~bzr-pqm/bzr/bzr.dev

#! /usr/bin/python

# Copyright (C) 2005 Canonical Ltd

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

# Author: Martin Pool <mbp@canonical.com>

import os

import errno

from bzrlib.weavefile import read_weave, write_weave_v5

from bzrlib.weave import Weave

from bzrlib.atomicfile import AtomicFile

class WeaveStore(object):

    """Collection of several weave files in a directory.

    This has some shortcuts for reading and writing them.

    """

    def __init__(self, dir, get_file=None):

        self._dir = dir

        self._cache = {}

        self.enable_cache = False

        if get_file is not None:

            self.get_file = get_file

    def get_file(self, filename):

        return file(filename, 'rb')

    def filename(self, file_id):

        return self._dir + os.sep + file_id + '.weave'

    def get_weave(self, file_id):

        if self.enable_cache:

            if file_id in self._cache:

                return self._cache[file_id]

        w = read_weave(self.get_file(self.filename(file_id)))

        if self.enable_cache:

            self._cache[file_id] = w

        return w

    def get_lines(self, file_id, rev_id):

        """Return text from a particular version of a weave.

        Returned as a list of lines."""

        w = self.get_weave(file_id)

        return w.get(w.lookup(rev_id))

    def get_weave_or_empty(self, file_id):

        """Return a weave, or an empty one if it doesn't exist.""" 

        try:

            inf = self.get_file(self.filename(file_id))

        except IOError, e:

            if e.errno == errno.ENOENT:

                return Weave(weave_name=file_id)

            else:

                raise

        else:

            return read_weave(inf)

    def put_empty_weave(self, file_id):

        self.put_weave(file_id, Weave())

    def put_weave(self, file_id, weave):

        """Write back a modified weave"""

        if self.enable_cache:

            self._cache[file_id] = weave

        weave_fn = self.filename(file_id)

        af = AtomicFile(weave_fn)

        try:

            write_weave_v5(weave, af)

            af.commit()

        finally:

            af.close()

    def add_text(self, file_id, rev_id, new_lines, parents):

        w = self.get_weave_or_empty(file_id)

        parent_idxs = map(w.lookup, parents)

        w.add(rev_id, parent_idxs, new_lines)

        self.put_weave(file_id, w)