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author | Karl Berry <karl@freefriends.org> | 2007-10-24 23:29:14 +0000 |
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committer | Karl Berry <karl@freefriends.org> | 2007-10-24 23:29:14 +0000 |
commit | c5199a08bb8edc16006e6a5fc72cc704d7eae776 (patch) | |
tree | 729971967a99529b74598d27dd7cc585e0218e41 /Master/texmf-dist/doc/latex/cweb-latex/src/cwebbase.doc | |
parent | bfaf341636c39818969bd384bb1e5fda9195f3a5 (diff) |
new (to TL) cweb-latex package (4feb07)
git-svn-id: svn://tug.org/texlive/trunk@5271 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Master/texmf-dist/doc/latex/cweb-latex/src/cwebbase.doc')
-rw-r--r-- | Master/texmf-dist/doc/latex/cweb-latex/src/cwebbase.doc | 2059 |
1 files changed, 2059 insertions, 0 deletions
diff --git a/Master/texmf-dist/doc/latex/cweb-latex/src/cwebbase.doc b/Master/texmf-dist/doc/latex/cweb-latex/src/cwebbase.doc new file mode 100644 index 00000000000..280e53f82fc --- /dev/null +++ b/Master/texmf-dist/doc/latex/cweb-latex/src/cwebbase.doc @@ -0,0 +1,2059 @@ +% $StyleId: cwebbase.doc,v 1.4 1995/11/07 17:55:19 schrod Exp $ +%---------------------------------------------------------------------- +% Written by Joachim Schrod <schrod@iti.informatik.th-darmstadt.de>. +% Copyright conditions see below (GPL). + +% +% LaTeX macros cwebbase +% support for incorporation of CWEAVE markup in LaTeX documents +% +% [LaTeX in MAKEPROG] +% (history at end) + + + + +\documentclass{progltx} + +\usepackage{cweb-doc} % document-specific markup +\usepackage{fullpage} + + +\RCS $StyleRevision: 1.4 $ +\RCS $StyleDate: 1995/11/07 17:55:19 $ + + +\begin{document} + + +\title{Typesetting \cweave{} Output} +\author{% % LaTeX does not discard unnecessary glue... + Joachim Schrod% + \thanks{% + \protect\raggedright + TU~Darmstadt, Computer Science Department, WG Systems Programming, + Alexanderstr.~10, D-64283~Darmstadt, Germany. + Email: \texttt{schrod@iti.informatik.th-darmstadt.de}.% + }% + } +\date{% + Revision \RCSStyleRevision\\ + (as of \RCSStyleDate)% + } + +\maketitle + + +% doesn't work with progltx yet +%\tableofcontents + + + + +\chap Introduction. + +This code shall interpret and render the tag set output by \cweave{}. +That's realized in this module as it's needed in multiple places -- +when we want to use \LaTeX{} markup in \cweb{}, when we want to +incorporate \cweb{} pieces in \LaTeX{} documents (as examples, or in +textbooks), and when we want to incorporate whole \cweb{} documents in +a \LaTeX{} document. (That's by far the most difficult task.) + +As \cweb{} operates in modes, for obvious reasons our implementation +is based on a finite state automaton (FSA). The whole tag set is +separated into subsets that are valid in certain states. + +The complete set of tags does not obey any name conventions, some tags +are even in conflict with standard \LaTeX{} tags (e.g.\ |\\|). Most +tags are used to render code pieces. With the introduction of states +we can restrict the visibilities of these tags to those states where +we typeset program parts. The needed functionality will be available +in cseqs of our namespace, we'll map that to \cweave{}'s names in a +group. + +Then we have to implement the rendering of chunks and sections, that's +(more or less) a straight-forward task. Actually, we only set up the +basic code pieces, the integration of section divisions in the actual +\LaTeX{} document is a task of higher-level code; that integration +depends heavily on the type of document. That also implies that we +won't implement front or back matter material (document markup, table +of contents, index, list of refinements, etc.)\ in this module. + + +\sect Let's identify this module. + +\noindent The code below is explained in the implementation +documentation of the \pkg{rcs} package. + +\beginprog +\begingroup + \def\RCSFile#1#2 $#3: #4 #5\endRCS $#6: #7 #8\endRCS{% + \def\date{#4}\def\id{v#7}% + \ProvidesFile{#1}[\date\space\id\space #2]% + } + + \RCSFile{cwebbase.tex}{CWEAVE tags for LaTeX markup} + $StyleDate: 1995/11/07 17:55:19 $: 9999/00/00 \endRCS + $StyleRevision: 1.4 $: 0.0 \endRCS +\endgroup +\endprog + + +\sect This module is part of the supported \textsl{cweb-sty} bundle. +Send bug reports, comments and repairs. + +It assumes that the canonical setup of my modules has happened and can +be used herein. (In particular, the underscore is a letter.) + + +\sect This module reserves the namespace |cwbb|. It assumes that +|\cweb_warning| is bound either to |\PackageWarningNoLine| or +|\ClassWarningNoLine|, depending on the environment. + +\beginprog +\ifx \cwbb@loaded\undefined + \def\cwbb@loaded{$StyleRevision: 1.4 $} +\else + \cweb_warning{cwebbase}% + {Some other package already uses namespace `cwbb'} +\fi +\endprog + + +\sect This is freely distributable software; you can redistribute it +and/or modify it under the terms of the GNU General Public License as +published by the Free Software Foundation; either version~2 of the +License, or (at your option) any later version. + +This software is distributed in the hope that it will be useful, but +\textbf{without any warranty}; without even the implied warranty of +\textbf{merchantability} or \textbf{fitness for a particular purpose}. +See the GNU General Public License for more details. + +You should have received a copy of the GNU General Public License in +the file |License| along with this package; if not, write to the Free +Software Foundation, Inc., 675~Mass Ave, Cambridge, MA~02139,~USA. + + + + +% ------------------------------------------------------------ +% +% subdocument: The interface between CWEAVE and TeX +% + +\input{cweave-spec} + +% +% ------------------------------------------------------------ + + + + +\chap Interface of \pkg{cwebbase} module. + +\pkg{cwebbase} implements most of \cweave{} tags. It sets up tons of +redefinable cseqs, all of them start with |Cweb|. +% +\begin{fixme} + How do I document them? We need a configuration document anyhow. Do + I present here just a list of those cseqs realized in this module + and refer to the config docs? Need to wait until I have it, then + we'll see how the stuff here will be added. +\end{fixme} + + +\sect This module supports both hierarchic and flat section +structuring. You have to bind |\cweb@structure| to 0 (hierarchic) or 1 +(flat) before importing it, to show which structure is wanted. + + +\sect This module supports suppression of different document parts. +You have to define flags |@cweb@suppress@|\<foo>|@| with +$\mbox{\<foo>} \in \{ |changehints|, |unchanged|, |format| \}$ to +denote if suppression shall happen. + + +\sect The counter |secnumdepth| must be~11 if chunks shall be +numbered. That counter doesn't need to be set when this module is +imported, it can be set locally during typesetting \cweb{} code. + +The definitions for flat structure assume that |secnumdepth| is~11 +during typesetting. + + +\sect |\part|, |\chapter| (if available), and |\section| are used for +\cweb{} section divisions (those with the lowest ranks). These +commands will change the respective counters globally and will +add toc lines and marks. You might want to prevent that by redefining +|\addcontentsline| and |\mark|. + +Table of contents macros are not defined for the section divisions +introduced by this module. You must either prevent that they are +written to the |AUX| file at all; or you must define them. +% +\begin{fixme} + Add explanation of introduced section divisions. +\end{fixme} + +For flat structure, all section divisions are of type `|chunk|', like +chunks. The section names start with `|\cwbbRank{|\<rank>|}|'. By +default, |\cwbbRank| takes one argument and expands to the empty list +-- this can be redefined for the table of contents. + + +\sect The document end, as explained in the \cweave{} interface specs +(chunk~\ref{spec:sec:docend}), is not implemented. That must be done +by the user of this module -- if the back matter is to be processed at +all. + + + + +\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 chunk starts in the \textsl{documentation state}. + +\item |\B| switches to \textsl{program state}. This can happen in +documentation and program state. + +\item While we process the argument of |\PB| we're in \textsl{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 +\textsl{\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 cseq are bound to the meaning +described here. + +\item Cross reference information are attached to most chunks with +refinements. This information is processed in \textsl{CR state}. +After CR state material +comes always the next chunk 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} + +|\cwbb@documentation| will switch to documentation state, +|\cwbb@program| to program state, |\cwbb@Rprogram| to restricted +program state, |\cwbb@tex| to \TeX{} state, and |\cwbb@CR| to CR state. +If we're already in a state, the switch to this state shall be a +permissible null operation. + + +\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 \textsl{\cweave{} bindings}. In the +other two states the tags are largely defined by the user, the tag +set is called the \textsl{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 \textsl{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 \textsl{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{center} + \DeleteShortVerb\| +\begin{tabular}{r|c|c} +\multicolumn1{c|}{\textsc{State}} & \textsc{Binding} & \textsc{Layout} \\[1pt] +\hline +documentation & $U$ & $D$ \\ +program & $C$ & $P$ \\ +restricted program & $C$ & \\ +\TeX{} & $U$ & \\ +CR & $C$ & $D$ \\ +\end{tabular} + \MakeShortVerb\| +\end{center} + + +\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 |\cwbb@cweave_bindings| and +|\cwbb@program_layout|, we redefine |\cwbb@user_bindings| and +|\cwbb@doc_layout|. 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. + +\beginprog +\let\cwbb@user_bindings=\relax +\let\cwbb@doc_layout=\relax + +\def\cwbb@documentation{% + \cwbb@user_bindings + \cwbb@doc_layout + } +\def\cwbb@Rprogram{\cwbb@cweave_bindings} + +\def\cwbb@program{% + \cwbb@cweave_bindings + \cwbb@program_layout + } +\def\cwbb@tex{\cwbb@user_bindings} + +\def\cwbb@CR{% + \cwbb@cweave_bindings + \cwbb@doc_layout + } +\endprog + + + + +\chap Saving and restoring control sequences. + +We have a lot of cseqs which are defined within the namespace of this +module 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 get 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. (Why don't all those people who talk about +extending \TeX{} not just implement dynamic memory management for the +existing \TeX{}? It would still be \TeX{} and would \emph{really} be +a worthy activity. But not enough fun, I assume\,\dots) 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{\ttfamily foo}, is saved as the cseq with the +name \fbox{\ttfamily cweb\char `\\ foo}, i.e., as +|\csname cweb\string\foo \endcsname|. + + +\sect The save process is not done statically, but by the macro +|\cwbb@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, |\cwbb@to_restore| with the +cseqs which had a binding, and |\cwbb@undefined| with the names which +didn't have one. + +The saving is actually done by |\cwbb@save_binding|, |\cwbb@rebind| +is responsible for the initialization, |\cwbb@do_rebind| 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} + +\beginprog +\newtoks\cwbb@undefined +\newtoks\cwbb@to_restore + +\def\cwbb@rebind{% + \cwbb@undefined{}% + \cwbb@to_restore{}% + \cwbb@do_rebind + } +\def\cwbb@do_rebind#1#2{% + \ifx #1\stop + \let\next\relax + \else + \cwbb@save_binding #2% + \let #2=#1% + \let\next\cwbb@do_rebind + \fi + \next + } +\endprog + + +\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. + +\beginprog +\def\cwbb@save_binding#1{% + \ifx #1\undefined + \cwbb@undefined \expandafter{\the\cwbb@undefined #1}% + \else + \expandafter\let \csname cweb\string#1\endcsname =#1% + \cwbb@to_restore \expandafter{\the\cwbb@to_restore #1}% + \fi + } +\endprog + + +\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 |\cwbb@undefine| and |\cwbb@restore_binding| 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} + +\beginprog +\def\cwbb@restore_bindings{% + \expandafter\cwbb@undefine \the\cwbb@undefined \stop + \cwbb@undefined{}% + \expandafter\cwbb@restore_binding \the\cwbb@to_restore \stop + \cwbb@to_restore{}% + } + +\def\cwbb@undefine#1{% + \ifx #1\stop + \let\next\relax + \else + \let#1\undefined + \let\next\cwbb@undefine + \fi + \next + } +\endprog + + +\sect \TeX{}nical note: As in |\cwbb@save_binding|, the cseq-name for +the saved binding must be created before the |\let|s are executed. + +\begin{fixme} + Another |\next| assignment. +\end{fixme} + +\beginprog +\def\cwbb@restore_binding#1{% + \ifx #1\stop + \let\next\relax + \else + \expandafter\let \expandafter#1\csname cweb\string#1\endcsname + \expandafter\let \csname cweb\string#1\endcsname \undefined + \let\next\cwbb@restore_binding + \fi + \next + } +\endprog + + + + +\chap Chunks. + +All chunks are numbered subsequently. The chunk number is supplied as +part of the markup. In addition, the `changed' tag |\*| may be +appended to the chunk number. + +By default, chunks have approximately two picas vertical space in +front. + +If we use an hierarchic structure, we output the chunk number at the +refinement. (It's only needed to identify the refinement for cross +references.) But chunks are important structural units and thus should +be marked by typographic means that's more visible than the space +mentioned above, we add a `chunk start marker'. + +For a flat structure, we output the chunk number as the chunk start +marker, that is the traditional \WEB{} layout. + +In any case, the documentation part shall be run in after the chunk +start marker. + +\beginprog +\newskip\CwebChunkPreSkip + \CwebChunkPreSkip=2pc plus 1pc minus 6pt +\endprog + + +\sect In \LaTeX{}, structural divisions are best realized by +|\@startsection|, we'll use it also for chunk starts. The chunk start +marker is the section heading. For hierarchic structure, we use a +traditional paragraph sign, used since medieval