sphack is back (23dec10)

git-svn-id: svn://tug.org/texlive/trunk@20842 c570f23f-e606-0410-a88d-b1316a301751

3 files changed, 229 insertions, 0 deletions

diff --git a/Master/texmf-dist/doc/latex/sphack/sphack-doc.pdf b/Master/texmf-dist/doc/latex/sphack/sphack-doc.pdf
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diff --git a/Master/texmf-dist/doc/latex/sphack/sphack-doc.tex b/Master/texmf-dist/doc/latex/sphack/sphack-doc.tex
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+\documentclass[pagesize=auto]{scrartcl}
+
+\usepackage{fixltx2e}
+\usepackage{etex}
+\usepackage{lmodern}
+\usepackage[T1]{fontenc}
+\usepackage{textcomp}
+\usepackage{microtype}
+\usepackage{hyperref}
+
+\newcommand*{\mail}[1]{\href{mailto:#1}{\texttt{#1}}}
+\newcommand*{\pkg}[1]{\textsf{#1}}
+\newcommand*{\cs}[1]{\texttt{\textbackslash#1}}
+\makeatletter
+\newcommand*{\cmd}[1]{\cs{\expandafter\@gobble\string#1}}
+\makeatother
+
+\addtokomafont{title}{\rmfamily}
+
+\title{The \pkg{sphack} package\thanks{This manual corresponds to \pkg{sphack.sty}~v1.0, dated~22 May 1998.}}
+\author{Oliver Pretzel\thanks{\mail{o.pretzel@ic.ac.uk}}}
+\date{22 May 1998}
+
+
+\begin{document}
+
+\maketitle
+
+\noindent
+Standard \LaTeX\ uses the macros \cmd{\@bsphack}, \cmd{\@esphack}, and \cmd{\@Esphack}, for
+inserts into the text that should be invisible. So, for instance a space
+before and after a \cmd{\label} command should not result in two spaces in the
+output.
+
+\LaTeX\ deals with this as follows
+%
+\begin{itemize}
+\item in maths mode do nothing,
+\item in horizontal mode restore the space factor,
+\item if the last thing on the list was a space
+  add \cmd{\ignorespaces} (and (\cmd{\global})\cmd{\ignore\-true} at the end of an environment),
+\item in vertical mode do nothing.
+\end{itemize}
+
+Doing nothing in maths mode is (nearly) harmless because maths mode does its
+own spacing (and anyway hidden commands will usually appear only at the start
+or end of maths).
+
+Doing nothing in vertical mode is not harmless. Many invisible commands such
+as \cmd{\index} may insert delayed write commands into \TeX's output (so that page
+numbers are correctly calculated). These commands can cause vertical space to
+accumulate, and may cause a page break; \cmd{\index} is a particular problem in
+\LaTeX2.09 since it inserts a delayed write if an index is actually being built
+(\cmd{\makeindex} in preamble) but does nothing otherwise. That can change the page
+breaks in a document.
+
+It is not possible to solve this problem completely in \LaTeX\ because \TeX\ does
+not remove things from the main vertical list once they have been
+contributed. So \LaTeXe\ makes \cmd{\index} insert something into the vertical
+list whether the index is being written or not. That has the virtue of
+consistancy, but is far from ideal. For instance, an \cmd{\index} immediately after
+an \cmd{\item} can cause the page to break between the item label and content.
+
+\pagebreak[2]
+
+The code in the \pkg{sphack} package remedies this fault and other common anomalies so that commands
+are nearly always invisible in vertical mode as well. It works as follows:
+%
+\begin{itemize}
+\item Rename \LaTeX's dimension \cmd{\@savsk} to \cmd{\@savdim} set a new skip \cmd{\@savsk}
+  (because we need a true skip and a dimension in vertical mode)
+
+\item \cmd{\@bsphack} (at start of invisible command)
+  \begin{itemize}
+  \item in hmode (non-math)
+    \begin{enumerate}
+    \item store spacefactor in \cmd{\@savsf}
+    \item store lastskip in \cmd{\@savsk} (used to test whether space already present)
+    \end{enumerate}
+
+  \item in vmode
+    \begin{enumerate}
+    \item store lastpenalty in \cmd{\@savsf}
+    \item store lastskip in \cmd{\@savsk} (used for movement)
+    \item store previous depth  in \cmd{\@savdim}
+    \item skip back \cmd{\lastskip}
+    \end{enumerate}
+  \end{itemize}
+
+\item \cmd{\@esphack} (at end of invisible command)
+  \begin{itemize}
+  \item in hmode (non-math)
+    \begin{enumerate}
+    \item set spacefactor = \cmd{\@savsf}
+    \item if \cmd{\@savsk} > \cmd{\z@} \cmd{\ignorespaces}
+    \end{enumerate}
+
+  \item in vmode
+    \begin{enumerate}
+    \item if in a label, or just after section heading, or if \cmd{\@nobreak}\\
+      insert infinite penalty, (to prevent a page break)\\
+      else insert penalty \cmd{\@savsf}\\
+      endif
+    \item set previous depth = \cmd{\@savdim}
+    \item skip \cmd{\@savsk}
+    \end{enumerate}
+  \end{itemize}
+\end{itemize}
+%
+Just as in standard \LaTeX, \cmd{\@Esphack} is \cmd{\@esphack} + (\cmd{\global})\cmd{\@ignoretrue}.
+
