hgext/convert/darcs.py

match: express anypats(), not prefix(), in terms of the others

When I added prefix() in 9789b4a7c595 (match: introduce boolean
prefix() method, 2014-10-28), we already had always(), isexact(), and
anypats(), so it made sense to write it in terms of them (a prefix
matcher is one that isn't any of the other types). It's only now that
I realize that it's much more natural to define prefix() explicitly
(it's one that uses path: patterns, roughly speaking) and let
anypats() be defined in terms of the others. Remember that these
methods are all used for determining which fast paths are
possible. anypats() simply means that no fast paths are possible (it
could be called complex() instead). Further evidence is that
rootfilesin:some/dir does not have any patterns, but it's still
considered to be an anypats() matcher. That's because anypats() really
just means that it's not a prefix() matcher (and not always() and not
isexact()).

This patch thus changes prefix() to return False by default and
anypats() to return True only if the other three are False. Having
anypats() be True by default also seems like a good thing, because it
means forgetting to override it will lead only to performance bugs,
not correctness bugs.

Since the base class's implementation changes, we're also forced to
update the subclasses. That change exposed and fixed a bug in the
differencematcher: for example when both its two input matchers were
prefix matchers, we would say that the result was also a prefix
matcher, which is incorrect, because e.g "path:dir - path:dir/foo" no
longer matches everything under "dir" (which is what prefix() means).

# darcs.py - darcs support for the convert extension
#
#  Copyright 2007-2009 Matt Mackall <[e-mail]> and others
#
# 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 errno
import os
import re
import shutil
import tempfile
from mercurial.i18n import _
from mercurial import (
    error,
    util,
)
from . import common
NoRepo = common.NoRepo

# The naming drift of ElementTree is fun!

try:
    import xml.etree.cElementTree.ElementTree as ElementTree
    import xml.etree.cElementTree.XMLParser as XMLParser
except ImportError:
    try:
        import xml.etree.ElementTree.ElementTree as ElementTree
        import xml.etree.ElementTree.XMLParser as XMLParser
    except ImportError:
        try:
            import elementtree.cElementTree.ElementTree as ElementTree
            import elementtree.cElementTree.XMLParser as XMLParser
        except ImportError:
            try:
                import elementtree.ElementTree.ElementTree as ElementTree
                import elementtree.ElementTree.XMLParser  as XMLParser
            except ImportError:
                pass

class darcs_source(common.converter_source, common.commandline):
    def __init__(self, ui, path, revs=None):
        common.converter_source.__init__(self, ui, path, revs=revs)
        common.commandline.__init__(self, ui, 'darcs')

        # check for _darcs, ElementTree so that we can easily skip
        # test-convert-darcs if ElementTree is not around
        if not os.path.exists(os.path.join(path, '_darcs')):
            raise NoRepo(_("%s does not look like a darcs repository") % path)

        common.checktool('darcs')
        version = self.run0('--version').splitlines()[0].strip()
        if version < '2.1':
            raise error.Abort(_('darcs version 2.1 or newer needed (found %r)')
                              % version)

        if "ElementTree" not in globals():
            raise error.Abort(_("Python ElementTree module is not available"))

        self.path = os.path.realpath(path)

        self.lastrev = None
        self.changes = {}
        self.parents = {}
        self.tags = {}

        # Check darcs repository format
        format = self.format()
        if format:
            if format in ('darcs-1.0', 'hashed'):
                raise NoRepo(_("%s repository format is unsupported, "
                               "please upgrade") % format)
        else:
            self.ui.warn(_('failed to detect repository format!'))

    def before(self):
        self.tmppath = tempfile.mkdtemp(
            prefix='convert-' + os.path.basename(self.path) + '-')
        output, status = self.run('init', repodir=self.tmppath)
        self.checkexit(status)

        tree = self.xml('changes', xml_output=True, summary=True,
                        repodir=self.path)
        tagname = None
        child = None
        for elt in tree.findall('patch'):
            node = elt.get('hash')
            name = elt.findtext('name', '')
            if name.startswith('TAG '):
                tagname = name[4:].strip()
            elif tagname is not None:
                self.tags[tagname] = node
                tagname = None
            self.changes[node] = elt
            self.parents[child] = [node]
            child = node
        self.parents[child] = []