times to tag new text +units. Our first test showed that the paragraph sign has typically an +underlength, that doesn't look good at the start of a chunk. We raise +the sign by its depth. + +For flat structure, we don't have text as the section heading, +but we have to cope for a deficiency of \LaTeX{}: It always leaves a +quad after the section number (by the way, this is not mentioned in +the documentation---you have to look in the macros to figure this +out). So we use a backskip of $\rm -1\,em$ as the chunk start marker +then. + +Changed chunks are marked by a changeflag, by default a star lapping +to the right. We need the information if that chunk is changed to +decide if we shall output the changeflag. We demand from the chunk +macros that they record that info in the flag |@cwbb_changed_chunk@|. + +Each structural division must be categorized, it belongs to a +\textsl{type}. This type determines also the name of the counter, the +mark handling for this category, and how this section tag is +represented in the table of contents. The type of chunks is `|chunk|' +(trivial, isn't it?). + +Furthermore, a structural division in \LaTeX{} has an associated +\textsl{level}. That level is used to determine if that division get +numbered in text or table of contents. For sections, we'll compute the +level from the rank, it will not be larger than the rank.% + \footnote{Check the next section for a more precise definition of + `rank' and `level'.} +Since the highest section rank is~10, we may use 11 as chunk level. + +For flat structure, we output the number for all section headings, +including chunks. For hierarchic structure we use the default maximum +level as supplied by our document class (e.g., 3~for \cls{article}, +and 2~for \cls{report} or \cls{book}). + +As a last point, we have to care already for sections in flat +structure. They will use the |chunk| category as well, we have to +distinguish them in the table of contents. For that, we'll record the +level in the text, it will get written to the table of contents. + +\beginprog +\newif\if@cwbb_changed_chunk@ +\let\CwebChangeFlag=* +\if@cweb@suppress@changehints@ + \let\cwbb@change_flag=\relax +\else + \let\cwbb@change_flag=\CwebChangeFlag +\fi +\def\cwbb@lap_change_flag{\rlap{\cwbb@change_flag}} + +\ifcase \cweb@structure + %% hierarchic + \let\CwebChunkHeadingStyle\relax + \newbox\cweb@chunk_marker + \setbox\cweb@chunk_marker=\hbox{\P} % tradition from medivial times + \setbox\cweb@chunk_marker=\hbox{% + \raise\dp\cweb@chunk_marker \box\cweb@chunk_marker + } + \def\CwebChunkHeadingMarker{\copy\cweb@chunk_marker} + \def\CwebChunkHeading#1{% + \CwebChunkHeadingMarker + \if@cwbb_changed_chunk@ \cwbb@lap_change_flag \fi + } + \or + %% flat + \def\cwbbRank#1{} + \def\CwebChunkHeadingStyle{\bfseries} + \def\CwebChunkHeading#1{% + \protect\cwbbRank{#1}% + \kern -1em + \if@cwbb_changed_chunk@ \cwbb@lap_change_flag \fi + } +\fi +\endprog + + +\sect Chunks are tagged with |\M| and get passed the chunk number as +argument. Before we evaluate |\@startsection|, we'll start the chunk. +That's common code to be used by sections as well, as they also +implicitely start a chunk. + +\beginprog +\def\M#1{% + \cwbb@start_chunk{#1}% + \@startsection + {chunk}% % category, == counter etc. + {11}% % level + {\z@}% % no indentation for heading + {\CwebChunkPreSkip}% % skip above heading + {\m@ne em}% % run-in heading, 1em distance to text + {\normalfont\CwebChunkHeadingStyle}% % layout + {\CwebChunkHeading{11}}% % text, level might go to toc file + } +\endprog + + +\sect But let's first declare how a chunk number is represented. The +principle rendering is controlled by |\thechunk|, namely, we get +arabic numbers. This rendering is used both for creation of the +section header (if in flat mode) and for cross references. I.e., +|\ref| expands into it. + +But for flat structure we need different expansions: In the section +header a period shall be appended, a cross reference shall appear +without such a period. We use two different macros: |\thechunk| +creates the number with the period, |\cwbb@refchunk| only the number. +The latter is used for a redefinition of |\@currentlabel|. Of course, +for hierarchic structure, both are the same. + +\beginprog +\newcounter{chunk} + +\def\cwbb@refchunk{\arabic{chunk}} + +\ifcase \cweb@structure + %% hierarchic + \let\thechunk=\cwbb@refchunk + \or + %% flat + \def\thechunk{\arabic{chunk}.} +\fi +\endprog + + +\sect Each chunk is started by |\cwbb@start_chunk|, which does the +common actions. First of all, we switch to documentation state. + +Then we store the chunk number in the |chunk| counter. That implies +that the chunk start must not step this counter! We'll take care for +that later by redefining |\refstepcounter|. The actual number is +passed as the argument, including an optional |\*| used to denote +changed chunks. We'll redefine that cseq to update the flag +|@cwbb_changed_chunk@|. + +Each chunk must be typeset with an open |\if| since it is finished by +|\fi|. If we shall suppress the output of unchanged chunks, we have +to use |\iffalse| if not |@cwbb_changed_chunk@|, otherwise |\iftrue|. +The flag |@cwbb_print_chunk@| is set up to provide an appropriate +test. + +When we typeset a chunk, we evaluate |\cwbb@init_print_chunk|. For +hierarchic structure, that cseq will be used to initialize the +typesetting of the chunk number at program parts. + +\beginprog +\if@cweb@suppress@unchanged@ + \def\if@cwbb_print_chunk@{\if@cwbb_changed_chunk@} + \@gobble\fi % close \if in case it's skipped +\else + \let\if@cwbb_print_chunk@=\iftrue + \@gobble\fi % same here +\fi + +\def\cwbb@start_chunk#1{% + \cwbb@documentation + \begingroup + \def\*{\global\@cwbb_changed_chunk@true}% + \global\@cwbb_changed_chunk@false + \global \c@chunk #1\relax % might expand \* + \endgroup + \if@cwbb_print_chunk@ + \cwbb@init_print_chunk + } +\endprog + + +\sect |\@startsection| will step the section counter (i.e., |chunk|). +Since we just assigned it in |\cwbb@start_chunk|, that would leave us +with a counter that's one too high. And our output in cross references +may be wrong, as a period is appended in flat structure. + +That damage all comes from one macro, |\refstepcounter|; let's +advice it to do the Right Thing for |chunk| counters. + +\beginprog +\let\cwbb@refstepcounter=\refstepcounter + +\def\cwbb@string@chunk{chunk} +\def\refstepcounter#1{% + \def\@tempa{#1}% + \ifx \@tempa\cwbb@string@chunk + \protected@edef\@currentlabel{\cwbb@refchunk}% + \else + \cwbb@refstepcounter{#1}% + \fi + } +\endprog + + + + +\chap Sections. + +Important sections are started on a new page, normal sections have the +same space as chunks in front. The very first section does not +automatically start on a new page since a title may be in front of it. + +Each section division has a \textsl{rank}, that denotes the section +depth as seen by \cweave{}. + +For this depth we compute a \textsl{level}, used to denote the section +depth for \LaTeX{}. This section depth is used to decide where +numbering shall stop, or if that entry shall be presented in the table +of contents, etc. + +These two numbers are not the same, due to the support of document +classes with chapters. + +We consider a section as important if it's rank is smaller than~3, +i.e., then we'll start a new page. This limit is controlled by the +number |\CwebRankNoEject|. The rank is used as the section level +and is therefore available to configure depth of typeset numbering and +appearance in table of contents. + +\beginprog +\def\CwebRankNoEject{3} +\endprog + + +\sect Sections are started with the macro |\N|. It's first parameter +is the section's rank. The second parameter is the chunk number, the +third the title of the section. This last parameter must be terminated +by a dot. + +Each section implicitly starts a chunk. As explained above, major +sections may eject the page, and we add our actual section heading +with |\CwebSection|. + +We also tell the user that we have reached the next section by telling +him about the current chunk number. 