Coverage for /pythoncovmergedfiles/medio/medio/usr/lib/python3.9/difflib.py: 10%
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1"""
2Module difflib -- helpers for computing deltas between objects.
4Function get_close_matches(word, possibilities, n=3, cutoff=0.6):
5 Use SequenceMatcher to return list of the best "good enough" matches.
7Function context_diff(a, b):
8 For two lists of strings, return a delta in context diff format.
10Function ndiff(a, b):
11 Return a delta: the difference between `a` and `b` (lists of strings).
13Function restore(delta, which):
14 Return one of the two sequences that generated an ndiff delta.
16Function unified_diff(a, b):
17 For two lists of strings, return a delta in unified diff format.
19Class SequenceMatcher:
20 A flexible class for comparing pairs of sequences of any type.
22Class Differ:
23 For producing human-readable deltas from sequences of lines of text.
25Class HtmlDiff:
26 For producing HTML side by side comparison with change highlights.
27"""
29__all__ = ['get_close_matches', 'ndiff', 'restore', 'SequenceMatcher',
30 'Differ','IS_CHARACTER_JUNK', 'IS_LINE_JUNK', 'context_diff',
31 'unified_diff', 'diff_bytes', 'HtmlDiff', 'Match']
33from heapq import nlargest as _nlargest
34from collections import namedtuple as _namedtuple
35from types import GenericAlias
37Match = _namedtuple('Match', 'a b size')
39def _calculate_ratio(matches, length):
40 if length:
41 return 2.0 * matches / length
42 return 1.0
44class SequenceMatcher:
46 """
47 SequenceMatcher is a flexible class for comparing pairs of sequences of
48 any type, so long as the sequence elements are hashable. The basic
49 algorithm predates, and is a little fancier than, an algorithm
50 published in the late 1980's by Ratcliff and Obershelp under the
51 hyperbolic name "gestalt pattern matching". The basic idea is to find
52 the longest contiguous matching subsequence that contains no "junk"
53 elements (R-O doesn't address junk). The same idea is then applied
54 recursively to the pieces of the sequences to the left and to the right
55 of the matching subsequence. This does not yield minimal edit
56 sequences, but does tend to yield matches that "look right" to people.
58 SequenceMatcher tries to compute a "human-friendly diff" between two
59 sequences. Unlike e.g. UNIX(tm) diff, the fundamental notion is the
60 longest *contiguous* & junk-free matching subsequence. That's what
61 catches peoples' eyes. The Windows(tm) windiff has another interesting
62 notion, pairing up elements that appear uniquely in each sequence.
63 That, and the method here, appear to yield more intuitive difference
64 reports than does diff. This method appears to be the least vulnerable
65 to synching up on blocks of "junk lines", though (like blank lines in
66 ordinary text files, or maybe "<P>" lines in HTML files). That may be
67 because this is the only method of the 3 that has a *concept* of
68 "junk" <wink>.
70 Example, comparing two strings, and considering blanks to be "junk":
72 >>> s = SequenceMatcher(lambda x: x == " ",
73 ... "private Thread currentThread;",
74 ... "private volatile Thread currentThread;")
75 >>>
77 .ratio() returns a float in [0, 1], measuring the "similarity" of the
78 sequences. As a rule of thumb, a .ratio() value over 0.6 means the
79 sequences are close matches:
81 >>> print(round(s.ratio(), 3))
82 0.866
83 >>>
85 If you're only interested in where the sequences match,
86 .get_matching_blocks() is handy:
88 >>> for block in s.get_matching_blocks():
89 ... print("a[%d] and b[%d] match for %d elements" % block)
90 a[0] and b[0] match for 8 elements
91 a[8] and b[17] match for 21 elements
92 a[29] and b[38] match for 0 elements
94 Note that the last tuple returned by .get_matching_blocks() is always a
95 dummy, (len(a), len(b), 0), and this is the only case in which the last
96 tuple element (number of elements matched) is 0.
98 If you want to know how to change the first sequence into the second,
99 use .get_opcodes():
101 >>> for opcode in s.get_opcodes():
102 ... print("%6s a[%d:%d] b[%d:%d]" % opcode)
103 equal a[0:8] b[0:8]
104 insert a[8:8] b[8:17]
105 equal a[8:29] b[17:38]
107 See the Differ class for a fancy human-friendly file differencer, which
108 uses SequenceMatcher both to compare sequences of lines, and to compare
109 sequences of characters within similar (near-matching) lines.
111 See also function get_close_matches() in this module, which shows how
112 simple code building on SequenceMatcher can be used to do useful work.
114 Timing: Basic R-O is cubic time worst case and quadratic time expected
115 case. SequenceMatcher is quadratic time for the worst case and has
116 expected-case behavior dependent in a complicated way on how many
117 elements the sequences have in common; best case time is linear.
119 Methods:
121 __init__(isjunk=None, a='', b='')
122 Construct a SequenceMatcher.
124 set_seqs(a, b)
125 Set the two sequences to be compared.
127 set_seq1(a)
128 Set the first sequence to be compared.
130 set_seq2(b)
131 Set the second sequence to be compared.
133 find_longest_match(alo=0, ahi=None, blo=0, bhi=None)
134 Find longest matching block in a[alo:ahi] and b[blo:bhi].
136 get_matching_blocks()
137 Return list of triples describing matching subsequences.
139 get_opcodes()
140 Return list of 5-tuples describing how to turn a into b.
142 ratio()
143 Return a measure of the sequences' similarity (float in [0,1]).
145 quick_ratio()
146 Return an upper bound on .ratio() relatively quickly.
148 real_quick_ratio()
149 Return an upper bound on ratio() very quickly.
150 """
152 def __init__(self, isjunk=None, a='', b='', autojunk=True):
153 """Construct a SequenceMatcher.
155 Optional arg isjunk is None (the default), or a one-argument
156 function that takes a sequence element and returns true iff the
157 element is junk. None is equivalent to passing "lambda x: 0", i.e.
158 no elements are considered to be junk. For example, pass
159 lambda x: x in " \\t"
160 if you're comparing lines as sequences of characters, and don't
161 want to synch up on blanks or hard tabs.
163 Optional arg a is the first of two sequences to be compared. By
164 default, an empty string. The elements of a must be hashable. See
165 also .set_seqs() and .set_seq1().
167 Optional arg b is the second of two sequences to be compared. By
168 default, an empty string. The elements of b must be hashable. See
169 also .set_seqs() and .set_seq2().
171 Optional arg autojunk should be set to False to disable the
172 "automatic junk heuristic" that treats popular elements as junk
173 (see module documentation for more information).
174 """
176 # Members:
177 # a
178 # first sequence
179 # b
180 # second sequence; differences are computed as "what do
181 # we need to do to 'a' to change it into 'b'?"
182 # b2j
183 # for x in b, b2j[x] is a list of the indices (into b)
184 # at which x appears; junk and popular elements do not appear
185 # fullbcount
186 # for x in b, fullbcount[x] == the number of times x
187 # appears in b; only materialized if really needed (used
188 # only for computing quick_ratio())
189 # matching_blocks
190 # a list of (i, j, k) triples, where a[i:i+k] == b[j:j+k];
191 # ascending & non-overlapping in i and in j; terminated by
192 # a dummy (len(a), len(b), 0) sentinel
193 # opcodes
194 # a list of (tag, i1, i2, j1, j2) tuples, where tag is
195 # one of
196 # 'replace' a[i1:i2] should be replaced by b[j1:j2]
197 # 'delete' a[i1:i2] should be deleted
198 # 'insert' b[j1:j2] should be inserted
199 # 'equal' a[i1:i2] == b[j1:j2]
200 # isjunk
201 # a user-supplied function taking a sequence element and
202 # returning true iff the element is "junk" -- this has
203 # subtle but helpful effects on the algorithm, which I'll
204 # get around to writing up someday <0.9 wink>.
205 # DON'T USE! Only __chain_b uses this. Use "in self.bjunk".
206 # bjunk
207 # the items in b for which isjunk is True.
208 # bpopular
209 # nonjunk items in b treated as junk by the heuristic (if used).
211 self.isjunk = isjunk
212 self.a = self.b = None
213 self.autojunk = autojunk
214 self.set_seqs(a, b)
216 def set_seqs(self, a, b):
217 """Set the two sequences to be compared.
219 >>> s = SequenceMatcher()
220 >>> s.set_seqs("abcd", "bcde")
221 >>> s.ratio()
222 0.75
223 """
225 self.set_seq1(a)
226 self.set_seq2(b)
228 def set_seq1(self, a):
229 """Set the first sequence to be compared.
231 The second sequence to be compared is not changed.
233 >>> s = SequenceMatcher(None, "abcd", "bcde")
234 >>> s.ratio()
235 0.75
236 >>> s.set_seq1("bcde")
237 >>> s.ratio()
238 1.0
239 >>>
241 SequenceMatcher computes and caches detailed information about the
242 second sequence, so if you want to compare one sequence S against
243 many sequences, use .set_seq2(S) once and call .set_seq1(x)
244 repeatedly for each of the other sequences.
246 See also set_seqs() and set_seq2().
247 """
249 if a is self.a:
250 return
251 self.a = a
252 self.matching_blocks = self.opcodes = None
254 def set_seq2(self, b):
255 """Set the second sequence to be compared.
257 The first sequence to be compared is not changed.
259 >>> s = SequenceMatcher(None, "abcd", "bcde")
260 >>> s.ratio()
261 0.75
262 >>> s.set_seq2("abcd")
263 >>> s.ratio()
264 1.0
265 >>>
267 SequenceMatcher computes and caches detailed information about the
268 second sequence, so if you want to compare one sequence S against
269 many sequences, use .set_seq2(S) once and call .set_seq1(x)
270 repeatedly for each of the other sequences.
272 See also set_seqs() and set_seq1().
273 """
275 if b is self.b:
276 return
277 self.b = b
278 self.matching_blocks = self.opcodes = None
279 self.fullbcount = None
280 self.__chain_b()
282 # For each element x in b, set b2j[x] to a list of the indices in
283 # b where x appears; the indices are in increasing order; note that
284 # the number of times x appears in b is len(b2j[x]) ...
