summaryrefslogtreecommitdiff
path: root/portato/plugin.py
blob: 9efe396b640c6cc96375087651cfd38d1a147e60 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
# -*- coding: utf-8 -*-
#
# File: portato/plugin.py
# This file is part of the Portato-Project, a graphical portage-frontend.
#
# Copyright (C) 2006-2009 René 'Necoro' Neumann
# This is free software.  You may redistribute copies of it under the terms of
# the GNU General Public License version 2.
# There is NO WARRANTY, to the extent permitted by law.
#
# Written by René 'Necoro' Neumann <necoro@necoro.net>

"""
A module managing the plugins for Portato.
"""

from __future__ import absolute_import
__docformat__ = "restructuredtext"

import os
import os.path as osp
import traceback
from collections import defaultdict
from functools import wraps

from .helper import debug, warning, info, error
from .constants import PLUGIN_DIR
from .backend import system
from . import plugins as plugin_module

class PluginLoadException (Exception):
    """
    Exception signaling a failed plugin loading.
    """
    pass

class Call (object):
    """
    This class represents an object, which is attached to a specified hook.

    :IVariables:

        plugin : `Plugin`
            The plugin where this call belongs to.

        hook : string
            The name of the corresponding hook.

        call
            The function to call.

        type : string
            This is either ``before``, ``after`` or ``override`` and defines the type of the call:

                before
                    access before the original function
                override
                    access *instead of* the original function. **USE THIS ONLY IF YOU KNOW WHAT YOU ARE DOING**
                after
                    access after the original function has been called

            Default: ``before``

        dep : string
            This defines a plugin which should be executed after/before this one.
            ``"*"`` means all and ``"-*"`` means none.
    """
    __slots__ = ("plugin", "hook", "call", "type", "dep")

    def __init__ (self, plugin, hook, call, type = "before", dep = None):
        self.plugin = plugin
        self.hook = hook
        self.call = call
        self.type = type
        self.dep = dep

class Hook (object):
    """
    Representing a hook with all the `Call` s for the different types.
    """
            
    __slots__ = ("before", "override", "after")

    def __init__ (self):
        self.before = []
        self.override = None
        self.after = []

class WidgetSlot (object):
    """
    A slot, where plugins can add widgets.

    :IVariables:

        widget : gobject.GObjectMeta
            The widget class, which can be used in this slot.

        name : string
            The slot's name.

        init : function
            Function to call, iff there is at least one widget for that slot.

        add : function(`Widget`)
            Function to call, if a widget is added.

        max : int
            The maximum number of widgets which can be registered. -1 means unlimited.

    """
    
    slots = {}
    
    def __init__ (self, widget, name, add = None, init = None, max = -1):
        self.widget = widget
        self.name = name
        self.max = max
        self.init = init
        self.add = add
        self._inited = False

        WidgetSlot.slots[name] = self

    def add_widget (self, w):
        if not self._inited:
            if self.init is not None:
                self.init()
            self._inited = True

        self.add(w)

class Widget (object):
    """
    Fills a WidgetSlot.

    :IVariables:

        slot : string
            The name of the slot to fill.

        widget : gtk.Widget
            The widget which is added.

    """

    __slots__ = ("slot", "widget")

    def __init__ (self, slot, widget):
        self.slot = slot
        self.widget = widget

class Plugin (object):
    """
    This is the main plugin object. It is used where ever a plugin is wanted, and it is the one, which needs to be subclassed by plugin authors.

    :CVariables:

        STAT_DISABLED : status
            Status: Disabled.

        STAT_TEMP_ENABLED : status
            Status: Enabled for this session only.

        STAT_ENABLED : status
            Status: Enabled.

        STAT_TEMP_DISABLED : status
            Status: Disabled for this session only.

