contrib/debugshell.py

absorb: preserve changesets which were already empty

Most commands in Mercurial (commit, rebase, absorb itself) don’t create empty
changesets or drop them if they become empty. If there’s a changeset that’s
empty, it must be a deliberate choice of the user. At least it shouldn’t be
absorb’s responsibility to prune them. The fact that changesets that became
empty during absorb are pruned, is unaffected by this.

This case was found while writing patches which make it possible to configure
absorb and rebase to not drop empty changesets. Even without having such config
set, I think it’s valuable to preserve changesets which were already empty.

# debugshell extension
"""a python shell with repo, changelog & manifest objects"""

from __future__ import absolute_import
import code
import mercurial
import sys
from mercurial import (
    demandimport,
    pycompat,
    registrar,
)

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


def pdb(ui, repo, msg, **opts):
    objects = {
        'mercurial': mercurial,
        'repo': repo,
        'cl': repo.changelog,
        'mf': repo.manifestlog,
    }

    code.interact(msg, local=objects)


def ipdb(ui, repo, msg, **opts):
    import IPython

    cl = repo.changelog
    mf = repo.manifestlog
    cl, mf  # use variables to appease pyflakes

    IPython.embed()


@command(b'debugshell|dbsh', [])
def debugshell(ui, repo, **opts):
    bannermsg = "loaded repo : %s\n" "using source: %s" % (
        pycompat.sysstr(repo.root),
        mercurial.__path__[0],
    )

    pdbmap = {'pdb': 'code', 'ipdb': 'IPython'}

    debugger = ui.config(b"ui", b"debugger")
    if not debugger:
        debugger = 'pdb'
    else:
        debugger = pycompat.sysstr(debugger)

    # if IPython doesn't exist, fallback to code.interact
    try:
        with demandimport.deactivated():
            __import__(pdbmap[debugger])
    except ImportError:
        ui.warnnoi18n(
            b"%s debugger specified but %s module was not found\n"
            % (debugger, pdbmap[debugger])
        )
        debugger = b'pdb'

    getattr(sys.modules[__name__], debugger)(ui, repo, bannermsg, **opts)