MCL/sf/adapt/qemu: comparison symbian-qemu-0.9.1-12/python-win32-2.6.1/lib/difflib.py

equal deleted inserted replaced

-:ffa851df0825
+:2fb8b9db1c86
+#! /usr/bin/env python
+"""
+Module difflib -- helpers for computing deltas between objects.
+Function get_close_matches(word, possibilities, n=3, cutoff=0.6):
+Use SequenceMatcher to return list of the best "good enough" matches.
+Function context_diff(a, b):
+For two lists of strings, return a delta in context diff format.
+Function ndiff(a, b):
+Return a delta: the difference between `a` and `b` (lists of strings).
+Function restore(delta, which):
+Return one of the two sequences that generated an ndiff delta.
+Function unified_diff(a, b):
+For two lists of strings, return a delta in unified diff format.
+Class SequenceMatcher:
+A flexible class for comparing pairs of sequences of any type.
+Class Differ:
+For producing human-readable deltas from sequences of lines of text.
+Class HtmlDiff:
+For producing HTML side by side comparison with change highlights.
+"""
+__all__ = ['get_close_matches', 'ndiff', 'restore', 'SequenceMatcher',
+'Differ','IS_CHARACTER_JUNK', 'IS_LINE_JUNK', 'context_diff',
+'unified_diff', 'HtmlDiff', 'Match']
+import heapq
+from collections import namedtuple as _namedtuple
+from functools import reduce
+Match = _namedtuple('Match', 'a b size')
+def _calculate_ratio(matches, length):
+if length:
+return 2.0 * matches / length
+return 1.0
+class SequenceMatcher:
+"""
+SequenceMatcher is a flexible class for comparing pairs of sequences of
+any type, so long as the sequence elements are hashable.  The basic
+algorithm predates, and is a little fancier than, an algorithm
+published in the late 1980's by Ratcliff and Obershelp under the
+hyperbolic name "gestalt pattern matching".  The basic idea is to find
+the longest contiguous matching subsequence that contains no "junk"
+elements (R-O doesn't address junk).  The same idea is then applied
+recursively to the pieces of the sequences to the left and to the right
+of the matching subsequence.  This does not yield minimal edit
+sequences, but does tend to yield matches that "look right" to people.
+SequenceMatcher tries to compute a "human-friendly diff" between two
+sequences.  Unlike e.g. UNIX(tm) diff, the fundamental notion is the
+longest *contiguous* & junk-free matching subsequence.  That's what
+catches peoples' eyes.  The Windows(tm) windiff has another interesting
+notion, pairing up elements that appear uniquely in each sequence.
+That, and the method here, appear to yield more intuitive difference
+reports than does diff.  This method appears to be the least vulnerable
+to synching up on blocks of "junk lines", though (like blank lines in
+ordinary text files, or maybe "<P>" lines in HTML files).  That may be
+because this is the only method of the 3 that has a *concept* of
+"junk" <wink>.
+Example, comparing two strings, and considering blanks to be "junk":
+>>> s = SequenceMatcher(lambda x: x == " ",
+...                     "private Thread currentThread;",
+...                     "private volatile Thread currentThread;")
+>>>
+.ratio() returns a float in [0, 1], measuring the "similarity" of the
+sequences.  As a rule of thumb, a .ratio() value over 0.6 means the
+sequences are close matches:
+>>> print round(s.ratio(), 3)
+0.866
+>>>
+If you're only interested in where the sequences match,
+.get_matching_blocks() is handy:
+>>> for block in s.get_matching_blocks():
+...     print "a[%d] and b[%d] match for %d elements" % block
+a[0] and b[0] match for 8 elements
+a[8] and b[17] match for 21 elements
+a[29] and b[38] match for 0 elements
+Note that the last tuple returned by .get_matching_blocks() is always a
+dummy, (len(a), len(b), 0), and this is the only case in which the last
+tuple element (number of elements matched) is 0.
+If you want to know how to change the first sequence into the second,
+use .get_opcodes():
+>>> for opcode in s.get_opcodes():
+...     print "%6s a[%d:%d] b[%d:%d]" % opcode
+equal a[0:8] b[0:8]
+insert a[8:8] b[8:17]
+equal a[8:29] b[17:38]
+See the Differ class for a fancy human-friendly file differencer, which
+uses SequenceMatcher both to compare sequences of lines, and to compare
+sequences of characters within similar (near-matching) lines.
+See also function get_close_matches() in this module, which shows how
+simple code building on SequenceMatcher can be used to do useful work.
+Timing:  Basic R-O is cubic time worst case and quadratic time expected
+case.  SequenceMatcher is quadratic time for the worst case and has
+expected-case behavior dependent in a complicated way on how many
+elements the sequences have in common; best case time is linear.
+Methods:
+__init__(isjunk=None, a='', b='')
+Construct a SequenceMatcher.
+set_seqs(a, b)
+Set the two sequences to be compared.
+set_seq1(a)
+Set the first sequence to be compared.
+set_seq2(b)
+Set the second sequence to be compared.
+find_longest_match(alo, ahi, blo, bhi)
+Find longest matching block in a[alo:ahi] and b[blo:bhi].
+get_matching_blocks()
+Return list of triples describing matching subsequences.
+get_opcodes()
+Return list of 5-tuples describing how to turn a into b.
+ratio()
+Return a measure of the sequences' similarity (float in [0,1]).
+quick_ratio()
+Return an upper bound on .ratio() relatively quickly.
+real_quick_ratio()
+Return an upper bound on ratio() very quickly.
+"""
+def __init__(self, isjunk=None, a='', b=''):
+"""Construct a SequenceMatcher.
+Optional arg isjunk is None (the default), or a one-argument
+function that takes a sequence element and returns true iff the
+element is junk.  None is equivalent to passing "lambda x: 0", i.e.
+no elements are considered to be junk.  For example, pass
+lambda x: x in " \\t"
+if you're comparing lines as sequences of characters, and don't
+want to synch up on blanks or hard tabs.
+Optional arg a is the first of two sequences to be compared.  By
+default, an empty string.  The elements of a must be hashable.  See
+also .set_seqs() and .set_seq1().
+Optional arg b is the second of two sequences to be compared.  By
+default, an empty string.  The elements of b must be hashable. See
+also .set_seqs() and .set_seq2().
+"""
+# Members:
+# a
+#      first sequence
+# b
+#      second sequence; differences are computed as "what do
+#      we need to do to 'a' to change it into 'b'?"
+# b2j
+#      for x in b, b2j[x] is a list of the indices (into b)
+#      at which x appears; junk elements do not appear
+# fullbcount
+#      for x in b, fullbcount[x] == the number of times x
+#      appears in b; only materialized if really needed (used
+#      only for computing quick_ratio())
+# matching_blocks
+#      a list of (i, j, k) triples, where a[i:i+k] == b[j:j+k];
+#      ascending & non-overlapping in i and in j; terminated by
+#      a dummy (len(a), len(b), 0) sentinel
+# opcodes
+#      a list of (tag, i1, i2, j1, j2) tuples, where tag is
+#      one of
+#          'replace'   a[i1:i2] should be replaced by b[j1:j2]
+#          'delete'    a[i1:i2] should be deleted
+#          'insert'    b[j1:j2] should be inserted
+#          'equal'     a[i1:i2] == b[j1:j2]
+# isjunk
+#      a user-supplied function taking a sequence element and
+#      returning true iff the element is "junk" -- this has
+#      subtle but helpful effects on the algorithm, which I'll
+#      get around to writing up someday <0.9 wink>.
+#      DON'T USE!  Only __chain_b uses this.  Use isbjunk.
+# isbjunk
+#      for x in b, isbjunk(x) == isjunk(x) but much faster;
+#      it's really the __contains__ method of a hidden dict.
+#      DOES NOT WORK for x in a!
+# isbpopular
+#      for x in b, isbpopular(x) is true iff b is reasonably long
+#      (at least 200 elements) and x accounts for more than 1% of
+#      its elements.  DOES NOT WORK for x in a!
+self.isjunk = isjunk
+self.a = self.b = None
+self.set_seqs(a, b)
+def set_seqs(self, a, b):
+"""Set the two sequences to be compared.
+>>> s = SequenceMatcher()
+>>> s.set_seqs("abcd", "bcde")
+>>> s.ratio()
+0.75
+"""
+self.set_seq1(a)
+self.set_seq2(b)
+def set_seq1(self, a):
+"""Set the first sequence to be compared.
+The second sequence to be compared is not changed.
+>>> s = SequenceMatcher(None, "abcd", "bcde")
+>>> s.ratio()
+0.75
+>>> s.set_seq1("bcde")
+>>> s.ratio()
+1.0
+>>>
+SequenceMatcher computes and caches detailed information about the
+second sequence, so if you want to compare one sequence S against
+many sequences, use .set_seq2(S) once and call .set_seq1(x)
+repeatedly for each of the other sequences.
+See also set_seqs() and set_seq2().
