/brz/remove-bazaar

# Copyright (C) 2006, 2009 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

"""A collection of extra help information for using bzr.

Help topics are meant to be help for items that aren't commands, but will

help bzr become fully learnable without referring to a tutorial.

Limited formatting of help text is permitted to make the text useful

both within the reference manual (reStructuredText) and on the screen.

The help text should be reStructuredText with formatting kept to a

minimum and, in particular, no headings. The onscreen renderer applies

the following simple rules before rendering the text:

    1. A '::' appearing on the end of a line is replaced with ':'.

    2. Lines starting with a ':' have it stripped.

These rules mean that literal blocks and field lists respectively can

be used in the help text, producing sensible input to a manual while

rendering on the screen naturally.

"""

import sys

import bzrlib

from bzrlib import (

    osutils,

    registry,

    )

# Section identifiers (map topics to the right place in the manual)

SECT_COMMAND = "command"

SECT_CONCEPT = "concept"

SECT_HIDDEN =  "hidden"

SECT_LIST    = "list"

SECT_PLUGIN  = "plugin"

class HelpTopicRegistry(registry.Registry):

    """A Registry customized for handling help topics."""

    def register(self, topic, detail, summary, section=SECT_LIST):

        """Register a new help topic.

        :param topic: Name of documentation entry

        :param detail: Function or string object providing detailed

            documentation for topic.  Function interface is detail(topic).

            This should return a text string of the detailed information.

            See the module documentation for details on help text formatting.

        :param summary: String providing single-line documentation for topic.

        :param section: Section in reference manual - see SECT_* identifiers.

        """

        # The detail is stored as the 'object' and the metadata as the info

        info=(summary,section)

        super(HelpTopicRegistry, self).register(topic, detail, info=info)

    def register_lazy(self, topic, module_name, member_name, summary,

                      section=SECT_LIST):

        """Register a new help topic, and import the details on demand.

        :param topic: Name of documentation entry

        :param module_name: The module to find the detailed help.

        :param member_name: The member of the module to use for detailed help.

        :param summary: String providing single-line documentation for topic.

        :param section: Section in reference manual - see SECT_* identifiers.

        """

        # The detail is stored as the 'object' and the metadata as the info

        info=(summary,section)

        super(HelpTopicRegistry, self).register_lazy(topic, module_name,

                                                     member_name, info=info)

    def get_detail(self, topic):

        """Get the detailed help on a given topic."""

        obj = self.get(topic)

        if callable(obj):

            return obj(topic)

        else:

            return obj

    def get_summary(self, topic):

        """Get the single line summary for the topic."""

        info = self.get_info(topic)

        if info is None:

            return None

        else:

            return info[0]

    def get_section(self, topic):

        """Get the section for the topic."""

        info = self.get_info(topic)

        if info is None:

            return None

        else:

            return info[1]

    def get_topics_for_section(self, section):

        """Get the set of topics in a section."""

        result = set()

        for topic in self.keys():

            if section == self.get_section(topic):

                result.add(topic)

        return result

topic_registry = HelpTopicRegistry()

#----------------------------------------------------

def _help_on_topics(dummy):

    """Write out the help for topics to outfile"""

    topics = topic_registry.keys()

    lmax = max(len(topic) for topic in topics)

    out = []

    for topic in topics:

        summary = topic_registry.get_summary(topic)

        out.append("%-*s %s\n" % (lmax, topic, summary))

    return ''.join(out)

def _load_from_file(topic_name):

    """Load help from a file.

    Topics are expected to be txt files in bzrlib.help_topics.

    """

    resource_name = osutils.pathjoin("en", "%s.txt" % (topic_name,))

    return osutils.resource_string('bzrlib.help_topics', resource_name)

def _help_on_revisionspec(name):

    """Generate the help for revision specs."""

    import re

    import bzrlib.revisionspec

    out = []

    out.append(

"""Revision Identifiers

A revision identifier refers to a specific state of a branch's history.  It

can be expressed in several ways.  It can begin with a keyword to

unambiguously specify a given lookup type; some examples are 'last:1',

'before:yesterday' and 'submit:'.

