% The example package -- linguistic examples for a messy world
% Copyright 2002-2007, Chung-chieh Shan

% This linguistic examples package has the following virtues.
%
%   - The examples typeset mimic the horizontal and vertical spacing of
%     displayed equations and are numbered together with them.
%
%   - Both examples and sub(sub)examples support \label and \ref.  Two new
%     counters "subequation" and "subsubequation" are defined to this end.
%
%   - Numbering is independent of layout, so for instance you can put
%     multiple subexamples on a single line, or anywhere else.
%
%   - You can specify your own list of columns for tabular alignment, for
%     instance to put an aligned equation to the right of each example.
%     By default, page breaks are permitted between examples but not
%     subexamples.
%
% By default, labels are produced in the form "(1)", "a.", and "i.", and
% references are in the form "1ai".  You can specify your own label format
% by renewing the commands \the(sub(sub))equation, or your own reference
% format by renewing the commands \tag(sub(sub))equation.
%
% Currently, this package does not contain macros for parallel glosses.
% They may be added in the future as an independent feature or package.
% Yay modularity!

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{example}[2007/09/04 LaTeX2e package for linguistics examples]
\RequirePackage{tabularx}
\RequirePackage{mdwtab1}
\RequirePackage{wokluwer}

% Define new counters "subequation" and "subsubequation", for linguistic
% examples numbered like "27bii".  Also define commands "\tagequation",
% "\tagsubequation", and "\tagsubsubequation", to render these counters
% into "(27)", "b.", and "ii." respectively by default.
%
\newcounter{subequation}[equation]
\newcounter{subsubequation}[subequation]
\renewcommand\thesubequation{\theequation\@alph\c@subequation}
\renewcommand\thesubsubequation{\thesubequation\@roman\c@subsubequation}
\newcommand{\tagequation      }{\hb@xt@\leftmargini{(\theequation   )\hfil}}
\newcommand{\tagsubequation   }{\hb@xt@ 1em{\@alph \c@subequation   .\hfil}\kern\labelsep}
\newcommand{\tagsubsubequation}{\hb@xt@ 1em{\@roman\c@subsubequation.\hfil}\kern\labelsep}
\providecommand{\theHsubequation   }{\theHequation\alph{subequation}}
\providecommand{\theHsubsubequation}{\theHsubequation\arabic{subsubequation}}

% Define shortcuts for incrementing and typesetting equation and
% sub(sub)equation numbers.  These can be redefined by the user.
%
\newcommand{\ex}{\refstepcounter{equation}\tagequation}
\newcommand{\ey}{\refstepcounter{subequation}\tagsubequation}
\newcommand{\ez}{\refstepcounter{subsubequation}\tagsubsubequation}

% Define a new command "\subexamples" (and synonymously "\subsubexamples"),
% which uses the tabularx environment to typeset a table that fills up all
% available horizontal space.  For instance, since the default column
% specification is "l@{}X", \subexamples{a.\;&foo\\b.\;&bar} typesets two
% linguistic examples inside an hbox.
%
% Also define "\examples", which is just like "\subexamples" but performs
% the typesetting in vertical mode.  It allows line breaks in the middle of
% the table, and adds the amount of vertical space surrounding display
% equations.
%
\newif\ifexample@intable  % whether we are currently in \(sub(sub))examples
\newif\ifexample@toptable % whether we are at the very first table cell
\newcommand{\subexamples}[2][l@{}X]{%
    \vtop{%
        \noindent
        \example@intabletrue
        \withoutkluwertabular
        \begin{tabularx}{\linewidth}[t]{@{}#1@{}}%
          \example@toptabletrue
          \ignorespaces #2%
        \end{tabularx}}%
    \ignorespaces}
\let\subsubexamples\subexamples
\newcommand{\examples@lrerror}{%
    \PackageError{example}{Cannot display examples in LR mode}{%
      You asked with \string\examples for examples to be displayed,^^J
      but it is impossible in LR (restricted horizontal) mode}}
\newcommand{\examples}[2][l@{}X]{%
  \begingroup
    % Make sure we are not in LR mode.
    \ifhmode \ifinner \examples@lrerror \fi \fi
    % For text-like vertical spacing, disable mdwtab's \tabstyle,
    % \extrarowheight, \tabextrasep, and \arrayextrasep
    \let\tabstyle\relax
    \def\next##1{\ifx##1\@undefined \else ##1\z@ \fi}%
    \next\extrarowheight \next\tabextrasep \next\arrayextrasep
    % Try to detect LaTeX2e's fleqn option (and not AMSLaTeX's)
    % and simulate how it overrides \abovedisplayskip and \belowdisplayskip.
    \ifx\@undefined\mathindent\else \ifx\@undefined\@fleqntrue
      \abovedisplayskip\topsep
      \if@tempswa\else \advance\abovedisplayskip\partopsep \fi
      \advance\abovedisplayskip\parskip
      \belowdisplayskip\abovedisplayskip
    \fi \fi
    % Work around Kluwer's reckless overriding of the tabular environment.
    \withoutkluwertabular
    \example@intabletrue
    % Allow amsmath's \intertext as an alias for mdwtab's \tabpause.
    \let\intertext\tabpause
    \begin{tabularx}{\linewidth}[L]{@{}#1@{}}%
      \example@toptabletrue
      \ignorespaces #2%
    \end{tabularx}%
  \endgroup
  \ignorespaces}

% Define a command "examplebody", for the body text of examples.
%
\newcommand{\examplebody}[1]{%
    \begin{minipage}[t]{\linewidth}%
        \example@intablefalse
        \noindent \ignorespaces #1%
        \@finalstrut \@arstrutbox
    \end{minipage}%
}

% Define commands \example, \subexample, and \subsubexample, which take
% a single argument and typesets it as example text.  These macros detect
% whether they are used within \(sub(sub))examples; if not, they enclose
% themselves within one.
%
\newcommand{\ample@}[4]{%
    \ifexample@intable
        \ifexample@toptable\else#2\fi
        #3\global\let\example@currentlabel\@currentlabel
        &\let\@currentlabel\example@currentlabel \examplebody{#4}\cr
    \else
        #1{\ample@\relax{#2}{#3}{#4}}%
    \fi}
\newcommand{\example@jot}{\noalign{\addvspace\jot}}
\newcommand{\example}{\ample@\examples\example@jot\ex}
\newcommand{\subexample}{\ample@\subexamples\relax\ey}
\newcommand{\subsubexample}{\ample@\subsubexamples\relax\ez}

% Define \< as an abbreviation for \llap, for grammaticality judgments such
% as \<* and \<{??}.
%
\newcommand{\<}[1]{\leavevmode\llap{#1}\ignorespaces}