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Diffstat (limited to 'Tools/scripts/ndiff.py')
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diff --git a/Tools/scripts/ndiff.py b/Tools/scripts/ndiff.py new file mode 100755 index 0000000..2ba5e53 --- /dev/null +++ b/Tools/scripts/ndiff.py @@ -0,0 +1,667 @@ +#! /usr/bin/env python + +# Released to the public domain $JustDate: 3/16/98 $, +# by Tim Peters (email tim_one@email.msn.com). + +# ndiff file1 file2 -- a human-friendly file differencer. + +# $Revision$ +# $NoKeywords: $ + +# SequenceMatcher tries to compute a "human-friendly diff" between +# two sequences (chiefly picturing a file as a sequence of lines, +# and a line as a sequence of characters, here). Unlike UNIX(tm) diff, +# e.g., 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>. +# +# Note that ndiff 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. +# +# With respect to junk, an earlier verion 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 continguous 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 " volative" +# was inserted after "private". I can live with that <wink>. +# +# NOTE on the output: From an ndiff report, +# 1) The first file can be recovered by retaining only lines that begin +# with " " or "- ", and deleting those 2-character prefixes. +# 2) The second file can be recovered similarly, but by retaining only +# " " and "+ " lines. +# 3) Lines beginning with "? " attempt to guide the eye to intraline +# differences, and were not present in either input file. +# +# NOTE on junk: the module-level names +# IS_LINE_JUNK +# IS_CHARACTER_JUNK +# can be set to any functions you like. The first one should accept +# a single string argument, and return true iff the string is junk. +# The default is whether the regexp r"\s*#?\s*$" matches (i.e., a +# line without visible characters, except for at most one splat). +# The second should accept a string of length 1 etc. The default is +# whether the character is a blank or tab (note: bad idea to include +# newline in this!). +# +# After setting those, you can call fcompare(f1name, f2name) with the +# names of the files you want to compare. The difference report +# is sent to stdout. Or you can call main(), which expects to find +# (exactly) the two file names in sys.argv. + +import string +TRACE = 0 + +# define what "junk" means +import re + +def IS_LINE_JUNK(line, pat=re.compile(r"\s*#?\s*$").match): + return pat(line) is not None + +def IS_CHARACTER_JUNK(ch, ws=" \t"): + return ch in ws + +del re + +class SequenceMatcher: + def __init__(self, isjunk=None, a='', b=''): + # 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 + # b2jhas + # b2j.has_key + # 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 has_key method of a hidden dict. + # DOES NOT WORK for x in a! + + self.isjunk = isjunk + self.a = self.b = None + self.set_seqs(a, b) + + def set_seqs(self, a, b): + self.set_seq1(a) + self.set_seq2(b) + + def set_seq1(self, a): + if a is self.a: + return + self.a = a + self.matching_blocks = self.opcodes = None + + def set_seq2(self, b): + 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 ... + # 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 = {} + self.b2jhas = b2jhas = b2j.has_key + for i in xrange(0, len(b)): + elt = b[i] + if b2jhas(elt): + b2j[elt].append(i) + else: + b2j[elt] = [i] + + # Now b2j.keys() contains elements uniquely, and especially when + # the sequence is a string, that's usually a good deal smaller + # than len(string). The difference is the number of isjunk calls + # saved. + isjunk, junkdict = self.isjunk, {} + if isjunk: + for elt in b2j.keys(): + if isjunk(elt): + junkdict[elt] = 1 # value irrelevant; it's a set + del b2j[elt] + + # Now for x in b, isjunk(x) == junkdict.has_key(x), but the + # latter is much faster. Note too that while there may be a + # lot of junk in the sequence, the number of *unique* junk + # elements is probably small. So the memory burden of keeping + # this dict alive is likely trivial compared to the size of b2j. + self.isbjunk = junkdict.has_key + + 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, returns one + that starts earliest in a, and of all those maximal matching + blocks that start earliest in a, returns the one that starts + earliest in b. + + 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. + + If no blocks match, returns (alo, blo, 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. + + # find longest junk-free match + a, b, b2j, isbjunk = self.a, self.b, self.b2j, self.isbjunk + besti, bestj, bestsize = alo, blo, 0 + for i in xrange(alo, ahi): + # check for longest match starting at a[i] + if i + bestsize >= ahi: + # we're too far right to get a new best + break + # 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 + for j in b2j.get(a[i], []): + # a[i] matches b[j] + if j < blo: + continue + if j + bestsize >= bhi: + # we're too far right to get a new best, here or + # anywhere to the right + break + if a[i + bestsize] != b[j + bestsize]: + # can't be longer match; this test is not necessary + # for correctness, but is a huge win for efficiency + continue + # set k to length of match + k = 1 # a[i] == b[j] already known + while i + k < ahi and j + k < bhi and \ + a[i+k] == b[j+k] and not isbjunk(b[j+k]): + k = k + 1 + if k > bestsize: + besti, bestj, bestsize = i, j, k + if i + bestsize >= ahi: + # only time in my life I really wanted a + # labelled break <wink> -- we're done with + # both loops now + break + + # 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 + + if TRACE: + print "get_matching_blocks", alo, ahi, blo, bhi + print " returns", besti, bestj, bestsize + return besti, bestj, bestsize + +# A different implementation, using a binary doubling technique that +# does far fewer element compares (trades 'em for integer compares), +# and has n*lg n worst-case behavior. Alas, the code is much harder +# to follow (the details are tricky!), and in most cases I've seen, +# it takes at least 50% longer than the "clever dumb" method above; +# probably due to creating layers of small dicts. +# NOTE: this no longer matches the version above wrt junk; remains +# too unpromising to update it; someday, though ... + +# def find_longest_match(self, alo, ahi, blo, bhi): +# """Find longest matching block in a[alo:ahi] and b[blo:bhi]. +# +# 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, returns one +# that starts earliest in a, and of all those maximal matching +# blocks that start earliest in a, returns the one that starts +# earliest in b. +# +# If no blocks match, returns (alo, blo, 0). +# """ +# +# a, b2j = self.a, self.b2j +# # alljs[size][i] is a set of all j's s.t. a[i:i+len] matches +# # b[j:j+len] +# alljs = {} +# alljs[1] = js = {} +# ahits = {} +# for i in xrange(alo, ahi): +# elt = a[i] +# if ahits.has_key(elt): +# js[i] = ahits[elt] +# continue +# if b2j.has_key(elt): +# in_range = {} +# for j in b2j[elt]: +# if j >= blo: +# if j >= bhi: +# break +# in_range[j] = 1 +# if in_range: +# ahits[elt] = js[i] = in_range +# del ahits +# size = 1 +# while js: +# oldsize = size +# size = size + size +# oldjs = js +# alljs[size] = js = {} +# for i in oldjs.keys(): +# # i has matches of size oldsize +# if not oldjs.has_key(i + oldsize): +# # can't double it +# continue +# second_js = oldjs[i + oldsize] +# answer = {} +# for j in oldjs[i].keys(): +# if second_js.has_key(j + oldsize): +# answer[j] = 1 +# if answer: +# js[i] = answer +# del alljs[size] +# size = size >> 1 # max power of 2 with a match +# if not size: +# return alo, blo, 0 +# besti, bestj, bestsize = alo, blo, 0 +# fatis = alljs[size].keys() +# fatis.sort() +# for i in fatis: +# # figure out longest match starting at a[i] +# totalsize = halfsize = size +# # i has matches of len totalsize at the indices in js +# js = alljs[size][i].keys() +# while halfsize > 1: +# halfsize = halfsize >> 1 +# # is there a match of len halfsize starting at +# # i + totalsize? +# newjs = [] +# if alljs[halfsize].has_key(i + totalsize): +# second_js = alljs[halfsize][i + totalsize] +# for j in js: +# if second_js.has_key(j + totalsize): +# newjs.append(j) +# if newjs: +# totalsize = totalsize + halfsize +# js = newjs +# if totalsize > bestsize: +# besti, bestj, bestsize = i, min(js), totalsize +# return besti, bestj, bestsize + + def get_matching_blocks(self): + if self.matching_blocks is not None: + return self.matching_blocks + self.matching_blocks = [] + la, lb = len(self.a), len(self.b) + self.__helper(0, la, 0, lb, self.matching_blocks) + self.matching_blocks.append( (la, lb, 0) ) + if TRACE: + print '*** matching blocks', self.matching_blocks + return self.matching_blocks + + # builds list of matching blocks covering a[alo:ahi] and + # b[blo:bhi], appending them in increasing order to answer + + def __helper(self, alo, ahi, blo, bhi, answer): + 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 alo < i and blo < j: + self.__helper(alo, i, blo, j, answer) + answer.append( x ) + if i+k < ahi and j+k < bhi: + self.