appy.shared.diff: more flesh on the XhtmlDiff class.
This commit is contained in:
Gaetan Delannay
parent
c11378c747
commit
1ebcbb7b34
356
shared/diff.py
356
shared/diff.py
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@ -1,5 +1,104 @@
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# ------------------------------------------------------------------------------
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import difflib
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import re, difflib
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# ------------------------------------------------------------------------------
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innerDiff = re.compile('<span name="(insert|delete)".*?>(.*?)</span>')
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# ------------------------------------------------------------------------------
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class Merger:
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'''This class allows to merge 2 lines of text, each containing inserts and
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deletions.'''
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def __init__(self, lineA, lineB, previousDiffs):
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# lineA comes "naked": any diff previously found on it was removed from
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# it (ie, deleted text has been completely removed, while inserted text
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# has been included, but without its surrounding tag). Info about
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# previous diffs is kept in a separate variable "previousDiffs".
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self.lineA = lineA
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self.previousDiffs = previousDiffs
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# Differences between lineA and lineB have just been computed and are
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# included (within inner tags) in lineB. We will compute their position
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# in self.newDiffs (see below).
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self.lineB = lineB
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self.newDiffs = self.computeNewDiffs()
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# We choose to walk within self.lineB. We will keep in self.i our
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# current position within self.lineB.
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self.i = 0
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# The delta index that must be applied on previous diffs
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self.deltaPrevious = 0
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def computeNewDiffs(self):
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'''lineB may include inner "insert" and/or tags. This function
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detects them.'''
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i = 0
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res = []
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while i < len(self.lineB):
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match = innerDiff.search(self.lineB, i)
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if not match: break
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res.append(match)
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i = match.end()
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return res
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def getNextDiff(self):
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'''During the merging process on self.lineB, what next diff to
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"consume"? An old one? A new one?'''
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# No more diff ?
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if not self.previousDiffs and not self.newDiffs:
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return None, None, None
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# No more new diff ?
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if not self.newDiffs:
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diff = self.previousDiffs[0]
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del self.previousDiffs[0]
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return diff, diff.start() + self.deltaPrevious, True
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# No more previous diff ?
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if not self.previousDiffs:
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diff = self.newDiffs[0]
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del self.newDiffs[0]
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return diff, diff.start(), False
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# At least one more new and previous diff. Which one to consume?
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previousDiff = self.previousDiffs[0]
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newDiff = self.newDiffs[0]
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previousDiffIndex = previousDiff.start() + self.deltaPrevious
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newDiffIndex = newDiff.start()
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if previousDiffIndex <= newDiffIndex:
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# Previous wins
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del self.previousDiffs[0]
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return previousDiff, previousDiffIndex, True
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else:
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# New wins
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del self.newDiffs[0]
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return newDiff, newDiffIndex, False
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def merge(self):
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'''Merges self.previousDiffs into self.lineB.'''
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res = ''
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diff, diffStart, isPrevious = self.getNextDiff()
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while diff:
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# Dump the part of lineB between self.i and diffStart
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res += self.lineB[self.i:diffStart]
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self.i = diffStart
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# Dump the diff
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res += diff.group(0)
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if isPrevious:
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if diff.group(1) == 'insert':
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self.i += len(diff.group(2))
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else:
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# Update self.i
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self.i += len(diff.group(0))
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# Because of this new diff, all indexes computed on lineA are
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# now wrong because we express them relative to lineB. So:
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# update self.deltaPrevious to take this into account.
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self.deltaPrevious += len(diff.group(0))
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if diff.group(1) == 'delete':
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# The indexes in lineA do not take the deleted text into
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# account, because it wasn't deleted at this time. So remove
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# from self.deltaPrevious the length of removed text.
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self.deltaPrevious -= len(diff.group(2))
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# Load next diff
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diff, diffStart, isPrevious = self.getNextDiff()
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# Dump the end of self.lineB if not completely consumed
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if self.i < len(self.lineB):
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res += self.lineB[self.i:]
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return res
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# ------------------------------------------------------------------------------
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class HtmlDiff:
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@ -10,7 +109,8 @@ class HtmlDiff:
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def __init__(self, old, new,
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insertMsg='Inserted text', deleteMsg='Deleted text',
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insertCss=None, deleteCss=None, diffRatio=0.7):
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insertCss=None, deleteCss=None, insertName='insert',
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deleteName='delete', diffRatio=0.7):
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# p_old and p_new are strings containing chunks of HTML.
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self.old = old.strip()
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self.new = new.strip()
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@ -26,18 +126,30 @@ class HtmlDiff:
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# be used (see HtmlDiff.insertStyle and HtmlDiff.deleteStyle).