Alternately, it can be given without a keyword, in which case it will be

checked as a revision number, a tag, a revision id, a date specification, or a

branch specification, in that order.  For example, 'date:today' could be

written as simply 'today', though if you have a tag called 'today' that will

be found first.

If 'REV1' and 'REV2' are revision identifiers, then 'REV1..REV2' denotes a

revision range. Examples: '3647..3649', 'date:yesterday..-1' and

'branch:/path/to/branch1/..branch:/branch2' (note that there are no quotes or

spaces around the '..').

Ranges are interpreted differently by different commands. To the "log" command,

a range is a sequence of log messages, but to the "diff" command, the range

denotes a change between revisions (and not a sequence of changes).  In

addition, "log" considers a closed range whereas "diff" and "merge" consider it

to be open-ended, that is, they include one end but not the other.  For example:

"bzr log -r 3647..3649" shows the messages of revisions 3647, 3648 and 3649,

while "bzr diff -r 3647..3649" includes the changes done in revisions 3648 and

3649, but not 3647.

The keywords used as revision selection methods are the following:

""")

    details = []

    details.append("\nIn addition, plugins can provide other keywords.")

    details.append("\nA detailed description of each keyword is given below.\n")

    # The help text is indented 4 spaces - this re cleans that up below

    indent_re = re.compile(r'^    ', re.MULTILINE)

    for prefix, i in bzrlib.revisionspec.revspec_registry.iteritems():

        doc = i.help_txt

        if doc == bzrlib.revisionspec.RevisionSpec.help_txt:

            summary = "N/A"

            doc = summary + "\n"

        else:

            # Extract out the top line summary from the body and

            # clean-up the unwanted whitespace

            summary,doc = doc.split("\n", 1)

            #doc = indent_re.sub('', doc)

            while (doc[-2:] == '\n\n' or doc[-1:] == ' '):

                doc = doc[:-1]

        # Note: The leading : here are HACKs to get reStructuredText

        # 'field' formatting - we know that the prefix ends in a ':'.

        out.append(":%s\n\t%s" % (i.prefix, summary))

        details.append(":%s\n%s" % (i.prefix, doc))

    return '\n'.join(out + details)

def _help_on_transport(name):

    from bzrlib.transport import (

        transport_list_registry,

    )

    import textwrap

    def add_string(proto, help, maxl, prefix_width=20):

       help_lines = textwrap.wrap(help, maxl - prefix_width,

            break_long_words=False)

       line_with_indent = '\n' + ' ' * prefix_width

       help_text = line_with_indent.join(help_lines)

       return "%-20s%s\n" % (proto, help_text)

    def sort_func(a,b):

        a1 = a[:a.rfind("://")]

        b1 = b[:b.rfind("://")]

        if a1>b1:

            return +1

        elif a1<b1:

            return -1

        else:

            return 0

    protl = []

    decl = []

    protos = transport_list_registry.keys( )

    protos.sort(sort_func)

    for proto in protos:

        shorthelp = transport_list_registry.get_help(proto)

        if not shorthelp:

            continue

        if proto.endswith("://"):

            protl.append(add_string(proto, shorthelp, 79))

        else:

            decl.append(add_string(proto, shorthelp, 79))

    out = "URL Identifiers\n\n" + \

            "Supported URL prefixes::\n\n  " + \

            '  '.join(protl)

    if len(decl):

        out += "\nSupported modifiers::\n\n  " + \

            '  '.join(decl)

    out += """\

\nBazaar supports all of the standard parts within the URL::

  <protocol>://[user[:password]@]host[:port]/[path]

allowing URLs such as::

  http://bzruser:BadPass@bzr.example.com:8080/bzr/trunk

For bzr+ssh:// and sftp:// URLs, Bazaar also supports paths that begin

with '~' as meaning that the rest of the path should be interpreted

relative to the remote user's home directory.  For example if the user

``remote`` has a  home directory of ``/home/remote`` on the server

shell.example.com, then::

  bzr+ssh://remote@shell.example.com/~/myproject/trunk

would refer to ``/home/remote/myproject/trunk``.