        STAT_HARD_DISABLED : status
            Status: Forced disabled by program (i.e. because of errors in the plugin).
    """

    (STAT_DISABLED, STAT_TEMP_ENABLED, STAT_ENABLED, STAT_TEMP_DISABLED) = range(4)
    STAT_HARD_DISABLED = -1

    def __init__ (self, disable = False):
        """
        :param disable: Forcefully disable the plugin
        :type disable: bool
        """
        self.__widgets = [] #: List of `Widget`
        self.__calls = [] #: List of `Call`
        self._unresolved_deps = False #: Does this plugin has unresolved dependencies?

        self.status = self.STAT_ENABLED #: The status of this plugin
        
        if disable:
            self.status = self.STAT_HARD_DISABLED

    def _init (self):
        """
        Method called from outside to init the extension parts of this plugin.
        If the current status is `STAT_HARD_DISABLED` or there are unresolved dependencies, the init process is not started.
        """

        for d in self.deps:
            if not system.find_packages(d, pkgSet=system.SET_INSTALLED, with_version = False):
                self._unresolved_deps = True
                break
        
        if self.status != self.STAT_HARD_DISABLED and not self._unresolved_deps:
            self.init()
    
    def init (self):
        """
        This method is called by `_init` and should be overriden by the plugin author.

        :precond: No unresolved deps and the status is not `STAT_HARD_DISABLED`.
        """
        pass

    @property
    def author (self):
        """
        Returns the plugin's author.
        The author is given by the ``__author__`` variable.

        :rtype: string
        """
        return getattr(self, "__author__", "")

    @property
    def description (self):
        """
        Returns the description of this plugin.
        It is given by either a ``__description__`` variable or by the normal class docstring.

        :rtype: string
        """
        if hasattr(self, "__description__"):
            return self.__description__
        else:
            doc = getattr(self, "__doc__", "")

            if not doc or doc == Plugin.__doc__:
                return ""
            else:
                return doc

    @property
    def name (self):
        """
        The name of the plugin. If no ``__name__`` variable is given, the class name is taken.

        :rtype: string
        """
        return getattr(self, "__name__", self.__class__.__name__)

    @property
    def widgets (self):
        """
        Returns an iterator over the widgets for this plugin.

        :rtype: iter<`Widget`>
        """
        return iter(self.__widgets)

    @property
    def calls (self):
        """
        Returns an iterator over the registered calls for this plugin.

        :rtype: iter<`Call`>
        """
        return iter(self.__calls)

    @property
    def deps (self):
        """
        Returns an iterator of the dependencies or ``[]`` if there are none.
        The dependencies are given in the ``__dependency__`` variable.

        :rtype: [] or iter<string>
        """
        if hasattr(self, "__dependency__"):
            return iter(self.__dependency__)
        else:
            return []

    @property
    def enabled (self):
        """
        Returns ``True`` if the plugin is enabled.

        :rtype: boolean
        :see: `status`
        """
        return (self.status in (self.STAT_ENABLED, self.STAT_TEMP_ENABLED))
    
    def add_widget (self, slot, widget):
        """
        Adds a new widget for this plugin.

        :see: `Widget`
        """
        self.__widgets.append(Widget(slot, widget))

    def create_widget (self, slot, args, **kwargs):
        """
        Creates a new widget for the plugin.

        :Parameters:
            
            slot : string
                The slot to create a widget for.

            args : list of objects
                The arguments to pass to the widget constructor.

            kwargs : dict
                Additional named parameters are for callback functions.
        """

        try:
            widget = WidgetSlot.slots[slot].widget
        except KeyError:
            raise PluginLoadException, "Could not find specified widget slot: %s" % slot

        w = widget(*args)

        for k,v in kwargs.iteritems():
            w.connect(k, v)

        self.add_widget(slot, w)

    def add_call (self, hook, callable, type = "before", dep = None):
        """
        Adds a new call for this plugin.

        :see: `Call`
        """
        self.__calls.append(Call(self, hook, callable, type, dep))


class PluginQueue (object):
    """
    Class managing and loading the plugins.
    
    :IVariables:

        plugins : `Plugin` []
            The list of managed plugins.

        hooks : string -> `Hook`
            For each hook name map to a `Hook` object holding the corresponding `Call` objects.
    """

    def __init__ (self):
        """
        Constructor.
        """

        self.plugins = []
        self.hooks = defaultdict(Hook)

    def get_plugins (self, list_disabled = True):
        """
        Returns the plugins.

        :param list_disabled: Also list disabled plugins.
        :type list_disabled: boolean

        :rtype: iter<`Plugin`>
        """
        return (x for x in self.plugins if (x.enabled or list_disabled))

    def load (self):
        """
        Load the plugins.
        