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. + +\beginprog +\def\N#1#2#3.{% + \cwbb@start_chunk{#2}% + \CwebEjectSection{#1}% + \CwebSection{#1}{#3}% + \begingroup + \def\*{}% + \edef\tmp{*#2}% + \message \expandafter{\tmp}% + \endgroup + } +\endprog + + +\sect At the start of a section we usually eject the page if our rank +is not too low. But if the user had a title above the first section, +he won't want this page break. So we try to guess it. If we guess +wrong, the user may either add |\newpage| himself or he may redefine +|\CwebEjectSection| in a package. + +\beginprog +\def\CwebEjectSection#1{% % #1 == rank + \gdef\CwebEjectSection##1{% + \relax + \ifnum ##1<\CwebRankNoEject\relax + \newpage + \fi + }% + } + +\if@titlepage + \CwebEjectSection{} +\fi +\endprog + + +\sect Now comes a heary piece. We have 11~section ranks, and need 11 +different section categories, section counters, etc. For flat +structure, they shall all do the same; for hierarchic structure, they +shall be really different. + +\noindent Let's have a look at the hierarchic structure first, it's +more complex. +% +\begin{itemize} + +\item We associate section rank~0 (that's `|@**|') with document + parts, i.e., map it to |\part|. Many smaller programs won't use it. + +\item If we are used in a class that has a bound cseq |\chapter|, we + associate rank~1 (`|@*0|') with it and rank~2 (`|@*1|') with + |\section|. Otherwise we associate rank~1 with |\section|. These + tags (|\chapter| and/or |\section|) must be defined because many + macros that want to create section divisions will use them. + +\item All other section ranks are placed below |\section|. + |\subsection| and other \LaTeX{} style markup is not supported. + + For hierarchic structure, we identify these sections with category + names `|section|$l$', where $l$ is the respective level, computed + from the rank. Those section names do not exist yet, we have to + create them. + +\end{itemize} + +Now we come to the point why we can't use the rank as the section +level passed to \LaTeX{}: When we assume the level usage of \LaTeX{}'s +standard classes, |\section| is \emph{always} on level~1, independent +of the existence of |\chapter|. The latter is placed on level~0, its +existence only influences the section level of |\part|, which is +either $-1$ or~0. + +This implies that |\subsection| in a standard class is always on +level~2, but our equivalent section division is either `|@*0|' +(rank~1) or `|@*1|' (rank~2). I.e., when we have chapters, we use a +level that's one lower than the rank, otherwise we use the rank. + +For flat structure, we use type |chunk|. This way we'll use the chunk +numbers, they are already set up. + +For flat structure, we will map all ranks to the same section markup. +This markup will also be accessible by |\section| or |\chapter|. They +will be declared to be on a level that is the same as the rank. + + +\sect The printed representation of a section divison number is simply +the presentation from the next upper level, a full stop, and an arabic +section number. When we compute the name of the previous level we must +pay attention to our first section division created this way. This +division must be placed below |section|, without any following number. + +Since registers are a valuable resource in \TeX{}, we have to take +care not to allocate a superfluous one. + +\beginprog +\ifcase \cweb@structure + %% hierarchic + \newcounter{section2}[section] + \@namedef{thesection2}{\@nameuse{thesection}.\arabic{section2}} + \newcounter{section3}[section2] + \@namedef{thesection3}{\@nameuse{thesection2}.\arabic{section3}} + \newcounter{section4}[section3] + \@namedef{thesection4}{\@nameuse{thesection3}.\arabic{section4}} + \newcounter{section5}[section4] + \@namedef{thesection5}{\@nameuse{thesection4}.\arabic{section5}} + \newcounter{section6}[section5] + \@namedef{thesection6}{\@nameuse{thesection5}.\arabic{section6}} + \newcounter{section7}[section6] + \@namedef{thesection7}{\@nameuse{thesection6}.\arabic{section7}} + \newcounter{section8}[section7] + \@namedef{thesection8}{\@nameuse{thesection7}.\arabic{section8}} + \newcounter{section9}[section8] + \@namedef{thesection9}{\@nameuse{thesection8}.\arabic{section9}} + \ifx \chapter\undefined + \newcounter{section10}[section9] + \@namedef{thesection10}{\@nameuse{thesection9}.\arabic{section10}} + \fi +\fi +\endprog + + +\sect Sections are typeset by |\CwebSection|; rank and title are the +arguments. + +For hierarchic structure, we select the proper cseq according to rank: +|\part|, |\chapter| if this is a structure with chapters, |\section|, +and |\cwbb@section{|\<rank>|}| for other ranks. For the last cseq we +also have to supply the section category, it's `|section|$l$' where +$l$ is the rank~$r$ if we don't have chapters, $r-1$ otherwise. + +That category cannot be computed by |\cwbb@section| itself since we +want to use that macro also for flat structure. But there all sections +are basically chunks, we have to use the |chunk| category there. Since +we want to differentiate them in the table of contents nevertheless, +we record the current rank in the title. + +\beginprog +\ifcase \cweb@structure + %% hierarchic + \ifx \chapter\undefined + \def\CwebSection#1#2{% + \ifcase #1 + %% 0 + \let\next\part + \or %% 1 + \let\next\section + \else %% level = rank + \def\cwbb@sect_name{section#1}% + \def\next{\cwbb@section{#1}}% + \fi + \next{#2}% + } + \else + \def\CwebSection#1#2{% + \ifcase #1 + %% 0 + \let\next\part + \or %% 1 + \let\next\chapter + \or %% 2 + \let\next\section + \else %% level = rank - 1 + \count@=#1 \advance \count@\m@ne + \edef\cwbb@sect_name{section\number\count@}% + \edef\next{\noexpand\cwbb@section{\number\count@}}% + \fi + \next{#2}% + } + \fi + \or + %% flat + \def\CwebSection#1#2{% + \def\cwbb@sect_name{chunk}% + \cwbb@section{#1}{\protect\cwbbRank{#1}#2}% + } + \def\section{% + \def\cwbb@sect_name{chunk}% + \cwbb@section{1}% + } +\fi +\endprog + + +\sect We use the same layout for all minor sections. That layout can +be changed by ammended by defining |\CwebSect|$r$|Hook| to redefine +|\CwebSectPreSkip| and/or |\CwebSectLayout| locally. (Of couse, it may +be redefined once globally, too.) These are the values to be used for +arguments 4 and~5 of |\@startsection|, pay attention to the skip sign, +telling about indentation of the first paragraph. And don't forget +that the skip is only used for sections on ranks below +|\CwebRankNoEject|, the others start on a new page anyhow. + +The default definition sets the section title in bold and leaves the +same space as before chunks. The first paragraph of the following +documentation has no indentation. + +Other layout changes (indentation for heading, etc.)