float.sty

%%% ====================================================================
%%% @LaTeX-style-file{
%%%     filename        = "float.sty",
%%%     version         = "1.1c",
%%%     date            = "18 December 1992",
%%%     time            = "10:00:00 CET",
%%%     author          = "Anselm Lingnau",
%%%     address         = "Hochschulrechenzentrum/FB Mathematik
%%%                        Johann Wolfgang Goethe-Universit\"at
%%%                        Postfach 11 19 32
%%%                        DW-6000 Frankfurt am Main
%%%                        Germany",
%%%     telephone       = "+49 798 2554",
%%%     checksum        = "56253 815 4764 35676"
%%%     email           = "lingnau@math.uni-frankfurt.de (Internet)",
%%%     codetable       = "ISO/ASCII",
%%%     keywords        = "LaTeX, figure, table, floats",
%%%     supported       = "yes",
%%%     docstring       = "
%%%
%%%     float.sty
%%%
%%%     A LaTeX style option which defines a \newfloat command
%%%     to define new classes of floats in the spirit of \newtheorem.
%%%     Floats can be defined to use any of various 'float styles'.
%%%     float.sty also incorporates the functionality of David Carlisle's
%%%     here.sty, giving floats a [H] option, meaning 'do not float',
%%%     or 'PUT IT HERE'.
%%%
%%%     Documentation requires Frank Mittelbach's doc.sty.",
%%% }
%%% ========================================================================
%
% Beware of file version and date in banner at top of implementation below.
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% * Version 1.1a, added here.sty functionality.
% * Version 1.1b, \@Esphack in place of \@esphack. Removed spurious
% *     whitespace. Fixed documentation. Thanks to David Carlisle.
% * Version 1.1c, \@Esphack hack for compatibility with old LaTeXes. Fixed
% *     checksums. Removed spurious blank line at end of file. Thanks again.
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%<*x>
% This file may be used without modification as a style (.sty) file.
%
% If you have Mittelbach's doc.sty, this file may be formatted with a
% command like:
%               latex float.sty
%
% If you have the Mittelbach/Duchier/Braams docstrip utility, you may
% produce a faster loading .sty file. Rename this file to: float.doc
% Then run this file through *plain* TeX:
%               tex float.doc
% This should produce the file float.sty.
% If you do not have plain TeX on your system, you can trick LaTeX into
% doing the work as follows:
%               latex \def\fmtname{plain} \input float.doc
% Note that you may need to quote the arguments here to stop your
% operating system treating the \ characters incorrectly.
%
%               latex float.doc
% will produce a typeset version of the documentation, as above.
%
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\def\plain{plain}\ifx\fmtname\plain\csname fi\endcsname
  \def\batchfile{float.doc}
  \input docstrip
  \preamble
  Do not distribute the stripped version of this file.

  \endpreamble
  \generateFile{float.sty}{t}{\from{float.doc}{}}
  \endinput
\fi
%
\ifcat a\noexpand @\let\next\relax\else\def\next{%
  \documentstyle[float,doc]{article}\MakePercentIgnore}\fi\next
%
%\def\eatmodule<#1>{}\eatmodule
%</x>
% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% \textwidth=355pt      ^^A Allow macrocode text with 72 columns
% \CodelineIndex        ^^A Code lines numbered
% \EnableCrossrefs      ^^A No Cross References
% \MakeShortVerb{\|}    ^^A |\foo| works like \verb+|\foo|
% \CheckSum{467}
%
% \DoNotIndex{\@Esphack,\@Mii,\@Miv,\@cons,\@currlist,\@dblarg,\@dbldeferlist}
% \DoNotIndex{\@dblfloat,\@dottedtocline,\@eha,\@esphack,\@float}
% \DoNotIndex{\@floatpenalty,\@ifnextchar,\@ifundefined,\@latexerr}
% \DoNotIndex{\@mkboth,\@namedef,\@nameuse,\@parboxrestore,\@spaces}
% \DoNotIndex{\@starttoc,\@tempa,\@tempboxa,\@tempdima,\@warning}
% \DoNotIndex{\addcontentsline,\advance,\arabic,\bf,\bgroup,\box,\chapter}
% \DoNotIndex{\columnwidth,\csname,\def,\dimen,\docdate,\edef,\egroup,\else}
% \DoNotIndex{\endcsname,\endinput,\expandafter,\fi,\filedate,\fileversion}
% \DoNotIndex{\global,\hbadness,\hbox,\hfil,\hrule,\hsize,\ht,\if@twocolumn}
% \DoNotIndex{\ifdim,\iffalse,\ifnum,\iftrue,\ifvbox,\ifx,\ignorespaces}
% \DoNotIndex{\intextsep,\kern,\let,\long,\moveleft,\newbox,\newcount}
% \DoNotIndex{\newcounter,\newif,\noexpand,\normalsize,\numberline,\par}
% \DoNotIndex{\parindent,\penalty,\prevdepth,\protect,\refstepcounter,\relax}
% \DoNotIndex{\rm,\section,\setbox,\space,\textheight,\the,\typeout,\unvbox}
% \DoNotIndex{\uppercase,\vadjust,\vbox,\vrule,\vskip,\wd,\wlog,\z@}
%
% \title{An Improved Environment for Floats}
% \author{Anselm Lingnau\thanks{Hochschulrechenzentrum/Fachbereich Mathematik,
%    Johann Wolfgang Goethe-Universit\"at, Postfach 11\,19\,32,
%    DW-6000 Frankfurt am Main.