+"""
+if a is self.a:
+return
+self.a = a
+self.matching_blocks = self.opcodes = None
+def set_seq2(self, b):
+"""Set the second sequence to be compared.
+The first sequence to be compared is not changed.
+>>> s = SequenceMatcher(None, "abcd", "bcde")
+>>> s.ratio()
+0.75
+>>> s.set_seq2("abcd")
+>>> s.ratio()
+1.0
+>>>
+SequenceMatcher computes and caches detailed information about the
+second sequence, so if you want to compare one sequence S against
+many sequences, use .set_seq2(S) once and call .set_seq1(x)
+repeatedly for each of the other sequences.
+See also set_seqs() and set_seq1().
+"""
+if b is self.b:
+return
+self.b = b
+self.matching_blocks = self.opcodes = None
+self.fullbcount = None
+self.__chain_b()
+# For each element x in b, set b2j[x] to a list of the indices in
+# b where x appears; the indices are in increasing order; note that
+# the number of times x appears in b is len(b2j[x]) ...
+# when self.isjunk is defined, junk elements don't show up in this
+# map at all, which stops the central find_longest_match method
+# from starting any matching block at a junk element ...
+# also creates the fast isbjunk function ...
+# b2j also does not contain entries for "popular" elements, meaning
+# elements that account for more than 1% of the total elements, and
+# when the sequence is reasonably large (>= 200 elements); this can
+# be viewed as an adaptive notion of semi-junk, and yields an enormous
+# speedup when, e.g., comparing program files with hundreds of
+# instances of "return NULL;" ...
+# note that this is only called when b changes; so for cross-product
+# kinds of matches, it's best to call set_seq2 once, then set_seq1
+# repeatedly
+def __chain_b(self):
+# Because isjunk is a user-defined (not C) function, and we test
+# for junk a LOT, it's important to minimize the number of calls.
+# Before the tricks described here, __chain_b was by far the most
+# time-consuming routine in the whole module!  If anyone sees
+# Jim Roskind, thank him again for profile.py -- I never would
+# have guessed that.
+# The first trick is to build b2j ignoring the possibility
+# of junk.  I.e., we don't call isjunk at all yet.  Throwing
+# out the junk later is much cheaper than building b2j "right"
+# from the start.
+b = self.b
+n = len(b)
+self.b2j = b2j = {}
+populardict = {}
+for i, elt in enumerate(b):
+if elt in b2j:
+indices = b2j[elt]
+if n >= 200 and len(indices) * 100 > n:
+populardict[elt] = 1
+del indices[:]
+else:
+indices.append(i)
+else:
+b2j[elt] = [i]
+# Purge leftover indices for popular elements.
+for elt in populardict:
+del b2j[elt]
+# Now b2j.keys() contains elements uniquely, and especially when
+# the sequence is a string, that's usually a good deal smaller
+# than len(string).  The difference is the number of isjunk calls
+# saved.
+isjunk = self.isjunk
+junkdict = {}
+if isjunk:
+for d in populardict, b2j:
+for elt in d.keys():
+if isjunk(elt):
+junkdict[elt] = 1
+del d[elt]
+# Now for x in b, isjunk(x) == x in junkdict, but the
+# latter is much faster.  Note too that while there may be a
+# lot of junk in the sequence, the number of *unique* junk
+# elements is probably small.  So the memory burden of keeping
+# this dict alive is likely trivial compared to the size of b2j.
+self.isbjunk = junkdict.__contains__
+self.isbpopular = populardict.__contains__
+def find_longest_match(self, alo, ahi, blo, bhi):
+"""Find longest matching block in a[alo:ahi] and b[blo:bhi].
+If isjunk is not defined:
+Return (i,j,k) such that a[i:i+k] is equal to b[j:j+k], where
+alo <= i <= i+k <= ahi
+blo <= j <= j+k <= bhi
+and for all (i',j',k') meeting those conditions,
+k >= k'
+i <= i'
+and if i == i', j <= j'
+In other words, of all maximal matching blocks, return one that
+starts earliest in a, and of all those maximal matching blocks that
+start earliest in a, return the one that starts earliest in b.
+>>> s = SequenceMatcher(None, " abcd", "abcd abcd")
+>>> s.find_longest_match(0, 5, 0, 9)
+Match(a=0, b=4, size=5)
+If isjunk is defined, first the longest matching block is
+determined as above, but with the additional restriction that no
+junk element appears in the block.  Then that block is extended as
+far as possible by matching (only) junk elements on both sides.  So
+the resulting block never matches on junk except as identical junk
+happens to be adjacent to an "interesting" match.
+Here's the same example as before, but considering blanks to be
+junk.  That prevents " abcd" from matching the " abcd" at the tail
+end of the second sequence directly.  Instead only the "abcd" can
+match, and matches the leftmost "abcd" in the second sequence:
+>>> s = SequenceMatcher(lambda x: x==" ", " abcd", "abcd abcd")
+>>> s.find_longest_match(0, 5, 0, 9)
+Match(a=1, b=0, size=4)
+If no blocks match, return (alo, blo, 0).
+>>> s = SequenceMatcher(None, "ab", "c")
+>>> s.find_longest_match(0, 2, 0, 1)
+Match(a=0, b=0, size=0)
+"""
+# CAUTION:  stripping common prefix or suffix would be incorrect.
+# E.g.,
+#    ab
+#    acab
+# Longest matching block is "ab", but if common prefix is
+# stripped, it's "a" (tied with "b").  UNIX(tm) diff does so
+# strip, so ends up claiming that ab is changed to acab by
+# inserting "ca" in the middle.  That's minimal but unintuitive:
+# "it's obvious" that someone inserted "ac" at the front.
+# Windiff ends up at the same place as diff, but by pairing up
+# the unique 'b's and then matching the first two 'a's.
+a, b, b2j, isbjunk = self.a, self.b, self.b2j, self.isbjunk
+besti, bestj, bestsize = alo, blo, 0
+# find longest junk-free match
+# during an iteration of the loop, j2len[j] = length of longest
+# junk-free match ending with a[i-1] and b[j]
+j2len = {}
+nothing = []
+for i in xrange(alo, ahi):
+# look at all instances of a[i] in b; note that because
+# b2j has no junk keys, the loop is skipped if a[i] is junk
+j2lenget = j2len.get
+newj2len = {}
+for j in b2j.get(a[i], nothing):
+# a[i] matches b[j]
+if j < blo:
+continue
+if j >= bhi:
+break
+k = newj2len[j] = j2lenget(j-1, 0) + 1
+if k > bestsize:
+besti, bestj, bestsize = i-k+1, j-k+1, k
+j2len = newj2len
+# Extend the best by non-junk elements on each end.  In particular,
+# "popular" non-junk elements aren't in b2j, which greatly speeds
+# the inner loop above, but also means "the best" match so far
+# doesn't contain any junk *or* popular non-junk elements.
+while besti > alo and bestj > blo and \
+not isbjunk(b[bestj-1]) and \
+a[besti-1] == b[bestj-1]:
+besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
+while besti+bestsize < ahi and bestj+bestsize < bhi and \
+not isbjunk(b[bestj+bestsize]) and \
+a[besti+bestsize] == b[bestj+bestsize]:
+bestsize += 1
+# Now that we have a wholly interesting match (albeit possibly
+# empty!), we may as well suck up the matching junk on each
+# side of it too.  Can't think of a good reason not to, and it
+# saves post-processing the (possibly considerable) expense of
+# figuring out what to do with it.  In the case of an empty
+# interesting match, this is clearly the right thing to do,
+# because no other kind of match is possible in the regions.
+while besti > alo and bestj > blo and \
+isbjunk(b[bestj-1]) and \
+a[besti-1] == b[bestj-1]:
+besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
+while besti+bestsize < ahi and bestj+bestsize < bhi and \
+isbjunk(b[bestj+bestsize]) and \
+a[besti+bestsize] == b[bestj+bestsize]:
+bestsize = bestsize + 1
+return Match(besti, bestj, bestsize)
+def get_matching_blocks(self):
+"""Return list of triples describing matching subsequences.
+Each triple is of the form (i, j, n), and means that
+a[i:i+n] == b[j:j+n].  The triples are monotonically increasing in
+i and in j.  New in Python 2.5, it's also guaranteed that if
+(i, j, n) and (i', j', n') are adjacent triples in the list, and
+the second is not the last triple in the list, then i+n != i' or
+j+n != j'.  IOW, adjacent triples never describe adjacent equal
+blocks.
+The last triple is a dummy, (len(a), len(b), 0), and is the only
+triple with n==0.
+>>> s = SequenceMatcher(None, "abxcd", "abcd")
+>>> s.get_matching_blocks()
+[Match(a=0, b=0, size=2), Match(a=3, b=2, size=2), Match(a=5, b=4, size=0)]
+"""
+if self.matching_blocks is not None:
+return self.matching_blocks
+la, lb = len(self.a), len(self.b)
+# This is most naturally expressed as a recursive algorithm, but
+# at least one user bumped into extreme use cases that exceeded
+# the recursion limit on their box.  So, now we maintain a list
+# ('queue`) of blocks we still need to look at, and append partial
+# results to `matching_blocks` in a loop; the matches are sorted
+# at the end.
