Cfrgtkky

Is it possible to capture the contents to the end-of-line as a macro argument?

For example, consider the following naive visualization:

documentclass{article}

newenvironment{myitemize}

  {defitem{textbullet }}

  {}

begin{document}

begin{myitemize}

  item First

  item Second

  item Third

  item Last

end{myitemize}

end{document}

I'd like to define item using something like

defitem#1par{<do stuff with #1>}

but this requires an empty line between items to pick up par:

documentclass{article}

newenvironment{myitemize}

  {defitem##1par{textbullet ##1par}}

  {}

begin{document}

begin{myitemize}

  item First



  item Second



  item Third



  item Last



end{myitemize}

end{document}

Looking at obeylines in latex.ltx I thought this may have something to do with ^^M, but I'm not sure how I can incorporate that into the definition of item.

You can use environ:

documentclass{article}

usepackage{environ}



makeatletter

NewEnviron{myitemize}{%

  defitem##1item{dosomething{##1}}%

  expandafter@emptyBODYitem}



newcommand{dosomething}[1]{%

  defwerner@arg{#1}%

  ifxwerner@argwerner@stop

    expandafterenv@ignore   % to end the recursion

  else

    ``Here is #1unskip''par % what to do with #1

    expandafteritem         % to continue the recursion

  fi}



edefwerner@stop{noexpandenv@ignorespace}

makeatother

begin{document}



begin{myitemize}

  item First

  item Second

  item Last

end{myitemize}



end{document}

Note that end{myitemize} should go on a line of its own (one could also take care of it appearing on the same line as the last item). The unskip is necessary if par is not next to #1 or isn't used at all, because of the end of line at the end of the item text.

A much more powerful implementation with expl3:

documentclass{article}

usepackage{xparse}



ExplSyntaxOn

NewDocumentEnvironment{myitemize}{ O{} +b }

 {

  % do the setup

  keys_set:nn { werner/itemize } { #1 }

  % split the contents at item

  seq_set_split:Nnn l_werner_itemize_input_seq { item } { #2 }

  % remove the first (empty) item

  seq_pop_left:NN l_werner_itemize_input_seq l_tmpa_tl

  % issue the preamble

  tl_use:N l_werner_itemize_pre_tl

  % adorn the items

  seq_set_map:NNn

    l_werner_itemize_output_seq

    l_werner_itemize_input_seq

    { exp_not:n { __werner_itemize_do:n { ##1 } } }

  % output the items, separated by the chosen separator

  seq_use:NV l_werner_itemize_output_seq l_werner_itemize_sep_tl

  % issue the postamble

  tl_use:N l_werner_itemize_post_tl

 }

 {}



seq_new:N l_werner_itemize_input_seq

seq_new:N l_werner_itemize_output_seq

cs_generate_variant:Nn seq_use:Nn { NV }



keys_define:nn { werner/itemize }

 {

  pre    .tl_set:N  = l_werner_itemize_pre_tl,

  post   .tl_set:N  = l_werner_itemize_post_tl,

  sep    .tl_set:N  = l_werner_itemize_sep_tl,

  action .code:n    = cs_set_eq:NN __werner_itemize_do:n #1,

  action .initial:n = use:n,

 }

ExplSyntaxOff



NewDocumentCommand{quotepar}{m}{%

  ``#1''par

}

NewDocumentCommand{normalitem}{m}{%

  item #1

}

NewDocumentCommand{bulletitem}{m}{%

  textbullet #1%

}



begin{document}



begin{myitemize}[action=bulletitem,sep={, }]

  item First

  item Second

  item Last

end{myitemize}



begin{myitemize}[action=quotepar]

  item First

  item Second

  item Last

end{myitemize}



begin{myitemize}[

  action=normalitem,

  pre=begin{itemize},

  post=end{itemize},

]

  item First

  item Second

  item Last

end{myitemize}



end{document}