%    E-Mail: {\tt lingnau@math.uni-frankfurt.de}}%
%    \thanks{Part of this style option is based on
%    {\tt here.sty} by David Carlisle ({\tt carlisle@cs.man.ac.uk}),
%    who also provided helpful criticism.}}
% \date{8 October 1992}
% \floatstyle{ruled}
% \newfloat{Program}{tbp}{lop}[section]
% \floatstyle{plain}
% \newfloat{Example}{t}{lox}[section]
% \floatstyle{boxed}
% \restylefloat{table}
% \begin{document}
% \maketitle
%
% \begin{abstract}
%   This style option improves the interface for defining floating
%   objects such as figures and tables in \LaTeX{}.
%   It adds the notion of a `float style' that governs appearance
%   of floats.
%   New kinds of floats may be defined using a |\newfloat| command
%   analogous to |\newtheorem|.
%   This style option also incorporates the functionality
%   of David Carlisle's {\tt here.sty},
%   giving floating environments a {\tt [H]} option which means `PUT IT HERE'
%   (as opposed to the standard {\tt [h]} option which means
%   `You may put it here if you like').
% \end{abstract}
%
% \section{Introduction}
%
% Among the features of \LaTeX\ are `floating' figures and tables
% that drift from where they appear in the input text to, say, the top
% of a page. The contents and formatting of floats is pretty much up
% to the user, except that there is a |\caption| command that
% governs formatting of the caption --- it is centered if it is short,
% and formatted as a paragraph if it is longer than a single line of text.
% Sometimes other types of floating objects, e.g., algorithms or programs,
% are desirable, but they must be defined by analogy to the existing
% floats since there is no simple command for doing this. This goes
% beyond the knowledge or inclination of the average \LaTeX\ user.
%
% In this style option, I present an interface to floating objects
% that attempts to fix some of these shortcomings.
% First of all, I introduce the notion of a `float style'.
% A float style governs the appearance of a class of floats like a page style
% governs the appearance of a page (\LaTeX\ has page styles {\tt plain},
% {\tt empty} and {\tt headings}, among others). This style option
% provides some exemplary float styles:
% \begin{description}
% \item[plain] This is the float style that \LaTeX\ normally applies to
%   its floats, i.e., nothing in particular. The only difference is
%   that the caption comes out {\em below\/} the body of the float,
%   regardless of where it is given in the text.
% \item[boxed] The body of the float is printed inside a box. The caption
%   goes below that box.
% \item[ruled] This float style is patterned on the table style of
%   {\sl Concrete Mathematics}. The caption is printed at the top of the
%   float, surrounded by rules; another rule finishes off the float.
% \end{description}
%
% \begin{Program}
% \begin{verbatim}
% #include <stdio.h>
%
% int main(int argc, char **argv)
% {
%        int i;
%        for (i = 0; i < argc; ++i)
%                printf("argv[%d] = %s\n", i, argv[i]);
%        return 0;
% }
% \end{verbatim}
% \caption{The first program. This hasn't got anything to do with the style
%    but is included as an example. Note the {\tt ruled} float style.%
%    \label{prog1.1}}
% \end{Program}
% To facilitate the definition of new floating objects, {\tt float.sty}
% supports the |\newfloat| command. This command is comparable to
% |\newtheorem| in that it allows the user to add a new class of floats
% at the document level. No style option hacking is necessary.
% There's also a |\listof| command that prints a listing of all the
% floats of a given type, like |\listoffigures| and |\listoftables|
% in vanilla \LaTeX.
%
% \section{The User Interface --- New Floats}
%
% \DescribeMacro{\newfloat}
% The most important command in {\tt float.sty} is the |\newfloat|
% command. As mentioned above, it is patterned on |\newtheorem|.
% The |\newfloat| command takes three required and one optional
% argument; it is of the form\\[2pt]
% \hspace*{\MacroIndent}|\newfloat{|\meta{type}|}{|^^A
%   \meta{placement}|}{|\meta{ext}|}[|\meta{within}{\tt]}\\[2pt]
% \meta{type} is the `type' of the new class of floats, like {\tt program}
% or {\tt algorithm}. After the appropriate |\newfloat|, commands
% like |\begin{program}| or |\end{algorithm*}| will be available.