\ must be made by +redefining |\cwbb@section|. Or---email me, if you want to do it. Then +I might be enclined to introduce further possibilities. + +\beginprog +\newskip\CwebSectPreSkip + \CwebSectPreSkip = -\CwebChunkPreSkip +\def\CwebSectLayout{\normalfont\bfseries} + +\def\cwbb@section#1{% % #2 (next token) is title + \csname CwebSect#1Hook\endcsname % \relax if undefined + \expandafter\@startsection + \expandafter{\cwbb@sect_name}% % category; for counter, etc. + {#1}% % level is rank + \z@ % no indentation for heading + \CwebSectPreSkip % skip above, maybe no next par indent + \medskipamount % skip below heading + \CwebSectLayout + } +\endprog + + + + +\chap Marks. + +\begin{fixme} + Since I don't know yet how to handle marks I ignore most of them for + the time being. + + Have to change this later. +\end{fixme} + +\beginprog +\let\chunkmark\@gobble + +\count@=2 +\@whilenum \count@<11 \do { + \expandafter\let \csname section\number\count@ mark\endcsname \@gobble + \advance \count@ by 1 + } +\endprog + + + + +\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 chunk will go to +another state. Since we have to do more for the material after |\B|, +we define this cseq later. + +\beginprog +\def\PB#1{% + \begingroup + \cwbb@Rprogram + \leavevmode + #1% + \endgroup + } +\endprog + + +\sect Note, that |\Y| cannot just be |\smallskip|, as in Plain +\cweb{}. 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 chunk break penalty---of course a chunk start is an even +better place for a page break\,\dots + +It might be that |\Y| is the very first token in a chunk. Then the +chunk start marker isn't set already since it is regarded as a run-in +section heading. In that case we don't set the vertical skip but +simply start the chunk 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. + +\beginprog +\newcount\CwebProgPenalty + \CwebProgPenalty=\@secpenalty + \divide\CwebProgPenalty by 2 +\def\Y{% + \if@noskipsec + \else + \par + \penalty\CwebProgPenalty + \smallskip + \fi + } +\endprog + + +\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 +|\cwbb@user_bindings| for this case, it will be redefined then. + +\beginprog +\def\cwbb@cweave_bindings{% + \ifx \cwbb@user_bindings\relax + \cwbb@rebind + % indentation and paragraph layout + \cwbb@incr_indent \1% + \cwbb@decr_indent \2% + \cwbb@expr_break \3% + \cwbb@backup \4% + \cwbb@opt_break \5% + \cwbb@break \6% + \cwbb@big_break \7% + \cwbb@noindent \8% + % C/C++ tokens + \CwebRel \?% + \CwebAddress \AND + \CwebComplement \CM + \CwebScope \DC + \CwebEquiv \E + \CwebGe \G + \CwebRightShift \GG + \CwebNe \I + \CwebAssign \K + \CwebLeftShift \LL + \CwebMod \MOD + \CwebNull \NULL + \CwebNot \R + \CwebBinOr \OR + \CwebMemberRef \PA + \CwebThis \this + \CwebOr \V + \CwebAnd \W + \CwebXor \XOR + \CwebLe \Z + \CwebPointer \MG + \CwebPointerMemberRef \MGA + \CwebDecr \MM + \CwebIncr \PP + % more tokens + \CwebId \\% + \CwebIdLetter \|% + \CwebRes \&% + \CwebString \.% %% ( ...Emacs... + \CwebStringBreak \)% + \CwebNumber \T + \CwebCombinedOp \MRL + % goes to TeX state + \CwebComment \C + \CwebCxxComment \SHC + \CwebRefName \X + % CWEB tokens + \CwebMacrosHere \ATH + \CwebDefine \D + \cwbb@format \F + \CwebIdCat \J + \CwebVerbString \vb + % cross reference tags + \cwbb@change_flag \*% + \CwebCRAlso \A + \CwebCRsAlso \As + \CwebCRCite \Q + \CwebCRsCite \Qs + \CwebCRUse \U + \CwebCRsUse \Us + \CwebCREt \ET + \CwebCRsEt \ETs + % finish the list + \stop\stop + \def\cwbb@user_bindings{% + \cwbb@restore_bindings + \let\cwbb@user_bindings\relax + }% + \fi + } +\endprog + + +\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 |\cwbb@save@parskip|. A few other layout +parameters from the document layout must be saved as well. + +\beginprog +\newskip\cwbb@save@parskip +\newskip\cwbb@save@rightskip +\newcount\cwbb@save@sem_sfcode +\newcount\cwbb@save@pretolerance +\newcount\cwbb@save@hyphenpenalty +\newcount\cwbb@save@exhyphenpenalty + +\def\cwbb@save_doc_layout{% + \cwbb@save@parskip\parskip + \cwbb@save@rightskip\rightskip + \cwbb@save@sem_sfcode\sfcode`\; + \cwbb@save@pretolerance\pretolerance + \cwbb@save@hyphenpenalty\hyphenpenalty + \cwbb@save@exhyphenpenalty\exhyphenpenalty + } +\def\cwbb@restore_doc_layout{% + \parskip\cwbb@save@parskip + \rightskip\cwbb@save@rightskip + \sfcode`\;=\cwbb@save@sem_sfcode + \pretolerance\cwbb@save@pretolerance + \hyphenpenalty\cwbb@save@hyphenpenalty + \exhyphenpenalty\cwbb@save@exhyphenpenalty + } +\endprog + + +\sect When |\cwbb@program_layout| 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 which might be changed by the user in the +preamble. This setup is done in |\cwbb@layout_init|. + +If the program layout is already active, we must not switch it on +another time. This can be tested by the current binding of +|\cwbb@doc_layout|. + +\beginprog +\def\cwbb@program_layout{% + \ifx \cwbb@doc_layout\relax + \cwbb@layout_init + \cwbb@save_doc_layout + \def\cwbb@doc_layout{% + \cwbb@restore_doc_layout + \let\cwbb@doc_layout\relax + }% + % set new values + \parskip\z@skip + \rightskip\z@ plus 100\p@ minus 10\p@ + \sfcode`\;=3000 + \pretolerance\@M + \hyphenpenalty 1000 % strings can be broken this way + \exhyphenpenalty\@M + \fi + } +\endprog + + +\sect The unit of the basic indentation is stored in +|\CwebIndentUnit|. Continuation lines are indented two units further, +i.e., the initial hanging indentation is 3~units. The current hanging +indentation is kept in |\cwbb@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 |\CwebIndentUnit|, it's done in the program state +initialization. + +\beginprog +\newdimen\CwebIndentUnit + \CwebIndentUnit=1em +\newdimen\cwbb@indent + +\newbox\cwbb@bak % backspace one unit +\newbox\cwbb@bakk % backspace two units + +\def\cwbb@layout_init{% + \global\setbox\cwbb@bak \hbox to -1\CwebIndentUnit{}% + \global\setbox\cwbb@bakk \hbox to -2\CwebIndentUnit{}% + \global\let\cwbb@layout_init\relax + } +\endprog + + +\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. Then we might add a marker +to this program part; for hierarchic structure we want to typeset the +chunk number in the margin of the chunk's program part. That's not +really possible, 'though: definitions and format requests are also +introduced with |\B|, so the chunk number will happen to be at the +start of the definition part if one exists. + +If the code line is the very first text to be typeset in this chunk, +we don't add the