% \iffalse
%%
%% File: dcounter.dtx Copyright (C) 1998 Alexander Rozhenko
%%
%<package>\NeedsTeXFormat{LaTeX2e}
%<package>\ProvidesPackage{dcounter}
%<package>      [1998/12/19 v1.0 Dynamic Counters Package (NCC)]
%
% \changes{v1.0}{1998/12/19}{Initial version}
%
%<*driver>
\documentclass{ltxdoc}
\usepackage{dcounter}
\GetFileInfo{dcounter.sty}
\begin{document}
\title{The \textsf{dcounter} package\thanks{This file
        has version number \fileversion, last
        revised \filedate.}}
\author{Alexander Rozhenko\\rozhenko@oapmg.sscc.ru}
\date{\filedate}
\maketitle
\DocInput{dcounter.dtx}
\end{document}
%</driver>
% \fi
% This package implements a concept of \emph{dynamic counters}. The
% counter declared as dynamic is really created at the first use
% and recieves at that moment the \emph{count style} which was
% established by the |\countstyle| command. For example,
% if |\countstyle{section}| is established, all dynamically created
% counters will be subordinated to |section| counter (i.e., resetted
% to zero when |section| counter is stepped) and their typesetting
% command |\the|\emph{foo} will be equal to
% |\thesection.\arabic{|\emph{foo}|}|. This package is compartible with
% |calc| package.
%
% \section{User Interface}
%
% \DescribeMacro\DeclareDynamicCounter
% To declare new dynamic counter \meta{foo} you have to write
% \begin{quote}
%    |\DeclareDynamicCounter|\marg{foo}
% \end{quote}
% The counter \meta{foo} will be added to the list of dynamic counters
% and could be created later at the first usage by one of the following
% commands
% \begin{tabbing}
% |     \setcounter|\marg{foo}\marg{number}\qquad\qquad\=
%      |\stepcounter|\marg{foo}\\
% |     \addtocounter|\marg{foo}\marg{number}\>
%      |\refstepcounter|\marg{foo}
% \end{tabbing}
%
% \DescribeMacro\countstyle
% To order a count style you have to use the command
% \begin{quote}
%    |\countstyle|\marg{counter}
% \end{quote}
% The parameter \meta{counter} have to be existing counter, or dynamic
% counter, or empty. Empty \meta{counter} means the \emph{plain} count
% style without subordination. If \meta{counter} not exists and is
% dynamic it is created here within the previously ordered count style.
% The default count style is plain style.
%
% The |\counstyle| command has an optional parameter useful for
% special purposes. If you want to create some counters in another style
% that is ordered by |\countstyle| command, you could write
% \begin{quote}
%    |\countstyle[|\meta{list of counters}|]|\marg{another counter}
% \end{quote}
% Here \meta{list of counters} is the list of comma separated counters
% whose count style you want to subordinate to
% \meta{another counter}. This command creates all undefined counters of
% the list. The list may contain not only undefined counters but also
% the existing counters. If counter in the list
% does exist, its count style will be modified to be subordinated to
% \meta{another counter}. Note, that if this counter was subordinated
% before to any other counter, \emph{the previous subordination will be
% rejected}. For example, let we want to use the |book| document class
% and set the |\Roman| enumeration of chapters, the independent arabic
% enumeration of sections and to subordinate the enumeration of figures,
% tables and equations to \emph{section} counter. We can write
% \begin{quote}
%    |\documentclass{book}|\\
%    |\usepackage{dcounter}|\\
%    |\renewcommand\thechapter{\Roman{chapter}}|\\
%    |\countstyle[section]{}|\\
%    |\countstyle[figure,table,equation]{section}|
% \end{quote}
% After that the \emph{chapter} counter will not affect to
% \emph{section} counter and all figure, table, and equation numbers
% will typeset as |\thesection.\arabic{|\emph{foo}|}|.
%
% \DescribeMacro\DynamicCount
% The command
% \begin{quote}
%    |\DynamicCount|\marg{counter}
% \end{quote}
% sets the count style for \meta{counter} exactly the same as for
% dynamically created counters and creates this counter if it is
% undefined. Where this command may be used?
