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# Copyright (C) 2005 Canonical Ltd
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# Author: Martin Pool <mbp@canonical.com>
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"""knit - a weave-like structure"""
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"""knit - versioned text file storage.
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A Knit manages versions of line-based text files, keeping track of the
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originating version for each line.
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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 knit and
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the version-id is used to reference it in the larger world.
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List of edit instructions.
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Each line is stored as a tuple of (index-id, text). The line
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is present in the version equal to index-id.
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List of versions, indexed by index number. Each one is an empty
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tuple because the version_id isn't stored yet.
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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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if not isinstance(text, list):
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raise ValueError("text should be a list, not %s" % type(text))
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# all of the previous texts are turned off; just append lines at the bottom
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self._l.append((idx, line))
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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, index):
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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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self._v[index] # check index is valid
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for origin, line in self._l:
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def getiter(self, index):
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"""Yield lines for the specified version."""
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for origin, line in self.annotate_iter(index):
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return list(self.getiter(index))
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def dump(self, to_file):
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from pprint import pprint
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print >>to_file, "knit lines:"
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pprint(self._l, to_file)
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def update_knit(knit, new_vers, new_lines):
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"""Return a new knit whose text matches new_lines.
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First of all the knit is diffed against the new lines, considering
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only the text of the lines from the knit. This identifies lines
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unchanged from the knit, plus insertions and deletions.
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The deletions are marked as deleted. The insertions are added
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with their new values.
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if not isinstance(new_vers, int):
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raise TypeError('new version-id must be an int: %r' % new_vers)
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from difflib import SequenceMatcher
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knit_lines = knit2text(knit)
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m = SequenceMatcher(None, knit_lines, new_lines)
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for block in m.get_matching_blocks():
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print "a[%d] and b[%d] match for %d elements" % block
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for tag, i1, i2, j1, j2 in m.get_opcodes():
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print ("%7s a[%d:%d] (%s) b[%d:%d] (%s)" %
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(tag, i1, i2, knit_lines[i1:i2], j1, j2, new_lines[j1:j2]))
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new_knit.extend(knit[i1:i2])
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elif tag == 'delete':
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for i in range(i1, i2):
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new_knit.append((kl[0], kl[1], False))
added
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knit.py
