[sword-devel] osis2mod linking bug

[DM Smith]

Greg Hellings wrote:
> DM,
>
> On Thu, Sep 4, 2008 at 1:05 PM, DM Smith <dmsmith555 at yahoo.com> wrote:
>   
>> I'm trying to solve an osis2mod linking bug that was exposed by several
>> beta modules.
>>
>> Here is the scenario:
>> <verse osisID="XXX.1.29 XXX.1.30 XXX.1.31">Text for the last three
>> verses of XXX, chapter 1 in the KJV versification</verse>
>> <verse osisID="XXX.1.32 XXX.1.33">Text for additional verses in the XXX,
>> chapter 1 in the non-KJV versification</verse>
>>
>> 1) osis2mod links 1.30 and 1.31 by writing out the start and offset of
>> the data for 1.29. That means that 1.29 has to be written first. In the
>> index file the result is that all three entries have the same start and
>> offset. So far so good, if there weren't a bug that writes the links
>> first and then the data, resulting in start/offset of 0/0 for the links.
>> But I've already figured out how to fix that bug.
>>
>> 2) Now a non-KJV verse is found and osis2mod appends it to the last
>> verse of the chapter according to the KJV versification. So the entry
>> for XXX.1.31 is found, the raw text is gotten and it is appended and
>> this augmented text is written to the data file, at the end of the file.
>> Finally the index entry for XXX.1.31 is updated.
>>
>> The problem is that 1.29 and 1.30 are not updated, they still point to
>> the "1.29-1.31" text and now 1.31 points to the "1.29-1.33" text.
>>
>> 3) The other problem is with 1.33, it is noticed that it is out of
>> bounds and is changed to 1.31 and then it is linked to 1.32, which does
>> not exist and thus 1.31 is re-written to 0/0.
>>
>> I'm looking for a way to solve these problems. Here is what I am
>> thinking and I'd like feedback or a better way.
>> For 1) I have postponed the writing of the links until the verse is
>> written. I could either wait until the next verse is ready to be
>> written, or later. I've decided to wait until the very end and do the
>> linking then. This might help solve 2 and 3.
>>
>> For 2) I'm thinking that the verse to append is the last verse in the
>> chapter with content. By postponing linking until later, it will append
>> to 1.29. Then the linking will propagate the final start/offset values
>> for 1.29. The problem I have with this is that this is somewhat disk
>> intensive. I start with the last verse in the chapter and get the raw
>> text for it. If there is none, I then decrement and refetch until I find
>> it. I looked for a way to know if a verse were part of a linked set and
>> what the members of that set were, but I didn't see any in the SWORD
>> engine. Am I missing it?
>>     
>
> When I ran into this bug in dabbling with a SWORD front-end, I was
> told that the only way to test for whether it is part of a set is to
> compare the text of verse x with verse x-1.  I don't know that the
> feature we both sought has been added.  If it has, I haven not heard
> word of it.
>   
Ouch, that is expensive. It should not be necessary to dig down to the 
text and then do a string comparison. Comparing the start/offset 
(block/start/offset for compressed) is sufficient. I don't see how to 
get this info. It would be nice to have the ability, in the engine, to 
compare two keys to see if they refer to the same text.

> Alternatively -- aren't we supposed to be moving to the VerseTreeKey?
> Shouldn't a new module in the Beta stage be using that?  It seems like
> that would completely do away with the problem.  Updating osis2mod to
> use that, either as the default or as an option for a module like this
> might eliminate the issue?
>   
I think ultimately that osis2mod will need to be updated to handle other 
versifications. The VerseKey module type is significantly faster than a 
VerseTreeKey module will ever be.

My goal in modifying osis2mod is that it will create 1.5.9 compatible 
modules.

Later, I intend to make modifications that will require 1.5.12. 
(Specifically, an extension of preverse content that we've discussed 
here that will have a preverse div and not just a preverse title.) At 
that time, it would also be appropriate to handle VerseTreeKey as an option.
>   
>> For 3) this is fairly simple, one should not link verses that are not in
>> the KJV versification.
>>     
>
> That seems like a very stringent restriction.  If linking is supported
> for the KJV system, why should it not be allowed for other systems?
> It seems like linking should be fixed in a way to allow everyone to do
> it.
It's not a stringent restriction for the current osis2mod which only 
works for KJV versifications. Later, when osis2mod is upgraded then that 
restriction will need to be removed.

In Him,
    DM