% \meta{placement} gives the default placement parameters for this class
% of floats. The placement parameters are the same as in standard \LaTeX,
% i.e., {\tt t}, {\tt b}, {\tt p} and {\tt h} for `top', `bottom',
% `page' and `here', respectively.
% When \LaTeX\ writes the captions to an auxiliary file for the list
% of figures (or whatever), it'll use the job name followed by \meta{ext}
% as a file name.
% Finally, the optional argument \meta{within} determines whether floats
% of this class will be numbered within some sectional unit of the document.
% For example, if \meta{within}$=${\tt chapter}, the floats will be numbered
% within chapters. (In standard \LaTeX, this happens with figures and tables
% in the {\tt report} and {\tt book} document styles.)
% As an example, Program~\ref{prog1.1} above was created by a command
% sequence similar to that shown in the following Example.
% \begin{Example}[H]
% \begin{verse}
% |\floatstyle{ruled}|\\
% |\newfloat{Program}{tbp}{lop}[section]|\\
% \dots\ loads o' stuff \dots\\
% |\begin{Program}|\\
% |\begin{verbatim}|\\
% \dots\ program text \dots\\
% |\end{verbatim}|\\
% |\caption{|\dots\ caption \dots|}|\\
% |\end{Program}|
% \end{verse}
% \caption{This is another silly floating Example. Except that this one
%   doesn't actually float because it uses the {\tt[H]} optional parameter
%   to appear {\bf Here}. (Gotcha.)}
% \end{Example}
%
% \DescribeMacro{\floatstyle}
% The |\floatstyle| command sets a default float style. This float style
% will be used for all the floats that are subsequently defined using
% |\newfloat|, until another |\floatstyle| command appears.
% The |\floatstyle| command takes one argument, the name of a float
% style. For instance, |\floatstyle{ruled}|. Specifying a string that
% does not name a valid float style is an error.
%
% \DescribeMacro{\floatname}
% The |\floatname| command lets you define the {\em float name\/} that
% \LaTeX\ uses in the caption of a float, i.e., `Figure' for a figure
% and so on. For example, |\floatname{program}{Program}|.
% The |\newfloat| command sets the float name to its argument
% \meta{type} if no other name has been specified before.
%
% \DescribeMacro{\floatplacement}
% The |\floatplacement| command resets the default placement specifier
% of a class of floats. E.g., |\floatplacement{figure}{tp}|.
%
% \DescribeMacro{\restylefloat}
% The |\restylefloat| command is necessary to change styles for the
% standard float types {\tt figure} and {\tt table}. Since these aren't
% usually defined via |\newfloat|, they don't have a style associated
% with them. Thus you have to say, for example,\\[2pt]
% \hspace*{\MacroIndent}|\floatstyle{ruled}|\\
% \hspace*{\MacroIndent}|\restylefloat{table}|\\[2pt]
% to have tables come out {\tt ruled}. The command also lets you change
% style for floats that you define via |\newfloat|, although this
% is, typographically speaking, not a good idea.
% See table~\ref{table1} for an example.
% \DeleteShortVerb{\|}
% \begin{table} \def\B#1{$\displaystyle{n\choose#1}$}
% \begin{center} \begin{tabular}{c|ccccc}
% $n$&\B0&\B1&\B2&\B3&\B4\\ \hline
%  0 & 1\\
%  1 & 1&1\\
%  2 & 1&2&1\\
%  3 & 1&3&3&1\\
%  4 & 1&4&6&4&1
% \end{tabular} \end{center}
% \caption{Pascal's triangle. This is a re-styled \LaTeX\ {\tt table}.%
%   \label{table1}}
% \end{table}
% \MakeShortVerb{\|}
%
% \DescribeMacro{\listof}
% The |\listof| command produces a list of all the floats of a given
% class. Its syntax is\\[2pt]
% \hspace*{\MacroIndent}|\listof{|\meta{type}|}{|\meta{title}^^A
%   |}|\\[2pt]
% \meta{type} is the float type given in the |\newfloat| command.
% \meta{title} is used for the title of the list as well as the headings
% if the current page style includes them. Otherwise, the |\listof|
% command is analogous to the built-in \LaTeX\ commands
% |\listoffigures| and |\listoftables|.
%
% \section{The User Interface --- {\tt[H]} Placement Specifier}
%
% Many people find \LaTeX's float placement specifiers too restrictive.
% A Commonly Uttered Complaint (CUC) calls for a way to place a float
% exactly at the spot where it occurs in the input file, i.e., to {\em not\/}
% have it float at all.