285 # when self.isjunk is defined, junk elements don't show up in this
286 # map at all, which stops the central find_longest_match method
287 # from starting any matching block at a junk element ...
288 # b2j also does not contain entries for "popular" elements, meaning
289 # elements that account for more than 1 + 1% of the total elements, and
290 # when the sequence is reasonably large (>= 200 elements); this can
291 # be viewed as an adaptive notion of semi-junk, and yields an enormous
292 # speedup when, e.g., comparing program files with hundreds of
293 # instances of "return NULL;" ...
294 # note that this is only called when b changes; so for cross-product
295 # kinds of matches, it's best to call set_seq2 once, then set_seq1
296 # repeatedly
298 def __chain_b(self):
299 # Because isjunk is a user-defined (not C) function, and we test
300 # for junk a LOT, it's important to minimize the number of calls.
301 # Before the tricks described here, __chain_b was by far the most
302 # time-consuming routine in the whole module! If anyone sees
303 # Jim Roskind, thank him again for profile.py -- I never would
304 # have guessed that.
305 # The first trick is to build b2j ignoring the possibility
306 # of junk. I.e., we don't call isjunk at all yet. Throwing
307 # out the junk later is much cheaper than building b2j "right"
308 # from the start.
309 b = self.b
310 self.b2j = b2j = {}
312 for i, elt in enumerate(b):
313 indices = b2j.setdefault(elt, [])
314 indices.append(i)
316 # Purge junk elements
317 self.bjunk = junk = set()
318 isjunk = self.isjunk
319 if isjunk:
320 for elt in b2j.keys():
321 if isjunk(elt):
322 junk.add(elt)
323 for elt in junk: # separate loop avoids separate list of keys
324 del b2j[elt]
326 # Purge popular elements that are not junk
327 self.bpopular = popular = set()
328 n = len(b)
329 if self.autojunk and n >= 200:
330 ntest = n // 100 + 1
331 for elt, idxs in b2j.items():
332 if len(idxs) > ntest:
333 popular.add(elt)
334 for elt in popular: # ditto; as fast for 1% deletion
335 del b2j[elt]
337 def find_longest_match(self, alo=0, ahi=None, blo=0, bhi=None):
338 """Find longest matching block in a[alo:ahi] and b[blo:bhi].
340 By default it will find the longest match in the entirety of a and b.
342 If isjunk is not defined:
344 Return (i,j,k) such that a[i:i+k] is equal to b[j:j+k], where
345 alo <= i <= i+k <= ahi
346 blo <= j <= j+k <= bhi
347 and for all (i',j',k') meeting those conditions,
348 k >= k'
349 i <= i'
350 and if i == i', j <= j'
352 In other words, of all maximal matching blocks, return one that
353 starts earliest in a, and of all those maximal matching blocks that
354 start earliest in a, return the one that starts earliest in b.
356 >>> s = SequenceMatcher(None, " abcd", "abcd abcd")
357 >>> s.find_longest_match(0, 5, 0, 9)
358 Match(a=0, b=4, size=5)
360 If isjunk is defined, first the longest matching block is
361 determined as above, but with the additional restriction that no
362 junk element appears in the block. Then that block is extended as
363 far as possible by matching (only) junk elements on both sides. So
364 the resulting block never matches on junk except as identical junk
365 happens to be adjacent to an "interesting" match.
367 Here's the same example as before, but considering blanks to be
368 junk. That prevents " abcd" from matching the " abcd" at the tail
369 end of the second sequence directly. Instead only the "abcd" can
370 match, and matches the leftmost "abcd" in the second sequence:
372 >>> s = SequenceMatcher(lambda x: x==" ", " abcd", "abcd abcd")
373 >>> s.find_longest_match(0, 5, 0, 9)
374 Match(a=1, b=0, size=4)
376 If no blocks match, return (alo, blo, 0).
378 >>> s = SequenceMatcher(None, "ab", "c")
379 >>> s.find_longest_match(0, 2, 0, 1)
380 Match(a=0, b=0, size=0)
381 """
383 # CAUTION: stripping common prefix or suffix would be incorrect.
384 # E.g.,
385 # ab
386 # acab
387 # Longest matching block is "ab", but if common prefix is
388 # stripped, it's "a" (tied with "b"). UNIX(tm) diff does so
389 # strip, so ends up claiming that ab is changed to acab by
390 # inserting "ca" in the middle. That's minimal but unintuitive:
391 # "it's obvious" that someone inserted "ac" at the front.
392 # Windiff ends up at the same place as diff, but by pairing up
393 # the unique 'b's and then matching the first two 'a's.
395 a, b, b2j, isbjunk = self.a, self.b, self.b2j, self.bjunk.__contains__
396 if ahi is None:
397 ahi = len(a)
398 if bhi is None:
399 bhi = len(b)
400 besti, bestj, bestsize = alo, blo, 0
401 # find longest junk-free match
402 # during an iteration of the loop, j2len[j] = length of longest
403 # junk-free match ending with a[i-1] and b[j]
404 j2len = {}
405 nothing = []
406 for i in range(alo, ahi):
407 # look at all instances of a[i] in b; note that because
408 # b2j has no junk keys, the loop is skipped if a[i] is junk
409 j2lenget = j2len.get
410 newj2len = {}
411 for j in b2j.get(a[i], nothing):
412 # a[i] matches b[j]
413 if j < blo:
414 continue
415 if j >= bhi:
416 break
417 k = newj2len[j] = j2lenget(j-1, 0) + 1
418 if k > bestsize:
419 besti, bestj, bestsize = i-k+1, j-k+1, k
420 j2len = newj2len
422 # Extend the best by non-junk elements on each end. In particular,
423 # "popular" non-junk elements aren't in b2j, which greatly speeds
424 # the inner loop above, but also means "the best" match so far
425 # doesn't contain any junk *or* popular non-junk elements.
426 while besti > alo and bestj > blo and \
427 not isbjunk(b[bestj-1]) and \
428 a[besti-1] == b[bestj-1]:
429 besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
430 while besti+bestsize < ahi and bestj+bestsize < bhi and \
431 not isbjunk(b[bestj+bestsize]) and \
432 a[besti+bestsize] == b[bestj+bestsize]:
433 bestsize += 1
435 # Now that we have a wholly interesting match (albeit possibly
436 # empty!), we may as well suck up the matching junk on each
437 # side of it too. Can't think of a good reason not to, and it
438 # saves post-processing the (possibly considerable) expense of
439 # figuring out what to do with it. In the case of an empty
440 # interesting match, this is clearly the right thing to do,
441 # because no other kind of match is possible in the regions.
442 while besti > alo and bestj > blo and \
443 isbjunk(b[bestj-1]) and \
444 a[besti-1] == b[bestj-1]:
445 besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
446 while besti+bestsize < ahi and bestj+bestsize < bhi and \
447 isbjunk(b[bestj+bestsize]) and \
448 a[besti+bestsize] == b[bestj+bestsize]:
449 bestsize = bestsize + 1
451 return Match(besti, bestj, bestsize)
453 def get_matching_blocks(self):
454 """Return list of triples describing matching subsequences.
456 Each triple is of the form (i, j, n), and means that
457 a[i:i+n] == b[j:j+n]. The triples are monotonically increasing in
458 i and in j. New in Python 2.5, it's also guaranteed that if
459 (i, j, n) and (i', j', n') are adjacent triples in the list, and
460 the second is not the last triple in the list, then i+n != i' or
461 j+n != j'. IOW, adjacent triples never describe adjacent equal
462 blocks.
464 The last triple is a dummy, (len(a), len(b), 0), and is the only
465 triple with n==0.
467 >>> s = SequenceMatcher(None, "abxcd", "abcd")
468 >>> list(s.get_matching_blocks())
469 [Match(a=0, b=0, size=2), Match(a=3, b=2, size=2), Match(a=5, b=4, size=0)]
470 """
472 if self.matching_blocks is not None:
473 return self.matching_blocks
474 la, lb = len(self.a), len(self.b)
476 # This is most naturally expressed as a recursive algorithm, but
477 # at least one user bumped into extreme use cases that exceeded
478 # the recursion limit on their box. So, now we maintain a list
479 # ('queue`) of blocks we still need to look at, and append partial
480 # results to `matching_blocks` in a loop; the matches are sorted
481 # at the end.
482 queue = [(0, la, 0, lb)]
483 matching_blocks = []
484 while queue:
485 alo, ahi, blo, bhi = queue.pop()
486 i, j, k = x = self.find_longest_match(alo, ahi, blo, bhi)
487 # a[alo:i] vs b[blo:j] unknown
488 # a[i:i+k] same as b[j:j+k]
489 # a[i+k:ahi] vs b[j+k:bhi] unknown
490 if k: # if k is 0, there was no matching block
491 matching_blocks.append(x)
492 if alo < i and blo < j:
493 queue.append((alo, i, blo, j))
494 if i+k < ahi and j+k < bhi:
495 queue.append((i+k, ahi, j+k, bhi))
496 matching_blocks.sort()
498 # It's possible that we have adjacent equal blocks in the
499 # matching_blocks list now. Starting with 2.5, this code was added
500 # to collapse them.
501 i1 = j1 = k1 = 0
502 non_adjacent = []
503 for i2, j2, k2 in matching_blocks:
504 # Is this block adjacent to i1, j1, k1?
505 if i1 + k1 == i2 and j1 + k1 == j2:
506 # Yes, so collapse them -- this just increases the length of
507 # the first block by the length of the second, and the first
508 # block so lengthened remains the block to compare against.
509 k1 += k2
510 else:
511 # Not adjacent. Remember the first block (k1==0 means it's
512 # the dummy we started with), and make the second block the
513 # new block to compare against.
514 if k1:
515 non_adjacent.append((i1, j1, k1))
516 i1, j1, k1 = i2, j2, k2
517 if k1:
518 non_adjacent.append((i1, j1, k1))
520 non_adjacent.append( (la, lb, 0) )
521 self.matching_blocks = list(map(Match._make, non_adjacent))
522 return self.matching_blocks
524 def get_opcodes(self):
525 """Return list of 5-tuples describing how to turn a into b.
