[WWcvs] webwork2: Added support for the tthPreamble.tex file.

[Sam H. v. a. <we...@ma...>]

Log Message:
-----------
Added support for the tthPreamble.tex file. The effect of this code is 
the same as the corresponding code in dangerousMacros.pl:tth(), but the 
technique is slightly different.

This is a hack. Eventually, we'd like to have a common out-of-sandbox 
method of calling TTH.

Closes bug #799.

Modified Files:
--------------
    webwork2/lib/WeBWorK/ContentGenerator:
        Problem.pm

Revision Data
-------------
Index: Problem.pm
===================================================================
RCS file: /webwork/cvs/system/webwork2/lib/WeBWorK/ContentGenerator/Problem.pm,v
retrieving revision 1.172
retrieving revision 1.173
diff -Llib/WeBWorK/ContentGenerator/Problem.pm -Llib/WeBWorK/ContentGenerator/Problem.pm -u -r1.172 -r1.173
--- lib/WeBWorK/ContentGenerator/Problem.pm
+++ lib/WeBWorK/ContentGenerator/Problem.pm
@@ -31,7 +31,7 @@
 use WeBWorK::PG;
 use WeBWorK::PG::ImageGenerator;
 use WeBWorK::PG::IO;
-use WeBWorK::Utils qw(writeLog writeCourseLog encodeAnswers decodeAnswers ref2string makeTempDirectory);
+use WeBWorK::Utils qw(readFile writeLog writeCourseLog encodeAnswers decodeAnswers ref2string makeTempDirectory);
 use WeBWorK::DB::Utils qw(global2user user2global findDefaults);
 use WeBWorK::Timing;
 use URI::Escape;
@@ -217,11 +217,12 @@
 	my $fully = '';
 	my @tableRows = ( $header );
 	my $numCorrect = 0;
+	my $tthPreambleCache;
 	foreach my $name (@answerNames) {
 		my $answerResult  = $pg->{answers}->{$name};
 		my $studentAnswer = $answerResult->{student_ans}; # original_student_ans
 		my $preview       = ($showAttemptPreview
-		                    	? $self->previewAnswer($answerResult, $imgGen)
+		                    	? $self->previewAnswer($answerResult, $imgGen, \$tthPreambleCache)
 		                    	: "");
 		my $correctAnswer = $answerResult->{correct_ans};
 		my $answerScore   = $answerResult->{score};
@@ -277,7 +278,7 @@
 
 
 sub previewAnswer {
-	my ($self, $answerResult, $imgGen) = @_;
+	my ($self, $answerResult, $imgGen, $tthPreambleCache) = @_;
 	my $ce            = $self->r->ce;
 	my $effectiveUser = $self->{effectiveUser};
 	my $set           = $self->{set};
@@ -296,9 +297,30 @@
 	if ($displayMode eq "plainText") {
 		return $tex;
 	} elsif ($displayMode eq "formattedText") {
+		
+		# read the TTH preamble, or use the cached copy passed in from the caller
+		my $tthPreamble;
+		if (defined $$tthPreambleCache) {
+			$tthPreamble = $$tthPreambleCache;
+		} else {
+			my $tthPreambleFile = $ce->{courseDirs}->{templates} . "/tthPreamble.tex";
+			if (-r $tthPreambleFile) {
+				$tthPreamble = readFile($tthPreambleFile);
+				# thanks to Jim Martino. each line in the definition file should end with
+				#a % to prevent adding supurious paragraphs to output:
+				$tthPreamble =~ s/(.)\n/$1%\n/g;
+				# solves the problem if the file doesn't end with a return:
+				$tthPreamble .="%\n";
+				# store preamble in cache:
+				$$tthPreambleCache = $tthPreamble;
+			} else {
+			}
+		}
+		
+		# construct TTH command line
 		my $tthCommand = $ce->{externalPrograms}->{tth}
 			. " -L -f5 -r 2> /dev/null <<END_OF_INPUT; echo > /dev/null\n"
-			. "\\(".$tex."\\)\n"
+			. $tthPreamble . "\\(" . $tex . "\\)\n"
 			. "END_OF_INPUT\n";
 		
 		# call tth
@@ -308,6 +330,7 @@
 		} else {
 			return $result;
 		}
+		
 	} elsif ($displayMode eq "images") {
 		$imgGen->add($tex);
 	} elsif ($displayMode eq "jsMath") {