Rework the persistence hash and add new scaffold preview option.

lib/PGcore.pm

@@ -75,18 +75,17 @@ sub new {
 
 		# Holds other data, besides answers, which persists during a session and beyond.
 		PERSISTENCE_HASH            => $envir->{PERSISTENCE_HASH} // {},    # Main data, received from DB
-		PERSISTENCE_HASH_UPDATED    => {},                      # Keys whose updated values should be saved by the DB
 		answer_name_count           => 0,
 		implicit_named_answer_stack => [],
 		implicit_answer_eval_stack  => [],
 		explicit_answer_name_evals  => {},
 		KEPT_EXTRA_ANSWERS          => [],
 		ANSWER_PREFIX               => 'AnSwEr',
 		ARRAY_PREFIX                => 'ArRaY',
-		vec_num                     => 0,                       # for distinguishing matrices
+		vec_num                     => 0,                                   # for distinguishing matrices
 		QUIZ_PREFIX                 => $envir->{QUIZ_PREFIX},
 		PG_VERSION                  => $ENV{PG_VERSION},
-		PG_ACTIVE                   => 1,                       # toggle to zero to stop processing
+		PG_ACTIVE                   => 1,                                   # toggle to zero to stop processing
 		submittedAnswers            => 0,        # have any answers been submitted? is this the first time this session?
 		PG_session_persistence_hash => {},       # stores data from one invoction of the session to the next.
 		PG_original_problem_seed    => 0,
@@ -477,25 +476,20 @@ sub extend_ans_group {    # modifies the group type
 	return $label;
 }
 
-sub store_persistent_data {    # will store strings only (so far)
-	my ($self, $label, @values) = @_;
-	if (defined($self->{PERSISTENCE_HASH}->{$label})) {
-		warn "can' overwrite $label in persistent data";
-	} else {
-		$self->{PERSISTENCE_HASH_UPDATED}{$label} = 1;
-		$self->{PERSISTENCE_HASH}{$label}         = join("", @values);
+# Save to or retrieve data from the persistence hash.  The $label parameter is the key in the persistence hash.  If the
+# $value parameter is not given then the value of the $label key in the hash will be returned.  If the $value parameter
+# is given then the value of the $label key in the hash will be saved or updated.  Note that if the $value parameter is
+# given but is undefined then the $label key will be deleted from the hash.  Anything that can be JSON encoded can be
+# stored.
+sub persistent_data {
+	my ($self, $label, $value) = @_;
+	if (@_ > 2) {
+		if (defined $value) {
+			$self->{PERSISTENCE_HASH}{$label} = $value;
+		} else {
+			delete $self->{PERSISTENCE_HASH}{$label};
+		}
 	}
-	$label;
-}
-
-sub update_persistent_data {    # will store strings only (so far)
-	my ($self, $label, @values) = @_;
-	$self->{PERSISTENCE_HASH_UPDATED}{$label} = 1;
-	$self->{PERSISTENCE_HASH}{$label}         = join("", @values);
-}
-
-sub get_persistent_data {
-	my ($self, $label) = @_;
 	return $self->{PERSISTENCE_HASH}{$label};
 }
 

lib/WeBWorK/PG.pm

@@ -264,10 +264,6 @@ sub defineProblemEnvironment ($pg_envir, $options = {}, $image_generator = undef
 		showMessages            => $options->{showMessages}            // 1,
 		showCorrectAnswers      => $options->{showCorrectAnswers}      // 0,
 
-		# The next has marks what data was updated and needs to be saved
-		# by the front end.
-		PERSISTENCE_HASH_UPDATED => {},
-
 		inputs_ref => $options->{inputs_ref},
 