527 Each tuple is of the form (tag, i1, i2, j1, j2). The first tuple
528 has i1 == j1 == 0, and remaining tuples have i1 == the i2 from the
529 tuple preceding it, and likewise for j1 == the previous j2.
531 The tags are strings, with these meanings:
533 'replace': a[i1:i2] should be replaced by b[j1:j2]
534 'delete': a[i1:i2] should be deleted.
535 Note that j1==j2 in this case.
536 'insert': b[j1:j2] should be inserted at a[i1:i1].
537 Note that i1==i2 in this case.
538 'equal': a[i1:i2] == b[j1:j2]
540 >>> a = "qabxcd"
541 >>> b = "abycdf"
542 >>> s = SequenceMatcher(None, a, b)
543 >>> for tag, i1, i2, j1, j2 in s.get_opcodes():
544 ... print(("%7s a[%d:%d] (%s) b[%d:%d] (%s)" %
545 ... (tag, i1, i2, a[i1:i2], j1, j2, b[j1:j2])))
546 delete a[0:1] (q) b[0:0] ()
547 equal a[1:3] (ab) b[0:2] (ab)
548 replace a[3:4] (x) b[2:3] (y)
549 equal a[4:6] (cd) b[3:5] (cd)
550 insert a[6:6] () b[5:6] (f)
551 """
553 if self.opcodes is not None:
554 return self.opcodes
555 i = j = 0
556 self.opcodes = answer = []
557 for ai, bj, size in self.get_matching_blocks():
558 # invariant: we've pumped out correct diffs to change
559 # a[:i] into b[:j], and the next matching block is
560 # a[ai:ai+size] == b[bj:bj+size]. So we need to pump
561 # out a diff to change a[i:ai] into b[j:bj], pump out
562 # the matching block, and move (i,j) beyond the match
563 tag = ''
564 if i < ai and j < bj:
565 tag = 'replace'
566 elif i < ai:
567 tag = 'delete'
568 elif j < bj:
569 tag = 'insert'
570 if tag:
571 answer.append( (tag, i, ai, j, bj) )
572 i, j = ai+size, bj+size
573 # the list of matching blocks is terminated by a
574 # sentinel with size 0
575 if size:
576 answer.append( ('equal', ai, i, bj, j) )
577 return answer
579 def get_grouped_opcodes(self, n=3):
580 """ Isolate change clusters by eliminating ranges with no changes.
582 Return a generator of groups with up to n lines of context.
583 Each group is in the same format as returned by get_opcodes().
585 >>> from pprint import pprint
586 >>> a = list(map(str, range(1,40)))
587 >>> b = a[:]
588 >>> b[8:8] = ['i'] # Make an insertion
589 >>> b[20] += 'x' # Make a replacement
590 >>> b[23:28] = [] # Make a deletion
591 >>> b[30] += 'y' # Make another replacement
592 >>> pprint(list(SequenceMatcher(None,a,b).get_grouped_opcodes()))
593 [[('equal', 5, 8, 5, 8), ('insert', 8, 8, 8, 9), ('equal', 8, 11, 9, 12)],
594 [('equal', 16, 19, 17, 20),
595 ('replace', 19, 20, 20, 21),
596 ('equal', 20, 22, 21, 23),
597 ('delete', 22, 27, 23, 23),
598 ('equal', 27, 30, 23, 26)],
599 [('equal', 31, 34, 27, 30),
600 ('replace', 34, 35, 30, 31),
601 ('equal', 35, 38, 31, 34)]]
602 """
604 codes = self.get_opcodes()
605 if not codes:
606 codes = [("equal", 0, 1, 0, 1)]
607 # Fixup leading and trailing groups if they show no changes.
608 if codes[0][0] == 'equal':
609 tag, i1, i2, j1, j2 = codes[0]
610 codes[0] = tag, max(i1, i2-n), i2, max(j1, j2-n), j2
611 if codes[-1][0] == 'equal':
612 tag, i1, i2, j1, j2 = codes[-1]
613 codes[-1] = tag, i1, min(i2, i1+n), j1, min(j2, j1+n)
615 nn = n + n
616 group = []
617 for tag, i1, i2, j1, j2 in codes:
618 # End the current group and start a new one whenever
619 # there is a large range with no changes.
620 if tag == 'equal' and i2-i1 > nn:
621 group.append((tag, i1, min(i2, i1+n), j1, min(j2, j1+n)))
622 yield group
623 group = []
624 i1, j1 = max(i1, i2-n), max(j1, j2-n)
625 group.append((tag, i1, i2, j1 ,j2))
626 if group and not (len(group)==1 and group[0][0] == 'equal'):
627 yield group
629 def ratio(self):
630 """Return a measure of the sequences' similarity (float in [0,1]).
632 Where T is the total number of elements in both sequences, and
633 M is the number of matches, this is 2.0*M / T.
634 Note that this is 1 if the sequences are identical, and 0 if
635 they have nothing in common.
637 .ratio() is expensive to compute if you haven't already computed
638 .get_matching_blocks() or .get_opcodes(), in which case you may
639 want to try .quick_ratio() or .real_quick_ratio() first to get an
640 upper bound.
642 >>> s = SequenceMatcher(None, "abcd", "bcde")
643 >>> s.ratio()
644 0.75
645 >>> s.quick_ratio()
646 0.75
647 >>> s.real_quick_ratio()
648 1.0
649 """
651 matches = sum(triple[-1] for triple in self.get_matching_blocks())
652 return _calculate_ratio(matches, len(self.a) + len(self.b))
654 def quick_ratio(self):
655 """Return an upper bound on ratio() relatively quickly.
657 This isn't defined beyond that it is an upper bound on .ratio(), and
658 is faster to compute.
659 """
661 # viewing a and b as multisets, set matches to the cardinality
662 # of their intersection; this counts the number of matches
663 # without regard to order, so is clearly an upper bound
664 if self.fullbcount is None:
665 self.fullbcount = fullbcount = {}
666 for elt in self.b:
667 fullbcount[elt] = fullbcount.get(elt, 0) + 1
668 fullbcount = self.fullbcount
669 # avail[x] is the number of times x appears in 'b' less the
670 # number of times we've seen it in 'a' so far ... kinda
671 avail = {}
672 availhas, matches = avail.__contains__, 0
673 for elt in self.a:
674 if availhas(elt):
675 numb = avail[elt]
676 else:
677 numb = fullbcount.get(elt, 0)
678 avail[elt] = numb - 1
679 if numb > 0:
680 matches = matches + 1
681 return _calculate_ratio(matches, len(self.a) + len(self.b))
683 def real_quick_ratio(self):
684 """Return an upper bound on ratio() very quickly.
686 This isn't defined beyond that it is an upper bound on .ratio(), and
687 is faster to compute than either .ratio() or .quick_ratio().
688 """
690 la, lb = len(self.a), len(self.b)
691 # can't have more matches than the number of elements in the
692 # shorter sequence
693 return _calculate_ratio(min(la, lb), la + lb)
695 __class_getitem__ = classmethod(GenericAlias)
698def get_close_matches(word, possibilities, n=3, cutoff=0.6):
699 """Use SequenceMatcher to return list of the best "good enough" matches.
701 word is a sequence for which close matches are desired (typically a
702 string).
704 possibilities is a list of sequences against which to match word
705 (typically a list of strings).
707 Optional arg n (default 3) is the maximum number of close matches to
708 return. n must be > 0.
710 Optional arg cutoff (default 0.6) is a float in [0, 1]. Possibilities
711 that don't score at least that similar to word are ignored.
713 The best (no more than n) matches among the possibilities are returned
714 in a list, sorted by similarity score, most similar first.
716 >>> get_close_matches("appel", ["ape", "apple", "peach", "puppy"])
717 ['apple', 'ape']
718 >>> import keyword as _keyword
719 >>> get_close_matches("wheel", _keyword.kwlist)
720 ['while']
721 >>> get_close_matches("Apple", _keyword.kwlist)
722 []
723 >>> get_close_matches("accept", _keyword.kwlist)
724 ['except']
725 """
727 if not n > 0:
728 raise ValueError("n must be > 0: %r" % (n,))
729 if not 0.0 <= cutoff <= 1.0:
730 raise ValueError("cutoff must be in [0.0, 1.0]: %r" % (cutoff,))
731 result = []
732 s = SequenceMatcher()
733 s.set_seq2(word)
734 for x in possibilities:
735 s.set_seq1(x)
736 if s.real_quick_ratio() >= cutoff and \
737 s.quick_ratio() >= cutoff and \
738 s.ratio() >= cutoff:
739 result.append((s.ratio(), x))
741 # Move the best scorers to head of list
742 result = _nlargest(n, result)
743 # Strip scores for the best n matches
744 return [x for score, x in result]
747def _keep_original_ws(s, tag_s):
748 """Replace whitespace with the original whitespace characters in `s`"""
749 return ''.join(
750 c if tag_c == " " and c.isspace() else tag_c
751 for c, tag_c in zip(s, tag_s)
752 )
756class Differ:
757 r"""
758 Differ is a class for comparing sequences of lines of text, and
759 producing human-readable differences or deltas. Differ uses
760 SequenceMatcher both to compare sequences of lines, and to compare
761 sequences of characters within similar (near-matching) lines.
763 Each line of a Differ delta begins with a two-letter code:
765 '- ' line unique to sequence 1
766 '+ ' line unique to sequence 2
767 ' ' line common to both sequences
768 '? ' line not present in either input sequence
770 Lines beginning with '? ' attempt to guide the eye to intraline
771 differences, and were not present in either input sequence. These lines
772 can be confusing if the sequences contain tab characters.
774 Note that Differ makes no claim to produce a *minimal* diff. To the
775 contrary, minimal diffs are often counter-intuitive, because they synch
776 up anywhere possible, sometimes accidental matches 100 pages apart.
