%%%%%%%%%%%%%%%%%% JAMBOX: RIGHT-COLUMN ANNOTATIONS %%%%%%%%%%%%%%%%
%
% Alexis Dimitriadis
%
% This is version 0.3 (informal release, Nov. 2003).
%
% Line up material a fixed distance from the right margin.  For annotating
% example sentences, usually with a short note in parentheses.
% May overflow to the left or right, or line up on the next line as necessary.
%
% \jambox[width]{text}	Align 'text' starting 'width' distance from the 
%			right margin (default \the\jamwidth).
% \jam(something)	Align a note delimited by parentheses (which are
%			retained).  No optional argument.
% \jambox*{text}        Set \jamwidth to the width of 'text', then align it.
%			(\jamwidth stays set for the rest of the environment).
%
% Notes:
%
% Distance from the right margin can be set to an explicit amount, or to the
% width of some piece of text, as follows:
%
% \jamwidth=2in\relax      Or
% \settowidth\jamwidth {(``annotation'')}
%
% \jamwidth is locally scoped, so it can be set globally or inside an example
% environment.
%
% BUG: Not compatible with ragged-right mode.
%
% Incompatibilities: Not useful with the vanilla cgloss4e.sty, which ends 
% glossed lines prematurely.
% I do have a suitably modified file, cgloss.sty. With it you can do the
% following:
% \gll To kimeno. \\
%      the text \\ \jambox{(Greek)}
% \trans `The text.'


\newdimen\jamwidth \jamwidth=2in
\def\jambox{\@ifnextchar[{\@jambox}
	       {\@ifnextchar*{\@jamsetbox}{\@jambox[\the\jamwidth]}}}

% Quickie invocation: The argument is delimited by the parentheses (no width
% argument allowed). I redefine it in my documents to add formatting.
% Syntax: \jam(Some note)
%  
\def\jam(#1){\jambox{(#1)}} 

% Set width AND display the argument.
% The star is read and ignored; the argument #1 is boxed, used to set
% \jamwidth, then passed to \@jambox (which also puts it in \@tempboxa!)
%
\def\@jamsetbox*#1{\setbox\@tempboxa\hbox{#1}\jamwidth=\wd\@tempboxa
  \@jambox[\the\jamwidth]{\box\@tempboxa}}

%% Version 1: old & stupid
%% \def\@jambox[#1]#2{\hfill\hbox to #1 {#2\hfil}}  

% Version 2:
% Always takes up \jamwidth space, even if it means breaking the line. But it
% works on ragged-right mode, too.
% \def\@jambox[#1]#2{\setbox\@tempboxa\hbox {#2\hfil}%
%	\ifdim \wd\@tempboxa<#1\relax \wd\@tempboxa=#1\relax\fi
%	\hskip 0.5em plus 1fill 
%	\penalty 100\vadjust{}\nobreak\hfill\box\@tempboxa\par}
% The penalty enables a break.  \vadjust inserts an empty element
% at the beginning of the next line, protecting \hfill from being discarded.

% Version 3:
% This seems to cover everything!  But unfortunately, it won't work in
% ragged-right mode-- the line is broken BEFORE the last word, to make enough 
% space...
\def\@jambox[#1]#2{{\setbox\@tempboxa\hbox {#2}%
  \ifdim \wd\@tempboxa<#1\relax % if label fits in the alloted space:
    \@tempdima=#1\relax \advance\@tempdima by-\wd\@tempboxa % remaining \hspace
    \unskip\nobreak\hfill\penalty250 % break line here if necessary
    \hskip 1.2em minus 1.2em 	  % used when the line extends past the margin
    \hbox{}\nobreak\hfill\box\@tempboxa\nobreak
    \hskip\@tempdima minus \@tempdima\hbox{}%
  \else  % the label is too wide: just right-align it
    \hfill\penalty50\hbox{}\nobreak\hfill\box\@tempboxa
  \fi
  % suppress closing glue:
  \parfillskip=0pt \finalhyphendemerits=0 \par}}
% The penalty enables a break, taken only if the line cannot fit.
% The \hbox{} ensures the next line does not begin with \hfill, which would
% be discarded if initial.
% (\vadjust inserts an empty element at the beginning of the next line, so
% that COULD be used instead of \hbox{}).
% Algorithm adapted from The TeXBook.
%
% The closing \par could be a problem if there is a \parskip...