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def album_for_id(album_id):
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"""Get AlbumInfo objects for a given ID string.
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"""
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out = []
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for plugin in find_plugins():
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res = plugin.album_for_id(album_id)
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if res:
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out.append(res)
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return out
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def track_for_id(track_id):
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"""Get TrackInfo objects for a given ID string.
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"""
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out = []
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for plugin in find_plugins():
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res = plugin.track_for_id(track_id)
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if res:
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out.append(res)
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return out
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def template_funcs():
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"""Get all the template functions declared by plugins as a
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dictionary.
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"""
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funcs = {}
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for plugin in find_plugins():
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if plugin.template_funcs:
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funcs.update(plugin.template_funcs)
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return funcs
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def import_stages():
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"""Get a list of import stage functions defined by plugins."""
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stages = []
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for plugin in find_plugins():
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if hasattr(plugin, 'import_stages'):
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stages += plugin.import_stages
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return stages
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# New-style (lazy) plugin-provided fields.
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def item_field_getters():
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"""Get a dictionary mapping field names to unary functions that
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compute the field's value.
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"""
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funcs = {}
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for plugin in find_plugins():
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if plugin.template_fields:
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funcs.update(plugin.template_fields)
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return funcs
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def album_field_getters():
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"""As above, for album fields.
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"""
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funcs = {}
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for plugin in find_plugins():
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if plugin.album_template_fields:
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funcs.update(plugin.album_template_fields)
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return funcs
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# Event dispatch.
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def event_handlers():
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"""Find all event handlers from plugins as a dictionary mapping
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event names to sequences of callables.
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"""
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all_handlers = defaultdict(list)
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for plugin in find_plugins():
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if plugin.listeners:
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for event, handlers in plugin.listeners.items():
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all_handlers[event] += handlers
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return all_handlers
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def send(event, **arguments):
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"""Sends an event to all assigned event listeners. Event is the
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name of the event to send, all other named arguments go to the
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event handler(s).
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Returns a list of return values from the handlers.
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"""
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log.debug(u'Sending event: {0}'.format(event))
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for handler in event_handlers()[event]:
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# Don't break legacy plugins if we want to pass more arguments
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argspec = inspect.getargspec(handler).args
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args = dict((k, v) for k, v in arguments.items() if k in argspec)
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handler(**args)
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