[texhax] dotfill leaders on first line of paragraph only ?

[Philip TAYLOR]

Philip TAYLOR wrote:

> and here it is. Please treat it as "proof of concept" only --
> it records (but does not make use of) \lastskip and \lastpenalty,
> and obviously these should be re-inserted into the re-built
> \vtop if it is to be a perfect replica of the one with which
> we started.

The following is, I hope, a final iteration, although if anyone
spots errors in it, do please let me know.  As far as I can
tell, this rebuilds the \vtops correctly, including re-incorporating
the interline glue and penalties.

** Phil.
--------
% !TeX Program=XeTeX

\font \Text = "Palatino Linotype" at 11.25 pt
\font \Vietnamese = "Palatino Linotype: color=0000FF" at 11.25 pt
\font \English = "Palatino Linotype: color=003F00" at 11.25 pt
\font \Seqno = "Palatino Linotype: color=FF0000" at 11.25 pt
\font \Price = "Palatino Linotype: color=0000FF" at 11.25 pt

\newif \ifmore
\newskip \Lastskip
\newskip \Prevskip
\newcount \Lastpenalty
\newcount \Prevpenalty
\tabskip = 0 pt plus 1 fil
\hsize = 24pc
\let \nobreak = ~
\catcode `\~ = \catcode `\@
\parindent = 0 pt
\parskip = 3 ex
\showboxbreadth = 400
\showboxdepth = 3

\def \Note #1{{\Text #1} \vskip 1 ex }

\def \Shewsample #1
	{
		%%% \showbox #1
		\halign {&##\hfil \cr {\Seqno 1. }&\copy #1&{ \Price £9-99}\cr}
	}

\def \Sample #1%
	{
		\setbox 0 = \vtop
			\bgroup
				\parindent = 0 pt
				\raggedright
				\emergencystretch = 1 pt
				\multiply \tolerance by 8
				#1
			\egroup
	}

\def \Dotfilllineone
	{
		\vtop
			\bgroup
				\global \setbox 4 = \vtop {}
				\setbox 6 = \vtop {\box 4 }
				\parindent = 0 pt
				\unvbox 0
				\loop
					\setbox 0 = \lastbox
				\ifvoid 0
					\morefalse
					\global \setbox 4 = \vtop
								{
									\setbox 0 = \hbox to \hsize {\unhbox 2 \unskip \ \dotfill}
									\box 0
									\ifvoid 4
									\else
										\penalty \Prevpenalty
										\vskip \Prevskip
										\unvbox 4
									\fi
								}
				\else
					\moretrue
					\Prevskip = \Lastskip \Lastskip = \lastskip \unskip
					\Prevpenalty = \Lastpenalty	\Lastpenalty = \lastpenalty \unpenalty
					\ifvoid 2
					\else
						\global \setbox 4 = \vtop
									{
										\box 2
										\ifvoid 4
										\else
											\penalty \Prevpenalty
											\vskip \Prevskip
											\unvbox 4
										\fi
									}
					\fi
					\setbox 2 = \box 0
				\fi
				\ifmore
				\repeat
			\egroup
	}

\Note {First test : one-line item}

\Sample {{\Vietnamese Heo nồi đất} \English ~ Minced pork hot pot}
\Shewsample 0
\Dotfilllineone
\Shewsample 4

\Note {Second test : two-line item}

\Sample {{\Vietnamese Heo nồi đất} \English ~ Minced pork hot pot with tofu and aubergine}
\Shewsample 0
\Dotfilllineone
\Shewsample 4

\Note {Third test : three line item}

\Sample {{\Vietnamese Heo nồi đất} \English ~ Minced pork hot pot with tofu and aubergine, topped with peanuts, and with a\nobreak Vietnamese salad on the side}
\Shewsample 0
\Dotfilllineone
\Shewsample 4

\end