diff options
Diffstat (limited to 'Lib/difflib.py')
| -rw-r--r-- | Lib/difflib.py | 100 |
1 files changed, 47 insertions, 53 deletions
diff --git a/Lib/difflib.py b/Lib/difflib.py index a41d4d5..8493503 100644 --- a/Lib/difflib.py +++ b/Lib/difflib.py @@ -1,5 +1,7 @@ #! /usr/bin/env python +from __future__ import generators + """ Module difflib -- helpers for computing deltas between objects. @@ -22,8 +24,6 @@ Class Differ: __all__ = ['get_close_matches', 'ndiff', 'restore', 'SequenceMatcher', 'Differ'] -TRACE = 0 - class SequenceMatcher: """ @@ -406,9 +406,6 @@ class SequenceMatcher: 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 def get_matching_blocks(self): @@ -432,8 +429,6 @@ class SequenceMatcher: 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 @@ -694,7 +689,7 @@ class Differ: Finally, we compare the two: - >>> result = d.compare(text1, text2) + >>> result = list(d.compare(text1, text2)) 'result' is a list of strings, so let's pretty-print it: @@ -731,7 +726,7 @@ class Differ: Construct a text differencer, with optional filters. compare(a, b) - Compare two sequences of lines; return the resulting delta (list). + Compare two sequences of lines; generate the resulting delta. """ def __init__(self, linejunk=None, charjunk=None): @@ -753,16 +748,15 @@ class Differ: self.linejunk = linejunk self.charjunk = charjunk - self.results = [] def compare(self, a, b): r""" - Compare two sequences of lines; return the resulting delta (list). + 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 list returned is also made up of - newline-terminated strings, ready to be used with the `writelines()` + 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: @@ -783,34 +777,38 @@ class Differ: cruncher = SequenceMatcher(self.linejunk, a, b) for tag, alo, ahi, blo, bhi in cruncher.get_opcodes(): if tag == 'replace': - self._fancy_replace(a, alo, ahi, b, blo, bhi) + g = self._fancy_replace(a, alo, ahi, b, blo, bhi) elif tag == 'delete': - self._dump('-', a, alo, ahi) + g = self._dump('-', a, alo, ahi) elif tag == 'insert': - self._dump('+', b, blo, bhi) + g = self._dump('+', b, blo, bhi) elif tag == 'equal': - self._dump(' ', a, alo, ahi) + g = self._dump(' ', a, alo, ahi) else: raise ValueError, 'unknown tag ' + `tag` - results = self.results - self.results = [] - return results + + for line in g: + yield line def _dump(self, tag, x, lo, hi): - """Store comparison results for a same-tagged range.""" + """Generate comparison results for a same-tagged range.""" for i in xrange(lo, hi): - self.results.append('%s %s' % (tag, x[i])) + 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: - self._dump('+', b, blo, bhi) - self._dump('-', a, alo, ahi) + first = self._dump('+', b, blo, bhi) + second = self._dump('-', a, alo, ahi) else: - self._dump('-', a, alo, ahi) - self._dump('+', b, blo, bhi) + 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""" @@ -830,12 +828,6 @@ class Differ: ? ^ ^ ^ """ - if TRACE: - self.results.append('*** _fancy_replace %s %s %s %s\n' - % (alo, ahi, blo, bhi)) - self._dump('>', a, alo, ahi) - self._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 @@ -869,7 +861,8 @@ class Differ: # no non-identical "pretty close" pair if eqi is None: # no identical pair either -- treat it as a straight replace - self._plain_replace(a, alo, ahi, b, blo, bhi) + 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 @@ -879,14 +872,10 @@ class Differ: # a[best_i] very similar to b[best_j]; eqi is None iff they're not # identical - if TRACE: - self.results.append('*** best_ratio %s %s %s %s\n' - % (best_ratio, best_i, best_j)) - self._dump('>', a, best_i, best_i+1) - self._dump('<', b, best_j, best_j+1) # pump out diffs from before the synch point - self._fancy_helper(a, alo, best_i, b, blo, best_j) + 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] @@ -908,22 +897,28 @@ class Differ: btags += ' ' * lb else: raise ValueError, 'unknown tag ' + `tag` - self._qformat(aelt, belt, atags, btags) + for line in self._qformat(aelt, belt, atags, btags): + yield line else: # the synch pair is identical - self.results.append(' ' + aelt) + yield ' ' + aelt # pump out diffs from after the synch point - self._fancy_helper(a, best_i+1, ahi, b, best_j+1, bhi) + 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: - self._fancy_replace(a, alo, ahi, b, blo, bhi) + g = self._fancy_replace(a, alo, ahi, b, blo, bhi) else: - self._dump('-', a, alo, ahi) + g = self._dump('-', a, alo, ahi) elif blo < bhi: - self._dump('+', b, blo, bhi) + g = self._dump('+', b, blo, bhi) + + for line in g: + yield line def _qformat(self, aline, bline, atags, btags): r""" @@ -949,13 +944,13 @@ class Differ: atags = atags[common:].rstrip() btags = btags[common:].rstrip() - self.results.append("- " + aline) + yield "- " + aline if atags: - self.results.append("? %s%s\n" % ("\t" * common, atags)) + yield "? %s%s\n" % ("\t" * common, atags) - self.results.append("+ " + bline) + yield "+ " + bline if btags: - self.results.append("? %s%s\n" % ("\t" * common, 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: @@ -1050,7 +1045,7 @@ def ndiff(a, b, linejunk=IS_LINE_JUNK, charjunk=IS_CHARACTER_JUNK): def restore(delta, which): r""" - Return one of the two sequences that generated a delta. + 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 @@ -1060,6 +1055,7 @@ def restore(delta, which): >>> diff = ndiff('one\ntwo\nthree\n'.splitlines(1), ... 'ore\ntree\nemu\n'.splitlines(1)) + >>> diff = list(diff) >>> print ''.join(restore(diff, 1)), one two @@ -1075,11 +1071,9 @@ def restore(delta, which): raise ValueError, ('unknown delta choice (must be 1 or 2): %r' % which) prefixes = (" ", tag) - results = [] for line in delta: if line[:2] in prefixes: - results.append(line[2:]) - return results + yield line[2:] def _test(): import doctest, difflib |