% It seems that the {\tt[h]} specifier should do that, but in fact it
% only suggests to \LaTeX\ something along the lines of ``put the float
% here if it's OK with you''. As it turns out, \LaTeX\ hardly ever feels
% inclined to actually do that. This situation can be improved by
% judicious manipulation of float style parameters.
%
% The same effect can be achieved by changing the actual method of
% placing floats. David Carlisle's {\tt here.sty} introduces a new float
% placement specifier, namely {\tt[H]}, which, when added to a float,
% tells \LaTeX\ to ``put it HERE, period''. If there isn't enough space
% left on the page, the float is carried over to the next page together
% with whatever follows, even though there might still be room left for
% some of that.
% This style option provides the {\tt[H]} specifier for newly defined
% classes of floats as well as the predefined {\tt figure}s and
% {\tt table}s, thereby superseding {\tt here.sty}. David suggests
% that the {\tt here.sty} be withdrawn from the archives in due course.
%
% The {\tt[H]} specifier may simply be added to the float as an optional
% argument, like all the other specifiers.
% It may {\em not\/} be used in conjunction with any other placement
% specifiers, so {\tt[Hhtbp]} is illegal.
% Neither may it be used as the default placement specifier for a whole
% class of floats.
% The following table is
% defined like this:
% \begin{verse}
% |\begin{table}[H]|\\
% |\begin{tabular}{cl}|\\
% |\tt t & Top of the page\\|\\
% \dots\ more stuff \dots\\
% \end{verse}
% (It seems that I have to add some extraneous chatter here just so that
% the float actually comes out right in the middle of a printed page.
% When I \LaTeX ed the documentation just now it turned out that there
% was a page break that fell exactly between the ``So now'' line and the
% float. This wouldn't Prove Anything. Bother.)
% So now we have the following float placement specifiers:
% \begin{table}[H]
% \begin{tabular}{cl}
% \tt t & Top of the page\\
% \tt b & Bottom of the page\\
% \tt p & Page of floats\\
% \tt h & Here, if possible\\
% \tt H & Here, definitely
% \end{tabular}
% ^^A\caption{Could it be that this just needs a caption?}
% \end{table}
%
% \typeout{End of the Introduction.}
% \typein[\answer]%
%   {Do you want an annotated listing of the macro definitions (y/n) ?}
% \def\next{y}\ifx\answer\next\else\expandafter\stop\fi
% \StopEventually{\PrintIndex}
%
% \section{Implementation}
%
% As usual, the file identifies itself in the log file.
% But only if this file's macros aren't yet defined.
% `Old' versions of \LaTeX\ (those before March 1992) don't have |\@Esphack|.
% We do an |\@esphack| hack to get around that.
%    \begin{macrocode}
\@ifundefined{newfloat}{}{\endinput}
\wlog{Style-Option: `float' 1.1c 18 Dec 92 (AL)}
\@ifundefined{@Esphack}{\let\@Esphack\@esphack}{}
%    \end{macrocode}
% In \LaTeX, floats are assigned `type numbers' that are powers of two.
% Since there are only two classes of floats, their type numbers are
% hardwired into the document styles. We need to be somewhat more flexible,
% and thus we initialize a counter to hold the next type number to be
% assigned. This counter will be incremented appropriately later.
%    \begin{macrocode}
\newcount\float@type
\@ifundefined{c@figure}{\float@type=1}{\float@type=4}
%    \end{macrocode}
% To warm up, we'll look at some of the simpler commands first.
% \begin{macro}{\floatstyle}
% The |\floatstyle| command puts its argument into the
% |\float@style| macro as the name of the new float style.
% But if the argument doesn't denote a float style, an error message
% is output instead: Each float style \meta{style} has a corresponding command
% |\fs@|\meta{style} that contains the appropriate declarations.
% If the control sequence |\fs@|\meta{arg} (which goes with the
% argument \meta{arg} to |\floatstyle|) is undefined, i.e.,
% equals |\relax| under |\ifx|, then the float style \meta{arg}
% is unknown, and we call |\float@error{|\meta{arg}|}| for the
% error message.
%    \begin{macrocode}
\def\floatstyle#1{\expandafter\ifx\csname fs@#1\endcsname\relax
  \float@error{#1}\else\def\float@style{#1}\fi}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\float@error}
% Here's the error message. |\@eha| is the help message that says
% `Your command was ignored.'
%    \begin{macrocode}
\def\float@error#1{\@latexerr{Unknown float style `#1'}\@eha}
%    \end{macrocode}
% \end{macro}
%
% The next two commands are even simpler. \LaTeX\ says that
% |\fps@|\meta{float} contains the default placement specifier for
% the class of floats \meta{float}. |\fname@|\meta{float} expands
% to the name that appears in \meta{float} captions, e.g., `Figure'.
