如何将 python difflib.unified_diff的输出应用到原始字符串上？

Question

所以，使用Python的difflib，我可以生成两个字符串的diff：

foo = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.n Nullam sed orci lobortis lectus bibendum vehicula.n Integer iaculis eros porttitor velit porttitor scelerisque.n Nunc venenatis nibh.'.splitlines()
bar = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.n Mauris placerat, odio ut viverra gravida, elit leo tincidunt nisi, a pellentesque velit arcu id magna.n Integer iaculis eros porttitor velit porttitor scelerisque.n Nunc venenatis nibh.'.splitlines()
diff = difflib.unified_diff(foo, bar, lineterm='')

然后，如果需要，我们可以检查差异：

>>> print 'n'.join(diff)
--- 
+++ 
@@ -1,4 +1,4 @@
 Lorem ipsum dolor sit amet, consectetur adipiscing elit.
- Nullam sed orci lobortis lectus bibendum vehicula.
+ Mauris placerat, odio ut viverra gravida, elit leo tincidunt nisi, a pellentesque velit arcu id magna.
  Integer iaculis eros porttitor velit porttitor scelerisque.
  Nunc venenatis nibh.

这就是我卡住的地方。如何将该差异应用于字符串foo以导致字符串bar？

Answer 1

如果使用 ndiff，则可以使用 restore 恢复原始字符串

>>> diff = difflib.ndiff(foo, bar)
>>> diff = list(diff)
>>> print ''.join(difflib.restore(diff, 2))
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nullam sed orci lobortis lectus bibendum baculo mihi. Integer iaculis eros porttitor velit porttitor scelerisque. Nunc venenatis nibh.
>>> ''.join(difflib.restore(diff, 2))==''.join(bar)
True
>>> ''.join(difflib.restore(diff, 1))==''.join(foo)
True
>>> 

请注意，由于统一差异通常会删除比较等于开头的行，因此几乎不可能恢复到原始字符串。 ndiff 显示所有内容，因此恢复原始内容会很简单。