+queue = [(0, la, 0, lb)]
+matching_blocks = []
+while queue:
+alo, ahi, blo, bhi = queue.pop()
+i, j, k = x = self.find_longest_match(alo, ahi, blo, bhi)
+# a[alo:i] vs b[blo:j] unknown
+# a[i:i+k] same as b[j:j+k]
+# a[i+k:ahi] vs b[j+k:bhi] unknown
+if k:   # if k is 0, there was no matching block
+matching_blocks.append(x)
+if alo < i and blo < j:
+queue.append((alo, i, blo, j))
+if i+k < ahi and j+k < bhi:
+queue.append((i+k, ahi, j+k, bhi))
+matching_blocks.sort()
+# It's possible that we have adjacent equal blocks in the
+# matching_blocks list now.  Starting with 2.5, this code was added
+# to collapse them.
+i1 = j1 = k1 = 0
+non_adjacent = []
+for i2, j2, k2 in matching_blocks:
+# Is this block adjacent to i1, j1, k1?
+if i1 + k1 == i2 and j1 + k1 == j2:
+# Yes, so collapse them -- this just increases the length of
+# the first block by the length of the second, and the first
+# block so lengthened remains the block to compare against.
+k1 += k2
+else:
+# Not adjacent.  Remember the first block (k1==0 means it's
+# the dummy we started with), and make the second block the
+# new block to compare against.
+if k1:
+non_adjacent.append((i1, j1, k1))
+i1, j1, k1 = i2, j2, k2
+if k1:
+non_adjacent.append((i1, j1, k1))
+non_adjacent.append( (la, lb, 0) )
+self.matching_blocks = non_adjacent
+return map(Match._make, self.matching_blocks)
+def get_opcodes(self):
+"""Return list of 5-tuples describing how to turn a into b.
+Each tuple is of the form (tag, i1, i2, j1, j2).  The first tuple
+has i1 == j1 == 0, and remaining tuples have i1 == the i2 from the
+tuple preceding it, and likewise for j1 == the previous j2.
+The tags are strings, with these meanings:
+'replace':  a[i1:i2] should be replaced by b[j1:j2]
+'delete':   a[i1:i2] should be deleted.
+Note that j1==j2 in this case.
+'insert':   b[j1:j2] should be inserted at a[i1:i1].
+Note that i1==i2 in this case.
+'equal':    a[i1:i2] == b[j1:j2]
+>>> a = "qabxcd"
+>>> b = "abycdf"
+>>> s = SequenceMatcher(None, a, b)
+>>> for tag, i1, i2, j1, j2 in s.get_opcodes():
+...    print ("%7s a[%d:%d] (%s) b[%d:%d] (%s)" %
+...           (tag, i1, i2, a[i1:i2], j1, j2, b[j1:j2]))
+delete a[0:1] (q) b[0:0] ()
+equal a[1:3] (ab) b[0:2] (ab)
+replace a[3:4] (x) b[2:3] (y)
+equal a[4:6] (cd) b[3:5] (cd)
+insert a[6:6] () b[5:6] (f)
+"""
+if self.opcodes is not None:
+return self.opcodes
+i = j = 0
+self.opcodes = answer = []
+for ai, bj, size in self.get_matching_blocks():
+# invariant:  we've pumped out correct diffs to change
+# a[:i] into b[:j], and the next matching block is
+# a[ai:ai+size] == b[bj:bj+size].  So we need to pump
+# out a diff to change a[i:ai] into b[j:bj], pump out
+# the matching block, and move (i,j) beyond the match
+tag = ''
+if i < ai and j < bj:
+tag = 'replace'
+elif i < ai:
+tag = 'delete'
+elif j < bj:
+tag = 'insert'
+if tag:
+answer.append( (tag, i, ai, j, bj) )
+i, j = ai+size, bj+size
+# the list of matching blocks is terminated by a
+# sentinel with size 0
+if size:
+answer.append( ('equal', ai, i, bj, j) )
+return answer
+def get_grouped_opcodes(self, n=3):
+""" Isolate change clusters by eliminating ranges with no changes.
+Return a generator of groups with upto n lines of context.
+Each group is in the same format as returned by get_opcodes().
+>>> from pprint import pprint
+>>> a = map(str, range(1,40))
+>>> b = a[:]
+>>> b[8:8] = ['i']     # Make an insertion
+>>> b[20] += 'x'       # Make a replacement
+>>> b[23:28] = []      # Make a deletion
+>>> b[30] += 'y'       # Make another replacement
+>>> pprint(list(SequenceMatcher(None,a,b).get_grouped_opcodes()))
+[[('equal', 5, 8, 5, 8), ('insert', 8, 8, 8, 9), ('equal', 8, 11, 9, 12)],
+[('equal', 16, 19, 17, 20),
+('replace', 19, 20, 20, 21),
+('equal', 20, 22, 21, 23),
+('delete', 22, 27, 23, 23),
+('equal', 27, 30, 23, 26)],
+[('equal', 31, 34, 27, 30),
+('replace', 34, 35, 30, 31),
+('equal', 35, 38, 31, 34)]]
+"""
+codes = self.get_opcodes()
+if not codes:
+codes = [("equal", 0, 1, 0, 1)]
+# Fixup leading and trailing groups if they show no changes.
+if codes[0][0] == 'equal':
+tag, i1, i2, j1, j2 = codes[0]
+codes[0] = tag, max(i1, i2-n), i2, max(j1, j2-n), j2
+if codes[-1][0] == 'equal':
+tag, i1, i2, j1, j2 = codes[-1]
+codes[-1] = tag, i1, min(i2, i1+n), j1, min(j2, j1+n)
+nn = n + n
+group = []
+for tag, i1, i2, j1, j2 in codes:
+# End the current group and start a new one whenever
+# there is a large range with no changes.
+if tag == 'equal' and i2-i1 > nn:
+group.append((tag, i1, min(i2, i1+n), j1, min(j2, j1+n)))
+yield group
+group = []
+i1, j1 = max(i1, i2-n), max(j1, j2-n)
+group.append((tag, i1, i2, j1 ,j2))
+if group and not (len(group)==1 and group[0][0] == 'equal'):
+yield group
+def ratio(self):
+"""Return a measure of the sequences' similarity (float in [0,1]).
+Where T is the total number of elements in both sequences, and
+M is the number of matches, this is 2.0*M / T.
+Note that this is 1 if the sequences are identical, and 0 if
+they have nothing in common.
+.ratio() is expensive to compute if you haven't already computed
+.get_matching_blocks() or .get_opcodes(), in which case you may
+want to try .quick_ratio() or .real_quick_ratio() first to get an
+upper bound.
+>>> s = SequenceMatcher(None, "abcd", "bcde")
+>>> s.ratio()
+0.75
+>>> s.quick_ratio()
+0.75
+>>> s.real_quick_ratio()
+1.0
+"""
+matches = reduce(lambda sum, triple: sum + triple[-1],
+self.get_matching_blocks(), 0)
+return _calculate_ratio(matches, len(self.a) + len(self.b))
+def quick_ratio(self):
+"""Return an upper bound on ratio() relatively quickly.
+This isn't defined beyond that it is an upper bound on .ratio(), and
+is faster to compute.
+"""
+# viewing a and b as multisets, set matches to the cardinality
+# of their intersection; this counts the number of matches
+# without regard to order, so is clearly an upper bound
+if self.fullbcount is None:
+self.fullbcount = fullbcount = {}
+for elt in self.b:
+fullbcount[elt] = fullbcount.get(elt, 0) + 1
+fullbcount = self.fullbcount
+# avail[x] is the number of times x appears in 'b' less the
+# number of times we've seen it in 'a' so far ... kinda
+avail = {}
+availhas, matches = avail.__contains__, 0
+for elt in self.a:
+if availhas(elt):
+numb = avail[elt]
+else:
+numb = fullbcount.get(elt, 0)
+avail[elt] = numb - 1
+if numb > 0:
+matches = matches + 1
+return _calculate_ratio(matches, len(self.a) + len(self.b))
+def real_quick_ratio(self):
+"""Return an upper bound on ratio() very quickly.
+This isn't defined beyond that it is an upper bound on .ratio(), and
+is faster to compute than either .ratio() or .quick_ratio().
+"""
+la, lb = len(self.a), len(self.b)
+# can't have more matches than the number of elements in the
+# shorter sequence
+return _calculate_ratio(min(la, lb), la + lb)
+def get_close_matches(word, possibilities, n=3, cutoff=0.6):
+"""Use SequenceMatcher to return list of the best "good enough" matches.
+word is a sequence for which close matches are desired (typically a
+string).
+possibilities is a list of sequences against which to match word
+(typically a list of strings).
