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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/>.
/**
* This file defines the class {@link question_definition} and its subclasses.
*
* @package moodlecore
* @subpackage questiontypes
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
/**
* The definition of a question of a particular type.
*
* This class is a close match to the question table in the database.
* Definitions of question of a particular type normally subclass one of the
* more specific classes {@link question_with_responses},
* {@link question_graded_automatically} or {@link question_information_item}.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class question_definition {
/** @var integer id of the question in the datase, or null if this question
* is not in the database. */
public $id;
/** @var integer question category id. */
public $category;
/** @var integer question context id. */
public $contextid;
/** @var integer parent question id. */
public $parent = 0;
/** @var question_type the question type this question is. */
public $qtype;
/** @var string question name. */
public $name;
/** @var string question text. */
public $questiontext;
/** @var integer question test format. */
public $questiontextformat;
/** @var string question general feedback. */
public $generalfeedback;
/** @var integer question test format. */
public $generalfeedbackformat;
/** @var number what this quetsion is marked out of, by default. */
public $defaultmark = 1;
/** @var integer How many question numbers this question consumes. */
public $length = 1;
/** @var number penalty factor of this question. */
public $penalty = 0;
/** @var string unique identifier of this question. */
public $stamp;
/** @var string unique identifier of this version of this question. */
public $version;
/** @var boolean whethre this question has been deleted/hidden in the question bank. */
public $hidden = 0;
/** @var integer timestamp when this question was created. */
public $timecreated;
/** @var integer timestamp when this question was modified. */
public $timemodified;
/** @var integer userid of the use who created this question. */
public $createdby;
/** @var integer userid of the use who modified this question. */
public $modifiedby;
/** @var array of question_hints. */
public $hints = array();
/**
* Constructor. Normally to get a question, you call
* {@link question_bank::load_question()}, but questions can be created
* directly, for example in unit test code.
* @return unknown_type
*/
public function __construct() {
}
/**
* @return the name of the question type (for example multichoice) that this
* question is.
*/
public function get_type_name() {
return $this->qtype->name();
}
/**
* Creat the appropriate behaviour for an attempt at this quetsion,
* given the desired (archetypal) behaviour.
*
* This default implementation will suit most normal graded questions.
*
* If your question is of a patricular type, then it may need to do something
* different. For example, if your question can only be graded manually, then
* it should probably return a manualgraded behaviour, irrespective of
* what is asked for.
*
* If your question wants to do somthing especially complicated is some situations,
* then you may wish to return a particular behaviour related to the
* one asked for. For example, you migth want to return a
* qbehaviour_interactive_adapted_for_myqtype.
*
* @param question_attempt $qa the attempt we are creating an behaviour for.
* @param string $preferredbehaviour the requested type of behaviour.
* @return question_behaviour the new behaviour object.
*/
public function make_behaviour(question_attempt $qa, $preferredbehaviour) {
return question_engine::make_archetypal_behaviour($preferredbehaviour, $qa);
}
/**
* Start a new attempt at this question, storing any information that will
* be needed later in the step.
*
* This is where the question can do any initialisation required on a
* per-attempt basis. For example, this is where the multiple choice
* question type randomly shuffles the choices (if that option is set).
*
* Any information about how the question has been set up for this attempt
* should be stored in the $step, by calling $step->set_qt_var(...).
*
* @param question_attempt_step The first step of the {@link question_attempt}
* being started. Can be used to store state.
* @param int $varant which variant of this question to start. Will be between
* 1 and {@link get_num_variants()} inclusive.
*/
public function start_attempt(question_attempt_step $step, $variant) {
}
/**
* When an in-progress {@link question_attempt} is re-loaded from the
* database, this method is called so that the question can re-initialise
* its internal state as needed by this attempt.
*
* For example, the multiple choice question type needs to set the order
* of the choices to the order that was set up when start_attempt was called
* originally. All the information required to do this should be in the
* $step object, which is the first step of the question_attempt being loaded.
*
* @param question_attempt_step The first step of the {@link question_attempt}
* being loaded.
