mercurial/thirdparty/zope/interface/adapter.py
author Joerg Sonnenberger <joerg@bec.de>
Fri, 30 Apr 2021 02:11:58 +0200
changeset 47043 12450fbea288
parent 37178 68ee61822182
permissions -rw-r--r--
manifests: push down expected node length into the parser This strictly enforces the node length in the manifest lines according to what the repository expects. One test case moves large hash testing into the non-treemanifest part as treemanifests don't provide an interface for overriding just the node length for now. Differential Revision: https://phab.mercurial-scm.org/D10533

##############################################################################
#
# Copyright (c) 2004 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL).  A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""Adapter management
"""
from __future__ import absolute_import

import weakref

from . import implementer
from . import providedBy
from . import Interface
from . import ro
from .interfaces import IAdapterRegistry

from ._compat import _normalize_name
from ._compat import STRING_TYPES

_BLANK = u''

class BaseAdapterRegistry(object):

    # List of methods copied from lookup sub-objects:
    _delegated = ('lookup', 'queryMultiAdapter', 'lookup1', 'queryAdapter',
                  'adapter_hook', 'lookupAll', 'names',
                  'subscriptions', 'subscribers')

    # All registries maintain a generation that can be used by verifying
    # registries
    _generation = 0

    def __init__(self, bases=()):

        # The comments here could be improved. Possibly this bit needs
        # explaining in a separate document, as the comments here can
        # be quite confusing. /regebro

        # {order -> {required -> {provided -> {name -> value}}}}
        # Here "order" is actually an index in a list, "required" and
        # "provided" are interfaces, and "required" is really a nested
        # key.  So, for example:
        # for order == 0 (that is, self._adapters[0]), we have:
        #   {provided -> {name -> value}}
        # but for order == 2 (that is, self._adapters[2]), we have:
        #   {r1 -> {r2 -> {provided -> {name -> value}}}}
        #
        self._adapters = []

        # {order -> {required -> {provided -> {name -> [value]}}}}
        # where the remarks about adapters above apply
        self._subscribers = []

        # Set, with a reference count, keeping track of the interfaces
        # for which we have provided components:
        self._provided = {}

        # Create ``_v_lookup`` object to perform lookup.  We make this a
        # separate object to to make it easier to implement just the
        # lookup functionality in C.  This object keeps track of cache
        # invalidation data in two kinds of registries.

        #   Invalidating registries have caches that are invalidated
        #     when they or their base registies change.  An invalidating
        #     registry can only have invalidating registries as bases.
        #     See LookupBaseFallback below for the pertinent logic.

        #   Verifying registies can't rely on getting invalidation messages,
        #     so have to check the generations of base registries to determine
        #     if their cache data are current.  See VerifyingBasePy below
        #     for the pertinent object.
        self._createLookup()

        # Setting the bases causes the registries described above
        # to be initialized (self._setBases -> self.changed ->
        # self._v_lookup.changed).

        self.__bases__ = bases

    def _setBases(self, bases):
        self.__dict__['__bases__'] = bases
        self.ro = ro.ro(self)
        self.changed(self)

    __bases__ = property(lambda self: self.__dict__['__bases__'],
                         lambda self, bases: self._setBases(bases),
                         )

    def _createLookup(self):
        self._v_lookup = self.LookupClass(self)
        for name in self._delegated:
            self.__dict__[name] = getattr(self._v_lookup, name)

    def changed(self, originally_changed):
        self._generation += 1
        self._v_lookup.changed(originally_changed)

    def register(self, required, provided, name, value):
        if not isinstance(name, STRING_TYPES):
            raise ValueError('name is not a string')
        if value is None:
            self.unregister(required, provided, name, value)
            return

        required = tuple(map(_convert_None_to_Interface, required))
        name = _normalize_name(name)
        order = len(required)
        byorder = self._adapters
        while len(byorder) <= order:
            byorder.append({})
        components = byorder[order]
        key = required + (provided,)

        for k in key:
            d = components.get(k)
            if d is None:
                d = {}
                components[k] = d
            components = d

        if components.get(name) is value:
            return

        components[name] = value

        n = self._provided.get(provided, 0) + 1
        self._provided[provided] = n
        if n == 1:
            self._v_lookup.add_extendor(provided)

        self.changed(self)

    def registered(self, required, provided, name=_BLANK):
        required = tuple(map(_convert_None_to_Interface, required))
        name = _normalize_name(name)
        order = len(required)
        byorder = self._adapters
        if len(byorder) <= order:
            return None

        components = byorder[order]
        key = required + (provided,)

        for k in key:
            d = components.get(k)
            if d is None:
                return None
            components = d

        return components.get(name)

    def unregister(self, required, provided, name, value=None):
        required = tuple(map(_convert_None_to_Interface, required))
        order = len(required)
        byorder = self._adapters
        if order >= len(byorder):
            return False
        components = byorder[order]
        key = required + (provided,)

