#! /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='', autojunk=True): | |
"""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(). | |
Optional arg autojunk should be set to False to disable the | |
"automatic junk heuristic" that treats popular elements as junk | |
(see module documentation for more information). | |
""" | |
# 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 + 1% of | |
# its elements (when autojunk is enabled). | |
# DOES NOT WORK for x in a! | |
self.isjunk = isjunk | |
self.a = self.b = None | |
self.autojunk = autojunk | |
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 + 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 | |
self.b2j = b2j = {} | |
for i, elt in enumerate(b): | |
indices = b2j.setdefault(elt, []) | |
indices.append(i) | |
# Purge junk elements | |
junk = set() | |
isjunk = self.isjunk | |
if isjunk: | |
for elt in list(b2j.keys()): # using list() since b2j is modified | |
if isjunk(elt): | |
junk.add(elt) | |
del b2j[elt] | |
# Purge popular elements that are not junk | |
popular = set() | |
n = len(b) | |
if self.autojunk and n >= 200: | |
ntest = n // 100 + 1 | |
for elt, idxs in list(b2j.items()): | |
if len(idxs) > ntest: | |
popular.add(elt) | |
del b2j[elt] | |
# Now for x in b, isjunk(x) == x in junk, but the latter is much faster. | |
# Sicne the number of *unique* junk elements is probably small, the | |
# memory burden of keeping this set alive is likely trivial compared to | |
# the size of b2j. | |
self.isbjunk = junk.__contains__ | |
self.isbpopular = popular.__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', '\tabcdefGhijkl\n', | |
... ' ^ ^ ^ ', ' ^ ^ ^ ') | |
>>> for line in results: print repr(line) | |
... | |
'- \tabcDefghiJkl\n' | |
'? \t ^ ^ ^\n' | |
'+ \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], " ")) | |
common = min(common, _count_leading(btags[: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 | |
######################################################################## | |
### Unified Diff | |
######################################################################## | |
def _format_range_unified(start, stop): | |
'Convert range to the "ed" format' | |
# Per the diff spec at http://www.unix.org/single_unix_specification/ | |
beginning = start + 1 # lines start numbering with one | |
length = stop - start | |
if length == 1: | |
return '{}'.format(beginning) | |
if not length: | |
beginning -= 1 # empty ranges begin at line just before the range | |
return '{},{}'.format(beginning, length) | |
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 ISO 8601 format. | |
Example: | |
>>> for line in unified_diff('one two three four'.split(), | |
... 'zero one tree four'.split(), 'Original', 'Current', | |
... '2005-01-26 23:30:50', '2010-04-02 10:20:52', | |
... lineterm=''): | |
... print line # doctest: +NORMALIZE_WHITESPACE | |
--- Original 2005-01-26 23:30:50 | |
+++ Current 2010-04-02 10:20:52 | |
@@ -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: | |
started = True | |
fromdate = '\t{}'.format(fromfiledate) if fromfiledate else '' | |
todate = '\t{}'.format(tofiledate) if tofiledate else '' | |
yield '--- {}{}{}'.format(fromfile, fromdate, lineterm) | |
yield '+++ {}{}{}'.format(tofile, todate, lineterm) | |
first, last = group[0], group[-1] | |
file1_range = _format_range_unified(first[1], last[2]) | |
file2_range = _format_range_unified(first[3], last[4]) | |
yield '@@ -{} +{} @@{}'.format(file1_range, file2_range, lineterm) | |
for tag, i1, i2, j1, j2 in group: | |
if tag == 'equal': | |
for line in a[i1:i2]: | |
yield ' ' + line | |
continue | |
if tag in ('replace', 'delete'): | |
for line in a[i1:i2]: | |
yield '-' + line | |
if tag in ('replace', 'insert'): | |
for line in b[j1:j2]: | |
yield '+' + line | |
######################################################################## | |
### Context Diff | |
######################################################################## | |
def _format_range_context(start, stop): | |
'Convert range to the "ed" format' | |
# Per the diff spec at http://www.unix.org/single_unix_specification/ | |
beginning = start + 1 # lines start numbering with one | |
length = stop - start | |
if not length: | |
beginning -= 1 # empty ranges begin at line just before the range | |
if length <= 1: | |
return '{}'.format(beginning) | |
return '{},{}'.format(beginning, beginning + length - 1) | |
# 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 ISO 8601 format. | |
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')), | |
*** Original | |
--- Current | |
*************** | |
*** 1,4 **** | |
one | |
! two | |
! three | |
four | |
--- 1,4 ---- | |
+ zero | |
one | |
! tree | |
four | |
""" | |
prefix = dict(insert='+ ', delete='- ', replace='! ', equal=' ') | |
started = False | |
for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n): | |
if not started: | |
started = True | |
fromdate = '\t{}'.format(fromfiledate) if fromfiledate else '' | |
todate = '\t{}'.format(tofiledate) if tofiledate else '' | |
yield '*** {}{}{}'.format(fromfile, fromdate, lineterm) | |
yield '--- {}{}{}'.format(tofile, todate, lineterm) | |
first, last = group[0], group[-1] | |
yield '***************' + lineterm | |
file1_range = _format_range_context(first[1], last[2]) | |
yield '*** {} ****{}'.format(file1_range, lineterm) | |
if any(tag in ('replace', 'delete') for tag, _, _, _, _ in group): | |
for tag, i1, i2, _, _ in group: | |
if tag != 'insert': | |
for line in a[i1:i2]: | |
yield prefix[tag] + line | |
file2_range = _format_range_context(first[3], last[4]) | |
yield '--- {} ----{}'.format(file2_range, lineterm) | |
if any(tag in ('replace', 'insert') for tag, _, _, _, _ in group): | |
for tag, _, _, j1, j2 in group: | |
if tag != 'delete': | |
for line in b[j1:j2]: | |
yield prefix[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 separation) | |
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"> Added </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) | |
# replace 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("&","&").replace(">",">").replace("<","<") | |
# make space non-breakable so they don't get compressed or line wrapped | |
text = text.replace(' ',' ').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> No Differences Found </td>'] | |
tolist = fromlist | |
else: | |
fromlist = tolist = ['<td></td><td> Empty File </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',' ') | |
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() |