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self.insertCss = insertCss
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self.deleteCss = deleteCss
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# This tag will get a "name" attribute whose content will be
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# p_insertName or p_deleteName
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self.insertName = insertName
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self.deleteName = deleteName
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# The diff algorithm of this class will need to identify similarities
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# between strings. Similarity ratios will be computed by using method
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# difflib.SequenceMatcher.ratio (see m_isSimilar below). Strings whose
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# comparison will produce a ratio above p_diffRatio will be considered
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# as similar.
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self.diffRatio = diffRatio
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# Some computed values
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for tag in ('div', 'span'):
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setattr(self, '%sInsertPrefix' % tag,
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'<%s name="%s"' % (tag, self.insertName))
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setattr(self, '%sDeletePrefix' % tag,
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'<%s name="%s"' % (tag, self.deleteName))
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def getModifiedChunk(self, seq, type, sep):
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'''p_sep.join(p_seq) is a chunk that was either inserted
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(p_type='insert') or deleted (p_type='delete'). This method will
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surround this part with a div or span tag that will get some CSS
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class allowing to highlight the difference.'''
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'''p_sep.join(p_seq) (if p_seq is a list) or p_seq (if p_seq is a
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string) is a chunk that was either inserted (p_type='insert') or
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deleted (p_type='delete'). This method will surround this part with
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a div or span tag that will get some CSS class allowing to highlight
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the difference.'''
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# Prepare parts of the surrounding tag.
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if sep == '\n': tag = 'div'
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else: tag = 'span'
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exec 'msg = self.%sMsg' % type
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@ -47,7 +159,22 @@ class HtmlDiff:
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else:
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exec 'style = self.%sStyle' % type
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style = 'style="%s"' % style
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return '<%s %s title="%s">%s</%s>' % (tag,style,msg,sep.join(seq),tag)
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exec 'tagName = self.%sName' % type
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# The idea is: if there are several lines, every line must be surrounded
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# by a tag. this way, we know that a surrounding tag can't span several
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# lines, which is a prerequisite for managing cumulative diffs.
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if sep == ' ':
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seq = sep.join(seq)
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sep = ''
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if isinstance(seq, basestring):
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return '%s<%s name="%s" %s title="%s">%s</%s>%s' % \
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(sep, tag, tagName, style, msg, seq, tag, sep)
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else:
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res = ''
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for line in seq:
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res += '%s<%s name="%s" %s title="%s">%s</%s>%s' % \
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(sep, tag, tagName, style, msg, line, tag, sep)
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return res
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def getStringDiff(self, old, new):
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'''Identifies the differences between strings p_old and p_new by
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@ -62,6 +189,7 @@ class HtmlDiff:
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diffFound = False
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while not diffFound:
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i += 1
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if (i == len(old)) or (i == len(new)): break
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if old[i] != new[i]: diffFound = True
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# Compute jo and jn
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jo = len(old)
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@ -84,110 +212,206 @@ class HtmlDiff:
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ratio = difflib.SequenceMatcher(a=s1.lower(), b=s2.lower()).ratio()
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return ratio > self.diffRatio
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def isEmpty(self, l):
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'''Is list p_l empty ?'''
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return not l or ( (len(l) == 1) and (l[0] in ('', '\r')))
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def getTagContent(self, line):
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'''p_lines is a XHTML tag with content. This method returns the content
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of the tag, removing start and end tags.'''
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return line[line.find('>')+1:line.rfind('<')]
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def getLineAndType(self, line):
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'''p_line is a string that can already have been surrounded by an
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"insert" or "delete" tag. This is what we try to determine here.
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This method returns a tuple (type, line, innerDiffs), where "type"
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can be:
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* "insert" if it has already been flagged as inserted;
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* "delete" if it has already been flagged as deleted;
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* None else;
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"line" holds the original parameter p_line, excepted:
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* if type="insert". In that case, the surrounding insert tag has been
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removed;
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* if inner diff tags (insert or delete) are found. In that case,
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- if inner "insert" tags are found, they are removed but their
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content is kept;
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- if inner "delete" tags are found, they are removed, content
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included;
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- "innerDiffs" holds the list of re.MatchObjects instances
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representing the found inner tags.
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'''
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if line.startswith(self.divDeletePrefix): return ('delete', line, None)
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if line.startswith(self.divInsertPrefix):
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# Return the line without the surrounding tag.
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return ('insert', self.getTagContent(line), None)
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# Replace found inner inserts with their content.
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innerDiffs = []
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while True:
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match = innerDiff.search(line)
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if not match: break
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# I found one.
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innerDiffs.append(match)
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# Keep content only for "insert" tags.
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content = ''
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if match.group(1) == 'insert':
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content = match.group(2)
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line = line[:match.start()] + content + line[match.end():]
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return (None, line, innerDiffs)
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def getSeqDiff(self, seqA, seqB):
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'''p_seqA and p_seqB are lists of strings. Here we will try to identify
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similarities between strings from p_seqA and p_seqB, and return a
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list of differences between p_seqA and p_seqB, where each element
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is a tuple (action, data).
