3
# Copyright (C) 2005 Canonical Ltd
5
# This program is free software; you can redistribute it and/or modify
6
# it under the terms of the GNU General Public License as published by
7
# the Free Software Foundation; either version 2 of the License, or
8
# (at your option) any later version.
10
# This program is distributed in the hope that it will be useful,
11
# but WITHOUT ANY WARRANTY; without even the implied warranty of
12
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13
# GNU General Public License for more details.
15
# You should have received a copy of the GNU General Public License
16
# along with this program; if not, write to the Free Software
17
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19
# Author: Martin Pool <mbp@canonical.com>
22
"""Weave - storage of related text file versions"""
24
# TODO: Perhaps have copy method for Weave instances?
26
# XXX: If we do weaves this way, will a merge still behave the same
27
# way if it's done in a different order? That's a pretty desirable
30
# TODO: How to write these to disk? One option is cPickle, which
31
# would be fast but less friendly to C, and perhaps not portable. Another is
33
# TODO: Nothing here so far assumes the lines are really \n newlines,
34
# rather than being split up in some other way. We could accomodate
35
# binaries, perhaps by naively splitting on \n or perhaps using
36
# something like a rolling checksum.
38
# TODO: Perhaps track SHA-1 in the header for protection? This would
39
# be redundant with it being stored in the inventory, but perhaps
42
# TODO: Track version names as well as indexes.
44
# TODO: Probably do transitive expansion when specifying parents?
46
# TODO: Separate out some code to read and write weaves.
48
# TODO: End marker for each version so we can stop reading?
50
# TODO: Check that no insertion occurs inside a deletion that was
51
# active in the version of the insertion.
53
# TODO: Perhaps a special slower check() method that verifies more
54
# nesting constraints and the MD5 of each version?
62
from sets import Set, ImmutableSet
64
frozenset = ImmutableSet
68
class WeaveError(Exception):
69
"""Exception in processing weave"""
72
class WeaveFormatError(WeaveError):
73
"""Weave invariant violated"""
77
"""weave - versioned text file storage.
79
A Weave manages versions of line-based text files, keeping track
80
of the originating version for each line.
82
To clients the "lines" of the file are represented as a list of strings.
83
These strings will typically have terminal newline characters, but
84
this is not required. In particular files commonly do not have a newline
85
at the end of the file.
87
Texts can be identified in either of two ways:
89
* a nonnegative index number.
91
* a version-id string.
93
Typically the index number will be valid only inside this weave and
94
the version-id is used to reference it in the larger world.
96
The weave is represented as a list mixing edit instructions and
97
literal text. Each entry in _l can be either a string (or
98
unicode), or a tuple. If a string, it means that the given line
99
should be output in the currently active revisions.
101
If a tuple, it gives a processing instruction saying in which
102
revisions the enclosed lines are active. The tuple has the form
103
(instruction, version).
105
The instruction can be '{' or '}' for an insertion block, and '['
106
and ']' for a deletion block respectively. The version is the
107
integer version index. There is no replace operator, only deletes
112
* A later version can delete lines that were introduced by any
113
number of ancestor versions; this implies that deletion
114
instructions can span insertion blocks without regard to the
115
insertion block's nesting.
117
* Similarly, deletions need not be properly nested with regard to
118
each other, because they might have been generated by
119
independent revisions.
121
* Insertions are always made by inserting a new bracketed block
122
into a single point in the previous weave. This implies they
123
can nest but not overlap, and the nesting must always have later
124
insertions on the inside.
126
* It doesn't seem very useful to have an active insertion
127
inside an inactive insertion, but it might happen.
129
* Therefore, all instructions are always"considered"; that
130
is passed onto and off the stack. An outer inactive block
131
doesn't disable an inner block.
133
* Lines are enabled if the most recent enclosing insertion is
134
active and none of the enclosing deletions are active.
136
* There is no point having a deletion directly inside its own
137
insertion; you might as well just not write it. And there
138
should be no way to get an earlier version deleting a later
145
List of parents, indexed by version number.
146
It is only necessary to store the minimal set of parents for
147
each version; the parent's parents are implied.
150
List of hex SHA-1 of each version, or None if not recorded.
158
def __eq__(self, other):
159
if not isinstance(other, Weave):
161
return self._v == other._v \
162
and self._l == other._l
165
def __ne__(self, other):
166
return not self.__eq__(other)
169
def add(self, parents, text):
170
"""Add a single text on top of the weave.
172
Returns the index number of the newly added version.
175
List or set of direct parent version numbers.
178
Sequence of lines to be added in the new version."""