*/
public function apply_attempt_state(question_attempt_step $step) {
}
/**
* Generate a brief, plain-text, summary of this question. This is used by
* various reports. This should show the particular variant of the question
* as presented to students. For example, the calculated quetsion type would
* fill in the particular numbers that were presented to the student.
* This method will return null if such a summary is not possible, or
* inappropriate.
* @return string|null a plain text summary of this question.
*/
public function get_question_summary() {
return $this->html_to_text($this->questiontext, $this->questiontextformat);
}
/**
* @return int the number of vaiants that this question has.
*/
public function get_num_variants() {
return 1;
}
/**
* @return string that can be used to seed the pseudo-random selection of a
* variant.
*/
public function get_variants_selection_seed() {
return $this->stamp;
}
/**
* Some questions can return a negative mark if the student gets it wrong.
*
* This method returns the lowest mark the question can return, on the
* fraction scale. that is, where the maximum possible mark is 1.0.
*
* @return number minimum fraction this question will ever return.
*/
public function get_min_fraction() {
return 0;
}
/**
* Given a response, rest the parts that are wrong.
* @param array $response a response
* @return array a cleaned up response with the wrong bits reset.
*/
public function clear_wrong_from_response(array $response) {
return array();
}
/**
* Return the number of subparts of this response that are right.
* @param array $response a response
* @return array with two elements, the number of correct subparts, and
* the total number of subparts.
*/
public function get_num_parts_right(array $response) {
return array(null, null);
}
/**
* @param moodle_page the page we are outputting to.
* @return qtype_renderer the renderer to use for outputting this question.
*/
public function get_renderer(moodle_page $page) {
return $page->get_renderer($this->qtype->plugin_name());
}
/**
* What data may be included in the form submission when a student submits
* this question in its current state?
*
* This information is used in calls to optional_param. The parameter name
* has {@link question_attempt::get_field_prefix()} automatically prepended.
*
* @return array|string variable name => PARAM_... constant, or, as a special case
* that should only be used in unavoidable, the constant question_attempt::USE_RAW_DATA
* meaning take all the raw submitted data belonging to this question.
*/
public abstract function get_expected_data();
/**
* What data would need to be submitted to get this question correct.
* If there is more than one correct answer, this method should just
* return one possibility. If it is not possible to compute a correct
* response, this method should return null.
*
* @return array|null parameter name => value.
*/
public abstract function get_correct_response();
/**
* Apply {@link format_text()} to some content with appropriate settings for
* this question.
*
* @param string $text some content that needs to be output.
* @param int $format the FORMAT_... constant.
* @param question_attempt $qa the question attempt.
* @param string $component used for rewriting file area URLs.
* @param string $filearea used for rewriting file area URLs.
* @param bool $clean Whether the HTML needs to be cleaned. Generally,
* parts of the question do not need to be cleaned, and student input does.
* @return string the text formatted for output by format_text.
*/
public function format_text($text, $format, $qa, $component, $filearea, $itemid,
$clean = false) {
$formatoptions = new stdClass();
$formatoptions->noclean = !$clean;
$formatoptions->para = false;
$text = $qa->rewrite_pluginfile_urls($text, $component, $filearea, $itemid);
return format_text($text, $format, $formatoptions);
}
/**
* Convert some part of the question text to plain text. This might be used,
* for example, by get_response_summary().
* @param string $text The HTML to reduce to plain text.
* @param int $format the FORMAT_... constant.
* @return string the equivalent plain text.
*/
public function html_to_text($text, $format) {
return html_to_text(format_text($text, $format, array('noclean' => true)), 0, false);
}
/** @return the result of applying {@link format_text()} to the question text. */
public function format_questiontext($qa) {
return $this->format_text($this->questiontext, $this->questiontextformat,
$qa, 'question', 'questiontext', $this->id);
}
/** @return the result of applying {@link format_text()} to the general feedback. */
public function format_generalfeedback($qa) {
return $this->format_text($this->generalfeedback, $this->generalfeedbackformat,
$qa, 'question', 'generalfeedback', $this->id);
}
/**
* Checks whether the users is allow to be served a particular file.