basic indentation---we're already indented from the +run-in chunk start marker. But we must not start our chunk with +|\noindent|, the marker would be typeset in the left margin then. (I +consider this as a \LaTeX{} error.) So we just emulate an empty +documentation part, the marker is now set correctly. |\B| can test for +this case: |@noskipsec| is still true then. + +\beginprog +\def\B{% + \cwbb@program + \cwbb@indent 3\CwebIndentUnit \hangindent\cwbb@indent + \ifvmode + \if@noskipsec + \indent % add an empty documentation part + \else + \noindent \kern\CwebIndentUnit + \fi + \fi + \CwebNumberProgramPart + } +\endprog + + +\sect The chunk number shall be added at the first program part. We +have a hook in the chunk start where we can set up +|\CwebNumberProgramPart|. It will redefine itself at first call, to +disable further output on more |\B| occurences in a chunk. + +The chunk number should always be in the left margin. If it's in the +right margin, there would be too much horizontal space between the +code start and the actual number. (The first code line is typically +not very long.) \LaTeX{} does not allow to select the margin for +marginpars, therefore we have to typeset the marginal note `by hand'. +As we know that we're in horizontal mode when we're called, |\vadjust| +is used to create the note. The standard \LaTeX{} dimen register for +the distance between marginal notes and text matter is used, of +course. + +Note that marginal notes may overwrite the chunk number. As it's very +unlikely that somebody issues marginal notes in program mode (that's +quite difficult and involves ingenious usage of the implementation of +this macros), I won't care for that case. + +\begin{fixme} + The baseline of the marginal note shall be aligned to the baseline + of the preceding line. That does not happen by default. Currently, I + assume that the preceding line has a depth of appropriately the + depth of a~`g'. Experiments showed that this gives good results for + most \cweb{} documents. But nevertheless one should determine the + exact depth of the preceding line, to know how much |box0| should be + raised. If anybody knows how this can be done, please tell me. (I + know about the route over the output routine, implementing an own + marginal note category, but this seems too much effort.) +\end{fixme} + +For flat structure, we don't add any program part marker and we +don't need to initialize it. + +\beginprog +\ifcase \cweb@structure + %% hierarchic + \def\cwbb@marginal_chunkno{% + \vadjust{% + \setbox\z@ \hbox to \z@{% + \hss \vphantom{g}% + \small \thechunk + \hskip \marginparsep + }% + \vbox to \z@{% + \hsize\z@ + \vss + \noindent \raise \dp\z@ \box\z@ + }% + }% + } + \def\cwbb@init_print_chunk{% + \def\CwebNumberProgramPart{% + \cwbb@marginal_chunkno + \let\CwebNumberProgramPart\relax + }% + } + \or + %% flat + \let\cwbb@init_print_chunk\relax + \let\CwebNumberProgramPart\relax +\fi +\endprog + + +\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. + +\beginprog +\def\cwbb@break{% % forced break, between statements + \ifmmode\else + \endgraf % in LaTeX it isn't sure what \par is really... + \noindent + \hangindent\cwbb@indent \kern\cwbb@indent + \copy\cwbb@bakk % go back to basic indentation + \ignorespaces + \fi + } +\def\cwbb@opt_break{% % optional break between statements + \hfil \penalty\m@ne + \hfilneg \kern .5em \kern 2\CwebIndentUnit % discarded on line break + \copy\cwbb@bakk + \ignorespaces + } +\def\cwbb@big_break{% % forced break and a little extra space + \Y + \cwbb@break + } +\def\cwbb@expr_break#1{% % break with penalty #1 * 10 + \hfil \penalty#10 + \hfilneg % discarded on line break + } +\endprog + + +\sect When we increment the indentation, we must not forget to set +the hanging indentation immediately since |\cwbb@opt_break| 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 + |\cwbb@decr_indent| as well? +\end{fixme} + +\beginprog +\def\cwbb@incr_indent{% + \global\advance\cwbb@indent\CwebIndentUnit + \hangindent\cwbb@indent + } +\def\cwbb@decr_indent{\global\advance\cwbb@indent -\CwebIndentUnit} +\def\cwbb@backup{\copy\cwbb@bak} +\def\cwbb@noindent{% % no indentation + \hskip -\cwbb@indent \hskip 2\CwebIndentUnit + } +\endprog + + + + +\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. + +\beginprog +\let\CwebAnd=\land % logical and, && +\let\CwebEquiv=\equiv % equiv sign, for == +\let\CwebGe=\ge % greater or equal +\let\CwebLe=\le % less or equal +\let\CwebNe=\ne % unequal, != +\let\CwebNull=\Lambda % NULL pointer +\let\CwebNot=\lnot % logical not, ! +\let\CwebOr=\lor % logical or, || +\let\CwebXor=\oplus % bitwise exclusive or, ^ +\endprog + + +\sect Some symbols have to be shifted around, to save computation time +we put them in boxes. + +\begin{fixme} + It's not sure if the following symbols still look good in other font + families than Computer Modern. The movements might need to get + adapted when more experience is available. They were chosen from + Plain \cweb{}, where these were explicit movements measured in + points. I changed the dimension to quads, to achieve at least the + support for different sizes in the Computer Modern family. +\end{fixme} + +\TeX{}nical note: The pointer symbol must not be declared as a math +symbol (e.g., with |\DeclareMathSymbol|). Then \TeX{} would insert an +italic correction behind it, according to rule~17 from appendix~G. +(Please send email if you know of an easy way to prevent that +addition.) So I use the symbol as an accent, but then I have to supply +a nucleus for this math list. That nucleus also determines the total +width of this construct. As the vector accent has a width of +approximately 5\,pt in |cmmi10|, I'm going to use 0.5\,em. (That +heuristic is as good as any other I can think of.) + +\beginprog +%% pointer to struct component (`->'), use symbol of \vec accent +\newbox\cwbb@pointer +\setbox\cwbb@pointer=\hbox{% + \kern -.2em + \lower .3em \hbox{$\vec{\kern .5em}$}% + \kern .1em + } + +\newbox\cwbb@decr % decrement, -- +\setbox\cwbb@decr=\hbox{% + \kern .05em + \raise .1em \hbox{$\scriptstyle {-}\kern -.1em{-}$}% + \kern .05em + } +\newbox\cwbb@incr % increment, ++ +\setbox\cwbb@incr=\hbox{% + \kern .05em + \raise .1em \hbox{$\scriptstyle {+}\kern -.1em{+}$}% + \kern .05em + } +\endprog + + +\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 |\cwbb@rebind| for assigning them to their +names while we switch to program state\,\dots). + +Note: The comment at |\CwebMod| says ``modulo/remainder'', as this is +not defined by the C standard, i.e., implementation-dependent. + +\beginprog +\mathchardef\CwebAddress="2026 % `&', as binary op +\let\CwebAssign== % assignment +\let\CwebBinOr=\mid % binary or +\def\CwebComplement{{\sim}} % `~', as ordinary symbol +\def\CwebDecr{\copy\cwbb@decr} % decrement +\def\CwebIncr{\copy\cwbb@incr} % increment +\let\CwebLeftShift=\ll % left shift, << +\def\CwebMod{\mathbin{\hbox{\footnotesize\rm\%}}} % modulo/remainder, % +\def\CwebMemberRef{\mathbin{.