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Need to catch incorrect syntax in <formularesponse>, so students do not get
charged a try.

    1: # The LearningOnline Network with CAPA
    2: # Interface routines to MAXIMA CAS
    3: #
    4: # $Id: lonmaxima.pm,v 1.22 2008/06/10 13:31:38 www Exp $
    5: #
    6: # Copyright Michigan State University Board of Trustees
    7: #
    8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
    9: #
   10: # LON-CAPA is free software; you can redistribute it and/or modify
   11: # it under the terms of the GNU General Public License as published by
   12: # the Free Software Foundation; either version 2 of the License, or
   13: # (at your option) any later version.
   14: #
   15: # LON-CAPA is distributed in the hope that it will be useful,
   16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
   17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   18: # GNU General Public License for more details.
   19: #
   20: # You should have received a copy of the GNU General Public License
   21: # along with LON-CAPA; if not, write to the Free Software
   22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   23: #
   24: # /home/httpd/html/adm/gpl.txt
   25: #
   26: # http://www.lon-capa.org/
   27: #
   28:  
   29: package Apache::lonmaxima;
   30:  
   31: use strict;
   32: use IO::Socket;
   33: use Apache::lonnet;
   34: use Apache::response();
   35: use LONCAPA;
   36: 
   37: sub connect {
   38:    return IO::Socket::UNIX->new(Peer    => $Apache::lonnet::perlvar{'lonSockDir'}.'/maximasock',
   39: 				Type    => SOCK_STREAM,
   40: 				Timeout => 10);
   41: }
   42: 
   43: sub disconnect {
   44:     my ($socket)=@_;
   45:     if ($socket) { close($socket); }
   46: }
   47: 
   48: sub maximareply {
   49:     my ($socket,$cmd)=@_;
   50:     if ($socket) {
   51: 	print $socket &escape($cmd)."\n";
   52:         my $reply=<$socket>;
   53:         chomp($reply);
   54:         if ($reply=~/^Incorrect/) { $reply='Error: '.$reply; }
   55:         return &unescape($reply);
   56:     } else {
   57:         return 'Error: no connection.';
   58:     }
   59: }
   60: 
   61: sub blacklisted {
   62:     my ($cmd)=@_;
   63:     foreach my $forbidden ('save','load','plot','lisp','includ','compil',
   64: 			   'file','batch','stringout','translat','stout',
   65: 			   'stin','block','system','concat','read','inchar',
   66: 			   'outchar','ttyoff','with_stdout','writefile',
   67: 			   'reset') {
   68: 	if ($cmd=~/$forbidden/s) { return 1; }
   69:     } 
   70:     return 0;
   71: }
   72: 
   73: sub runscript {
   74:     my ($socket,$fullscript)=@_;
   75:     if (&blacklisted($fullscript)) { return 'Error: blacklisted'; }
   76:     my $reply;
   77:     $fullscript=~s/[\n\r\l]//gs;
   78:     foreach my $line (split(/\;/s,$fullscript)) {
   79: 	if ($line=~/\w/) { $reply=&maximareply($socket,$line.";\n"); }
   80: 	if ($reply=~/^Error\:/) { return $reply; }
   81:     }
   82:     $reply=~s/^\s*//gs;
   83:     $reply=~s/\s*$//gs;
   84:     &Apache::lonxml::debug("maxima $fullscript \n reply $reply");
   85:     return $reply;
   86: }
   87: 
   88: sub maxima_cas_formula_fix {
   89:    my ($expression)=@_;
   90:    return &Apache::response::implicit_multiplication($expression);
   91: }
   92: 
   93: sub maxima_run {
   94:     my ($script,$submission,$argument) = @_;
   95:     my $socket=&connect();
   96:     my @submissionarray=split(/\s*\,\s*/,$submission);
   97:     for (my $i=0;$i<=$#submissionarray;$i++) {
   98:         my $n=$i+1;
   99:         my $fixedsubmission=&maxima_cas_formula_fix($submissionarray[$i]);
  100:         $script=~s/RESPONSE\[$n\]/$fixedsubmission/gs;
  101:     }
  102:     my @argumentarray=@{$argument};
  103:     for (my $i=0;$i<=$#argumentarray;$i++) {
  104:         my $n=$i+1;
  105:         my $fixedargument=&maxima_cas_formula_fix($argumentarray[$i]);
  106:         $script=~s/LONCAPALIST\[$n\]/$fixedargument/gs;
  107:     }
  108:     my $reply=&runscript($socket,$script);
  109:     &disconnect($socket);
  110:     if ($reply=~/^\s*true\s*$/i) { return 'EXACT_ANS'; }
  111:     if ($reply=~/^\s*false\s*$/i) { return 'INCORRECT'; } 
  112:     return 'BAD_FORMULA';
  113: }
  114: 
  115: sub maxima_eval {
  116:     my ($script) = @_;
  117:     my $socket=&connect();
  118:     my $reply=&runscript($socket,$script);
  119:     &disconnect($socket);
  120:     return $reply;
  121: }
  122: 
  123: 
  124: sub compareterms {
  125:     my ($socket,$terma,$termb)=@_;
  126:     my $difference=$terma.'-('.$termb.')';
  127:     if (&blacklisted($difference)) { return 'Error: blacklisted'; }
  128:     my $reply=&maximareply($socket,'trigsimp(trigreduce('.$difference.'));');
  129:     if ($reply=~/^\s*0\s*$/) { return 'true'; }
  130:     if ($reply=~/^Error\:/) { return $reply; }
  131:     return 'false';
  132: }
  133: 
  134: sub maxima_check {
  135:     my ($response,$answer,$reterror) = @_;
  136:     my $socket=&connect();
  137:     my $reply=&compareterms($socket,$response,$answer);
  138:     &disconnect($socket);
  139:     # integer to string mappings come from capaParser.h
  140:     # 1 maps to 'EXACT_ANS'
  141:     if ($reply eq 'true') { return 1; }
  142:     # 11 maps to 'BAD_FORMULA'
  143:     if ($reply=~/^Error\:/) { return 11; }
  144:     # 7 maps to 'INCORRECT'
  145:     return 7;
  146: }
  147:  
  148: 1;
  149: __END__;