Parsons filter to extract final submission only

stack/cas/parsingrules/909_parsons_decode_state_for_display.filter.php → stack/cas/parsingrules/908_parsons_decode_state_for_display.filter.php

@@ -26,7 +26,7 @@
 require_once(__DIR__ . '/../../utils.class.php');
 
 // phpcs:ignore moodle.Commenting.MissingDocblock.Class
-class stack_ast_filter_909_parsons_decode_state_for_display implements stack_cas_astfilter {
+class stack_ast_filter_908_parsons_decode_state_for_display implements stack_cas_astfilter {
     // phpcs:ignore moodle.Commenting.MissingDocblock.Function
     public function filter(MP_Node $ast, array &$errors, array &$answernotes, stack_cas_security $identifierrules): MP_Node {
         $strings = function($node) use (&$answernotes, &$errors) {

stack/cas/parsingrules/909_parsons_get_final_submission.filter.php

@@ -0,0 +1,47 @@
+<?php
+// This file is part of Stack - https://stack.maths.ed.ac.uk
+//
+// Stack 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.
+//
+// Stack 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.
+//
+// You should have received a copy of the GNU General Public License
+// along with Stack.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Add description here!
+ * @package    qtype_stack
+ * @copyright  2024 University of Edinburgh.
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later.
+ */
+
+defined('MOODLE_INTERNAL') || die();
+require_once(__DIR__ . '/filter.interface.php');
+require_once(__DIR__ . '/../../utils.class.php');
+
+// phpcs:ignore moodle.Commenting.MissingDocblock.Class
+class stack_ast_filter_909_parsons_get_final_submission implements stack_cas_astfilter {
+    // phpcs:ignore moodle.Commenting.MissingDocblock.Function
+    public function filter(MP_Node $ast, array &$errors, array &$answernotes, stack_cas_security $identifierrules): MP_Node {
+        $strings = function($node) use (&$answernotes, &$errors) {
+            // We validate the node to check that it is a string that represents a Parson's state.
+            // This is not strictly required as it is prevented by `$node instanceof MP_String`, but it is an additional safety
+            // measure to ensure we do not dehash other strings.
+            if ($node instanceof MP_String && stack_parsons_input::validate_parsons_string($node->value)) {
+                $decoded = json_decode($node->value);
+                $node->value = json_encode(reset($decoded));
+            }
+
+            return true;
+        };
+
+        $ast->callbackRecurse($strings);
+        return $ast;
+    }
+}

stack/cas/parsingrules/parsingrule.factory.php

@@ -72,7 +72,8 @@
 require_once(__DIR__ . '/801_singleton_numeric.filter.php');
 require_once(__DIR__ . '/802_singleton_units.filter.php');
 require_once(__DIR__ . '/901_remove_comments.filter.php');
-require_once(__DIR__ . '/909_parsons_decode_state_for_display.filter.php');
+require_once(__DIR__ . '/908_parsons_decode_state_for_display.filter.php');
+require_once(__DIR__ . '/909_parsons_get_final_submission.filter.php');
 require_once(__DIR__ . '/910_inert_float_for_display.filter.php');
 require_once(__DIR__ . '/912_inert_string_for_display.filter.php');
 require_once(__DIR__ . '/990_no_fixing_spaces.filter.php');
@@ -190,8 +191,10 @@ private static function build_from_name(string $name): stack_cas_astfilter {
                 return new stack_ast_filter_802_singleton_units();
             case '901_remove_comments':
                 return new stack_ast_filter_901_remove_comments();
-            case '909_parsons_decode_state_for_display' :
-                return new stack_ast_filter_909_parsons_decode_state_for_display();
+            case '908_parsons_decode_state_for_display' :
+                return new stack_ast_filter_908_parsons_decode_state_for_display();
+            case '909_parsons_get_final_submission':
+                return new stack_ast_filter_909_parsons_get_final_submission();
             case '910_inert_float_for_display':
                 return new stack_ast_filter_910_inert_float_for_display();
             case '912_inert_string_for_display':
@@ -251,8 +254,10 @@ public static function get_by_common_name(string $name): stack_cas_astfilter {
                 '601_castext', '602_castext_simplifier', '680_gcl_sconcat',
                 '610_castext_static_string_extractor',
                 '650_string_protect_slash',
-                '801_singleton_numeric', '802_singleton_units', '901_remove_comments',
-                '909_parsons_decode_state_for_display',
+                '801_singleton_numeric', '802_singleton_units', 
+                '901_remove_comments',
+                '908_parsons_decode_state_for_display',
+                '909_parsons_get_final_submission',
                 '910_inert_float_for_display',
                 '912_inert_string_for_display',
                 '990_no_fixing_spaces', '991_no_fixing_stars',

stack/input/inputbase.class.php

@@ -994,6 +994,10 @@ protected function validate_contents_filters($basesecurity) {
         // Then ban the rest.
         $filterstoapply[] = '505_no_evaluation_groups';
 
+        if (get_class($this) === 'stack_parsons_input') {
+            $filterstoapply[] = '909_parsons_get_final_submission';
+        }
+
         // Remove scripts and other related things from string-values.
         $filterstoapply[] = '997_string_security';
 

stack/input/parsons/parsons.class.php

@@ -95,7 +95,7 @@ private static function answer_function_testcase($ta) {
      * Filters to apply for display in validate_contents
      * @var array
      */
-    protected $protectfilters = ['909_parsons_decode_state_for_display', '910_inert_float_for_display',
+    protected $protectfilters = ['908_parsons_decode_state_for_display', '910_inert_float_for_display',
         '912_inert_string_for_display', ];
 
     /**

stack/maxima/contrib/prooflib.mac

@@ -124,7 +124,7 @@ proof_remove_nullproof(ex):= block(
  * Take the JSON from STACK Parson's block and return a proof function.
  */
 proof_parsons_interpret(st) := block([pf],
-  pf:first(first(stackjson_parse(st))),
+  pf:first(stackjson_parse(st)),
   pf:apply(proof, first(first(stackmap_get(pf, "used"))))
 );
 

stack/maxima/proof.mac

@@ -161,7 +161,7 @@ parsons_encode(steps) := block(
  * Take the hashed JSON from STACK Parson's block and return a proof function.
  */
 parsons_decode(st) := block([pf],
-  pf:first(first(stackjson_parse(st))),
+  pf:first(stackjson_parse(st)),
   pf:ev(apply(proof, unhash_keys_list(first(first(stackmap_get(pf, "used"))))),simp)
 );
 

stack/utils.class.php

@@ -1055,7 +1055,7 @@ public static function is_array_string($str) {
      */
     public static function unhash_parsons_string($listofjsons) {
         $decodedlist = json_decode($listofjsons);
-        if (!is_array($decoded)) {
+        if (!is_array($decodedlist)) {
             return stack_string('invalid_json');;
         }
         foreach ($decodedlist as $key => $json) {
@@ -1098,7 +1098,7 @@ public static function unhash_parsons_string_maxima($listofjsons) {
      */
     public static function hash_parsons_string($listofjsons) {
         $decodedlist = json_decode($listofjsons);
-        if (!is_array($decoded)) {
+        if (!is_array($decodedlist)) {
             return stack_string('invalid_json');;
         }
         foreach ($decodedlist as $key => $json) {