hgext/lfs/pointer.py

templater: add context.preload(t) to test if the specified template exists

I'm going to remove 'templ' from the resources dict because it is the only
resource that the caller can't provide. This also implies that putting
'templ' into the resources dict creates a reference cycle.

context.preload(t) will be used in place of templater.__contains__().

# pointer.py - Git-LFS pointer serialization
#
# Copyright 2017 Facebook, Inc.
#
# 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 re

from mercurial.i18n import _

from mercurial import (
    error,
    pycompat,
)

class InvalidPointer(error.RevlogError):
    pass

class gitlfspointer(dict):
    VERSION = 'https://git-lfs.github.com/spec/v1'

    def __init__(self, *args, **kwargs):
        self['version'] = self.VERSION
        super(gitlfspointer, self).__init__(*args)
        self.update(pycompat.byteskwargs(kwargs))

    @classmethod
    def deserialize(cls, text):
        try:
            return cls(l.split(' ', 1) for l in text.splitlines()).validate()
        except ValueError: # l.split returns 1 item instead of 2
            raise InvalidPointer(_('cannot parse git-lfs text: %r') % text)

    def serialize(self):
        sortkeyfunc = lambda x: (x[0] != 'version', x)
        items = sorted(self.validate().iteritems(), key=sortkeyfunc)
        return ''.join('%s %s\n' % (k, v) for k, v in items)

    def oid(self):
        return self['oid'].split(':')[-1]

    def size(self):
        return int(self['size'])

    # regular expressions used by _validate
    # see https://github.com/git-lfs/git-lfs/blob/master/docs/spec.md
    _keyre = re.compile(br'\A[a-z0-9.-]+\Z')
    _valuere = re.compile(br'\A[^\n]*\Z')
    _requiredre = {
        'size': re.compile(br'\A[0-9]+\Z'),
        'oid': re.compile(br'\Asha256:[0-9a-f]{64}\Z'),
        'version': re.compile(br'\A%s\Z' % re.escape(VERSION)),
    }

    def validate(self):
        """raise InvalidPointer on error. return self if there is no error"""
        requiredcount = 0
        for k, v in self.iteritems():
            if k in self._requiredre:
                if not self._requiredre[k].match(v):
                    raise InvalidPointer(_('unexpected value: %s=%r') % (k, v))
                requiredcount += 1
            elif not self._keyre.match(k):
                raise InvalidPointer(_('unexpected key: %s') % k)
            if not self._valuere.match(v):
                raise InvalidPointer(_('unexpected value: %s=%r') % (k, v))
        if len(self._requiredre) != requiredcount:
            miss = sorted(set(self._requiredre.keys()).difference(self.keys()))
            raise InvalidPointer(_('missed keys: %s') % ', '.join(miss))
        return self

deserialize = gitlfspointer.deserialize