+It is not necessary to change any of the label or index macros to fit with
+this code.
+
+\end{document}
diff --git a/Master/texmf-dist/tex/latex/sphack/sphack.sty b/Master/texmf-dist/tex/latex/sphack/sphack.sty
new file mode 100644
index 00000000000..3761a432cf5
--- /dev/null
+++ b/Master/texmf-dist/tex/latex/sphack/sphack.sty
@@ -0,0 +1,114 @@
+% SPHACK.STY
+% Oliver Pretzel  (o.pretzel@ic.ac.uk)
+% Created 22 May 1998, Version 1.0 22May 1998
+% Modified space hacks for LateX (209 and 2e)
+%   (to prevent \label, \index and similar commands
+%    affecting spacing in vertical mode).
+%
+%
+% DOCUMENTATION at end of file
+%
+% ALL RIGHTS RESERVED
+%
+% This file may be distributed freely.
+% It may be modified for local use (an email copy of the 
+% modified file would be appreciated).
+% Modified versions may only be distributed if
+% 1. The name is changed
+% 2. A statement acknowledging the modification heads the file.
+%
+% DO NOT USE \neq in this file
+\chardef\neq\the\catcode`\@
+\makeatletter\@makeother\"
+%
+
+\typeout{`sphack.sty <1.0>}
+%*************************
+
+\ifx\@savdim\undefined\let\@savdim\@savsk\newskip\@savsk\fi
+\def\@bsphack{\relax\ifmmode\else\@savsk\lastskip\@savsf\ifhmode\spacefactor
+    \else\lastpenalty\@savdim\prevdepth\removelastskip\fi\fi}
+\def\@esphack{\relax\ifmmode\else\ifvmode\penalty\if@nobreak\@M\else
+    \if@inlabel\@M\else\if@noskipsec\@M\else\@savsf\fi\fi\fi
+    \prevdepth\@savdim\vskip\@savsk\else
+    \spacefactor\@savsf\ifdim\@savsk>\z@\ignorespaces\fi\fi\fi}
+\ifx\LateXe\undefined
+\def\@Esphack{\@esphack\ifhmode\ifdim\@savsk>\z@
+    \global\@ignoretrue\ignorespaces\fi\fi}
+\else
+\def\@Esphack{\@esphack\ifhmode\ifdim\@savsk>\z@
+    \@ignoretrue\ignorespaces\fi\fi}
+\fi
+
+% This line must be last line of code
+\catcode`\@\neq\let\neq\ne\endinput
+
+*******************
+  DOCUMENTATION
+*******************
+Standard LaTeX uses the macros \@bsphack, \@esphack, and \@Esphack, for
+inserts into the text that should be invisible. So, for instance a space
+before and after a \label command should not result in two spaces in the
+output.
+
+LaTeX deals with this as follows
+ in maths mode do nothing,
+ in horizontal mode restore the space factor,
+ if the last thing on the list was a space
+   add \ignorespaces (and (\global)\ignoretrue at the end of an environment),
+ in vertical mode do nothing.
+
+Doing nothing in maths mode is (nearly) harmless because maths mode does its
+own spacing (and anyway hidden commands will usually appear only at the start
+or end of maths).
+
+Doing nothing in vertical mode is not harmless. Many invisible commands such
+as \index may insert delayed write commands into TeX's output (so that page
+numbers are correctly calculated). These commands can cause vertical space to
+accumulate, and may cause a page break; \index is a particular problem in
+LaTeX209 since it inserts a delayed write if an index is actually being built
+(\makeindex in preamble) but does nothing otherwise. That can change the page
+breaks in a document.
+
+It is not possible to solve this problem completely in LaTeX because TeX does
+not remove things from the main vertical list once they have been
+contributed. So LaTeX2e makes \index insert something into the vertical
+list whether the index is being written or not. That has the virtue of
+consistancy, but is far from ideal. For instance, an \index immediately after
+an \item can cause the page to break between the item label and content.
+
+The code above remedies this fault and other common anomalies so that commands
+are nearly always invisible in vertical mode as well. It works as follows:
+
+Rename LaTeX's dimension \@savsk to \@savdim set a new skip \@savsk
+  (because we need a true skip and a dimension in vertical mode)
+
+\@bsphack (at start of invisible command)
+in hmode (non-math)
+   store spacefactor in \@savsf
+   store lastskip in \@savsk (used to test whether space already present)
+in vmode
+   store lastpenalty in \@savsf
+   store lastskip in \@savsk (used for movement)
+   store previous depth  in \@savdim
+   skip back \lastskip
+
+\@esphack (at end of invisible command)
+in hmode (non-math)
+   set spacefactor = \@savsf
+   if \@savsk > \z@ \ignorespaces
+in vmode
+   if in a label, or just after section heading, or if \@nobreak
+      insert infinite penalty, (to prevent a page break)
+   else insert penalty \@savsf
+   endif
+   set previous depth = \@savdim
+   skip \@savsk
+
+Just as in standard LateX, \@Esphack is \@esphack + (\global)\@ignoretrue.
+
+It is not necessary to change any of the label or index macros to fit with
+this code.
+
+End of sphack.sty
+*******************