"""

    return out

_basic_help = \

"""Bazaar -- a free distributed version-control tool

http://bazaar-vcs.org/

Basic commands:

  bzr init           makes this directory a versioned branch

  bzr branch         make a copy of another branch

  bzr add            make files or directories versioned

  bzr ignore         ignore a file or pattern

  bzr mv             move or rename a versioned file

  bzr status         summarize changes in working copy

  bzr diff           show detailed diffs

  bzr merge          pull in changes from another branch

  bzr commit         save some or all changes

  bzr send           send changes via email

  bzr log            show history of changes

  bzr check          validate storage

  bzr help init      more help on e.g. init command

  bzr help commands  list all commands

  bzr help topics    list all help topics

"""

_global_options = \

"""Global Options

These options may be used with any command, and may appear in front of any

command.  (e.g. "bzr --profile help").

--version      Print the version number. Must be supplied before the command.

--no-aliases   Do not process command aliases when running this command.

--builtin      Use the built-in version of a command, not the plugin version.

               This does not suppress other plugin effects.

--no-plugins   Do not process any plugins.

--concurrency  Number of processes that can be run concurrently (selftest).

--profile      Profile execution using the hotshot profiler.

--lsprof       Profile execution using the lsprof profiler.

--lsprof-file  Profile execution using the lsprof profiler, and write the

               results to a specified file.  If the filename ends with ".txt",

               text format will be used.  If the filename either starts with

               "callgrind.out" or end with ".callgrind", the output will be

               formatted for use with KCacheGrind. Otherwise, the output

               will be a pickle.

--coverage     Generate line coverage report in the specified directory.

See doc/developers/profiling.txt for more information on profiling.

A number of debug flags are also available to assist troubleshooting and

development.  See `bzr help debug-flags`.

"""

_standard_options = \

"""Standard Options

Standard options are legal for all commands.

--help, -h     Show help message.

--verbose, -v  Display more information.

--quiet, -q    Only display errors and warnings.

Unlike global options, standard options can be used in aliases.

"""

_checkouts = \

"""Checkouts

Checkouts are source trees that are connected to a branch, so that when

you commit in the source tree, the commit goes into that branch.  They

allow you to use a simpler, more centralized workflow, ignoring some of

Bazaar's decentralized features until you want them. Using checkouts

with shared repositories is very similar to working with SVN or CVS, but

doesn't have the same restrictions.  And using checkouts still allows

others working on the project to use whatever workflow they like.

A checkout is created with the bzr checkout command (see "help checkout").

You pass it a reference to another branch, and it will create a local copy

for you that still contains a reference to the branch you created the

checkout from (the master branch). Then if you make any commits they will be

made on the other branch first. This creates an instant mirror of your work, or

facilitates lockstep development, where each developer is working together,

continuously integrating the changes of others.

However the checkout is still a first class branch in Bazaar terms, so that

you have the full history locally.  As you have a first class branch you can

also commit locally if you want, for instance due to the temporary loss af a

network connection. Use the --local option to commit to do this. All the local

commits will then be made on the master branch the next time you do a non-local

commit.

If you are using a checkout from a shared branch you will periodically want to

pull in all the changes made by others. This is done using the "update"

command. The changes need to be applied before any non-local commit, but

Bazaar will tell you if there are any changes and suggest that you use this

command when needed.

It is also possible to create a "lightweight" checkout by passing the

--lightweight flag to checkout. A lightweight checkout is even closer to an

SVN checkout in that it is not a first class branch, it mainly consists of the

working tree. This means that any history operations must query the master

branch, which could be slow if a network connection is involved. Also, as you

don't have a local branch, then you cannot commit locally.

