registers: setting pageleft parameter by index term

[mf <massifr@fastwebnet.it>]

Hello list, please consider this MWE:

\definenumber[p]
\setnumber[p][1]
\def\PageLeft{ p.~}
\def\TextCommand#1{\getnumber[p] 
#1\doif{\rawcountervalue[p]}{2}{\def\PageLeft{ P.~}}\incrementnumber[p]}
\setupindex[n=1,pageleft=\PageLeft,pageright=,textcommand=\TextCommand]
\starttext
Foo\index{foo}.
\page
Bar\index{bar}.
\page
Baz\index{baz}.
\page
\placeindex
\stoptext

The pageleft parameter of \setupindex (\setupregister) is normally set 
to " p.~", but it gets redefined to " P.~" for the second term in the 
index ("baz").

Here i'm using a counter and i check when it is 2, but i'd like to check 
if the term is "baz" (and i don't know how to do that test).

If you use deeptextcommand instead of textcommand, the pageleft 
parameter can't be redefined.

The following variation compiles, but it does not work, because pageleft 
is always " p.~":

\definenumber[p]
\setnumber[p][1]
\def\PageLeft{ p.~}
\def\TextCommand#1{\getnumber[p] 
#1\doif{\rawcountervalue[p]}{2}{\def\PageLeft{ P.~}}\incrementnumber[p]}
\setupindex[n=1,pageleft=\PageLeft,pageright=,deeptextcommand=\TextCommand]
\starttext
Foo\index{foo}.
\page
Bar\index{bar}.
\page
Baz\index{baz}.
\page
\placeindex
\stoptext

In my setup i must use deeptextcommand, and i want to set the pageleft 
and pageright parameters to a different value for some particular terms 
of the index.

Since the argument passed to deeptextcommand is not the text of the term 
(it's actually an id used to retrieve a much longer text), i can 
discriminate the terms by their id, but i can't setup pageleft and 
pageright accordingly from the command specified by deeptextcommand.

On the other hand, textcommand would let me set pageleft and pageright, 
but its argument is not pure text, and i don't know how to get the id 
from it.

How can i solve this problem?

Thanks,

Massimiliano

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