/brz/remove-bazaar

#! /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>

"""knit - a weave-like structure"""

# TODO: Perhaps have copy and comparison methods?

class VerInfo(object):

    included = frozenset()

    def __init__(self, included=None):

        if included:

            self.included = frozenset(included)

    def __repr__(self):

        s = self.__class__.__name__ + '('

        if self.included:

            s += 'included=%r' % (list(self.included))

        s += ')'

        return s

class Knit(object):

    """knit - versioned text file storage.

    A Knit manages versions of line-based text files, keeping track of the

    originating version for each line.

    Texts can be identified in either of two ways:

    * a nonnegative index number.

    * a version-id string.

    Typically the index number will be valid only inside this knit and

    the version-id is used to reference it in the larger world.

    _l

        List of edit instructions.

        Each line is stored as a tuple of (index-id, text).  The line

        is present in the version equal to index-id.

    _v

        List of versions, indexed by index number.

        For each version we store the tuple (included_versions), which

        lists the previous versions also considered active.

    """

    def __init__(self):

        self._l = []

        self._v = []

    def add(self, parents, text):

        """Add a single text on top of the weave.

        Returns the index number of the newly added version.

        parents

            List or set of parent version numbers.

        text

            Sequence of lines to be added in the new version."""

        if not isinstance(text, list):

            raise ValueError("text should be a list, not %s" % type(text))

        self._check_versions(parents)

        idx = len(self._v)

        if parents:

            parents = frozenset(parents)

            delta = self._delta(parents, text)

            # offset gives the number of lines that have been inserted

            # into the weave up to the current point; if the original edit instruction

            # says to change line A then we actually change (A+offset)

            offset = 0

            for i1, i2, newlines in delta:

                assert 0 <= i1

                assert i1 <= i2

                assert i2 <= len(self._l)

                if i1 != i2:

                    raise NotImplementedError("can't handle replacing weave [%d:%d] yet"

                                              % (i1, i2))

                for line in newlines:

                    self._l.insert(i1 + offset, (idx, line))

                    offset += 1

            self._v.append(VerInfo(parents))

        else:

            # special case; adding with no parents revision; can do this

            # more quickly by just appending unconditionally

            for line in text:

                self._l.append((idx, line))

            self._v.append(VerInfo())

        return idx

    def _check_versions(self, indexes):

        """Check everything in the sequence of indexes is valid"""

        for i in indexes:

            try:

                self._v[i]

            except IndexError:

                raise IndexError("invalid version number %r" % i)

    def annotate(self, index):

        return list(self.annotate_iter(index))

    def annotate_iter(self, index):

        """Yield list of (index-id, line) pairs for the specified version.

        The index indicates when the line originated in the weave."""

        try:

            vi = self._v[index]

        except IndexError:

            raise IndexError('version index %d out of range' % index)

        included = set(vi.included)

        included.add(index)

        return iter(self._extract(included))

    def _extract(self, included):

        """Yield annotation of lines in included set.

        The set typically but not necessarily corresponds to a version.

        """

        for origin, line in self._l:

            if origin in included:

                yield origin, line

    def getiter(self, index):

        """Yield lines for the specified version."""

        for origin, line in self.annotate_iter(index):

            yield line

    def get(self, index):

        return list(self.getiter(index))

    def dump(self, to_file):

        from pprint import pprint

        print >>to_file, "Knit._l = ",

        pprint(self._l, to_file)

        print >>to_file, "Knit._v = ",

        pprint(self._v, to_file)

    def check(self):

        for vers_info in self._v:

            included = set()

            for vi in vers_info[0]:

                if vi < 0 or vi >= index:

                    raise ValueError("invalid included version %d for index %d"

                                     % (vi, index))

                if vi in included:

                    raise ValueError("repeated included version %d for index %d"

                                     % (vi, index))

                included.add(vi)

    def _delta(self, included, lines):

        """Return changes from basis to new revision.

        The old text for comparison is the union of included revisions.

        This is used in inserting a new text.

        Delta is returned as a sequence of (line1, line2, newlines),

        indicating that line1 through line2 of the old weave should be

        replaced by the sequence of lines in newlines.  Note that

        these line numbers are positions in the total weave and don't

        correspond to the lines in any extracted version, or even the

        extracted union of included versions.

        If line1=line2, this is a pure insert; if newlines=[] this is a

        pure delete.  (Similar to difflib.)

        """

        self._check_versions(included)

        ##from pprint import pprint

        # first get basis for comparison

        # basis holds (lineno, origin, line)

        basis = []

        ##print 'my lines:'

        ##pprint(self._l)

        lineno = 0

        for origin, line in self._l:

            if origin in included:

                basis.append((lineno, line))

            lineno += 1

        assert lineno == len(self._l)

        # now make a parallel list with only the text, to pass to the differ

        basis_lines = [line for (lineno, line) in basis]

        # add a sentinal, because we can also match against the final line

        basis.append((len(self._l), None))

        # XXX: which line of the weave should we really consider matches the end of the file?

        # the current code says it's the last line of the weave?

        from difflib import SequenceMatcher

        s = SequenceMatcher(None, basis_lines, lines)

        ##print 'basis sequence:'

        ##pprint(basis)

        for tag, i1, i2, j1, j2 in s.get_opcodes():

            ##print tag, i1, i2, j1, j2

            if tag == 'equal':

                continue

            # i1,i2 are given in offsets within basis_lines; we need to map them

            # back to offsets within the entire weave

            real_i1 = basis[i1][0]

            real_i2 = basis[i2][0]

            assert 0 <= j1

            assert j1 <= j2

            assert j2 <= len(lines)

            yield real_i1, real_i2, lines[j1:j2]