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

From: Jakub Narebski <[email-masked]>
Date: Tue, 13 Jan 2009 00:59:19 +0100

Hello!

On Sat, 10 Jan 2009, Johannes Schindelin wrote:
> On Sat, 10 Jan 2009, Jakub Narebski wrote:
>> 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...
> 
> Umm.
> 
> It _is_ Myers' algorithm.  It just so happens that libxdiff hardcodes 
> newline to be the separator.

So amd I to understand that _exported_ functions hardcode separator
to be newline (most probably for performance), and there is no function
in libxdiff which calculates LCS, or returns diff for arrays
(sequences)?

-- 
Jakub Narebski
Poland