% Suppose that we want to set within a package the dynamic enumeration
% style for equations, e.g. allow user to set count style wanted and
% after then modify the style of \emph{equation} counter dynamically.
% The following commands used within a package do this job:
% \begin{quote}
%    |\let\theequation\relax|\\
%    |\AtBeginDocument{|\\
%    |  \ifx\theequation\relax \DynamicCount{equation}\fi}|
% \end{quote}
%
% \textbf{Note}. All described commands may be used only in the
% preamble of the document.
%
% \StopEventually{}
%
% \section{The Basic Implementation Part}
%
% \begin{macro}{\DCNT@list}
% We begin from the initialization of the list of dynamic counters
%    \begin{macrocode}
\def\DCNT@list{}
%    \end{macrocode}
% Its items will have the form |\@elt|\marg{counter}
% \end{macro}
%
% \begin{macro}{\DCNT@in}
% The macro |\DCNT@in|\marg{list}\marg{yes}\marg{no}
% tests the list of counters \meta{list} to contain the counter
% |\DCNT@foo| and after testing execites \meta{yes}-sequence if
% |\DCNT@foo| found or \meta{no}-sequence if not. To restrict
% the scope of internal modifications made by this macro we allways
% enclose it into a group. While processing the list of counters the
% command executes |\DCNT@noteq|\marg{counter} hook for every
% counter which name is distinct from the tested name.
%    \begin{macrocode}
\def\DCNT@in#1#2#3{\@tempswafalse
  \let\@elt\DCNT@elt #1%
  \if@tempswa #2\else #3\fi
}
\def\DCNT@elt#1{\def\DCNT@name{#1}%
  \ifx\DCNT@name\DCNT@foo \@tempswatrue \else \DCNT@noteq{#1}\fi
}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\DCNT@define}
% The command |\DCNT@define|\marg{command}\marg{foo}
% tests the counter \meta{foo} to be undefined and, if it is true,
% tries to create it dynamically. After that it executes \meta{command}
% with the \meta{foo} parameter.
%    \begin{macrocode}
\def\DCNT@define#1#2{%
  \@ifundefined{c@#2}%
    {{\edef\DCNT@foo{#2}\let\DCNT@noteq\@gobble
      \DCNT@in\DCNT@list{\newcounter{#2}\DCNT@the{#2}}{}%
    }}{}%
  #1{#2}%
}
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\DCNT@the}
% The command |\DCNT@the|\marg{foo} redefines |\the|\meta{foo}
% command to typeset it in the count style subordinated to |\DCNT@main|
% counter. It also adds the name \meta{foo} to the resetting list of\/
% |\DCNT@main| counter.
%    \begin{macrocode}
\def\DCNT@the#1{%
  \ifx\DCNT@main\@empty
    \expandafter\xdef\csname the#1\endcsname
      {\noexpand\@arabic \expandafter\noexpand \csname c@#1\endcsname}%
  \else
    \expandafter\xdef\csname the#1\endcsname
      {\expandafter\noexpand \csname the\DCNT@main\endcsname
      .\noexpand\@arabic \expandafter\noexpand \csname c@#1\endcsname}%
    \@addtoreset{#1}\DCNT@main
  \fi
}
\let\DCNT@main\@empty
%    \end{macrocode}
% \end{macro}
%
% \section{The Preamble Only Commands}
%
% \begin{macro}{\DeclareDynamicCounter}
% The following command tests the counter to be existing and adds it
% to the list of dynamic counters if it doesn't exist.
%    \begin{macrocode}
\newcommand*{\DeclareDynamicCounter}[1]{%
  \@ifundefined{c@#1}%
    {{\edef\DCNT@foo{#1}\let\DCNT@noteq\@gobble
      \ifx\DCNT@foo\@empty
         \PackageError{dcounter}%
           {You try to declare an empty dynamic counter}{}%
      \fi
      \DCNT@in\DCNT@list{}{\@cons\DCNT@list{{#1}}}%
    }}{}%
}
\@onlypreamble\DeclareDynamicCounter
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\countstyle}
% Now we implement |\countstyle| command which redefines |\DCNT@main|
% macro to new main counter. It tests the counter to be defined and
% tries to define it if\/ not.
