%    ^^A WEBFILES.DTX  $Revision: 2.1 $
%    ^^A LaTeX package webfiles, documented with DOC,
%    ^^A for use with DOCSTRIP.
%
%
%    \title{The \texttt{webfiles} Package \\ Version~\xwebVersion}
%    \author{Mark Potse%
%       \thanks{Medical Physics Department, University
%          of Amsterdam. \newline
%          Email: {\tt M.Potse@amc.uva.nl}
%          }\\
%       }
%    \date{\xwebDate}
%    \maketitle
%
%    ^^A an environment to extend the doc macros:
%    ^^A (cannot be nested!)
%    \newtoks\Macros
%    \catcode`\@=11
%       \def\macros{\begingroup  ^^A defines \begin{macros}{#1}
%          \catcode`\\=12
%          \catcode`\  =9      ^^A ignore spaces, tabs, and newlines
%          \catcode`\^^I=9
%          \catcode`\^^M=9
%          \MakePrivateLetters
%    	   \scanmacros}
%       \def\scanmacros#1{%
%    	   \global\Macros={#1}
%          \endgroup
%    	   \@for\tmpa:=#1\do{
%               \expandafter\macro \expandafter{\tmpa}}}
%    	\def\endmacros{
%           \@for\tmpa:=\the\Macros\do{\endmacro}}
%    \catcode`\@=12
%
%
%    ^^A don't print macros in the margin; there are too many of them
%    \def\PrintMacroName#1{}
%    \MacroTopsep=-10pt
%
%    
%    \section{Introduction}
%
%    The \texttt{webfiles} package makes it possible to plug the
%    documentation of \cweb\footnote{version~3, this package does not
%    work with older versions} and Spidery \web\ programs into a
%    \LaTeX\ document.  One can include any number of webs by
%    including the \weave\ processor's output with the command
%    \begin{quote}
%           |\webfile[|\meta{options}|]{|\meta{filename}|}|
%    \end{quote}
%    where \meta{filename} is the name of the \texttt{.tex} file (with
%    or without the extension) that
%    is output by the \weave\ processor and \meta{options} is a
%    comma-separated list of options, as explained later.
%    Of course, the \texttt{webfiles} package must be loaded:
%       \begin{quote}
%          |\usepackage[|\meta{options}|]{webfiles}|
%       \end{quote}
%       in the preamble of the document. The package recognizes the same
%       options as the |\webfiles| command.
%   
%    This manual does not describe the usage of \web{} systems
%       themselves; they have their own
%       manuals\cite{cweb:manual,spiderywebman,mweb:manual}.
%    In what follows, it is assumed that you read at least one of them, but
%       note that some of the information here overrides what was said
%       there.
%    
%    This package is based on the {\tt cweb} style
%       by Joachim Schrod (even this manual is based on his).
%    Apart from the fact that, with this package, {\tt web}'s are `plugged in'
%       while in Schrod's style they are the main and only body, there is a
%       number of differences:
%       \begin{enumerate}
%       \item This package can also work with Spidery webs.
%       \item The layout (determined by the document class and maybe
%             other packages) is not changed.
%       \item Existing counters are not affected.
%       \item The section numbers in \weave's output are used.
%       \item The contents of all webs are listed in a ``List of
%             Programs'', if the user wishes so.
%       \item The user may choose if pagebreaks may occur inside
%             sections. If not, the result is a `ragged bottom'.
%       \item A section is only printed if it is `on'. (Refer to the
%             documentation of 
%             a \web\ to see what `on' means in this context.)
%       \item The \texttt{multicol} package is used, if present, to
%             typeset the identifier index in two columns. Therefore a
%             pagebreak between the identifier index and the list of
%             refinements is no longer necessary. If \texttt{multicol}
%             cannot be found, \LaTeX's \verb"\twocolumn" is used.
%       \item The index and list of refinements can be suppressed in
%             the \LaTeX{} document.
%       \item Format (|@f|) statements can be suppressed in the \LaTeX{}
%             document.
%       \item Support for hyperlinks is included, as well as direct
%             support for PDF\TeX.
%       \end{enumerate}
%
%
%    
%
%
%    \subsection{The overall structure}
%    
%    The philosophy behind this package is that you, like it's
%    author, may wish to import more than one \web\ program, maybe in
%    more than one programming language, in a single \LaTeX\ document. 
%    With this package, you can regard to the {\tt .web} file as just
%    a part of your document, like the parts that you |\include|
%    when writing a large document in more than one file, and in the
%    documentation parts of the \web{} program you can use all features of
%    \LaTeX\ the way you would in that case.
%
%     \cweb{} Version~3.0 introduced the notion of a starred section's
%    ``depth.'' As 
%    in the layout produced by {\tt cwebmac.tex} the depth value does only
%    influence  the web's table of contents (and ``List of
%    Programs''), not the rendering of the 
%    title within the text. (\texttt{cwebmac.tex} is the original,
%    plain-based macro package used to typeset \cweb{} sources; I
%    refer henceforth to it as the ``plain version.'')
%
%    The \emph{document} structure is tagged in the mother document, with
%    \verb"\section" and such. Although it is not forbidden to use
%    sectioning commands in the documentation part of the \web{}
%    program, it doesn't seem useful to do so. The only place where a
%    sectioning command could be useful is in the limbo section.
%
%    The `mother document' must load the ``{\tt webfiles}'' package:
%    \begin{quote}
%    \verb"\usepackage{webfiles}"
%    \end{quote}
%    Then you can include a \web{} program with the following command:
%    \begin{quote}
%        \verb"\webfile{"\meta{filename}\verb"}"
%    \end{quote}
%    where \meta{filename} is the {\tt .tex} file that is
%    output by  a \weave\ processor.
%
%    The resulting structure of the mother document is exemplified in
%    figure~\ref{fig:structure}. Text may be inserted anywhere
%    inbetween the tags shown there.
%    
%    \begin{figure}[t]
%    
%      \setbox0=\vbox{\parindent=0pt \hsize=.9\textwidth
%      \begin{minipage}{\hsize}
%      \begin{verbatim}
%        \documentclass{report}
%        \usepackage{webfiles}
%        
%        \begin{document}
%    
%        \title{Three solutions for the Travelling Salesman problem}
%        \author{Joe L. User}
%    
%        \maketitle
%    
%        \tableofcontents    % optional
%        \listoffigures      % etc., optional
%        \listofprograms     % optional
%    
%        \chapter{A PSPACE solution for the Travelling Salesman}
%        \webfile{pspace}
%        
%        \chapter{The Travelling Salesman problem, solved by Simulated
%          Annealing} 
%        \webfile{anneal}
%        
%        \chapter{A Neural Network solution for the Travelling Salesman}
%        \webfile{neu_net}
%        
%        \appendix
%        \chapter{The Travelling Salesman Problem, solved by telepresence}
%        \input{internet-user}
%         
%        \end{document}
%    
%      \end{verbatim}
%      \end{minipage}
%    }
%    
%    \begin{center}
%    \fboxsep=1em
%    \fbox{\box0}
%    \end{center}
%    
%    \caption{Exemplified document structure}
%    \label{fig:structure}
%    \end{figure}
%
% 
% \subsection{Notes on running weave processors}
% 
% \begin{itemize}
% \item Recent versions of Levy \&\ Knuth's \texttt{cweave} should be
%   run with the \texttt{+e} flag to work correctly with the
%   \texttt{webfiles} package (if this flag is omitted, program code
%   fragments between vertical bars in the documentation part will not
%   be printed correctly).
% \item If \texttt{cweave} or a Spidery weave is run with the |-x|
%   option, a (harmless) error message occurs about a file that ``ended
%   while scanning use of |\end|''.
% \end{itemize}
% 
%    
%    \section{Customization}
%
%    Both the |\webfile| command and the |\usepackage{webfiles}|
%    command accept an optional argument that may contain a
%    comma-separated list of options. Options specified to
%    |\usepackage| act as global defaults that can be overridden in
%    the optional argument to |\webfile|. Therefore each option has an
%    opposite. The recognized options are summarized in
%    table~\ref{opttab}, and discussed in the following sections.
%    \begin{table}
%      \def\*{*}
%      \begin{center}
%      \begin{tabular}{llp{8cm}}
%        \textit{option} & \textit{opposite} & \textit{effect} \\[4pt]
%        |index|\*     & |noindex| & print identifier index \\
%        |noindex|     & |index|   & don't print identifier index \\
%        |reflist|\*   & |noreflist| & print List of Refinements \\
%        |noreflist|   & |reflist|   & don't print List of Refinements \\
%        |contents|\*  & |nocon| & print table of contents\\
%        |nocon|       & |contents| &  don't print table of contents\\
%        |allsections|\* & |onlychanges| & print all sections\\ 
%        |onlychanges| & |allsections| & print only changed sections\\ 
%        |showformats|\* & |hideformats| & show |@f| declarations \\
%        |hideformats|   & |showformats| & don't show |@f| declarations \\
%        |raggedbottom|\* & |flushbottom| & try not to break modules
%                                           across pages \\
%        |flushbottom| & |raggedbottom| & try to create a flush
%                                      bottom, break modules if necessary \\
%        |hyperref| & |nohype| & make hyperlinks using |hyperref| package\\
%        |pdftex| & |nohype| & make hyperlinks and PDF outlines with
%                                PDF\TeX\\
%        |nohype|\* & \ldots & no hyperlinks\\
%        |nofiles|    & |writefiles| & dont't write a contents file
%        (equivalent to setting |\setcounter{xwebLopDepth}{-9}|).\\
%        |writefiles|\* &  |nofiles| & do write a contents file.
%        (equivalent to setting |\setcounter{xwebLopDepth}{9}|).\\
%      \end{tabular}
%      \end{center}
%      \caption{Webfiles options. Defaults are tagged with a \*.}
%      \label{opttab}
%    \end{table}
%    Other customizations are possible through the redefinition of
%    macros and the setting of counters; the most important of these
%    will be explained in this section.
%
%    
%    \subsection{The index and the list of refinements}
%    
%    An identifier index and a list of refinements are created  at the
%    end of each  \web{} document, if you didn't call \weave{} with
%    the {\tt -x}  
%    option\footnote{%
%       The `{\tt-x}' option suppresses output of the index and
%    reflist---see the documentation.}.
%    You can specify an introductionary text for the index with
%    the tag \verb"\xwebIndexIntro", the introduction is the argument of this
%    tag.
%    To suppress generation of an identifier index, even when \weave{}
%    was not called with the {\tt -x} option you can use an optional
%    argument to the |\webfile| command; for example:
%    \begin{verbatim}
%       \webfile[noindex]{foo}
%    \end{verbatim}
%    To suppress identifier indexes in all web's, use this option in
%    the |\usepackage| command:
%    \begin{verbatim}
%       \usepackage[noindex]{webfiles}
%    \end{verbatim}
%    You can use the |index| option in the |\webfile| command to
%    override this global default.
%
%    The same applies to the list of refinements, using the options
%    |reflist| and |noreflist|.
%    
%
%    \subsection{The table of contents}
%
%    Each web document gets its own table of contents. It can be suppressed
%    with the |nocon| option; the opposite option is |contents|.
%    You can produce the table of contents of any web document in any
%    position with the |\xwebContents| command. This command takes one
%    argument: the basename of the web document, and does not work
%    with Spidery webs (yet\footnote{I consider releasing a revised
%    version of Spider that is more compatible with CWEB, and has less
%    bugs}).
%
%    The tables of contents are produced like all \LaTeX's tables of contents
%    etc., in the second \LaTeX\ run. They are stored in a file with name
%    \meta{basename}\texttt{.con}, where \meta{basename} is the basename
%    of the web document.
%    
%    
%    \subsection{The List of Programs}
%
%    In addition to 
%    the table of contents there is a
%    ``List of Programs'', analogous to the ``List of Figures''
%    etc.~that standard \LaTeX{} provides. 
%    The list can be produced with a 
%    \begin{verbatim}
%      \listofprograms
%    \end{verbatim}
%    command, which can be placed at any position. 
%    It is customary to put it at the beginning of the mother
%    document, after it's table of contents.  
%    As with the List of Figures, the List of Programs is generated at
%    the second \LaTeX{} run. It can list programs, main sections and
%    normal sections; the default is to list only programs and main
%    sections. You can control what goes into the list by setting the
%    counter {\tt xwebLopDepth\/}: 
%    \begin{itemize}
%    \item Normal sections get into it if {\tt xwebLopDepth\/} is
%          greater than or equal to 10.
%    \item All starred sections that have a depth smaller than  {\tt
%          xwebLopDepth\/} will be mentioned.
%    \item Programs will be mentioned unless {\tt xwebLopDepth\/} is
%          smaller than or equal to $-10$.
%    \end{itemize}
%    By setting {\tt xwebLopDepth\/} inbetween \verb"\webfile"
%    commands you can handle each \web{} file differently, if you
%    wish. 
%    The default value is 9.
%    It is a \LaTeX{} counter, so its value can be changed using the
%    \verb"\setcounter" and 
%    \verb"\addtocounter" commands.
%
%    The PDF outline (if you use PDF\TeX) can be controlled in the
%    same way, using the counter \texttt{xwebOutlineDepth}, except
%    that normal sections never get into the outline.
%    
%    The entries for the List of Programs are put into the file 
%    ``{\meta{jobname}\tt.lop}'', where \meta{jobname}
%    is the jobname that \TeX\ chose for the mother document (usually
%    the name of the {\tt.tex} file, without the extension). 
%    Edit this file only if you're desparate, as with the {\tt.toc} and
%    {\tt.lof} files etc. 
%    
%    
%    
%    \subsection{Newpages}
%    
%    The default behaviour of the |webfiles| package is never to break
%    sections across pages if they fit on a single page.
%    If sections may be broken across pages, the |webfiles| package
%    is able create `flush bottom' pages.
%    To enable this, specify the |flushbottom| option to the
%    |\webfile| or the |\usepackage| command.
%    To re-enable the default behaviour locally, specify the
%    |raggedbottom| option.
%    
%    A main section can start a new page regardless if it will fit on
%    the current one. To change this behaviour,
%    set the counter 
%    {\tt xwebSecNoEject}, which keeps the lowest group level where
%    no new page is started at a main section. The default is~3.
%    It is a \LaTeX{} counter, so its value can be changed using the
%    |\setcounter| and |\addtocounter| commands.
%
%
%    \subsection{Hyperlinks}
%
%    If the |hyperref| option is specified, all module references are
%    turned into hyperlinks using the \texttt{hyperref}
%    package\cite{hyperref}. To use this feature, you have to import the
%    \texttt{hyperref} package yourself, before importing the
%    \texttt{webfiles} package, e.g.:
%    \begin{verbatim}
%      \usepackage[hypertex]{hyperref}
%      \usepackage[hyperref]{webfiles}
%    \end{verbatim}
%    Alternatively, with the |pdftex| option, direct support for PDF\TeX\
%    can be enabled. This provides the same look and feel as the
%    \texttt{pdfcwebmac} macros, including the `PDF Outline', but of
%    course works only with PDF\TeX.
%
%    Both types of hyperlinked references can be switched off with the
%    |nohype| option. 
%    
%
%    \subsection{Output in other languages}
%    
%    \web\ documentation can contain a few---predefined---informal texts.
%    As in the plain version, you can change these texts, for example
%    to obtain output in an other language than English, by redefining
%    some macros. The macro names concerned are listed below, together
%    with their default definitions. 
%    \begin{verbatim}
%    
%    \def\xwebIndexName{Index of \xwebJobname}
%    \def\xwebReflistName{List of Refinements in \xwebJobname}
%    \def\xwebCRAlso{\xwebCrossRef{See also section}}
%    \def\xwebCRsAlso{\xwebCrossRef{See also sections}}
%    \def\xwebCRCite{\xwebCrossRef{This code is cited in section}}
%    \def\xwebCRsCite{\xwebCrossRef{This code is cited in sections}}
%    \def\xwebRLCite{\xwebCrossRef{Cited in section}}
%    \def\xwebRLsCite{\xwebCrossRef{Cited in sections}}
%    \def\xwebCRUse{\xwebCrossRef{This code is used in section}}
%    \def\xwebCRsUse{\xwebCrossRef{This code is used in sections}}
%    \def\xwebRLUse{\xwebCrossRef{Used in section}}
%    \def\xwebRLsUse{\xwebCrossRef{Used in sections}}
%    \def\xwebCRChanged{%
%       \xwebCrossRef{The following sections were changed by the change file:}%
%       \let\*\relax}
%    \def\xwebCREt{ and~}
%    \def\xwebCRsEt{, and~}
%    \def\xwebLopName{List of Programs}
%    \def\xwebTocName{Contents of \xwebJobname}
%    \def\xwebRefMacrosHere{Preprocessor Definitions}
%    \def\xwebSectionName{Section}
%    \def\xwebPageName{Page}
%    
%    \end{verbatim}
%
%
%    \subsection{Documenting changefiles}
%
%    If a web file is included that has some sections changed by a
%    changefile you can have the |\webfile| command print only the
%    changed sections by giving the |onlychanges| option.
%    As with all options, this option can also be given to the
%    |\usepackage| command. Its opposite option is |allsections|.
%    Specifying |onlychanges| is equivalent to saying
%    |\let\maybe=\iffalse| in the plain version.
%
%    
%    
%    \subsection{Miscellaneous}
%
%    You can control the appearance of web section numbers by redefining
%    the appearance of |\thexwebModule|. Its default definition is
%    |\arabic{xwebModule}|.
%
%    With the |noformats| option, you can suppress the printing of
%    |@f| specifiers. (In cweb, you can also use |@s| instead of |@f|,
%    that way you can control which format specifiers get printed and
%    which don't).
