% \iffalse meta-comment
%
%% File: l3legacy.dtx
%
% Copyright (C) 2019 The LaTeX3 Project
%
% It may be distributed and/or modified under the conditions of the
% LaTeX Project Public License (LPPL), either version 1.3c of this
% license or (at your option) any later version.  The latest version
% of this license is in the file
%
%    https://www.latex-project.org/lppl.txt
%
% This file is part of the "l3kernel bundle" (The Work in LPPL)
% and all files in that bundle must be distributed together.
%
% -----------------------------------------------------------------------
%
% The development version of the bundle can be found at
%
%    https://github.com/latex3/latex3
%
% for those people who are interested.
%
%<*driver>
\documentclass[full,kernel]{l3doc}
\begin{document}
  \DocInput{\jobname.dtx}
\end{document}
%</driver>
% \fi
%
% \title{^^A
%   The \textsf{l3legacy} package\\ Interfaces to legacy concepts^^A
% }
%
% \author{^^A
%  The \LaTeX3 Project\thanks
%    {^^A
%      E-mail:
%        \href{mailto:latex-team@latex-project.org}
%          {latex-team@latex-project.org}^^A
%    }^^A
% }
%
% \date{Released 2019-10-11}
%
% \maketitle
%
% \begin{documentation}
%
% There are a small number of \TeX{} or \LaTeXe{} concepts which are not used
% in \pkg{expl3} code but which need to be manipulated when working as a \LaTeXe{}
% package. To allow these to be integrated cleanly into \pkg{expl3} code, a set
% of legacy interfaces are provided here.
%
% \begin{function}[EXP,pTF]{\legacy_if:n}
%   \begin{syntax}
%     \cs{legacy_if:nTF} \Arg{name} \Arg{true code} \Arg{false code}
%   \end{syntax}
%   Tests if the \LaTeXe{}/plain \TeX{} conditional (generated by \tn{newif})
%   if \texttt{true} or \texttt{false} and branches accordingly. The
%   \meta{name} of the conditional should \emph{omit} the leading \texttt{if}.
% \end{function}
%
% \end{documentation}
%
% \begin{implementation}
%
% \section{\pkg{l3legacy} Implementation}
%
%    \begin{macrocode}
%<*package>
%    \end{macrocode}
%
%    \begin{macrocode}
%<@@=legacy>
%    \end{macrocode}
%
% \begin{macro}[EXP,pTF]{\legacy_if:n}
%   A friendly wrapper.
%    \begin{macrocode}
\prg_new_conditional:Npnn \legacy_if:n #1 { p , T , F , TF }
  {
    \exp_args:Nc \if_meaning:w { if#1 } \iftrue
      \prg_return_true:
    \else:
      \prg_return_false:
    \fi:
  }
%    \end{macrocode}
% \end{macro}
%
%    \begin{macrocode}
%</package>
%    \end{macrocode}
%
% \end{implementation}
%
% \PrintIndex
