view doc/runrst @ 46108:bdc2bf68f19e

mergetools: add new conflict marker format with diffs in

I use 3-way conflict markers. Often when I resolve them, I manually
compare one the base with one side and apply the differences to the
other side. That can be hard when the conflict marker is large. This
patch introduces a new type of conflict marker, which I'm hoping will
make it easier to resolve conflicts.

The new format uses `<<<<<<<` and `>>>>>>>` to open and close the
markers, just like our existing 2-way and 3-way conflict
markers. Instead of having 2 or 3 snapshots (left+right or
left+base+right), it has a sequence of diffs. A diff looks like this:

```
------- base
+++++++ left
 a
-b
+c
 d
```

A diff that adds one side ("diff from nothing") has a `=======` header
instead and does not have have `+` prefixed on its lines. A regular
3-way merge can be viewed as adding one side plus a diff between the
base and the other side. It thus has two ways of being represented,
depending on which side is being diffed:

```
<<<<<<<
======= left
contents
on
left
------- base
+++++++ right
 contents
 on
-left
+right
>>>>>>>
```
or
```
<<<<<<<
------- base
+++++++ left
 contents
 on
-right
+left
======= right
contents
on
right
>>>>>>>
```

I've made it so the new merge tool tries to pick a version that has
the most common lines (no difference in the example above).


I've called the new tool "mergediff" to stick to the convention of
starting with "merge" if the tool tries a regular 3-way merge.

The idea came from my pet VCS (placeholder name `jj`), which has
support for octopus merges and other ways of ending up with merges of
more than 3 versions. I wanted to be able to represent such conflicts
in the working copy and therefore thought of this format (although I
have not yet implemented it in my VCS). I then attended a meeting with
Larry McVoy, who said BitKeeper has an option (`bk smerge -g`) for
showing a similar format, which reminded me to actually attempt this
in Mercurial.

Differential Revision: https://phab.mercurial-scm.org/D9551

#!/usr/bin/env python3
#
# runrst - register custom roles and run correct writer
#
# Copyright 2010 Matt Mackall <[e-mail]> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

"""usage: %s WRITER args...

where WRITER is the name of a Docutils writer such as 'html' or 'manpage'
"""

from __future__ import absolute_import

import sys

try:
    import docutils.core as core
    import docutils.nodes as nodes
    import docutils.utils as utils
    import docutils.parsers.rst.roles as roles
except ImportError:
    sys.stderr.write(
        "abort: couldn't generate documentation: docutils "
        "module is missing\n"
    )
    sys.stderr.write(
        "please install python-docutils or see "
        "http://docutils.sourceforge.net/\n"
    )
    sys.exit(-1)


def role_hg(name, rawtext, text, lineno, inliner, options=None, content=None):
    text = "hg " + utils.unescape(text)
    linktext = nodes.literal(rawtext, text)
    parts = text.split()
    cmd, args = parts[1], parts[2:]
    refuri = "hg.1.html#%s" % cmd
    if cmd == 'help' and args:
        if args[0] == 'config':
            # :hg:`help config`
            refuri = "hgrc.5.html"
        elif args[0].startswith('config.'):
            # :hg:`help config.SECTION...`
            refuri = "hgrc.5.html#%s" % args[0].split('.', 2)[1]
        elif len(args) >= 2 and args[0] == '-c':
            # :hg:`help -c COMMAND ...` is equivalent to :hg:`COMMAND`
            # (mainly for :hg:`help -c config`)
            refuri = "hg.1.html#%s" % args[1]
        else:
            refuri = "hg.1.html#%s" % args[0]
    node = nodes.reference(rawtext, '', linktext, refuri=refuri)
    return [node], []


roles.register_local_role("hg", role_hg)

if __name__ == "__main__":
    if len(sys.argv) < 2:
        sys.stderr.write(__doc__ % sys.argv[0])
        sys.exit(1)

    writer = sys.argv[1]
    del sys.argv[1]

    core.publish_cmdline(writer_name=writer)