        # Keep track of how we got to `components`:
        lookups = []
        for k in key:
            d = components.get(k)
            if d is None:
                return
            lookups.append((components, k))
            components = d

        old = components.get(name)
        if old is None:
            return
        if (value is not None) and (old is not value):
            return

        del components[name]
        if not components:
            # Clean out empty containers, since we don't want our keys
            # to reference global objects (interfaces) unnecessarily.
            # This is often a problem when an interface is slated for
            # removal; a hold-over entry in the registry can make it
            # difficult to remove such interfaces.
            for comp, k in reversed(lookups):
                d = comp[k]
                if d:
                    break
                else:
                    del comp[k]
            while byorder and not byorder[-1]:
                del byorder[-1]
        n = self._provided[provided] - 1
        if n == 0:
            del self._provided[provided]
            self._v_lookup.remove_extendor(provided)
        else:
            self._provided[provided] = n

        self.changed(self)

    def subscribe(self, required, provided, value):
        required = tuple(map(_convert_None_to_Interface, required))
        name = _BLANK
        order = len(required)
        byorder = self._subscribers
        while len(byorder) <= order:
            byorder.append({})
        components = byorder[order]
        key = required + (provided,)

        for k in key:
            d = components.get(k)
            if d is None:
                d = {}
                components[k] = d
            components = d

        components[name] = components.get(name, ()) + (value, )

        if provided is not None:
            n = self._provided.get(provided, 0) + 1
            self._provided[provided] = n
            if n == 1:
                self._v_lookup.add_extendor(provided)

        self.changed(self)

    def unsubscribe(self, required, provided, value=None):
        required = tuple(map(_convert_None_to_Interface, required))
        order = len(required)
        byorder = self._subscribers
        if order >= len(byorder):
            return
        components = byorder[order]
        key = required + (provided,)

        # Keep track of how we got to `components`:
        lookups = []
        for k in key:
            d = components.get(k)
            if d is None:
                return
            lookups.append((components, k))
            components = d

        old = components.get(_BLANK)
        if not old:
            # this is belt-and-suspenders against the failure of cleanup below
            return  # pragma: no cover

        if value is None:
            new = ()
        else:
            new = tuple([v for v in old if v is not value])

        if new == old:
            return

        if new:
            components[_BLANK] = new
        else:
            # Instead of setting components[_BLANK] = new, we clean out
            # empty containers, since we don't want our keys to
            # reference global objects (interfaces) unnecessarily.  This
            # is often a problem when an interface is slated for
            # removal; a hold-over entry in the registry can make it
            # difficult to remove such interfaces.
            del components[_BLANK]
            for comp, k in reversed(lookups):
                d = comp[k]
                if d:
                    break
                else:
                    del comp[k]
            while byorder and not byorder[-1]:
                del byorder[-1]

        if provided is not None:
            n = self._provided[provided] + len(new) - len(old)
            if n == 0:
                del self._provided[provided]
                self._v_lookup.remove_extendor(provided)

        self.changed(self)

    # XXX hack to fake out twisted's use of a private api.  We need to get them
    # to use the new registed method.
    def get(self, _): # pragma: no cover
        class XXXTwistedFakeOut:
            selfImplied = {}
        return XXXTwistedFakeOut


_not_in_mapping = object()
class LookupBaseFallback(object):

    def __init__(self):
        self._cache = {}
        self._mcache = {}
        self._scache = {}

    def changed(self, ignored=None):
        self._cache.clear()
        self._mcache.clear()
        self._scache.clear()

    def _getcache(self, provided, name):
        cache = self._cache.get(provided)
        if cache is None:
            cache = {}
            self._cache[provided] = cache
        if name:
            c = cache.get(name)
            if c is None:
                c = {}
                cache[name] = c
            cache = c
        return cache

    def lookup(self, required, provided, name=_BLANK, default=None):
        if not isinstance(name, STRING_TYPES):
            raise ValueError('name is not a string')
        cache = self._getcache(provided, name)
        required = tuple(required)
        if len(required) == 1:
            result = cache.get(required[0], _not_in_mapping)
        else:
            result = cache.get(tuple(required), _not_in_mapping)

        if result is _not_in_mapping:
            result = self._uncached_lookup(required, provided, name)
            if len(required) == 1:
                cache[required[0]] = result
            else:
                cache[tuple(required)] = result

        if result is None:
            return default

        return result

    def lookup1(self, required, provided, name=_BLANK, default=None):
        if not isinstance(name, STRING_TYPES):
            raise ValueError('name is not a string')
        cache = self._getcache(provided, name)
        result = cache.get(required, _not_in_mapping)
        if result is _not_in_mapping:
            return self.lookup((required, ), provided, name, default)