+Optional arg n (default 3) is the maximum number of close matches to
+return.  n must be > 0.
+Optional arg cutoff (default 0.6) is a float in [0, 1].  Possibilities
+that don't score at least that similar to word are ignored.
+The best (no more than n) matches among the possibilities are returned
+in a list, sorted by similarity score, most similar first.
+>>> get_close_matches("appel", ["ape", "apple", "peach", "puppy"])
+['apple', 'ape']
+>>> import keyword as _keyword
+>>> get_close_matches("wheel", _keyword.kwlist)
+['while']
+>>> get_close_matches("apple", _keyword.kwlist)
+[]
+>>> get_close_matches("accept", _keyword.kwlist)
+['except']
+"""
+if not n >  0:
+raise ValueError("n must be > 0: %r" % (n,))
+if not 0.0 <= cutoff <= 1.0:
+raise ValueError("cutoff must be in [0.0, 1.0]: %r" % (cutoff,))
+result = []
+s = SequenceMatcher()
+s.set_seq2(word)
+for x in possibilities:
+s.set_seq1(x)
+if s.real_quick_ratio() >= cutoff and \
+s.quick_ratio() >= cutoff and \
+s.ratio() >= cutoff:
+result.append((s.ratio(), x))
+# Move the best scorers to head of list
+result = heapq.nlargest(n, result)
+# Strip scores for the best n matches
+return [x for score, x in result]
+def _count_leading(line, ch):
+"""
+Return number of `ch` characters at the start of `line`.
+Example:
+>>> _count_leading('   abc', ' ')
+3
+"""
+i, n = 0, len(line)
+while i < n and line[i] == ch:
+i += 1
+return i
+class Differ:
+r"""
+Differ is a class for comparing sequences of lines of text, and
+producing human-readable differences or deltas.  Differ uses
+SequenceMatcher both to compare sequences of lines, and to compare
+sequences of characters within similar (near-matching) lines.
+Each line of a Differ delta begins with a two-letter code:
+'- '    line unique to sequence 1
+'+ '    line unique to sequence 2
+'  '    line common to both sequences
+'? '    line not present in either input sequence
+Lines beginning with '? ' attempt to guide the eye to intraline
+differences, and were not present in either input sequence.  These lines
+can be confusing if the sequences contain tab characters.
+Note that Differ makes no claim to produce a *minimal* diff.  To the
+contrary, minimal diffs are often counter-intuitive, because they synch
+up anywhere possible, sometimes accidental matches 100 pages apart.
+Restricting synch points to contiguous matches preserves some notion of
+locality, at the occasional cost of producing a longer diff.
+Example: Comparing two texts.
+First we set up the texts, sequences of individual single-line strings
+ending with newlines (such sequences can also be obtained from the
+`readlines()` method of file-like objects):
+>>> text1 = '''  1. Beautiful is better than ugly.
+...   2. Explicit is better than implicit.
+...   3. Simple is better than complex.
+...   4. Complex is better than complicated.
+... '''.splitlines(1)
+>>> len(text1)
+4
+>>> text1[0][-1]
+'\n'
+>>> text2 = '''  1. Beautiful is better than ugly.
+...   3.   Simple is better than complex.
+...   4. Complicated is better than complex.
+...   5. Flat is better than nested.
+... '''.splitlines(1)
+Next we instantiate a Differ object:
+>>> d = Differ()
+Note that when instantiating a Differ object we may pass functions to
+filter out line and character 'junk'.  See Differ.__init__ for details.
+Finally, we compare the two:
+>>> result = list(d.compare(text1, text2))
+'result' is a list of strings, so let's pretty-print it:
+>>> from pprint import pprint as _pprint
+>>> _pprint(result)
+['    1. Beautiful is better than ugly.\n',
+'-   2. Explicit is better than implicit.\n',
+'-   3. Simple is better than complex.\n',
+'+   3.   Simple is better than complex.\n',
+'?     ++\n',
+'-   4. Complex is better than complicated.\n',
+'?            ^                     ---- ^\n',
+'+   4. Complicated is better than complex.\n',
+'?           ++++ ^                      ^\n',
+'+   5. Flat is better than nested.\n']
+As a single multi-line string it looks like this:
+>>> print ''.join(result),
+1. Beautiful is better than ugly.
+-   2. Explicit is better than implicit.
+-   3. Simple is better than complex.
++   3.   Simple is better than complex.
+?     ++
+-   4. Complex is better than complicated.
+?            ^                     ---- ^
++   4. Complicated is better than complex.
+?           ++++ ^                      ^
++   5. Flat is better than nested.
+Methods:
+__init__(linejunk=None, charjunk=None)
+Construct a text differencer, with optional filters.
+compare(a, b)
+Compare two sequences of lines; generate the resulting delta.
+"""
+def __init__(self, linejunk=None, charjunk=None):
+"""
+Construct a text differencer, with optional filters.
+The two optional keyword parameters are for filter functions:
+- `linejunk`: A function that should accept a single string argument,
+and return true iff the string is junk. The module-level function
+`IS_LINE_JUNK` may be used to filter out lines without visible
+characters, except for at most one splat ('#').  It is recommended
+to leave linejunk None; as of Python 2.3, the underlying
+SequenceMatcher class has grown an adaptive notion of "noise" lines
+that's better than any static definition the author has ever been
+able to craft.
+- `charjunk`: A function that should accept a string of length 1. The
+module-level function `IS_CHARACTER_JUNK` may be used to filter out
+whitespace characters (a blank or tab; **note**: bad idea to include
+newline in this!).  Use of IS_CHARACTER_JUNK is recommended.
+"""
+self.linejunk = linejunk
+self.charjunk = charjunk
+def compare(self, a, b):
+r"""
+Compare two sequences of lines; generate the resulting delta.
+Each sequence must contain individual single-line strings ending with
+newlines. Such sequences can be obtained from the `readlines()` method
+of file-like objects.  The delta generated also consists of newline-
+terminated strings, ready to be printed as-is via the writeline()
+method of a file-like object.
+Example:
+>>> print ''.join(Differ().compare('one\ntwo\nthree\n'.splitlines(1),
+...                                'ore\ntree\nemu\n'.splitlines(1))),
+- one
+?  ^
++ ore
+?  ^
+- two
+- three
+?  -
++ tree
++ emu
+"""
+cruncher = SequenceMatcher(self.linejunk, a, b)
+for tag, alo, ahi, blo, bhi in cruncher.get_opcodes():
+if tag == 'replace':
+g = self._fancy_replace(a, alo, ahi, b, blo, bhi)
+elif tag == 'delete':
+g = self._dump('-', a, alo, ahi)
+elif tag == 'insert':
+g = self._dump('+', b, blo, bhi)
+elif tag == 'equal':
+g = self._dump(' ', a, alo, ahi)
+else:
+raise ValueError, 'unknown tag %r' % (tag,)
+for line in g:
+yield line
+def _dump(self, tag, x, lo, hi):
+"""Generate comparison results for a same-tagged range."""
+for i in xrange(lo, hi):
+yield '%s %s' % (tag, x[i])
+def _plain_replace(self, a, alo, ahi, b, blo, bhi):
+assert alo < ahi and blo < bhi
+# dump the shorter block first -- reduces the burden on short-term
+# memory if the blocks are of very different sizes
+if bhi - blo < ahi - alo:
+first  = self._dump('+', b, blo, bhi)
+second = self._dump('-', a, alo, ahi)
+else:
+first  = self._dump('-', a, alo, ahi)
+second = self._dump('+', b, blo, bhi)
+for g in first, second:
+for line in g:
+yield line
+def _fancy_replace(self, a, alo, ahi, b, blo, bhi):
+r"""
+When replacing one block of lines with another, search the blocks
+for *similar* lines; the best-matching pair (if any) is used as a
+synch point, and intraline difference marking is done on the
+similar pair. Lots of work, but often worth it.
+Example:
+>>> d = Differ()
+>>> results = d._fancy_replace(['abcDefghiJkl\n'], 0, 1,
+...                            ['abcdefGhijkl\n'], 0, 1)
+>>> print ''.join(results),
+- abcDefghiJkl
+?    ^  ^  ^
++ abcdefGhijkl
+?    ^  ^  ^
+"""
+# don't synch up unless the lines have a similarity score of at
+# least cutoff; best_ratio tracks the best score seen so far
+best_ratio, cutoff = 0.74, 0.75
+cruncher = SequenceMatcher(self.charjunk)
+eqi, eqj = None, None   # 1st indices of equal lines (if any)
+# search for the pair that matches best without being identical
+# (identical lines must be junk lines, & we don't want to synch up
+# on junk -- unless we have to)
+for j in xrange(blo, bhi):
+bj = b[j]
+cruncher.set_seq2(bj)
+for i in xrange(alo, ahi):
+ai = a[i]
+if ai == bj:
+if eqi is None:
+eqi, eqj = i, j
+continue
+cruncher.set_seq1(ai)
+# computing similarity is expensive, so use the quick
+# upper bounds first -- have seen this speed up messy
+# compares by a factor of 3.