    def after(self):
        self.ui.debug('cleaning up %s\n' % self.tmppath)
        shutil.rmtree(self.tmppath, ignore_errors=True)

    def recode(self, s, encoding=None):
        if isinstance(s, unicode):
            # XMLParser returns unicode objects for anything it can't
            # encode into ASCII. We convert them back to str to get
            # recode's normal conversion behavior.
            s = s.encode('latin-1')
        return super(darcs_source, self).recode(s, encoding)

    def xml(self, cmd, **kwargs):
        # NOTE: darcs is currently encoding agnostic and will print
        # patch metadata byte-for-byte, even in the XML changelog.
        etree = ElementTree()
        # While we are decoding the XML as latin-1 to be as liberal as
        # possible, etree will still raise an exception if any
        # non-printable characters are in the XML changelog.
        parser = XMLParser(encoding='latin-1')
        p = self._run(cmd, **kwargs)
        etree.parse(p.stdout, parser=parser)
        p.wait()
        self.checkexit(p.returncode)
        return etree.getroot()

    def format(self):
        output, status = self.run('show', 'repo', no_files=True,
                                  repodir=self.path)
        self.checkexit(status)
        m = re.search(r'^\s*Format:\s*(.*)$', output, re.MULTILINE)
        if not m:
            return None
        return ','.join(sorted(f.strip() for f in m.group(1).split(',')))

    def manifest(self):
        man = []
        output, status = self.run('show', 'files', no_directories=True,
                                  repodir=self.tmppath)
        self.checkexit(status)
        for line in output.split('\n'):
            path = line[2:]
            if path:
                man.append(path)
        return man

    def getheads(self):
        return self.parents[None]

    def getcommit(self, rev):
        elt = self.changes[rev]
        date = util.strdate(elt.get('local_date'), '%a %b %d %H:%M:%S %Z %Y')
        desc = elt.findtext('name') + '\n' + elt.findtext('comment', '')
        # etree can return unicode objects for name, comment, and author,
        # so recode() is used to ensure str objects are emitted.
        return common.commit(author=self.recode(elt.get('author')),
                             date=util.datestr(date, '%Y-%m-%d %H:%M:%S %1%2'),
                             desc=self.recode(desc).strip(),
                             parents=self.parents[rev])

    def pull(self, rev):
        output, status = self.run('pull', self.path, all=True,
                                  match='hash %s' % rev,
                                  no_test=True, no_posthook=True,
                                  external_merge='/bin/false',
                                  repodir=self.tmppath)
        if status:
            if output.find('We have conflicts in') == -1:
                self.checkexit(status, output)
            output, status = self.run('revert', all=True, repodir=self.tmppath)
            self.checkexit(status, output)

    def getchanges(self, rev, full):
        if full:
            raise error.Abort(_("convert from darcs does not support --full"))
        copies = {}
        changes = []
        man = None
        for elt in self.changes[rev].find('summary').getchildren():
            if elt.tag in ('add_directory', 'remove_directory'):
                continue
            if elt.tag == 'move':
                if man is None:
                    man = self.manifest()
                source, dest = elt.get('from'), elt.get('to')
                if source in man:
                    # File move
                    changes.append((source, rev))
                    changes.append((dest, rev))
                    copies[dest] = source
                else:
                    # Directory move, deduce file moves from manifest
                    source = source + '/'
                    for f in man:
                        if not f.startswith(source):
                            continue
                        fdest = dest + '/' + f[len(source):]
                        changes.append((f, rev))
                        changes.append((fdest, rev))
                        copies[fdest] = f
            else:
                changes.append((elt.text.strip(), rev))
        self.pull(rev)
        self.lastrev = rev
        return sorted(changes), copies, set()

    def getfile(self, name, rev):
        if rev != self.lastrev:
            raise error.Abort(_('internal calling inconsistency'))
        path = os.path.join(self.tmppath, name)
        try:
            data = util.readfile(path)
            mode = os.lstat(path).st_mode
        except IOError as inst:
            if inst.errno == errno.ENOENT:
                return None, None
            raise
        mode = (mode & 0o111) and 'x' or ''
        return data, mode

    def gettags(self):
        return self.tags