蟒蛇difflib字符差異與unifed上下文格式

Question

我需要在unix統一差異樣式顯示每行字符差異。有沒有辦法做到這一點使用difflib？

我可以分別使用difflib.unified_diff和difflib.Differ（）（ndiff）分別獲得「統一差異」和「每行比較字符」，但我怎樣才能組合它們？

這就是我要找：

# 
# This is difflib.unified 
# 
>>> print ''.join(difflib.unified_diff('one\ntwo\nthree\n'.splitlines(1), 'ore\ntree\nemu\n'.splitlines(1), 'old', 'new')) 
--- old 
+++ new 
@@ -1,3 +1,3 @@ 
-one 
-two 
-three 
+ore 
+tree 
+emu 

>>> 

# 
# This is difflib.Differ 
# 
>>> print ''.join(difflib.ndiff('one\ntwo\nthree\n'.splitlines(1), 'ore\ntree\nemu\n'.splitlines(1))), 
- one 
?^
+ ore 
?^
- two 
- three 
? - 
+ tree 
+ emu 
>>> 


# 
# I want the merge of above two, something like this... 
# 
>>> print ''.join(unified_with_ndiff('one\ntwo\nthree\n'.splitlines(1), 'ore\ntree\nemu\n'.splitlines(1))), 
--- old 
+++ new 
@@ -1,3 +1,3 @@ 
- one 
?^
+ ore 
?^
- two 
- three 
? - 
+ tree 
+ emu 

>>> 

Answer 1

發現我自己的答案挖掘到difflib的源代碼後。

''' 
# mydifflib.py 
@author: Amit Barik 
@summary: Overrides difflib.Differ to present the user with unified format (for Python 2.7). 

Its basically merging of difflib.unified_diff() and difflib.Differ.compare() 
''' 

from difflib import SequenceMatcher 
from difflib import Differ 

class UnifiedDiffer(Differ): 
    def unified_diff(self, a, b, fromfile='', tofile='', fromfiledate='', 
       tofiledate='', n=3, lineterm='\n'): 
     r""" 
     Compare two sequences of lines; generate the resulting delta, in unified 
     format 

     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().unified_diff('one\ntwo\nthree\n'.splitlines(1), 
     ...        'ore\ntree\nemu\n'.splitlines(1)), 
     ...        'old.txt', 'new.txt', 'old-date', 'new-date'), 
     --- old.txt old-date 
     +++ new.txt new-date 
     @@ -1,5 +1,5 @@ 
      context1 
     - one 
     ?^
     + ore 
     ?^
     - two 
     - three 
     ? - 
     + tree 
     + emu 
      context2 
     """ 

     started = False 
     for group in SequenceMatcher(None,a,b).get_grouped_opcodes(n): 
      if not started: 
       fromdate = '\t%s' % fromfiledate if fromfiledate else '' 
       todate = '\t%s' % tofiledate if tofiledate else '' 
       yield '--- %s%s%s' % (fromfile, fromdate, lineterm) 
       yield '+++ %s%s%s' % (tofile, todate, lineterm) 
       started = True 
      i1, i2, j1, j2 = group[0][1], group[-1][2], group[0][3], group[-1][4] 
      yield "@@ -%d,%d +%d,%d @@%s" % (i1+1, i2-i1, j1+1, j2-j1, lineterm) 
      for tag, i1, i2, j1, j2 in group: 
       if tag == 'replace': 
        for line in a[i1:i2]: 
         g = self._fancy_replace(a, i1, i2, b, j1, j2) 
       elif tag == 'equal': 
        for line in a[i1:i2]: 
         g = self._dump(' ', a, i1, i2) 
        if n > 0: 
         for line in g: 
          yield line 
        continue 
       elif tag == 'delete': 
        for line in a[i1:i2]: 
         g = self._dump('-', a, i1, i2) 
       elif tag == 'insert': 
        for line in b[j1:j2]: 
         g = self._dump('+', b, j1, j2) 
       else: 
        raise ValueError, 'unknown tag %r' % (tag,) 

       for line in g: 
        yield line 


def main(): 
    # Test 
    a ='context1\none\ntwo\nthree\ncontext2\n'.splitlines(1) 
    b = 'context1\nore\ntree\nemu\ncontext2\n'.splitlines(1) 
    x = UnifiedDiffer().unified_diff(a, b, 'old.txt', 'new.txt', 'old-date', 'new-date', n=1) 
    print ''.join(x) 

if __name__ == '__main__':   
    main()