+# note that ratio() is only expensive to compute the first
+# time it's called on a sequence pair; the expensive part
+# of the computation is cached by cruncher
+if cruncher.real_quick_ratio() > best_ratio and \
+cruncher.quick_ratio() > best_ratio and \
+cruncher.ratio() > best_ratio:
+best_ratio, best_i, best_j = cruncher.ratio(), i, j
+if best_ratio < cutoff:
+# no non-identical "pretty close" pair
+if eqi is None:
+# no identical pair either -- treat it as a straight replace
+for line in self._plain_replace(a, alo, ahi, b, blo, bhi):
+yield line
+return
+# no close pair, but an identical pair -- synch up on that
+best_i, best_j, best_ratio = eqi, eqj, 1.0
+else:
+# there's a close pair, so forget the identical pair (if any)
+eqi = None
+# a[best_i] very similar to b[best_j]; eqi is None iff they're not
+# identical
+# pump out diffs from before the synch point
+for line in self._fancy_helper(a, alo, best_i, b, blo, best_j):
+yield line
+# do intraline marking on the synch pair
+aelt, belt = a[best_i], b[best_j]
+if eqi is None:
+# pump out a '-', '?', '+', '?' quad for the synched lines
+atags = btags = ""
+cruncher.set_seqs(aelt, belt)
+for tag, ai1, ai2, bj1, bj2 in cruncher.get_opcodes():
+la, lb = ai2 - ai1, bj2 - bj1
+if tag == 'replace':
+atags += '^' * la
+btags += '^' * lb
+elif tag == 'delete':
+atags += '-' * la
+elif tag == 'insert':
+btags += '+' * lb
+elif tag == 'equal':
+atags += ' ' * la
+btags += ' ' * lb
+else:
+raise ValueError, 'unknown tag %r' % (tag,)
+for line in self._qformat(aelt, belt, atags, btags):
+yield line
+else:
+# the synch pair is identical
+yield '  ' + aelt
+# pump out diffs from after the synch point
+for line in self._fancy_helper(a, best_i+1, ahi, b, best_j+1, bhi):
+yield line
+def _fancy_helper(self, a, alo, ahi, b, blo, bhi):
+g = []
+if alo < ahi:
+if blo < bhi:
+g = self._fancy_replace(a, alo, ahi, b, blo, bhi)
+else:
+g = self._dump('-', a, alo, ahi)
+elif blo < bhi:
+g = self._dump('+', b, blo, bhi)
+for line in g:
+yield line
+def _qformat(self, aline, bline, atags, btags):
+r"""
+Format "?" output and deal with leading tabs.
+Example:
+>>> d = Differ()
+>>> results = d._qformat('\tabcDefghiJkl\n', '\t\tabcdefGhijkl\n',
+...                      '  ^ ^  ^      ', '+  ^ ^  ^      ')
+>>> for line in results: print repr(line)
+...
+'- \tabcDefghiJkl\n'
+'? \t ^ ^  ^\n'
+'+ \t\tabcdefGhijkl\n'
+'? \t  ^ ^  ^\n'
+"""
+# Can hurt, but will probably help most of the time.
+common = min(_count_leading(aline, "\t"),
+_count_leading(bline, "\t"))
+common = min(common, _count_leading(atags[:common], " "))
+atags = atags[common:].rstrip()
+btags = btags[common:].rstrip()
+yield "- " + aline
+if atags:
+yield "? %s%s\n" % ("\t" * common, atags)
+yield "+ " + bline
+if btags:
+yield "? %s%s\n" % ("\t" * common, btags)
+# With respect to junk, an earlier version of ndiff simply refused to
+# *start* a match with a junk element.  The result was cases like this:
+#     before: private Thread currentThread;
+#     after:  private volatile Thread currentThread;
+# If you consider whitespace to be junk, the longest contiguous match
+# not starting with junk is "e Thread currentThread".  So ndiff reported
+# that "e volatil" was inserted between the 't' and the 'e' in "private".
+# While an accurate view, to people that's absurd.  The current version
+# looks for matching blocks that are entirely junk-free, then extends the
+# longest one of those as far as possible but only with matching junk.
+# So now "currentThread" is matched, then extended to suck up the
+# preceding blank; then "private" is matched, and extended to suck up the
+# following blank; then "Thread" is matched; and finally ndiff reports
+# that "volatile " was inserted before "Thread".  The only quibble
+# remaining is that perhaps it was really the case that " volatile"
+# was inserted after "private".  I can live with that <wink>.
+import re
+def IS_LINE_JUNK(line, pat=re.compile(r"\s*#?\s*$").match):
+r"""
+Return 1 for ignorable line: iff `line` is blank or contains a single '#'.
+Examples:
+>>> IS_LINE_JUNK('\n')
+True
+>>> IS_LINE_JUNK('  #   \n')
+True
+>>> IS_LINE_JUNK('hello\n')
+False
+"""
+return pat(line) is not None
+def IS_CHARACTER_JUNK(ch, ws=" \t"):
+r"""
+Return 1 for ignorable character: iff `ch` is a space or tab.
+Examples:
+>>> IS_CHARACTER_JUNK(' ')
+True
+>>> IS_CHARACTER_JUNK('\t')
+True
+>>> IS_CHARACTER_JUNK('\n')
+False
+>>> IS_CHARACTER_JUNK('x')
+False
+"""
+return ch in ws
+def unified_diff(a, b, fromfile='', tofile='', fromfiledate='',
+tofiledate='', n=3, lineterm='\n'):
+r"""
+Compare two sequences of lines; generate the delta as a unified diff.
+Unified diffs are a compact way of showing line changes and a few
+lines of context.  The number of context lines is set by 'n' which
+defaults to three.
+By default, the diff control lines (those with ---, +++, or @@) are
+created with a trailing newline.  This is helpful so that inputs
+created from file.readlines() result in diffs that are suitable for
+file.writelines() since both the inputs and outputs have trailing
+newlines.
+For inputs that do not have trailing newlines, set the lineterm
+argument to "" so that the output will be uniformly newline free.
+The unidiff format normally has a header for filenames and modification
+times.  Any or all of these may be specified using strings for
+'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.  The modification
+times are normally expressed in the format returned by time.ctime().
+Example:
+>>> for line in unified_diff('one two three four'.split(),
+...             'zero one tree four'.split(), 'Original', 'Current',
+...             'Sat Jan 26 23:30:50 1991', 'Fri Jun 06 10:20:52 2003',
+...             lineterm=''):
+...     print line
+--- Original Sat Jan 26 23:30:50 1991
++++ Current Fri Jun 06 10:20:52 2003
+@@ -1,4 +1,4 @@
++zero
+one
+-two
+-three
++tree
+four
+"""
+started = False
+for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n):
+if not started:
+yield '--- %s %s%s' % (fromfile, fromfiledate, lineterm)
+yield '+++ %s %s%s' % (tofile, tofiledate, lineterm)
+started = True
+i1, i2, j1, j2 = group[0][1], group[-1][2], group[0][3], group[-1][4]
+yield "@@ -%d,%d +%d,%d @@%s" % (i1+1, i2-i1, j1+1, j2-j1, lineterm)
+for tag, i1, i2, j1, j2 in group:
+if tag == 'equal':
+for line in a[i1:i2]:
+yield ' ' + line
+continue
+if tag == 'replace' or tag == 'delete':
+for line in a[i1:i2]:
+yield '-' + line
+if tag == 'replace' or tag == 'insert':
+for line in b[j1:j2]:
+yield '+' + line
+# See http://www.unix.org/single_unix_specification/
+def context_diff(a, b, fromfile='', tofile='',
+fromfiledate='', tofiledate='', n=3, lineterm='\n'):
+r"""
+Compare two sequences of lines; generate the delta as a context diff.
+Context diffs are a compact way of showing line changes and a few
+lines of context.  The number of context lines is set by 'n' which
+defaults to three.
+By default, the diff control lines (those with *** or ---) are
+created with a trailing newline.  This is helpful so that inputs
+created from file.readlines() result in diffs that are suitable for
+file.writelines() since both the inputs and outputs have trailing
+newlines.
+For inputs that do not have trailing newlines, set the lineterm
+argument to "" so that the output will be uniformly newline free.
+The context diff format normally has a header for filenames and
+modification times.  Any or all of these may be specified using
+strings for 'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.
+The modification times are normally expressed in the format returned
+by time.ctime().  If not specified, the strings default to blanks.
