hgext/largefiles/localstore.py

match: introduce boolean prefix() method

tl;dr: This is another step towards a (previously unstated) goal of
eliminating match.files() in conditions.

There are four types of matchers:

 * always: Matches everything, checked with always(), files() is empty

 * exact: Matches exact set of files, checked with isexact(), files()
   contains the files to match

 * patterns: Matches more complex patterns, checked with anypats(),
   files() contains roots of the matched patterns

 * prefix: Matches simple 'path:' patterns as prefixes ('foo' matches
   both 'foo' and 'foo/bar'), no single method to check, files()
   contains the prefixes to match

For completeness, it would be nice to have a method for checking for
the "prefix" type of matcher as well, so let's add that, making it
return True simply when none of the others do.

The larger goal here is to eliminate uses of match.files() in
conditions (i.e. bool(match.files())). The reason for this is that
there are scenarios when you would like to create a "prefix" matcher
that happens to match no files. One example is for 'hg files -I foo
bar'. The narrowmatcher also restricts the set of files given and it
would not surprise me if have bugs caused by that already. Note that
'if m.files() and not m.anypats()' and similar is sometimes used to
catch the "exact" and "prefix" cases above.

# Copyright 2009-2010 Gregory P. Ward
# Copyright 2009-2010 Intelerad Medical Systems Incorporated
# Copyright 2010-2011 Fog Creek Software
# Copyright 2010-2011 Unity Technologies
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''store class for local filesystem'''

from mercurial.i18n import _

import lfutil
import basestore

class localstore(basestore.basestore):
    '''localstore first attempts to grab files out of the store in the remote
    Mercurial repository.  Failing that, it attempts to grab the files from
    the user cache.'''

    def __init__(self, ui, repo, remote):
        self.remote = remote.local()
        super(localstore, self).__init__(ui, repo, self.remote.url())

    def put(self, source, hash):
        if lfutil.instore(self.remote, hash):
            return
        lfutil.link(source, lfutil.storepath(self.remote, hash))

    def exists(self, hashes):
        retval = {}
        for hash in hashes:
            retval[hash] = lfutil.instore(self.remote, hash)
        return retval


    def _getfile(self, tmpfile, filename, hash):
        path = lfutil.findfile(self.remote, hash)
        if not path:
            raise basestore.StoreError(filename, hash, self.url,
                _("can't get file locally"))
        fd = open(path, 'rb')
        try:
            return lfutil.copyandhash(fd, tmpfile)
        finally:
            fd.close()

    def _verifyfile(self, cctx, cset, contents, standin, verified):
        filename = lfutil.splitstandin(standin)
        if not filename:
            return False
        fctx = cctx[standin]
        key = (filename, fctx.filenode())
        if key in verified:
            return False

        expecthash = fctx.data()[0:40]
        storepath, exists = lfutil.findstorepath(self.remote, expecthash)
        verified.add(key)
        if not exists:
            self.ui.warn(
                _('changeset %s: %s references missing %s\n')
                % (cset, filename, storepath))
            return True                 # failed

        if contents:
            actualhash = lfutil.hashfile(storepath)
            if actualhash != expecthash:
                self.ui.warn(
                    _('changeset %s: %s references corrupted %s\n')
                    % (cset, filename, storepath))
                return True             # failed
        return False