 		(map { $_ => $ansEvalDefaults->{$_} } keys %$ansEvalDefaults),

macros/PG.pl

@@ -545,19 +545,47 @@ sub ANS_NUM_TO_NAME {
 	$PG->new_label(@_);
 }
 
+=head2 persistent_data
+
+Save to or retrieve data from the persistence hash. The persistence hash is data
+that will persist for this problem.  It is saved when answers are submitted, and
+can be retrieved and used within a problem.
+
+    persistent_data($label);
+    persistent_data($label, $value);
+
+The C<$label> parameter is the key in the persistence hash.  If the C<$value>
+parameter is not given then the value of the C<$label> key in the hash will be
+returned.  If the C<$value> parameter is given then the value of the C<$label>
+key in the hash will be saved or updated.  Note that if the C<$value> parameter
+is given but is undefined then the C<$label> key will be deleted from the hash.
+Anything that can be JSON encoded can be stored.
+
+=cut
+
+sub persistent_data {
+	my ($label, @value) = @_;
+	return $PG->persistent_data($label, @value);
+}
+
+# The store_persistent_data, update_persistent_data, and get_persistent_data methods are deprecated and are only still
+# here for backward compatability. Use the persistent_data method instead which can do everything these three methods
+# can do. Note that if you use the persistent_data method, then you will need to join the values as strings if you want
+# that. Even better pass the persistent_data method an array reference containing the values so you can avoid the hassle
+# of splitting the values when they are retrieved.
 sub store_persistent_data {
 	my ($label, @values) = @_;
-	$PG->store_persistent_data($label, @values);
+	return $PG->persistent_data($label, join('', @values));
 }
 
 sub update_persistent_data {
 	my ($label, @values) = @_;
-	$PG->update_persistent_data($label, @values);
+	return $PG->persistent_data($label, join('', @values));
 }
 
 sub get_persistent_data {
 	my ($label) = @_;
-	return $PG->get_persistent_data($label);
+	return $PG->persistent_data($label);
 }
 
 sub add_content_post_processor {

macros/core/scaffold.pl

@@ -184,6 +184,16 @@ =head1 DESCRIPTION
 have the student open it by hand before anwering the questions.  In
 this case, set this value to 0 (it is 1 by default).
 
+=item C<S<< preview_can_change_state => 0 or 1 >>
+
+This determines if scaffold state can be changed when a preview occurs
+(i.e., when the "Preview My Answers" button is used).  If this is 0,
+then when a preview occurs any scaffold sections that were open before
+the preview will remain open, and any scaffold sections that were closed
+before the preview will remain closed. If this is 1, then the rules
+described above will be applied using the scores of the answers in the
+parts.  This is 1 by default.
+
 =item C<S<< numbered => 0 or 1 >>>
 
 This determines whether each section is automatically numbered before
@@ -353,6 +363,7 @@ sub new {
 		hardcopy_is_open          => "always",                  # open all possible sections in hardcopy
 		open_first_section        => 1,                         # 0 means don't open any sections initially
 		numbered                  => 0,                         # 1 means sections will be printed with their number
+		preview_can_change_state  => 1,
 		%options,
 		number     => ++$scaffold_no,                           # the number for this scaffold
 		depth      => $scaffold_depth,                          # the nesting depth for this scaffold
@@ -536,16 +547,24 @@ sub add_container {
 		# Nothing needs to be done for the PTX display mode.
 		return if $Scaffold::isPTX;
 
+		my $scaffoldScores = main::persistent_data('_scaffold_scores') // {};
+
 		# Provide a "scaffold_force" option in the AnswerHash that can be used to force
 		# Scaffold to consider the score to be 1. This is used by PGessaymacros.pl.
+		# Also, if answers are being previewed and the preview_can_change_state option is 0, then use the scores saved
+		# in the persistent data hash form the last answer submission (if there is no data for an answer, then the
+		# anwser is considered blank).
 		for (@{ $self->{ans_names} }) {
 			next unless defined $PG_ANSWERS_HASH->{$_};
-			$scaffold->{scores}{$_} =
-				$PG_ANSWERS_HASH->{$_}{ans_eval}{rh_ans}{scaffold_force}
-				? 1
+			$scaffold->{scores}{$_} = $scaffoldScores->{$_} =
+				$PG_ANSWERS_HASH->{$_}{ans_eval}{rh_ans}{scaffold_force} ? 1
+				: !$scaffold->{preview_can_change_state} && $PG_ANSWERS_HASH->{$_}{ans_eval}{rh_ans}{isPreview}
+				? $scaffoldScores->{$_}
 				: $PG_ANSWERS_HASH->{$_}{ans_eval}{rh_ans}{score};
 		}
 
+		main::persistent_data(_scaffold_scores => $scaffoldScores);
+
 		# Set the active scaffold to the scaffold for this section so that is_correct, can_open,
 		# and is_open methods use the correct one.
 		$Scaffold::scaffold = $scaffold;