Lightweight checkouts work best when you have fast reliable access to the

master branch. This means that if the master branch is on the same disk or LAN

a lightweight checkout will be faster than a heavyweight one for any commands

that modify the revision history (as only one copy of the branch needs to

be updated). Heavyweight checkouts will generally be faster for any command

that uses the history but does not change it, but if the master branch is on

the same disk then there won't be a noticeable difference.

Another possible use for a checkout is to use it with a treeless repository

containing your branches, where you maintain only one working tree by

switching the master branch that the checkout points to when you want to

work on a different branch.

Obviously to commit on a checkout you need to be able to write to the master

branch. This means that the master branch must be accessible over a writeable

protocol , such as sftp://, and that you have write permissions at the other

end. Checkouts also work on the local file system, so that all that matters is

file permissions.

You can change the master of a checkout by using the "bind" command (see "help

bind"). This will change the location that the commits are sent to. The bind

command can also be used to turn a branch into a heavy checkout. If you

would like to convert your heavy checkout into a normal branch so that every

commit is local, you can use the "unbind" command. To see whether or not a

branch is bound or not you can use the "info" command. If the branch is bound

it will tell you the location of the bound branch.

Related commands::

  checkout    Create a checkout. Pass --lightweight to get a lightweight

              checkout

  update      Pull any changes in the master branch in to your checkout

  commit      Make a commit that is sent to the master branch. If you have

              a heavy checkout then the --local option will commit to the

              checkout without sending the commit to the master

  bind        Change the master branch that the commits in the checkout will

              be sent to

  unbind      Turn a heavy checkout into a standalone branch so that any

              commits are only made locally

  info        Displays whether a branch is bound or unbound. If the branch is

              bound, then it will also display the location of the bound branch

"""

_repositories = \

"""Repositories

Repositories in Bazaar are where committed information is stored. There is

a repository associated with every branch.

Repositories are a form of database. Bzr will usually maintain this for

good performance automatically, but in some situations (e.g. when doing

very many commits in a short time period) you may want to ask bzr to

optimise the database indices. This can be done by the 'bzr pack' command.

By default just running 'bzr init' will create a repository within the new

branch but it is possible to create a shared repository which allows multiple

branches to share their information in the same location. When a new branch is

created it will first look to see if there is a containing shared repository it

can use.

When two branches of the same project share a repository, there is

generally a large space saving. For some operations (e.g. branching

within the repository) this translates in to a large time saving.

To create a shared repository use the init-repository command (or the alias

init-repo). This command takes the location of the repository to create. This

means that 'bzr init-repository repo' will create a directory named 'repo',

which contains a shared repository. Any new branches that are created in this

directory will then use it for storage.

It is a good idea to create a repository whenever you might create more

than one branch of a project. This is true for both working areas where you

are doing the development, and any server areas that you use for hosting

projects. In the latter case, it is common to want branches without working

trees. Since the files in the branch will not be edited directly there is no

need to use up disk space for a working tree. To create a repository in which

the branches will not have working trees pass the '--no-trees' option to

'init-repository'.

Related commands::

  init-repository   Create a shared repository. Use --no-trees to create one

                    in which new branches won't get a working tree.

"""

_working_trees = \

"""Working Trees

A working tree is the contents of a branch placed on disk so that you can

see the files and edit them. The working tree is where you make changes to a

branch, and when you commit the current state of the working tree is the

snapshot that is recorded in the commit.

When you push a branch to a remote system, a working tree will not be

created. If one is already present the files will not be updated. The

branch information will be updated and the working tree will be marked

as out-of-date. Updating a working tree remotely is difficult, as there

may be uncommitted changes or the update may cause content conflicts that are

difficult to deal with remotely.

If you have a branch with no working tree you can use the 'checkout' command

to create a working tree. If you run 'bzr checkout .' from the branch it will

create the working tree. If the branch is updated remotely, you can update the

working tree by running 'bzr update' in that directory.