%    
%    
%    \section{Problems and Restrictions}
%    
%    Restrictions:
%    \begin{itemize}
%    
%    \item Please be aware that the vertical bar (`\verb"|"') is used
%          by \web{} to delimit small program code pieces in the
%          documentation parts, and is therefore processed by
%          \weave{}. {\it You cannot use it for \LaTeX{} anymore.}
%    
%          In particular, you cannot specify rules for the {\tt
%          tabular\/} or the 
%          {\tt array\/} environment. Since you probably want to do
%          so: You have two choices left:
%     
%          \begin{enumerate}
%          
%          \item Make sure you have the {\tt array\/} package (by Frank
%            Mittelbach 
%            and David Carlisle) installed. Then you may use the package
%            {\tt cwebarray\/}, it defines `{\tt I\/}' (that's an uppercase~i)
%            as a specifier 
%            for rules. I.e., instead of 
%            \begin{verbatim}
%               \begin{tabular}{l|l}
%            \end{verbatim}
%            you have to write
%            \begin{verbatim}
%               \begin{tabular}{lIl} 
%            \end{verbatim}
%          
%          \item \begin{sloppypar}
%            Use `\verb"^^7c"' instead of `\verb"|"'. I.e., instead of
%            \verb"\begin{tabular}{l|l}" you may write
%            \verb"\begin{tabular}{l^^7cl}". 
%            \end{sloppypar}
%          
%          \end{enumerate}
%          %
%         These two choices are compatible, you may use both in one document.
%         Needless to say, I consider the first alternative the better one.
%    
%    \item One cannot use restricted program mode in moving
%          arguments. Most 
%          notably, this is annoying in the titles of starred sections
%          and in 
%          \verb"\caption" tags. 
%    
%    \begingroup
%    \hfuzz=10pt        ^^A 9.89442pt too wide at a4-9
%    \item Neither a refinement name nor an index entry made
%          by~|@^| may consist of a {\it single\/} dot-accented
%          term. I.e., you must not write `|@<\.O@>|', `|@^\.o@>|', or
%          even `|@^\.{foolish}@>|'. Of course you may write
%          `|@^\.o accent@>|' or `|@< Handle accent \.o @>|'.
%    \endgroup
%
%    \item If weave is run with the |-x| option, a (harmless) error
%          message occurs about a file that
%          ``ended while scanning use of |\end|''.
%    
%    
%    \end{itemize}
%    
%    
%    \subsection{Reserved Control Sequences}
%    
%    The following tags are reserved and must neither be used nor
%    redefined:
%    \begin{verbatim}
%     \ATL
%     \B
%     \M
%     \N
%     \PB
%     \Y
%    \end{verbatim}
%    
%    \verb"\9" is already explained in the \cweb{} user manual: It's a special
%    control sequence used for the index entries tagged with~`\verb"@:"'. Its
%    default definition is setup in such a way that you can cheat
%    \weave{} concerning the sort order of this entry: If you enter
%    `\verb"@:sort}{print@>"' you will get an index entry ``print'' next to the
%    place where the index entry ``sort'' would be. But you're allowed to
%    change this default definition.%
%    
%    The names of all other control sequences defined by this
%    package---besides the common \LaTeX{} control sequences---start with
%    \texttt{xweb}. Please don't define new control
%    sequences starting with this prefix. (The control sequences that
%    don't have a `|@|' or `|_|' in them may be
%    redefined to change the appearence of the \web{}
%    document, check the implementation's documentation for their
%    meaning.)
%    
%    
%    
%    
%    \subsection{Problems} \label{sec:problems}
%     Since this is still a test version of the package, there are some
%    known bugs and problems.
%    
%    \bigskip
%    
%    \noindent {\it Known Bugs\/}:
%     %
%    \begin{itemize}
%    
%    \item The presentation of \verb"@l" redefinitions is not proper. But it
%    wasn't in the plain version, either.
%    
%    \end{itemize}
%    
%    \noindent {\it Problems\/}:
%     %
%    \begin{itemize}
%    \item One cannot use an other basic font size than 10\,pt. A few
%      symbol definitions and layout parameters depend on this.
%    \item \C++ comments in \cweb\ (i.e., from \verb"//" to the end of
%      the line) are 
%      typeset as C comments. This is especially bad if they are used for a
%      whole block of comment lines, as it is quite common. Please put such
%      comment blocks in the documentation part.
%    \end{itemize}
%    
%    
%    
%    \section{\TeX nical Data}
%    
%    \web{} programmers who used the plain version before
%    should note that the macros from {\tt cwebmac.tex} and {\tt
%    webkernel.tex} are not available anymore.  
%    E.g., you cannot use \verb"\." to typeset typewriter material; use
%    either |\texttt| or~|\verb|, as it fits the situation. On
%    the other hand, 
%    now you're able, for example, to use |\.| for the dot accent, 
%    |\\| will be the newline again (as usual in \LaTeX),
%    you can define  |\C++| for the \C++\ logo, etc.
%    
%    Another detail for ex-plainies: The ``List of Programs'' that
%    replaces the table of contents is produced by 
%    the \verb"\listofprograms" tag (during the second \LaTeX{} run), not
%    automatically. But this is the standard \LaTeX{} way of handling
%    such things.
%    
%    There are now two kinds of indexes, both optional: Those that are
%    created by \weave{}, which come at the end of each \web{}
%    program, and the index of the mother document, that is, the one
%    that is created with \verb"\index" commands and the {\tt
%    theindex\/} environment (possibly with the help of
%    \MakeIndex\/\cite{makeindex}). 
%    There are no problems in using these together, but it's for you
%    to decide in which of them the entries must go that you specify
%    yourself.  
%    You may, with a few definitions, get the indexes of the \web{}
%    files into the index of the mother document. 
%    
%    The modules are put in a new environment, called
%    \verb"xwebModule". They are not made into \verb"\section"s and
%    such, and they are numbered in a single layer, in exactly the
%    same way as in the plain version, so that the cross-reference
%    information output by \weave\ will always be right. (It refers
%    literally to the section numbers.) 
%    
%    You can change this, e.g., you can let \verb"xwebModule"s be
%    \verb"\section"s, but you'll have to change the way
%    cross-references are printed too. For more information, consult
%    the documentation\cite{webfiles}.
%
%    The \texttt{webfiles} package is documented with the \texttt{doc}
%    package, and uses \texttt{docstrip} to create its \texttt{.sty}
%    files. See the \emph{\LaTeX\ Companion} or the \texttt{README}
%    file that goes together with the \texttt{webfiles} package for
%    instructions on how to use these to change the sources or produce
%    typeset documentation.
%    
%    This package reserves the namespace |xweb|.
%    
%    
%    \subsection{Files}
%    
%    \def\xweave{{\tt{\it x\/}weave}}
%    \def\xweb{{\tt{\it x\/}web}}
%    
%    \begin{description}
%    \item[{\tt webfiles.sty}] is the main package file.
%    It suffices to handle \cweb\ files. 
%    \item[{\tt cwebmac.tex}] is the macro package that is input on
%    the first line 
%       of the {\tt .tex} file that \cweave\ creates. It contains
%    macros that enable  
%       \TeX\ to handle \cweb, but it can see if it's being input by
%    \LaTeX\ (instead 
%       of \TeX\/), and, if so, it won't define anything.
%    \item[{\tt{\it x\/}web.tex}] is the file that is input on the
%       first line of  
%       output of \xweave, where \xweave\ is a Spidery \weave.
%       It inputs {\tt webkernel.tex}, and defines additional macros that are
%       specific for \xweb. The person that made \xweb\ should make
%       sure that these  
%       macros work with \LaTeX\ too.
%    \item[{\tt webkernel.tex}] is input by {\tt{\it x\/}web.tex}; it
%       is the Spidery 
%       analogon of {\tt cwebmac.tex\/}, but
%       it contains no language-dependent macros: These are concentrated in the
%       {\tt{\it x\/}web.tex} files.
%       If {\tt webkernel.tex} sees that it is being input by \LaTeX, it inputs
%       {\tt swebbind.sty}, and doesn't define anything, else it
%       defines the macros  
%       that enable \TeX\ to handle a Spidery \web{}.
%    \item[{\tt swebbind.sty}] contains redefinitions of some macros in {\tt 
%       webfiles.sty} that 
%       make them able to handle Spidery \web{}s.
%    \end{description}
%    %
%    {\tt webfiles.sty} and {\tt swebbind.sty} are supplied with the
%    {\tt webfiles} package. 
%    So is {\tt webkernel.tex}; this file replaces the file of the
%    same name that goes together with \spider. 
%    The {\tt{\it x\/}web.tex} files are supplied with their
%    respective (Spidery) \web{}s. 
%    {\tt cwebmac.tex} is supplied with \cweb.
%    
%    \filbreak\subsection{Bug reports}
%    
%    If you have any comments on the {\tt webfiles\/} package
%    that may be of interest to others, please report them to the
%    author:   
%    \begin{quote}
%      \parbox{\textwidth}{
%       Mark Potse\\
%       Medical Physics department,\\
%       Academic Medical Center\\
%       Meibergdreef 15,\\
%       1105 AZ Amsterdam,
%       The Netherlands.\\
%       email: \texttt{M.Potse@amc.uva.nl}}
%    \end{quote}
%    You may be able to fix bugs or customize the package after
%    consulting the documentation that goes
%    together with this manual. 
%
% 
% \section{Acknowledgements}
% 
% Most of the code in this package was shamelessly stolen from the
% \texttt{cweb} style by Joachim Schrod (even this manual is based on
% his). Thanks to Andreas Scherer and Amelie Stein for useful
% comments. And if God had not given us \TeX\ it would have been
% necessary to invent it.
% 
% 
%    
% \StopEventually{
%     \bibliographystyle{unsrt}
%     \bibliography{webfiles}
%     \addcontentsline{toc}{section}{Bibliography}}
%
%
%
%
% \chap The documentation driver.
%
%    \DoNotIndex{\#,\$,\%,\&,\@,\\,\{,\},\^,\_,\~,\ }
%    \DoNotIndex{\@ne}
%    \DoNotIndex{\advance,\begingroup}
%    \DoNotIndex{\begin,\bf,\bigskip}
%    \DoNotIndex{\catcode,\closein,\closeout}
%    \DoNotIndex{\copy,\csname,\cdot,\char,\chardef}
%    \DoNotIndex{\day,\def,\edef,\else,\empty,\endcsname,}
%    \DoNotIndex{\endgroup,\errmessage}
%    \DoNotIndex{\expandafter,\fi,\futurelet,\gdef,\global,\hbox,\if,\ifeof}
%    \DoNotIndex{\ifx,\immediate,\let,\loop,\m@ne,\message,\month}
%    \DoNotIndex{\newcount}
%    \DoNotIndex{\newif,\newlinechar,\newread,\newtoks,\newwrite}
%    \DoNotIndex{\noexpand,\par,\read,\relax,\repeat}
%    \DoNotIndex{\space,\the,\undefined,\write,\xdef,\year,\z@}
%
%    The \texttt{webfiles} package is documented with \texttt{docstrip}.
%    This code will generate the documentation. Since it is the first piece
%    of code in the file, the documentation can be obtained by simply
%    processing this file with \LaTeXe.
%
%    \begin{macros}{\MakePrivateLetters}
%    \begin{macrocode}
%<*driver>
\documentclass[twoside]{ltxdoc}
\usepackage{xwebdoc,array,cwebarray}
\pagestyle{headings}
\renewcommand\MakePrivateLetters{\makeatletter\catcode`\_=11\relax}
\IndexPrologue{\section*{Index}%
   \markboth{Index}{Index}%
     The italic numbers denote the code lines where the corresponding
     entry is described, underlined numbers point to the definition,
     all others indicate the places where it is used.}
\EnableCrossrefs
\CodelineIndex % \RecordChanges
% \OnlyDescription
%</driver>
%    \end{macrocode}
%    \end{macros}
%    
%    
%    \sect The RCS version number is extracted from the keyword string
%    and joined with the manually-set major version number.
%    The complete version number is also written in
%    ``\texttt{version.tex}'' for use in the Makefile.
%
%    \begin{macros}{\xwebMajor,\xwebVersion,\xwebDate}
%    \begin{macrocode} 
%<*driver|main>

%%
%% $Id: webfiles.dtx,v 2.1 2002/03/05 10:38:14 potse Exp $
%%

\begingroup
   \catcode`\$=9  % ignore $
   \gdef\xwebMajorNr{1.0.}
   \def\setversion#1:#2.#3:{\xdef\xwebVersion{\xwebMajorNr #3}}
   \setversion $Revision: 2.1 $:
   \def\setdate#1: #2/#3/#4#5#6:#7:#8;{\gdef\xwebDate{#2/#3/#4#5}}
   \setdate $Date: 2002/03/05 10:38:14 $;
   \newwrite\vf \immediate\openout\vf=version.tex
   \immediate\write\vf{\xwebVersion}\immediate\closeout\vf
\endgroup
%</driver|main>
%    \end{macrocode}
%    \end{macros}
%    
%    
%    \sect After that, the document can be input by the driver.
%    
%    \begin{macrocode}
%<*driver>
\begin{document}
   \DocInput{webfiles.dtx}
   \PrintIndex
   % \PrintChanges
\end{document}
%</driver>
%    \end{macrocode}
%
%    
%    \chap Implementation.
%    
%    The implementation is still somewhat messy.
%   
%    A good explanation of the vocabulary used here is given by Schrod
%    in the implementation of the {\tt cweb} style:
%
% \begin{quotation}
% 
% Before we start with an overview of the implementation I want to
% explain the \cweb{} vocabulary I use while I guide you through this
% document. The commonly used terms sometimes denote two entities, but
% for the purpose of this style we need exact terms. I've tried to stick
% to a ``canonical'' computer science terminology.
% 
% I distinguish two different structures in a \cweb{} file: The 
% \emph{document structure} and the \emph{program structure}.
% 
% A \cweb{} document consists of a series of \emph{sections}. Within
% this series some sections are especially emphasized, we call them the
% \emph{main sections}. (They are also called \emph{starred sections},
% since their corresponding \cweb{} tag is~|@*|.) These main sections
% have a title, ordinary sections are untitled. A table of contents may
% therefore list only the main sections. Note that there is no
% hierarchy in the sections, they are all on the same level, i.e., they
% are numbered subsequently.
% 
% Each section consists of three parts: (1)~the \emph{documentation
% part}, (2)~the \emph{definition part}, and (3)~the \emph{program part}.
% Each of these parts can be empty. The documentation part is mostly text
% with \LaTeX{} tags. In this text material from \emph{restricted program
% mode} can appear. The definition part consists of a series of either
% \emph{macro} or \emph{format definitions}. The program part is one
% piece of a refinement, identified by a name (see below).
% 
% A \cweb{} program consists of a tree of \emph{refinements}. A
% refinement is a list of program parts with the same name, ordered in
% appearence. The root of the tree is the refinement with the special
% name~|@c|. The program text is defined by the DFS (i.e., infix-order)
% traversal of the tree.
% 
% \end{quotation}
% 
%  
%    \sect
%    Before we start we declare some names for category codes. By
%    declaring the underscore~`(|_|)' as letter we can use it in our
%    macros.  As this is a \LaTeX{} package the at sign is a letter
%    anyhow; so we can use the ``private'' plain and \LaTeX{} control
%    sequences; and with the underscore we can make our own control
%    sequences (\emph{cseqs} for short) more readable. Since we have to
%    restore this category code at the end of this macro file, we save its
%    former value in the control sequence |\xwebCatUsCode|.
%    This method is better than to use a group, not all cseqs must be
%    defined global this way. 
%
%    \begin{macros}{\xwebCatEscape,\xwebCatOpen,\xwebCatClose,
%       \xwebCatIgnore,\xwebCatLetter,\xwebCatOther,\xwebCatActive,
%       \xwebCatUsCode}
%    \begin{macrocode}
%<*main|spider>
\catcode`\@=11
\chardef\xwebCatUsCode=\catcode`\_       % top level macro file!
\catcode`\_=11 % Catcode letter
\chardef\xwebCatEscape=0
\chardef\xwebCatOpen=1
\chardef\xwebCatClose=2
\chardef\xwebCatIgnore=9
\chardef\xwebCatLetter=11
\chardef\xwebCatOther=12
\chardef\xwebCatActive=13
%</main|spider>
%    \end{macrocode}
%    \end{macros}
%  
%  
%    \sect Let's identify this package against the user and in the Log file.
%  
%    \begin{macrocode}
%<*main>
\ProvidesPackage{webfiles}
\begingroup
    \typeout{LaTeX package `webfiles', version \xwebVersion, \xwebDate}
\endgroup
%</main>
%    \end{macrocode}
%
%    \sect The very first (alpha) version of the {\tt cweb} style was a style 
%    option.
%    The version on which the {\tt webfiles} style is based was a full style.
%    {\tt webfiles.sty} itself is an option again, and since the author
%    has \LaTeXe, it has become a \emph{package}.  
%    Therefore we test if a documentclass was chosen (by testing if
%    |\section| is defined).
%  
%    \begin{macrocode}
%<*main>
\ifx \section\undefined 
    \PackageError{webfiles}{`webfiles' is a package, not a class}{%
        webfiles is not a document class, but only a package.
        Please adapt your documentclass tag appropriately. 
        I.e., write \MessageBreak
        \protect\usepackage{webfiles} instead of 
        \protect\documentclass{webfiles}.}
\fi
%</main>
%    \end{macrocode}
%  
%
%    \chap Options.
%
%    The package options may be used in the optional argument of the
%    \verb=\usepackage= command, or in the optional argument of the
%    \verb=\webfile= command. In the second case, they only apply to
%    a single web.
%    We keep track of the choices with logical variables and a count
%    register, each having a global and a local variant.