+Example:
+>>> print ''.join(context_diff('one\ntwo\nthree\nfour\n'.splitlines(1),
+...       'zero\none\ntree\nfour\n'.splitlines(1), 'Original', 'Current',
+...       'Sat Jan 26 23:30:50 1991', 'Fri Jun 06 10:22:46 2003')),
+*** Original Sat Jan 26 23:30:50 1991
+--- Current Fri Jun 06 10:22:46 2003
+***************
+*** 1,4 ****
+one
+! two
+! three
+four
+--- 1,4 ----
++ zero
+one
+! tree
+four
+"""
+started = False
+prefixmap = {'insert':'+ ', 'delete':'- ', 'replace':'! ', 'equal':'  '}
+for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n):
+if not started:
+yield '*** %s %s%s' % (fromfile, fromfiledate, lineterm)
+yield '--- %s %s%s' % (tofile, tofiledate, lineterm)
+started = True
+yield '***************%s' % (lineterm,)
+if group[-1][2] - group[0][1] >= 2:
+yield '*** %d,%d ****%s' % (group[0][1]+1, group[-1][2], lineterm)
+else:
+yield '*** %d ****%s' % (group[-1][2], lineterm)
+visiblechanges = [e for e in group if e[0] in ('replace', 'delete')]
+if visiblechanges:
+for tag, i1, i2, _, _ in group:
+if tag != 'insert':
+for line in a[i1:i2]:
+yield prefixmap[tag] + line
+if group[-1][4] - group[0][3] >= 2:
+yield '--- %d,%d ----%s' % (group[0][3]+1, group[-1][4], lineterm)
+else:
+yield '--- %d ----%s' % (group[-1][4], lineterm)
+visiblechanges = [e for e in group if e[0] in ('replace', 'insert')]
+if visiblechanges:
+for tag, _, _, j1, j2 in group:
+if tag != 'delete':
+for line in b[j1:j2]:
+yield prefixmap[tag] + line
+def ndiff(a, b, linejunk=None, charjunk=IS_CHARACTER_JUNK):
+r"""
+Compare `a` and `b` (lists of strings); return a `Differ`-style delta.
+Optional keyword parameters `linejunk` and `charjunk` are for filter
+functions (or None):
+- linejunk: A function that should accept a single string argument, and
+return true iff the string is junk.  The default is None, and is
+recommended; as of Python 2.3, an adaptive notion of "noise" lines is
+used that does a good job on its own.
+- charjunk: A function that should accept a string of length 1. The
+default is module-level function IS_CHARACTER_JUNK, which filters out
+whitespace characters (a blank or tab; note: bad idea to include newline
+in this!).
+Tools/scripts/ndiff.py is a command-line front-end to this function.
+Example:
+>>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1),
+...              'ore\ntree\nemu\n'.splitlines(1))
+>>> print ''.join(diff),
+- one
+?  ^
++ ore
+?  ^
+- two
+- three
+?  -
++ tree
++ emu
+"""
+return Differ(linejunk, charjunk).compare(a, b)
+def _mdiff(fromlines, tolines, context=None, linejunk=None,
+charjunk=IS_CHARACTER_JUNK):
+r"""Returns generator yielding marked up from/to side by side differences.
+Arguments:
+fromlines -- list of text lines to compared to tolines
+tolines -- list of text lines to be compared to fromlines
+context -- number of context lines to display on each side of difference,
+if None, all from/to text lines will be generated.
+linejunk -- passed on to ndiff (see ndiff documentation)
+charjunk -- passed on to ndiff (see ndiff documentation)
+This function returns an interator which returns a tuple:
+(from line tuple, to line tuple, boolean flag)
+from/to line tuple -- (line num, line text)
+line num -- integer or None (to indicate a context seperation)
+line text -- original line text with following markers inserted:
+'\0+' -- marks start of added text
+'\0-' -- marks start of deleted text
+'\0^' -- marks start of changed text
+'\1' -- marks end of added/deleted/changed text
+boolean flag -- None indicates context separation, True indicates
+either "from" or "to" line contains a change, otherwise False.
+This function/iterator was originally developed to generate side by side
+file difference for making HTML pages (see HtmlDiff class for example
+usage).
+Note, this function utilizes the ndiff function to generate the side by
+side difference markup.  Optional ndiff arguments may be passed to this
+function and they in turn will be passed to ndiff.
+"""
+import re
+# regular expression for finding intraline change indices
+change_re = re.compile('(\++|\-+|\^+)')
+# create the difference iterator to generate the differences
+diff_lines_iterator = ndiff(fromlines,tolines,linejunk,charjunk)
+def _make_line(lines, format_key, side, num_lines=[0,0]):
+"""Returns line of text with user's change markup and line formatting.
+lines -- list of lines from the ndiff generator to produce a line of
+text from.  When producing the line of text to return, the
+lines used are removed from this list.
+format_key -- '+' return first line in list with "add" markup around
+the entire line.
+'-' return first line in list with "delete" markup around
+the entire line.
+'?' return first line in list with add/delete/change
+intraline markup (indices obtained from second line)
+None return first line in list with no markup
+side -- indice into the num_lines list (0=from,1=to)
+num_lines -- from/to current line number.  This is NOT intended to be a
+passed parameter.  It is present as a keyword argument to
+maintain memory of the current line numbers between calls
+of this function.
+Note, this function is purposefully not defined at the module scope so
+that data it needs from its parent function (within whose context it
+is defined) does not need to be of module scope.
+"""
+num_lines[side] += 1
+# Handle case where no user markup is to be added, just return line of
+# text with user's line format to allow for usage of the line number.
+if format_key is None:
+return (num_lines[side],lines.pop(0)[2:])
+# Handle case of intraline changes
+if format_key == '?':
+text, markers = lines.pop(0), lines.pop(0)
+# find intraline changes (store change type and indices in tuples)
+sub_info = []
+def record_sub_info(match_object,sub_info=sub_info):
+sub_info.append([match_object.group(1)[0],match_object.span()])
+return match_object.group(1)
+change_re.sub(record_sub_info,markers)
+# process each tuple inserting our special marks that won't be
+# noticed by an xml/html escaper.
+for key,(begin,end) in sub_info[::-1]:
+text = text[0:begin]+'\0'+key+text[begin:end]+'\1'+text[end:]
+text = text[2:]
+# Handle case of add/delete entire line
+else:
+text = lines.pop(0)[2:]
+# if line of text is just a newline, insert a space so there is
+# something for the user to highlight and see.
+if not text:
+text = ' '
+# insert marks that won't be noticed by an xml/html escaper.
+text = '\0' + format_key + text + '\1'
+# Return line of text, first allow user's line formatter to do its
+# thing (such as adding the line number) then replace the special
+# marks with what the user's change markup.
+return (num_lines[side],text)
+def _line_iterator():
+"""Yields from/to lines of text with a change indication.
+This function is an iterator.  It itself pulls lines from a
+differencing iterator, processes them and yields them.  When it can
+it yields both a "from" and a "to" line, otherwise it will yield one
+or the other.  In addition to yielding the lines of from/to text, a
+boolean flag is yielded to indicate if the text line(s) have
+differences in them.
+Note, this function is purposefully not defined at the module scope so
+that data it needs from its parent function (within whose context it
+is defined) does not need to be of module scope.
+"""
+lines = []
+num_blanks_pending, num_blanks_to_yield = 0, 0
+while True:
+# Load up next 4 lines so we can look ahead, create strings which
+# are a concatenation of the first character of each of the 4 lines
+# so we can do some very readable comparisons.
+while len(lines) < 4:
+try:
+lines.append(diff_lines_iterator.next())
+except StopIteration:
+lines.append('X')
+s = ''.join([line[0] for line in lines])
+if s.startswith('X'):
+# When no more lines, pump out any remaining blank lines so the
+# corresponding add/delete lines get a matching blank line so
+# all line pairs get yielded at the next level.
+num_blanks_to_yield = num_blanks_pending
+elif s.startswith('-?+?'):
+# simple intraline change
+yield _make_line(lines,'?',0), _make_line(lines,'?',1), True
+continue
+elif s.startswith('--++'):
+# in delete block, add block coming: we do NOT want to get
+# caught up on blank lines yet, just process the delete line
+num_blanks_pending -= 1
+yield _make_line(lines,'-',0), None, True
+continue
+elif s.startswith(('--?+', '--+', '- ')):
+# in delete block and see a intraline change or unchanged line
+# coming: yield the delete line and then blanks
+from_line,to_line = _make_line(lines,'-',0), None
+num_blanks_to_yield,num_blanks_pending = num_blanks_pending-1,0
+elif s.startswith('-+?'):
+# intraline change
+yield _make_line(lines,None,0), _make_line(lines,'?',1), True
+continue
+elif s.startswith('-?+'):
+# intraline change
+yield _make_line(lines,'?',0), _make_line(lines,None,1), True
+continue
+elif s.startswith('-'):
+# delete FROM line
+num_blanks_pending -= 1
+yield _make_line(lines,'-',0), None, True
+continue
+elif s.startswith('+--'):
+# in add block, delete block coming: we do NOT want to get
+# caught up on blank lines yet, just process the add line
+num_blanks_pending += 1
+yield None, _make_line(lines,'+',1), True
+continue
+elif s.startswith(('+ ', '+-')):
+# will be leaving an add block: yield blanks then add line
+from_line, to_line = None, _make_line(lines,'+',1)
+num_blanks_to_yield,num_blanks_pending = num_blanks_pending+1,0
+elif s.startswith('+'):
+# inside an add block, yield the add line
+num_blanks_pending += 1
+yield None, _make_line(lines,'+',1), True
+continue
+elif s.startswith(' '):
+# unchanged text, yield it to both sides
+yield _make_line(lines[:],None,0),_make_line(lines,None,1),False
+continue
+# Catch up on the blank lines so when we yield the next from/to
+# pair, they are lined up.