777 Restricting synch points to contiguous matches preserves some notion of
778 locality, at the occasional cost of producing a longer diff.
780 Example: Comparing two texts.
782 First we set up the texts, sequences of individual single-line strings
783 ending with newlines (such sequences can also be obtained from the
784 `readlines()` method of file-like objects):
786 >>> text1 = ''' 1. Beautiful is better than ugly.
787 ... 2. Explicit is better than implicit.
788 ... 3. Simple is better than complex.
789 ... 4. Complex is better than complicated.
790 ... '''.splitlines(keepends=True)
791 >>> len(text1)
792 4
793 >>> text1[0][-1]
794 '\n'
795 >>> text2 = ''' 1. Beautiful is better than ugly.
796 ... 3. Simple is better than complex.
797 ... 4. Complicated is better than complex.
798 ... 5. Flat is better than nested.
799 ... '''.splitlines(keepends=True)
801 Next we instantiate a Differ object:
803 >>> d = Differ()
805 Note that when instantiating a Differ object we may pass functions to
806 filter out line and character 'junk'. See Differ.__init__ for details.
808 Finally, we compare the two:
810 >>> result = list(d.compare(text1, text2))
812 'result' is a list of strings, so let's pretty-print it:
814 >>> from pprint import pprint as _pprint
815 >>> _pprint(result)
816 [' 1. Beautiful is better than ugly.\n',
817 '- 2. Explicit is better than implicit.\n',
818 '- 3. Simple is better than complex.\n',
819 '+ 3. Simple is better than complex.\n',
820 '? ++\n',
821 '- 4. Complex is better than complicated.\n',
822 '? ^ ---- ^\n',
823 '+ 4. Complicated is better than complex.\n',
824 '? ++++ ^ ^\n',
825 '+ 5. Flat is better than nested.\n']
827 As a single multi-line string it looks like this:
829 >>> print(''.join(result), end="")
830 1. Beautiful is better than ugly.
831 - 2. Explicit is better than implicit.
832 - 3. Simple is better than complex.
833 + 3. Simple is better than complex.
834 ? ++
835 - 4. Complex is better than complicated.
836 ? ^ ---- ^
837 + 4. Complicated is better than complex.
838 ? ++++ ^ ^
839 + 5. Flat is better than nested.
841 Methods:
843 __init__(linejunk=None, charjunk=None)
844 Construct a text differencer, with optional filters.
846 compare(a, b)
847 Compare two sequences of lines; generate the resulting delta.
848 """
850 def __init__(self, linejunk=None, charjunk=None):
851 """
852 Construct a text differencer, with optional filters.
854 The two optional keyword parameters are for filter functions:
856 - `linejunk`: A function that should accept a single string argument,
857 and return true iff the string is junk. The module-level function
858 `IS_LINE_JUNK` may be used to filter out lines without visible
859 characters, except for at most one splat ('#'). It is recommended
860 to leave linejunk None; the underlying SequenceMatcher class has
861 an adaptive notion of "noise" lines that's better than any static
862 definition the author has ever been able to craft.
864 - `charjunk`: A function that should accept a string of length 1. The
865 module-level function `IS_CHARACTER_JUNK` may be used to filter out
866 whitespace characters (a blank or tab; **note**: bad idea to include
867 newline in this!). Use of IS_CHARACTER_JUNK is recommended.
868 """
870 self.linejunk = linejunk
871 self.charjunk = charjunk
873 def compare(self, a, b):
874 r"""
875 Compare two sequences of lines; generate the resulting delta.
877 Each sequence must contain individual single-line strings ending with
878 newlines. Such sequences can be obtained from the `readlines()` method
879 of file-like objects. The delta generated also consists of newline-
880 terminated strings, ready to be printed as-is via the writeline()
881 method of a file-like object.
883 Example:
885 >>> print(''.join(Differ().compare('one\ntwo\nthree\n'.splitlines(True),
886 ... 'ore\ntree\nemu\n'.splitlines(True))),
887 ... end="")
888 - one
889 ? ^
890 + ore
891 ? ^
892 - two
893 - three
894 ? -
895 + tree
896 + emu
897 """
899 cruncher = SequenceMatcher(self.linejunk, a, b)
900 for tag, alo, ahi, blo, bhi in cruncher.get_opcodes():
901 if tag == 'replace':
902 g = self._fancy_replace(a, alo, ahi, b, blo, bhi)
903 elif tag == 'delete':
904 g = self._dump('-', a, alo, ahi)
905 elif tag == 'insert':
906 g = self._dump('+', b, blo, bhi)
907 elif tag == 'equal':
908 g = self._dump(' ', a, alo, ahi)
909 else:
910 raise ValueError('unknown tag %r' % (tag,))
912 yield from g
914 def _dump(self, tag, x, lo, hi):
915 """Generate comparison results for a same-tagged range."""
916 for i in range(lo, hi):
917 yield '%s %s' % (tag, x[i])
919 def _plain_replace(self, a, alo, ahi, b, blo, bhi):
920 assert alo < ahi and blo < bhi
921 # dump the shorter block first -- reduces the burden on short-term
922 # memory if the blocks are of very different sizes
923 if bhi - blo < ahi - alo:
924 first = self._dump('+', b, blo, bhi)
925 second = self._dump('-', a, alo, ahi)
926 else:
927 first = self._dump('-', a, alo, ahi)
928 second = self._dump('+', b, blo, bhi)
930 for g in first, second:
931 yield from g
933 def _fancy_replace(self, a, alo, ahi, b, blo, bhi):
934 r"""
935 When replacing one block of lines with another, search the blocks
936 for *similar* lines; the best-matching pair (if any) is used as a
937 synch point, and intraline difference marking is done on the
938 similar pair. Lots of work, but often worth it.
940 Example:
942 >>> d = Differ()
943 >>> results = d._fancy_replace(['abcDefghiJkl\n'], 0, 1,
944 ... ['abcdefGhijkl\n'], 0, 1)
945 >>> print(''.join(results), end="")
946 - abcDefghiJkl
947 ? ^ ^ ^
948 + abcdefGhijkl
949 ? ^ ^ ^
950 """
952 # don't synch up unless the lines have a similarity score of at
953 # least cutoff; best_ratio tracks the best score seen so far
954 best_ratio, cutoff = 0.74, 0.75
955 cruncher = SequenceMatcher(self.charjunk)
956 eqi, eqj = None, None # 1st indices of equal lines (if any)
958 # search for the pair that matches best without being identical
959 # (identical lines must be junk lines, & we don't want to synch up
960 # on junk -- unless we have to)
961 for j in range(blo, bhi):
962 bj = b[j]
963 cruncher.set_seq2(bj)
964 for i in range(alo, ahi):
965 ai = a[i]
966 if ai == bj:
967 if eqi is None:
968 eqi, eqj = i, j
969 continue
970 cruncher.set_seq1(ai)
971 # computing similarity is expensive, so use the quick
972 # upper bounds first -- have seen this speed up messy
973 # compares by a factor of 3.
974 # note that ratio() is only expensive to compute the first
975 # time it's called on a sequence pair; the expensive part
976 # of the computation is cached by cruncher
977 if cruncher.real_quick_ratio() > best_ratio and \
978 cruncher.quick_ratio() > best_ratio and \
979 cruncher.ratio() > best_ratio:
980 best_ratio, best_i, best_j = cruncher.ratio(), i, j
981 if best_ratio < cutoff:
982 # no non-identical "pretty close" pair
983 if eqi is None:
984 # no identical pair either -- treat it as a straight replace
985 yield from self._plain_replace(a, alo, ahi, b, blo, bhi)
986 return
987 # no close pair, but an identical pair -- synch up on that
988 best_i, best_j, best_ratio = eqi, eqj, 1.0
989 else:
990 # there's a close pair, so forget the identical pair (if any)
991 eqi = None
993 # a[best_i] very similar to b[best_j]; eqi is None iff they're not
994 # identical
996 # pump out diffs from before the synch point
997 yield from self._fancy_helper(a, alo, best_i, b, blo, best_j)
999 # do intraline marking on the synch pair
1000 aelt, belt = a[best_i], b[best_j]
1001 if eqi is None:
1002 # pump out a '-', '?', '+', '?' quad for the synched lines
1003 atags = btags = ""
1004 cruncher.set_seqs(aelt, belt)
1005 for tag, ai1, ai2, bj1, bj2 in cruncher.get_opcodes():
1006 la, lb = ai2 - ai1, bj2 - bj1
1007 if tag == 'replace':
1008 atags += '^' * la
1009 btags += '^' * lb
1010 elif tag == 'delete':
1011 atags += '-' * la
1012 elif tag == 'insert':
1013 btags += '+' * lb
1014 elif tag == 'equal':
1015 atags += ' ' * la
1016 btags += ' ' * lb
1017 else:
1018 raise ValueError('unknown tag %r' % (tag,))
1019 yield from self._qformat(aelt, belt, atags, btags)
1020 else:
1021 # the synch pair is identical
1022 yield ' ' + aelt
1024 # pump out diffs from after the synch point
1025 yield from self._fancy_helper(a, best_i+1, ahi, b, best_j+1, bhi)
1027 def _fancy_helper(self, a, alo, ahi, b, blo, bhi):
1028 g = []
1029 if alo < ahi:
1030 if blo < bhi:
1031 g = self._fancy_replace(a, alo, ahi, b, blo, bhi)
1032 else:
1033 g = self._dump('-', a, alo, ahi)
1034 elif blo < bhi:
1035 g = self._dump('+', b, blo, bhi)
1037 yield from g
1039 def _qformat(self, aline, bline, atags, btags):
1040 r"""
1041 Format "?" output and deal with tabs.
1043 Example:
1045 >>> d = Differ()
1046 >>> results = d._qformat('\tabcDefghiJkl\n', '\tabcdefGhijkl\n',
1047 ... ' ^ ^ ^ ', ' ^ ^ ^ ')
1048 >>> for line in results: print(repr(line))
1049 ...
