third_party/stdlib/difflib.py
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_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_replace ( self , a , alo , ahi , 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 ( 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
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
        ?    ^  ^  ^
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 .