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MDL-27410 qtype_calculated start working on the new code for the ques…
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…tion type.

This is an attempt to start thinking about how to handle the dataset values.
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@timhunt
timhunt committed May 17, 2011
1 parent afe24f8 commit 0652547
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340 changes: 340 additions & 0 deletions question/type/calculated/question.php
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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.

/**
* Calculated question definition class.
*
* @package qtype
* @subpackage calculated
* @copyright 1999 onwards Martin Dougiamas {@link http://moodle.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/


defined('MOODLE_INTERNAL') || die();

require_once($CFG->dirroot . '/question/type/numerical/question.php');


/**
* Represents a calculated question.
*
* @copyright 1999 onwards Martin Dougiamas {@link http://moodle.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class qtype_calculated_question extends qtype_numerical_question {
/** @var qtype_calculated_dataset_loader helper for loading the dataset. */
protected $datasetloader;
/** @var qtype_calculated_variable_substituter stores the dataset we are using. */
protected $vs;

public function start_attempt(question_attempt_step $step) {
$maxnumber = $this->datasetloader->get_number_of_datasets();
$setnumber = rand(1, $maxnumber);
// TODO implement the $synchronizecalculated bit from create_session_and_responses.

$this->vs = $this->datasetloader->load_dataset($setnumber);

$step->set_qt_var('_dataset', $setnumber);
foreach ($this->vs->get_values() as $name => $value) {
$step->set_qt_var('_var_' . $name, $value);
}

$this->calculate_all_expressions();

parent::start_attempt($step);
}

public function apply_attempt_state(question_attempt_step $step) {
$values = array();
foreach ($step->get_qt_datavalues() as $name => $value) {
if (substr($name, 0, 5) === '_var_') {
$values[substr($name, 5)] = $value;
}
}
$this->vs = new qtype_calculated_variable_substituter($values);

$this->calculate_all_expressions();

parent::apply_attempt_state($step);
}

/**
* Replace all the expression in the question definition with the values
* computed from the selected dataset.
*/
protected function calculate_all_expressions() {
$this->questiontext = $this->vs->replace_expressions_in_text($this->questiontext);
$this->generalfeedback = $this->vs->replace_expressions_in_text($this->generalfeedback);
// TODO etc.

foreach ($this->answers as $ans) {
if ($ans->answer && $ans->answer !== '*') {
$ans->answer = $this->vs->calculate($ans->answer);
}
$ans->feedback = $this->vs->replace_expressions_in_text($ans->feedback);
}
}
}


/**
* This class is responsible for loading the dataset that a question needs from
* the database.
*
* @copyright 2011 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class qtype_calculated_dataset_loader {
/** @var int the id of the question we are helping. */
protected $questionid;

/** @var int the id of the question we are helping. */
protected $setsavailable = null;

/**
* Constructor
* @param int $questionid the question to load datasets for.
*/
public function __construct($questionid) {
$this->questionid = $questionid;
}

public function get_number_of_datasets() {
global $DB;

if (is_null($this->setsavailable)) {
$this->setsavailable = $DB->get_field_sql('
SELECT MIN(qdd.itemcount)
FROM {question_dataset_definitions} qdd
JOIN {question_datasets} qd ON qdd.id = qd.datasetdefinition
WHERE qd.question = ?
', array($question->id), MUST_EXIST);
}

return $this->setsavailable;
}

/**
* Load a particular data set.
* @param int $setnumber which set of values to load.
* 0 <= $setnumber < {@link get_number_of_datasets()}.
* @return qtype_calculated_variable_substituter with the correct variable
* -> value substitutions set up.
*/
public function load_dataset($setnumber) {
if ($setnumber <= 0 || $setnumber > $this->get_number_of_datasets()) {
$a = new stdClass();
$a->id = $question->id;
$a->item = $datasetitem;
throw new moodle_exception('cannotgetdsfordependent', 'question', '', $a);
}

$values = $DB->get_records_sql('
SELECT qdd.name, qdi.value
FROM {question_dataset_items} qdi
JOIN {question_dataset_definitions} qdd ON qdd.id = qdi.definition
JOIN {question_datasets} qd ON qdd.id = qd.datasetdefinition
WHERE qd.question = ?
AND qdi.itemnumber = ?
', array($question->id, $setnumber));

return new qtype_calculated_variable_substituter($values);
}
}


/**
* This class holds the current values of all the variables used by a calculated
* question.
*
* It can compute formulae using those values, and can substitute equations
* embedded in text.
*
* @copyright 2011 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class qtype_calculated_variable_substituter {
/** @var array variable name => value */
protected $values;

/** @var array variable names wrapped in {...}. Used by {@link substitute_values()}. */
protected $search;

/**
* @var array variable values, with negative numbers wrapped in (...).
* Used by {@link substitute_values()}.
*/
protected $replace;

/**
* Constructor
* @param array $values variable name => value.
*/
public function __construct(array $values) {
$this->values = $values;

// Prepare an array for {@link substitute_values()}.
$this->search = array();
$this->replace = array();
foreach ($values as $name => $value) {
if (!is_numeric($value)) {
$a = new stdClass();
$a->name = '{' . $name . '}';
$a->value = $value;
throw new moodle_exception('notvalidnumber', 'qtype_calculated', '', $a);
}

$this->search[] = '{' . $name . '}';
if ($value < 0) {
$this->replace[] = '(' . $value . ')';
} else {
$this->replace[] = $value;
}
}
}

