view hgext/git/gitutil.py @ 50411:841b13e6e84c

rust-changelog: introducing an intermediate `ChangelogEntry`

Before this change, client code needing to extract, e.g, the Node ID and the
description from a changeset had no other choice than calling both
`entry_for_rev()` and `data_for_rev()`. This duplicates some (limited) computation, and
more importantly imposes bad hygiene for client code: at some point of developement,
the client code would have to pass over both entry and data in its internal layers,
which at some point of development would raise the question whether they are consistent.

We introduce the intermediate `ChangelogEntry` from which both conversion to the generic
`RevlogEntry` and extraction of `ChangelogRevisionData` are possible.
It might grow some convenience methods in the future.

We keep the `data_for_rev()` method of `Changelog` for compatibility, pointing users at the more
powerful alternative.

"""utilities to assist in working with pygit2"""

from mercurial.node import bin, sha1nodeconstants

pygit2_module = None


def get_pygit2():
    global pygit2_module
    if pygit2_module is None:
        try:
            import pygit2 as pygit2_module  # pytype: disable=import-error

            pygit2_module.InvalidSpecError
        except (ImportError, AttributeError):
            pass
    return pygit2_module


def pygit2_version():
    mod = get_pygit2()
    v = "N/A"

    if mod:
        try:
            v = mod.__version__
        except AttributeError:
            pass

    return b"(pygit2 %s)" % v.encode("utf-8")


def togitnode(n):
    """Wrapper to convert a Mercurial binary node to a unicode hexlified node.

    pygit2 and sqlite both need nodes as strings, not bytes.
    """
    assert len(n) == 20
    return n.hex()


def fromgitnode(n):
    """Opposite of togitnode."""
    assert len(n) == 40
    return bin(n)


nullgit = togitnode(sha1nodeconstants.nullid)