Xrhrft

I need a command which removes all following tokens which are digits, comma, spaces or newlines and stops if it encounters something else. I can do it by nesting a lot of peek_charcode_remove_ignore_spaces:NTF, but is there a more elegant way to map e.g. over a clist?

documentclass{article}

usepackage{expl3}

ExplSyntaxOn

clist_const:Nnc_uf_page_clist{1,2,3,4,5,6,7,8,9,0,{,}}

cs_new:Nnuf_eatline: {

   peek_charcode_remove_ignore_spaces:NTF 0 { uf_eatline: }

    {

     peek_charcode_remove_ignore_spaces:NTF 1 { uf_eatline: }

      {

       peek_charcode_remove_ignore_spaces:NTF 6 { uf_eatline: }

        {

         peek_charcode_remove_ignore_spaces:NTF , { uf_eatline: }

         { 

          %and more nesting ...          

         }

        }      

      } 

    }

}



cs_set_eq:NNeatlineuf_eatline:

ExplSyntaxOff

newcommandsee[2]{, emph{see} #1}

begin{document}



begin{itemize}

item Textaeatline116, 

153

item Textbeatlinesee{Texta}{162}

end{itemize}



Wanted output:

begin{itemize}

item Texta



item Textbsee{Texta}{162}

end{itemize}





end{document}

If you don't expect eatline to be called inside a group ending with } and you want to skip spaces, you can grab the next token(s) as an argument, examine it and decide.

documentclass{article}

usepackage{xparse}



ExplSyntaxOn

NewDocumentCommand{eatline}{m}

 {

  uf_eatline:n { #1 }

 }



cs_new_protected:Nn uf_eatline:n

 {

  regex_match:nnTF { [0-9,] } { #1 }

   {

    uf_eatline:n

   }

   { #1 }

 }

ExplSyntaxOff



newcommandsee[2]{, emph{see} #1}



begin{document}



begin{itemize}

item Textaeatline116, 

153

item Textbeatlinesee{Texta}{162}

end{itemize}



Wanted output:

begin{itemize}

item Texta



item Textbsee{Texta}{162}

end{itemize}



end{document}

If the token is not a digit or a comma, it is reinserted back, otherwise another token is examined.

Something like {abc} would be reinserted without braces, but it doesn't seem a problem in this context.

The problem with } could be treated at the beginning with a single peek_catcode:NTF check.

If you're not going to have page numbers larger than 2^31-1 then this might work.

The uf_eatline: command starts a group, then sets the catcode of ,, , and ^^M to 9, then uses a primitive integer assignment to consume the remaining numbers (expanding tokens in this process) until something that is not a number is found. Finally, the catcodes are put back to normal with afterassignmentendgroup. This should work even if no numbers follow the eatline function and in the {Whatevereatline} case that egreg mentioned.

documentclass{article}

usepackage{expl3}



ExplSyntaxOn



cs_set_eq:NN uf_after_assignment:N tex_afterassignment:D

int_new:N l_uf_tmpa_int

cs_new:Nn uf_eatline:

  {

    group_begin:

      char_set_catcode_ignore:n { `, }

      char_set_catcode_ignore:n { `  }

      char_set_catcode_ignore:n { `^^M }

      tex_endlinechar:D = 32

      uf_after_assignment:N

    group_end:

      l_uf_tmpa_int = 0

  }



cs_set_eq:NNeatlineuf_eatline:

ExplSyntaxOff



newcommandsee[2]{, emph{see} #1}

begin{document}



begin{itemize}

item Textaeatline116, 

153

item Textbeatlinesee{Texta}{162}

end{itemize}



Wanted output:

begin{itemize}

item Texta



item Textbsee{Texta}{162}

end{itemize}



end{document}