Fix candidate for #824. Not ready! Currently breaks CASText simplification control.

cli/ast_filter_tester.php

@@ -173,8 +173,8 @@ if ($only === false) {
                                'letToken' => stack_string('equiv_LET')));
     }
 
-    $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array('996_call_modification', '998_security'),
-            array('998_security' => array('security' => 's')), true);
+    $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array('995_ev_modification', '996_call_modification', '998_security'),
+            array('998_security' => array('security' => 's'), '995_ev_modification' => ['flags' => false]), true);
     check_filter($freshast, $pipeline, new stack_cas_security(false), 'core + security(s)');
 
     cli_heading('= core + security(t) + strict =');
@@ -186,7 +186,7 @@ if ($only === false) {
                                'letToken' => stack_string('equiv_LET')));
     }
 
-    $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array('996_call_modification', '998_security', '999_strict'),
-            array('998_security' => array('security' => 't')), true);
+    $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array('995_ev_modification', '996_call_modification', '998_security', '999_strict'),
+            array('998_security' => array('security' => 't'), '995_ev_modification' => ['flags' => true]), true);
     check_filter($freshast, $pipeline, new stack_cas_security(false), 'core + security(t) + strict');
 }

stack/cas/ast.container.silent.class.php

@@ -200,11 +200,12 @@ class stack_ast_container_silent implements cas_evaluatable {
         }
 
         // As we take no filter options for teachers sourced stuff lets build them from scratch.
-        $filteroptions = array('998_security' => array('security' => 't'));
+        $filteroptions = array('998_security' => ['security' => 't'], '995_ev_modification' => ['flags' => true]);
 
         // Get the filter pipeline. Now we only want the core filtters and
         // append the strict syntax check to the end.
-        $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array('996_call_modification', '998_security',
+        $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array(
+            '995_ev_modification', '996_call_modification', '998_security',
             '999_strict'), $filteroptions, true);
 
         if ($ast !== null) {
@@ -232,8 +233,10 @@ class stack_ast_container_silent implements cas_evaluatable {
 
         $errors = array();
         $answernotes = array();
-        $filteroptions = array('998_security' => array('security' => 't'));
-        $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array('998_security', '999_strict'), $filteroptions, true);
+        $filteroptions = array('998_security' => ['security' => 't']);
+
+        $pipeline = stack_parsing_rule_factory::get_filter_pipeline(array('998_security',
+            '999_strict'), $filteroptions, true);
         $ast = $pipeline->filter($ast, $errors, $answernotes, $securitymodel);
 
         $astc = new static;

stack/cas/keyval.class.php

@@ -329,9 +329,11 @@ class stack_cas_keyval {
         $errors = [];
         $answernotes = [];
         $filteroptions = ['998_security' => ['security' => 't'],
-            '601_castext' => ['context' => $contextname, 'errclass' => $this->errclass]];
+            '601_castext' => ['context' => $contextname, 'errclass' => $this->errclass], 
+            '995_ev_modification' => ['flags' => true]];
         $pipeline = stack_parsing_rule_factory::get_filter_pipeline(['601_castext',
-            '602_castext_simplifier', '680_gcl_sconcat', '996_call_modification', '998_security', '999_strict'],
+            '602_castext_simplifier', '680_gcl_sconcat', '995_ev_modification',
+            '996_call_modification', '998_security', '999_strict'],
             $filteroptions, true);
         $tostringparams = ['nosemicolon' => true, 'pmchar' => 1];
         $securitymodel = $this->security;

