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- Committer: mbp at sourcefrog
- Date: 2005-03-09 04:51:05 UTC
- Revision ID: mbp@sourcefrog.net-20050309045105-d02cd410a115da2c
import all docs from arch
- files added:
- README
- bzrlib
- doc
- files removed:
- .bzrignore
added
removed
weave.py
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#! /usr/bin/python
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# Copyright (C) 2005 Canonical Ltd
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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# Author: Martin Pool <mbp@canonical.com>
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"""Weave - storage of related text file versions"""
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# TODO: Perhaps have copy method for Weave instances?
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# XXX: If we do weaves this way, will a merge still behave the same
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# way if it's done in a different order? That's a pretty desirable
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# property.
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# TODO: How to write these to disk? One option is cPickle, which
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# would be fast but less friendly to C, and perhaps not portable. Another is
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# TODO: Nothing here so far assumes the lines are really \n newlines,
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# rather than being split up in some other way. We could accomodate
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# binaries, perhaps by naively splitting on \n or perhaps using
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# something like a rolling checksum.
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# TODO: Perhaps track SHA-1 in the header for protection? This would
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# be redundant with it being stored in the inventory, but perhaps
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# usefully so?
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# TODO: Track version names as well as indexes.
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# TODO: Probably do transitive expansion when specifying parents?
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# TODO: Separate out some code to read and write weaves.
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# TODO: End marker for each version?
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# TODO: Check that no insertion occurs inside a deletion that was
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# active in the version of the insertion.
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try:
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set
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frozenset
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except NameError:
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from sets import Set, ImmutableSet
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set = Set
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frozenset = ImmutableSet
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del Set, ImmutableSet
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class WeaveError(Exception):
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"""Exception in processing weave"""
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class WeaveFormatError(WeaveError):
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"""Weave invariant violated"""
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class Weave(object):
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"""weave - versioned text file storage.
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A Weave manages versions of line-based text files, keeping track
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of the originating version for each line.
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To clients the "lines" of the file are represented as a list of strings.
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These strings will typically have terminal newline characters, but
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this is not required. In particular files commonly do not have a newline
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at the end of the file.
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Texts can be identified in either of two ways:
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* a nonnegative index number.
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* a version-id string.
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Typically the index number will be valid only inside this weave and
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the version-id is used to reference it in the larger world.
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The weave is represented as a list mixing edit instructions and
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literal text. Each entry in _l can be either a string (or
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unicode), or a tuple. If a string, it means that the given line
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should be output in the currently active revisions.
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If a tuple, it gives a processing instruction saying in which
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revisions the enclosed lines are active. The tuple has the form
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(instruction, version).
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The instruction can be '{' or '}' for an insertion block, and '['
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and ']' for a deletion block respectively. The version is the
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integer version index. There is no replace operator, only deletes
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and inserts.
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Constraints/notes:
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* A later version can delete lines that were introduced by any
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number of ancestor versions; this implies that deletion
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instructions can span insertion blocks without regard to the
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insertion block's nesting.
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* Similarly, deletions need not be properly nested with regard to
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each other, because they might have been generated by
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independent revisions.
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* Insertions are always made by inserting a new bracketed block
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into a single point in the previous weave. This implies they
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can nest but not overlap, and the nesting must always have later
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insertions on the inside.
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* It doesn't seem very useful to have an active insertion
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inside an inactive insertion, but it might happen.
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* Therefore, all instructions are always"considered"; that
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is passed onto and off the stack. An outer inactive block
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doesn't disable an inner block.
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* Lines are enabled if the most recent enclosing insertion is
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active and none of the enclosing deletions are active.
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* There is no point having a deletion directly inside its own
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insertion; you might as well just not write it. And there
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should be no way to get an earlier version deleting a later
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version.
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_l
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Text of the weave.
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_v
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List of versions, indexed by index number.
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For each version we store the set (included_versions), which
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lists the previous versions also considered active; the
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versions included in those versions are included transitively.
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So new versions created from nothing list []; most versions
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have a single entry; some have more.
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"""
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def __init__(self):
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self._l = []
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self._v = []
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def __eq__(self, other):
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if not isinstance(other, Weave):
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return False
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return self._v == other._v \
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and self._l == other._l
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def __ne__(self, other):
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return not self.__eq__(other)
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def add(self, parents, text):
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"""Add a single text on top of the weave.
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Returns the index number of the newly added version.
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parents
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List or set of parent version numbers. This must normally include
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the parents and the parent's parents, or wierd things might happen.