        if result is None:
            return default

        return result

    def queryAdapter(self, object, provided, name=_BLANK, default=None):
        return self.adapter_hook(provided, object, name, default)

    def adapter_hook(self, provided, object, name=_BLANK, default=None):
        if not isinstance(name, STRING_TYPES):
            raise ValueError('name is not a string')
        required = providedBy(object)
        cache = self._getcache(provided, name)
        factory = cache.get(required, _not_in_mapping)
        if factory is _not_in_mapping:
            factory = self.lookup((required, ), provided, name)

        if factory is not None:
            result = factory(object)
            if result is not None:
                return result

        return default

    def lookupAll(self, required, provided):
        cache = self._mcache.get(provided)
        if cache is None:
            cache = {}
            self._mcache[provided] = cache

        required = tuple(required)
        result = cache.get(required, _not_in_mapping)
        if result is _not_in_mapping:
            result = self._uncached_lookupAll(required, provided)
            cache[required] = result

        return result


    def subscriptions(self, required, provided):
        cache = self._scache.get(provided)
        if cache is None:
            cache = {}
            self._scache[provided] = cache

        required = tuple(required)
        result = cache.get(required, _not_in_mapping)
        if result is _not_in_mapping:
            result = self._uncached_subscriptions(required, provided)
            cache[required] = result

        return result

LookupBasePy = LookupBaseFallback # BBB

try:
    from ._zope_interface_coptimizations import LookupBase
except ImportError:
    LookupBase = LookupBaseFallback


class VerifyingBaseFallback(LookupBaseFallback):
    # Mixin for lookups against registries which "chain" upwards, and
    # whose lookups invalidate their own caches whenever a parent registry
    # bumps its own '_generation' counter.  E.g., used by
    # zope.component.persistentregistry

    def changed(self, originally_changed):
        LookupBaseFallback.changed(self, originally_changed)
        self._verify_ro = self._registry.ro[1:]
        self._verify_generations = [r._generation for r in self._verify_ro]

    def _verify(self):
        if ([r._generation for r in self._verify_ro]
            != self._verify_generations):
            self.changed(None)

    def _getcache(self, provided, name):
        self._verify()
        return LookupBaseFallback._getcache(self, provided, name)

    def lookupAll(self, required, provided):
        self._verify()
        return LookupBaseFallback.lookupAll(self, required, provided)

    def subscriptions(self, required, provided):
        self._verify()
        return LookupBaseFallback.subscriptions(self, required, provided)

VerifyingBasePy = VerifyingBaseFallback #BBB

try:
    from ._zope_interface_coptimizations import VerifyingBase
except ImportError:
    VerifyingBase = VerifyingBaseFallback


class AdapterLookupBase(object):

    def __init__(self, registry):
        self._registry = registry
        self._required = {}
        self.init_extendors()
        super(AdapterLookupBase, self).__init__()

    def changed(self, ignored=None):
        super(AdapterLookupBase, self).changed(None)
        for r in self._required.keys():
            r = r()
            if r is not None:
                r.unsubscribe(self)
        self._required.clear()


    # Extendors
    # ---------

    # When given an target interface for an adapter lookup, we need to consider
    # adapters for interfaces that extend the target interface.  This is
    # what the extendors dictionary is about.  It tells us all of the
    # interfaces that extend an interface for which there are adapters
    # registered.

    # We could separate this by order and name, thus reducing the
    # number of provided interfaces to search at run time.  The tradeoff,
    # however, is that we have to store more information.  For example,
    # if the same interface is provided for multiple names and if the
    # interface extends many interfaces, we'll have to keep track of
    # a fair bit of information for each name.  It's better to
    # be space efficient here and be time efficient in the cache
    # implementation.

    # TODO: add invalidation when a provided interface changes, in case
    # the interface's __iro__ has changed.  This is unlikely enough that
    # we'll take our chances for now.

    def init_extendors(self):
        self._extendors = {}
        for p in self._registry._provided:
            self.add_extendor(p)

    def add_extendor(self, provided):
        _extendors = self._extendors
        for i in provided.__iro__:
            extendors = _extendors.get(i, ())
            _extendors[i] = (
                [e for e in extendors if provided.isOrExtends(e)]
                +
                [provided]
                +
                [e for e in extendors if not provided.isOrExtends(e)]
                )

    def remove_extendor(self, provided):
        _extendors = self._extendors
        for i in provided.__iro__:
            _extendors[i] = [e for e in _extendors.get(i, ())
                             if e != provided]


    def _subscribe(self, *required):
        _refs = self._required
        for r in required:
            ref = r.weakref()
            if ref not in _refs:
                r.subscribe(self)
                _refs[ref] = 1

