--- loncom/homework/default_homework.lcpm	2004/03/16 15:31:52	1.73
+++ loncom/homework/default_homework.lcpm	2004/03/19 22:02:03	1.75
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA 
 # used by lonxml::xmlparse() as input variable $safeinit to Apache::run::run()
 #
-# $Id: default_homework.lcpm,v 1.73 2004/03/16 15:31:52 albertel Exp $
+# $Id: default_homework.lcpm,v 1.75 2004/03/19 22:02:03 albertel Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -40,16 +40,20 @@ $deg2rad=$pi/180.0;
 $"=' ';
 
 sub caparesponse_check {
+    my ($answer,$response)=@_;
     #not properly used yet: calc
     #not to be used: $ans_fmt
-    my ($type,$tol,$sig,$ans_fmt,$unit,$calc,$samples) =
-	eval $_[2].
-	';return ($__LC__type,$__LC__tol,$__LC__sig,$__LC__ans_fmt,$__LC__unit,$__LC__calc,$__LC__samples);';
+    my $type=$LONCAPA::CAPAresponse_args{'type'};
+    my $tol=$LONCAPA::CAPAresponse_args{'tol'};
+    my $sig=$LONCAPA::CAPAresponse_args{'sig'};
+    my $ans_fmt=$LONCAPA::CAPAresponse_args{'ans_fmt'};
+    my $unit=$LONCAPA::CAPAresponse_args{'unit'};
+    my $calc=$LONCAPA::CAPAresponse_args{'calc'};
+    my $samples=$LONCAPA::CAPAresponse_args{'samples'};
     
     my $tol_type=''; # gets it's value from whether tol has a % or not done
     my $sig_lbound=''; #done
     my $sig_ubound=''; #done
-    my ($answer,$response,$expr)=@_;
 
 
     #type's definitons come from capaParser.h
@@ -68,7 +72,7 @@ sub caparesponse_check {
     if (length($response) > 500) { return "TOO_LONG: Answer too long"; }
 
     if ($type eq '' ) {
-	$message .= "Didn't find a type :$type:$expr: defaulting\n";
+	$message .= "Didn't find a type :$type: defaulting\n";
 	if ( $answer eq ($answer *1.0)) { $type = 2;
 				      } else { $type = 3; }
     } else {
@@ -134,20 +138,21 @@ sub caparesponse_check {
     elsif ($result =='12') { $result='WANTED_NUMERIC'; }
     else  {$result = "ERROR: Unknown Result:$result:$@:";}
 
-    return ("$result:\nRetError $reterror:\nError $error:\nAnswer $answer:\nResponse $response:\n type-$type|$tol|$tol_type|$sig:$sig_lbound:$sig_ubound|$unit|\n$message$expr",$reterror);
+    return ("$result:\nRetError $reterror:\nError $error:\nAnswer $answer:\nResponse $response:\n type-$type|$tol|$tol_type|$sig:$sig_lbound:$sig_ubound|$unit|\n$message",$reterror);
 }
 
 
 sub caparesponse_check_list {
-    my ($response,$expr)=@_;
+    my $response=$LONCAPA::CAPAresponse_args{'response'};
     my ($result,@list);
-    @list=@CAPARESPONSE_CHECK_LIST_answer;
+    @list=@LONCAPA::CAPAresponse_answer;
     my $aresult='';
     my $current_answer;
     my $answers=join(':',@list);
     $result.="Got response :$answers:\n";
+    &LONCAPA_INTERNAL_DEBUG("<blink>Yo!</blink> got ".join(':',%LONCAPA::CAPAresponse_args));
     my @responselist;
-    my $type =eval $expr.';return $__LC__type;';
+    my $type = $LONCAPA::CAPAresponse_args{'type'};
     $result.="Got type :$type:\n";
     if ($type ne '' && $#list > 0) {
 	(@responselist)=split /,/,$response;
@@ -175,12 +180,10 @@ sub caparesponse_check_list {
 	my $thisanswer=$list[$i];
 	$result.="trying answer :$thisanswer:\n";
 	if ($unit eq '') {
-	    ($aresult,$msg)=&caparesponse_check($thisanswer,$responselist[$i],
-						$expr);
+	    ($aresult,$msg)=&caparesponse_check($thisanswer,$responselist[$i]);
 	} else {
 	    ($aresult,$msg)=&caparesponse_check($thisanswer,
-						$responselist[$i]." $unit",
-						$expr);
+						$responselist[$i]." $unit");
 	}
 	my ($temp)=split /:/, $aresult;
 	$awards.="$temp,";
@@ -482,11 +485,51 @@ sub format {
     return $result;
 }
 
+sub chemparse {
+    my ($reaction) = @_;
+    my @tokens = split(/(\s\+|\->|<=>)/,$reaction);
+    my $formula = '';
+    foreach my $token (@tokens) {
+	if ($token eq '->' ) {
+	    $formula .= '<m>\ensuremath{\rightarrow}</m> ';
+	    next;
+	}
+	if ($token eq '<=>') {
+	    if ($external::target eq 'web' &&
+		&EXT('request.browser.unicode')) {
+		$formula .= '&#8660; ';
+	    } else {
+		$formula .= &web('<=> ','<m>\ensuremath{\rightleftharpoons}</m> ',
+				 '&lt;=$gt; ');
+	    }
+	    next;
+	}
+	$token =~ /^\s*(\d*)(.*)/;
+	$formula .= $1 if ($1 > 1);  # stoichiometric coefficient
+	
+	my $molecule = $2;
+	# subscripts
+	$molecule =~ s|(?<=[a-zA-Z\[\s])(\d+)|<sub>$1</sub>|g;
+	# superscripts
+	$molecule =~ s|\^(\d*[+\-]*)|<sup>$1</sup>|g;
+	# strip whitespace
+	$molecule =~ s/\s*//g;
+	# forced space
+	$molecule =~ s/_/ /g;
+	$formula .= $molecule.'&nbsp;';
+    }
+    # get rid of trailing space
+    $formula =~ s/(\Q${nbsp}\E| )$//;
+    
+    return &xmlparse($formula);
+}
+
 sub prettyprint {
     my ($value,$fmt,$target)=@_;
     my $result;
     my $dollarmode;
     if (!$target) { $target = $external::target; }
+    if ($fmt =~ /chem/i) { return(&chemparse($value)); }
     if ($fmt =~ /^\$(.*)/) { $fmt=$1; $dollarmode=1; } 
     if ($fmt) { $value=sprintf('%.'.$fmt,$value); }
     if ($value =~ /([0-9\.\-\+]+)E([0-9\-\+]+)/i ) {