%
%    \begin{macros}{\ifxwebIndex,\ifxwebRef,\ifxwebRagged,
%        \ifxwebHideFormats,\ifxwebCon,\xweb_hypertype}
%    \begin{macrocode}
%<*main>
\newif\ifxweb_GlobalIndex \newif\ifxwebIndex
\newif\ifxweb_GlobalRef    \newif\ifxwebRef
\newif\ifxweb_GlobalRagged \newif\ifxwebRagged
\newif\ifxweb_GlobalOC
\newif\ifxweb_GlobalHideFormats \newif\ifxwebHideFormats
\newif\ifxweb_GlobalCon    \newif\ifxwebCon
\DeclareOption{index}{\xweb_GlobalIndextrue}
\DeclareOption{noindex}{\xweb_GlobalIndexfalse}
\DeclareOption{reflist}{\xweb_GlobalReftrue}
\DeclareOption{noreflist}{\xweb_GlobalReffalse}
\DeclareOption{raggedbottom}{\xweb_GlobalRaggedtrue}
\DeclareOption{flushbottom}{\xweb_GlobalRaggedfalse}
\DeclareOption{onlychanges}{\xweb_GlobalOCtrue}
\DeclareOption{allsections}{\xweb_GlobalOCfalse}
\DeclareOption{nocon}{\xweb_GlobalConfalse}
\DeclareOption{contents}{\xweb_GlobalContrue}
\DeclareOption{hideformats}{\xweb_GlobalHideFormatstrue}
\DeclareOption{showformats}{\xweb_GlobalHideFormatsfalse}

\newcount\xweb_hypertype
\newcount\xweb_GlobalHypertype
\DeclareOption{hyperref}{\xweb_GlobalHypertype=1}
\DeclareOption{pdftex}{\xweb_GlobalHypertype=2 \input pdfcolor}
\DeclareOption{nohype}{\xweb_GlobalHypertype=0}

\newcounter{xwebLopDepth}  \setcounter{xwebLopDepth}{9}
\newcounter{xwebOutlineDepth}  \setcounter{xwebOutlineDepth}{9}
\DeclareOption{nofiles}{\c@xwebLopDepth=-9}
\DeclareOption{writefiles}{\c@xwebLopDepth=9}
\ExecuteOptions{index,reflist,raggedbottom,allsections,%
                contents,showformats,nohype,writefiles}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%  
%  
%  \iffalse
%   subdocument: The interface between CWEAVE and TeX
%  \fi
%  \input cweave-f-spec
%  
%  
%  
%    \chap Processing states.
%    
%    We have to typeset five different categories of material:
%    Documentation, program pieces---embedded within the documentation and
%    as large chunks, \TeX{} material within program pieces (i.e., comments
%    and refinement names), and cross reference information. Since we need
%    a complete other environment for the program pieces than for the rest
%    we design ``states'' where we switch to appropriately.
%     %
%    \begin{enumerate}
%    
%    \item A section starts in the {\it documentation state}.
%    
%    \item |\B| switches to {\it program state}. This can happen in
%    documentation and program state.
%    
%    \item While we process the argument of |\PB| we're in \emph{restricted
%    program state}; |\PB| may appear in documentation and in \TeX{}
%    state. Since \TeX{} state can be switched on within restricted
%    program state, |\PB| can appear within the argument of itself.
%    
%    \item In the arguments of |\C|, |\SHC|, and |\X| we switch to
%    {\it \TeX{} state}. All these cseqs appear only in (restricted)
%    program state, their official names are actually different. I.e., only
%    in (restricted) program state these cseqs are bound to the meaning
%    described here.
%    
%    \item Cross reference information are attached to most sections with
%    refinements. This information is processed in {\it CR state}.
%    After CR state material
%    comes always the next section or the document end, i.e., material in
%    documentation state.
%    
%    \end{enumerate}
%     %
%    This FSA is illustrated by the diagram in figure~\ref{fig:fsa}.
%  
%    \begin{figure}
%    
%    \begin{center}
%    \chardef\\=`\\
%    \input{cweb-fsa.latex}
%    \end{center}
%    
%    \caption{The processing state's FSA. The automaton starts and ends in
%    the ``documentation'' state.}
%     \label{fig:fsa}
%    
%    \end{figure}
%  
%    \begin{sloppypar}
%     |\xweb_documentation| will switch to documentation state,
%     |\xweb_program| to program state, |\xweb_Rprogram| to restricted
%     program state, |\xweb_tex| to \TeX{} state, and |\xweb_CR| to CR state.
%     If we're already in a state, the switch to this state shall be a
%     permissible null operation.
%    \end{sloppypar}
%    
%    
%    \sect The basic difference between these states can be named with
%    two parameters: (1)~The cseq bindings in effect and (2)~the layout
%    parameters used for paragraph makeup.
%    
%    In (restricted) program state and in CR state the text is output
%    under the control of \cweave{}, and tagged by \cweave{}. The used
%    tags are from a global namespace and should only be in effect during
%    these states. We call this tag set the \emph{CWEAVE bindings}. In the
%    other two states the tags are largely defined by the user, the tag
%    set is called the \emph{user bindings}. The switch to another binding
%    is always done locally, i.e., if we switch from documentation to
%    restricted program state within a group we don't have to bother about
%    the restauration of the user binding; it will be done automatically
%    by \TeX{} at the end of the group. Nevertheless we must be able to
%    switch from the \cweave{} bindings back to the user bindings which
%    were in effect when we activated the \cweave{} bindings. This is
%    needed for the \TeX{} state which is always activated within
%    (restricted) program state.
%    
%    The parameters for \emph{program layout} are really special ones
%    since they need to support the indentation which shows the program
%    structure. These parameters are used in program and in \TeX{} state.
%    The \emph{document layout} parameters established by the user are
%    used in the other three states.
%  
%    The following table shall summarize this. $C$~denotes \cweave{}
%    bindings, $U$~user bindings, $P$~program layout, and $D$~document
%    layout. If an entry is empty, its value is not changed on entry in
%    this state.
%
%    \begin{quote}\rm
%    \begin{tabular}{rIcIc}
%    \multicolumn1{cI}{\sc State} & \sc Binding & \sc Layout \\[1pt]
%    \hline
%    documentation & $U$ & $D$ \\
%    program & $C$ & $P$ \\
%    restricted program & $C$ & \\
%    \TeX{} & $U$ & \\
%    CR & $C$ & $D$ \\
%    \end{tabular}
%    \end{quote}
%  
%  
%    \sect Since the user bindings and the document layout is defined
%    initially, we don't have to do anything if it's requested. Only if we
%    change it, i.e., within |\xweb_CweaveBindings| and
%    |\xweb_ProgramLayout|, we redefine |\xweb_UserBindings| and
%    |\xweb_DocLayout|. If they are eventually executed, they shall
%    rebind themselves back to |\relax|. This way we can switch to
%    documentation state as often as we want.
%
%    \begin{macros}{\xweb_UserBindings,\xweb_DocLayout,
%         \xweb_documentation,
%         \xweb_Rprogram,\xweb_program,\xweb_tex,\xweb_CR}
%    \begin{macrocode}
%<*main>
\let\xweb_UserBindings=\relax
\let\xweb_DocLayout=\relax
\def\xweb_documentation{%
   \xweb_UserBindings
   \xweb_DocLayout}
\def\xweb_Rprogram{%
   \xweb_CweaveBindings}
\def\xweb_program{%
   \xweb_CweaveBindings
   \xweb_ProgramLayout}
\def\xweb_tex{%
   \xweb_UserBindings}
\def\xweb_CR{%
   \xweb_CweaveBindings
   \xweb_DocLayout}
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%    \chap Saving and restoring control sequences.
%    
%    We have a lot of cseqs which are defined within the namespace of this
%    package and which will be used with other names. This usage is in a
%    controlled environment, namely neither in documentation nor in \TeX{}
%    state. (I.e., the text processed is tagged by \cweave{}, not by humans;
%    therefore we have a precise specification of the cseqs we have to
%    accept.) We cannot work with groups where a cseq is just redefined
%    and \TeX{} takes care for establishing the old binding again; when we
%    switch from program state to \TeX{} state all the bindings which were
%    in effect before the program state got active, i.e., in the
%    documentation state, must be in effect again. We cannot simply
%    consider the \TeX{} state as something parallel to program state, it
%    must be a hierarchical relationship: In the program state values are
%    set up which must be available after switching back from \TeX{} to
%    program state.
%    
%    We save the current binding of a cseq in another cseq, but only if
%    there exists a binding currently. This is done to save valuable
%    \TeX{} main memory. Actually, one
%    can assume that nearly no cseq bindings must be saved at all---the
%    used names are strange enough. The bindings of |\foo|, i.e., of the
%    cseq with the name \fbox{\tt foo}, is saved as the cseq with the name
%    \fbox{\tt xweb\_s\_\char `\\ foo}, i.e., as
%      |\csname xweb\_s\_\string\foo\endcsname|.
%    
%    
%    \sect The save process is not done statically, but by the macro
%    |\xweb_rebind| which interprets a list of tuples $({\it old\_name},
%    {\it new\_name})$, terminated by the tuple $(|\stop|, |\stop|)$.
%    Eventually it constructs two new lists, |\xweb_ToRestore| with the
%    cseqs which had a binding, and |\xweb_undefined| with the names which
%    didn't have one.
%    
%    The saving is actually done by |\xweb_SaveBinding|, |\xweb_rebind|
%    is responsible for the initialization, |\xweb_DoRebind| for the
%    effective rebinding and the tail recursion on the list.
%  
%    \begin{fixme}
%       We could pull the |\next| assignment in the |\else| branch out
%       of the loop to get a better performance. Should measure if
%       this is of interest.  
%    \end{fixme}
%
%    \begin{macros}{\xweb_undefined,\xweb_ToRestore,\xweb_rebind,
%        \xweb_DoRebind}
%    \begin{macrocode}
%<*main>
\newtoks\xweb_undefined
\newtoks\xweb_ToRestore
\def\xweb_rebind{%
    \xweb_undefined{}%
    \xweb_ToRestore{}%
    \xweb_DoRebind
    }
\def\xweb_DoRebind#1#2{%
    \ifx #1\stop
       \let\next\relax
    \else
        \xweb_SaveBinding #2%
        \let #2=#1%
        \let\next\xweb_DoRebind
    \fi
    \next
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%    \sect If the cseq to be saved is undefined, it may just be added to
%    the ``undefined list.'' Otherwise its binding is saved and it's added
%    to the ``to-be-restored list.''
%    
%    \TeX{}nical note: The cseq-name for the saved binding must be created
%    before the |\let| is executed.
%
%    \begin{macro}{\xweb_SaveBinding}
%    \begin{macrocode}
%<*main>
\def\xweb_SaveBinding#1{%
    \ifx #1\undefined
        \xweb_undefined \expandafter{\the\xweb_undefined #1}%
    \else
        \expandafter\let \csname xweb_s_\string#1\endcsname =#1%
        \xweb_ToRestore \expandafter{\the\xweb_ToRestore #1}%
    \fi
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%    
%  
%    \sect The restoration of rebound cseqs is a two-tied activity: All
%    previously undefined cseqs must be made undefined again, and all saved
%    cseqs must be restored. Actually, we don't need to reset the two token
%    lists, but we do it to save space.
%    
%    Both |\xweb_undefine| and |\xweb_RestoreBinding| iterate over a list
%    of cseqs terminated by |\stop|.
%    
%    \begin{fixme}
%      And here the |\next| assignment could be prepended to the loop as
%      well.
%    \end{fixme}
%
%    \begin{macros}{\xweb_RestoreBindings,\xweb_undefine}
%    \begin{macrocode}
%<*main>
\def\xweb_RestoreBindings{%
    \expandafter\xweb_undefine \the\xweb_undefined \stop
    \xweb_undefined{}%
    \expandafter\xweb_RestoreBinding \the\xweb_ToRestore \stop
    \xweb_ToRestore{}%
    }
\def\xweb_undefine#1{%
    \ifx #1\stop
        \let\next\relax
    \else
        \let#1\undefined
        \let\next\xweb_undefine
    \fi
    \next
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect \TeX{}nical note: As in |\xweb_SaveBinding|, the cseq-name for
%    the saved binding must be created before the |\let|s are executed.
%    
%    \begin{fixme}
%        Another |\next| assignment.
%    \end{fixme}
%
%    \begin{macro}{\xweb_RestoreBinding}
%    \begin{macrocode}
%<*main>
\def\xweb_RestoreBinding#1{%
    \ifx #1\stop
        \let\next\relax
    \else
        \expandafter\let \expandafter#1\csname xweb\string#1\endcsname
        \expandafter\let \csname xweb_s_\string#1\endcsname \undefined
        \let\next\xweb_RestoreBinding
    \fi
    \next
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%  
%
%    \chap Hyperlinks.
%
%    Because at least two implementations of hyperlinks are supported,
%    it is most convenient to define private macros for
%    hyperlinks and hypertargets. Their definition depends on
%    |\xweb_hypertype| and must therefore be performed as part
%    of the |\webfile| command, after the options are processed.
%    (This is more efficient than testing |\xweb_hypertype| again for
%    each link.)
%
%    The anchor name depends on the current value of the |xwebModule|
%    counter; this value must be set before |\xweb_hyperlink| or
%    |\xweb_hypertarget| is used.
%
%    \begin{macros}{\xweb_anchor,\xweb_SetupHrefs,
%        \xweb_hlink,\xweb_htarget}
%    \begin{macrocode}
%<*main>
\def\xweb_anchor{xwebmod:\xwebJobname:\arabic{xwebModule}}
\def\xweb_SetupHrefs{
   \ifnum\xweb_hypertype=0
      \def\xweb_hlink##1{##1}
      \def\xweb_htarget##1{##1}
   \else\ifnum\xweb_hypertype=1
      \def\xweb_hlink##1{\hyperlink{\xweb_anchor}{##1}}
      \def\xweb_htarget##1{\hypertarget{\xweb_anchor}{##1}}
   \else\ifnum\xweb_hypertype=2
      \def\xweb_hlink##1{\xweb_pdflink{\xweb_anchor}{##1}}
      \def\xweb_htarget##1{\xweb_pdftarget{\xweb_anchor}{##1}}
   \else\PackageError{webfiles}{This can't happen.}{%
      this may be a bug in the webfiles package}
   \fi\fi\fi}
\xweb_SetupHrefs
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \chap PDF\TeX\ support.  PDF\TeX\ is an implementation of \TeX\
%    that has the ability to output pdf instead of dvi. It has some
%    extra primitives, that control pdf-specific things, such as
%    hyperlinks, colours, and `outlines'.
%
%    
%    \sect The outline is a kind of table of contents, that is always
%    present at the left side of the pdf reader window (if the user
%    wishes so). Web documents and main sections get outline entries.
%
%    \begin{macro}{\xwebPDFOutline}
%    \begin{macrocode}
%<*main>
\def\xwebPDFOutline#1#2{{%
      \edef\tmpnr{#1}%
      \edef\name{#2}%
      \c@xwebModule=\tmpnr\relax
      \ifnum\xweb_hypertype=2
          \edef\anchor{\xweb_anchor}
          \pdfoutline goto name{\anchor}{#1 \name}
      \fi}}
%</main>
%    \end{macrocode}
%    \end{macro}
%    
%
%    \sect  PDF links are implemented using code copied from
%    \texttt{pdfcwebmac.tex}, with fixes from Andreas Scherer. The
%    raised |\hbox| is to ensure that the top line of the module will
%    be entirely visible. It must be |\smash|ed to avoid spurious
%    vertical material.
%
%    \begin{macros}{\xweb_pdflink,\xweb_pdftarget}
%    \begin{macrocode}
%<*main>
   \def\xweb_pdflink#1#2{%
       \pdfannotlink
          attr{/Border [0 0 0]}
          goto name{#1}
          \Blue #2\Black
       \pdfendlink}
   \def\xweb_pdftarget#1#2{
       \smash{\raise\baselineskip\hbox to 0pt{\pdfdest name{#1} fith}}
       #2}
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%    
%    \chap Sections.
%  
%    We distinguish between main sections with titles which start a group
%    of sections and normal (untitled) sections within a group.
%    All sections are numbered sequentially by \cweave.
%    The section numbers are output in boldface at the very start of a
%    section, followed by a dot and a quad. The changeflag is a star
%    lapping to the right.
%
%    \begin{macro}{\xwebLapStar}
%    \begin{macrocode}
%<*main>
\def\xwebLapStar{\rlap{*}}
%</main>
%    \end{macrocode}
%    \end{macro}
%    
%  
%    \sect Important main sections are (optionally) started on a new
%    page, normal sections 
%    have approximately two picas vertical space in front. The very first
%    main section does not automatically start on a new page since a title
%    may be in front of it.
%    
%    The user may also add a ``level'' to the title of a main section. 
%    A newpage is inserted before a section if its level is smaller than the
%    value of the counter |xwebSecNoEject| which has default value~3.
%    And we will pay attention to this group level when
%    we create a table of contents.
%  
%    The title of a main section is set as a heading after the section
%    number, also in bold face. The first paragraph of the following
%    documentation has no indentation. The documentation part of normal
%    sections is run in after the section number.
%
%    \begin{macros}{\xwebGroupLevel,xwebSecNoEject}
%    \begin{macrocode}
%<*main>
\newcount\xwebGroupLevel
\newcounter{xwebSecNoEject}
        \setcounter{xwebSecNoEject}{3}
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%    
%    \sect The section number that is supplied by \cweave\ is used to
%    set the counter |xwebModule|.
%    This is necessary because the section numbers
%    can be non-sequentially, for example, if only changed sections are
%    printed, or if an excerpt from a web is taken. By using a
%    counter, the appearance of the number is made changeable in the
%    normal \LaTeX\ way through redefinition of |\thexwebModule|.
%    The number can contain a star, to indicate that the section is
%    changed by a changefile.
%    In that case, |\ifon| is made |true|; else it will be |\maybe|, and
%    by redefining |\maybe| the user can decide wether non-changed sections
%    should be printed. The default behaviour is to print them.
%    This weird interface is copied from the plain version, but this 
%    package adds a friendlier interface.
%
%    This is all implemented in the macro |\xweb_PrepareSection|, which
%    is used before each section.
%    This macro also changes to documentation state.