* @param question_attempt $qa the question attempt being displayed.
* @param question_display_options $options the options that control display of the question.
* @param string $component the name of the component we are serving files for.
* @param string $filearea the name of the file area.
* @param array $args the remaining bits of the file path.
* @param bool $forcedownload whether the user must be forced to download the file.
* @return bool true if the user can access this file.
*/
public function check_file_access($qa, $options, $component, $filearea, $args, $forcedownload) {
if ($component == 'question' && $filearea == 'questiontext') {
// Question text always visible.
return true;
} else if ($component == 'question' && $filearea == 'generalfeedback') {
return $options->generalfeedback;
} else {
// Unrecognised component or filearea.
return false;
}
}
}
/**
* This class represents a 'question' that actually does not allow the student
* to respond, like the description 'question' type.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class question_information_item extends question_definition {
public function __construct() {
parent::__construct();
$this->defaultmark = 0;
$this->penalty = 0;
$this->length = 0;
}
public function make_behaviour(question_attempt $qa, $preferredbehaviour) {
question_engine::load_behaviour_class('informationitem');
return new qbehaviour_informationitem($qa, $preferredbehaviour);
}
public function get_expected_data() {
return array();
}
public function get_correct_response() {
return array();
}
public function get_question_summary() {
return null;
}
}
/**
* Interface that a {@link question_definition} must implement to be usable by
* the manual graded behaviour.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
interface question_manually_gradable {
/**
* Used by many of the behaviours, to work out whether the student's
* response to the question is complete. That is, whether the question attempt
* should move to the COMPLETE or INCOMPLETE state.
*
* @param array $response responses, as returned by
* {@link question_attempt_step::get_qt_data()}.
* @return bool whether this response is a complete answer to this question.
*/
public function is_complete_response(array $response);
/**
* Use by many of the behaviours to determine whether the student's
* response has changed. This is normally used to determine that a new set
* of responses can safely be discarded.
*
* @param array $prevresponse the responses previously recorded for this question,
* as returned by {@link question_attempt_step::get_qt_data()}
* @param array $newresponse the new responses, in the same format.
* @return bool whether the two sets of responses are the same - that is
* whether the new set of responses can safely be discarded.
*/
public function is_same_response(array $prevresponse, array $newresponse);
/**
* Produce a plain text summary of a response.
* @param $response a response, as might be passed to {@link grade_response()}.
* @return string a plain text summary of that response, that could be used in reports.
*/
public function summarise_response(array $response);
/**
* Categorise the student's response according to the categories defined by
* get_possible_responses.
* @param $response a response, as might be passed to {@link grade_response()}.
* @return array subpartid => {@link question_classified_response} objects.
* returns an empty array if no analysis is possible.
*/
public function classify_response(array $response);
}
/**
* This class is used in the return value from
* {@link question_manually_gradable::classify_response()}.
*
* @copyright 2010 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class question_classified_response {
/**
* @var string the classification of this response the student gave to this
* part of the question. Must match one of the responseclasses returned by
* {@link question_type::get_possible_responses()}.
*/
public $responseclassid;
/** @var string the actual response the student gave to this part. */
public $response;
/** @var number the fraction this part of the response earned. */
public $fraction;
/**
* Constructor, just an easy way to set the fields.
* @param string $responseclassid see the field descriptions above.
* @param string $response see the field descriptions above.
* @param number $fraction see the field descriptions above.
*/
public function __construct($responseclassid, $response, $fraction) {
$this->responseclassid = $responseclassid;
$this->response = $response;
$this->fraction = $fraction;
}
public static function no_response() {
return new question_classified_response(null, get_string('noresponse', 'question'), null);
}
}
/**
* Interface that a {@link question_definition} must implement to be usable by
* the various automatic grading behaviours.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
interface question_automatically_gradable extends question_manually_gradable {
/**
* Use by many of the behaviours to determine whether the student
* has provided enough of an answer for the question to be graded automatically,
* or whether it must be considered aborted.