% (This is our own definition.)
%    \begin{macrocode}
\def\floatname#1#2{\@namedef{fname@#1}{#2}}
\def\floatplacement#1#2{\@namedef{fps@#1}{#2}}
%    \end{macrocode}
%
% \begin{macro}{\restylefloat}
% The |\restylefloat| command sets up everything so that subsequent
% commands like |\begin{|\meta{float}|}| use the appropriate
% float style. It defines |\fst@|\meta{float} to expand to a command
% that sets up the currently selected float style (|\fs@|\meta{style}).
% Then it defines the commands |\begin{|\meta{float}|}|,
% |\end{|\meta{float}|}|, |\begin{|\meta{float}|*}| and
% |\end{|\meta{float}|*}|.
%    \begin{macrocode}
\def\restylefloat#1{\expandafter\edef\csname
  fst@#1\endcsname{\expandafter\noexpand\csname
    fs@\float@style\endcsname}%
  \@namedef{#1}{\bgroup\@nameuse{fst@#1}\@float{#1}}%
  \@namedef{#1*}{\bgroup\@nameuse{fst@#1}\@dblfloat{#1}}%
  \expandafter\let\csname end#1\endcsname\float@end
  \expandafter\let\csname end#1*\endcsname\float@dblend}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\newfloat}
% Now we can explain how to define a new class of floats. Recall that
% the three required arguments to |\newfloat| are \meta{type},
% \meta{placement} and \meta{ext}, respectively. First we save the
% latter two.
%    \begin{macrocode}
\def\newfloat#1#2#3{\@namedef{ext@#1}{#3}
  \floatplacement{#1}{#2}%
%    \end{macrocode}
% Then we figure out a default value for the `caption name' of this
% class of floats. If the |\fname@|\meta{type} isn't already defined,
% we tentatively use \meta{type} as the name. This is convenient if
% \meta{type} is, say, {\tt Program}, since no |\floatname| command
% is necessary at all.
%    \begin{macrocode}
  \expandafter\ifx\csname fname@#1\endcsname\relax
    \floatname{#1}{#1}\fi
%    \end{macrocode}
% Then we set up the type number for \LaTeX\ in |\ftype@|\meta{type}.
% Afterwards we have to set the |\float@type| to the next greater power
% of two, so that it is ready for the next |\newfloat|. Fortunately,
% we just have to double it by adding. We don't bother to check for overflow
% since it is pretty unlikely that somebody will define 25 different classes
% of floats. Finally, we call |\restylefloat| to define the style and
% commands for this class of floats.
%    \begin{macrocode}
  \expandafter\edef\csname ftype@#1\endcsname{\the\float@type}%
  \advance\float@type by\float@type
  \restylefloat{#1}%
%    \end{macrocode}
% Now all that's left is to assemble the |\fnum@|\meta{type} macro
% that \LaTeX\ wants to use in its captions. Basically it is just
% `caption name'${}+{}$`counter value', disguised so that the command
% {\em names\/} appear in the definition instead of their expansions.
%    \begin{macrocode}
  \expandafter\edef\csname fnum@#1\endcsname%
    {\expandafter\noexpand\csname fname@#1\endcsname{}
       \expandafter\noexpand\csname the#1\endcsname}
%    \end{macrocode}
% Finally, we have to take care of the optional argument, \meta{within}.
% If the optional argument is present, we pass control to |\@xnewfloat|.
% Otherwise, we just define the counter for this class of floats.
% By default, the numbers come out |\arabic|.
%    \begin{macrocode}
  \@ifnextchar[{\@xnewfloat{#1}}%
    {\@ifundefined{c@#1}{\newcounter{#1}\@namedef{the#1}{\arabic{#1}}}%
      {}}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\@xnewfloat}
% Here we deal with the optional argument to |\newfloat|. We have
% to create a new counter as per |\newcounter{|\meta{type}|}|
% and add that counter to the list of counters to be reset whenever
% counter \meta{within} is stepped. The standard command
% |\newcounter{|\meta{type}|}[|\meta{within}{\tt]} takes care of that.
% However, we can't define the \meta{type} counter if it's already defined.
% While this case is simply ignored when \meta{within} is not present,
% we issue a warning here since what comes out is probably not what the user
% expects.
%    \begin{macrocode}
\def\@xnewfloat#1[#2]{\@ifundefined{c@#1}{\newcounter{#1}[#2]%
    \expandafter\edef\csname the#1\endcsname{%
      \expandafter\noexpand\csname
        the#2\endcsname.\noexpand\arabic{#1}}}%
    {\@warning{Can't redefine counter variable for #1.}}}
%    \end{macrocode}
% \end{macro}
% 
% We have to adapt some of \LaTeX's internal macros to our needs.
