DOI package for abbrvnat.bst

doi.sty

\NeedsTeXFormat{LaTeX2e}
\ProvidesPackage{doi}[2018/09/09 handle doi numbers]

\RequirePackage{hyperref}


%% To change the default prefix, redefine this command within your own code.
%% It takes no argument, which is different from the doipubmed package.
%\newcommand{\doitext}{}

%% To change the default DOI URL resoloution URL, redefine this command
%% within your own code.
%% Previous versions of this package always used http://dx.doi.org/ but
%% The preferred address is now as given here, https://doi.org/
\newcommand{\doiurl}{https://doi.org/}

%% The meat of the code.
%% The first command opens a group, and changes a few catcodes.
\newcommand*{\doi}{% 
  \begingroup 
  \lccode`\~=`\#\relax 
  \lowercase{\def~{\#}}%
  \lccode`\~=`\_\relax
  \lowercase{\def~{\_}}%
  \lccode`\~=`\<\relax 
  \lowercase{\def~{\textless}}%
  \lccode`\~=`\>\relax 
  \lowercase{\def~{\textgreater}}%
  \lccode`\~=0\relax 
  \catcode`\#=\active 
  \catcode`\_=\active 
  \catcode`\<=\active 
  \catcode`\>=\active 
  \@doi
}

%% This is the actual command which processes the argument, with the catcodes 
%% set in the previous command
%% it closes the group, and spits out the url.
\def\@doi#1{% 
  \let\#\relax
  \let\_\relax
  \let\textless\relax 
  \let\textgreater\relax 
  \edef\x{\toks0={{\doiurl#1}}}% 
  \x
  \edef\#{\@percentchar23}%
  \edef\_{_}%
  \edef\x{\toks2={\noexpand\href{\doiurl#1}}}% 
  \x
  \edef\x{\endgroup\the\toks2 \the\toks0}%
  \x
}

%% That's all folks.
\endinput