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Re: [PATCH v2] make diff --color-words customizable

From
DLDavide Libenzi <davidel@xmailserver.org>
Date
Jan 10, 2009, 17:53 UTC
Message-ID
<alpine.DEB.1.10.0901100950230.21891@alien.or.mcafeemobile.com>
In-Reply-To
<200901101436.48149.jnareb@gmail.com>
On Sat, 10 Jan 2009, Jakub Narebski wrote:
Show 19 quoted lines
> On Sat, 10 Jan 2009, Johannes Schindelin wrote:
> > On Sat, 10 Jan 2009, Jakub Narebski wrote:
> > > Thomas Rast wrote:
> > > 
> > > > --color-words works (and always worked) by splitting words onto one
> > > > line each, and using the normal line-diff machinery to get a word
> > > > diff. 
> > > 
> > > Cannot we generalize diff machinery / use underlying LCS diff engine
> > > instead of going through line diff?
> > 
> > What do you think we're doing?  libxdiff is pretty hardcoded to newlines.  
> > That's why we're substituting non-word characters with newlines.
> 
> Isn't Meyers algorithm used by libxdiff based on LCS, largest common
> subsequence, and doesn't it generate from the mathematical point of
> view "diff" between two sequences (two arrays) which just happen to
> be lines? It is a bit strange that libxdiff doesn't export its low
> level algorithm...

The core doesn't know anything about lines. Only pre-processing (setting up the hash by tokenizing the input) and post-processing (adding '\n' to the end of each token), knows about newlines. Memory consumption would increase significantly though, since there is a per-token cost, and a word-based diff will create more of them WRT the same input.

- Davide
Previous: Johannes SchindelinNext: Jakub Narebski
Message 15 of 34 in “make diff --color-words customizable”
  1. make diff --color-words customizableThomas Rast, Jan 9, 2009
  2. Johannes SchindelinJan 9, 2009
  3. Thomas RastJan 9, 2009
  4. Johannes SchindelinJan 9, 2009
  5. color-words: take an optional regular expression describing wordsJohannes Schindelin, Jan 9, 2009
  6. Thomas RastJan 9, 2009
  7. Teemu LikonenJan 9, 2009
  8. make diff --color-words customizableThomas Rast, Jan 10, 2009
  9. Jakub NarebskiJan 10, 2009
  10. Johannes SchindelinJan 10, 2009
  11. Jakub NarebskiJan 10, 2009
  12. Johannes SchindelinJan 10, 2009
  13. Jakub NarebskiJan 12, 2009
  14. Johannes SchindelinJan 13, 2009
  15. Davide LibenziJan 10, 2009
  16. Jakub NarebskiJan 13, 2009
  17. Davide LibenziJan 13, 2009
  18. Johannes SchindelinJan 10, 2009
  19. Thomas RastJan 10, 2009
  20. Johannes SchindelinJan 10, 2009
  21. Junio C HamanoJan 11, 2009
  22. 0/4 customizable --color-wordsThomas Rast, Jan 11, 2009
  23. 1/4 word diff: comments, preparations for regex customizationThomas Rast, Jan 11, 2009
  24. 2/4 word diff: customizable word splitsThomas Rast, Jan 11, 2009
  25. 3/4 word diff: make regex configurable via attributesThomas Rast, Jan 11, 2009
  26. 4/4 word diff: test customizable word splitsThomas Rast, Jan 11, 2009
  27. Junio C HamanoJan 11, 2009
  28. Junio C HamanoJan 11, 2009
  29. Johannes SchindelinJan 11, 2009
  30. Johannes SchindelinJan 11, 2009
  31. Junio C HamanoJan 11, 2009
  32. Jeff KingJan 9, 2009
  33. Johannes SchindelinJan 9, 2009
  34. Jeff KingJan 9, 2009

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