*
* @param array $response responses, as returned by
* {@link question_attempt_step::get_qt_data()}.
* @return bool whether this response can be graded.
*/
public function is_gradable_response(array $response);
/**
* In situations where is_gradable_response() returns false, this method
* should generate a description of what the problem is.
* @return string the message.
*/
public function get_validation_error(array $response);
/**
* Grade a response to the question, returning a fraction between
* get_min_fraction() and 1.0, and the corresponding {@link question_state}
* right, partial or wrong.
* @param array $response responses, as returned by
* {@link question_attempt_step::get_qt_data()}.
* @return array (number, integer) the fraction, and the state.
*/
public function grade_response(array $response);
/**
* Get one of the question hints. The question_attempt is passed in case
* the question type wants to do something complex. For example, the
* multiple choice with multiple responses question type will turn off most
* of the hint options if the student has selected too many opitions.
* @param int $hintnumber Which hint to display. Indexed starting from 0
* @param question_attempt $qa The question_attempt.
*/
public function get_hint($hintnumber, question_attempt $qa);
/**
* Generate a brief, plain-text, summary of the correct answer to this question.
* This is used by various reports, and can also be useful when testing.
* This method will return null if such a summary is not possible, or
* inappropriate.
* @return string|null a plain text summary of the right answer to this question.
*/
public function get_right_answer_summary();
}
/**
* Interface that a {@link question_definition} must implement to be usable by
* the interactivecountback behaviour.
*
* @copyright 2010 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
interface question_automatically_gradable_with_countback extends question_automatically_gradable {
/**
* Work out a final grade for this attempt, taking into account all the
* tries the student made.
* @param array $responses the response for each try. Each element of this
* array is a response array, as would be passed to {@link grade_response()}.
* There may be between 1 and $totaltries responses.
* @param int $totaltries The maximum number of tries allowed.
* @return numeric the fraction that should be awarded for this
* sequence of response.
*/
public function compute_final_grade($responses, $totaltries);
}
/**
* This class represents a real question. That is, one that is not a
* {@link question_information_item}.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class question_with_responses extends question_definition
implements question_manually_gradable {
public function classify_response(array $response) {
return array();
}
}
/**
* This class represents a question that can be graded automatically.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class question_graded_automatically extends question_with_responses
implements question_automatically_gradable {
/** @var Some question types have the option to show the number of sub-parts correct. */
public $shownumcorrect = false;
public function is_gradable_response(array $response) {
return $this->is_complete_response($response);
}
public function get_right_answer_summary() {
$correctresponse = $this->get_correct_response();
if (empty($correctresponse)) {
return null;
}
return $this->summarise_response($correctresponse);
}
/**
* Check a request for access to a file belonging to a combined feedback field.
* @param question_attempt $qa the question attempt being displayed.
* @param question_display_options $options the options that control display of the question.
* @param string $filearea the name of the file area.
* @return bool whether access to the file should be allowed.
*/
protected function check_combined_feedback_file_access($qa, $options, $filearea) {
$state = $qa->get_state();
if (!$state->is_finished()) {
$response = $qa->get_last_qt_data();
if (!$this->is_gradable_response($response)) {
return false;
}
list($notused, $state) = $this->grade_response($response);
}
return $options->feedback && $state->get_feedback_class() . 'feedback' == $filearea;
}
/**
* Check a request for access to a file belonging to a hint.
* @param question_attempt $qa the question attempt being displayed.
* @param question_display_options $options the options that control display of the question.
* @param array $args the remaining bits of the file path.
* @return bool whether access to the file should be allowed.
*/
protected function check_hint_file_access($qa, $options, $args) {
if (!$options->feedback) {
return false;
}
$hint = $qa->get_applicable_hint();
$hintid = reset($args); // itemid is hint id.
return $hintid == $hint->id;
}
public function get_hint($hintnumber, question_attempt $qa) {
if (!isset($this->hints[$hintnumber])) {
return null;
}
return $this->hints[$hintnumber];
}
public function format_hint(question_hint $hint, question_attempt $qa) {
return $this->format_text($hint->hint, $hint->hintformat, $qa,
'question', 'hint', $hint->id);
}
}
/**
* This class represents a question that can be graded automatically with
* countback grading in interactive mode.