179
## self._check_versions(parents)
180
## self._check_lines(text)
191
ancestors = self.inclusions(parents)
192
delta = self._delta(ancestors, text)
194
# offset gives the number of lines that have been inserted
195
# into the weave up to the current point; if the original edit instruction
196
# says to change line A then we actually change (A+offset)
199
for i1, i2, newlines in delta:
202
assert i2 <= len(self._l)
204
# the deletion and insertion are handled separately.
205
# first delete the region.
207
self._l.insert(i1+offset, ('[', idx))
208
self._l.insert(i2+offset+1, (']', idx))
213
# there may have been a deletion spanning up to
214
# i2; we want to insert after this region to make sure
215
# we don't destroy ourselves
217
self._l[i:i] = [('{', idx)] \
220
offset += 2 + len(newlines)
222
self._addversion(parents)
224
# special case; adding with no parents revision; can do this
225
# more quickly by just appending unconditionally
226
self._l.append(('{', idx))
228
self._l.append(('}', idx))
230
self._addversion(None)
232
self._sha1s.append(sha1)
237
def inclusions(self, versions):
238
"""Return set of all ancestors of given version(s)."""
244
# include all its parents
249
raise ValueError("version %d not present in weave" % v)
252
def minimal_parents(self, version):
253
"""Find the minimal set of parents for the version."""
254
included = self._v[version]
259
li.sort(reverse=True)
267
gotit.update(self.inclusions(pv))
269
assert mininc[0] >= 0
270
assert mininc[-1] < version
274
def _addversion(self, parents):
276
self._v.append(parents)
278
self._v.append(frozenset())
281
def _check_lines(self, text):
282
if not isinstance(text, list):
283
raise ValueError("text should be a list, not %s" % type(text))
286
if not isinstance(l, basestring):
287
raise ValueError("text line should be a string or unicode, not %s"
292
def _check_versions(self, indexes):
293
"""Check everything in the sequence of indexes is valid"""
298
raise IndexError("invalid version number %r" % i)
301
def annotate(self, index):
302
return list(self.annotate_iter(index))
305
def annotate_iter(self, version):
306
"""Yield list of (index-id, line) pairs for the specified version.
308
The index indicates when the line originated in the weave."""
309
for origin, lineno, text in self._extract([version]):
313
def _extract(self, versions):
314
"""Yield annotation of lines in included set.
316
Yields a sequence of tuples (origin, lineno, text), where
317
origin is the origin version, lineno the index in the weave,
318
and text the text of the line.
320
The set typically but not necessarily corresponds to a version.
322
included = self.inclusions(versions)
327
lineno = 0 # line of weave, 0-based
331
WFE = WeaveFormatError
334
if isinstance(l, tuple):
337
assert v not in istack
340
isactive = (v in included)
344
isactive = (not dset) and (istack and istack[-1] in included)
355
isactive = (not dset) and (istack and istack[-1] in included)
357
assert isinstance(l, basestring)
359
yield istack[-1], lineno, l
363
raise WFE("unclosed insertion blocks at end of weave",
366
raise WFE("unclosed deletion blocks at end of weave",
370
def get_iter(self, version):
371
"""Yield lines for the specified version."""
372
for origin, lineno, line in self._extract([version]):
376
def get(self, index):
377
return list(self.get_iter(index))
380
def mash_iter(self, included):
381
"""Return composed version of multiple included versions."""
382
included = frozenset(included)
383
for origin, lineno, text in self._extract(included):
387
def dump(self, to_file):
388
from pprint import pprint
389
print >>to_file, "Weave._l = ",
390
pprint(self._l, to_file)
391
print >>to_file, "Weave._v = ",
392
pprint(self._v, to_file)
396
def numversions(self):
398
assert l == len(self._sha1s)
403
# check no circular inclusions
404
for version in range(self.numversions()):
405
inclusions = list(self._v[version])
408
if inclusions[-1] >= version:
409
raise WeaveFormatError("invalid included version %d for index %d"
410
% (inclusions[-1], version))
412
# try extracting all versions; this is a bit slow and parallel
413
# extraction could be used
415
for version in range(self.numversions()):
417
for l in self.get_iter(version):
420
expected = self._sha1s[version]
422
raise WeaveError("mismatched sha1 for version %d; "
423
"got %s, expected %s"
424
% (version, hd, expected))
426
# TODO: check insertions are properly nested, that there are
427
# no lines outside of insertion blocks, that deletions are
428
# properly paired, etc.
432
def merge(self, merge_versions):
433
"""Automerge and mark conflicts between versions.
435
This returns a sequence, each entry describing alternatives
436
for a chunk of the file. Each of the alternatives is given as
439
If there is a chunk of the file where there's no diagreement,
440
only one alternative is given.
443
# approach: find the included versions common to all the
445
raise NotImplementedError()
449
def _delta(self, included, lines):
450
"""Return changes from basis to new revision.
452
The old text for comparison is the union of included revisions.
454
This is used in inserting a new text.
456
Delta is returned as a sequence of
457
(weave1, weave2, newlines).
459
This indicates that weave1:weave2 of the old weave should be
460
replaced by the sequence of lines in newlines. Note that
461
these line numbers are positions in the total weave and don't
462
correspond to the lines in any extracted version, or even the
463
extracted union of included versions.
465
If line1=line2, this is a pure insert; if newlines=[] this is a
466
pure delete. (Similar to difflib.)