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* If p_action is "delete", data is a sublist of p_seqA with lines
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considered as not included anymore in p_seqB;
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* If p_action is "replace", data is a tuple (lineA, lineB) containing
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one line from p_seqA and one from p_seqB considered as similar;
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* If p_action is "insert", data is a sublist of p_seqB with lines
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considered as not included in p_seqA.
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is a tuple (action, line).
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* If p_action is "delete", "line" is a line of p_seqA considered as
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not included anymore in p_seqB;
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* If p_action is "insert", "line" is a line of p_seqB considered as
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not included in p_seqA;
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* If p_action is "replace", "line" is a tuple
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(lineA, lineB, previousDiffsA) containing one line from p_seqA and
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one from p_seqB considered as similar. "previousDiffsA" contains
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potential previous inner diffs that were found (but extracted
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from, for comparison purposes) lineA.
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'''
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res = []
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i = j = k = 0
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deleted = []
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# Scan every string from p_seqA and try to find a similar string in
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# p_seqB.
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while i < len(seqA):
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if k == len(seqB):
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pastAction, lineSeqA, innerDiffs = self.getLineAndType(seqA[i])
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if pastAction == 'delete':
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# We will consider this line as "equal" because it already has
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# been noted as deleted in a previous diff.
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res.append( ('equal', seqA[i]) )
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elif k == len(seqB):
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# We have already "consumed" every string from p_seqB. Remaining
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# strings from p_seqA must now be considered has having been
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# deleted.
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if deleted: res.append( ('delete', deleted) )
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res.append( ('delete', seqA[i:]) )
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break
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# strings from p_seqA must be considered as deleted (or
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# sometimes equal, see above)
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if not pastAction: res.append( ('delete', seqA[i]) )
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else:
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# 'insert': should not happen. The inserted line should also
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# be found in seqB.
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res.append( ('equal', seqA[i]) )
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else:
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# Try to find a line in seqB which is similar to lineSeqA.
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similarFound = False
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for j in range(k, len(seqB)):
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if self.isSimilar(seqA[i], seqB[j]):
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if self.isSimilar(lineSeqA, seqB[j]):
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similarFound = True
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if deleted:
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# Dump first the strings flagged as deleted.
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res.append( ('delete', deleted) )
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deleted = []
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# Strings between indices k and j in p_seqB must be
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# considered as inserted, because no similar line exists
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# in p_seqA.
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if k < j:
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res.append( ('insert', seqB[k:j]) )
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# Similar strings are appended in a 'replace' entry
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res.append(('replace', (seqA[i], seqB[j])))
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for line in seqB[k:j]: res.append(('insert', line))
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# Similar strings are appended in a 'replace' entry,
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# excepted if lineSeqA is already an insert from a
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# previous diff: in this case, we keep the "old"
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# version: the new one is the same, but for which we
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# don't remember who updated it.
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if (pastAction == 'insert') and (lineSeqA == seqB[j]):
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res.append( ('equal', seqA[i]) )
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# TODO: manage lineSeqA != seqB[j]
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else:
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res.append(('replace', (lineSeqA, seqB[j],
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innerDiffs)))
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k = j+1
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break
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if not similarFound:
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# Add to list of deleted lines.
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deleted.append(seqA[i])
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if not similarFound: res.append( ('delete', seqA[i]) )
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i += 1
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# Consider any "unconsumed" line from p_seqB as being inserted.
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if deleted: res.append( ('delete', deleted) )
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if k < len(seqB): res.append( ('insert', seqB[k:]) )
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if k < len(seqB):
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for line in seqB[k:]: res.append( ('insert', line) )
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return res
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def split(self, s, sep):
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'''Splits string p_s with p_sep. If p_sep is a space, the split can't
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happen for a leading or trailing space, which must be considered as
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being part of the first or last word.'''
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# Manage sep == \n
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if sep == '\n': return s.split(sep)
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leadSpace = s.startswith(sep)
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trailSpace = s.endswith(sep)
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if not leadSpace and not trailSpace: return s.split(sep)
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res = s.strip(sep).split(sep)
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if leadSpace: res[0] = sep + res[0]
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if trailSpace: res[-1] = res[-1] + sep
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return res
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def getHtmlDiff(self, old, new, sep):
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'''Returns the differences between p_old and p_new. Result is a string
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containing the comparison in HTML format. p_sep is used for turning
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p_old and p_new into sequences.'''
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p_old and p_new into sequences. If p_sep is a carriage return, this
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method is used for performing a whole diff between 2 strings splitted
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into sequences of lines; if sep is a space, the diff is a
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word-by-word comparison within 2 lines that have been detected as
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similar in a previous call to m_getHtmlDiff with sep=carriage
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return.'''
