Re: texinfo to docbook - enhancement request

[Patrice Dumas]

On Thu, Feb 06, 2014 at 07:11:08PM +0000, Karl Berry wrote:
> Hi Arnold,
> 
>         @cindex main topic, secondary point, tertiary point
>         ...
>       <indexterm><primary>main topic</primary><secondary>secondary 
> point</secondary><tertiary>tertiary 
> point</tertiary></secondary></primary></indexterm>
> 
> Anyway, as a workaround for your immediate needs, maybe Patrice can
> point you to a hook into the Docbook output where you can tinker with
> the index output easily enough.  Patrice?

That's not easy for 2 reasons.  The first one is that there are no hooks
to customize DocBook output in general.  This means in practice that you
have to change the code directly (_index_entry function in
Texinfo/ConvertDocBook).  The second one is that since it is not a
Texinfo language feature, the tree that represents the output treats the
commas as text.  So, maybe the best would be to manipulate the tree to
split the $index_entry->{'content'} at commas, and then convert each 
split contents.  There are two functions in Texinfo/Common.pm that may
be used to modify the tree, copy_tree(), to copy the tree to avoid
modifying the original tree, and modify_tree() that can be used to 
modify 'args' and 'contents' in tree.  For example, it is used to 
modify a tree representation of 

  A: b
to
  address@hidden:} b

through the function protect_colon_in_tree.

This would be maybe more robust, as it would handle better nested
@commands for instance, but this is not that easy to code.

Of course you can also use a simple regexp to add elements at commas
in _index_entry.


> (BTW, if it were me, I would not use commas, because commas are often
> used in index entries without any desire for subterms.  Even when the
> index does support subterms.  Some magic character like | seems like it
> would be better.  But of course for real support one would want
> @commands anyway.)

I think that this issue really needs to be solved at the Texinfo
language level.

-- 
Pat