+while(num_blanks_to_yield < 0):
+num_blanks_to_yield += 1
+yield None,('','\n'),True
+while(num_blanks_to_yield > 0):
+num_blanks_to_yield -= 1
+yield ('','\n'),None,True
+if s.startswith('X'):
+raise StopIteration
+else:
+yield from_line,to_line,True
+def _line_pair_iterator():
+"""Yields from/to lines of text with a change indication.
+This function is an iterator.  It itself pulls lines from the line
+iterator.  Its difference from that iterator is that this function
+always yields a pair of from/to text lines (with the change
+indication).  If necessary it will collect single from/to lines
+until it has a matching pair from/to pair to yield.
+Note, this function is purposefully not defined at the module scope so
+that data it needs from its parent function (within whose context it
+is defined) does not need to be of module scope.
+"""
+line_iterator = _line_iterator()
+fromlines,tolines=[],[]
+while True:
+# Collecting lines of text until we have a from/to pair
+while (len(fromlines)==0 or len(tolines)==0):
+from_line, to_line, found_diff =line_iterator.next()
+if from_line is not None:
+fromlines.append((from_line,found_diff))
+if to_line is not None:
+tolines.append((to_line,found_diff))
+# Once we have a pair, remove them from the collection and yield it
+from_line, fromDiff = fromlines.pop(0)
+to_line, to_diff = tolines.pop(0)
+yield (from_line,to_line,fromDiff or to_diff)
+# Handle case where user does not want context differencing, just yield
+# them up without doing anything else with them.
+line_pair_iterator = _line_pair_iterator()
+if context is None:
+while True:
+yield line_pair_iterator.next()
+# Handle case where user wants context differencing.  We must do some
+# storage of lines until we know for sure that they are to be yielded.
+else:
+context += 1
+lines_to_write = 0
+while True:
+# Store lines up until we find a difference, note use of a
+# circular queue because we only need to keep around what
+# we need for context.
+index, contextLines = 0, [None]*(context)
+found_diff = False
+while(found_diff is False):
+from_line, to_line, found_diff = line_pair_iterator.next()
+i = index % context
+contextLines[i] = (from_line, to_line, found_diff)
+index += 1
+# Yield lines that we have collected so far, but first yield
+# the user's separator.
+if index > context:
+yield None, None, None
+lines_to_write = context
+else:
+lines_to_write = index
+index = 0
+while(lines_to_write):
+i = index % context
+index += 1
+yield contextLines[i]
+lines_to_write -= 1
+# Now yield the context lines after the change
+lines_to_write = context-1
+while(lines_to_write):
+from_line, to_line, found_diff = line_pair_iterator.next()
+# If another change within the context, extend the context
+if found_diff:
+lines_to_write = context-1
+else:
+lines_to_write -= 1
+yield from_line, to_line, found_diff
+_file_template = """
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
+"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html>
+<head>
+<meta http-equiv="Content-Type"
+content="text/html; charset=ISO-8859-1" />
+<title></title>
+<style type="text/css">%(styles)s
+</style>
+</head>
+<body>
+%(table)s%(legend)s
+</body>
+</html>"""
+_styles = """
+table.diff {font-family:Courier; border:medium;}
+.diff_header {background-color:#e0e0e0}
+td.diff_header {text-align:right}
+.diff_next {background-color:#c0c0c0}
+.diff_add {background-color:#aaffaa}
+.diff_chg {background-color:#ffff77}
+.diff_sub {background-color:#ffaaaa}"""
+_table_template = """
+<table class="diff" id="difflib_chg_%(prefix)s_top"
+cellspacing="0" cellpadding="0" rules="groups" >
+<colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
+<colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
+%(header_row)s
+<tbody>
+%(data_rows)s        </tbody>
+</table>"""
+_legend = """
+<table class="diff" summary="Legends">
+<tr> <th colspan="2"> Legends </th> </tr>
+<tr> <td> <table border="" summary="Colors">
+<tr><th> Colors </th> </tr>
+<tr><td class="diff_add">&nbsp;Added&nbsp;</td></tr>
+<tr><td class="diff_chg">Changed</td> </tr>
+<tr><td class="diff_sub">Deleted</td> </tr>
+</table></td>
+<td> <table border="" summary="Links">
+<tr><th colspan="2"> Links </th> </tr>
+<tr><td>(f)irst change</td> </tr>
+<tr><td>(n)ext change</td> </tr>
+<tr><td>(t)op</td> </tr>
+</table></td> </tr>
+</table>"""
+class HtmlDiff(object):
+"""For producing HTML side by side comparison with change highlights.
+This class can be used to create an HTML table (or a complete HTML file
+containing the table) showing a side by side, line by line comparison
+of text with inter-line and intra-line change highlights.  The table can
+be generated in either full or contextual difference mode.
+The following methods are provided for HTML generation:
+make_table -- generates HTML for a single side by side table
+make_file -- generates complete HTML file with a single side by side table
+See tools/scripts/diff.py for an example usage of this class.
+"""
+_file_template = _file_template
+_styles = _styles
+_table_template = _table_template
+_legend = _legend
+_default_prefix = 0
+def __init__(self,tabsize=8,wrapcolumn=None,linejunk=None,
+charjunk=IS_CHARACTER_JUNK):
+"""HtmlDiff instance initializer
+Arguments:
+tabsize -- tab stop spacing, defaults to 8.
+wrapcolumn -- column number where lines are broken and wrapped,
+defaults to None where lines are not wrapped.
+linejunk,charjunk -- keyword arguments passed into ndiff() (used to by
+HtmlDiff() to generate the side by side HTML differences).  See
+ndiff() documentation for argument default values and descriptions.
+"""
+self._tabsize = tabsize
+self._wrapcolumn = wrapcolumn
+self._linejunk = linejunk
+self._charjunk = charjunk
+def make_file(self,fromlines,tolines,fromdesc='',todesc='',context=False,
+numlines=5):
+"""Returns HTML file of side by side comparison with change highlights
+Arguments:
+fromlines -- list of "from" lines
+tolines -- list of "to" lines
+fromdesc -- "from" file column header string
+todesc -- "to" file column header string
+context -- set to True for contextual differences (defaults to False
+which shows full differences).
+numlines -- number of context lines.  When context is set True,
+controls number of lines displayed before and after the change.
+When context is False, controls the number of lines to place
+the "next" link anchors before the next change (so click of
+"next" link jumps to just before the change).
+"""
+return self._file_template % dict(
+styles = self._styles,
+legend = self._legend,
+table = self.make_table(fromlines,tolines,fromdesc,todesc,
+context=context,numlines=numlines))
+def _tab_newline_replace(self,fromlines,tolines):
+"""Returns from/to line lists with tabs expanded and newlines removed.
+Instead of tab characters being replaced by the number of spaces
+needed to fill in to the next tab stop, this function will fill
+the space with tab characters.  This is done so that the difference
+algorithms can identify changes in a file when tabs are replaced by
+spaces and vice versa.  At the end of the HTML generation, the tab
+characters will be replaced with a nonbreakable space.
+"""
+def expand_tabs(line):
+# hide real spaces
+line = line.replace(' ','\0')
+# expand tabs into spaces
+line = line.expandtabs(self._tabsize)
+# relace spaces from expanded tabs back into tab characters
+# (we'll replace them with markup after we do differencing)
+line = line.replace(' ','\t')
+return line.replace('\0',' ').rstrip('\n')
+fromlines = [expand_tabs(line) for line in fromlines]
+tolines = [expand_tabs(line) for line in tolines]
+return fromlines,tolines
+def _split_line(self,data_list,line_num,text):
+"""Builds list of text lines by splitting text lines at wrap point
+This function will determine if the input text line needs to be
+wrapped (split) into separate lines.  If so, the first wrap point
+will be determined and the first line appended to the output
+text line list.  This function is used recursively to handle
+the second part of the split line to further split it.
+"""
+# if blank line or context separator, just add it to the output list
+if not line_num:
+data_list.append((line_num,text))
+return
+# if line text doesn't need wrapping, just add it to the output list
+size = len(text)
+max = self._wrapcolumn
+if (size <= max) or ((size -(text.count('\0')*3)) <= max):
+data_list.append((line_num,text))
+return
+# scan text looking for the wrap point, keeping track if the wrap
+# point is inside markers
+i = 0
+n = 0
+mark = ''
+while n < max and i < size:
+if text[i] == '\0':
+i += 1
+mark = text[i]
+i += 1
+elif text[i] == '\1':
+i += 1
+mark = ''
+else:
+i += 1
+n += 1
+# wrap point is inside text, break it up into separate lines
+line1 = text[:i]
+line2 = text[i:]
+# if wrap point is inside markers, place end marker at end of first
+# line and start marker at beginning of second line because each
+# line will have its own table tag markup around it.