%
%    \begin{macros}{xwebModule,\ifon,\onmaybe,\maybe,
%       \xweb_PrepareSection,\xweb_secno,\*,\xweb_star}
%    \begin{macrocode}
%<*main>
\newcounter{xwebModule}
\newif\ifon % determines if the section is `on'
\def\onmaybe{\let\ifon=\maybe} % analogous to \ontrue
\let\maybe=\iftrue  % initial meaning; the user can say "\let\maybe=\iffalse"
\def\xweb_PrepareSection#1{%
   {\xdef\secstar{#1}%
    \let\*=\empty%  remove \* from the number
    \xdef\xweb_secno{#1}}
   \ifx\xweb_secno\secstar % if they are the same; i.e.: 
      \onmaybe                  % if there was no star in #1
      \xdef\xweb_star{}%
   \else
      \ontrue
      \xdef\xweb_star{*}%
   \fi
    \setcounter{xwebModule}{#1}% global set!
    \xweb_documentation
}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect Every web section is contained in a |xwebModule|
%    environment. This environment takes care of vertical space before
%    the section, optional page breaks, setting the section number,
%    and initializing the |\everypar| token register.
%
%    |\everypar| must make |\@noskipsec| false, to indicate that the
%    first paragraph of the documentation part has been processed.
%    We have to initialize it ourselves, because there is no
%    |\section| to do it.  
%    |\Y| and |\B| use |@noskipsec| to decide if there must be a |\par|
%    before the program part. 
%
%    The current reference, |\@currentlabel|, is set to the web
%    section.
%
%    If |\xwebRaggedtrue|, the user has specified that sections should
%    preferably not be broken across pages, so every section will be
%    finished with optional vertical space and a negative penalty.
%    Else, just the negative penalty is inserted to indicate that this
%    is a good place for a page break.
%
%    The module is typeset in a |\vbox| that is |\unvbox|ed at the end
%    of the environment. This way, the output routine cannot fire
%    while \TeX\ is processing a program text, and no name conflicts
%    can arise even when the weave bindings are in effect. Thanks to
%    Hans Hagen for the idea. ---No, we can't do it this way. The
%    documentation part cannot generate floats if it's in a vbox. Only
%    the program part should be vboxed and unvboxed, but this is more
%    difficult. Must think about it.
%
%    The module is also the target for hyperlinks, using |\xweb_htarget|.
%    (This macro is defined to produce only its second argument if the
%    hyperref package is not in use.)
%
%    If it is the first module, the table of contents is set
%    first. By setting the table of contents when the first module is
%    found, we allow the user to change |\xwebContentsTop| etc.~in the
%    limbo section.
%
%    \begin{macros}{\thexwebModule,\xweb_ModBox,\ifxweb_FirstModule,
%                   \xwebModuleHook}
%    \begin{environment}{xwebModule}
%    \begin{macrocode}
%<*main>
\def\thexwebModule{\arabic{xwebModule}}
\newbox\xweb_ModBox
\newif\ifxweb_FirstModule \xweb_FirstModulefalse
\newenvironment{xwebModule}{%
   \ifxweb_FirstModule
      \ifxwebCon\xwebContents{\xwebJobname}\fi
      \global\xweb_FirstModulefalse
      \openout\xweb_cont=\xwebJobname.con
      \write\xweb_cont{\catcode `\noexpand\@=11\relax}%
   \fi
   \ifxwebRagged\vfil\penalty-200\vfilneg%  (TeXbook p.353)
                                   % (this is a \filbreak without a \par)
   \else\penalty-200\fi
   %\setbox\xweb_ModBox=\vbox\bgroup
   \edef\@currentlabel{\thexwebModule}
   \par\bigskip
   \everypar{%
      \if@noskipsec%
         \global\@noskipsecfalse%
         \everypar{\penalty-100}%
      \fi}
   \@noskipsectrue
   \mbox{}\hspace{-\parindent}%
   \xwebModuleHook
   \xweb_htarget{\textbf{\thexwebModule.}\xweb_star}% typeset module number
   \hskip 1em plus0.1em minus 0.1em%
   }{%\egroup\unvbox\xweb_ModBox
   }
\def\xwebModuleHook{}
%</main>
%    \end{macrocode}
%    \end{environment}
%    \end{macros}
%  
%    
%    \sect The main sections are started with the macro |\N|. 
%    The parameters are:
%    \begin{description}
%    \item{|#1|:} a number denoting the ``group level'' of the main
%      section, titles of main sections with lower numbers should be
%      presented more prominently in the table of contents.
%    \item{|#2|:} the section number.
%    \item{|#3|:} the title of the section
%      group. This last parameter must be terminated by a dot.
%    \end{description}
%    The group level must be passed to the macros that format the table
%    of contents. Since there is no easy place predetermined by \LaTeX{}
%    for such a wish we use a trick: The entry text for the table of
%    contents first sets the count register |\xwebGroupLevel| with the
%    respective level---this register may be tested after a pro-forma
%    evaluation of the entry.
%
%    When writing to the \texttt{.con} file, we have to use
%    |\@unexpandable@protect|; else there will be trouble with
%    insertion of |\xweb_ModTitle| in the contents file.
%  
%    We tell the user that we have reached the next starred section.
%    The message is output after the section header is set, it shall be on
%    the correct page. Since the token list to be output is expanded at
%    shipout time, we must take care for the immediate expansion ourselves.
%
%    A newpage is inserted if the level of the section is smaller than
%    the |xwebSecNoEject| counter and it is not the first section (if
%    the user wants the web document to begin on a new page, he can
%    insert a newpage himself).
%
%    \begin{macros}{\N,\xwebMainSecSkip}
%    \begin{macrocode}
%<*main>
\def\xwebMainSecSkip{\clearpage}
\def\N#1#2#3.{%
    \ifon\end{xwebModule}\fi
    \global\xwebGroupLevel #1                   % <-- space!!
    { \let\*=\empty%
      \xdef\xweb_secno{#2}% get the section number
    }%
    \ifnum\xweb_secno>1
       \ifnum \xwebGroupLevel<\c@xwebSecNoEject
          \xwebMainSecSkip
       \fi
    \fi
    \message \expandafter{*\xweb_secno}%
    \xweb_PrepareSection{#2}
    \ifon
       \def\xweb_ModTitle{#3}%
       \begin{xwebModule}{\textbf{#3.}}% title
       \hskip 1em plus.1em minus.1em%
       \ifnum\c@xwebLopDepth > #1%
          \addcontentsline{lop}{starred}{%
          \protect\global\xwebGroupLevel #1 %  space after #1 !
              {\thexwebModule.}~{#3}}%
          {   \let\protect\@unexpandable@protect
              \edef\next{\write\xweb_cont{%
                \ZZ{#3}{#1}{\xweb_secno}{\thepage}}}%
              \next 
          }%  write "\ZZ{title}{depth}{sec}{page}" to .con file
       \fi
       \ifnum\c@xwebOutlineDepth > #1%
          \xwebPDFOutline{\xweb_secno}{#3}% args: nr, title       
       \fi
}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%  
%    \sect Normal sections are started with |\M|.
%    
%    \begin{macro}{\M}  
%    \begin{macrocode}
%<*main>
\def\M#1{%
    \ifon\end{xwebModule}\fi
    \xweb_PrepareSection{#1}%
    \ifon\begin{xwebModule}%
      \ifnum\c@xwebLopDepth>9%
         \addcontentsline{lop}{xwebsection}{%
             \protect\global\xwebGroupLevel 4 \thexwebModule.}%
         {   \let\protect\@unexpandable@protect
             \edef\next{\write\xweb_cont{%
               \ZZ{}{4}{#1}{\thepage}}}%
             \next 
         }% write "\ZZ{title}{depth}{sec}{page}" to .con file
      \fi
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%  
%  
%  
%  
%  
%    \chap The List of Programs.
%
%    \begin{macro}{\listofprograms}
%    The ``List of Programs'' is like the ``List of Figures'' or the ``List
%    of Tables'', which are defined in the document class.
%    The following definition is copied, with the necessary changes, from 
%    |article.sty|,  16-Mar-88. It defines |\listofprograms| which is
%    used like |\listoffigures|. 
%
%    \begin{macros}{\xwebTocName,\xwebLopName}
%    \begin{macrocode}
%<*main>
\def\xwebTocName{Contents of \xwebJobname}
\def\xwebLopName{List of Programs}
\ifx\listofprograms\undefined
   \ifx \chapter\undefined  
       \def\listofprograms{\section*{\xwebLopName\@mkboth
       {\uppercase{\xwebLopName}}{\uppercase{\xwebLopName}}}\@starttoc{lop}}
   \else
       \newcommand{\listofprograms}{\chapter*{\xwebLopName\@mkboth
       {\uppercase{\xwebLopName}}{\uppercase{\xwebLopName}}}\@starttoc{lop}}
    \fi
\fi
%</main>
%    \end{macrocode}
%    \end{macros}
%    \end{macro}
%
%    
%    \sect Entries for the |.lop| file are generated with
%    |\addcontentsline| by the following commands: 
%  
%    \begin{itemize}
%    \item |\webfile| produces a |program| entry
%    \item |\N| produces a |starred| entry
%    \item |\M| produces a |xwebsection| entry
%    \end{itemize}
%  
%    \noindent
%    Program names are typeset with |\xweb_TTLopLine|, which sets
%    in large typewriter type:
%
%    \begin{macro}{\l@program}
%    \begin{macrocode}
%<*main>
\def\l@program#1{%
     \xwebGroupLevel\z@         % default value of group level
     \begingroup
         \let\numberline\@gobble        % width not known yet
         \setbox\z@ \hbox{#1}%
     \endgroup
     \xweb_TTLopLine{#1}%
}
%</main>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect Normal sections are hardly ever mentioned in the list,
%    but it will be possible. The entry consists of the number only,
%    as they have no title.
%
%    \begin{macro}{\l@xwebSection}
%    \begin{macrocode}
%<*main>
\def\l@xwebSection#1{
     \xwebGroupLevel\z@ % default value of group level
     \begingroup
         \let\numberline\@gobble        % width not known yet
         \setbox\z@ \hbox{#1}%
     \endgroup
     \xweb_NormalTocLine{#1}%
 }
%</main>
%    \end{macrocode}
%    \end{macro}
%  
%
%    \sect  Titles of main sections might have an associated group level
%    that determines how they are featured in the table. Titles on group
%    level~0 are typeset boldface, other titles in roman. 
%    They are indented proportionally to the group level, with
%    a basic indentation of |\xwebLopIndent|. 
%    An entry on group level~1 is not indented, the different layout
%    suffices as a distinction to level~0.  
%    The counter |\xwebLopIndentMaxLevel| constitutes an upper limit for
%    a recognized group level (concerning indentation, that is).
%
%    \begin{macros}{\xwebLopIndent,\xwebLopIndentMaxLevel}
%    \begin{macrocode}
%<*main>
\newdimen\xwebLopIndent
     \xwebLopIndent=2em
\newcount\xwebLopIndentMaxLevel
     \xwebLopIndentMaxLevel=4   % group level <= max level
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%    \sect The group level is specified within the entry name, i.e., in the
%    first argument to |\l@starred|. If this argument is evaluated,
%    |\xwebGroupLevel| might be set to the respective value. If it is
%    not set, an explicit invocation of |\addcontentsline|
%    is responsible for this entry. Then we assume that the group level
%    is~0.
%
%    \begin{macro}{\l@starred}
%    \begin{macrocode}
%<*main>
 \def\l@starred#1{%             % page will be processed later
     \xwebGroupLevel\z@         % default value of group level
     \begingroup
         \let\numberline\@gobble        % width not known yet
         \setbox\z@ \hbox{#1}%
     \endgroup
     \ifnum \xwebGroupLevel=\z@
         \let\next\xweb_BoldTocLine
     \else
         \let\next\xweb_NormalTocLine
     \fi
     \next{#1}}
%</main>
%    \end{macrocode}
%    \end{macro}
%    A |\next| assignment is needed here, because the macro is
%    actually called with 2 arguments; the second is used by 
%    |\@dottedtocline| and such, so a |\fi| after the expansion
%    is not allowed.
%
%    
%    \sect A normal line has an indentation of $(l-1) \cdot {\it
%    toc\_indent}$, where $l = \min({\it group\_level},
%    {\it max\_level})$.
%  
%    The first argument of |\@dottedtocline| is used to specify a
%    depth of the issued entry. All entries with a depth larger than
%    |tocdepth| are discarded! So we always specify level 1, as the
%    level doesn't matter to \LaTeX\ and no entry is to be discarded.
%
%    \begin{macro}{\xweb_NormalTocLine}
%    \begin{macrocode}
%<*main>
\def\xweb_NormalTocLine#1{%     % page will be processed later
    \ifnum \xwebGroupLevel>\xwebLopIndentMaxLevel
        \xwebGroupLevel\xwebLopIndentMaxLevel
    \fi
    \advance\xwebGroupLevel\m@ne        % group level -= 1
    \@dottedtocline
            % \xwebGroupLevel                   % level (old)
            1                                   % level
            {\xwebGroupLevel\xwebLopIndent}%    % basic indent
            \xwebLopIndent                      % numwidth
            {#1}%                               % entry
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%  
%  
%  
%    \sect A bold line is typeset like a normal line, only the entry
%    is typeset in bold.
%
%    \begin{macro}{\xweb_BoldTocLine}
%    \begin{macrocode}
%<*main>
\def\xweb_BoldTocLine#1{%
    \@dottedtocline
            1                                   % level
            {\xwebGroupLevel\xwebLopIndent}%    % basic indent
            \xwebLopIndent                      % numwidth
            {{\bf #1}}%                         % entry
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%  
%  
%    \sect A |xweb@tt_lop_line| is like a |cweb@bold_toc_line| in the
%    |cweb| style:  
%    It has no dots, but the entry is typeset in large typewriter type,
%    instead of 
%    bold roman.
%
%    \begin{macro}{\xweb_TTLopLine}
%    \begin{macrocode}
%<*main>
\def\xweb_TTLopLine#1#2{%
    \addpenalty{\@secpenalty}%
    \addvspace{2em plus\p@}%
    \begingroup
        \noindent 
        \hangindent\xwebLopIndent
        \rightskip\@tocrmarg  \parfillskip -\rightskip
        \interlinepenalty\@M
        \@tempdima\xwebLopIndent        % for \numberline
        {\large\bf\tt #1}\nobreak\hfill \hbox to\@pnumwidth{\hss #2}%
        \par
    \endgroup
    \addvspace{.5em plus\p@}%
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%  
%  
%  
%  
%    \chap Typesetting programs.
%    
%    Program pieces come in two flavours: as argument of |\PB|, or as
%    material after |\B|. In the former case we can use a group for the
%    switch to the restricted program state, the group end will restore the
%    previous state again. In the latter case we use |\B| for the switch to
%    program state, the cross reference list or the next section will go to
%    another state. Since we have to do more for the material after |\B|,
%    we define this cseq later.
%
%    \begin{macro}{\PB}
%    \begin{macrocode}
%<*main>
\def\PB#1{%
    \begingroup
        \xweb_Rprogram
        \leavevmode
        #1%
    \endgroup}
%</main>
%    \end{macrocode}
%    \end{macro}
%    
%  
%    \sect Note, that |\Y| cannot just be |\smallskip|, as in the plain
%    version. We must assert that the current paragraph is ended before
%    the vertical glue is inserted, and that's not done by the \LaTeX{}
%    definition of |\smallskip|. In addition we add some negative penalty,
%    here is a good place for a page break. As the penalty value we use
%    half the section break penalty---of course a section start is an even
%    better place for a page break\,\dots
%    
%    It might be that |\Y| is the very first token in a ``normal''
%    section. Then the section number isn't set already since it is to be
%    run-in. In that case we don't set the vertical skip but simply start
%    the section with the program part.
%    
%    \TeX{}nical note: The flag |@noskipsec| may be used to test if we're
%    immediately after a run-in section heading.
%
%    \begin{macros}{\xwebProgPenalty,\Y}
%    \begin{macrocode}
%<*main>
\newcount\xwebProgPenalty
        \xwebProgPenalty=\@secpenalty
        \divide\xwebProgPenalty by 2
\def\Y{%
    \if@noskipsec
    \else
        \par
        \penalty\xwebProgPenalty
        \smallskip
    \fi}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect Yep, let's unfold the ``official'' names of the cseqs used in
%    program state.
%    
%    If we turn on the \cweave{} bindings, they might be in effect already,
%    we don't need to establish them again. We can test
%    |\xweb_UserBindings| for this case, it will be redefined then.
%
%    \errorcontextlines=20
%    \begin{macros}{\xweb_CweaveBindings,\xweb_UserBindings,
%       \1,\2,\3,\4,\5,\6,\7,\8,\?,\AND,\CM,\DC,\E,\G,\GG,\I,\K,
%       \LL,\MOD,\NULL,\R,\OR,\PA,\this,\V,\W,\XOR,\Z,\MG,\MGA,
%       \MM,\PP,\.,\T,\MRL,\C,\SHC,\X,\ATH,\D,\F,\J,
%       \vb,\*,\A,\As,\Q,\Qs,\U,\Us,\ET,\ETs,\)}
%    \begin{macro}{\\}
%    \begingroup\catcode`\&=12 \catcode`\|=12
%      \begin{macro}{\&}
%      \begin{macro}{\|}
%    \endgroup
%    \begin{macrocode}
%<*main>
\def\xweb_CweaveBindings{%
    \ifx \xweb_UserBindings\relax
        \xweb_rebind
            % indentation and paragraph layout
            \xweb_IncrIndent    \1%
            \xweb_DecrIndent    \2%
            \xweb_ExprBreak     \3%
            \xweb_backup        \4%
            \xweb_OptBreak      \5%
            \xweb_break         \6%
            \xweb_BigBreak      \7%
            \xweb_noindent      \8%
            % C/C++ tokens
            \xwebRel               \?%
            \xwebAddress           \AND
            \xwebComplement        \CM
            \xwebScope             \DC
            \xwebEquiv             \E
            \xwebGe                \G
            \xwebRightShift        \GG
            \xwebNe                \I
            \xwebAssign            \K
            \xwebLeftShift         \LL
            \xwebMod               \MOD
            \xwebNull              \NULL
            \xwebNot               \R
            \xwebBinOr             \OR
            \xwebMemberRef         \PA
            \xwebThis              \this
            \xwebOr                \V
            \xwebAnd               \W
            \xwebXor               \XOR
            \xwebLE                \Z
            \xwebPointer           \MG
            \xwebPointerMemberRef  \MGA
            \xwebDecr              \MM
            \xwebIncr              \PP
            % more tokens
            \xwebId             \\%
            \xwebIdLetter       \|%
            \xwebRes            \&%
            \xwebString         \.%             %% ( ...Emacs...