stack/cas/parsingrules/995_ev_modification.filter.php

+<?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/>.
+
+defined('MOODLE_INTERNAL') || die();
+require_once(__DIR__ . '/filter.interface.php');
+require_once(__DIR__ . '/996_call_modification.filter.php');
+
+/**
+ * AST filter that rewrites calls to ev in such a way that they can deal
+ * with the security system. Also rewrites evaluation flags if they are 
+ * in play.
+ */
+class stack_ast_filter_995_ev_modification implements stack_cas_astfilter_parametric {
+
+    // Unique counter for temp vars.
+    public static $TMPVARCOUNT = 1;
+
+    // Whether to rewrite evaluation flags. Don't do for students.
+    private $flags = false;
+
+    public function set_filter_parameters(array $parameters) {
+        $this->flags = isset($parameters['flags']) ? $parameters['flags'] : false;
+    }
+
+    public function filter(MP_Node $ast, array &$errors, array &$answernotes, stack_cas_security $identifierrules): MP_Node {
+
+        $process = function($node) {
+            if ($this->flags && $node instanceof MP_Statement && 
+                $node->flags !== null && count($node->flags) > 0) {
+                $fun = new MP_FunctionCall(new MP_Identifier('ev'), [$node->statement]);
+                if ($node->statement instanceof MP_Operation && $node->statement->op === ':') {
+                    $fun->arguments[0] = $node->statement->rhs;
+                    $node->statement->rhs = $fun;
+                }
+                foreach ($node->flags as $flag) {
+                    $fun->arguments[] = new MP_Operation('=', $flag->name, $flag->value);
+                }
+                $node->flags = [];
+                return false;
+            }
+            if ($node instanceof MP_FunctionCall && $node->name instanceof MP_Atom &&
+                $node->name->value === 'ev') {
+                $payload = $node->arguments[0];
+                $tc = $payload->type_count();
+                // Do not touch these, indempotent behaviour required.
+                if (isset($tc['funs'][stack_ast_filter_996_call_modification::EXPCHECK])) {
+                    unset($tc['funs'][stack_ast_filter_996_call_modification::EXPCHECK]);
+                }
+                if (count($tc['funs']) > 0) {
+                    // Complex `ev`. As in iss824.
+                    $id = '%_ev_tmp_' . self::$TMPVARCOUNT;
+                    self::$TMPVARCOUNT = self::$TMPVARCOUNT + 1;
+                    $id2 = '%_ev_tmp_' . self::$TMPVARCOUNT;
+                    self::$TMPVARCOUNT = self::$TMPVARCOUNT + 1;
+                    $replacement = new MP_Group([new MP_Operation(':', new MP_Identifier($id2), new MP_Identifier('simp')), new MP_Operation(':', new MP_Identifier('simp'), new MP_Boolean(false)), new MP_Operation(':', new MP_Identifier($id), $payload), new MP_Operation(':', new MP_Identifier('simp'), new MP_Identifier($id2)), $node]);
+                    $node->arguments[0] = new MP_Identifier($id);
+                    $node->parentnode->replace($node, $replacement);
+                    return false;
+                }
+            }
+            return true;
+        };
+
+        // @codingStandardsIgnoreStart
+        while (!$ast->callbackRecurse($process)) { }
+        // @codingStandardsIgnoreEnd
+
+        return $ast;
+    }
+}

stack/cas/parsingrules/parsingrule.factory.php

@@ -62,6 +62,7 @@ require_once(__DIR__ . '/802_singleton_units.filter.php');
 require_once(__DIR__ . '/910_inert_float_for_display.filter.php');
 require_once(__DIR__ . '/990_no_fixing_spaces.filter.php');
 require_once(__DIR__ . '/991_no_fixing_stars.filter.php');
+require_once(__DIR__ . '/995_ev_modification.filter.php');
 require_once(__DIR__ . '/996_call_modification.filter.php');
 require_once(__DIR__ . '/997_string_security.filter.php');
 require_once(__DIR__ . '/998_security.filter.php');
@@ -166,6 +167,8 @@ class stack_parsing_rule_factory {
                 return new stack_ast_filter_990_no_fixing_spaces();
             case '991_no_fixing_stars':
                 return new stack_ast_filter_991_no_fixing_stars();
+            case '995_ev_modification':
+                return new stack_ast_filter_995_ev_modification();
             case '996_call_modification':
                 return new stack_ast_filter_996_call_modification();
             case '997_string_security':
@@ -211,7 +214,7 @@ class stack_parsing_rule_factory {
                            '801_singleton_numeric', '802_singleton_units',
                            '910_inert_float_for_display',
                            '990_no_fixing_spaces', '991_no_fixing_stars',
-                           '996_call_modification',
+                           '995_ev_modification', '996_call_modification',
                            '997_string_security',
                            '998_security', '999_strict') as $name) {
                 self::$singletons[$name] = self::build_from_name($name);