1050 '- \tabcDefghiJkl\n'
1051 '? \t ^ ^ ^\n'
1052 '+ \tabcdefGhijkl\n'
1053 '? \t ^ ^ ^\n'
1054 """
1055 atags = _keep_original_ws(aline, atags).rstrip()
1056 btags = _keep_original_ws(bline, btags).rstrip()
1058 yield "- " + aline
1059 if atags:
1060 yield f"? {atags}\n"
1062 yield "+ " + bline
1063 if btags:
1064 yield f"? {btags}\n"
1066# With respect to junk, an earlier version of ndiff simply refused to
1067# *start* a match with a junk element. The result was cases like this:
1068# before: private Thread currentThread;
1069# after: private volatile Thread currentThread;
1070# If you consider whitespace to be junk, the longest contiguous match
1071# not starting with junk is "e Thread currentThread". So ndiff reported
1072# that "e volatil" was inserted between the 't' and the 'e' in "private".
1073# While an accurate view, to people that's absurd. The current version
1074# looks for matching blocks that are entirely junk-free, then extends the
1075# longest one of those as far as possible but only with matching junk.
1076# So now "currentThread" is matched, then extended to suck up the
1077# preceding blank; then "private" is matched, and extended to suck up the
1078# following blank; then "Thread" is matched; and finally ndiff reports
1079# that "volatile " was inserted before "Thread". The only quibble
1080# remaining is that perhaps it was really the case that " volatile"
1081# was inserted after "private". I can live with that <wink>.
1083import re
1085def IS_LINE_JUNK(line, pat=re.compile(r"\s*(?:#\s*)?$").match):
1086 r"""
1087 Return True for ignorable line: iff `line` is blank or contains a single '#'.
1089 Examples:
1091 >>> IS_LINE_JUNK('\n')
1092 True
1093 >>> IS_LINE_JUNK(' # \n')
1094 True
1095 >>> IS_LINE_JUNK('hello\n')
1096 False
1097 """
1099 return pat(line) is not None
1101def IS_CHARACTER_JUNK(ch, ws=" \t"):
1102 r"""
1103 Return True for ignorable character: iff `ch` is a space or tab.
1105 Examples:
1107 >>> IS_CHARACTER_JUNK(' ')
1108 True
1109 >>> IS_CHARACTER_JUNK('\t')
1110 True
1111 >>> IS_CHARACTER_JUNK('\n')
1112 False
1113 >>> IS_CHARACTER_JUNK('x')
1114 False
1115 """
1117 return ch in ws
1120########################################################################
1121### Unified Diff
1122########################################################################
1124def _format_range_unified(start, stop):
1125 'Convert range to the "ed" format'
1126 # Per the diff spec at http://www.unix.org/single_unix_specification/
1127 beginning = start + 1 # lines start numbering with one
1128 length = stop - start
1129 if length == 1:
1130 return '{}'.format(beginning)
1131 if not length:
1132 beginning -= 1 # empty ranges begin at line just before the range
1133 return '{},{}'.format(beginning, length)
1135def unified_diff(a, b, fromfile='', tofile='', fromfiledate='',
1136 tofiledate='', n=3, lineterm='\n'):
1137 r"""
1138 Compare two sequences of lines; generate the delta as a unified diff.
1140 Unified diffs are a compact way of showing line changes and a few
1141 lines of context. The number of context lines is set by 'n' which
1142 defaults to three.
1144 By default, the diff control lines (those with ---, +++, or @@) are
1145 created with a trailing newline. This is helpful so that inputs
1146 created from file.readlines() result in diffs that are suitable for
1147 file.writelines() since both the inputs and outputs have trailing
1148 newlines.
1150 For inputs that do not have trailing newlines, set the lineterm
1151 argument to "" so that the output will be uniformly newline free.
1153 The unidiff format normally has a header for filenames and modification
1154 times. Any or all of these may be specified using strings for
1155 'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.
1156 The modification times are normally expressed in the ISO 8601 format.
1158 Example:
1160 >>> for line in unified_diff('one two three four'.split(),
1161 ... 'zero one tree four'.split(), 'Original', 'Current',
1162 ... '2005-01-26 23:30:50', '2010-04-02 10:20:52',
1163 ... lineterm=''):
1164 ... print(line) # doctest: +NORMALIZE_WHITESPACE
1165 --- Original 2005-01-26 23:30:50
1166 +++ Current 2010-04-02 10:20:52
1167 @@ -1,4 +1,4 @@
1168 +zero
1169 one
1170 -two
1171 -three
1172 +tree
1173 four
1174 """
1176 _check_types(a, b, fromfile, tofile, fromfiledate, tofiledate, lineterm)
1177 started = False
1178 for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n):
1179 if not started:
1180 started = True
1181 fromdate = '\t{}'.format(fromfiledate) if fromfiledate else ''
1182 todate = '\t{}'.format(tofiledate) if tofiledate else ''
1183 yield '--- {}{}{}'.format(fromfile, fromdate, lineterm)
1184 yield '+++ {}{}{}'.format(tofile, todate, lineterm)
1186 first, last = group[0], group[-1]
1187 file1_range = _format_range_unified(first[1], last[2])
1188 file2_range = _format_range_unified(first[3], last[4])
1189 yield '@@ -{} +{} @@{}'.format(file1_range, file2_range, lineterm)
1191 for tag, i1, i2, j1, j2 in group:
1192 if tag == 'equal':
1193 for line in a[i1:i2]:
1194 yield ' ' + line
1195 continue
1196 if tag in {'replace', 'delete'}:
1197 for line in a[i1:i2]:
1198 yield '-' + line
1199 if tag in {'replace', 'insert'}:
1200 for line in b[j1:j2]:
1201 yield '+' + line
1204########################################################################
1205### Context Diff
1206########################################################################
1208def _format_range_context(start, stop):
1209 'Convert range to the "ed" format'
1210 # Per the diff spec at http://www.unix.org/single_unix_specification/
1211 beginning = start + 1 # lines start numbering with one
1212 length = stop - start
1213 if not length:
1214 beginning -= 1 # empty ranges begin at line just before the range
1215 if length <= 1:
1216 return '{}'.format(beginning)
1217 return '{},{}'.format(beginning, beginning + length - 1)
1219# See http://www.unix.org/single_unix_specification/
1220def context_diff(a, b, fromfile='', tofile='',
1221 fromfiledate='', tofiledate='', n=3, lineterm='\n'):
1222 r"""
1223 Compare two sequences of lines; generate the delta as a context diff.
1225 Context diffs are a compact way of showing line changes and a few
1226 lines of context. The number of context lines is set by 'n' which
1227 defaults to three.
1229 By default, the diff control lines (those with *** or ---) are
1230 created with a trailing newline. This is helpful so that inputs
1231 created from file.readlines() result in diffs that are suitable for
1232 file.writelines() since both the inputs and outputs have trailing
1233 newlines.
1235 For inputs that do not have trailing newlines, set the lineterm
1236 argument to "" so that the output will be uniformly newline free.
1238 The context diff format normally has a header for filenames and
1239 modification times. Any or all of these may be specified using
1240 strings for 'fromfile', 'tofile', 'fromfiledate', and 'tofiledate'.
1241 The modification times are normally expressed in the ISO 8601 format.
1242 If not specified, the strings default to blanks.
1244 Example:
1246 >>> print(''.join(context_diff('one\ntwo\nthree\nfour\n'.splitlines(True),
1247 ... 'zero\none\ntree\nfour\n'.splitlines(True), 'Original', 'Current')),
1248 ... end="")
1249 *** Original
1250 --- Current
1251 ***************
1252 *** 1,4 ****
1253 one
1254 ! two
1255 ! three
1256 four
1257 --- 1,4 ----
1258 + zero
1259 one
1260 ! tree
1261 four
1262 """
1264 _check_types(a, b, fromfile, tofile, fromfiledate, tofiledate, lineterm)
1265 prefix = dict(insert='+ ', delete='- ', replace='! ', equal=' ')
1266 started = False
1267 for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n):
1268 if not started:
1269 started = True
1270 fromdate = '\t{}'.format(fromfiledate) if fromfiledate else ''
1271 todate = '\t{}'.format(tofiledate) if tofiledate else ''
1272 yield '*** {}{}{}'.format(fromfile, fromdate, lineterm)
1273 yield '--- {}{}{}'.format(tofile, todate, lineterm)
1275 first, last = group[0], group[-1]
1276 yield '***************' + lineterm
1278 file1_range = _format_range_context(first[1], last[2])
1279 yield '*** {} ****{}'.format(file1_range, lineterm)
1281 if any(tag in {'replace', 'delete'} for tag, _, _, _, _ in group):
1282 for tag, i1, i2, _, _ in group:
1283 if tag != 'insert':
1284 for line in a[i1:i2]:
1285 yield prefix[tag] + line
1287 file2_range = _format_range_context(first[3], last[4])
1288 yield '--- {} ----{}'.format(file2_range, lineterm)
1290 if any(tag in {'replace', 'insert'} for tag, _, _, _, _ in group):
1291 for tag, _, _, j1, j2 in group:
1292 if tag != 'delete':
1293 for line in b[j1:j2]:
1294 yield prefix[tag] + line
1296def _check_types(a, b, *args):
1297 # Checking types is weird, but the alternative is garbled output when
1298 # someone passes mixed bytes and str to {unified,context}_diff(). E.g.
1299 # without this check, passing filenames as bytes results in output like
1300 # --- b'oldfile.txt'
1301 # +++ b'newfile.txt'
1302 # because of how str.format() incorporates bytes objects.
1303 if a and not isinstance(a[0], str):
1304 raise TypeError('lines to compare must be str, not %s (%r)' %
1305 (type(a[0]).__name__, a[0]))
1306 if b and not isinstance(b[0], str):
1307 raise TypeError('lines to compare must be str, not %s (%r)' %
1308 (type(b[0]).__name__, b[0]))
1309 for arg in args:
1310 if not isinstance(arg, str):
1311 raise TypeError('all arguments must be str, not: %r' % (arg,))
1313def diff_bytes(dfunc, a, b, fromfile=b'', tofile=b'',
1314 fromfiledate=b'', tofiledate=b'', n=3, lineterm=b'\n'):
1315 r"""
1316 Compare `a` and `b`, two sequences of lines represented as bytes rather
1317 than str. This is a wrapper for `dfunc`, which is typically either
1318 unified_diff() or context_diff(). Inputs are losslessly converted to
1319 strings so that `dfunc` only has to worry about strings, and encoded
1320 back to bytes on return. This is necessary to compare files with
1321 unknown or inconsistent encoding. All other inputs (except `n`) must be
1322 bytes rather than str.
