[NTG-context] registers: how can I place a command around the whole of the page numbers of an index term?

MF massifr at fastwebnet.it
Thu May 10 16:43:00 CEST 2018

\wordright is ok until the numbers don't exceed the text width.

It manages these two cases right:

Index term, and some
text  21, 34, 45, 72

Index term, and some
text
21, 34, 45, 72, 89

When the numbers exceed the text width, it fails:

Index term, and some
text
21, 34, 45, 72, 89, 101, 103, 109

It fails because it uses a hbox, that can't do nothing but running
beyond the right margin.

This would be a solution:

Index term, and some
text
21, 34, 45, 72, 89,
101, 103, 109

where the rule is: when the numbers exceed the text width, close the
paragraph, then start a new, right aligned one.

So i wrote this:

---------------------------------------------------
\def\wordorparagraphright#1{\let\scratchWidth\relax
\setbox\scratchbox=\hbox{#1}\newdimen\scratchWidth
\scratchWidth=\wd\scratchbox
\ifdim\scratchWidth < 0.9\textwidth
\wordright{#1}%
\else
\par
\startalignment[flushright]#1\stopalignment
\fi}

\starttext
\input sapolsky \wordorparagraphright{\it other text} \par
\blank
\input sapolsky \wordorparagraphright{\it other text, this time longer}
\par
\blank
\input sapolsky \wordorparagraphright{\it other text, this time
much much much much much much much much much much much much
much much much much much much much much much much longer} \par
\stoptext
---------------------------------------------------

But it doesn't work with

---------------------------------------------------
\unprotect

\unexpanded\def\startregisterpages
{\begingroup
\dostarttagged\t!registerpages\empty
\useregisterstyleandcolor\c!pagestyle\c!pagecolor
\registerparameter\c!pageleft}

\unexpanded\def\stopregisterpages
{\registerparameter\c!pageright
\dostoptagged
\endgroup}

\protect

\def\wordorparagraphright#1{\let\scratchWidth\relax

\setbox\scratchbox=\hbox{#1}\newdimen\scratchWidth

\scratchWidth=\wd\scratchbox
\ifdim\scratchWidth < 0.9\textwidth
\w
ordright{#1}%
\else
\par
\startalignment[flushright]#1\stopalign
ment
\fi}

\setupregister
[index]
[n=1,
alternative=A,
distance=0pt,
pageleft=\wordorparagraphright\bgroup,
pageright=\egroup]

\starttext
\CONTEXT\index{\ConTeXt}
\page
\LATEX\index{\LaTeX}
\page
\CONTEXT\index{\ConTeXt}
\page
\placeindex
\stoptext
---------------------------------------------------

I suppose it's related to the problem that \groupedcommand solves.
Is there a solution?

An even better solution would be:

Index term, and some
text 21, 34, 45, 72,
89, 101, 103, 109

where the rule is: put the text until it fills the current line, than
proceed flushing the remainder of the paragraph lines to the right.

Here i tried changing \leftskip in the middle of a paragraph, but it
works globally.

I think this is even harder to implement, at least in the middle of the
register macros.