        This method scans the `portato.constants.PLUGIN_DIR` for python modules and tries to load them. If the modules are real plugins,
        they have called `register` and thus the plugins are added.
        """

        # look them up
        plugins = []
        for f in os.listdir(PLUGIN_DIR):
            path = osp.join(PLUGIN_DIR, f)
            if osp.isdir(path):
                if osp.isfile(osp.join(path, "__init__.py")):
                    plugins.append(f)
                else:
                    debug("'%s' is not a plugin: __init__.py missing", path)
            else:
                if f.endswith(".py"):
                    plugins.append(f[:-3])
                elif f.endswith(".pyc") or f.endswith(".pyo"):
                    pass # ignore .pyc and .pyo
                else:
                    debug("'%s' is not a plugin: not a .py file", path)

        # some magic ...
        plugin_module.__path__.insert(0, PLUGIN_DIR.rstrip("/")) # make the plugins loadable as "portato.plugins.name"
        # add Plugin and register to the builtins, so the plugins always have the correct version :)
        plugin_module.__builtins__["Plugin"] = Plugin
        plugin_module.__builtins__["register"] = register

        for p in plugins: # import them
            try:
                exec "from portato.plugins import %s" % p in {}
            except PluginLoadException, e:
                error(_("Loading plugin '%(plugin)s' failed: %(error)s"), {"plugin" : p, "error" : e.message})
            except:
                tb = traceback.format_exc()
                error(_("Loading plugin '%(plugin)s' failed: %(error)s"), {"plugin" : p, "error" : tb})

        self._organize()

        for p in self.plugins:
            for w in p.widgets:
                WidgetSlot[w.slot].add_widget(w)

    def add (self, plugin, disable = False):
        """
        Adds a plugin to the internal list.

        :Parameters:

            plugin : `Plugin`
                ``Plugin`` subclass or instance to add. If a class is passed, it is instantiated.

            disable : boolean
                Disable the plugin.

        :raise PluginLoadException: passed plugin is not of class `Plugin`
        """

        if callable(plugin) and Plugin in plugin.__bases__:
            p = plugin(disable = disable) # need an instance and not the class
        elif isinstance(plugin, Plugin):
            p = plugin
            if disable:
                p.status = p.STAT_HARD_DISABLED
        else:
            raise PluginLoadException, "Is neither a subclass nor an instance of Plugin."

        p._init()

        self.plugins.append(p)
        
        if p.status == p.STAT_HARD_DISABLED:
            msg = _("Plugin is disabled!")
        elif p._unresolved_deps:
            msg = _("Plugin has unresolved dependencies - disabled!")
        else:
            msg = ""
        
        info("%s %s", _("Plugin '%s' loaded.") % p.name, msg)

    def hook (self, hook, *hargs, **hkwargs):
        """
        The decorator to use in the program.
        All parameters except ``hook`` are passed to plugins.

        :param hook: the name of the hook
        :type hook: string
        """

        def hook_decorator (func):
            """
            The real decorator.
            """
            h = self.hooks[hook]

            active = Hook()

            # remove disabled
            for type in ("before", "after"):
                calls = getattr(h, type)
                aCalls = getattr(active, type)
                for call in calls:
                    if call.plugin.enabled:
                        aCalls.append(call)

            if h.override and h.override.plugin.enabled:
                active.override = h.override

            @wraps(func)
            def wrapper (*args, **kwargs):
                ret = None

                # before
                for call in active.before:
                    debug("Accessing hook '%(hook)s' of plugin '%(plugin)s' (before).", {"hook" : hook, "plugin": call.plugin.name})
                    call.call(*hargs, **hkwargs)
                
                if active.override: # override
                    info(_("Overriding hook '%(hook)s' with plugin '%(plugin)s'."), {"hook": hook, "plugin": active.override.plugin.name})
                    ret = active.override.call(*hargs, **hkwargs)
                else: # normal
                    ret = func(*args, **kwargs)