1323 """
1324 def decode(s):
1325 try:
1326 return s.decode('ascii', 'surrogateescape')
1327 except AttributeError as err:
1328 msg = ('all arguments must be bytes, not %s (%r)' %
1329 (type(s).__name__, s))
1330 raise TypeError(msg) from err
1331 a = list(map(decode, a))
1332 b = list(map(decode, b))
1333 fromfile = decode(fromfile)
1334 tofile = decode(tofile)
1335 fromfiledate = decode(fromfiledate)
1336 tofiledate = decode(tofiledate)
1337 lineterm = decode(lineterm)
1339 lines = dfunc(a, b, fromfile, tofile, fromfiledate, tofiledate, n, lineterm)
1340 for line in lines:
1341 yield line.encode('ascii', 'surrogateescape')
1343def ndiff(a, b, linejunk=None, charjunk=IS_CHARACTER_JUNK):
1344 r"""
1345 Compare `a` and `b` (lists of strings); return a `Differ`-style delta.
1347 Optional keyword parameters `linejunk` and `charjunk` are for filter
1348 functions, or can be None:
1350 - linejunk: A function that should accept a single string argument and
1351 return true iff the string is junk. The default is None, and is
1352 recommended; the underlying SequenceMatcher class has an adaptive
1353 notion of "noise" lines.
1355 - charjunk: A function that accepts a character (string of length
1356 1), and returns true iff the character is junk. The default is
1357 the module-level function IS_CHARACTER_JUNK, which filters out
1358 whitespace characters (a blank or tab; note: it's a bad idea to
1359 include newline in this!).
1361 Tools/scripts/ndiff.py is a command-line front-end to this function.
1363 Example:
1365 >>> diff = ndiff('one\ntwo\nthree\n'.splitlines(keepends=True),
1366 ... 'ore\ntree\nemu\n'.splitlines(keepends=True))
1367 >>> print(''.join(diff), end="")
1368 - one
1369 ? ^
1370 + ore
1371 ? ^
1372 - two
1373 - three
1374 ? -
1375 + tree
1376 + emu
1377 """
1378 return Differ(linejunk, charjunk).compare(a, b)
1380def _mdiff(fromlines, tolines, context=None, linejunk=None,
1381 charjunk=IS_CHARACTER_JUNK):
1382 r"""Returns generator yielding marked up from/to side by side differences.
1384 Arguments:
1385 fromlines -- list of text lines to compared to tolines
1386 tolines -- list of text lines to be compared to fromlines
1387 context -- number of context lines to display on each side of difference,
1388 if None, all from/to text lines will be generated.
1389 linejunk -- passed on to ndiff (see ndiff documentation)
1390 charjunk -- passed on to ndiff (see ndiff documentation)
1392 This function returns an iterator which returns a tuple:
1393 (from line tuple, to line tuple, boolean flag)
1395 from/to line tuple -- (line num, line text)
1396 line num -- integer or None (to indicate a context separation)
1397 line text -- original line text with following markers inserted:
1398 '\0+' -- marks start of added text
1399 '\0-' -- marks start of deleted text
1400 '\0^' -- marks start of changed text
1401 '\1' -- marks end of added/deleted/changed text
1403 boolean flag -- None indicates context separation, True indicates
1404 either "from" or "to" line contains a change, otherwise False.
1406 This function/iterator was originally developed to generate side by side
1407 file difference for making HTML pages (see HtmlDiff class for example
1408 usage).
1410 Note, this function utilizes the ndiff function to generate the side by
1411 side difference markup. Optional ndiff arguments may be passed to this
1412 function and they in turn will be passed to ndiff.
1413 """
1414 import re
1416 # regular expression for finding intraline change indices
1417 change_re = re.compile(r'(\++|\-+|\^+)')
1419 # create the difference iterator to generate the differences
1420 diff_lines_iterator = ndiff(fromlines,tolines,linejunk,charjunk)
1422 def _make_line(lines, format_key, side, num_lines=[0,0]):
1423 """Returns line of text with user's change markup and line formatting.
1425 lines -- list of lines from the ndiff generator to produce a line of
1426 text from. When producing the line of text to return, the
1427 lines used are removed from this list.
1428 format_key -- '+' return first line in list with "add" markup around
1429 the entire line.
1430 '-' return first line in list with "delete" markup around
1431 the entire line.
1432 '?' return first line in list with add/delete/change
1433 intraline markup (indices obtained from second line)
1434 None return first line in list with no markup
1435 side -- indice into the num_lines list (0=from,1=to)
1436 num_lines -- from/to current line number. This is NOT intended to be a
1437 passed parameter. It is present as a keyword argument to
1438 maintain memory of the current line numbers between calls
1439 of this function.
1441 Note, this function is purposefully not defined at the module scope so
1442 that data it needs from its parent function (within whose context it
1443 is defined) does not need to be of module scope.
1444 """
1445 num_lines[side] += 1
1446 # Handle case where no user markup is to be added, just return line of
1447 # text with user's line format to allow for usage of the line number.
1448 if format_key is None:
1449 return (num_lines[side],lines.pop(0)[2:])
1450 # Handle case of intraline changes
1451 if format_key == '?':
1452 text, markers = lines.pop(0), lines.pop(0)
1453 # find intraline changes (store change type and indices in tuples)
1454 sub_info = []
1455 def record_sub_info(match_object,sub_info=sub_info):
1456 sub_info.append([match_object.group(1)[0],match_object.span()])
1457 return match_object.group(1)
1458 change_re.sub(record_sub_info,markers)
1459 # process each tuple inserting our special marks that won't be
1460 # noticed by an xml/html escaper.
1461 for key,(begin,end) in reversed(sub_info):
1462 text = text[0:begin]+'\0'+key+text[begin:end]+'\1'+text[end:]
1463 text = text[2:]
1464 # Handle case of add/delete entire line
1465 else:
1466 text = lines.pop(0)[2:]
1467 # if line of text is just a newline, insert a space so there is
1468 # something for the user to highlight and see.
1469 if not text:
1470 text = ' '
1471 # insert marks that won't be noticed by an xml/html escaper.
1472 text = '\0' + format_key + text + '\1'
1473 # Return line of text, first allow user's line formatter to do its
1474 # thing (such as adding the line number) then replace the special
1475 # marks with what the user's change markup.
1476 return (num_lines[side],text)
1478 def _line_iterator():
1479 """Yields from/to lines of text with a change indication.
1481 This function is an iterator. It itself pulls lines from a
1482 differencing iterator, processes them and yields them. When it can
1483 it yields both a "from" and a "to" line, otherwise it will yield one
1484 or the other. In addition to yielding the lines of from/to text, a
1485 boolean flag is yielded to indicate if the text line(s) have
1486 differences in them.
1488 Note, this function is purposefully not defined at the module scope so
1489 that data it needs from its parent function (within whose context it
1490 is defined) does not need to be of module scope.
1491 """
1492 lines = []
1493 num_blanks_pending, num_blanks_to_yield = 0, 0
1494 while True:
1495 # Load up next 4 lines so we can look ahead, create strings which
1496 # are a concatenation of the first character of each of the 4 lines
1497 # so we can do some very readable comparisons.
1498 while len(lines) < 4:
1499 lines.append(next(diff_lines_iterator, 'X'))
1500 s = ''.join([line[0] for line in lines])
1501 if s.startswith('X'):
1502 # When no more lines, pump out any remaining blank lines so the
1503 # corresponding add/delete lines get a matching blank line so
1504 # all line pairs get yielded at the next level.
1505 num_blanks_to_yield = num_blanks_pending
1506 elif s.startswith('-?+?'):
1507 # simple intraline change
1508 yield _make_line(lines,'?',0), _make_line(lines,'?',1), True
1509 continue
1510 elif s.startswith('--++'):
1511 # in delete block, add block coming: we do NOT want to get
1512 # caught up on blank lines yet, just process the delete line
1513 num_blanks_pending -= 1
1514 yield _make_line(lines,'-',0), None, True
1515 continue
1516 elif s.startswith(('--?+', '--+', '- ')):
1517 # in delete block and see an intraline change or unchanged line
1518 # coming: yield the delete line and then blanks
1519 from_line,to_line = _make_line(lines,'-',0), None
1520 num_blanks_to_yield,num_blanks_pending = num_blanks_pending-1,0
1521 elif s.startswith('-+?'):
1522 # intraline change
1523 yield _make_line(lines,None,0), _make_line(lines,'?',1), True
1524 continue
1525 elif s.startswith('-?+'):
1526 # intraline change
1527 yield _make_line(lines,'?',0), _make_line(lines,None,1), True
1528 continue
1529 elif s.startswith('-'):
1530 # delete FROM line
1531 num_blanks_pending -= 1
1532 yield _make_line(lines,'-',0), None, True
1533 continue
1534 elif s.startswith('+--'):
1535 # in add block, delete block coming: we do NOT want to get
1536 # caught up on blank lines yet, just process the add line
1537 num_blanks_pending += 1
1538 yield None, _make_line(lines,'+',1), True
1539 continue
1540 elif s.startswith(('+ ', '+-')):
1541 # will be leaving an add block: yield blanks then add line
1542 from_line, to_line = None, _make_line(lines,'+',1)
1543 num_blanks_to_yield,num_blanks_pending = num_blanks_pending+1,0
1544 elif s.startswith('+'):
1545 # inside an add block, yield the add line
1546 num_blanks_pending += 1
1547 yield None, _make_line(lines,'+',1), True
1548 continue
1549 elif s.startswith(' '):
1550 # unchanged text, yield it to both sides
1551 yield _make_line(lines[:],None,0),_make_line(lines,None,1),False
1552 continue
1553 # Catch up on the blank lines so when we yield the next from/to
1554 # pair, they are lined up.
