procedure getch;
   const tab = 9;
begin if eof then begin ch:='.'; theword:='<eof>     ' end
      else if eoln then
      begin readln; writeln; ch:=' ';
            lineno:=lineno+1; write(lineno:3, ': ')
      end
      else begin read(ch); write(ch);
                 if ord(ch)=tab then ch:=' '
           end
end{getch};

procedure insymbol;
   const blank='          ';
   var len:integer;
begin repeat while ch=' ' do getch;
             if ch='{' then  { comment }
             begin repeat getch
                   until (ch='}') or eof;
                   getch
             end
      until not( ch in [' ', '{'] );
      if eof then sy:=eofsy
      
      else if ch in ['a'..'z', 'A'..'Z'] then                             {xyz}
      begin theword:=blank;
            len:=0;
            while ch in ['a'..'z', 'A'..'Z', '0'..'9'] do
            begin len:=len+1;
                  if len<=10 then theword[len] := ch;
                  getch
            end; {not ch in ['a'..'z', '0'..'9']}
            if theword='and       ' then sy:=andsy
            else if theword='not       ' then sy:=notsy
            else if theword[1] in ['a'..'z'] then sy:=LCword
            else sy:=UCword
      end{alphanums}
      
      else if ch in ['0'..'9'] then                            {123}
      begin theint:=0;
            while ch in ['0'..'9'] do
            begin theint:=theint*10+ord(ch)-ord('0'); getch
            end;
            sy:=numeral
      end
      
      else if ch in  [ '?', '.', ',', ':', '<', '&', '(', ')', '[', ']' ] then
         case ch of
            '<': begin getch;
                       if ch='=' then begin getch; sy:=impliedby end
                       else error('not <=    ')
                 end;
            ':': begin getch;
                       if ch='-' then begin getch; sy:=impliedby end
                       else sy:=colon
                 end;
            '?', '.', ',', '(', ')', '[', ']', '&':
                 begin case ch of
                       '?': sy:=question;
                       '.': sy:=dot;    ',': sy:=comma;
                       '(': sy:=open;   ')': sy:=close;
                       '[': sy:=sqopen; ']': sy:=sqclose;
                       '&': sy:=andsy
                       end{case};
                       getch
                 end
         end{case}

      else error('bad symbol')
end{insymbol};

{\fB Lexical Analysis. \fP}