*}} % ptr to member (on object) +\def\CwebPointer{\copy\cwbb@pointer} +\def\CwebPointerMemberRef{\mathbin{\CwebPointer*}} % ptr to member (on ptr) +\def\CwebRel{\mathrel?} % relation operator +\let\CwebRightShift=\gg % right shift, >> +\def\CwebScope{\kern.1em{::}\kern.1em} % scope resolution + +\def\CwebThis{\CwebRes{this}} % reserved identifier `this' +\endprog + + +\sect The special identifier |\TeX| remains. In math mode it shall be +the identifier, in other modes the usual logo. We use the definition +supplied by DEK (or \textsc{Silvio Levy}?)\ from Plain \cweb{}. + +\beginprog +\def\TeX{% + {% + \ifmmode\it\fi + \mbox{T\kern-.1667em\lower.424ex\hbox{E}\hskip-.125emX}% + }} +\endprog + + +\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. For an underscore in the bold +words we use a line that's 50\,\% thicker as the usual line thickness. +-- But what is the usual line thickness. As Knuth uses 0.4\,pt for a +10\,pt Computer Modern font, we'll use 0.06\,em for a CM font in an +arbitrary size. If that line thickness is still OK for other fonts is +doubtful, as it should fit to the stem width. (CM is a rather light +font, after all.) But since there is no font dimension that gives a +hint to an appropriate line thickness, it's our best try. + +\beginprog +\def\CwebCombinedOp#1{\mathrel{\let\K==#1}} % e.g., += operator +\def\CwebId#1{\hbox{\it#1\/\kern.05em}} % identifier, more than one char +\def\CwebIdLetter#1{\hbox{$#1$}} % identifier, one letter +\def\CwebRes#1{% % reserverd words and type names + \hbox{\bf + \def\_{\kern.04em\vbox{\hrule width.3em height.06em}\kern.08em}% + #1\/\kern .05em + }% + } +\endprog + + +\sect In Plain \cweb{} 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\@. + +\beginprog +\def\CwebString{% + \hbox \bgroup + \tt + \cwbb@string_setup + \cwbb@string + } +\def\cwbb@string#1{% + #1\kern .05em + \egroup + } +\endprog + + +\sect Within strings certain cseqs have a special meaning; this is +introduced by |\cwbb@string_setup|. The cseqs within strings are +mostly special \TeX{} characters that are to be typeset by cseqs with +the same name. + +But a problem remains: active characters. They will still expand, and +will mess up the string visualization. This is a particular problem +with |german.sty| where the double quote is active. (Of course, that's +a problem -- I'm German. :--) When one typesets strings, a double +quote shall be typeset as double quotes, and must not expand to the +special meaning. Remember that double quotes happen to appear quite +often in strings. As the string argument is already tokenized, one has +to redefine the binding of $(\textit{\textup{symbol}}\ \textbf{.}\ +|#\"|)$. + +\begin{fixme} + Perhaps one might use a loop over all characters except the braces, + and set their catcode to other. That would give us enough security. + + For now, we handle only the double quote. +\end{fixme} + +Every once in a while we have discretionary breaks in a string, +denoted by |\CwebStringBreak|. This break is shown with the C +convention of escaped newlines. + +\beginprog +\def\cwbb@string_setup{% + \chardef\ =`\ % % <-- two spaces ! + \chardef\&=`\& + \chardef\\=`\\ + \chardef\^=`\^ + \chardef\_=`\_ + \chardef\{=`\{ + \chardef\}=`\} + \chardef\~=`\~ + \catcode`\"=\CatOther + } + +\def\CwebStringBreak{\discretionary{\hbox{\tt\char`\\}}{}{}} +\endprog + + +\sect Numbers are typeset in different ways. We use the definition of +Plain \cweb{}. +% +\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. +\end{fixme} + +\beginprog +\def\cwbb@oct{\hbox{$^\circ$\kern-.1em\it\aftergroup\?\aftergroup}} +\def\cwbb@hex{\hbox{$^{\scriptscriptstyle\#}$\tt\aftergroup}} + +\def\CwebNumber#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\~\cwbb@oct \let\^\cwbb@hex + {#1}% + $}% + } +\endprog + + +\sect Comments are typeset in \TeX{} state. We add a hook, the user +shall be able to change the layout (e.g., 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. + +\beginprog +\def\CwebComment#1{% + \5% % 0.5em will be discarded on line break + \hskip 1.5em + $/\ast\,$% + {\cwbb@tex + \CwebCommentHook + #1% + }% + $\,\ast/$% + } +\let\CwebCommentHook\relax +\let\CwebCxxComment\CwebComment +\endprog + + + + + +\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|'). + +\beginprog +\def\CwebIdCat{\CwebString{@\&}} +\def\CwebMacrosHere{% + \begingroup + \def\CwebRefNumber##1{}% + \CwebRefName :Preprocessor definitions\X + \endgroup + } +\endprog + + +\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. + +\beginprog +\def\CwebVerbString#1{{\fboxsep\tw@\p@ \fbox{\CwebString{#1}}}} +\endprog + + +\sect The refinement names are typeset in angles, this has a long +tradition. We burry the typesetting of the chunk 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 chunk numbers + differently. E.g., an empty argument is not typeset at all, a~0 + triggers a marginal note about a missing definition, etc. +\end{fixme} + +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 |\cwbb@toggle_text|. + +\TeX{}nical note: If we're in math mode |\cwbb@toggle_text| must be +defined globally, as it will turn off math mode and the definition +would be un-made then. The second invocation of |\cwbb@toggle_text| +would be undefined then. + +A refinement may also consist of the file name the expansion of this +refinement shall be written to. +% +\label{sec:refname-dot} +% +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 |\CwebString|. +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 I'll document it in the user's manual\,\dots) + +\begin{fixme} + One should be able to use |\EnsureMath| here. But the refinement + name must not be set in math mode and must not be set in an hbox; + the latter would prevent line breaks. +\end{fixme} + +\beginprog +\def\CwebRefName#1:#2\X{% + \ifmmode \gdef\cwbb@toggle_text{\null$\null}% + \else \let\cwbb@toggle_text\relax + \fi + \cwbb@toggle_text + $\langle\,${\cwbb@tex \cwbb@check_dot{#2}\CwebRefNumber{#1}}$\,\rangle$% + \cwbb@toggle_text + } +\def\CwebRefNumber#1{% + {\reset@font \footnotesize \kern .5em#1}% + } +\endprog + + +\sect The next macro, |\cwbb@check_dot| 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 \verb"@< local variables of |foo| @>|" 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 circumstance them by adding |\protect|. + +\beginprog +\def\cwbb@check_dot#1{% + \begingroup + \let\.