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text
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Sequence of lines to be added in the new version."""
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self._check_versions(parents)
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self._check_lines(text)
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idx = len(self._v)
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if parents:
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delta = self._delta(self.inclusions(parents), text)
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# offset gives the number of lines that have been inserted
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# into the weave up to the current point; if the original edit instruction
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# says to change line A then we actually change (A+offset)
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offset = 0
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for i1, i2, newlines in delta:
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assert 0 <= i1
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assert i1 <= i2
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assert i2 <= len(self._l)
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# the deletion and insertion are handled separately.
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# first delete the region.
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if i1 != i2:
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self._l.insert(i1+offset, ('[', idx))
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self._l.insert(i2+offset+1, (']', idx))
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offset += 2
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# is this OK???
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if newlines:
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# there may have been a deletion spanning up to
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# i2; we want to insert after this region to make sure
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# we don't destroy ourselves
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i = i2 + offset
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self._l[i:i] = [('{', idx)] \
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+ newlines \
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+ [('}', idx)]
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offset += 2 + len(newlines)
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# TODO: Could eliminate any parents that are implied by
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# the others
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self._addversion(parents)
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else:
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# special case; adding with no parents revision; can do this
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# more quickly by just appending unconditionally
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self._l.append(('{', idx))
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self._l += text
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self._l.append(('}', idx))
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self._addversion(None)
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return idx
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def inclusions(self, versions):
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"""Expand out everything included by versions."""
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i = set(versions)
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for v in versions:
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i.update(self._v[v])
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return i
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def _addversion(self, parents):
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if parents:
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self._v.append(frozenset(parents))
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else:
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self._v.append(frozenset())
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def _check_lines(self, text):
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if not isinstance(text, list):
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raise ValueError("text should be a list, not %s" % type(text))
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for l in text:
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if not isinstance(l, basestring):
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raise ValueError("text line should be a string or unicode, not %s" % type(l))
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def _check_versions(self, indexes):
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"""Check everything in the sequence of indexes is valid"""
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for i in indexes:
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try:
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self._v[i]
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except IndexError:
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raise IndexError("invalid version number %r" % i)
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def annotate(self, index):
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return list(self.annotate_iter(index))
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def annotate_iter(self, version):
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"""Yield list of (index-id, line) pairs for the specified version.
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The index indicates when the line originated in the weave."""
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included = self.inclusions([version])
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for origin, lineno, text in self._extract(included):
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yield origin, text
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def _extract(self, included):
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"""Yield annotation of lines in included set.
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Yields a sequence of tuples (origin, lineno, text), where
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origin is the origin version, lineno the index in the weave,
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and text the text of the line.
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The set typically but not necessarily corresponds to a version.
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"""
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istack = [] # versions for which an insertion block is current
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dset = set() # versions for which a deletion block is current
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isactive = False
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lineno = 0 # line of weave, 0-based
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# TODO: Probably only need to put included revisions in the istack
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# TODO: Could split this into two functions, one that updates
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# the stack and the other that processes the results -- but
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# I'm not sure it's really needed.
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WFE = WeaveFormatError
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for l in self._l:
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if isinstance(l, tuple):
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c, v = l
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if c == '{':
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if istack and (istack[-1] >= v):
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raise WFE("improperly nested insertions %d>=%d on line %d"
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% (istack[-1], v, lineno))
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istack.append(v)
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elif c == '}':
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try:
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oldv = istack.pop()
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except IndexError:
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raise WFE("unmatched close of insertion %d on line %d"
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% (v, lineno))
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if oldv != v:
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raise WFE("mismatched close of insertion %d!=%d on line %d"
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% (oldv, v, lineno))
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elif c == '[':
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# block deleted in v
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if v in dset:
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raise WFE("repeated deletion marker for version %d on line %d"
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% (v, lineno))
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if istack:
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if istack[-1] == v:
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raise WFE("version %d deletes own text on line %d"
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% (v, lineno))
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dset.add(v)
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elif c == ']':
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if v in dset:
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dset.remove(v)
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else:
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raise WFE("unmatched close of deletion %d on line %d"
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% (v, lineno))
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else:
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raise WFE("invalid processing instruction %r on line %d"
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% (l, lineno))
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else:
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assert isinstance(l, basestring)
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if not istack:
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raise WFE("literal at top level on line %d"
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% lineno)
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isactive = (istack[-1] in included) \
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and not included.intersection(dset)
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if isactive:
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origin = istack[-1]
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yield origin, lineno, l
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lineno += 1
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if istack:
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raise WFE("unclosed insertion blocks at end of weave",
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istack)
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if dset:
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raise WFE("unclosed deletion blocks at end of weave",
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dset)
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def get_iter(self, version):
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"""Yield lines for the specified version."""