1555 while(num_blanks_to_yield < 0):
1556 num_blanks_to_yield += 1
1557 yield None,('','\n'),True
1558 while(num_blanks_to_yield > 0):
1559 num_blanks_to_yield -= 1
1560 yield ('','\n'),None,True
1561 if s.startswith('X'):
1562 return
1563 else:
1564 yield from_line,to_line,True
1566 def _line_pair_iterator():
1567 """Yields from/to lines of text with a change indication.
1569 This function is an iterator. It itself pulls lines from the line
1570 iterator. Its difference from that iterator is that this function
1571 always yields a pair of from/to text lines (with the change
1572 indication). If necessary it will collect single from/to lines
1573 until it has a matching pair from/to pair to yield.
1575 Note, this function is purposefully not defined at the module scope so
1576 that data it needs from its parent function (within whose context it
1577 is defined) does not need to be of module scope.
1578 """
1579 line_iterator = _line_iterator()
1580 fromlines,tolines=[],[]
1581 while True:
1582 # Collecting lines of text until we have a from/to pair
1583 while (len(fromlines)==0 or len(tolines)==0):
1584 try:
1585 from_line, to_line, found_diff = next(line_iterator)
1586 except StopIteration:
1587 return
1588 if from_line is not None:
1589 fromlines.append((from_line,found_diff))
1590 if to_line is not None:
1591 tolines.append((to_line,found_diff))
1592 # Once we have a pair, remove them from the collection and yield it
1593 from_line, fromDiff = fromlines.pop(0)
1594 to_line, to_diff = tolines.pop(0)
1595 yield (from_line,to_line,fromDiff or to_diff)
1597 # Handle case where user does not want context differencing, just yield
1598 # them up without doing anything else with them.
1599 line_pair_iterator = _line_pair_iterator()
1600 if context is None:
1601 yield from line_pair_iterator
1602 # Handle case where user wants context differencing. We must do some
1603 # storage of lines until we know for sure that they are to be yielded.
1604 else:
1605 context += 1
1606 lines_to_write = 0
1607 while True:
1608 # Store lines up until we find a difference, note use of a
1609 # circular queue because we only need to keep around what
1610 # we need for context.
1611 index, contextLines = 0, [None]*(context)
1612 found_diff = False
1613 while(found_diff is False):
1614 try:
1615 from_line, to_line, found_diff = next(line_pair_iterator)
1616 except StopIteration:
1617 return
1618 i = index % context
1619 contextLines[i] = (from_line, to_line, found_diff)
1620 index += 1
1621 # Yield lines that we have collected so far, but first yield
1622 # the user's separator.
1623 if index > context:
1624 yield None, None, None
1625 lines_to_write = context
1626 else:
1627 lines_to_write = index
1628 index = 0
1629 while(lines_to_write):
1630 i = index % context
1631 index += 1
1632 yield contextLines[i]
1633 lines_to_write -= 1
1634 # Now yield the context lines after the change
1635 lines_to_write = context-1
1636 try:
1637 while(lines_to_write):
1638 from_line, to_line, found_diff = next(line_pair_iterator)
1639 # If another change within the context, extend the context
1640 if found_diff:
1641 lines_to_write = context-1
1642 else:
1643 lines_to_write -= 1
1644 yield from_line, to_line, found_diff
1645 except StopIteration:
1646 # Catch exception from next() and return normally
1647 return
1650_file_template = """
1651<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
1652 "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
1654<html>
1656<head>
1657 <meta http-equiv="Content-Type"
1658 content="text/html; charset=%(charset)s" />
1659 <title></title>
1660 <style type="text/css">%(styles)s
1661 </style>
1662</head>
1664<body>
1665 %(table)s%(legend)s
1666</body>
1668</html>"""
1670_styles = """
1671 table.diff {font-family:Courier; border:medium;}
1672 .diff_header {background-color:#e0e0e0}
1673 td.diff_header {text-align:right}
1674 .diff_next {background-color:#c0c0c0}
1675 .diff_add {background-color:#aaffaa}
1676 .diff_chg {background-color:#ffff77}
1677 .diff_sub {background-color:#ffaaaa}"""
1679_table_template = """
1680 <table class="diff" id="difflib_chg_%(prefix)s_top"
1681 cellspacing="0" cellpadding="0" rules="groups" >
1682 <colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
1683 <colgroup></colgroup> <colgroup></colgroup> <colgroup></colgroup>
1684 %(header_row)s
1685 <tbody>
1686%(data_rows)s </tbody>
1687 </table>"""
1689_legend = """
1690 <table class="diff" summary="Legends">
1691 <tr> <th colspan="2"> Legends </th> </tr>
1692 <tr> <td> <table border="" summary="Colors">
1693 <tr><th> Colors </th> </tr>
1694 <tr><td class="diff_add"> Added </td></tr>
1695 <tr><td class="diff_chg">Changed</td> </tr>
1696 <tr><td class="diff_sub">Deleted</td> </tr>
1697 </table></td>
1698 <td> <table border="" summary="Links">
1699 <tr><th colspan="2"> Links </th> </tr>
1700 <tr><td>(f)irst change</td> </tr>
1701 <tr><td>(n)ext change</td> </tr>
1702 <tr><td>(t)op</td> </tr>
1703 </table></td> </tr>
1704 </table>"""
1706class HtmlDiff(object):
1707 """For producing HTML side by side comparison with change highlights.
1709 This class can be used to create an HTML table (or a complete HTML file
1710 containing the table) showing a side by side, line by line comparison
1711 of text with inter-line and intra-line change highlights. The table can
1712 be generated in either full or contextual difference mode.
1714 The following methods are provided for HTML generation:
1716 make_table -- generates HTML for a single side by side table
1717 make_file -- generates complete HTML file with a single side by side table
1719 See tools/scripts/diff.py for an example usage of this class.
1720 """
1722 _file_template = _file_template
1723 _styles = _styles
1724 _table_template = _table_template
1725 _legend = _legend
1726 _default_prefix = 0
1728 def __init__(self,tabsize=8,wrapcolumn=None,linejunk=None,
1729 charjunk=IS_CHARACTER_JUNK):
1730 """HtmlDiff instance initializer
1732 Arguments:
1733 tabsize -- tab stop spacing, defaults to 8.
1734 wrapcolumn -- column number where lines are broken and wrapped,
1735 defaults to None where lines are not wrapped.
1736 linejunk,charjunk -- keyword arguments passed into ndiff() (used by
1737 HtmlDiff() to generate the side by side HTML differences). See
1738 ndiff() documentation for argument default values and descriptions.
1739 """
1740 self._tabsize = tabsize
1741 self._wrapcolumn = wrapcolumn
1742 self._linejunk = linejunk
1743 self._charjunk = charjunk
1745 def make_file(self, fromlines, tolines, fromdesc='', todesc='',
1746 context=False, numlines=5, *, charset='utf-8'):
1747 """Returns HTML file of side by side comparison with change highlights
1749 Arguments:
1750 fromlines -- list of "from" lines
1751 tolines -- list of "to" lines
1752 fromdesc -- "from" file column header string
1753 todesc -- "to" file column header string
1754 context -- set to True for contextual differences (defaults to False
1755 which shows full differences).
1756 numlines -- number of context lines. When context is set True,
1757 controls number of lines displayed before and after the change.
1758 When context is False, controls the number of lines to place
1759 the "next" link anchors before the next change (so click of
1760 "next" link jumps to just before the change).
1761 charset -- charset of the HTML document
1762 """
1764 return (self._file_template % dict(
1765 styles=self._styles,
1766 legend=self._legend,
1767 table=self.make_table(fromlines, tolines, fromdesc, todesc,
1768 context=context, numlines=numlines),
1769 charset=charset
1770 )).encode(charset, 'xmlcharrefreplace').decode(charset)
1772 def _tab_newline_replace(self,fromlines,tolines):
1773 """Returns from/to line lists with tabs expanded and newlines removed.
1775 Instead of tab characters being replaced by the number of spaces
1776 needed to fill in to the next tab stop, this function will fill
1777 the space with tab characters. This is done so that the difference
1778 algorithms can identify changes in a file when tabs are replaced by
1779 spaces and vice versa. At the end of the HTML generation, the tab
1780 characters will be replaced with a nonbreakable space.
1781 """
1782 def expand_tabs(line):
1783 # hide real spaces
1784 line = line.replace(' ','\0')
1785 # expand tabs into spaces
1786 line = line.expandtabs(self._tabsize)
1787 # replace spaces from expanded tabs back into tab characters
1788 # (we'll replace them with markup after we do differencing)
1789 line = line.replace(' ','\t')
1790 return line.replace('\0',' ').rstrip('\n')
1791 fromlines = [expand_tabs(line) for line in fromlines]
1792 tolines = [expand_tabs(line) for line in tolines]
1793 return fromlines,tolines
1795 def _split_line(self,data_list,line_num,text):
1796 """Builds list of text lines by splitting text lines at wrap point
1798 This function will determine if the input text line needs to be
1799 wrapped (split) into separate lines. If so, the first wrap point
1800 will be determined and the first line appended to the output
1801 text line list. This function is used recursively to handle
1802 the second part of the split line to further split it.
1803 """
1804 # if blank line or context separator, just add it to the output list
1805 if not line_num:
1806 data_list.append((line_num,text))
1807 return
1809 # if line text doesn't need wrapping, just add it to the output list
1810 size = len(text)
1811 max = self._wrapcolumn
1812 if (size <= max) or ((size -(text.count('\0')*3)) <= max):
1813 data_list.append((line_num,text))
1814 return
1816 # scan text looking for the wrap point, keeping track if the wrap
1817 # point is inside markers
1818 i = 0
1819 n = 0
1820 mark = ''
1821 while n < max and i < size:
1822 if text[i] == '\0':
1823 i += 1
1824 mark = text[i]
1825 i += 1
1826 elif text[i] == '\1':
1827 i += 1
1828 mark = ''
1829 else:
1830 i += 1
1831 n += 1
1833 # wrap point is inside text, break it up into separate lines
1834 line1 = text[:i]
1835 line2 = text[i:]
1837 # if wrap point is inside markers, place end marker at end of first
1838 # line and start marker at beginning of second line because each
1839 # line will have its own table tag markup around it.
