view hgext/show.py @ 31793:69d8fcf20014

help: document bundle specifications

I softly formalized the concept of a "bundle specification" a while
ago when I was working on clone bundles and stream clone bundles and
wanted a more robust way to define what exactly is in a bundle file.

The concept has existed for a while. Since it is part of the clone
bundles feature and exposed to the user via the "-t" argument to
`hg bundle`, it is something we need to support for the long haul.

After the 4.1 release, I heard a few people comment that they didn't
realize you could generate zstd bundles with `hg bundle`. I'm
partially to blame for not documenting it in bundle's docstring.

Additionally, I added a hacky, experimental feature for controlling
the compression level of bundles in 76104a4899ad. As the commit
message says, I went with a quick and dirty solution out of time
constraints. Furthermore, I wanted to eventually store this
configuration in the "bundlespec" so it could be made more flexible.

Given:

a) bundlespecs are here to stay
b) we don't have great documentation over what they are, despite being
   a user-facing feature
c) the list of available compression engines and their behavior isn't
   exposed
d) we need an extensible place to modify behavior of compression
   engines

I want to move forward with formalizing bundlespecs as a user-facing
feature. This commit does that by introducing a "bundlespec" help
page. Leaning on the just-added compression engine documentation
and API, the topic also conveniently lists available compression
engines and details about them. This makes features like zstd
bundle compression more discoverable. e.g. you can now
`hg help -k zstd` and it lists the "bundlespec" topic.

# show.py - Extension implementing `hg show`
#
# Copyright 2017 Gregory Szorc <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

"""unified command to show various repository information (EXPERIMENTAL)

This extension provides the :hg:`show` command, which provides a central
command for displaying commonly-accessed repository data and views of that
data.
"""

from __future__ import absolute_import

from mercurial.i18n import _
from mercurial import (
    cmdutil,
    commands,
    error,
    registrar,
)

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'

cmdtable = {}
command = cmdutil.command(cmdtable)

class showcmdfunc(registrar._funcregistrarbase):
    """Register a function to be invoked for an `hg show <thing>`."""

    # Used by _formatdoc().
    _docformat = '%s -- %s'

    def _extrasetup(self, name, func, fmtopic=None):
        """Called with decorator arguments to register a show view.

        ``name`` is the sub-command name.

        ``func`` is the function being decorated.

        ``fmtopic`` is the topic in the style that will be rendered for
        this view.
        """
        func._fmtopic = fmtopic

showview = showcmdfunc()

@command('show', commands.formatteropts, _('VIEW'))
def show(ui, repo, view=None, template=None):
    """show various repository information

    A requested view of repository data is displayed.

    If no view is requested, the list of available views is shown and the
    command aborts.

    .. note::

       There are no backwards compatibility guarantees for the output of this
       command. Output may change in any future Mercurial release.

       Consumers wanting stable command output should specify a template via
       ``-T/--template``.

    List of available views:

    """
    if ui.plain() and not template:
        raise error.Abort(_('"hg show" cannot be used in plain mode because '
                            'output is not stable'),
                          hint=_('unset HGPLAIN and invoke with -T/--template '
                                 'to control output'))

    views = showview._table

    if not view:
        ui.pager('show')
        # TODO consider using formatter here so available views can be
        # rendered to custom format.
        ui.write(_('available views:\n'))
        ui.write('\n')

        for name, func in sorted(views.items()):
            ui.write(('%s\n') % func.__doc__)

        ui.write('\n')
        raise error.Abort(_('no view requested'),
                          hint=_('use "hg show VIEW" to choose a view'))

    # TODO use same logic as dispatch to perform prefix matching.
    if view not in views:
        raise error.Abort(_('unknown view: %s') % view,
                          hint=_('run "hg show" to see available views'))

    template = template or 'show'
    fmtopic = 'show%s' % views[view]._fmtopic

    ui.pager('show')
    with ui.formatter(fmtopic, {'template': template}) as fm:
        return views[view](ui, repo, fm)

@showview('bookmarks', fmtopic='bookmarks')
def showbookmarks(ui, repo, fm):
    """bookmarks and their associated changeset"""
    marks = repo._bookmarks
    if not len(marks):
        # TODO json output is corrupted; consider using formatter
        ui.write(_('(no bookmarks set)\n'))
        return

    active = repo._activebookmark
    longestname = max(len(b) for b in marks)
    # TODO consider exposing longest shortest(node).

    for bm, node in sorted(marks.items()):
        fm.startitem()
        fm.context(ctx=repo[node])
        fm.write('bookmark', '%s', bm)
        fm.write('node', fm.hexfunc(node), fm.hexfunc(node))
        fm.data(active=bm == active,
                longestbookmarklen=longestname)

# Adjust the docstring of the show command so it shows all registered views.
# This is a bit hacky because it runs at the end of module load. When moved
# into core or when another extension wants to provide a view, we'll need
# to do this more robustly.
# TODO make this more robust.
longest = max(map(len, showview._table.keys()))
for key in sorted(showview._table.keys()):
    cmdtable['show'][0].__doc__ += ' %s   %s\n' % (
        key.ljust(longest), showview._table[key]._origdoc)