Re: Elided page numbers in registers

[Duncan Hothersall <dh@capdm.com>]

On 31 Aug I wrote:

> I have page ranges in my index, such as 1/1-1/3, or 2/24-2/26.
> 
> I would like these ranges to be elided - in other words, the first one
> would read 1/1-3 (remove repeated chapter number), and the second would
> read 2/24-6 (remove repeated chapter number and also the repeated 2 in
> page number).
> 
> Question: is there an already existing system to do this? I guess no :-)
> 
> Followup: I would be willing to help to code this if it doesn't exist (I
> have some experience with such systems) if someone can point me at the
> right bit of code to look at (things seem to be changing around
> texutils, newtexexec etc. so I don't want to start at the wrong place).

Sorry to be a pain, but can anyone help with this? I'm converting a
legacy system, in which everything (cross referencing, tables of
contents, indices) was hand-coded in plain tex and Perl, across to
ConTeXt. The advantage of having hand-coded the indexing stuff was that
I could easily add features like eliding, or funny sort orders. I now
need to reproduce the same output. I suspect I could apply the same
techniques to the ConTeXt code, but I don't want to embark on a fool's
errand if (a) it's already done somewhere, or (b) the code I hack is
about to be replaced.

Thanks,

Duncan