            \xwebStringBreak    \)%
            \xwebNumber         \T
            \xwebCombinedOp     \MRL
            % goes to TeX state
            \xwebComment        \C
            \xwebCxxComment     \SHC
            \xwebRefName        \X
            % CWEB tokens
            \xwebMacrosHere     \ATH
            \xwebDefine         \D
            \xwebFormat         \F
            \xwebIdCat          \J
            \xwebVerbString     \vb
            % cross reference tags
            \xwebChangeFlag     \*%
            \xwebCRAlso         \A
            \xwebCRsAlso        \As
            \xwebCRCite         \Q
            \xwebCRsCite        \Qs
            \xwebCRUse          \U
            \xwebCRsUse         \Us
            \xwebCREt           \ET
            \xwebCRsEt          \ETs
            % finish the list
            \stop\stop
        \def\xweb_UserBindings{%
            \xweb_RestoreBindings
            \let\xweb_UserBindings\relax
            }%
    \fi
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macros}
%  
%    \sect Since most of the \cweave{} bindings are simple and tedious
%    coding, we'll have a look at the program layout next. Between two
%    paragraphs there must not be any skip, the skip used in document
%    layout is saved in |\xweb_SaveParskip|. A few other layout
%    parameters from the document layout must be saved as well.
%
%    \begin{macros}{\xweb_SaveParskip,\xweb_SaveRightskip,      
%		    \xweb_SaveSemSFCode,\xweb_SavePretolerance, 
%		    \xweb_SaveHyphenpenalty,\xweb_SaveExhyphenpenalty,
%                   \xweb_SaveDocLayout,\xweb_RestoreDocLayout}
%    \begin{macrocode}
%<*main>
\newskip\xweb_SaveParskip
\newskip\xweb_SaveRightskip
\newcount\xweb_SaveSemSFCode
\newcount\xweb_SavePretolerance
\newcount\xweb_SaveHyphenpenalty
\newcount\xweb_SaveExhyphenpenalty

\def\xweb_SaveDocLayout{%
    \xweb_SaveParskip\parskip
    \xweb_SaveRightskip\rightskip
    \xweb_SaveSemSFCode\sfcode`; % changed by \xweb_ProgramLayout
    \xweb_SavePretolerance\pretolerance
    \xweb_SaveHyphenpenalty\hyphenpenalty
    \xweb_SaveExhyphenpenalty\exhyphenpenalty
    }
\def\xweb_RestoreDocLayout{%
    \parskip\xweb_SaveParskip
    \rightskip\xweb_SaveRightskip
    \sfcode`;=\xweb_SaveSemSFCode
    \pretolerance\xweb_SavePretolerance
    \hyphenpenalty\xweb_SaveHyphenpenalty
    \exhyphenpenalty\xweb_SaveExhyphenpenalty
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect When |\xweb_ProgramLayout| is called for the very first time
%    we have to set up some variables. This cannot be done in advance
%    since they depend on values that might be changed by the user in the
%    preamble. This setup is done in |\xweb_LayoutInit|.
%    
%    If the program layout is already active, we must not switch it on
%    another time. This can be tested by the current binding of
%    |\xweb_DocLayout|.
%
%    \begin{macros}{\xweb_ProgramLayout,\xweb_DocLayout}
%    \begin{macrocode}
%<*main>
\def\xweb_ProgramLayout{%
    \ifx \xweb_DocLayout\relax
        \xweb_LayoutInit
        \xweb_SaveDocLayout
        \def\xweb_DocLayout{%
            \xweb_RestoreDocLayout
            \let\xweb_DocLayout\relax
            }%
        % set new values
        \parskip\z@skip
        \rightskip\z@ plus 100\p@ minus 10\p@
        \sfcode`;=3000          % same stretch factor as period.
        \pretolerance\@M
        \hyphenpenalty 9999     % strings can be broken this way
        \exhyphenpenalty\@M
    \fi
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect The unit of the basic indentation is stored in
%    |\xwebIndentUnit|. Continuation lines are indented two units further,
%    i.e., the initial hanging indentation is 3~units. The current hanging
%    indentation is kept in |\xweb_indent|.
%    
%    We need undiscardable items which can be used as backspaces, of one
%    and two units, respectively. This is done best by boxes. The
%    initialization of the boxes must be postponed until the user had the
%    chance to change |\xwebIndentUnit|, it's done in the program state
%    initialization.
%
%    \begin{macros}{\xwebIndentUnit,\xweb_indent,\xweb_bak,\xweb_bakk,
%                   \xweb_LayoutInit}
%    \begin{macrocode}
%<*main>
\newdimen\xwebIndentUnit   \xwebIndentUnit=1em
\newdimen\xweb_indent
\newbox\xweb_bak        % backspace one unit
\newbox\xweb_bakk       % backspace two units
\def\xweb_LayoutInit{%
    \global\setbox\xweb_bak \hbox to -1\xwebIndentUnit{}%
    \global\setbox\xweb_bakk \hbox to -2\xwebIndentUnit{}%
    \global\let\xweb_LayoutInit\relax
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect Now we can formulate how to start typesetting program pieces: We
%    switch to program state, set the initial indentation, and add the basic
%    indentation of the first code line.
%    
%    If the code line is the very first text to be typeset in this
%    section, we don't add the basic indentation---we're already indented
%    from the run-in section number. But we must not start our section
%    with |\noindent|, the section number would be typeset in the left
%    margin then. So we just
%    emulate an empty documentation part, the section number is now
%    correctly set. |\B| can test for this case: |@noskipsec| is still true
%    then.
%  
%    \begin{macro}{\B}
%    \begin{macrocode}
%<*main>
\def\B{%
    \if@noskipsec \hskip 1em \fi
    \xweb_program
    \xweb_indent 3\xwebIndentUnit  \hangindent\xweb_indent
    \ifvmode
         \if@noskipsec
            \indent             % add an empty documentation part
        \else
            \noindent \kern\xwebIndentUnit
        \fi
   \fi
}
%</main>
%    \end{macrocode}
%    \end{macro}
%    
%  
%    \sect If a statement is finished, a new paragraph with the basic
%    indentation has to be started.
%    
%    An optional statement break is implemented by a low penalty which
%    will be selected if the line has to be broken. We assume that the
%    hanging indentation of the new line is already set correctly, and
%    have to backup two units to get the basic indentation. It might be
%    that the line break is not chosen by \TeX{}, we compensate the
%    backspace for this case. This compensation is discarded at the start
%    of a new line.
%
%    \begin{macros}{\xweb_break,\xweb_ExprBreak,\xweb_BigBreak,
%                   \xweb_OptBreak}
%    \begin{macrocode}
%<*main>
\def\xweb_break{%       % forced break, between statements
    \ifmmode\else
        \endgraf        % in LaTeX it isn't sure what \par is really...
        \noindent
        \hangindent\xweb_indent  \kern\xweb_indent
        \copy\xweb_bakk % go back to basic indentation
        \ignorespaces
    \fi
    }
\def\xweb_OptBreak{%    % optional break between statements
    \hfil \penalty\m@ne
    \hfilneg  \kern .5em  \kern 2\xwebIndentUnit   % discarded on line break
    \copy\xweb_bakk
    \ignorespaces
    }
\def\xweb_BigBreak{%    % forced break and a little extra space
    \Y
    \xweb_break
    }
\def\xweb_ExprBreak#1{% % break with penalty #1 * 10
    \hfil \penalty#10
    \hfilneg            % discarded on line break
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect When we increment the indentation, we must not forget to set
%    the hanging indentation immediately since |\xweb_OptBreak| relies on
%    the new value. If a continuation line is needed it will also be
%    indented one unit more, which is ok since it should be distinguishable
%    from the next line.
%     %
%    \begin{fixme}  
%      Shouldn't the hanging indentation be set anew at the end of
%      |\xweb_DecrIndent| as well?
%    \end{fixme}
%
%    \begin{macros}{\xweb_IncrIndent,\xweb_DecrIndent,\xweb_backup,
%                   \xweb_noindent}
%    \begin{macrocode}
%<*main>
\def\xweb_IncrIndent{%
    \global\advance\xweb_indent\xwebIndentUnit
    \hangindent\xweb_indent
    }
\def\xweb_DecrIndent{\global\advance\xweb_indent -\xwebIndentUnit}
\def\xweb_backup{\copy\xweb_bak}
\def\xweb_noindent{%                            % no indentation
    \hskip -\xweb_indent \hskip 2\xwebIndentUnit
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%  
%    \chap Program (C or \C++) tokens.
%  
%    Since the user might want to change the (somewhat unusual) way some
%    of the operators are typeset, we supply names for them.
%
%    \begin{macros}{\xwebAnd,\xwebEquiv,\xwebGe,\xwebLE,
%                   \xwebNe,\xwebNull,\xwebNot,\xwebOr,\xwebXor}
%    \begin{macrocode}
%<*main>
\let\xwebAnd=\land              % logical and, &&
\let\xwebEquiv=\equiv           % equiv sign, for ==
\let\xwebGe=\ge                 % greater or equal
\let\xwebLE=\le                 % less or equal
\let\xwebNe=\ne                 % unequal, !=
\let\xwebNull=\Lambda           % NULL pointer
\let\xwebNot=\lnot              % logical not, !
\let\xwebOr=\lor                % logical or, ||
\let\xwebXor=\oplus             % bitwise exclusive or, ^
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect Some symbols have to be shifted around, to save computation time
%    we put them in boxes.
%    %
%    \begin{fixme}
%      The amount of the shifting depends on the used fonts. Particularly,
%      it depends on the usage of 10\,pt fonts. We use the plain \TeX{}
%      names for these fonts since we need {\it them\/} especially, it's not
%      possible to substitute them without changing these macros. If the
%      NFSS is used with \LaTeX{} the font names are not available, we have
%      to assert that they exist and that they are preloaded.
%    \end{fixme}
%    %
%    But there is one exception where we try to define a general look: the
%    increment operator~|++|. We might want to use it for different logos,
%    nowadays it's en vogue to attach |++| to all kinds of product names.
%    We choose to use the plus sign from script size (whatever this is
%    currently), but we must be careful that it is not used as a binary
%    operation. Instead we convert it to an ordinary symbol and set a
%    back-kern in between.
%
%    \begin{macros}{\teni,\sevensy,\xweb_pointer,\xweb_decr,\xweb_incr}
%    \begin{macrocode}
%<*main>
\font\teni=cmmi10
\font\sevensy=cmsy7

\newbox\xweb_pointer            % pointer to struct component, ->
\setbox\xweb_pointer=\hbox{\kern-2pt\lower3pt\hbox{\teni\char'176}\kern1pt}

\newbox\xweb_decr               % decrement, --
\setbox\xweb_decr=\hbox{%
            \kern .5pt
            \raise 1pt \hbox{\sevensy\char0 \kern-1pt\char0}%
            \kern .5pt
            }
\newbox\xweb_incr               % increment, ++
\setbox\xweb_incr=\hbox{%
            \kern .05em
            \raise .1em \hbox{$\scriptstyle {+}\kern -.1em{+}$}%
            \kern .05em
            }
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect Although the following symbols are typeset like an ``ordinary
%    \C++ programmer'' would expect them, we provide own module names
%    nevertheless. They can now be changed as well, i.e., orthogonality is
%    enhanced. (And we can use |\xweb_rebind| for assigning them to their
%    names while we switch to program state\,\dots).
%     %
%    \begin{fixme}
%      Must fix the comment on |\xwebMod|: Is C a ``modulo language''
%      or a ``remainder language.'' Well, IMHO $n
%      \mathbin{\hbox{\footnotesize\rm\%}} 
%      i$ with $n < 0$ shouldn't be used anyhow\,\dots
%    \end{fixme}
%
%    \begin{macros}{\xwebAddress,\xwebAssign,\xwebBinOr,\xwebComplement,
%       \xwebDecr,\xwebIncr,\xwebLeftShift,\xwebMod,\xwebMemberRef,
%       \xwebPointer,\xwebPointerMemberRef,\xwebRel,\xwebRightShift,
%       \xwebScope,\xwebThis}
%    \begin{macrocode}
%<*main>
\mathchardef\xwebAddress="2026  % `&', as binary op
\let\xwebAssign==               % assignment
\let\xwebBinOr=\mid             % binary or
\def\xwebComplement{{\sim}}     % `~', as ordinary symbol
\def\xwebDecr{\copy\xweb_decr}  % decrement
\def\xwebIncr{\copy\xweb_incr}  % increment
\let\xwebLeftShift=\ll          % left shift, <<
\def\xwebMod{\mathbin{\hbox{\footnotesize\rm\%}}}       % modulo/remainder, %
\def\xwebMemberRef{\mathbin{.*}}        % ptr to member (on object)
\def\xwebPointer{\copy\xweb_pointer}
\def\xwebPointerMemberRef{\mathbin{\xwebPointer*}} % ptr to member (on ptr)
\def\xwebRel{\mathrel?}         % relation operator
\let\xwebRightShift=\gg         % right shift, >>
\def\xwebScope{\kern.1em{::}\kern.1em}  % scope resolution

\def\xwebThis{\xwebRes{this}}   % reserved identifier `this'
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%    \sect Some tokens don't have constant names, the name is supplied as
%    the argument.
%    
%    Identifiers are typeset in italics, reserved words and type names in
%    boldface, and strings in typewriter.
%     %
%    \begin{fixme}  
%      The definition of the underscore in |\xwebRes| depends on a 10\,pt
%      type. Particularly, the height is 0.6\,pt and therefore 1.5~times as
%      high as the usual height (to get a bold impression). This height must
%      be adapted if another size is used. Is there a font dimension which
%      can be used as the default value for a rule?
%    \end{fixme}
%
%    \begin{macros}{\xwebCombinedOp,\xwebId,\xwebIdLetter,\xwebRes}
%    \begin{macrocode}
%<*main>
\def\xwebCombinedOp#1{\mathrel{\let\K==#1}}  % eg, += operator
\def\xwebId#1{\hbox{\it#1\/\kern.05em}} % identifier, more than one char
\def\xwebIdLetter#1{\hbox{$#1$}}        % identifier, one letter
\def\xwebRes#1{%                        % reserverd words and type names
    \hbox{\bf
        \def\_{\kern.04em\vbox{\hrule width.3em height .6pt}\kern.08em}%
        #1\/\kern .05em
        }%
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect In the plain version strings are typeset in the font |cmtex10|,
%    which is a typewriter font with extended ASCII characters. This font
%    does not have the usual accents and can therefore not used for
%    typesetting national characters. (Very often they are input in some
%    8-bit encoding, the respective character code is made active and is
%    substituted by a cseq which expands to the correct glyph. Of course,
%    there are better ways, but that's the reality we have to cope with.)
%    Instead of this special font we use the standard typewriter font.
%    This has the further advantage that |cmtex10| may not be introduced
%    to NFSS\@.
%    
%    \begin{sloppypar}
%     Within strings certain cseqs have a special meaning; this is
%     introduced by |\xweb_StringSetup|. The cseqs within strings are
%     mostly accessible by their ASCII code.
%    \end{sloppypar}
%    
%    \begin{sloppypar}
%     Every once in a while we have discretionary breaks in a string,
%     denoted by |\xwebStringBreak|. This break is shown with the C
%     convention of escaped newlines.
%    \end{sloppypar}
%
%    \begin{macros}{\xwebString,\xweb_StringSetup,\xwebStringBreak}
%    \begin{macrocode}
%<*main>
\def\xwebString#1{%
    \hbox{\tt
        \xweb_StringSetup
        #1\kern .05em
        }%
    }
\def\xweb_StringSetup{%
    \chardef\ =`\  %            % <-- two spaces !
    \chardef\&=`\&
    \chardef\\=`\\
    \chardef\^=`\^
    \chardef\_=`\_
    \chardef\{=`\{
    \chardef\}=`\}
    \chardef\~=`\~
    \def\`{`}%
    }
\def\xwebStringBreak{\discretionary{\hbox{\tt\char`\\}}{}{}}
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect Numbers are typeset in different ways. We use the definition of
%    the plain macros.
%     %
%    \begin{fixme}  
%      Should add a specification of the possible input and an explanation
%      of the macros below. In particular, that the closing brace after
%      |\aftergroup| is used much later is probably not grokked by most
%      \TeX{} programmers.
%  
%      Zden\v{e}k Wagner notes that with NFSS |\rm| in math mode is a noop.
%      Have to check a clean work-around.    
%    \end{fixme}
%
%    \begin{macros}{\xweb_oct,\xweb_hex,\xwebNumber}
%    \begin{macrocode}
%<*main>
\def\xweb_oct{\hbox{$^\circ$\kern-.1em\it\aftergroup\?\aftergroup}}
\def\xweb_hex{\hbox{$^{\scriptscriptstyle\#}$\tt\aftergroup}}

\def\xwebNumber#1{%             % octal, hex, or decimal constant
    \hbox{%
        $%
            \def\?{\kern.2em}%
            \def\$##1{\egroup\sb{\,\rm##1}\bgroup}% suffix to constant
            \def\_{\cdot 10^{\aftergroup}}% power of ten (via dirty trick)
            \let\~\xweb_oct \let\^\xweb_hex
            {#1}%
        $}%
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect Comments are typeset in \TeX{} state. We add a hook, the user
%    shall be able to change the layout (eg, he might want another font).
