merge: prevent simplemerge from mutating label list

simplemerge was using list.pop() to remove items from the labels list. This
mutated the list and made it unusable by other calls (for instance, it might be
used in both the premerge and actual merge stages).

mercurial/simplemerge.py

@@ -1,453 +1,453 b''
 # Copyright (C) 2004, 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, see <http://www.gnu.org/licenses/>.
 
 # mbp: "you know that thing where cvs gives you conflict markers?"
 # s: "i hate that."
 
 from i18n import _
 import scmutil, util, mdiff
 import sys, os
 
 class CantReprocessAndShowBase(Exception):
     pass
 
 def intersect(ra, rb):
     """Given two ranges return the range where they intersect or None.
 
     >>> intersect((0, 10), (0, 6))
     (0, 6)
     >>> intersect((0, 10), (5, 15))
     (5, 10)
     >>> intersect((0, 10), (10, 15))
     >>> intersect((0, 9), (10, 15))
     >>> intersect((0, 9), (7, 15))
     (7, 9)
     """
     assert ra[0] <= ra[1]
     assert rb[0] <= rb[1]
 
     sa = max(ra[0], rb[0])
     sb = min(ra[1], rb[1])
     if sa < sb:
         return sa, sb
     else:
         return None
 
 def compare_range(a, astart, aend, b, bstart, bend):
     """Compare a[astart:aend] == b[bstart:bend], without slicing.
     """
     if (aend - astart) != (bend - bstart):
         return False
     for ia, ib in zip(xrange(astart, aend), xrange(bstart, bend)):
         if a[ia] != b[ib]:
             return False
     else:
         return True
 
 class Merge3Text(object):
     """3-way merge of texts.
 
     Given strings BASE, OTHER, THIS, tries to produce a combined text
     incorporating the changes from both BASE->OTHER and BASE->THIS."""
     def __init__(self, basetext, atext, btext, base=None, a=None, b=None):
         self.basetext = basetext
         self.atext = atext
         self.btext = btext
         if base is None:
             base = mdiff.splitnewlines(basetext)
         if a is None:
             a = mdiff.splitnewlines(atext)
         if b is None:
             b = mdiff.splitnewlines(btext)
         self.base = base
         self.a = a
         self.b = b
 
     def merge_lines(self,
                     name_a=None,
                     name_b=None,
                     name_base=None,
                     start_marker='<<<<<<<',
                     mid_marker='=======',
                     end_marker='>>>>>>>',
                     base_marker=None,
                     reprocess=False):
         """Return merge in cvs-like form.
         """
         self.conflicts = False
         newline = '\n'
         if len(self.a) > 0:
             if self.a[0].endswith('\r\n'):
                 newline = '\r\n'
             elif self.a[0].endswith('\r'):
                 newline = '\r'
         if base_marker and reprocess:
             raise CantReprocessAndShowBase
         if name_a:
             start_marker = start_marker + ' ' + name_a
         if name_b:
             end_marker = end_marker + ' ' + name_b
         if name_base and base_marker:
             base_marker = base_marker + ' ' + name_base
         merge_regions = self.merge_regions()
         if reprocess is True:
             merge_regions = self.reprocess_merge_regions(merge_regions)
         for t in merge_regions:
             what = t[0]
             if what == 'unchanged':
                 for i in range(t[1], t[2]):
                     yield self.base[i]
             elif what == 'a' or what == 'same':
                 for i in range(t[1], t[2]):
                     yield self.a[i]
             elif what == 'b':
                 for i in range(t[1], t[2]):
                     yield self.b[i]
             elif what == 'conflict':
                 self.conflicts = True
                 yield start_marker + newline
                 for i in range(t[3], t[4]):
                     yield self.a[i]
                 if base_marker is not None:
                     yield base_marker + newline
                     for i in range(t[1], t[2]):
                         yield self.base[i]
                 yield mid_marker + newline
                 for i in range(t[5], t[6]):
                     yield self.b[i]
                 yield end_marker + newline
             else:
                 raise ValueError(what)
 
     def merge_annotated(self):
         """Return merge with conflicts, showing origin of lines.
 