468
# basis a list of (origin, lineno, line)
471
for origin, lineno, line in self._extract(included):
472
basis_lineno.append(lineno)
473
basis_lines.append(line)
475
# add a sentinal, because we can also match against the final line
476
basis_lineno.append(len(self._l))
478
# XXX: which line of the weave should we really consider
479
# matches the end of the file? the current code says it's the
480
# last line of the weave?
482
from difflib import SequenceMatcher
483
s = SequenceMatcher(None, basis_lines, lines)
485
# TODO: Perhaps return line numbers from composed weave as well?
487
for tag, i1, i2, j1, j2 in s.get_opcodes():
488
##print tag, i1, i2, j1, j2
493
# i1,i2 are given in offsets within basis_lines; we need to map them
494
# back to offsets within the entire weave
495
real_i1 = basis_lineno[i1]
496
real_i2 = basis_lineno[i2]
500
assert j2 <= len(lines)
502
yield real_i1, real_i2, lines[j1:j2]
506
def weave_info(filename, out):
507
"""Show some text information about the weave."""
508
from weavefile import read_weave
509
wf = file(filename, 'rb')
511
# FIXME: doesn't work on pipes
512
weave_size = wf.tell()
513
print >>out, "weave file size %d bytes" % weave_size
514
print >>out, "weave contains %d versions" % len(w._v)
517
print '%6s %6s %8s %40s %20s' % ('ver', 'lines', 'bytes', 'sha1', 'parents')
518
for i in (6, 6, 8, 40, 20):
521
for i in range(len(w._v)):
524
bytes = sum((len(a) for a in text))
526
print '%6d %6d %8d %40s' % (i, lines, bytes, sha1),
532
print >>out, "versions total %d bytes" % total
533
print >>out, "compression ratio %.3f" % (float(total)/float(weave_size))
537
print """bzr weave tool
539
Experimental tool for weave algorithm.
543
Create an empty weave file
544
weave get WEAVEFILE VERSION
545
Write out specified version.
546
weave check WEAVEFILE
547
Check consistency of all versions.
549
Display table of contents.
550
weave add WEAVEFILE [BASE...] < NEWTEXT
551
Add NEWTEXT, with specified parent versions.
552
weave annotate WEAVEFILE VERSION
553
Display origin of each line.
554
weave mash WEAVEFILE VERSION...
555
Display composite of all selected versions.
556
weave merge WEAVEFILE VERSION1 VERSION2 > OUT
557
Auto-merge two versions and display conflicts.
561
% weave init foo.weave
563
% weave add foo.weave < foo.txt
566
(create updated version)
568
% weave get foo.weave 0 | diff -u - foo.txt
569
% weave add foo.weave 0 < foo.txt
572
% weave get foo.weave 0 > foo.txt (create forked version)
574
% weave add foo.weave 0 < foo.txt
577
% weave merge foo.weave 1 2 > foo.txt (merge them)
578
% vi foo.txt (resolve conflicts)
579
% weave add foo.weave 1 2 < foo.txt (commit merged version)
588
from weavefile import write_weave, read_weave
592
return read_weave(file(argv[2], 'rb'))
598
# at the moment, based on everything in the file
599
parents = map(int, argv[3:])
600
lines = sys.stdin.readlines()
601
ver = w.add(parents, lines)
602
write_weave(w, file(argv[2], 'wb'))
603
print 'added version %d' % ver
606
if os.path.exists(fn):
607
raise IOError("file exists")
609
write_weave(w, file(fn, 'wb'))
610
elif cmd == 'get': # get one version
612
sys.stdout.writelines(w.get_iter(int(argv[3])))
614
elif cmd == 'mash': # get composite
616
sys.stdout.writelines(w.mash_iter(map(int, argv[3:])))
618
elif cmd == 'annotate':
620
# newline is added to all lines regardless; too hard to get
621
# reasonable formatting otherwise
623
for origin, text in w.annotate(int(argv[3])):
624
text = text.rstrip('\r\n')
626
print ' | %s' % (text)
628
print '%5d | %s' % (origin, text)
632
weave_info(argv[2], sys.stdout)
638
elif cmd == 'inclusions':
640
print ' '.join(map(str, w.inclusions([int(argv[3])])))
642
elif cmd == 'parents':
644
print ' '.join(map(str, w._v[int(argv[3])]))
652
v1, v2 = map(int, argv[3:5])
654
basis = w.inclusions([v1]).intersection(w.inclusions([v2]))
656
base_lines = list(w.mash_iter(basis))
657
a_lines = list(w.get(v1))
658
b_lines = list(w.get(v2))
660
from bzrlib.merge3 import Merge3
661
m3 = Merge3(base_lines, a_lines, b_lines)
663
name_a = 'version %d' % v1
664
name_b = 'version %d' % v2
665
sys.stdout.writelines(m3.merge_lines(name_a=name_a, name_b=name_b))
667
raise ValueError('unknown command %r' % cmd)
670
if __name__ == '__main__':
672
sys.exit(main(sys.argv))
added
removed
bzrlib/weave.py