\@gobble + \let\PB\relax + \expandafter\def \expandafter\next \expandafter{#1}% + \ifx \next\empty + \gdef\next##1{\CwebString}% + \else + \global\let\next\relax + \fi + \endgroup + \next #1% + } +\endprog + + +\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. + +The output of format directives may be suppressed. Then we have to +gather both identifiers that will appear after |\F|. Both of them +consist of one group-token (a cseq and the identifier name), after +each identifier one other token separates them. I.e., we have to +gobble six group-tokens. As the very last token is |\par| if a format +directive follows directly on another one, the definition must be +long. + +\TeX{}nical note: |\cwbb@format| must expand to |\CwebFormat|, not to +its expansion. Otherwise a redefinition of |\CwebFormat| in a package +would not be used. + +\beginprog +\def\CwebDefine{\cwbb@macro{\#define}} +\def\CwebFormat{\cwbb@macro{format}} +\if@cweb@suppress@format@ + \long\def\cwbb@format#1#2#3#4#5#6{} +\else + \def\cwbb@format{\CwebFormat} +\fi + +\def\cwbb@macro#1{% + \global\advance\cwbb@indent \tw@\CwebIndentUnit + \cwbb@incr_indent + \CwebRes{#1 }% % <-- blank! + } +\endprog + + + + +\chap Refinement cross references and changes. + +At the end of chunks with refinements, \cweave{} may output cross +reference information: In which chunks 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 chunk 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 $n$~chunk 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 chunk +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 +|\CwebNumberListHangindent|. But beware: This isn't a dimension +register, it's a macro. This way one can use ems as dimensions. + +The actual size change is represented by a macro. We will redefine it +when we need an other size, e.g., in the lists at the end of the +document. + +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. + +\beginprog +\def\CwebNumberListHangindent{2em} +\let\CwebCRSize\footnotesize +\def\CwebCrossRef#1#2.{% + \par\smallskip + \cwbb@CR + \begingroup + \reset@font \CwebCRSize + \noindent \hangindent\CwebNumberListHangindent\relax + #1~#2.\par + \endgroup + } +\endprog + + +\sect Well, let's define all introducing tags, which in fact start the +cross reference information unit. The number list is gathered by +|\CwebCrossRef|. + +\beginprog +\def\CwebCRAlso{\CwebCrossRef{See also chunk}} +\def\CwebCRsAlso{\CwebCrossRef{See also chunks}} + +\def\CwebCRCite{\CwebCrossRef{This code is cited in chunk}} +\def\CwebCRsCite{\CwebCrossRef{This code is cited in chunks}} + +\def\CwebCRUse{\CwebCrossRef{This code is used in chunk}} +\def\CwebCRsUse{\CwebCrossRef{This code is used in chunks}} + +\def\CwebCREt{ and~} +\def\CwebCRsEt{, and~} +\endprog + + + + +\chap Bells and whistles. + +\begin{fixme} + Just copied from Plain \cweb{}. It doesn't work + anyhow---|\char"|\<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} + +\beginprog +\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 +\endprog + + + +\chap The end. + +Well, after all we're finished with this module + +\beginprog +\endinput +\endprog + + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% + +\vskip \PltxPreSectSkip + +\rcsLogIntro{After the actual revision log of this module, we give an + extract of log messages of the \cls{cweb} class. This module was + extracted from revision~2.8 of that class, we present to you the + log entries that concern the code of the new module.} + +\begin{rcslog} +$StyleLog: cwebbase.doc,v $ +\Revision 1.4 1995/11/07 17:55:19 schrod + \LaTeX{} \cweb{} should work at least with the last two \LaTeX{} +versions; make it work with the previous-to-last one, version +\mbox{$\langle$1994/12/01$\rangle$}. For that, one has to install the +\mbox{$\langle$1995/06/01$\rangle$} (non-outer) definition of +|\newif|, and |\hb@xt@| must not be used.\\ +Problem reported by Laurent Desnogues +\path|<laurent.desnogues@aiguemarine.unice.fr>| and somebody else (XXX +-- add name). + +\Revision 1.3 1995/11/07 14:13:12 schrod +Reset section numbers when higher-level section begins.\\ +Error reported by Bronne Louis \path|<bronne@montefiore.ulg.ac.be>|. + +\Revision 1.2 1995/11/06 10:58:47 schrod + Support active double quotes in strings. That happens when +|german.sty| is used. Problems with other active characters may still +appear. + +\Revision 1.1 1995/09/12 23:02:22 schrod +Moved all code that does the actual typesetting of \cweave{} tags and +is therefore also needed for a |cweb| environment. It's now an own +module named \pkg{cwebbase}. + +Chunk markers and chunk marginal numbers don't hang below the +baseline any more. + + +\item[] \noindent\hrulefill\break + \textbf{Extract of the revision log for |cweb.doc|:} + + \vskip 2ex + +\Revision 2.5 1995/08/29 02:07:26 schrod +Discard dependencies on 10\,pt fonts. + +Support suppression of format directives. + +\Revision 2.4 1995/08/27 19:31:43 schrod +Make configuration of change flag easier. + +Put section title of changed chunks list in marks, and tell the user +that it got typeset. + +\Revision 2.3 1995/08/27 17:24:46 schrod +Make usage of baseclass with chapters work. + +\Revision 2.2 1995/08/27 13:26:22 schrod +Add possibility to suppress change hints. + +\Revision 2.1 1995/08/25 19:11:18 schrod +Hierarchic structures are supported now, in addition to the flat +structure of the beta-test version. One can choose with an option. For +that step, the terminology was cleaned up, too: Chunks are not named +sections any more. (That change involved reimplementation of almost +all the structure and toc stuff.) + +The chunk number supplied by \cweave{} is used now, not some computed +number. Change flags are printed, too. + +One can suppress output of unchanged sections. + +\Revision 1.12 1993/08/10 14:15:43 schrod +New page on main section only if group level $<$ |\cwebSecNoEject|. +Default for the latter is 3. + +\Revision 1.11 1993/08/10 11:21:07 schrod +Reference to section number does not render a period after the +number any more. + +\Revision 1.10 1993/08/09 20:08:20 schrod +|\cweb@cweave_bindings| is now a no-op if \cweave{} bindings are in +effect already.\\ +(Problem reported by Michael M\"uller \path|<mimu@mpi-sb.mpg.de>|.) + +\Revision 1.9 1993/08/09 18:05:28 schrod +Left shift operator wasn't defined correctly.\\ +(Problem reported by Michael M\"uller \path|<mimu@mpi-sb.mpg.de>|.) + +\Revision 1.6 1993/06/15 08:49:23 schrod +|\cweb@check_dot| must not evaluate its argument in an |\edef|, this +causes problems if a |\PB| is within. Now I try hard not to evaluate any +tokens outside of my control. + +Can use |\@defpar| for an empty line in |\cweb@has_entries|, don't +need an own macro. + +\Revision 1.4 1993/06/14 15:54:18 schrod +Add FSA diagram about processing states. CR state is also switched +to from \TeX{} state (that happens with |\ch| at the document end). + +\Revision 1.3 1993/05/13 17:51:21 schrod +Refinements may also be filenames (`|@(|'). Then the complete name +consists of a |\.| macro call, which is handled now.\\ +(Problem reported by Michael M\"uller \path|<mimu@mpi-sb.mpg.de>|.) + +Made the detection of `|@.|' index entries more robust. + +\Revision 1.2 1993/05/12 18:28:59 schrod +Adapted to recent changes of \cweave{} (of April 93): + +Main sections have a group level, represented in the table of +contents. This changed the complete implementation of section tags. + +New C token cseqs: |\Z| and |\MRL|, implemented as |\CwebLe| and +|\CwebCombinedOp|. + +\Revision 1.1 1993/04/09 15:00:37 schrod +Initial revision + +\end{rcslog} + + + +\end{document} + + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +Local Variables: +mode: LaTeX +TeX-brace-indent-level: 4 +indent-tabs-mode: t +TeX-auto-untabify: nil +TeX-auto-regexp-list: LaTeX-auto-regexp-list +compile-command: "make cwebbase.tex" +End: |