Argthtjtr

I'm looking for a solution that checks if "alien characters" are contained in a string.

I found Check if a string contains a given character, which looks for one character only. However, I can't adopt this to my needs.

I.E.: Let the main string be asdf.

check{asdf}{asdfgh} should return true, because my main string is a true subset of my string asdfgh which contains non-alien characters.

check{asdf}{hgfdsa} should return true, too. Same as check{adfs}{hdagsf} - Sequence of chars doesn't matter, only occurence.

check{asdf}{asdghj} should return false, because the f character in main string is an alien as it is not in asdghj.

Any ideas welcome.

documentclass{article}



usepackage{xinttools}



makeatletter

newcommandmycheck[2]{%

   xintFor*##1in{#1}:

   {%

      in@{##1}{#2}%

      unlessifin@expandafterxintBreakForfi

   }%

   ifin@expandafter@firstoftwoelseexpandafter@secondoftwofi

}

makeatother



newcommandtest[2]{#1 in #2 ? mycheck{#1}{#2}{TRUE}{FALSE}}

begin{document}



test{asdf}{asdfgh}



test{asdf}{hgfdsa}



test{asdf}{asdghj}

end{document}

You can test each item in the first string for being in the second string; at any “non match” stop and return false.

documentclass{article}

usepackage{xparse}



ExplSyntaxOn



NewDocumentCommand{checkTF}{mmmm}

 {

  stringchecker_if_string_in:nnTF { #1 } { #2 } { #3 } { #4 }

 }



bool_new:N l__stringchecker_temp_bool



prg_new_protected_conditional:Nnn stringchecker_if_string_in:nn { T, F, TF }

 {

  % set the temporary boolean to true; it will remain such

  % unless a nonmatch will happen

  bool_set_true:N l__stringchecker_temp_bool

  % map over the substring to find

  str_map_inline:nn { #1 }

   {

    % do nothing if there is a match; ##1 is the current item, #2 the string to search in

    str_if_in:nnF { #2 } { ##1 }

     {

      % a nonmatch breaks the mapping and sets the boolean to false

      str_map_break:n { bool_set_false:N l__stringchecker_temp_bool }

     }

   }

  bool_if:NTF l__stringchecker_temp_bool

   {% there was no nonmatch, return true

    prg_return_true:

   }

   {% a nonmatch was found, return false

    prg_return_false:

   }

 }

ExplSyntaxOff



begin{document}



checkTF{asdf}{asdfgh}{TRUE}{FALSE}



checkTF{asdf}{hgfdsa}{TRUE}{FALSE}



checkTF{asdf}{asdghj}{TRUE}{FALSE}



checkTF{}{asdghj}{TRUE}{FALSE}



checkTF{a}{}{TRUE}{FALSE}



end{document}

A slightly more efficient version that absorbs one token at a time from the first argument.

documentclass{article}

usepackage{xparse}



ExplSyntaxOn



NewDocumentCommand{checkTF}{mmmm}

 {

  stringchecker_if_string_in:nnTF { #1 } { #2 } { #3 } { #4 }

 }



prg_new_protected_conditional:Nnn stringchecker_if_string_in:nn { T, F, TF }

 {

  __stringchecker_check:nN { #2 } #1 q_nil

 }



cs_new_protected:Nn __stringchecker_check:nN

 {

  quark_if_nil:NTF #2

   {

    prg_return_true:

   }

   {

    str_if_in:nnTF { #1 } { #2 }

     {

      __stringchecker_check:nN { #1 }

     }

     {

      __stringchecker_stop:w

     }

   }

 }

cs_new:Npn __stringchecker_stop:w #1 q_nil

 {

  prg_return_false:

 }

ExplSyntaxOff



begin{document}



checkTF{asdf}{asdfgh}{TRUE}{FALSE}



checkTF{asdf}{hgfdsa}{TRUE}{FALSE}



checkTF{asdf}{asdghj}{TRUE}{FALSE}



checkTF{}{asdghj}{TRUE}{FALSE}



checkTF{a}{}{TRUE}{FALSE}



end{document}