*
* @copyright 2010 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class question_graded_automatically_with_countback
extends question_graded_automatically
implements question_automatically_gradable_with_countback {
public function make_behaviour(question_attempt $qa, $preferredbehaviour) {
if ($preferredbehaviour == 'interactive') {
return question_engine::make_behaviour('interactivecountback',
$qa, $preferredbehaviour);
}
return question_engine::make_archetypal_behaviour($preferredbehaviour, $qa);
}
}
/**
* This class represents a question that can be graded automatically by using
* a {@link question_grading_strategy}.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class question_graded_by_strategy extends question_graded_automatically {
/** @var question_grading_strategy the strategy to use for grading. */
protected $gradingstrategy;
/** @param question_grading_strategy $strategy the strategy to use for grading. */
public function __construct(question_grading_strategy $strategy) {
parent::__construct();
$this->gradingstrategy = $strategy;
}
public function get_correct_response() {
$answer = $this->get_correct_answer();
if (!$answer) {
return array();
}
return array('answer' => $answer->answer);
}
/**
* Get an answer that contains the feedback and fraction that should be
* awarded for this resonse.
* @param array $response a response.
* @return question_answer the matching answer.
*/
public function get_matching_answer(array $response) {
return $this->gradingstrategy->grade($response);
}
/**
* @return question_answer an answer that contains the a response that would
* get full marks.
*/
public function get_correct_answer() {
return $this->gradingstrategy->get_correct_answer();
}
public function grade_response(array $response) {
$answer = $this->get_matching_answer($response);
if ($answer) {
return array($answer->fraction,
question_state::graded_state_for_fraction($answer->fraction));
} else {
return array(0, question_state::$gradedwrong);
}
}
public function classify_response(array $response) {
if (empty($response['answer'])) {
return array($this->id => question_classified_response::no_response());
}
$ans = $this->get_matching_answer($response);
if (!$ans) {
return array($this->id => new question_classified_response(
0, $response['answer'], 0));
}
return array($this->id => new question_classified_response(
$ans->id, $response['answer'], $ans->fraction));
}
}
/**
* Class to represent a question answer, loaded from the question_answers table
* in the database.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class question_answer {
/** @var integer the answer id. */
public $id;
/** @var string the answer. */
public $answer;
/** @var integer one of the FORMAT_... constans. */
public $answerformat = FORMAT_PLAIN;
/** @var number the fraction this answer is worth. */
public $fraction;
/** @var string the feedback for this answer. */
public $feedback;
/** @var integer one of the FORMAT_... constans. */
public $feedbackformat;
/**
* Constructor.
* @param int $id the answer.
* @param string $answer the answer.
* @param int $answerformat the format of the answer.
* @param number $fraction the fraction this answer is worth.
* @param string $feedback the feedback for this answer.
* @param int $feedbackformat the format of the feedback.
*/
public function __construct($id, $answer, $fraction, $feedback, $feedbackformat) {
$this->id = $id;
$this->answer = $answer;
$this->fraction = $fraction;
$this->feedback = $feedback;
$this->feedbackformat = $feedbackformat;
}
}
/**
* Class to represent a hint associated with a question.
* Used by iteractive mode, etc. A question has an array of these.
*
* @copyright 2010 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class question_hint {
/** @var integer The hint id. */
public $id;
/** @var string The feedback hint to be shown. */
public $hint;
/** @var integer The corresponding text FORMAT_... type. */
public $hintformat;
/**
* Constructor.
* @param int the hint id from the database.
* @param string $hint The hint text
* @param int the corresponding text FORMAT_... type.
*/
public function __construct($id, $hint, $hintformat) {
$this->id = $id;
$this->hint = $hint;
$this->hintformat = $hintformat;
}
/**
* Create a basic hint from a row loaded from the question_hints table in the database.