% There are several things that have to be changed around
% in order to provide the functionality of David Carlisle's {\tt here.sty}.
% The following is thus lifted from {\tt here.sty}, with changes and with
% David's permission:
%
% \begin{macro}{\@Hxfloat}
% We save the original version of |\@xfloat|. (This macro is called from
% |\@float|, which we used above to define the environment commands for a
% new class of floats.)
%    \begin{macrocode}
\let\@Hxfloat\@xfloat
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\@xfloat}
% The new version of |\@xfloat| looks for a |[H]| argument.
% If it is present |\@HHfloat| is called, otherwise the original macro
% (renamed to |\@Hxfloat|) is called.
%    \begin{macrocode}
\def\@xfloat#1[{\@ifnextchar{H}{\@HHfloat{#1}[}{\@Hxfloat{#1}[}}
%    \end{macrocode}
% \end{macro}
% Later on we'll need a box to save a |[H]| float.
%    \begin{macrocode}
\newbox\float@box
\newif\if@flstyle
%    \end{macrocode}
% \begin{macro}{\@HHfloat}
% First gobble the |[H]|. Note that {\tt H} should not be used in
% conjunction with the other placement options, nor as the value of the
% default placement, as set in |\fps@|{\it type}.
%    \begin{macrocode}
\def\@HHfloat#1[H]{%
%    \end{macrocode}
% Locally redefine the end of the environment.
%    \begin{macrocode}
  \expandafter\let\csname end#1\endcsname\float@endH
%    \end{macrocode}
% We don't get a |\@currbox| if we don't actually use the float mechanism.
% Therefore we fake one using the |\float@box| defined above.
%    \begin{macrocode}
  \let\@currbox\float@box
%    \end{macrocode}
% Now we save the current float class name for use in constructing the
% |\caption|. The caption box (defined below) is initialised to an empty
% box to avoid trouble with floats not having a caption. Then we start the
% box that'll hold the float itself.
% |\parindent| is set to zero for compatibility with the standard {\tt [h]}
% option.
%    \begin{macrocode}
  \def\@captype{#1}\setbox\@floatcapt=\vbox{}%
  \expandafter\ifx\csname fst@#1\endcsname\relax
    \@flstylefalse\else\@flstyletrue\fi
  \setbox\@currbox=\vbox\bgroup\parindent\z@
%    \end{macrocode}
% The final |\ignorespaces| is needed to gobble any spaces or newlines
% after the {\tt[H]} tokens.
%    \begin{macrocode}
  \ignorespaces}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\float@makebox}
% Basically, we must arrange for `style commands' to be executed
% at certain points during the generation of the float.
% \LaTeX\ puts a float into a vertical box |\@currbox| which it takes
% off a list of empty boxes for insertions. When the |\float@makebox| macro
% is called, |\@currbox| contains the complete float, minus the caption
% --- we'll see later that we use our own |\caption| command to
% put the caption into a |\vbox| of its own. This is the only way
% we can control the position of the caption by the float style,
% regardless of where the caption appears in the float's input text itself.
% So the `style commands' are |\@fs@pre|, which is inserted at the
% very beginning of the float, |\@fs@mid|, which comes between the
% float and the caption (or the caption and the float, if captions are put
% at the top), and |\@fs@post|, which finishes off the float.
% The caption may appear at the top or at the bottom of the float,
% as defined by |\@fs@iftopcapt|. Therefore, before we hand the
% float to \LaTeX\ for positioning, it is taken apart and reassembled
% using the style commands.
%    \begin{macrocode}
\def\float@makebox{%
  \vbox{\hsize\columnwidth \@parboxrestore
    \@fs@pre\@fs@iftopcapt
      \ifvbox\@floatcapt\unvbox\@floatcapt\par\@fs@mid\fi
      \unvbox\@currbox
    \else\unvbox\@currbox
      \ifvbox\@floatcapt\par\@fs@mid\unvbox\@floatcapt\fi
    \fi\par\@fs@post\vskip\z@}}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\float@end}
% The internal macro |\end@float| appears here under the name of |\float@end|.
% The main thing which is changed is that we call |\float@makebox| to
% reconstruct the float according to the float style.
%    \begin{macrocode}
\def\float@end{\egroup
  \global\setbox\@currbox\float@makebox
%    \end{macrocode}
% Now \LaTeX\ takes over again.
%    \begin{macrocode}
   \ifnum\@floatpenalty <\z@ \@cons\@currlist\@currbox
     \ifdim \ht\@currbox >\textheight 
        \ht\@currbox\textheight \fi
     \ifnum\@floatpenalty < -\@Mii 
        \penalty -\@Miv \@tempdima\prevdepth
        \vbox{}\prevdepth \@tempdima \penalty\@floatpenalty
      \else \vadjust{\penalty -\@Miv
        \vbox{}\penalty\@floatpenalty}\@Esphack
     \fi\fi\egroup}
%    \end{macrocode}
% (The final |\egroup| is not present in the original definition;
% we need it to finish off the |\bgroup| that precedes the
% |\@nameuse| in the |\begin{|\meta{float}|}| commands.
