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from difflib import SequenceMatcher
from bzrlib import patiencediff
class MultiParent(object):
def __init__(self, hunks=None):
if hunks is not None:
self.hunks = hunks
else:
self.hunks = []
def __repr__(self):
return "MultiParent(%r)" % self.hunks
def __eq__(self, other):
if self.__class__ is not other.__class__:
return False
return (self.hunks == other.hunks)
@staticmethod
def from_lines(text, parents=()):
"""Produce a MultiParent from a list of lines and parents"""
def compare(parent):
matcher = patiencediff.PatienceSequenceMatcher(None, parent,
text)
return matcher.get_matching_blocks()
parent_comparisons = [compare(p) for p in parents]
cur_line = 0
new_text = NewText([])
parent_text = []
block_iter = [iter(i) for i in parent_comparisons]
diff = MultiParent([])
def next_block(p):
try:
return block_iter[p].next()
except StopIteration:
return None
cur_block = [next_block(p) for p, i in enumerate(block_iter)]
while cur_line < len(text):
best_match = None
for p, block in enumerate(cur_block):
if block is None:
continue
i, j, n = block
while j + n < cur_line:
block = cur_block[p] = next_block(p)
if block is None:
break
i, j, n = block
if block is None:
continue
if j > cur_line:
continue
offset = cur_line - j
i += offset
j = cur_line
n -= offset
if n == 0:
continue
if best_match is None or n > best_match.num_lines:
best_match = ParentText(p, i, j, n)
if best_match is None:
new_text.lines.append(text[cur_line])
cur_line += 1
else:
if len(new_text.lines) > 0:
diff.hunks.append(new_text)
new_text = NewText([])
diff.hunks.append(best_match)
cur_line += best_match.num_lines
if len(new_text.lines) > 0:
diff.hunks.append(new_text)
return diff
@classmethod
def from_texts(cls, text, parents=()):
"""Produce a MultiParent from a text and list of parent text"""
return cls.from_lines(text.splitlines(True),
[p.splitlines(True) for p in parents])
def to_patch(self):
"""Yield text lines for a patch"""
for hunk in self.hunks:
for line in hunk.to_patch():
yield line
def range_iterator(self):
"""Iterate through the hunks, with range indicated
kind is "new" or "parent".
for "new", data is a list of lines.
for "parent", data is (parent, parent_start, parent_end)
:return: a generator of (start, end, kind, data)
"""
start = 0
for hunk in self.hunks:
if isinstance(hunk, NewText):
kind = 'new'
end = start + len(hunk.lines)
data = hunk.lines
else:
kind = 'parent'
start = hunk.child_pos
end = start + hunk.num_lines
data = (hunk.parent, hunk.parent_pos, hunk.parent_pos +
hunk.num_lines)
yield start, end, kind, data
start = end
def num_lines(self):
extra_n = 0
for hunk in reversed(self.hunks):
if isinstance(hunk, ParentText):
return hunk.child_pos + hunk.num_lines + extra_n
extra_n += len(hunk.lines)
return extra_n
class NewText(object):
"""The contents of text that is introduced by this text"""
def __init__(self, lines):
self.lines = lines
def __eq__(self, other):
if self.__class__ is not other.__class__:
return False
return (other.lines == self.lines)
def __repr__(self):
return 'NewText(%r)' % self.lines
def to_patch(self):
yield 'i %d\n' % len(self.lines)
for line in self.lines:
yield line
yield '\n'
class ParentText(object):
"""A reference to text present in a parent text"""
def __init__(self, parent, parent_pos, child_pos, num_lines):
self.parent = parent
self.parent_pos = parent_pos
self.child_pos = child_pos
self.num_lines = num_lines
def __repr__(self):
return 'ParentText(%(parent)r, %(parent_pos)r, %(child_pos)r,'\
' %(num_lines)r)' % self.__dict__
def __eq__(self, other):
if self.__class__ != other.__class__:
return False
return (self.__dict__ == other.__dict__)
def to_patch(self):
yield 'c %(parent)d %(parent_pos)d %(child_pos)d %(num_lines)d\n'\
% self.__dict__
class MultiVersionedFile(object):