1840 if mark:
1841 line1 = line1 + '\1'
1842 line2 = '\0' + mark + line2
1844 # tack on first line onto the output list
1845 data_list.append((line_num,line1))
1847 # use this routine again to wrap the remaining text
1848 self._split_line(data_list,'>',line2)
1850 def _line_wrapper(self,diffs):
1851 """Returns iterator that splits (wraps) mdiff text lines"""
1853 # pull from/to data and flags from mdiff iterator
1854 for fromdata,todata,flag in diffs:
1855 # check for context separators and pass them through
1856 if flag is None:
1857 yield fromdata,todata,flag
1858 continue
1859 (fromline,fromtext),(toline,totext) = fromdata,todata
1860 # for each from/to line split it at the wrap column to form
1861 # list of text lines.
1862 fromlist,tolist = [],[]
1863 self._split_line(fromlist,fromline,fromtext)
1864 self._split_line(tolist,toline,totext)
1865 # yield from/to line in pairs inserting blank lines as
1866 # necessary when one side has more wrapped lines
1867 while fromlist or tolist:
1868 if fromlist:
1869 fromdata = fromlist.pop(0)
1870 else:
1871 fromdata = ('',' ')
1872 if tolist:
1873 todata = tolist.pop(0)
1874 else:
1875 todata = ('',' ')
1876 yield fromdata,todata,flag
1878 def _collect_lines(self,diffs):
1879 """Collects mdiff output into separate lists
1881 Before storing the mdiff from/to data into a list, it is converted
1882 into a single line of text with HTML markup.
1883 """
1885 fromlist,tolist,flaglist = [],[],[]
1886 # pull from/to data and flags from mdiff style iterator
1887 for fromdata,todata,flag in diffs:
1888 try:
1889 # store HTML markup of the lines into the lists
1890 fromlist.append(self._format_line(0,flag,*fromdata))
1891 tolist.append(self._format_line(1,flag,*todata))
1892 except TypeError:
1893 # exceptions occur for lines where context separators go
1894 fromlist.append(None)
1895 tolist.append(None)
1896 flaglist.append(flag)
1897 return fromlist,tolist,flaglist
1899 def _format_line(self,side,flag,linenum,text):
1900 """Returns HTML markup of "from" / "to" text lines
1902 side -- 0 or 1 indicating "from" or "to" text
1903 flag -- indicates if difference on line
1904 linenum -- line number (used for line number column)
1905 text -- line text to be marked up
1906 """
1907 try:
1908 linenum = '%d' % linenum
1909 id = ' id="%s%s"' % (self._prefix[side],linenum)
1910 except TypeError:
1911 # handle blank lines where linenum is '>' or ''
1912 id = ''
1913 # replace those things that would get confused with HTML symbols
1914 text=text.replace("&","&").replace(">",">").replace("<","<")
1916 # make space non-breakable so they don't get compressed or line wrapped
1917 text = text.replace(' ',' ').rstrip()
1919 return '<td class="diff_header"%s>%s</td><td nowrap="nowrap">%s</td>' \
1920 % (id,linenum,text)
1922 def _make_prefix(self):
1923 """Create unique anchor prefixes"""
1925 # Generate a unique anchor prefix so multiple tables
1926 # can exist on the same HTML page without conflicts.
1927 fromprefix = "from%d_" % HtmlDiff._default_prefix
1928 toprefix = "to%d_" % HtmlDiff._default_prefix
1929 HtmlDiff._default_prefix += 1
1930 # store prefixes so line format method has access
1931 self._prefix = [fromprefix,toprefix]
1933 def _convert_flags(self,fromlist,tolist,flaglist,context,numlines):
1934 """Makes list of "next" links"""
1936 # all anchor names will be generated using the unique "to" prefix
1937 toprefix = self._prefix[1]
1939 # process change flags, generating middle column of next anchors/links
1940 next_id = ['']*len(flaglist)
1941 next_href = ['']*len(flaglist)
1942 num_chg, in_change = 0, False
1943 last = 0
1944 for i,flag in enumerate(flaglist):
1945 if flag:
1946 if not in_change:
1947 in_change = True
1948 last = i
1949 # at the beginning of a change, drop an anchor a few lines
1950 # (the context lines) before the change for the previous
1951 # link
1952 i = max([0,i-numlines])
1953 next_id[i] = ' id="difflib_chg_%s_%d"' % (toprefix,num_chg)
1954 # at the beginning of a change, drop a link to the next
1955 # change
1956 num_chg += 1
1957 next_href[last] = '<a href="#difflib_chg_%s_%d">n</a>' % (
1958 toprefix,num_chg)
1959 else:
1960 in_change = False
1961 # check for cases where there is no content to avoid exceptions
1962 if not flaglist:
1963 flaglist = [False]
1964 next_id = ['']
1965 next_href = ['']
1966 last = 0
1967 if context:
1968 fromlist = ['<td></td><td> No Differences Found </td>']
1969 tolist = fromlist
1970 else:
1971 fromlist = tolist = ['<td></td><td> Empty File </td>']
1972 # if not a change on first line, drop a link
1973 if not flaglist[0]:
1974 next_href[0] = '<a href="#difflib_chg_%s_0">f</a>' % toprefix
1975 # redo the last link to link to the top
1976 next_href[last] = '<a href="#difflib_chg_%s_top">t</a>' % (toprefix)
1978 return fromlist,tolist,flaglist,next_href,next_id
1980 def make_table(self,fromlines,tolines,fromdesc='',todesc='',context=False,
1981 numlines=5):
1982 """Returns HTML table of side by side comparison with change highlights
1984 Arguments:
1985 fromlines -- list of "from" lines
1986 tolines -- list of "to" lines
1987 fromdesc -- "from" file column header string
1988 todesc -- "to" file column header string
1989 context -- set to True for contextual differences (defaults to False
1990 which shows full differences).
1991 numlines -- number of context lines. When context is set True,
1992 controls number of lines displayed before and after the change.
1993 When context is False, controls the number of lines to place
1994 the "next" link anchors before the next change (so click of
1995 "next" link jumps to just before the change).
1996 """
1998 # make unique anchor prefixes so that multiple tables may exist
1999 # on the same page without conflict.
2000 self._make_prefix()
2002 # change tabs to spaces before it gets more difficult after we insert
2003 # markup
2004 fromlines,tolines = self._tab_newline_replace(fromlines,tolines)
2006 # create diffs iterator which generates side by side from/to data
2007 if context:
2008 context_lines = numlines
2009 else:
2010 context_lines = None
2011 diffs = _mdiff(fromlines,tolines,context_lines,linejunk=self._linejunk,
2012 charjunk=self._charjunk)
2014 # set up iterator to wrap lines that exceed desired width
2015 if self._wrapcolumn:
2016 diffs = self._line_wrapper(diffs)
2018 # collect up from/to lines and flags into lists (also format the lines)
2019 fromlist,tolist,flaglist = self._collect_lines(diffs)
2021 # process change flags, generating middle column of next anchors/links
2022 fromlist,tolist,flaglist,next_href,next_id = self._convert_flags(
2023 fromlist,tolist,flaglist,context,numlines)
2025 s = []
2026 fmt = ' <tr><td class="diff_next"%s>%s</td>%s' + \
2027 '<td class="diff_next">%s</td>%s</tr>\n'
2028 for i in range(len(flaglist)):
2029 if flaglist[i] is None:
2030 # mdiff yields None on separator lines skip the bogus ones
2031 # generated for the first line
2032 if i > 0:
2033 s.append(' </tbody> \n <tbody>\n')
2034 else:
2035 s.append( fmt % (next_id[i],next_href[i],fromlist[i],
2036 next_href[i],tolist[i]))
2037 if fromdesc or todesc:
2038 header_row = '<thead><tr>%s%s%s%s</tr></thead>' % (
2039 '<th class="diff_next"><br /></th>',
2040 '<th colspan="2" class="diff_header">%s</th>' % fromdesc,
2041 '<th class="diff_next"><br /></th>',
2042 '<th colspan="2" class="diff_header">%s</th>' % todesc)
2043 else:
2044 header_row = ''
2046 table = self._table_template % dict(
2047 data_rows=''.join(s),
2048 header_row=header_row,
2049 prefix=self._prefix[1])
2051 return table.replace('\0+','<span class="diff_add">'). \
2052 replace('\0-','<span class="diff_sub">'). \
2053 replace('\0^','<span class="diff_chg">'). \
2054 replace('\1','</span>'). \
2055 replace('\t',' ')
2057del re
2059def restore(delta, which):
2060 r"""
2061 Generate one of the two sequences that generated a delta.
2063 Given a `delta` produced by `Differ.compare()` or `ndiff()`, extract
2064 lines originating from file 1 or 2 (parameter `which`), stripping off line
2065 prefixes.
2067 Examples:
2069 >>> diff = ndiff('one\ntwo\nthree\n'.splitlines(keepends=True),
2070 ... 'ore\ntree\nemu\n'.splitlines(keepends=True))
2071 >>> diff = list(diff)
2072 >>> print(''.join(restore(diff, 1)), end="")
2073 one
2074 two
2075 three
2076 >>> print(''.join(restore(diff, 2)), end="")
2077 ore
2078 tree
2079 emu
2080 """
2081 try:
2082 tag = {1: "- ", 2: "+ "}[int(which)]
2083 except KeyError:
2084 raise ValueError('unknown delta choice (must be 1 or 2): %r'
2085 % which) from None
2086 prefixes = (" ", tag)
2087 for line in delta:
2088 if line[:2] in prefixes:
2089 yield line[2:]
2091def _test():
2092 import doctest, difflib
2093 return doctest.testmod(difflib)
2095if __name__ == "__main__":
2096 _test()