!This file is part of VEL_demo, copyright David Keyes, 2007. 
    !
    !This source file is free software: you can redistribute it and/or modify
    !it under the terms of the GNU General Public License as published by
    !the Free Software Foundation, either version 3 of the License, or
    !(at your option) any later version.
    !
    !This code is distributed in the hope that it will be useful,
    !but WITHOUT ANY WARRANTY; without even the implied warranty of
    !MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    !GNU General Public License for more details.
    !
    !For terms of the GNU General Public license see <http://www.gnu.org/licenses/>.

GLOBAL MODULE evaluate(
STRING input*132; ! input string only contains numbers and a maximum of one operator !
VAR FLOAT rtn_flt);

INT n, stat;
FLOAT tmp, ft;
STRING left*132, right*132;

BEGINMODULE

  ! search for operators !
ft:=0;
stat:=0;
  n:=finds(input, "+");
  IF n <> 0 THEN
    part(#1, split_str(input, "+", left, right));
    rtn_flt:=fval(left) + fval(right);
    stat:=1;
  ENDIF;

  n:=finds(input, "*");
  IF n <> 0 THEN
    part(#2, split_str(input, "*", left, right));
    rtn_flt:=fval(left) *  fval(right);
    stat:=1;
  ENDIF;

IF stat=0 THEN
  n:=finds(input, " ");
  IF n <> 0 THEN
  ! have to split it again, intended for items like "1 1/4" !
  !  that  we want to read as 1.25 !

    part(#3, split_str(input, " ", left, right));
    tmp:=fval(left);
    part(#4, split_str(right, "/", left, right));
    rtn_flt:=tmp + (fval(left) / fval(right));
    stat:=1;
  ENDIF;
ENDIF;
  n:=finds(input, "'");
  IF n <> 0 THEN
    part(#5, split_str(input, "'", left, right));
    ft:=fval(left)*12;
! strip the potential minus sign !
    IF substr(right,1,1) = "-" THEN
	input:=substr(right,2);
    ELSE 
	input:=right;
    ENDIF; 
    stat:=2;
  ENDIF;

  IF stat = 2 THEN
	  n:=finds(input, " ");
	  IF n <> 0 THEN
	    part(#6, split_str(input, " ", left, right));
	    tmp:=fval(left);
	    part(#7, split_str(right, "/", left, right));
	    rtn_flt:=ft+tmp + (fval(left) / fval(right));
	    stat:=1;
	  ELSE
	    rtn_flt:=ft +(fval(left));
	  ENDIF;

  ELIF stat = 0 THEN
	  n:=finds(input, "-");
	  IF n <> 0 THEN
	    part(#16, split_str(input, "-", left, right));
	    rtn_flt:=fval(left) - fval(right);
	    stat:=1;
	  ENDIF;

	  n:=finds(input, "/");
	  IF n <> 0 THEN
	    part(#17, split_str(input, "/", left, right));
	    rtn_flt:=fval(left) / fval(right);
	    stat:=1;
	  ENDIF;
  ENDIF;


IF stat = 0 THEN
    rtn_flt:=fval(input);
ENDIF;

ENDMODULE