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res = []
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a = old.split(sep)
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b = new.split(sep)
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a = self.split(old, sep)
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b = self.split(new, sep)
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matcher = difflib.SequenceMatcher()
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matcher.set_seqs(a,b)
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for action, i1, i2, j1, j2 in matcher.get_opcodes():
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chunkA = a[i1:i2]
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chunkB = b[j1:j2]
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aIsEmpty = self.isEmpty(chunkA)
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bIsEmpty = self.isEmpty(chunkB)
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toAdd = None
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if action == 'equal':
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toAdd = sep.join(a[i1:i2])
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if not aIsEmpty: toAdd = sep.join(chunkA)
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elif action == 'insert':
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print 'INSERT', b[j1:j2]
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toAdd = self.getModifiedChunk(b[j1:j2], action, sep)
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if not bIsEmpty:
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toAdd = self.getModifiedChunk(chunkB, action, sep)
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elif action == 'delete':
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print 'DELETE', a[i1:i2]
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toAdd = self.getModifiedChunk(a[i1:i2], action, sep)
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if not aIsEmpty:
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toAdd = self.getModifiedChunk(chunkA, action, sep)
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elif action == 'replace':
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if sep == '\n':
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print 'REPLACE', a[i1:i2]
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print 'WITH', b[j1:j2]
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# We know that some lines have been replaced from a to b. By
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# identifying similarities between those lines, consider
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# some as having been deleted, modified or inserted.
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if aIsEmpty and bIsEmpty:
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toAdd = ''
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for sAction, data in self.getSeqDiff(a[i1:i2], b[j1:j2]):
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elif aIsEmpty:
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# Was an addition, not a replacement
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toAdd = self.getModifiedChunk(chunkB, 'insert', sep)
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elif bIsEmpty:
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# Was a deletion, not a replacement
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toAdd = self.getModifiedChunk(chunkA, 'delete', sep)
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else: # At least, a true replacement (grr difflib)
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if sep == '\n':
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# We know that some lines have been replaced from a to
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# b. By identifying similarities between those lines,
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# consider some as having been deleted, modified or
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# inserted.
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toAdd = ''
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for sAction, line in self.getSeqDiff(chunkA, chunkB):
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if sAction in ('insert', 'delete'):
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toAdd += self.getModifiedChunk(data, sAction, sep)
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toAdd += self.getModifiedChunk(line,sAction,sep)
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elif sAction == 'equal':
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toAdd += line
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elif sAction == 'replace':
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lineA, lineB = data
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# Investigate further here and explore differences
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# at the *word* level between lineA and lineB. As a
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# preamble, and in order to restrict annoyances due
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# to the presence of XHTML tags, we will compute
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# start and end parts wich are similar between lineA
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# and lineB: they may correspond to opening and
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lineA, lineB, previousDiffsA = line
|
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# Investigate further here and explore
|
||||
# differences at the *word* level between lineA
|
||||
# and lineB. As a preamble, and in order to
|
||||
# restrict annoyances due to the presence of
|
||||
# XHTML tags, we will compute start and end
|
||||
# parts wich are similar between lineA and
|
||||
# lineB: they may correspond to opening and
|
||||
# closing XHTML tags.
|
||||
i, ja, jb = self.getStringDiff(lineA, lineB)
|
||||
diff = self.getHtmlDiff(lineA[i:ja],lineB[i:jb],' ')
|
||||
diff = self.getHtmlDiff(lineA[i:ja],
|
||||
lineB[i:jb], ' ')
|
||||
toAdd += lineB[:i] + diff + lineB[jb:]
|
||||
# Merge potential previous inner diff tags that
|
||||
# were found (but extracted from) lineA.
|
||||
if previousDiffsA:
|
||||
merger= Merger(lineA, toAdd, previousDiffsA)
|
||||
toAdd = merger.merge()
|
||||
else:
|
||||
if ((i2-i1) == 1) and (a[i1] == ''):
|
||||
# difflib has considered an empty char as 'removed' (?)
|
||||
toAdd = ''
|
||||
else:
|
||||
toAdd = self.getModifiedChunk(a[i1:i2],'delete', sep)
|
||||
toAdd += self.getModifiedChunk(b[j1:j2],'insert', sep)
|
||||
res.append(toAdd)
|
||||
toAdd = self.getModifiedChunk(chunkA, 'delete', sep)
|
||||
toAdd += self.getModifiedChunk(chunkB, 'insert', sep)
|
||||
if toAdd: res.append(toAdd)
|
||||
return sep.join(res)
|
||||
|
||||
def get(self):
|
||||
'''Produces the result.'''
|
||||
print 'RUN'
|
||||
return self.getHtmlDiff(self.old, self.new, '\n')
|
||||
# ------------------------------------------------------------------------------
|
||||
|
|
|
|||
Loading…
Reference in a new issue