tests/maxima_replication_test.php

+<?php
+// This file is part of Stack - http://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/>.
+
+namespace qtype_stack;
+
+use qtype_stack_testcase;
+use stack_ast_container;
+use stack_cas_keyval;
+use stack_cas_security;
+use stack_cas_session2;
+use castext2_evaluatable;
+use stack_secure_loader;
+
+defined('MOODLE_INTERNAL') || die();
+
+require_once(__DIR__ . '/../locallib.php');
+require_once(__DIR__ . '/fixtures/test_base.php');
+require_once(__DIR__ . '/../stack/cas/cassession2.class.php');
+require_once(__DIR__ . '/../stack/cas/keyval.class.php');
+require_once(__DIR__ . '/../stack/cas/secure_loader.class.php');
+require_once(__DIR__ . '/../stack/cas/castext2/castext2_evaluatable.class.php');
+
+/**
+ * Tests confirming that what happens in raw maxima will also happen in STACK
+ * when STACK does its own security and other rewriting.
+ * 
+ * @group qtype_stack
+ * @covers \stack_cas_keyval
+ */
+class maxima_replication_test extends qtype_stack_testcase {
+
+    /**
+     * All tests in this set of tests share the form of having
+     * a section of code which will be taken as a keyval and which
+     * contains a variable named `RESULT` that will end up containing
+     * something that will be compared to the expected form. The result
+     * will be outputted as `string(RESULT)`. In this case, we do that
+     * outputting through a CASText-evaluatable.
+     */
+    public function check($code, $result) {
+        // Do a full compile of the keyval.
+        $keyval = new stack_cas_keyval($code, null, 123);
+        $keyval->get_valid();
+        $keyval = new stack_secure_loader($keyval->compile('test')['statement']);
+        $output = castext2_evaluatable::make_from_source('{#RESULT#}', 'test');
+        $output->get_valid();
+        $session = new stack_cas_session2([$keyval, $output], null, 123);
+
+        // Execute.
+        $session->instantiate();
+
+        $this->assertEquals($result, $output->get_rendered());
+    }
+
+    public function test_matrix_mult() {
+        $code = 'simp:true;';
+        $code .= 'a:matrix([1,2],[3,4]);';
+        $code .= 'RESULT:a.a;';
+
+        $result = 'matrix([7,10],[15,22])';
+
+        $this->check($code, $result);
+    }
+
+
+    public function test_ev_flag_1() {
+        $code = 'simp:true;';
+        $code .= 'a:1+t;';
+        $code .= 'RESULT:a,t=1;';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_ev_flag_2() {
+        $code = 'simp:true;';
+        $code .= 'a:sqrt(t);';
+        $code .= 'RESULT:a,t=4;';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_ev_flag_3() {
+        $code = 'simp:false;';
+        $code .= 'a:1+1;';
+        $code .= 'RESULT:a;';
+
+        $result = '1+1';
+
+        $this->check($code, $result);
+
+        $code = 'simp:false;';
+        $code .= 'a:1+1,simp;';
+        $code .= 'RESULT:a;';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_ev_flag_4() {
+        $code = 'simp:true;';
+        $code .= 'foo(x):=0+sqrt(x);';
+        $code .= 'RESULT:foo(t),t=4;';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_ev_1() {
+        $code = 'simp:true;';
+        $code .= 'a:1+t;';
+        $code .= 'RESULT:ev(a,t=1);';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_ev_2() {
+        $code = 'simp:true;';
+        $code .= 'a:sqrt(t);';
+        $code .= 'RESULT:ev(a,t=4);';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_ev_3() {
+        $code = 'simp:false;';
+        $code .= 'a:ev(1+1);';
+        $code .= 'RESULT:a;';
+
+        $result = '1+1';
+
+        $this->check($code, $result);
+
+        $code = 'simp:false;';
+        $code .= 'a:ev(1+1,simp);';
+        $code .= 'RESULT:a;';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_ev_4() {
+        $code = 'simp:true;';
+        $code .= 'foo(x):=0+sqrt(x);';
+        $code .= 'RESULT:ev(foo(t),t=4);';
+
+        $result = '2';
+
+        $this->check($code, $result);
+    }
+
+    public function test_iss824() {
+        $code = 'simp:true;';
+        $code .= 'a:2;';
+        $code .= 'u:matrix([t,-1,a*t]);';
+        $code .= 'v:matrix([-1,a+1,5]);';
+        $code .= 'myvar1:ev(t,solve(u.u=1,t));';
+        $code .= 'RESULT:ev(sqrt(u.v), t=myvar1);';
+
+        $result = 'sqrt(3)*%i';
+
+        $this->check($code, $result);
+    }
+
+}