%     %
%    \begin{fixme}
%      Currently \C++ comments are typeset like C comments. This is horrible
%      in usual circumstances, i.e., when complete blocks of text are prefixed
%      with |//|. We should simply catenate all these text and typeset it as
%      one paragraph, each line prefixed by |//|. But then we have to
%      implement an |\everyline| first, and since that's not so easy we
%      postpone it\,\dots
%    \end{fixme}
%     %
%    In front of a C comment there is an optional stmt break, with 2\,quad
%    in front if the line is not broken and 1.5\,quad if the line is broken.
%
%    \begin{macros}{\xwebComment,\xwebCommentHook,\xwebCxxComment}
%    \begin{macrocode}
%<*main>
\def\xwebComment#1{%
    \5%                         % 0.5em will be discarded on line break
    \hskip 1.5em
    $/\ast\,$%
    {\xweb_tex
        \xwebCommentHook
        #1%
    }%
    $\,\ast/$%
    }
\let\xwebCommentHook\relax
\let\xwebCxxComment\xwebComment
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%  
%  
%    \chap \cweb{} tokens.
%    
%    We distinguish three categories of \cweb{} tokens: (1) Those which
%    output constant text, (2) those which have attributes to be displayed
%    in a special way, and (3) those which start a new structure element,
%    namely |@d| and~|@f|. Let's consider them in this order.
%    
%    
%    \sect \cweb{} tokens which expand in a constant string are the
%    identifier catenation operator~(`|@&|') and the macro placement
%    directive~(`|@h|').
%
%    \begin{macros}{\xwebIdCat,\xwebMacrosHere,\xwebRefMacrosHere}
%    \begin{macrocode}
%<*main>
\def\xwebIdCat{\xwebString{@\&}}
\def\xwebMacrosHere{%
    \begingroup
        \def\xwebRefNumber##1{}%
        \xwebRefName :\xwebRefMacrosHere\X
    \endgroup
    }
\def\xwebRefMacrosHere{Preprocessor Definitions}
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect Verbatim program strings, i.e., strings passed verbatim by
%    \ctangle{}~(`|@=|') are typeset like normal strings, but within a box.
%    We use 2\,pt as the separating distance, this is set locally.
%
%    \begin{macro}{\xwebVerbString}
%    \begin{macrocode}
%<*main>
\def\xwebVerbString#1{{\fboxsep\tw@\p@ \fbox{\xwebString{#1}}}}
%</main>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect The refinement names are typeset in angles, this has a long
%    tradition. We bury the typesetting of the section number (which is
%    the first parameter) in a macro call; the user may change this to
%    achieve special effects.
%     %
%    \begin{fixme}
%     One could think about handling special values of the section numbers
%     differently. Eg, an empty argument is not typeset at all, a~0 triggers
%     a marginal note about a missing definition, etc.
%    \end{fixme}
%    
%    \sect A refinement name may be typeset both in math and horizontal mode.
%    The name itself is typeset in horizontal mode, of course; for the
%    angles we need math mode. Therefore we assert at the start of the
%    macro that we're not in math mode any more. At the end we switch back
%    to math mode if we've started in it. This conditional switch from and
%    back to math mode is done by |\xweb_ToggleText|.
%    
%    \TeX{}nical note: If we're in math mode |\xweb_ToggleText| must be
%    defined globally, as it will turn off math mode and the definition
%    would be un-made then. The second invocation of |\xweb_ToggleText|
%    would be undefined then.
%    
%     \label{sec:refname-dot}
%     A refinement may also consist of the file name the expansion of this
%    refinement shall be written to. This file name is tagged with |\.|,
%    it shall be typeset like a string. But the user shall be able to use
%    the dot accent in the refinement name as well. We check if the text
%    consists solely of the tag and its argument; in this case we
%    substitute |\.| with |\xwebString|. Otherwise we leave it as it is.
%    Then a refinement name may not consist of a single dot-accented
%    expression---well, that's highly unlikely. (Nevertheless it's
%    documented in the user's manual)
%    
%    \begin{fixme}
%     I took the implementation strategy (i.e., the math mode toggle)
%     from the plain version. But
%     I don't understand why it was done this way. Why isn't it just an
%     hbox? Isn't that much simpler? Would it break something?
%    \end{fixme}
%
%    \begin{macros}{\xwebRefName}
%    \begin{macrocode}
%<*main>
\def\xwebRefName#1:#2\X{%
    \ifmmode  \gdef\xweb_ToggleText{\null$\null}%
    \else  \let\xweb_ToggleText\relax
    \fi
    \xweb_ToggleText
    $\langle\,${\xweb_tex \xweb_CheckDot{#2}\xwebRefNumber{#1}}$\,\rangle$%
    \xweb_ToggleText
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect  The |\xwebRefNumber| macro is used in the module names in
%    program text; It switches to footnotesize and calls
%    |\xwebSetModuleNumber| to create the reference text.
%
%    \begin{macro}{\xwebRefNumber}
%    \begin{macrocode}
%<*main>
\def\xwebRefNumber#1{%
    {\reset@font \footnotesize \kern .5em%
      \xwebSetModNrList#1.}}
%</main>
%    \end{macrocode}
%    \end{macro}  
%
%    
%    \sect There are two macros to typeset module numbers:
%    |\xwebSetModuleNumber| takes one number, and |\xwebSetModNrList|
%    takes a comma-separated list that is terminated by a period.
%    These macros must  employ |\thexwebModule| to get consistent 
%    numbers with nonstandard definitions of |\thexwebModule|. The
%    value of the |xwebModule| counter must be set with low-level
%    code; we cannot use |\setcounter| because it does a global set,
%    and we want to keep the change local, just for one-shot use.
%    (Else the number of the current module would be wrong after the
%    use of a module name.)
%
%    In hypertext, every section number becomes
%    a link to the corresponding section.
%    
%    \begin{macro}{\xwebSetModuleNumber}
%    \begin{macrocode}
%<*main>
\def\xwebSetModuleNumber#1{{\edef\tmpnr{#1}%
   \c@xwebModule=\tmpnr\relax
   \xweb_hlink{\thexwebModule}}}
%</main>
%    \end{macrocode}
%    \end{macro}  
%  
%
%    \sect  If we want to handle a comma-separated list of numbers, a
%    control sequence must be inserted before each element. The
%    following macros, essentially copied 
%    from \texttt{pdfcwebmac.tex} (plain cweb macros modified by
%    Andreas Scherer), insert |\xweb_TagSec| before each
%    number, filter things like |\ET|, and then expand the list.
%
%    \begin{macro}{\maketoks}
%    \begin{macrocode}
%<*main>
\newtoks\xweb_toksA
\newtoks\xweb_toksB
\newtoks\xweb_toksC
\newtoks\xweb_toksD
\newcount\xweb_countA
\xweb_countA=0
\def\xweb_AddTokens#1#2{%
    \edef\addtoks{\noexpand#1={\the#1#2}}\addtoks}
\def\xweb_adn#1{\xweb_AddTokens{\xweb_toksC}{#1}%
    \global\xweb_countA=1\let\next=\maketoks}
\def\xweb_poptoks#1#2|ENDTOKS|{%
     \let\first=#1\xweb_toksD={#1}\xweb_toksA={#2}}
\def\maketoks{%
    \expandafter\xweb_poptoks\the\xweb_toksA|ENDTOKS|
    \ifx\first0\xweb_adn0
    \else\ifx\first1\xweb_adn1 \else\ifx\first2\xweb_adn2
    \else\ifx\first3\xweb_adn3 \else\ifx\first4\xweb_adn4
    \else\ifx\first5\xweb_adn5 \else\ifx\first6\xweb_adn6
    \else\ifx\first7\xweb_adn7 \else\ifx\first8\xweb_adn8
    \else\ifx\first9\xweb_adn9
    \else
        \ifnum0=\xweb_countA\else\xweb_makenote\fi
        \ifx\first.\let\next=\xweb_tdone\else
            \let\next=\maketoks
            \xweb_AddTokens{\xweb_toksB}{\the\xweb_toksD}
            \ifx\first,\xweb_AddTokens{\xweb_toksB}{\space}\fi
        \fi
    \fi\fi\fi\fi\fi\fi\fi\fi\fi\fi
    \next
}
\def\xweb_makenote{\xweb_AddTokens{\xweb_toksB}%
    {\noexpand\xweb_TagSec{\the\xweb_toksC}}%
     \xweb_toksC={}\global\xweb_countA=0}
\def\xweb_tdone{\edef\st{\global\noexpand\xweb_toksA={\the\xweb_toksB}}\st}
%</main>
%    \end{macrocode}
%    \end{macro}
%    
%
%    \sect  By defining |\xweb_TagSec| to |\xwebSetModuleNumber| we
%    can now employ |\maketoks| in |\xwebSetModNrList| to typeset a
%    list of references.
%
%    \begin{macros}{\xweb_TagSec,\xwebSetModNrList}
%    \begin{macrocode}
%<*main>
\def\xweb_TagSec#1{\xwebSetModuleNumber{#1}}
\def\xwebSetModNrList#1.{%
   \setbox0=\hbox{\xweb_toksA={#1.}\xweb_toksB={}\maketoks}%
   \the\xweb_toksA}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect The next macro, |\xweb_CheckDot| is a hassle to implement. We
%    must check if it's argument consists solely of a `|\.|'~tag, together
%    with the argument to this tag. Then the `|\.|'-argument shall be
%    typeset like a string, |\.| itself must be ignored.
%  
%    The check for |\.| must not evaluate the parameter. Especially |\PB|
%    must not be evaluated within, it would lead to havoc with the
%    redefinition of all bindings, etc. (At least that's the empirical
%    result---it happened; although I don't know where the problems are.
%    Anyhow, it wasn't in the specs of the rebinding process.) All other
%    cseqs which shouldn't be used in moving arguments may cause problems
%    here, too. Note that |\protect| is no solution here, the user often is
%    not aware of the presence of \cweave{}-generated tags. As an example,
%    consider the refinement
%    {\tt |@< local variables of |\vbar|foo|\vbar|@>|\/} which will lead
%    to a call with the argument `|local variables of \PB{\\{foo}}|'.
%    |\\| must not be evaluated here. 
%    
%    I use an approach where I hope that it will work---but to be honest,
%    I'm not sure. I want to define a macro |\next| which shall have an
%    empty expansion iff |#1| was a `|\.|'~tag with its argument. Empty
%    refinement names are not allowed so we can assume that |#1| consists
%    of at least one token. I evaluate the first token of |#1| before the
%    |\def| is done. With an appropriate binding a |\.| will disappear,
%    perhaps leaving an empty token list. I also take care that |\PB| is
%    not evaluated then, by temporary rebinding it to |\relax|. Thereby I
%    have taken care for all cseqs \cweave{} might have introduced at the
%    very front of |#1|. Other cseqs are user-tags. If they cause
%    problems, the user might circumvent them by adding |\protect|.
%
%    \begin{macro}{\xweb_CheckDot}
%    \begin{macrocode}
%<*main>
\def\xweb_CheckDot#1{%
    \begingroup
      \let\.\@gobble
      \let\PB\relax
      \expandafter\def \expandafter\next \expandafter{#1}%
      \ifx \next\empty
         \gdef\next##1{\xwebString}%
      \else
         \global\let\next\relax
      \fi
    \endgroup
    \next #1
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect \cweb{} macro definitions (done by~|@d|) and format
%    directives are 
%    basically program text. When they are started we are already in
%    program state, i.e., |\B| has appeared in front of it. But since we have
%    an introductionary identifier (either |#define| or |format|) to set at
%    the very front we increase the indentation by three units.
%
%    \begin{macros}{\xwebDefine,\xwebFormat,\xweb_macro}
%    \begin{macrocode}
%<*main>
\def\xwebDefine{\xweb_macro{\#define}}
\def\xwebFormat\\#1\\#2\par{\ifxwebHideFormats\else
  \xweb_macro{format}\\{#1} \\{#2}\par\fi}
\def\xweb_macro#1{%
    \global\advance\xweb_indent \tw@\xwebIndentUnit
    \xweb_IncrIndent
    \xwebRes{#1 }%              % <-- blank!
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%  
%    \chap Section cross references and changes.
%    
%    At the end of sections with refinements, \cweave{} may output cross
%    reference information: In which sections additional definitions for
%    this refinement are found, where this refinement is used, and where it
%    is cited. This cross reference information is always introduced by a
%    tag followed by a non-empty list of section numbers. Different tags
%    are used for lists with only one element and for lists with more than
%    one element, this way the introductionary text may be adapted.
%    
%    Within a list of $n$~section numbers the first $n-1$~numbers are
%    separated by commas with one following blank. The last two numbers
%    are separated by |\ET| if~$n=2$, and by |\ETs| if~$n>2$. If a section
%    is changed by the changefile, a changeflag~(`|\*|') is appended to
%    its number. The list is eventually terminated by a full stop.
%  
%  
%    \sect We separate the cross reference information by a smallskip from
%    the refinement or from a previous cross reference information. The
%    information itself is typeset in a smaller font, as it is auxilliary,
%    inserted stuff. The number list has a hanging indentation of
%    |\xwebNumberListHangindent|. But beware: This isn't a dimension
%    register, it's a macro. This way one can use ems as dimensions.
%    
%    We must assert that we're in CR state while we set a cross reference.
%    
%    The first parameter of a cross reference information unit is the
%    introductionary text, the second is the number list. The parameters
%    must be evaluated in a group---local parameter changes therein must
%    not influence the environment. The list must be passed to
%    |\xwebSetModNrList| to typeset (and hyperreference) them correctly.
%
%    \begin{macros}{\xwebNumberListHangindent,\xwebCrossRef}
%    \begin{macrocode}
%<*main>
\def\xwebNumberListHangindent{2em}
\def\xwebCrossRef#1#2.{%
    \par\smallskip% (= \Y)
    \xweb_CR%
    \begingroup%
        \reset@font \footnotesize%
        \noindent \hangindent\xwebNumberListHangindent%
        #1~\xwebSetModNrList #2..\par%
    \endgroup%
    }%
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect Well, let's define all introducing tags, which in fact start the
%    cross reference information unit. The number list is gathered by
%    |\xwebCrossRef|.
%
%    \begin{macros}{\xwebCRAlso,\xwebCRCite,\xwebCRUse,
%                   \xwebCRsAlso,\xwebCRsCite,\xwebCRsUse}
%    \begin{macrocode}
%<*main>
\def\xwebCRAlso{\xwebCrossRef{See also section}}
\def\xwebCRsAlso{\xwebCrossRef{See also sections}}

\def\xwebCRCite{\xwebCrossRef{This code is cited in section}}
\def\xwebCRsCite{\xwebCrossRef{This code is cited in sections}}

\def\xwebCRUse{\xwebCrossRef{This code is used in section}}
\def\xwebCRsUse{\xwebCrossRef{This code is used in sections}}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect The changeflag is set as a star.
%
%    \begin{macros}{\xwebChangeFlag,\xwebCREt,\xwebCRsEt}
%    \begin{macrocode}
%<*main>
\let\xwebChangeFlag=*
\def\xwebCREt{ and~}
\def\xwebCRsEt{, and~}
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%  
%    \chap Including the web file.  Because the web document is
%    included  by the |\webfile| command, we have an easy way to
%    handle the index and list of refinements at the end; this is done
%    by the |\webfile| command itself.
%  
%    \sect As outlined above, we want to check if there are any entries in
%    the identifier index or the refinement list. The former is stored in
%    the file |\xwebJobname.idx|, the latter in the file |\xwebJobname.scn|.
%    For each of these files exists a flag named |xweb_|{\it
%    ext\/}|Entries| (where $\it ext \in \{ |idx|, |scn| \}$ is the
%    extension of the appropriate file) which tells if there are any
%    entries of the respective category.
%
%    \begin{macros}{\ifxweb_idxEntries,\ifxweb_scnEntries}
%    \begin{macrocode}
%<*main>
\newif\ifxweb_idxEntries
\newif\ifxweb_scnEntries
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect We consider a file as ``without entries'' if (1)~the file does
%    not exist, (2)~is empty, or (3)~has an empty line at the very front.
%    (In fact, case~(3) means that there should not be anything behind
%    it---but we can't test this portably.)
%    
%    |\xweb_HasEntries| tests the property, it's parametrized by the
%    extension. As a result, it sets the respective flag.
%    
%    We open the file first. Then we check if it doesn't exist or if it's
%    empty, both conditions deliver true on |\ifeof|; in this case we
%    pretend that there was an empty line. (The \LaTeX{} kernel
%    already provides 
%    a macro for an empty line, |\@defpar|.) Otherwise we read the first
%    line. At this state, the emptiness of the first line is equivalent to
%    the non-availability of entries, we can easily construct an
%    appropriate macro call to set the flag.
%
%    \begin{macros}{\xweb_TmpFile,\xweb_HasEntries}
%    \begin{macrocode}
%<*main>
\newread\xweb_TmpFile
\def\xweb_HasEntries#1{%
    \openin\xweb_TmpFile \xwebJobname.#1\relax
    \ifeof \xweb_TmpFile
        \let\next\@defpar
        \message{No #1 file present for \xwebJobname !}
    \else
        \read\xweb_TmpFile to \next
    \fi
    \csname xweb_#1Entries%
            \ifx \next\@defpar  false%
            \else  true%
            \fi
        \endcsname
    \closein\xweb_TmpFile
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%
%
%    
%    \sect Every web document can have its own table of contents.
%    It is stored in a file that has the web name as basename, and
%    extension \texttt{.con}.
%    The control sequence |\ZZ| is used to tag the entries.
%    |\xwebContents| typesets the table of contents.
%    |\xwebSetModuleNumber| is used here to typeset the section
%    number and possibly create a hyperlink.