__helper(i+k, ahi, j+k, bhi, answer) + + 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*M / T. + Note that this is 1 if the sequences are identical, and 0 if + they have nothing in common. + """ + + matches = reduce(lambda sum, triple: sum + triple[-1], + self.get_matching_blocks(), 0) + return 2.0 * matches / (len(self.a) + len(self.b)) + + def quick_ratio(self): + """Return an upper bound on ratio() relatively quickly.""" + # 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.has_key, 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 2.0 * matches / (len(self.a) + len(self.b)) + + def real_quick_ratio(self): + """Return an upper bound on ratio() very quickly""" + la, lb = len(self.a), len(self.b) + # can't have more matches than the number of elements in the + # shorter sequence + return 2.0 * min(la, lb) / (la + lb) + + def get_opcodes(self): + 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 + +# meant for dumping lines +def dump(tag, x, lo, hi): + for i in xrange(lo, hi): + print tag, x[i], + +# figure out which mark to stick under characters in lines that +# have changed (blank = same, - = deleted, + = inserted, ^ = replaced) +_combine = { ' ': ' ', + '. ': '-', + ' .': '+', + '..': '^' } + +def plain_replace(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: + dump('+', b, blo, bhi) + dump('-', a, alo, ahi) + else: + dump('-', a, alo, ahi) + dump('+', b, blo, bhi) + +# When replacing one block of lines with another, this guy searches +# 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. + +def fancy_replace(a, alo, ahi, b, blo, bhi): + if TRACE: + print '*** fancy_replace', alo, ahi, blo, bhi + dump('>', a, alo, ahi) + dump('<', b, blo, bhi) + + # 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(IS_CHARACTER_JUNK) + 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 + plain_replace(a, alo, ahi, b, blo, bhi) + 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 + if TRACE: + print '*** best_ratio', best_ratio, best_i, best_j + dump('>', a, best_i, best_i+1) + dump('<', b, best_j, best_j+1) + + # pump out diffs from before the synch point + fancy_helper(a, alo, best_i, b, blo, best_j) + + # do intraline marking on the synch pair + aelt, belt = a[best_i], b[best_j] + if eqi is None: + # pump out a '-', '+', '?' triple 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 = atags + '.' * la + btags = btags + '.' * lb + elif tag == 'delete': + atags = atags + '.' * la + elif tag == 'insert': + btags = btags + '.' * lb + elif tag == 'equal': + atags = atags + ' ' * la + btags = btags + ' ' * lb + else: + raise ValueError, 'unknown tag ' + `tag` + la, lb = len(atags), len(btags) + if la < lb: + atags = atags + ' ' * (lb - la) + elif lb < la: + btags = btags + ' ' * (la - lb) + combined = map(lambda x,y: _combine[x+y], atags, btags) + print '-', aelt, '+', belt, '?', \ + string.rstrip(string.join(combined, '')) + else: + # the synch pair is identical + print ' ', aelt, + + # pump out diffs from after the synch point + fancy_helper(a, best_i+1, ahi, b, best_j+1, bhi) + +def fancy_helper(a, alo, ahi, b, blo, bhi): + if alo < ahi: + if blo < bhi: + fancy_replace(a, alo, ahi, b, blo, bhi) + else: + dump('-', a, alo, ahi) + elif blo < bhi: + dump('+', b, blo, bhi) + +# open a file & return the file object; gripe and return 0 if it +# couldn't be opened +def fopen(fname): + try: + return open(fname, 'r') + except IOError, detail: + print "couldn't open " + fname + ": " + `detail` + return 0 + +# open two files & spray the diff to stdout; return false iff a problem +def fcompare(f1name, f2name): + f1 = fopen(f1name) + f2 = fopen(f2name) + if not f1 or not f2: + return 0 + + a = f1.readlines(); f1.close() + b = f2.readlines(); f2.close() + + cruncher = SequenceMatcher(IS_LINE_JUNK, a, b) + for tag, alo, ahi, blo, bhi in cruncher.get_opcodes(): + if tag == 'replace': + fancy_replace(a, alo, ahi, b, blo, bhi) + elif tag == 'delete': + dump('-', a, alo, ahi) + elif tag == 'insert': + dump('+', b, blo, bhi) + elif tag == 'equal': + dump(' ', a, alo, ahi) + else: + raise ValueError, 'unknown tag ' + `tag` + + return 1 + +# get file names from argv & compare; return false iff a problem +def main(): + from sys import argv + if len(argv) != 3: + print 'need 2 args' + return 0 + [f1name, f2name] = argv[1:3] + print '-:', f1name + print '+:', f2name + return fcompare(f1name, f2name) + +if __name__ == '__main__': + if 1: + main() + else: + import profile, pstats + statf = "ndiff.pro" + profile.run("main()", statf) + stats = pstats.Stats(statf) + stats.strip_dirs().sort_stats('time').print_stats() + |