         Most useful for debugging merge.
         """
         for t in self.merge_regions():
             what = t[0]
             if what == 'unchanged':
                 for i in range(t[1], t[2]):
                     yield 'u | ' + self.base[i]
             elif what == 'a' or what == 'same':
                 for i in range(t[1], t[2]):
                     yield what[0] + ' | ' + self.a[i]
             elif what == 'b':
                 for i in range(t[1], t[2]):
                     yield 'b | ' + self.b[i]
             elif what == 'conflict':
                 yield '<<<<\n'
                 for i in range(t[3], t[4]):
                     yield 'A | ' + self.a[i]
                 yield '----\n'
                 for i in range(t[5], t[6]):
                     yield 'B | ' + self.b[i]
                 yield '>>>>\n'
             else:
                 raise ValueError(what)
 
     def merge_groups(self):
         """Yield sequence of line groups.  Each one is a tuple:
 
         'unchanged', lines
              Lines unchanged from base
 
         'a', lines
              Lines taken from a
 
         'same', lines
              Lines taken from a (and equal to b)
 
         'b', lines
              Lines taken from b
 
         'conflict', base_lines, a_lines, b_lines
              Lines from base were changed to either a or b and conflict.
         """
         for t in self.merge_regions():
             what = t[0]
             if what == 'unchanged':
                 yield what, self.base[t[1]:t[2]]
             elif what == 'a' or what == 'same':
                 yield what, self.a[t[1]:t[2]]
             elif what == 'b':
                 yield what, self.b[t[1]:t[2]]
             elif what == 'conflict':
                 yield (what,
                        self.base[t[1]:t[2]],
                        self.a[t[3]:t[4]],
                        self.b[t[5]:t[6]])
             else:
                 raise ValueError(what)
 
     def merge_regions(self):
         """Return sequences of matching and conflicting regions.
 
         This returns tuples, where the first value says what kind we
         have:
 
         'unchanged', start, end
              Take a region of base[start:end]
 
         'same', astart, aend
              b and a are different from base but give the same result
 
         'a', start, end
              Non-clashing insertion from a[start:end]
 
         Method is as follows:
 
         The two sequences align only on regions which match the base
         and both descendants.  These are found by doing a two-way diff
         of each one against the base, and then finding the
         intersections between those regions.  These "sync regions"
         are by definition unchanged in both and easily dealt with.
 
         The regions in between can be in any of three cases:
         conflicted, or changed on only one side.
         """
 
         # section a[0:ia] has been disposed of, etc
         iz = ia = ib = 0
 
         for region in self.find_sync_regions():
             zmatch, zend, amatch, aend, bmatch, bend = region
             #print 'match base [%d:%d]' % (zmatch, zend)
 
             matchlen = zend - zmatch
             assert matchlen >= 0
             assert matchlen == (aend - amatch)
             assert matchlen == (bend - bmatch)
 
             len_a = amatch - ia
             len_b = bmatch - ib
             len_base = zmatch - iz
             assert len_a >= 0
             assert len_b >= 0
             assert len_base >= 0
 
             #print 'unmatched a=%d, b=%d' % (len_a, len_b)
 
             if len_a or len_b:
                 # try to avoid actually slicing the lists
                 equal_a = compare_range(self.a, ia, amatch,
                                         self.base, iz, zmatch)
                 equal_b = compare_range(self.b, ib, bmatch,
                                         self.base, iz, zmatch)
                 same = compare_range(self.a, ia, amatch,
                                      self.b, ib, bmatch)
 
                 if same:
                     yield 'same', ia, amatch
                 elif equal_a and not equal_b:
                     yield 'b', ib, bmatch
                 elif equal_b and not equal_a:
                     yield 'a', ia, amatch
                 elif not equal_a and not equal_b:
                     yield 'conflict', iz, zmatch, ia, amatch, ib, bmatch
                 else:
                     raise AssertionError("can't handle a=b=base but unmatched")
 
                 ia = amatch
                 ib = bmatch
             iz = zmatch
 
             # if the same part of the base was deleted on both sides
             # that's OK, we can just skip it.
 
 
             if matchlen > 0:
                 assert ia == amatch
                 assert ib == bmatch
                 assert iz == zmatch
 
                 yield 'unchanged', zmatch, zend
                 iz = zend
                 ia = aend
                 ib = bend
 
     def reprocess_merge_regions(self, merge_regions):
         """Where there are conflict regions, remove the agreed lines.
 
         Lines where both A and B have made the same changes are
         eliminated.
         """
         for region in merge_regions:
             if region[0] != "conflict":
                 yield region
                 continue
             type, iz, zmatch, ia, amatch, ib, bmatch = region
             a_region = self.a[ia:amatch]
             b_region = self.b[ib:bmatch]
             matches = mdiff.get_matching_blocks(''.join(a_region),
                                                 ''.join(b_region))
             next_a = ia
             next_b = ib
             for region_ia, region_ib, region_len in matches[:-1]:
                 region_ia += ia
                 region_ib += ib
                 reg = self.mismatch_region(next_a, region_ia, next_b,
                                            region_ib)
                 if reg is not None:
                     yield reg
                 yield 'same', region_ia, region_len + region_ia
                 next_a = region_ia + region_len
                 next_b = region_ib + region_len
             reg = self.mismatch_region(next_a, amatch, next_b, bmatch)
             if reg is not None:
                 yield reg
 
     def mismatch_region(next_a, region_ia,  next_b, region_ib):
         if next_a < region_ia or next_b < region_ib:
             return 'conflict', None, None, next_a, region_ia, next_b, region_ib
     mismatch_region = staticmethod(mismatch_region)
 
     def find_sync_regions(self):
         """Return a list of sync regions, where both descendants match the base.
 