/**
* Return an array of the variables and their values.
* @return array name => value.
*/
public function get_values() {
return clone($this->values);
}

/**
* Evaluate an expression using the variable values.
* @param string $expression the expression. A PHP expression with placeholders
* like {a} for where the variables need to go.
* @return float the computed result.
*/
public function calculate($expression) {
eval('$str = ' . $this->substitute_values($expression) . ';');
return $str;
}

/**
* Substitute variable placehodlers like {a} with their value.
* @param string $expression the expression. A PHP expression with placeholders
* like {a} for where the variables need to go.
* @return string the expression with each placeholder replaced by the
* corresponding value.
*/
protected function substitute_values($expression) {
return str_replace($this->search, $this->replace, $expression);
}

public function replace_expressions_in_text($text) {
// TODO
return $text;
}

/**
* Return an array describing any problems there are with an expression.
* Returns false if the expression is fine.
* @param string $formula an expression.
* @return array|false list of problems, or false if the exression is OK.
*/
public function get_formula_errors($formula) {
// Validates the formula submitted from the question edit page.
// Returns false if everything is alright.
// Otherwise it constructs an error message
// Strip away dataset names
while (preg_match('~\\{[[:alpha:]][^>} <{"\']*\\}~', $formula, $regs)) {
$formula = str_replace($regs[0], '1', $formula);
}

// Strip away empty space and lowercase it
$formula = strtolower(str_replace(' ', '', $formula));

$safeoperatorchar = '-+/*%>:^\~<?=&|!'; /* */
$operatorornumber = "[$safeoperatorchar.0-9eE]";

while (preg_match("~(^|[$safeoperatorchar,(])([a-z0-9_]*)" .
"\\(($operatorornumber+(,$operatorornumber+((,$operatorornumber+)+)?)?)?\\)~",
$formula, $regs)) {
switch ($regs[2]) {
// Simple parenthesis
case '':
if ((isset($regs[4]) && $regs[4]) || strlen($regs[3]) == 0) {
return get_string('illegalformulasyntax', 'qtype_calculated', $regs[0]);
}
break;

// Zero argument functions
case 'pi':
if ($regs[3]) {
return get_string('functiontakesnoargs', 'qtype_calculated', $regs[2]);
}
break;

// Single argument functions (the most common case)
case 'abs': case 'acos': case 'acosh': case 'asin': case 'asinh':
case 'atan': case 'atanh': case 'bindec': case 'ceil': case 'cos':
case 'cosh': case 'decbin': case 'decoct': case 'deg2rad':
case 'exp': case 'expm1': case 'floor': case 'is_finite':
case 'is_infinite': case 'is_nan': case 'log10': case 'log1p':
case 'octdec': case 'rad2deg': case 'sin': case 'sinh': case 'sqrt':
case 'tan': case 'tanh':
if (!empty($regs[4]) || empty($regs[3])) {
return get_string('functiontakesonearg', 'qtype_calculated', $regs[2]);
}
break;

// Functions that take one or two arguments
case 'log': case 'round':
if (!empty($regs[5]) || empty($regs[3])) {
return get_string('functiontakesoneortwoargs', 'qtype_calculated', $regs[2]);
}
break;

// Functions that must have two arguments
case 'atan2': case 'fmod': case 'pow':
if (!empty($regs[5]) || empty($regs[4])) {
return get_string('functiontakestwoargs', 'qtype_calculated', $regs[2]);
}
break;

// Functions that take two or more arguments
case 'min': case 'max':
if (empty($regs[4])) {
return get_string('functiontakesatleasttwo', 'qtype_calculated', $regs[2]);
}
break;

default:
return get_string('unsupportedformulafunction', 'qtype_calculated', $regs[2]);
}

// Exchange the function call with '1' and then chack for
// another function call...
if ($regs[1]) {
// The function call is proceeded by an operator
$formula = str_replace($regs[0], $regs[1] . '1', $formula);
} else {
// The function call starts the formula
$formula = preg_replace("~^$regs[2]\\([^)]*\\)~", '1', $formula);
}
}

if (preg_match("~[^$safeoperatorchar.0-9eE]+~", $formula, $regs)) {
return get_string('illegalformulasyntax', 'qtype_calculated', $regs[0]);
} else {
// Formula just might be valid
return false;
}
}
}
6 changes: 4 additions & 2 deletions question/type/calculated/questiontype.php
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Expand Up @@ -1414,9 +1414,11 @@ public function multichoice_comment_on_datasetitems($questionid, $questiontext,
}

public function tolerance_types() {
return array('1' => get_string('relative', 'qtype_numerical'),
return array(
'1' => get_string('relative', 'qtype_numerical'),
'2' => get_string('nominal', 'qtype_numerical'),
'3' => get_string('geometric', 'qtype_numerical'));
'3' => get_string('geometric', 'qtype_numerical')
);
}

public function dataset_options($form, $name, $mandatory = true,
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37 changes: 37 additions & 0 deletions question/type/calculated/renderer.php
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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle 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.
//
// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.

/**
* Calculated question renderer class.
*
* @package qtype
* @subpackage calculated
* @copyright 1999 onwards Martin Dougiamas {@link http://moodle.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/


defined('MOODLE_INTERNAL') || die();


/**
* Generates the output for calculated questions.
*
* @copyright 1999 onwards Martin Dougiamas {@link http://moodle.com}
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class qtype_calculated_renderer extends qtype_numerical_renderer {
}

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