%    
%    \begin{macros}{\ZZ,\xweb_contentsline,\xweb_cont,\xweb_consetup}
%    \begin{macrocode}
%<*main>
\newwrite\xweb_cont
\let\ZZ=\let % now you can \write the control sequence \ZZ
\def\xweb_contentsline#1#2#3#4{%
    \ifnum#2=0 \smallbreak\fi
    \hbox to \textwidth{\xweb_consetup{#2}#1
      \rm\leaders\hbox to .5em{.\hfil}\hfil\ %
      \xwebSetModuleNumber{#3}
      \hbox to3em{\hss#4}}}
\def\xweb_consetup#1{\ifcase#1 \bf % depth -1 (@**)
  \or % depth 0 (@*)
  \or \hskip2em % depth 1 (@*1)
  \or \hskip4em % depth 2 (@*2)
  \or \hskip6em % depth 3 (@*3)
  \or \hskip8em % depth 4 (@*4)
  \or \hskip10em % depth 5 (@*5)
  \else \hskip12em \fi} % depth 6 or more
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect  PDF\TeX\ will add an outline entry referring to the table
%    of contents.
%    
%    \begin{macros}{\xwebContents,\xwebSectionName,\xwebPageName}
%    \begin{macrocode}
%<*main>
\def\xwebContents#1{
    \def\readcontents{\IfFileExists{#1.con}{\input #1.con}{}}
    \begingroup
         \xwebContentsTop
         \ifnum\xweb_hypertype=2
            \pdfdest name{#1:contents} fith
            \pdfoutline goto name{#1:contents}{#1}
         \fi
         \hbox to \textwidth{\hfil
             \xwebSectionName\hbox to3em{\hss \xwebPageName}}
         \let\ZZ=\xweb_contentsline
         \readcontents\relax % read the contents info
         \xwebContentsBot    % print the contents page(s) and terminate
    \endgroup
}
\def\xwebSectionName{Section}
\def\xwebPageName{Page}
%</main>
%    \end{macrocode}
%    \end{macros}
%  
%  
%    \sect The |\xweb_InputWebfile| macro disables |\inx| etc., adds a
%    List Of Programs entry, inputs the web document and finishes it
%    with some code that was stolen from |\cweb@end_document| and
%    |\cweb@finish|. We don't need these macros themselves as there
%    should be no |\end{document}| in the web file.
%    
%    Note that there are two `jobnames': the |\jobname| of the main
%    document and the |\xwebJobname| of the included web document.
%
%    To get the jobname, we strip off the optional filename extension
%    with |\setname|, using its special parameter syntax. |##1| will
%    be the basename of the file; |##2| will be the extension, if
%    present. |##3| will only be set if the extension has mutltiple
%    parts; it also makes it possible to eat up the second dot, that
%    must be there to delimit the parameter text in case there is no
%    extension. We assume that there are no forward slashes in the
%    filename, so the forward slash can be used to delimit the third
%    parameter.
%
%    The flag |\xweb_FirstModule| is made true so we can find out
%    later if we are typesetting the first module (the table of
%    contents is set then).
%
%    \begin{macros}{\xwebContentsTop,\xwebContentsBot,\xweb_InputWebfile}
%    \begin{macrocode}
%<*main>
\def\xwebContentsTop{\vskip.2in}
\def\xwebContentsBot{\par\bigskip}
\def\xweb_InputWebfile#1{
    \def\setname##1.##2.##3/{\gdef\xwebJobname{##1}}
    \setname #1../
    \ifnum\c@xwebLopDepth > -10       % entry to the list of programs:
       \addcontentsline{lop}{program}{\xwebJobname}
    \fi
    \def\xwebContentsTop{\centerline{\textbf{\xwebJobname}}\vskip.2in}
    \def\xwebContentsBot{\par\bigskip}
    \global\xweb_FirstModuletrue
    \begingroup
       \let\inx\relax
       \let\fin\relax
       \let\con\relax
       \let\ch\xwebCRChanged
       \input{#1}
       \ifon \end{xwebModule} \fi % end the last module (if it is on).
    \endgroup
    % process the index and list of refinements ...
    \ifxwebIndex\xweb_HasEntries{idx}%
        \ifxweb_idxEntries  \xwebIdIndex{\xwebJobname.idx}\fi\fi
    \ifxwebRef\xweb_HasEntries{scn}%
        \ifxweb_scnEntries  \xwebRefList{\xwebJobname.scn}\fi\fi
    % clean up:
    \closeout\xweb_cont
    \onfalse % don't end the last section when starting the first section of
             % the next web.
    \xweb_UserBindings % back to the main document
}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect  |\xwebIdIndex| and |\xwebRefList| have a
%    filename argument, so that they can also be employed by the user
%    to create an index or refinement list for any web document in
%    any place, or to combine the indexes of several documents by
%    processing them with the |sort| program an including the result.
%    This can be particularly worthwile for authors of large,
%    multi-file software packages who want to have a global index of
%    their global variables, but they should almost certainly hack
%    the faked index file with a perl script or something alike to
%    mention also the filenames, because section numbers are not
%    unique through a set of web documents.
%
%    We add two special macros for this purpose, however, to take care
%    of things that are necessary to handle an index or reflist outside
%    the context of a web document.
%
%    \begin{macros}{\xwebInputIndex,\xwebInputReflist}
%    \begin{macrocode}
%<*main>
\def\xwebInputIndex#1{{
  \def\setname##1.##2\\{%
      \edef\xwebJobname{##1}
      \ifx\\##2\\%
    	 \edef\ext{idx}
      \else
    	 \edef\ext{\chop##2\\}%
      \fi}
  \def\chop##1.\\{##1}
  \expandafter\setname#1.\\
  \xwebIdIndex{\xwebJobname.\ext}
}}
\def\xwebInputReflist#1{{
  \def\setname##1.##2\\{%
      \edef\xwebJobname{##1}
      \ifx\\##2\\%
    	 \edef\ext{scn}
      \else
    	 \edef\ext{\chop##2\\}%
      \fi}
  \def\chop##1.\\{##1}
  \expandafter\setname#1.\\
  \xwebRefList{\xwebJobname.\ext}
}}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect The |\ifstr| macro compares its first and second
%    arguments; if 
%    they are equal it executes the third argument. It is necessary
%    that |\edef| is used here to expand the arguments!
%
%    \begin{macro}{\ifstr}
%    \begin{macrocode}
%<*main>
\def\ifstr#1#2#3{%
   \edef\xweb_tempa{#1}%
   \edef\xweb_tempb{#2}%
   \ifx\xweb_tempa\xweb_tempb #3\fi
   }
%</main>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect The |\webfile| macro has an optional argument, that may
%    contain 
%    a comma-separated list of options. |\webfile| expands into
%    |\xweb_file|, with the optional argument always present, but
%    possibly empty.
%
%    \begin{macro}{\webfile}
%    \begin{macrocode}
%<*main>
\def\webfile{\@ifnextchar[%
   {\xweb_file}{\xweb_file[]}}
%</main>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect The square-braced argument is mandatory for |\xweb_file|.
%    The comma-separated list of options is processed using a
%    |\@for| loop.
%    The macro will complain if an unknown option is
%    encountered.
%    After that, |\xweb_InputWebfile| is called to do the real work.
%    Default values for all options will be copied from their global
%    equivalents (specified with the |\usepackage| command).
%
%    \begin{macros}{\xweb_off,\xweb_on,\xweb_file,\cwebfile}    
%    \begin{macrocode}
%<*main>
\newif\if@opt
\def\xweb_off{\let\maybe=\iffalse}
\def\xweb_on{\let\maybe=\iftrue}
\def\xweb_file[#1]#2{
   \ifxweb_GlobalIndex\xwebIndextrue\else\xwebIndexfalse\fi
   \ifxweb_GlobalRef\xwebReftrue\else\xwebReffalse\fi
   \ifxweb_GlobalRagged\xwebRaggedtrue\else\xwebRaggedfalse\fi
   \ifxweb_GlobalOC\xweb_off\else\xweb_on\fi
   \ifxweb_GlobalCon\xwebContrue\else\xwebConfalse\fi
   \ifxweb_GlobalHideFormats\xwebHideFormatstrue\else
                            \xwebHideFormatsfalse\fi
   \xweb_hypertype=\xweb_GlobalHypertype
   \@for\xweb_opt:=#1\do{
     \typeout{webfiles option: \xweb_opt}
     \@optfalse
     \ifstr{\xweb_opt}{index}{\xwebIndextrue\@opttrue}
     \ifstr{\xweb_opt}{noindex}{\xwebIndexfalse\@opttrue}
     \ifstr{\xweb_opt}{reflist}{\xwebReftrue\@opttrue}
     \ifstr{\xweb_opt}{noreflist}{\xwebReffalse\@opttrue}
     \ifstr{\xweb_opt}{raggedbottom}{\xwebRaggedtrue\@opttrue}
     \ifstr{\xweb_opt}{flushbottom}{\xwebRaggedfalse\@opttrue}
     \ifstr{\xweb_opt}{onlychanges}{\xweb_off\@opttrue}
     \ifstr{\xweb_opt}{allsections}{\xweb_on\@opttrue}
     \ifstr{\xweb_opt}{nocon}{\xwebConfalse\@opttrue}
     \ifstr{\xweb_opt}{contents}{\xwebContrue\@opttrue}
     \ifstr{\xweb_opt}{hideformats}{\xwebHideFormatstrue\@opttrue}
     \ifstr{\xweb_opt}{showformats}{\xwebHideFormatsfalse\@opttrue}
     \ifstr{\xweb_opt}{hyperref}{\xweb_hypertype=1\@opttrue}
     \ifstr{\xweb_opt}{pdftex}{\xweb_hypertype=2\@opttrue}
     \ifstr{\xweb_opt}{nohype}{\xweb_hypertype=0\@opttrue}
     \if@opt\else\PackageError{webfiles}{%
          Unknown option for the \protect\webfile\space command
        }{Possible options are: index, noindex,
          reflist, noreflist, \MessageBreak
          raggedbottom, flushbottom, onlychanges,
          allsections,\MessageBreak
          nocon, contents, hideformats, showformats,
          hyperref, pdftex, nohype}
     \fi
   }
   \xweb_SetupHrefs
   \xweb_InputWebfile{#2}}
\let\cwebfile\webfile
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect The list of changed sections is a cross reference list, (nearly)
%    like all others at the end of a section. The only difference is that
%    we do not show changeflags any more---each section number in this list
%    carries a change flag by definition.
%    
%    \TeX{}nical note: The redefinition of |\*| is part of the second
%    argument of |\xwebCrossRef|. It is {\it not\/} a global redefinition.
%
%    \begin{macro}{\xwebCRChanged}
%    \begin{macrocode}
%<*main>
\def\xwebCRChanged{%
    \xwebCrossRef{The following sections were changed by the change file:}%
    \let\*\relax
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%  
%  
%    \sect The identifier index is available in the file
%    |\xwebJobname.idx|. 
%    The setup for the index is a mixture of the |theindex| environment
%    of the |article| style and DEK's index macros. It's typeset in two
%    columns; the user may specify an introductionary text for the index
%    by |\xwebIndexIntro|. If there is any introductionary text we add a
%    medium skip below.
%    
%    The paragraph layout is taken from the plain version: Each index
%    entry is a paragraph, nearly no skip between the paragraphs (just a
%    bit to prevent underfull vboxes), no paragraph indentation, ragged
%    right---but the |\parfillskip| set in such a way that almost empty
%    lines are avoided. Overfull hboxes in the index doesn't make
%    sense, so we prevent them. And we don't allow hyphenation in the
%    index, it's an identifier index after all.
%  
%    Before we read in this file, we have to bind the special cseqs used
%    therein.
%
%    \begin{macros}{\xwebIndexIntro,\xwebIndexName}
%    \begin{macrocode}
%<*main>
\newtoks\xwebIndexIntro
        \xwebIndexIntro={}
\def\xwebIndexName{Index of \texttt{\xwebJobname}}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect The following text is set as the header of the index. 
%
%    \begin{macro}{\xweb_IndexTop}
%    \begin{macrocode}
%<*main>
\def\xweb_IndexTop{
    \xweb_tex
    \par\vskip 1cm plus 10mm minus 5mm\noindent 
    {\bf \xwebIndexName}%\nopagebreak\par\medskip\nopagebreak
                        %% skip already inserted by xweb_twocolumn env.
    \edef\intro{\the\xwebIndexIntro}% % is a local def
    \ifx \intro\empty
    \else
       \noindent\the\xwebIndexIntro\unskip
       \par\medskip
    \fi
}
%</main>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect If the |multicol| package is available, it will be used
%    to typeset the identifier index. The |\RequirePackage| command
%    must however be placed after |\ProcessOptions|, at the end
%    of the package file.
%
%    If the twocolumn class option is in effect, multicols cannot be
%    used; in particular, the title (ieee.cls) would be set in one
%    column. It isn't necessary too, we are in two columns already.
%    
%    \begin{macro}{\ifxweb_multicol}
%    \begin{macrocode}
%<*main>
\newif\ifxweb_multicol \xweb_multicolfalse
\IfFileExists{multicol.sty}{
  \if@twocolumn\else\xweb_multicoltrue\fi
}{}
\ifxweb_multicol
  \newenvironment{xweb_twocolumn}{\begin{multicols}{2}}{\end{multicols}}
\else
  \newenvironment{xweb_twocolumn}{
      \if@twocolumn\else
        \columnseprule\z@
        \columnsep 35\p@          % value is from article.sty
      \fi
      \twocolumn%
  }{
      \onecolumn}
\fi
%</main>
%    \end{macrocode}
%    \end{macro}
%    
%    
%    \sect Now |\xwebIdIndex| itself.  PDF\TeX\ will add an outline
%    entry for the index.
%
%    \begin{fixme}
%      |vfil| before |\xweb_IndexTop| is still not strong enough!
%      A pagebreak can occur just after it.
%    \end{fixme}
%
%    \begin{macros}{\xwebJobName,\xweb_SetupIndex,\xweb_FinishIndex,
%        \xwebIdIndex}
%    \begin{macrocode}
%<*main>
\def\xwebJobName{noname}
\def\xweb_SetupIndex{%
    \begin{xweb_twocolumn}[\xweb_IndexTop]
    \ifnum\xweb_hypertype=2
       \pdfdest name{\xwebJobname:index} fith
       \pdfoutline goto name{\xwebJobname:index}{Index}
    \fi
    % go to CR mode
    \xweb_CR
    \message{*index: }% % tell the user what we're doing
    % paragraph layout
    \begingroup
    \parskip \z@ plus .5\p@
    \parindent\z@
    \rightskip \z@ plus 2.5em
    \parfillskip \z@ plus .6\hsize
    \tolerance\@M \hyphenpenalty\@M
    % bindings
    \let\I\xwebIndexEntry
    \let\[\xwebIndexDeclared
    \let\*\xwebLapStar
}
\def\xweb_FinishIndex{
    \endgroup
    \end{xweb_twocolumn}
}
\def\xwebIdIndex#1{%
    \xweb_SetupIndex
    \@input{#1}
    \xweb_FinishIndex
}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect An index entry is typeset with the same hanging indentation as`
%    a cross reference list.
%    
%    The entry is tagged with |\.|, if it was entered by the \cweb{}
%    operator~`|@.|'. Then it shall be typeset as a string. But an indexed
%    name may also want to use |\.| as an accent. This is the same
%    situation we had at the refinement names (see
%    section~\ref{sec:refname-dot}), where we introduced |\xweb_CheckDot|
%    to handle this case. The same minor restriction as there holds here,
%    a refinement name may not consist of a single dot-accented
%    expression. (|@:|~helps in this singular case.)
%
%    \begin{macro}{\xwebIndexEntry}
%    \begin{macrocode}
%<*main>
\def\xwebIndexEntry#1,#2.{%
    \par
    \hangindent\xwebNumberListHangindent
    \leavevmode
    \xweb_CheckDot{#1}:\quad\xwebSetModNrList #2.
    }
%</main>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect The sections where identifiers are declared are noted with
%    underlined numbers. We also must not forget the default declaration of
%    |\9|, the tag for the user definable index layout.
%
%    \begin{macros}{\xwebIndexDeclared,\9}
%    \begin{macrocode}
%<*main>
\def\xwebIndexDeclared#1]{\underline{#1}}
\def\9#1{}
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect The list of the refinement names is available in the file
%    |\xwebJobname.scn|. The layout is taken from the plain version: ragged
%    right, each entry is a paragraph, the different cross reference
%    categories are separated by a quad.
%  
%    We must restore |\parfillskip| and |\*| since it was changed in the
%    index.
%
%    \begin{macros}{\xwebJobname,\xwebReflistName,\xwebRLCite,
%                   \xwebRLsCite,\xwebRLUse,\xwebRLsUse}
%    \begin{macrocode}
%<*main>
\def\xwebReflistName{List of Refinements in \texttt{\xwebJobname}}
\def\xwebRLCite{\xwebCrossRef{Cited in section}}
\def\xwebRLsCite{\xwebCrossRef{Cited in sections}}
\def\xwebRLUse{\xwebCrossRef{Used in section}}
\def\xwebRLsUse{\xwebCrossRef{Used in sections}}
%</main>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \begin{macros}{\xwebRefList,\xweb_SetupReflist}
%    \begin{macrocode}
%<*main>
\def\xweb_SetupReflist{%
    \vskip 3ex plus 7ex minus 1ex
    \xweb_tex
    \noindent 
    {\bf \xwebReflistName}\nopagebreak\par\bigskip\nopagebreak
    \ifnum\xweb_hypertype=2
       \pdfdest name{\xwebJobname:reflist} fith
       \pdfoutline goto name{\xwebJobname:reflist} {Refs}
    \fi
    \xweb_CR 
    \message{*list of refinements: }%
    % paragraph layout: like in index, but
    \parfillskip\@flushglue
    \begingroup    % different bindings...