* @param object $row with $row->hint set.
* @return question_hint
*/
public static function load_from_record($row) {
return new question_hint($row->id, $row->hint, $row->hintformat);
}
/**
* Adjust this display options according to the hint settings.
* @param question_display_options $options
*/
public function adjust_display_options(question_display_options $options) {
// Do nothing.
}
}
/**
* An extension of {@link question_hint} for questions like match and multiple
* choice with multile answers, where there are options for whether to show the
* number of parts right at each stage, and to reset the wrong parts.
*
* @copyright 2010 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class question_hint_with_parts extends question_hint {
/** @var boolean option to show the number of sub-parts of the question that were right. */
public $shownumcorrect;
/** @var boolean option to clear the parts of the question that were wrong on retry. */
public $clearwrong;
/**
* Constructor.
* @param int the hint id from the database.
* @param string $hint The hint text
* @param int the corresponding text FORMAT_... type.
* @param bool $shownumcorrect whether the number of right parts should be shown
* @param bool $clearwrong whether the wrong parts should be reset.
*/
public function __construct($id, $hint, $hintformat, $shownumcorrect, $clearwrong) {
parent::__construct($id, $hint, $hintformat);
$this->shownumcorrect = $shownumcorrect;
$this->clearwrong = $clearwrong;
}
/**
* Create a basic hint from a row loaded from the question_hints table in the database.
* @param object $row with $row->hint, ->shownumcorrect and ->clearwrong set.
* @return question_hint_with_parts
*/
public static function load_from_record($row) {
return new question_hint_with_parts($row->id, $row->hint, $row->hintformat,
$row->shownumcorrect, $row->clearwrong);
}
public function adjust_display_options(question_display_options $options) {
parent::adjust_display_options($options);
if ($this->clearwrong) {
$options->clearwrong = true;
}
$options->numpartscorrect = $this->shownumcorrect;
}
}
/**
* This question_grading_strategy interface. Used to share grading code between
* questions that that subclass {@link question_graded_by_strategy}.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
interface question_grading_strategy {
/**
* Return a question answer that describes the outcome (fraction and feeback)
* for a particular respons.
* @param array $response the response.
* @return question_answer the answer describing the outcome.
*/
public function grade(array $response);
/**
* @return question_answer an answer that contains the a response that would
* get full marks.
*/
public function get_correct_answer();
}
/**
* This interface defines the methods that a {@link question_definition} must
* implement if it is to be graded by the
* {@link question_first_matching_answer_grading_strategy}.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
interface question_response_answer_comparer {
/** @return array of {@link question_answers}. */
public function get_answers();
/**
* @param array $response the response.
* @param question_answer $answer an answer.
* @return bool whether the response matches the answer.
*/
public function compare_response_with_answer(array $response, question_answer $answer);
}
/**
* This grading strategy is used by question types like shortanswer an numerical.
* It gets a list of possible answers from the question, and returns the first one
* that matches the given response. It returns the first answer with fraction 1.0
* when asked for the correct answer.
*
* @copyright 2009 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
class question_first_matching_answer_grading_strategy implements question_grading_strategy {
/**
* @var question_response_answer_comparer (presumably also a
* {@link question_definition}) the question we are doing the grading for.
*/
protected $question;
/**
* @param question_response_answer_comparer $question (presumably also a
* {@link question_definition}) the question we are doing the grading for.
*/
public function __construct(question_response_answer_comparer $question) {
$this->question = $question;
}
public function grade(array $response) {
foreach ($this->question->get_answers() as $aid => $answer) {
if ($this->question->compare_response_with_answer($response, $answer)) {
$answer->id = $aid;
return $answer;
}
}
return null;
}
public function get_correct_answer() {
foreach ($this->question->get_answers() as $answer) {
$state = question_state::graded_state_for_fraction($answer->fraction);
if ($state == question_state::$gradedright) {
return $answer;
}
}
return null;
}
}
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