~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2007, 2008 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Support for plugin hooking logic."""

from bzrlib import registry

from bzrlib.lazy_import import lazy_import

from bzrlib.symbol_versioning import deprecated_method

lazy_import(globals(), """

import textwrap

from bzrlib import (

        _format_version_tuple,

        errors,

        )

from bzrlib.help_topics import help_as_plain_text

""")

known_hooks = registry.Registry()

# known_hooks registry contains

# tuple of (module, member name) which is the hook point

# module where the specific hooks are defined

# callable to get the empty specific Hooks for that attribute

known_hooks.register_lazy(('bzrlib.branch', 'Branch.hooks'), 'bzrlib.branch',

    'BranchHooks')

known_hooks.register_lazy(('bzrlib.bzrdir', 'BzrDir.hooks'), 'bzrlib.bzrdir',

    'BzrDirHooks')

known_hooks.register_lazy(('bzrlib.commands', 'Command.hooks'),

    'bzrlib.commands', 'CommandHooks')

known_hooks.register_lazy(('bzrlib.info', 'hooks'),

    'bzrlib.info', 'InfoHooks')

known_hooks.register_lazy(('bzrlib.lock', 'Lock.hooks'), 'bzrlib.lock',

    'LockHooks')

known_hooks.register_lazy(('bzrlib.msgeditor', 'hooks'), 'bzrlib.msgeditor',

    'MessageEditorHooks')

known_hooks.register_lazy(('bzrlib.mutabletree', 'MutableTree.hooks'),

    'bzrlib.mutabletree', 'MutableTreeHooks')

known_hooks.register_lazy(('bzrlib.smart.client', '_SmartClient.hooks'),

    'bzrlib.smart.client', 'SmartClientHooks')

known_hooks.register_lazy(('bzrlib.smart.server', 'SmartTCPServer.hooks'),

    'bzrlib.smart.server', 'SmartServerHooks')

known_hooks.register_lazy(

    ('bzrlib.version_info_formats.format_rio', 'RioVersionInfoBuilder.hooks'),

    'bzrlib.version_info_formats.format_rio', 'RioVersionInfoBuilderHooks')

known_hooks.register_lazy(

    ('bzrlib.merge_directive', '_BaseMergeDirective.hooks'),

    'bzrlib.merge_directive', 'MergeDirectiveHooks')

def known_hooks_key_to_object((module_name, member_name)):

    """Convert a known_hooks key to a object.

    :param key: A tuple (module_name, member_name) as found in the keys of

        the known_hooks registry.

    :return: The object this specifies.

    """

    return registry._LazyObjectGetter(module_name, member_name).get_obj()

def known_hooks_key_to_parent_and_attribute((module_name, member_name)):

    """Convert a known_hooks key to a object.

    :param key: A tuple (module_name, member_name) as found in the keys of

        the known_hooks registry.

    :return: The object this specifies.

    """

    member_list = member_name.rsplit('.', 1)

    if len(member_list) == 2:

        parent_name, attribute = member_list

    else:

        parent_name = None

        attribute = member_name

    parent = known_hooks_key_to_object((module_name, parent_name))

    return parent, attribute

class Hooks(dict):

    """A dictionary mapping hook name to a list of callables.

    e.g. ['FOO'] Is the list of items to be called when the

    FOO hook is triggered.

    """

    def __init__(self):

        dict.__init__(self)

        self._callable_names = {}

    def create_hook(self, hook):

        """Create a hook which can have callbacks registered for it.

        :param hook: The hook to create. An object meeting the protocol of

            bzrlib.hooks.HookPoint. It's name is used as the key for future

            lookups.

        """

        if hook.name in self:

            raise errors.DuplicateKey(hook.name)

        self[hook.name] = hook

    def docs(self):

        """Generate the documentation for this Hooks instance.

        This introspects all the individual hooks and returns their docs as well.

        """

        hook_names = sorted(self.keys())

        hook_docs = []

        name = self.__class__.__name__

        hook_docs.append(name)

        hook_docs.append("-"*len(name))

        hook_docs.append("")

        for hook_name in hook_names:

            hook = self[hook_name]

            try:

                hook_docs.append(hook.docs())

            except AttributeError:

                # legacy hook

                strings = []

                strings.append(hook_name)

                strings.append("~" * len(hook_name))

                strings.append("")

                strings.append("An old-style hook. For documentation see the __init__ "

                    "method of '%s'\n" % (name,))

                hook_docs.extend(strings)

        return "\n".join(hook_docs)

    def get_hook_name(self, a_callable):

        """Get the name for a_callable for UI display.

        If no name has been registered, the string 'No hook name' is returned.

        We use a fixed string rather than repr or the callables module because

        the code names are rarely meaningful for end users and this is not

        intended for debugging.

