Re: Fwd: possible Improving diff algoritm

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 12, 2012, 21:53 UTC
Message-ID: <7vpq2f2az4.fsf@alter.siamese.dyndns.org>
In-Reply-To: <CANv4PNm45xGBn2veKi1o0wB4K9NgsbtCsiymHNO4xbCDpJ5tDg@mail.gmail.com>

Morten Welinder <mwelinder@gmail.com> writes:

> Is there a reason why picking among the choices in a sliding window
> must be contents neutral?

Sorry, you might be getting at something interesting but I do not understand the question. I have no idea what you mean by "contents neutral".

Picking between these two choices

         /**                         +    /**                         
    +     * Default parent           +     * Default parent           
    +     *                          +     *                          
    +     * @var int                 +     * @var int                 
    +     * @access protected        +     * @access protected        
    +     * @index                   +     * @index                   
    +     */                         +     */                         
    +    protected $defaultParent;   +    protected $defaultParent;   
    +                                +                                
    +    /**                              /**

would not affect the correctness of the patch. You may pick whatever you deem the most desirable, but your answer must be a correct patch (the definition of "correct" here is "applying that patch to the preimage produces the intended postimage").

And I think if you inserted a block of text B after a context C where the tail of B matches the tail of C like the above, you can shift what you treat as "inserted" up and still come up with a correct patch.

The output being "a correct patch" is not the only thing we need to consider, though, as I mentioned in another response to Kevin regarding the "consequences".