                # after
                for call in active.after:
                    debug("Accessing hook '%(hook)s' of plugin '%(plugin)s' (after).", {"hook": hook, "plugin": call.plugin.name})
                    call.call(*hargs, **hkwargs)

                return ret

            return wrapper

        return hook_decorator

    def _organize (self):
        """
        Organizes the lists of `Call` in a way, that all dependencies are fullfilled.
        """
        unresolved_before = defaultdict(list)
        unresolved_after = defaultdict(list)
        star_before = defaultdict(Hook) # should be _before_ all other
        star_after = defaultdict(Hook) # should be _after_ all other

        for plugin in self.plugins: # plugins
            for call in plugin.calls: # hooks in plugin
                if call.type == "before":
                    if call.dep is None: # no dependency -> straight add
                        self.hooks[call.hook].before.append(call)
                    elif call.dep == "*":
                        self.hooks[call.hook].before.insert(0, call)
                    elif call.dep == "-*":
                        star_before[call.hook].append(call)
                    else:
                        named = [x.plugin.name for x in self.hooks[call.hook].before]
                        if call.dep in named:
                            self.hooks[call.hook].before.insert(named.index(call.dep), call)
                        else:
                            unresolved_before[call.hook].append(call)

                elif call.type == "after":
                    if call.dep is None: # no dependency -> straight add
                        self.hooks[call.hook].after.append(call)
                    elif call.dep == "*":
                        star_after[call.hook].append(call)
                    elif call.dep == "-*":
                        self.hooks[call.hook].after.insert(0, call)
                    else:
                        named = [x.plugin.name for x in self.hooks[call.hook].after]
                        if call.dep in named:
                            self.hooks[call.hook].after.insert(named.index(call.dep)+1, call)
                        else:
                            unresolved_after[call.hook].append(call)
                
                # type = "override"
                elif call.type == "override":
                    if self.hooks[call.hook].override:
                        warning(_("For hook '%(hook)s' an override is already defined by plugin '%(plugin)s'!"), {"hook": call.hook, "plugin": self.hooks[call.hook].override.plugin.name})
                        warning(_("It is now replaced by the one from plugin '%s'!"), call.plugin.name)
                    
                    self.hooks[call.hook].override = call
                    continue
        
        self._resolve_unresolved(unresolved_before, unresolved_after)

        for hook, calls in star_before.iteritems():
            self.hooks[hook].before.extend(calls) # append the list

        for hook, calls in star_after.iteritems():
            self.hooks[hook].after.extend(calls) # append the list

    def _resolve_unresolved (self, before, after):
        def resolve(hook, list, type, add):
            if not list:
                return
            
            callList = getattr(self.hooks[hook], type)
            named = [x.plugin.name for x in callList]

            while list and named:
                newNamed = [] # use newNamed, so in each iteration only the plugins inserted last are searched
                for call in list[:]:
                    if call.dep in named:
                        callList.insert(named.index(call.dep)+add, call)
                        list.remove(call)
                        newNamed.append(call.plugin.name)

                named = newNamed

            for l in list:
                callList.append(l)
                info(_("Dependant '%(dep)s' for '%(hook)s' in plugin '%(plugin)s' not found! Adding nevertheless."), {"hook": hook, "plugin": l.plugin.name, "dep": l.dep})

        for hook in before:
            resolve(hook, before[hook], "before", 0)
        
        for hook in after:
            resolve(hook, after[hook], "after", 1)


__plugins = None

def load_plugins():
    """
    Loads the plugins.
    """
    
    global __plugins
    if __plugins is None:
        __plugins = PluginQueue()
        __plugins.load()
    

def get_plugin_queue():
    """
    Returns the actual `PluginQueue`. If it is ``None``, they are not being loaded yet.

    :rtype: `PluginQueue` or ``None``"""
    return __plugins

def hook(hook, *args, **kwargs):
    """
    Shortcut to `PluginQueue.hook`. If no `PluginQueue` is loaded, this does nothing.
    """
    if __plugins is None:
        def pseudo_decorator(f):
            return f
        return pseudo_decorator
    else:
        return __plugins.hook(hook, *args, **kwargs)

def register (plugin, disable = False):
    """
    Registers a plugin.

    :see: `PluginQueue.add`
    """
    if __plugins is not None:
        __plugins.add(plugin, disable)