"""VersionedFile skeleton for MultiParent"""
def __init__(self, snapshot_interval=25, max_snapshots=None):
self._diffs = {}
self._lines = {}
self._parents = {}
self._snapshots = set()
self.snapshot_interval = snapshot_interval
self.max_snapshots = max_snapshots
def do_snapshot(self, version_id, parent_ids):
if self.snapshot_interval is None:
return False
if self.max_snapshots is not None and\
len(self._snapshots) == self.max_snapshots:
return False
if len(parent_ids) == 0:
return True
for ignored in xrange(self.snapshot_interval):
if len(parent_ids) == 0:
return False
version_ids = parent_ids
parent_ids = []
for version_id in version_ids:
if version_id not in self._snapshots:
parent_ids.extend(self._parents[version_id])
else:
return True
def add_version(self, lines, version_id, parent_ids,
force_snapshot=None):
if force_snapshot is None:
do_snapshot = self.do_snapshot(version_id, parent_ids)
else:
do_snapshot = force_snapshot
if do_snapshot:
self._snapshots.add(version_id)
diff = MultiParent([NewText(lines)])
else:
parent_lines = self.get_line_list(parent_ids)
diff = MultiParent.from_lines(lines, parent_lines)
self.add_diff(diff, version_id, parent_ids)
self._lines[version_id] = lines
def add_diff(self, diff, version_id, parent_ids):
self._diffs[version_id] = diff
self._parents[version_id] = parent_ids
def clear_cache(self):
self._lines.clear()
def get_line_list(self, version_ids):
return [self.cache_version(v) for v in version_ids]
def cache_version(self, version_id):
try:
return self._lines[version_id]
except KeyError:
pass
diff = self._diffs[version_id]
lines = []
reconstructor = _Reconstructor(self._diffs, self._lines,
self._parents)
reconstructor.reconstruct_version(lines, version_id)
self._lines[version_id] = lines
return lines
class _Reconstructor(object):
"""Build a text from the diffs, ancestry graph and cached lines"""
def __init__(self, diffs, lines, parents):
self.diffs = diffs
self.lines = lines
self.parents = parents
self.cursor = {}
def reconstruct(self, lines, parent_text, version_id):
"""Append the lines referred to by a ParentText to lines"""
parent_id = self.parents[version_id][parent_text.parent]
end = parent_text.parent_pos + parent_text.num_lines
return self._reconstruct(lines, parent_id, parent_text.parent_pos,
end)
def _reconstruct(self, lines, req_version_id, req_start, req_end):
"""Append lines for the requested version_id range"""
# stack of pending range requests
pending_reqs = [(req_version_id, req_start, req_end)]
while len(pending_reqs) > 0:
req_version_id, req_start, req_end = pending_reqs.pop()
# lazily allocate cursors for versions
try:
start, end, kind, data, iterator = self.cursor[req_version_id]
except KeyError:
iterator = self.diffs[req_version_id].range_iterator()
start, end, kind, data = iterator.next()
# find the first hunk relevant to the request
while end <= req_start:
start, end, kind, data = iterator.next()
self.cursor[req_version_id] = start, end, kind, data, iterator
# if the hunk can't satisfy the whole request, split it in two,
# and leave the second half for later.
if req_end > end:
pending_reqs.append((req_version_id, end, req_end))
req_end = end
if kind == 'new':
lines.extend(data[req_start - start: (req_end - start)])
else:
# If the hunk is a ParentText, rewrite it as a range request
# for the parent, and make it the next pending request.
parent, parent_start, parent_end = data
new_version_id = self.parents[req_version_id][parent]
new_start = parent_start + req_start - start
new_end = parent_end + req_end - end
pending_reqs.append((new_version_id, new_start, new_end))
def reconstruct_version(self, lines, version_id):
length = self.diffs[version_id].num_lines()
return self._reconstruct(lines, version_id, 0, length)
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