         Generates a list of (base1, base2, a1, a2, b1, b2).  There is
         always a zero-length sync region at the end of all the files.
         """
 
         ia = ib = 0
         amatches = mdiff.get_matching_blocks(self.basetext, self.atext)
         bmatches = mdiff.get_matching_blocks(self.basetext, self.btext)
         len_a = len(amatches)
         len_b = len(bmatches)
 
         sl = []
 
         while ia < len_a and ib < len_b:
             abase, amatch, alen = amatches[ia]
             bbase, bmatch, blen = bmatches[ib]
 
             # there is an unconflicted block at i; how long does it
             # extend?  until whichever one ends earlier.
             i = intersect((abase, abase + alen), (bbase, bbase + blen))
             if i:
                 intbase = i[0]
                 intend = i[1]
                 intlen = intend - intbase
 
                 # found a match of base[i[0], i[1]]; this may be less than
                 # the region that matches in either one
                 assert intlen <= alen
                 assert intlen <= blen
                 assert abase <= intbase
                 assert bbase <= intbase
 
                 asub = amatch + (intbase - abase)
                 bsub = bmatch + (intbase - bbase)
                 aend = asub + intlen
                 bend = bsub + intlen
 
                 assert self.base[intbase:intend] == self.a[asub:aend], \
                        (self.base[intbase:intend], self.a[asub:aend])
 
                 assert self.base[intbase:intend] == self.b[bsub:bend]
 
                 sl.append((intbase, intend,
                            asub, aend,
                            bsub, bend))
 
             # advance whichever one ends first in the base text
             if (abase + alen) < (bbase + blen):
                 ia += 1
             else:
                 ib += 1
 
         intbase = len(self.base)
         abase = len(self.a)
         bbase = len(self.b)
         sl.append((intbase, intbase, abase, abase, bbase, bbase))
 
         return sl
 
     def find_unconflicted(self):
         """Return a list of ranges in base that are not conflicted."""
         am = mdiff.get_matching_blocks(self.basetext, self.atext)
         bm = mdiff.get_matching_blocks(self.basetext, self.btext)
 
         unc = []
 
         while am and bm:
             # there is an unconflicted block at i; how long does it
             # extend?  until whichever one ends earlier.
             a1 = am[0][0]
             a2 = a1 + am[0][2]
             b1 = bm[0][0]
             b2 = b1 + bm[0][2]
             i = intersect((a1, a2), (b1, b2))
             if i:
                 unc.append(i)
 
             if a2 < b2:
                 del am[0]
             else:
                 del bm[0]
 
         return unc
 
 def simplemerge(ui, local, base, other, **opts):
     def readfile(filename):
         f = open(filename, "rb")
         text = f.read()
         f.close()
         if util.binary(text):
             msg = _("%s looks like a binary file.") % filename
             if not opts.get('quiet'):
                 ui.warn(_('warning: %s\n') % msg)
             if not opts.get('text'):
                 raise util.Abort(msg)
         return text
 
     name_a = local
     name_b = other
     labels = opts.get('label', [])
-    if labels:
-        name_a = labels.pop(0)
-    if labels:
-        name_b = labels.pop(0)
-    if labels:
+    if len(labels) > 0:
+        name_a = labels[0]
+    if len(labels) > 1:
+        name_b = labels[1]
+    if len(labels) > 2:
         raise util.Abort(_("can only specify two labels."))
 
     try:
         localtext = readfile(local)
         basetext = readfile(base)
         othertext = readfile(other)
     except util.Abort:
         return 1
 
     local = os.path.realpath(local)
     if not opts.get('print'):
         opener = scmutil.opener(os.path.dirname(local))
         out = opener(os.path.basename(local), "w", atomictemp=True)
     else:
         out = sys.stdout
 
     reprocess = not opts.get('no_minimal')
 
     m3 = Merge3Text(basetext, localtext, othertext)
     for line in m3.merge_lines(name_a=name_a, name_b=name_b,
                                reprocess=reprocess):
         out.write(line)
 
     if not opts.get('print'):
         out.close()
 
     if m3.conflicts:
         if not opts.get('quiet'):
             ui.warn(_("warning: conflicts during merge.\n"))
         return 1