If you have a branch with a working tree that you do not want the 'remove-tree'

command will remove the tree if it is safe. This can be done to avoid the

warning about the remote working tree not being updated when pushing to the

branch. It can also be useful when working with a '--no-trees' repository

(see 'bzr help repositories').

If you want to have a working tree on a remote machine that you push to you

can either run 'bzr update' in the remote branch after each push, or use some

other method to update the tree during the push. There is an 'rspush' plugin

that will update the working tree using rsync as well as doing a push. There

is also a 'push-and-update' plugin that automates running 'bzr update' via SSH

after each push.

Useful commands::

  checkout     Create a working tree when a branch does not have one.

  remove-tree  Removes the working tree from a branch when it is safe to do so.

  update       When a working tree is out of sync with it's associated branch

               this will update the tree to match the branch.

"""

_branches = \

"""Branches

A branch consists of the state of a project, including all of its

history. All branches have a repository associated (which is where the

branch history is stored), but multiple branches may share the same

repository (a shared repository). Branches can be copied and merged.

Related commands::

  init    Change a directory into a versioned branch.

  branch  Create a new branch that is a copy of an existing branch.

  merge   Perform a three-way merge.

"""

_standalone_trees = \

"""Standalone Trees

A standalone tree is a working tree with an associated repository. It

is an independently usable branch, with no dependencies on any other.

Creating a standalone tree (via bzr init) is the quickest way to put

an existing project under version control.

Related Commands::

  init    Make a directory into a versioned branch.

"""

_status_flags = \

"""Status Flags

Status flags are used to summarise changes to the working tree in a concise

manner.  They are in the form::

   xxx   <filename>

where the columns' meanings are as follows.

Column 1 - versioning/renames::

  + File versioned

  - File unversioned

  R File renamed

  ? File unknown

  X File nonexistent (and unknown to bzr)

  C File has conflicts

  P Entry for a pending merge (not a file)

Column 2 - contents::

  N File created

  D File deleted

  K File kind changed

  M File modified

Column 3 - execute::

  * The execute bit was changed

"""

_env_variables = \

"""Environment Variables

================ =================================================================

BZRPATH          Path where bzr is to look for shell plugin external commands.

BZR_EMAIL        E-Mail address of the user. Overrides EMAIL.

EMAIL            E-Mail address of the user.

BZR_EDITOR       Editor for editing commit messages. Overrides EDITOR.

EDITOR           Editor for editing commit messages.

BZR_PLUGIN_PATH  Paths where bzr should look for plugins.

BZR_HOME         Directory holding .bazaar config dir. Overrides HOME.

BZR_HOME (Win32) Directory holding bazaar config dir. Overrides APPDATA and HOME.

BZR_REMOTE_PATH  Full name of remote 'bzr' command (for bzr+ssh:// URLs).

BZR_SSH          Path to SSH client, or one of paramiko, openssh, sshcorp, plink.

BZR_LOG          Location of .bzr.log (use '/dev/null' to suppress log).

BZR_LOG (Win32)  Location of .bzr.log (use 'NUL' to suppress log).

BZR_COLUMNS      Override implicit terminal width.

BZR_CONCURRENCY  Number of processes that can be run concurrently (selftest).

================ =================================================================

"""

_files = \

r"""Files

:On Linux:   ~/.bazaar/bazaar.conf

:On Windows: C:\\Documents and Settings\\username\\Application Data\\bazaar\\2.0\\bazaar.conf

Contains the user's default configuration. The section ``[DEFAULT]`` is

used to define general configuration that will be applied everywhere.

The section ``[ALIASES]`` can be used to create command aliases for

commonly used options.

A typical config file might look something like::

  [DEFAULT]

  email=John Doe <jdoe@isp.com>

  [ALIASES]

  commit = commit --strict

  log10 = log --short -r -10..-1

"""

_criss_cross = \

"""Criss-Cross

A criss-cross in the branch history can cause the default merge technique

to emit more conflicts than would normally be expected.