       \def\I{\par \hangindent\xwebNumberListHangindent}%
       \def\xwebCrossRef##1##2.{\quad {\reset@font\footnotesize
          ##1~\xwebSetModNrList ##2..}}%
       \def\Q {\xwebRLCite}%
       \def\Qs{\xwebRLsCite}%
       \def\U {\xwebRLUse}%
       \def\Us{\xwebRLsUse}%
       \let\*\xwebChangeFlag
}
\def\xwebRefList#1{%
       \xweb_SetupReflist
       \@input{#1}
    \endgroup
    }
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \noindent The redefinition of |\xwebCrossRef| etc.~must be done locally
%    to prevent troubles with trailing web files: Crossref info in these
%    files would be indented!
%
%
%    
%    \chap Bells and whistles.
%  
%    \begin{fixme}
%      Just copied from the plain version. It doesn't work
%      anyhow---|\char"|{\it xy\/} usually doesn't typeset the correct
%      character. That's because this character is most probably an active
%      character; at least that's typical for the way \TeX{} systems are
%      used in Europe. I have to think about the implementation.
%    \end{fixme}
%
%    \begin{macros}{\ATL,\postATL,\noATL,\noatl}
%    \begin{macrocode}
%<*main>
\def\ATL{\par\noindent\bgroup\catcode`\_=12 \postATL} % print @l in limbo
\def\postATL#1 #2 {\bf letter \\{\uppercase{\char"#1}}
   tangles as \tentex "#2"\egroup\par}
\def\noATL#1 #2 {}
\def\noatl{\let\ATL=\noATL} % suppress output from @l
%</main>
%    \end{macrocode}
%    \end{macros}
%    
%  
%    \sect Option processing will be done at the end of the package
%    file.  We must restore our catcode and are finished.
%
%    \begin{macrocode}
%<*main>
\ProcessOptions
\ifxweb_multicol
    \RequirePackage{multicol}
\fi
\catcode`\_=\xwebCatUsCode
%\endinput
%</main>
%    \end{macrocode}
%
%    
%    \chap Spidery Webs.
%
%    The file |swebbind.sty| redefines some macros to let the above
%    things work with web systems generated with Spider.
%    This file is input by |webkernel.tex|, as provided with the
%    webfiles distribution.
%    As it is eventually input by the |\webfile| command, it is
%    inside a group that encloses the entire web document, so the
%    scope of these redefinements is automatically limited to a single
%    web: we need no ``|cwebbind.sty|'' or such.
%
%    
%    \sect First, make the underscore usable in private control
%    sequences, as in |webfiles.sty|:
%    
%    \begin{macrocode}
%<*spider>
\catcode`\_=\xwebCatLetter
\catcode`\@=\xwebCatLetter
%</spider>
%    \end{macrocode}
%
%    
%    \sect Some miscellaneous\ldots
%
%    \begin{macros}{\amp,\SS,\PP}
%    \begin{macrocode}
%<*spider>
\let\amp\&    % ampersand
\let\SS\S     % section sign
\let\PP\P     % paragraph sign
%</spider>
%    \end{macrocode}
%    \end{macros}
%    
%
%    \sect The main section tag will be a mixture of |webfiles| and
%    |webkernel.tex|: 
%
%    |#1| = number
%
%    |#2| = (level and) title
%
%    \begin{macro}{\N}
%    \begin{macrocode}
%<*spider>
\def\N#1.#2.{%
   \ifon\end{xwebModule}\fi   % webfiles
   \global\xwebGroupLevel 0% default value for group level
   \xweb_headcheck#2\xweb_headcheck     % spider: get group level and title
   {\let\*=\empty%
      \xdef\xweb_secno{#1}% webfiles: get the section number
    }%
    \message \expandafter{*\xweb_secno}%
    \xweb_PrepareSection{#1}%
    \ifon\begin{xwebModule}{\bf\xweb_ModTitle.}%
               % \xweb_ModTitle is generated by \xweb_headcheck.
       %\hskip 1em plus.1em minus.1em%
       \xweb_SpiderLopEntry{\xwebGroupLevel}%
}
%</spider>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect  The entries in the list of programs and the web's own
%    table of 
%    contents are handled by |\xweb_SpiderLopEntry|. We have to use
%    |\@unexpandable@protect|; else there will be trouble with
%    insertion of |\xweb_ModTitle| in the contents file.
%
%    \begin{macro}{\xweb_SpiderLopEntry}
%    \begin{macrocode}
%<*spider>
\def\xweb_SpiderLopEntry#1{%
    \ifnum\c@xwebLopDepth > \xwebGroupLevel
       \addcontentsline{lop}{starred}{%
       \protect\global\xwebGroupLevel #1 \thexwebModule.~\xweb_ModTitle}%
       {   \let\protect\@unexpandable@protect
           \edef\next{\write\xweb_cont{%
             \ZZ{\xweb_ModTitle}{\the\xwebGroupLevel}%
                {\xweb_secno}{\noexpand\thepage}}}%
           \next 
       }% write "\ZZ{title}{depth}{sec}{page}" to .con file
    \fi
    \ifnum\c@xwebOutlineDepth > \xwebGroupLevel   
       \xwebPDFOutline{\xweb_secno}{\xweb_ModTitle}% args: nr, title
    \fi}
%</spider>
%    \end{macrocode}
%    \end{macro}
%    
%
%    \sect The following is from |webkernel|, with small additions for
%    |webfiles|. 
%    This stuff is to allow inital |=|, |1|, |2|, |3|, |4| in starred
%    modules. 
%    |=| means ``part'', don't skip page.
%    Normal starred module is |1|. 2--4 are submodules, and are
%    indented.
%
%    \begin{tabular}{ll}
%        |@*=|   &        bold name in table of contents\\
%                &        causes page eject\\
%                &        suppresses page eject following\\
%        |@*1,2| &        first level of indentation\\
%        |@*3,4| &        second level of indentation\\
%       |@*1,3| &       cause page eject\\
%       |@*2,4| &       don't cause page eject
%    \end{tabular}
%
%    \begin{macros}{\ifxweb_cancel,\xweb_ifnextchar,\xweb_ifnch,
%       \xweb_makethechar,\xweb_headcheck}
%    \begin{macrocode}
%<*spider>
\newif\ifxweb_cancel\xweb_canceltrue
\def\xweb_ifnextchar#1#2#3{\let\@tempe=#1\def\@tempa{#2}\def\@tempb{#3}%
   \xweb_ifnch}
\def\xweb_ifnch{%
    \ifx \@tempc \@tempe\let\@tempd\@tempa
    \else\let\@tempd\@tempb\fi
    \@tempd}
\def\xweb_makethechar#1{\let\@tempc=#1}

\def\xweb_headcheck#1#2\xweb_headcheck{%
    \xweb_makethechar{#1}%
    \def\theskipper{\vskip 3pt}%
                % extra skip before new starred module
    \def\xweb_ModTitle{{#2}}%
    \xweb_ifnextchar={%                                % @*= title.
        \global\xwebGroupLevel 0% webfiles
        \ifnum \xwebGroupLevel<\c@xwebSecNoEject
           \def\theskipper{\xwebMainSecSkip}%
        \fi
        \xweb_canceltrue
    }{\xweb_ifnextchar1{%                              % @*1 title.
        \global\xwebGroupLevel 1% webfiles
        \xweb_cancelfalse
        \ifnum \xwebGroupLevel<\c@xwebSecNoEject
           \def\theskipper{\xwebMainSecSkip}%
        \fi
    }{\xweb_ifnextchar2{%                              % @*2 title.
        \global\xwebGroupLevel 2% webfiles
        \xweb_cancelfalse
    }{\xweb_ifnextchar3{%                              % @*3 title.
        \global\xwebGroupLevel 3% webfiles
        \xweb_cancelfalse
        \ifnum \xwebGroupLevel<\c@xwebSecNoEject
           \def\theskipper{\xwebMainSecSkip}%
        \fi
    }{\xweb_ifnextchar4{%                              % @*4 title.
        \global\xwebGroupLevel 4% webfiles
        \xweb_cancelfalse
    }{% else                                           % @* title.
        \global\xwebGroupLevel 0% webfiles
        \ifxweb_cancel\else
           \ifnum \xwebGroupLevel<\c@xwebSecNoEject
              \def\theskipper{\xwebMainSecSkip}%
           \fi
        \fi
        \xweb_cancelfalse
        \def\xweb_ModTitle{#1{#2}}%
    }}}}}%
    \theskipper
}
%</spider>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect  Surround text in vertical bars: (already tagged with |\PB|
%    in Spider 3.0)
%
%    \begin{macro}{\CD}
%    \begin{macrocode}
%<*spider>
\def\CD#1\DC{#1}
%</spider>
%    \end{macrocode}
%    \end{macro}
%
%    
%    \sect Go into program mode:
%    this is |\P| in spider and |\B| in cweb.
%
%    \begin{macro}{\P}
%    \begin{macrocode}
%<*spider>
\def\P{\B}
%\let\P\B
%</spider>
%    \end{macrocode}
%    \end{macro}
%    
%
%    \sect Spidery WEAVE Bindings:
%    these are a little different from the CWEAVE bindings.
%
%    \begin{macros}{\xweb_CweaveBindings,\0,\1,\2,\3,\4,\5,\6,\7,\8,
%       \?,\AND,\CM,\DC,\S,\G,\GG,\I,\K,\LL,\MOD,\NULL,\R,\OR,\PA,
%       \this,\V,\W,\XOR,\L,\MG,\MGA,\MM,\PP,\.,\),\O,\MRL,
%       \C,\SHC,\X,\XF,\ATH,\D,\F,\J,\=,\*,\A,\As,\Q,\Qs,\U,\Us,
%       \ET,\ETs,\xweb_UserBindings}
%    \begin{macro}{\\}
%    \begingroup\catcode`\&=12 \catcode`\|=12
%      \begin{macro}{\&}
%      \begin{macro}{\|}
%    \endgroup
%    \begin{macrocode}
%<*spider>
\def\xweb_CweaveBindings{%
    \ifx \xweb_UserBindings\relax
    \xweb_rebind
        % indentation and paragraph layout
        \xweb_break            \0%           % SPIDER
        \xweb_IncrIndent       \1%
        \xweb_DecrIndent       \2%
        \xweb_ExprBreak        \3%
        \xweb_backup           \4%
        \xweb_OptBreak         \5%
        \xweb_break            \6%
        \xweb_BigBreak         \7%
        \xweb_noindent         \8%
        % C/C++ tokens	 
        \xwebRel               \?%
        \xwebAddress           \AND
        \xwebComplement        \CM
        \xwebScope             \DC
        \xwebEquiv             \S             % SPIDER
        \xwebGe                \G
        \xwebRightShift        \GG
        \xwebNe                \I
        \xwebAssign            \K
        \xwebLeftShift         \LL
        \xwebMod               \MOD
        \xwebNull              \NULL
        \xwebNot               \R
        \xwebBinOr             \OR
        \xwebMemberRef         \PA
        \xwebThis              \this
        \xwebOr                \V
        \xwebAnd               \W
        \xwebXor               \XOR
        \xwebLE                \L             % SPIDER
        \xwebPointer           \MG
        \xwebPointerMemberRef  \MGA
        \xwebDecr              \MM
        \xwebIncr              \PP
        % more tokens
        \xwebId                \\%
        \xwebIdLetter          \|%
        \xwebRes               \&%
        \xwebString            \.%        %% ( ...Emacs...
        \xwebStringBreak       \)%
        \xwebNumber            \O              % SPIDER
        \xwebCombinedOp        \MRL
        % goes to TeX state
        \xwebComment           \C
        \xwebCxxComment        \SHC
        \xwebRefName           \X
     \xwebSpiderOutputFileName \XF
        % CWEB tokens
        \xwebMacrosHere        \ATH
        \xwebDefine            \D
        \xwebFormat            \F
        \xwebIdCat             \J
        \xwebVerbString        \=           % SPIDER
        % cross reference tags
        \xwebChangeFlag        \*%
        \xwebCRAlso            \A
        \xwebCRsAlso           \As
        \xwebCRCite            \Q
        \xwebCRsCite           \Qs
        \xwebCRUse             \U
        \xwebCRsUse            \Us
        \xwebCREt              \ET
        \xwebCRsEt             \ETs
        % finish the list
        \stop\stop
    \def\xweb_UserBindings{%
        \xweb_RestoreBindings
        \let\xweb_UserBindings\relax
        }%
    \fi
    }
%</spider>
%    \end{macrocode}
%    \end{macro}
%    \end{macro}
%    \end{macro}
%    \end{macros}
%
%
%    \sect |\B| in spider is Begin controlled comment.
%    But there are no controlled comments in Spider, so
%    we can leave it out.
%
%    |\def\B{\mathopen{\.{@\commentbegin}}}|
%
%
%    \sect In spider, the argument of |\M| is ended by a period.
%    The meaning of the tag is the same.
%
%    \begin{macro}{\M}
%    \begin{macrocode}
%<*spider>
\def\M#1.{%
    \ifon\end{xwebModule}\fi
    \xweb_PrepareSection{#1}%
    \ifon\begin{xwebModule}
       \ifnum\c@xwebLopDepth>9
    	  \addcontentsline{lop}{xwebsection}{%
    	     \protect\global\xwebGroupLevel 4 \thexwebModule.}%
    	     \edef\next{\write\xweb_cont{\ZZ{}{4}{\xweb_secno}%
    		    {\thepage}}}\next % \ZZ{title}{depth}{sec}{page}%
    	     {   \let\protect\@unexpandable@protect
    		 \edef\next{\write\xweb_cont{%
    		   \ZZ{}{4}{\xweb_secno}{\thepage}}}%
    		 \next 
    	     }% write "\ZZ{title}{depth}{sec}{page}" to .con file
       \fi
    }
%</spider>
%    \end{macrocode}
%    \end{macro}
%    
%
%    \sect The index and the list of refinements are not given in |.inx|
%    and |.scn| files, 
%    but in the |.tex| file itself.
%    Furthermore, they are tagged a little differently:
%    \begin{quote}
%      \verb"\inx"\\
%      \meta{index}\\
%      \verb"\fin"\\
%      \meta{reflist}\\
%      \verb"\con"
%    \end{quote}
%
%    \begin{macros}{\inx,\fin,\con}
%    \begin{macrocode}
%<*spider>
\def\inx{
   \ifxwebIndex
      \xweb_SetupIndex
      \def\:{\I}
   \else
      \def\:##1.{}  % gobble \:\\{foo} 1, 2, 3.
   \fi
}
\def\fin{
   \ifxwebIndex
      \xweb_FinishIndex
   \fi
   \ifxwebRef
      \xweb_SetupReflist
      \def\:{\I}
   \else
      \def\:{}
      \def\XF##1\XF{}
      \def\X##1\X{}
      \def\U##1.{}
      \def\Us##1.{}
      \def\ET##1.{}
      \def\ETs##1.{}
   \fi
}
\def\con{
   \ifxwebRef
      \endgroup
   \fi
}
%</spider>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect Comments in Spider are not fixed; rather, the cseqs
%    |\commentbegin| and |\commentend| are set in |xweb.tex|.
%
%    \begin{macros}{\xwebComment,\xwebCommentHook,\xwebCxxComment}
%    \begin{macrocode}
%<*spider>
\def\xwebComment#1{%
    \5%                % 0.5em will be discarded on line break
    \hskip 1.5em
    \commentbegin%
    {\xweb_tex
    \xwebCommentHook
    #1%
    }%
    \commentend%
    }
\let\xwebCommentHook\relax
\let\xwebCxxComment\xwebComment
%</spider>
%    \end{macrocode}
%    \end{macros}
%    
%
%    \sect Macro definitions are not translated into preprocessor
%    directives; Spidery 
%    webs expand these themselves. Therefore they should not look like 
%    preprocessor directives: the `|#|' must be left out.
%
%    \begin{macros}{\xwebDefine,\xwebFormat}
%    \begin{macrocode}
%<*spider>
\def\xwebDefine{\xweb_macro{define}}
%\def\xwebFormat{\4\xweb_macro{format}}
\def\xwebFormat\\#1\\#2\par{\ifxwebHideFormats\else
  \4\xweb_macro{format}\\{#1} \\{#2}\par\fi}
%</spider>
%    \end{macrocode}
%    \end{macros}
%
%    
%    \sect The sequence |\XF#1:#2\XF| tags output files, instead of
%    |\X#1:\.{#2}\X|.
%    (|\XF| is bound to |\xwebSpiderOutputFileName| )
%
%    \begin{macro}{\xwebSpiderOutputFilename}
%    \begin{macrocode}
%<*spider>
\def\xwebSpiderOutputFileName#1:#2\XF{\xwebRefName{#1}:\.{#2}\X}
%</spider>
%    \end{macrocode}
%    \end{macro}
%    
%
%    \sect Restore catcodes:
%
%    \begin{macrocode}
%<*spider>
\catcode`\_=\xwebCatUsCode
\catcode`\@=\xwebCatOther
%</spider>
%    \end{macrocode}
%
% 
% \Finale
%
\endinput
%
%% \CharacterTable
%%  {Upper-case    \A\B\C\D\E\F\G\H\I\J\K\L\M\N\O\P\Q\R\S\T\U\V\W\X\Y\Z
%%   Lower-case    \a\b\c\d\e\f\g\h\i\j\k\l\m\n\o\p\q\r\s\t\u\v\w\x\y\z
%%   Digits        \0\1\2\3\4\5\6\7\8\9
%%   Exclamation   \!     Double quote  \"     Hash (number) \#
%%   Dollar        \$     Percent       \%     Ampersand     \&
%%   Acute accent  \'     Left paren    \(     Right paren   \)
%%   Asterisk      \*     Plus          \+     Comma         \,
%%   Minus         \-     Point         \.     Solidus       \/
%%   Colon         \:     Semicolon     \;     Less than     \<
%%   Equals        \=     Greater than  \>     Question mark \?
%%   Commercial at \@     Left bracket  \[     Backslash     \\
%%   Right bracket \]     Circumflex    \^     Underscore    \_
%%   Grave accent  \`     Left brace    \{     Vertical bar  \|
%%   Right brace   \}     Tilde         \~}