+if mark:
+line1 = line1 + '\1'
+line2 = '\0' + mark + line2
+# tack on first line onto the output list
+data_list.append((line_num,line1))
+# use this routine again to wrap the remaining text
+self._split_line(data_list,'>',line2)
+def _line_wrapper(self,diffs):
+"""Returns iterator that splits (wraps) mdiff text lines"""
+# pull from/to data and flags from mdiff iterator
+for fromdata,todata,flag in diffs:
+# check for context separators and pass them through
+if flag is None:
+yield fromdata,todata,flag
+continue
+(fromline,fromtext),(toline,totext) = fromdata,todata
+# for each from/to line split it at the wrap column to form
+# list of text lines.
+fromlist,tolist = [],[]
+self._split_line(fromlist,fromline,fromtext)
+self._split_line(tolist,toline,totext)
+# yield from/to line in pairs inserting blank lines as
+# necessary when one side has more wrapped lines
+while fromlist or tolist:
+if fromlist:
+fromdata = fromlist.pop(0)
+else:
+fromdata = ('',' ')
+if tolist:
+todata = tolist.pop(0)
+else:
+todata = ('',' ')
+yield fromdata,todata,flag
+def _collect_lines(self,diffs):
+"""Collects mdiff output into separate lists
+Before storing the mdiff from/to data into a list, it is converted
+into a single line of text with HTML markup.
+"""
+fromlist,tolist,flaglist = [],[],[]
+# pull from/to data and flags from mdiff style iterator
+for fromdata,todata,flag in diffs:
+try:
+# store HTML markup of the lines into the lists
+fromlist.append(self._format_line(0,flag,*fromdata))
+tolist.append(self._format_line(1,flag,*todata))
+except TypeError:
+# exceptions occur for lines where context separators go
+fromlist.append(None)
+tolist.append(None)
+flaglist.append(flag)
+return fromlist,tolist,flaglist
+def _format_line(self,side,flag,linenum,text):
+"""Returns HTML markup of "from" / "to" text lines
+side -- 0 or 1 indicating "from" or "to" text
+flag -- indicates if difference on line
+linenum -- line number (used for line number column)
+text -- line text to be marked up
+"""
+try:
+linenum = '%d' % linenum
+id = ' id="%s%s"' % (self._prefix[side],linenum)
+except TypeError:
+# handle blank lines where linenum is '>' or ''
+id = ''
+# replace those things that would get confused with HTML symbols
+text=text.replace("&","&amp;").replace(">","&gt;").replace("<","&lt;")
+# make space non-breakable so they don't get compressed or line wrapped
+text = text.replace(' ','&nbsp;').rstrip()
+return '<td class="diff_header"%s>%s</td><td nowrap="nowrap">%s</td>' \
+% (id,linenum,text)
+def _make_prefix(self):
+"""Create unique anchor prefixes"""
+# Generate a unique anchor prefix so multiple tables
+# can exist on the same HTML page without conflicts.
+fromprefix = "from%d_" % HtmlDiff._default_prefix
+toprefix = "to%d_" % HtmlDiff._default_prefix
+HtmlDiff._default_prefix += 1
+# store prefixes so line format method has access
+self._prefix = [fromprefix,toprefix]
+def _convert_flags(self,fromlist,tolist,flaglist,context,numlines):
+"""Makes list of "next" links"""
+# all anchor names will be generated using the unique "to" prefix
+toprefix = self._prefix[1]
+# process change flags, generating middle column of next anchors/links
+next_id = ['']*len(flaglist)
+next_href = ['']*len(flaglist)
+num_chg, in_change = 0, False
+last = 0
+for i,flag in enumerate(flaglist):
+if flag:
+if not in_change:
+in_change = True
+last = i
+# at the beginning of a change, drop an anchor a few lines
+# (the context lines) before the change for the previous
+# link
+i = max([0,i-numlines])
+next_id[i] = ' id="difflib_chg_%s_%d"' % (toprefix,num_chg)
+# at the beginning of a change, drop a link to the next
+# change
+num_chg += 1
+next_href[last] = '<a href="#difflib_chg_%s_%d">n</a>' % (
+toprefix,num_chg)
+else:
+in_change = False
+# check for cases where there is no content to avoid exceptions
+if not flaglist:
+flaglist = [False]
+next_id = ['']
+next_href = ['']
+last = 0
+if context:
+fromlist = ['<td></td><td>&nbsp;No Differences Found&nbsp;</td>']
+tolist = fromlist
+else:
+fromlist = tolist = ['<td></td><td>&nbsp;Empty File&nbsp;</td>']
+# if not a change on first line, drop a link
+if not flaglist[0]:
+next_href[0] = '<a href="#difflib_chg_%s_0">f</a>' % toprefix
+# redo the last link to link to the top
+next_href[last] = '<a href="#difflib_chg_%s_top">t</a>' % (toprefix)
+return fromlist,tolist,flaglist,next_href,next_id
+def make_table(self,fromlines,tolines,fromdesc='',todesc='',context=False,
+numlines=5):
+"""Returns HTML table of side by side comparison with change highlights
+Arguments:
+fromlines -- list of "from" lines
+tolines -- list of "to" lines
+fromdesc -- "from" file column header string
+todesc -- "to" file column header string
+context -- set to True for contextual differences (defaults to False
+which shows full differences).
+numlines -- number of context lines.  When context is set True,
+controls number of lines displayed before and after the change.
+When context is False, controls the number of lines to place
+the "next" link anchors before the next change (so click of
+"next" link jumps to just before the change).
+"""
+# make unique anchor prefixes so that multiple tables may exist
+# on the same page without conflict.
+self._make_prefix()
+# change tabs to spaces before it gets more difficult after we insert
+# markkup
+fromlines,tolines = self._tab_newline_replace(fromlines,tolines)
+# create diffs iterator which generates side by side from/to data
+if context:
+context_lines = numlines
+else:
+context_lines = None
+diffs = _mdiff(fromlines,tolines,context_lines,linejunk=self._linejunk,
+charjunk=self._charjunk)
+# set up iterator to wrap lines that exceed desired width
+if self._wrapcolumn:
+diffs = self._line_wrapper(diffs)
+# collect up from/to lines and flags into lists (also format the lines)
+fromlist,tolist,flaglist = self._collect_lines(diffs)
+# process change flags, generating middle column of next anchors/links
+fromlist,tolist,flaglist,next_href,next_id = self._convert_flags(
+fromlist,tolist,flaglist,context,numlines)
+s = []
+fmt = '            <tr><td class="diff_next"%s>%s</td>%s' + \
+'<td class="diff_next">%s</td>%s</tr>\n'
+for i in range(len(flaglist)):
+if flaglist[i] is None:
+# mdiff yields None on separator lines skip the bogus ones
+# generated for the first line
+if i > 0:
+s.append('        </tbody>        \n        <tbody>\n')
+else:
+s.append( fmt % (next_id[i],next_href[i],fromlist[i],
+next_href[i],tolist[i]))
+if fromdesc or todesc:
+header_row = '<thead><tr>%s%s%s%s</tr></thead>' % (
+'<th class="diff_next"><br /></th>',
+'<th colspan="2" class="diff_header">%s</th>' % fromdesc,
+'<th class="diff_next"><br /></th>',
+'<th colspan="2" class="diff_header">%s</th>' % todesc)
+else:
+header_row = ''
+table = self._table_template % dict(
+data_rows=''.join(s),
+header_row=header_row,
+prefix=self._prefix[1])
+return table.replace('\0+','<span class="diff_add">'). \
+replace('\0-','<span class="diff_sub">'). \
+replace('\0^','<span class="diff_chg">'). \
+replace('\1','</span>'). \
+replace('\t','&nbsp;')
+del re
+def restore(delta, which):
+r"""
+Generate one of the two sequences that generated a delta.
+Given a `delta` produced by `Differ.compare()` or `ndiff()`, extract
+lines originating from file 1 or 2 (parameter `which`), stripping off line
+prefixes.
+Examples:
+>>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1),
+...              'ore\ntree\nemu\n'.splitlines(1))
+>>> diff = list(diff)
+>>> print ''.join(restore(diff, 1)),
+one
+two
+three
+>>> print ''.join(restore(diff, 2)),
+ore
+tree
+emu
+"""
+try:
+tag = {1: "- ", 2: "+ "}[int(which)]
+except KeyError:
+raise ValueError, ('unknown delta choice (must be 1 or 2): %r'
+% which)
+prefixes = ("  ", tag)
+for line in delta:
+if line[:2] in prefixes:
+yield line[2:]
+def _test():
+import doctest, difflib
+return doctest.testmod(difflib)
+if __name__ == "__main__":
+_test()