mercurial/utils/resourceutil.py

packaging: add support for PyOxidizer

I've successfully built Mercurial on the development tip of
PyOxidizer on Linux and Windows. It mostly "just works" on Linux.
Windows is a bit more finicky.

In-memory resource files are probably not all working correctly
due to bugs in PyOxidizer's naming of modules. PyOxidizer now
now supports installing files next to the produced binary. (We
do this for templates in the added file.) So a workaround
should be available.

Also, since the last time I submitted support for PyOxidizer,
PyOxidizer gained the ability to auto-generate Rust projects
to build executables. So we don't need to worry about vendoring
any Rust code to initially support PyOxidizer. However, at some
point we will likely want to write our own command line driver
that embeds a Python interpreter via PyOxidizer so we can run
Rust code outside the confines of a Python interpreter. But that
will be a follow-up.

I would also like to add packaging.py CLI commands to build
PyOxidizer distributions. This can come later, if ever.
PyOxidizer's new "targets" feature makes it really easy to define
packaging tasks in its Starlark configuration file. While not
much is implemented yet, eventually we should be able to produce
MSIs, etc using a `pyoxidizer build` one-liner. We'll get there...

Differential Revision: https://phab.mercurial-scm.org/D7450

# resourceutil.py - utility for looking up resources
#
#  Copyright 2005 K. Thananchayan <[e-mail]>
#  Copyright 2005-2007 Matt Mackall <[e-mail]>
#  Copyright 2006 Vadim Gelfer <[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.

from __future__ import absolute_import

import imp
import os
import sys

from .. import pycompat


def mainfrozen():
    """return True if we are a frozen executable.

    The code supports py2exe (most common, Windows only) and tools/freeze
    (portable, not much used).
    """
    return (
        pycompat.safehasattr(sys, "frozen")
        or pycompat.safehasattr(sys, "importers")  # new py2exe
        or imp.is_frozen("__main__")  # old py2exe
    )  # tools/freeze


# the location of data files matching the source code
if mainfrozen() and getattr(sys, 'frozen', None) != 'macosx_app':
    # executable version (py2exe) doesn't support __file__
    datapath = os.path.dirname(pycompat.sysexecutable)
    _rootpath = os.path.dirname(datapath)
else:
    datapath = os.path.dirname(os.path.dirname(pycompat.fsencode(__file__)))
    _rootpath = os.path.dirname(datapath)

try:
    from importlib import resources

    from .. import encoding

    # Force loading of the resources module
    resources.open_binary  # pytype: disable=module-attr

    def open_resource(package, name):
        return resources.open_binary(  # pytype: disable=module-attr
            pycompat.sysstr(package), pycompat.sysstr(name)
        )

    def is_resource(package, name):
        return resources.is_resource(
            pycompat.sysstr(package), encoding.strfromlocal(name)
        )

    def contents(package):
        for r in resources.contents(pycompat.sysstr(package)):
            yield encoding.strtolocal(r)


except (ImportError, AttributeError):

    def _package_path(package):
        return os.path.join(_rootpath, *package.split(b'.'))

    def open_resource(package, name):
        path = os.path.join(_package_path(package), name)
        return open(path, 'rb')

    def is_resource(package, name):
        path = os.path.join(_package_path(package), name)

        try:
            return os.path.isfile(pycompat.fsdecode(path))
        except (IOError, OSError):
            return False

    def contents(package):
        path = pycompat.fsdecode(_package_path(package))

        for p in os.listdir(path):
            yield pycompat.fsencode(p)