        """

        return self._callable_names.get(a_callable, "No hook name")

    def install_named_hook(self, hook_name, a_callable, name):

        """Install a_callable in to the hook hook_name, and label it name.

        :param hook_name: A hook name. See the __init__ method of BranchHooks

            for the complete list of hooks.

        :param a_callable: The callable to be invoked when the hook triggers.

            The exact signature will depend on the hook - see the __init__

            method of BranchHooks for details on each hook.

        :param name: A name to associate a_callable with, to show users what is

            running.

        """

        try:

            hook = self[hook_name]

        except KeyError:

            raise errors.UnknownHook(self.__class__.__name__, hook_name)

        try:

            # list hooks, old-style, not yet deprecated but less useful.

            hook.append(a_callable)

        except AttributeError:

            hook.hook(a_callable, name)

        if name is not None:

            self.name_hook(a_callable, name)

    def name_hook(self, a_callable, name):

        """Associate name with a_callable to show users what is running."""

        self._callable_names[a_callable] = name

class HookPoint(object):

    """A single hook that clients can register to be called back when it fires.

    :ivar name: The name of the hook.

    :ivar introduced: A version tuple specifying what version the hook was

        introduced in. None indicates an unknown version.

    :ivar deprecated: A version tuple specifying what version the hook was

        deprecated or superseded in. None indicates that the hook is not

        superseded or deprecated. If the hook is superseded then the doc

        should describe the recommended replacement hook to register for.

    :ivar doc: The docs for using the hook.

    """

    def __init__(self, name, doc, introduced, deprecated):

        """Create a HookPoint.

        :param name: The name of the hook, for clients to use when registering.

        :param doc: The docs for the hook.

        :param introduced: When the hook was introduced (e.g. (0, 15)).

        :param deprecated: When the hook was deprecated, None for

            not-deprecated.

        """

        self.name = name

        self.__doc__ = doc

        self.introduced = introduced

        self.deprecated = deprecated

        self._callbacks = []

        self._callback_names = {}

    def docs(self):

        """Generate the documentation for this HookPoint.

        :return: A string terminated in \n.

        """

        strings = []

        strings.append(self.name)

        strings.append('~'*len(self.name))

        strings.append('')

        if self.introduced:

            introduced_string = _format_version_tuple(self.introduced)

        else:

            introduced_string = 'unknown'

        strings.append('Introduced in: %s' % introduced_string)

        if self.deprecated:

            deprecated_string = _format_version_tuple(self.deprecated)

            strings.append('Deprecated in: %s' % deprecated_string)

        strings.append('')

        strings.extend(textwrap.wrap(self.__doc__,

            break_long_words=False))

        strings.append('')

        return '\n'.join(strings)

    def __eq__(self, other):

        return (type(other) == type(self) and 

            other.__dict__ == self.__dict__)

    def hook(self, callback, callback_label):

        """Register a callback to be called when this HookPoint fires.

        :param callback: The callable to use when this HookPoint fires.

        :param callback_label: A label to show in the UI while this callback is

            processing.

        """

        self._callbacks.append(callback)

        if callback_label is not None:

            self._callback_names[callback] = callback_label

    def __iter__(self):

        return iter(self._callbacks)

    def __len__(self):

        return len(self._callbacks)

    def __repr__(self):

        strings = []

        strings.append("<%s(" % type(self).__name__)

        strings.append(self.name)

        strings.append("), callbacks=[")

        for callback in self._callbacks:

            strings.append(repr(callback))

            strings.append("(")

            strings.append(self._callback_names[callback])

            strings.append("),")

        if len(self._callbacks) == 1:

            strings[-1] = ")"

        strings.append("]>")

        return ''.join(strings)

_help_prefix = \

"""

Hooks

=====

Introduction

------------

A hook of type *xxx* of class *yyy* needs to be registered using::

  yyy.hooks.install_named_hook("xxx", ...)

See `Using hooks`_ in the User Guide for examples.

.. _Using hooks: ../user-guide/index.html#using-hooks

The class that contains each hook is given before the hooks it supplies. For

instance, BranchHooks as the class is the hooks class for

`bzrlib.branch.Branch.hooks`.

Each description also indicates whether the hook runs on the client (the

machine where bzr was invoked) or the server (the machine addressed by

the branch URL).  These may be, but are not necessarily, the same machine.

Plugins (including hooks) are run on the server if all of these is true:

  * The connection is via a smart server (accessed with a URL starting with

    "bzr://", "bzr+ssh://" or "bzr+http://", or accessed via a "http://"

    URL when a smart server is available via HTTP).

  * The hook is either server specific or part of general infrastructure rather

    than client specific code (such as commit).

"""

def hooks_help_text(topic):

    segments = [_help_prefix]

    for hook_key in sorted(known_hooks.keys()):

        hooks = known_hooks_key_to_object(hook_key)

        segments.append(hooks.docs())

    return '\n'.join(segments)