    def _uncached_lookup(self, required, provided, name=_BLANK):
        required = tuple(required)
        result = None
        order = len(required)
        for registry in self._registry.ro:
            byorder = registry._adapters
            if order >= len(byorder):
                continue

            extendors = registry._v_lookup._extendors.get(provided)
            if not extendors:
                continue

            components = byorder[order]
            result = _lookup(components, required, extendors, name, 0,
                             order)
            if result is not None:
                break

        self._subscribe(*required)

        return result

    def queryMultiAdapter(self, objects, provided, name=_BLANK, default=None):
        factory = self.lookup(map(providedBy, objects), provided, name)
        if factory is None:
            return default

        result = factory(*objects)
        if result is None:
            return default

        return result

    def _uncached_lookupAll(self, required, provided):
        required = tuple(required)
        order = len(required)
        result = {}
        for registry in reversed(self._registry.ro):
            byorder = registry._adapters
            if order >= len(byorder):
                continue
            extendors = registry._v_lookup._extendors.get(provided)
            if not extendors:
                continue
            components = byorder[order]
            _lookupAll(components, required, extendors, result, 0, order)

        self._subscribe(*required)

        return tuple(result.items())

    def names(self, required, provided):
        return [c[0] for c in self.lookupAll(required, provided)]

    def _uncached_subscriptions(self, required, provided):
        required = tuple(required)
        order = len(required)
        result = []
        for registry in reversed(self._registry.ro):
            byorder = registry._subscribers
            if order >= len(byorder):
                continue

            if provided is None:
                extendors = (provided, )
            else:
                extendors = registry._v_lookup._extendors.get(provided)
                if extendors is None:
                    continue

            _subscriptions(byorder[order], required, extendors, _BLANK,
                           result, 0, order)

        self._subscribe(*required)

        return result

    def subscribers(self, objects, provided):
        subscriptions = self.subscriptions(map(providedBy, objects), provided)
        if provided is None:
            result = ()
            for subscription in subscriptions:
                subscription(*objects)
        else:
            result = []
            for subscription in subscriptions:
                subscriber = subscription(*objects)
                if subscriber is not None:
                    result.append(subscriber)
        return result

class AdapterLookup(AdapterLookupBase, LookupBase):
    pass

@implementer(IAdapterRegistry)
class AdapterRegistry(BaseAdapterRegistry):

    LookupClass = AdapterLookup

    def __init__(self, bases=()):
        # AdapterRegisties are invalidating registries, so
        # we need to keep track of out invalidating subregistries.
        self._v_subregistries = weakref.WeakKeyDictionary()

        super(AdapterRegistry, self).__init__(bases)

    def _addSubregistry(self, r):
        self._v_subregistries[r] = 1

    def _removeSubregistry(self, r):
        if r in self._v_subregistries:
            del self._v_subregistries[r]

    def _setBases(self, bases):
        old = self.__dict__.get('__bases__', ())
        for r in old:
            if r not in bases:
                r._removeSubregistry(self)
        for r in bases:
            if r not in old:
                r._addSubregistry(self)

        super(AdapterRegistry, self)._setBases(bases)

    def changed(self, originally_changed):
        super(AdapterRegistry, self).changed(originally_changed)

        for sub in self._v_subregistries.keys():
            sub.changed(originally_changed)


class VerifyingAdapterLookup(AdapterLookupBase, VerifyingBase):
    pass

@implementer(IAdapterRegistry)
class VerifyingAdapterRegistry(BaseAdapterRegistry):

    LookupClass = VerifyingAdapterLookup

def _convert_None_to_Interface(x):
    if x is None:
        return Interface
    else:
        return x

def _lookup(components, specs, provided, name, i, l):
    if i < l:
        for spec in specs[i].__sro__:
            comps = components.get(spec)
            if comps:
                r = _lookup(comps, specs, provided, name, i+1, l)
                if r is not None:
                    return r
    else:
        for iface in provided:
            comps = components.get(iface)
            if comps:
                r = comps.get(name)
                if r is not None:
                    return r

    return None

def _lookupAll(components, specs, provided, result, i, l):
    if i < l:
        for spec in reversed(specs[i].__sro__):
            comps = components.get(spec)
            if comps:
                _lookupAll(comps, specs, provided, result, i+1, l)
    else:
        for iface in reversed(provided):
            comps = components.get(iface)
            if comps:
                result.update(comps)

def _subscriptions(components, specs, provided, name, result, i, l):
    if i < l:
        for spec in reversed(specs[i].__sro__):
            comps = components.get(spec)
            if comps:
                _subscriptions(comps, specs, provided, name, result, i+1, l)
    else:
        for iface in reversed(provided):
            comps = components.get(iface)
            if comps:
                comps = comps.get(name)
                if comps:
                    result.extend(comps)