In complex merge cases, ``bzr merge --lca`` or ``bzr merge --weave`` may give

better results.  You may wish to ``bzr revert`` the working tree and merge

again.  Alternatively, use ``bzr remerge`` on particular conflicted files.

Criss-crosses occur in a branch's history if two branches merge the same thing

and then merge one another, or if two branches merge one another at the same

time.  They can be avoided by having each branch only merge from or into a

designated central branch (a "star topology").

Criss-crosses cause problems because of the way merge works.  Bazaar's default

merge is a three-way merger; in order to merge OTHER into THIS, it must

find a basis for comparison, BASE.  Using BASE, it can determine whether

differences between THIS and OTHER are due to one side adding lines, or

from another side removing lines.

Criss-crosses mean there is no good choice for a base.  Selecting the recent

merge points could cause one side's changes to be silently discarded.

Selecting older merge points (which Bazaar does) mean that extra conflicts

are emitted.

The ``weave`` merge type is not affected by this problem because it uses

line-origin detection instead of a basis revision to determine the cause of

differences.

"""

_branches_out_of_sync = """Branches out of sync

When reconfiguring a checkout, tree or branch into a lightweight checkout,

a local branch must be destroyed.  (For checkouts, this is the local branch

that serves primarily as a cache.)  If the branch-to-be-destroyed does not

have the same last revision as the new reference branch for the lightweight

checkout, data could be lost, so Bazaar refuses.

How you deal with this depends on *why* the branches are out of sync.

If you have a checkout and have done local commits, you can get back in sync

by running "bzr update" (and possibly "bzr commit").

If you have a branch and the remote branch is out-of-date, you can push

the local changes using "bzr push".  If the local branch is out of date, you

can do "bzr pull".  If both branches have had changes, you can merge, commit

and then push your changes.  If you decide that some of the changes aren't

useful, you can "push --overwrite" or "pull --overwrite" instead.

"""

_storage_formats = \

"""Storage Formats

To ensure that older clients do not access data incorrectly,

Bazaar's policy is to introduce a new storage format whenever

new features requiring new metadata are added. New storage

formats may also be introduced to improve performance and

scalability.

The newest format, 2a, is highly recommended. If your

project is not using 2a, then you should suggest to the

project owner to upgrade.

Note: Some of the older formats have two variants:

a plain one and a rich-root one. The latter include an additional

field about the root of the tree. There is no performance cost

for using a rich-root format but you cannot easily merge changes

from a rich-root format into a plain format. As a consequence,

moving a project to a rich-root format takes some co-ordination

in that all contributors need to upgrade their repositories

around the same time. 2a and all future formats will be

implicitly rich-root.

See ``bzr help current-formats`` for the complete list of

currently supported formats. See ``bzr help other-formats`` for

descriptions of any available experimental and deprecated formats.

"""

# Register help topics

topic_registry.register("revisionspec", _help_on_revisionspec,

                        "Explain how to use --revision")

topic_registry.register('basic', _basic_help, "Basic commands", SECT_HIDDEN)

topic_registry.register('topics', _help_on_topics, "Topics list", SECT_HIDDEN)

def get_current_formats_topic(topic):

    from bzrlib import bzrdir

    return "Current Storage Formats\n\n" + \

        bzrdir.format_registry.help_topic(topic)

def get_other_formats_topic(topic):

    from bzrlib import bzrdir

    return "Other Storage Formats\n\n" + \

        bzrdir.format_registry.help_topic(topic)

topic_registry.register('current-formats', get_current_formats_topic,

    'Current storage formats')

topic_registry.register('other-formats', get_other_formats_topic,

    'Experimental and deprecated storage formats')

topic_registry.register('standard-options', _standard_options,

                        'Options that can be used with any command')