% This is to keep the style commands local.)
% \end{macro}
%
% \begin{macro}{\float@endH}
% The |\float@endH| command is, again, derived from {\tt here.sty}. It'll
% deal correctly with a non-floating float, inserting the proper amounts
% of white space above and below.
%    \begin{macrocode}
\def\float@endH{\egroup \vskip\intextsep
  \if@flstyle\float@makebox\else\box\@currbox\fi
  \vskip\intextsep\egroup}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\float@dblend}
% The |\float@dblend| macro is an almost-verbatim copy of
% |\end@dblfloat| but for the last part, from |\fi\egroup| on.
% The |\egroup| is, of course, necessary because of the |\bgroup|
% at the very beginning of the float. And we have to call |\float@end|
% instead of |\end@float|, naturally.
%    \begin{macrocode}
\def\float@dblend{\if@twocolumn
  \par\vskip\z@\egroup
  \ifnum\@floatpenalty <\z@ \@cons\@dbldeferlist\@currbox\fi
    \ifnum \@floatpenalty =-\@Mii \@Esphack\fi\egroup\else\float@end\fi}
%    \end{macrocode}
% \end{macro}
%
% Now for the caption routines.
% We use a box, |\@floatcapt|, to hold the caption while the float
% is assembled.
%    \begin{macrocode}
\newbox\@floatcapt
%    \end{macrocode}
%
% \begin{macro}{\caption}
% This is the only \LaTeX\ macro that this document style supersedes.
% Our |\caption| command checks whether there is a custom style
% defined for the current float (whose type can be found in |\@captype|).
% If so, the caption routines from {\tt float.sty} are used, otherwise
% we call the vanilla \LaTeX\ routines.
% The |\@flcapt| conditional is used to tell the float-assembly routines
% that there actually {\em is\/} a caption. We need this to properly handle
% {\tt figure}s and {\tt table}s that have been restyled.
%    \begin{macrocode}
\def\caption{\refstepcounter\@captype
  \expandafter\ifx\csname fst@\@captype\endcsname\relax
      \let\@tempf\@caption
    \else\let\@tempf\float@caption\fi \@dblarg{\@tempf\@captype}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\float@caption}
% The |\float@caption| macro takes care of entering the caption into
% the appropriate listing. It also controls the typesetting of the caption
% itself, although a style-dependent macro |\@fs@capt| is called
% to handle the specifics. Note that because the caption is saved in a box
% instead of being output to the float right away, you cannot simply put
% a legend after the caption proper; it has to follow the |\caption|
% command in an optional argument.
%
% First of all, we call |\addcontentsline| to update the list of
% floats of this class. Note that |\float@caption| is |\long|
% to allow for paragraph breaks in its arguments.
%    \begin{macrocode}
\long\def\float@caption#1[#2]#3{\addcontentsline{\csname
  ext@#1\endcsname}{#1}{\protect\numberline{\csname
    the#1\endcsname}{\ignorespaces #2}}
%    \end{macrocode}
% Now we collect the caption proper. The caption name and number are
% taken from |\fnum@|\meta{float}, where \meta{float} is the class
% of float we're currently handling.
%    \begin{macrocode}
  \global\setbox\@floatcapt\vbox\bgroup\@parboxrestore
    \normalsize\@fs@capt{\csname fnum@#1\endcsname}{\ignorespaces #3}%
%    \end{macrocode}
% Finally we check for the presence of the optional argument. If there is
% one, we call |\float@ccon| to pick it up; otherwise, the |\egroup|
% finishes off the box.
%    \begin{macrocode}
    \@ifnextchar[{\float@ccon}{\egroup}}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\float@ccon}
% The |\float@ccon| macro expands to the optional argument of a
% |\caption| command, followed by |\par\egroup|. Note that this
% precludes using |\verb| \& Co.\ in the optional argument; the
% interested reader is urged to fix this problem as an exercise.
%    \begin{macrocode}
\long\def\float@ccon[#1]{#1\par\egroup}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\listof}
% The |\listof| command reads the desired list of floats from the
% appropriate auxiliary file. The file is then restarted.
% Currently the list appears at the chapter or the section level, depending
% on whether chapters are supported in the document style at all.
% First of all, we check whether the float style that's supposed to be
% listed is actually defined. If not, we output a |\float@error|.