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for origin, lineno, line in self._extract(self.inclusions([version])):
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yield line
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def get(self, index):
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return list(self.get_iter(index))
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def merge_iter(self, included):
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"""Return composed version of multiple included versions."""
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included = frozenset(included)
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for origin, lineno, text in self._extract(included):
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yield text
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def dump(self, to_file):
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from pprint import pprint
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print >>to_file, "Weave._l = ",
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pprint(self._l, to_file)
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print >>to_file, "Weave._v = ",
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pprint(self._v, to_file)
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def check(self):
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for vers_info in self._v:
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included = set()
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for vi in vers_info[0]:
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if vi < 0 or vi >= index:
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raise WeaveFormatError("invalid included version %d for index %d"
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% (vi, index))
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if vi in included:
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raise WeaveFormatError("repeated included version %d for index %d"
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% (vi, index))
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included.add(vi)
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def _delta(self, included, lines):
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"""Return changes from basis to new revision.
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The old text for comparison is the union of included revisions.
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This is used in inserting a new text.
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Delta is returned as a sequence of
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(weave1, weave2, newlines).
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This indicates that weave1:weave2 of the old weave should be
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replaced by the sequence of lines in newlines. Note that
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these line numbers are positions in the total weave and don't
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correspond to the lines in any extracted version, or even the
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extracted union of included versions.
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If line1=line2, this is a pure insert; if newlines=[] this is a
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pure delete. (Similar to difflib.)
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"""
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self._check_versions(included)
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##from pprint import pprint
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# first get basis for comparison
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# basis holds (lineno, origin, line)
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basis = []
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##print 'my lines:'
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##pprint(self._l)
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# basis a list of (origin, lineno, line)
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basis = list(self._extract(included))
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# now make a parallel list with only the text, to pass to the differ
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basis_lines = [line for (origin, lineno, line) in basis]
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# add a sentinal, because we can also match against the final line
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basis.append((None, len(self._l), None))
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# XXX: which line of the weave should we really consider
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# matches the end of the file? the current code says it's the
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# last line of the weave?
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from difflib import SequenceMatcher
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s = SequenceMatcher(None, basis_lines, lines)
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##print 'basis sequence:'
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##pprint(basis)
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# TODO: Perhaps return line numbers from composed weave as well?
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for tag, i1, i2, j1, j2 in s.get_opcodes():
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##print tag, i1, i2, j1, j2
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if tag == 'equal':
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continue
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# i1,i2 are given in offsets within basis_lines; we need to map them
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# back to offsets within the entire weave
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real_i1 = basis[i1][1]
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real_i2 = basis[i2][1]
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assert 0 <= j1
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assert j1 <= j2
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assert j2 <= len(lines)
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yield real_i1, real_i2, lines[j1:j2]
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def main(argv):
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import sys
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import os
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from weavefile import write_weave_v1, read_weave_v1
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cmd = argv[1]
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if cmd == 'add':
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w = read_weave_v1(file(argv[2], 'rb'))
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# at the moment, based on everything in the file
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parents = set(range(len(w._v)))
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lines = sys.stdin.readlines()
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ver = w.add(parents, lines)
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write_weave_v1(w, file(argv[2], 'wb'))
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print 'added %d' % ver
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elif cmd == 'init':
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fn = argv[2]
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if os.path.exists(fn):
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raise IOError("file exists")
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w = Weave()
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write_weave_v1(w, file(fn, 'wb'))
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elif cmd == 'get':
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w = read_weave_v1(file(argv[2], 'rb'))
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sys.stdout.writelines(w.getiter(int(argv[3])))
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elif cmd == 'annotate':
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w = read_weave_v1(file(argv[2], 'rb'))
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# newline is added to all lines regardless; too hard to get
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# reasonable formatting otherwise
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lasto = None
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for origin, text in w.annotate(int(argv[3])):
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text = text.rstrip('\r\n')
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if origin == lasto:
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print ' | %s' % (text)
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else:
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print '%5d | %s' % (origin, text)
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lasto = origin
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else:
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raise ValueError('unknown command %r' % cmd)
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if __name__ == '__main__':
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import sys
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sys.exit(main(sys.argv))
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