topic_registry.register('global-options', _global_options,

                    'Options that control how Bazaar runs')

topic_registry.register('urlspec', _help_on_transport,

                        "Supported transport protocols")

topic_registry.register('status-flags', _status_flags,

                        "Help on status flags")

def get_bugs_topic(topic):

    from bzrlib import bugtracker

    return ("Bug Tracker Settings\n\n" +

        bugtracker.tracker_registry.help_topic(topic))

topic_registry.register('bugs', get_bugs_topic, 'Bug tracker settings')

topic_registry.register('env-variables', _env_variables,

                        'Environment variable names and values')

topic_registry.register('files', _files,

                        'Information on configuration and log files')

topic_registry.register_lazy('hooks', 'bzrlib.hooks', 'hooks_help_text',

                        'Points at which custom processing can be added')

# Load some of the help topics from files. Note that topics which reproduce API

# details will tend to skew (quickly usually!) so please seek other solutions

# for such things.

topic_registry.register('authentication', _load_from_file,

                        'Information on configuring authentication')

topic_registry.register('configuration', _load_from_file,

                        'Details on the configuration settings available')

topic_registry.register('conflicts', _load_from_file,

                        'Types of conflicts and what to do about them')

topic_registry.register('debug-flags', _load_from_file,

                        'Options to show or record debug information')

topic_registry.register('log-formats', _load_from_file,

                        'Details on the logging formats available')

topic_registry.register('diverged-branches', _load_from_file,

                        'How to fix diverged branches')

# Register concept topics.

# Note that we might choose to remove these from the online help in the

# future or implement them via loading content from files. In the meantime,

# please keep them concise.

topic_registry.register('branches', _branches,

                        'Information on what a branch is', SECT_CONCEPT)

topic_registry.register('checkouts', _checkouts,

                        'Information on what a checkout is', SECT_CONCEPT)

topic_registry.register('content-filters', _load_from_file,

                        'Conversion of content into/from working trees',

                        SECT_CONCEPT)

topic_registry.register('eol', _load_from_file,

                        'Information on end-of-line handling',

                        SECT_CONCEPT)

topic_registry.register('formats', _storage_formats,

                        'Information on choosing a storage format',

                        SECT_CONCEPT)

topic_registry.register('patterns', _load_from_file,

                        'Information on the pattern syntax',

                        SECT_CONCEPT)

topic_registry.register('repositories', _repositories,

                        'Basic information on shared repositories.',

                        SECT_CONCEPT)

topic_registry.register('rules', _load_from_file,

                        'Information on defining rule-based preferences',

                        SECT_CONCEPT)

topic_registry.register('standalone-trees', _standalone_trees,

                        'Information on what a standalone tree is',

                        SECT_CONCEPT)

topic_registry.register('working-trees', _working_trees,

                        'Information on working trees', SECT_CONCEPT)

topic_registry.register('criss-cross', _criss_cross,

                        'Information on criss-cross merging', SECT_CONCEPT)

topic_registry.register('sync-for-reconfigure', _branches_out_of_sync,

                        'Steps to resolve "out-of-sync" when reconfiguring',

                        SECT_CONCEPT)

class HelpTopicIndex(object):

    """A index for bzr help that returns topics."""

    def __init__(self):

        self.prefix = ''

    def get_topics(self, topic):

        """Search for topic in the HelpTopicRegistry.

        :param topic: A topic to search for. None is treated as 'basic'.

        :return: A list which is either empty or contains a single

            RegisteredTopic entry.

        """

        if topic is None:

            topic = 'basic'

        if topic in topic_registry:

            return [RegisteredTopic(topic)]

        else:

            return []

class RegisteredTopic(object):

    """A help topic which has been registered in the HelpTopicRegistry.

    These topics consist of nothing more than the name of the topic - all

    data is retrieved on demand from the registry.

    """

    def __init__(self, topic):

        """Constructor.

        :param topic: The name of the topic that this represents.

        """

        self.topic = topic