%    \begin{macrocode}
\def\listof#1#2{\expandafter\ifx\csname
    ext@#1\endcsname\relax\float@error{#1}%
%    \end{macrocode}
% All's well until now. We determine whether the list is going to be a
% chapter or a section, and we define the |\l@|\meta{float} command
% that \LaTeX\ needs for formatting the list.
% After that, we call |\@starttoc| with the correct file extension
% to do the actual work.
%    \begin{macrocode}
  \else
    \@ifundefined{chapter}{\def\@tempa{\section*}}%
      {\def\@tempa{\chapter*}}%
    \@tempa{#2\@mkboth{\uppercase{#2}}{\uppercase{#2}}}%
    \expandafter\def\csname
      l@#1\endcsname{\@dottedtocline{1}{1.5em}{2.3em}}%
    \@starttoc{\csname ext@#1\endcsname}\fi}
%    \end{macrocode}
% \end{macro}
%
% \section{The Float Styles}
%
% Finally, we define the three standard float styles that were outlined
% in the Introduction. Every float style \meta{style} corresponds to a
% command |\fs@|\meta{style} which contains the definitions of the
% style commands, namely
% \begin{center}\begin{tabular}{rl}
% |\@fs@pre|&top of the float\\
% |\@fs@mid|&between float and caption\\
% |\@fs@post|&bottom of the float\\
% |\@fs@capt|&formatting routine for caption\\
% |\@fs@cfont|&font for caption name \& number
% \end{tabular}\end{center}
%
% \begin{macro}{\floatc@plain}
% The |\floatc@plain| macro formats a caption the way \LaTeX\ does
% it: if the caption is fairly short, it is centered, otherwise it is
% formatted as a paragraph. The only difference is that the portion
% containing the caption name and number uses the |\@fs@captfont|.
%    \begin{macrocode}
\def\floatc@plain#1#2{\setbox\@tempboxa\hbox{{\@fs@cfont #1:} #2}%
  \ifdim\wd\@tempboxa>\hsize {\@fs@cfont #1:} #2\par
    \else\hbox to\hsize{\hfil\box\@tempboxa\hfil}\fi}
%    \end{macrocode}
% \end{macro}
% \begin{macro}{\fs@plain}
% The {\tt plain} float style is similar to what \LaTeX\ does of its
% own accord; the only difference is that the caption is guaranteed
% to come out at the bottom of the float.
%    \begin{macrocode}
\def\fs@plain{\def\@fs@cfont{\rm}\let\@fs@capt\floatc@plain
  \def\@fs@pre{}\def\@fs@post{}\def\@fs@mid{\vskip10pt\relax}%
  \let\@fs@iftopcapt\iffalse}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\floatc@ruled}
% The |\floatc@ruled| command is even simpler than the
% |\floatc@plain| macro. The caption is simply printed `as is'.
%    \begin{macrocode}
\def\floatc@ruled#1#2{{\@fs@cfont #1} #2\par}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\fs@ruled}
% In the {\tt ruled} float style, the caption appears at the top of the
% float, preceded and followed by horizontal rules.
% Another rule followes the whole of the float.
%    \begin{macrocode}
\def\fs@ruled{\def\@fs@cfont{\bf}\let\@fs@capt\floatc@ruled
  \def\@fs@pre{\hrule height.8pt depth0pt \kern2pt}%
  \def\@fs@post{\kern2pt\hrule\relax}%
  \def\@fs@mid{\kern2pt\hrule\kern2pt}%
  \let\@fs@iftopcapt\iftrue}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\fs@boxed}
% The {\tt boxed} float style puts the float into a box (which is slightly
% larger than the usual |\textwidth|). The caption appears below
% the box.
%    \begin{macrocode}
\@namedef{fs@boxed}{\def\@fs@cfont{\bf}\let\@fs@capt\floatc@plain
  \def\@fs@pre{\dimen0=\hsize \advance\dimen0 by6.8pt \hbadness10000
    \moveleft3.4pt\vbox\bgroup\hsize=\dimen0\hrule
      \hbox to\dimen0\bgroup\vrule\kern3pt\vbox\bgroup\kern3pt}%
  \def\@fs@mid{\kern3pt\egroup\kern3pt\vrule\egroup
    \hrule\egroup\kern2pt}%
  \def\@fs@post{}\let\@fs@iftopcapt\iffalse}
%    \end{macrocode}
% \end{macro}
%
% Before we finish, we set the float style to {\tt plain}.
%    \begin{macrocode}
\floatstyle{plain}
%    \end{macrocode}
% Other float styles can be added without much ado.
% If there are many more float styles, it should be worthwhile
% to invent a scheme similar to that used in Frank Mittelbach's
% {\tt theorem} option in order to conserve space, i.e., put the
% float styles into individual files that can be loaded on demand.
% I would like to hear from people who define interesting
% float styles.
% \Finale
% \end{document}
\endinput