%    \begin{macrocode}
\newcommand{\countstyle}{\@ifnextchar[{\DCNT@lcstyle}{\DCNT@cstyle}}
\@onlypreamble\countstyle
\def\DCNT@cstyle#1{\edef\DCNT@foo{#1}%
  \ifx\DCNT@foo\@empty \else
    \DCNT@define\@gobble{#1}%
    \@ifundefined{c@#1}{\@nocounterr{#1}}{}%
  \fi
  \let\DCNT@main\DCNT@foo
}
\@onlypreamble\DCNT@cstyle
%    \end{macrocode}
% The special variant of this command with optional parameter locally
% sets the special count style and redefines all counters in list via
% the |\DynamicCount| command.
%    \begin{macrocode}
\def\DCNT@lcstyle[#1]#2{%
  {\DCNT@cstyle{#2}\@for\@tempa:=#1\do{\DynamicCount\@tempa}}%
}
\@onlypreamble\DCNT@lcstyle
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\DynamicCount}
% The macro |\DynamicCount|\marg{foo} modifies the count style of
% the counter \meta{foo} and defines this counter if it is undefined.
%    \begin{macrocode}
\newcommand*{\DynamicCount}[1]{%
  \@ifundefined{c@#1}%
    {\newcounter{#1}}%
%    \end{macrocode}
% If the counter is already defined, we check all resetting lists and
% remove all references to this counter.
%    \begin{macrocode}
    {{\edef\DCNT@foo{#1}\let\DCNT@noteq\DCNT@add
      \let\@elt\DCNT@remove \cl@@ckpt
    }}%
  \DCNT@the{#1}%
}
\@onlypreamble\DynamicCount
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\DCNT@remove}
% The command |\DCNT@remove|\marg{foo} removes all references
% to |\DCNT@foo| counter from the |\cl@|\meta{foo} list of counters.
%    \begin{macrocode}
\def\DCNT@remove#1{\expandafter\DCNT@remlist\csname cl@#1\endcsname}
\def\DCNT@remlist#1{%
  {\let\@tempa\@empty \DCNT@in#1{\global\let#1\@tempa}{}}%
}
\@onlypreamble\DCNT@remove
\@onlypreamble\DCNT@remlist
%    \end{macrocode}
% \end{macro}
%
% \begin{macro}{\DCNT@add}
% The command |\DCNT@add|\marg{counter} locally adds
% |\@elt|\marg{counter} to |\@tempa|.
%    \begin{macrocode}
\def\DCNT@add#1{%
  \let\@elt\relax\edef\@tempa{\@tempa\@elt{#1}}\let\@elt\DCNT@elt
}
\@onlypreamble\DCNT@add
%    \end{macrocode}
% \end{macro}
%
% \section{Final Modifications}
%
% Finally, we modify |\setcounter| and |\addtocounter| commands.
% We do it at the beginning of the document to avoid conflict with
% the |calc| package. If\/ the list of dynamic counters is empty,
% we delete all commands of the package.
%    \begin{macrocode}
\AtBeginDocument{%
  \ifx\DCNT@list\@empty
    \@onlypreamble\DCNT@list
    \@onlypreamble\DCNT@in
    \@onlypreamble\DCNT@elt
    \@onlypreamble\DCNT@define
    \@onlypreamble\DCNT@the
    \@onlypreamble\DCNT@main
    \@onlypreamble\DCNT@name
    \@onlypreamble\DCNT@foo
    \@onlypreamble\DCNT@noteq
  \else
    \let\DCNT@setcounter\setcounter
    \def\setcounter{\DCNT@define\DCNT@setcounter}
    \let\DCNT@addtocounter\addtocounter
    \def\addtocounter{\DCNT@define\DCNT@addtocounter}
  \fi
}
%    \end{macrocode}
\endinput