<?php  // $Id: questiontype.php,v 1.7.2.6 2006/10/03 18:00:23 tjhunt Exp $

///////////////////
/// MULTIANSWER /// (Embedded - cloze)
///////////////////

///
/// The multianswer question type is special in that it
/// depends on a few other question types, i.e.
/// 'multichoice', 'shortanswer' and 'numerical'.
/// These question types have got a few special features that
/// makes them useable by the 'multianswer' question type
///

/// QUESTION TYPE CLASS //////////////////
class embedded_cloze_qtype extends default_questiontype {

    function name() {
        return 'multianswer';
    }

    function get_question_options(&$question) {
        global $QTYPES;

        // Get relevant data indexed by positionkey from the multianswers table
        if (!$sequence = get_field('question_multianswer', 'sequence', 'question', $question->id)) {
            notify('Error: Cloze question '.$question->id.' is missing question options!');
            return false;
        }

        $wrappedquestions = get_records_list('question', 'id', $sequence);

        // We want an array with question ids as index and the positions as values
        $sequence = array_flip(explode(',', $sequence));
        array_walk($sequence, create_function('&$val', '$val++;'));

        foreach ($wrappedquestions as $wrapped) {
            if (!$QTYPES[$wrapped->qtype]->get_question_options($wrapped)) {
                notify("Unable to get options for questiontype {$wrapped->qtype} (id={$wrapped->id})");
            }
            // for wrapped questions the maxgrade is always equal to the defaultgrade,
            // there is no entry in the question_instances table for them
            $wrapped->maxgrade = $wrapped->defaultgrade;
            
            $question->options->questions[$sequence[$wrapped->id]] = clone($wrapped); // ??? Why do we need a clone here?
        }

        return true;
    }

    function save_question_options($question) {
        global $QTYPES;
        $result = new stdClass;
        
        // This function needs to be able to handle the case where the existing set of wrapped
        // questions does not match the new set of wrapped questions so that some need to be
        // created, some modified and some deleted
        // Unfortunately the code currently simply overwrites existing ones in sequence. This
        // will make re-marking after a re-ordering of wrapped questions impossible and 
        // will also create difficulties if questiontype specific tables reference the id.
        
        // First we get all the existing wrapped questions
        if (!$oldwrappedids = get_field('question_multianswer', 'sequence', 'question', $question->id)) {
            $oldwrappedids = array();
        } else {
            $oldwrappedids = explode(',', $oldwrappedids);
        }
        $sequence = array();
        foreach($question->options->questions as $wrapped) {
            // if we still have some old wrapped question ids, reuse the next of them
            if ($oldwrappedid = array_shift($oldwrappedids)) {
                $wrapped->id = $oldwrappedid;
            }
            $wrapped->name     = $question->name;
            $wrapped->parent   = $question->id;
            $wrapped->category = $question->category;
            $wrapped = $QTYPES[$wrapped->qtype]->save_question($wrapped,
             $wrapped, $question->course);
            $sequence[] = $wrapped->id;
        }

        // Delete redundant wrapped questions
        $oldwrappedids = implode(',', $oldwrappedids);
        delete_records_select('question', "id IN ($oldwrappedids)");

        if (!empty($sequence)) {
            $multianswer = new stdClass;
            $multianswer->question = $question->id;
            $multianswer->sequence = implode(',', $sequence);
            if ($oldid =
             get_field('question_multianswer', 'id', 'question', $question->id)) {
                $multianswer->id = $oldid;
                if (!update_record("question_multianswer", $multianswer)) {
                    $result->error = "Could not update cloze question options! " .
                     "(id=$multianswer->id)";
                    return $result;
                }
            } else {
                if (!insert_record("question_multianswer", $multianswer)) {
                    $result->error = "Could not insert cloze question options!";
                    return $result;
                }
            }
        }
    }

    function save_question($authorizedquestion, $form, $course) {
        $question = qtype_multianswer_extract_question ($form->questiontext);
        if (isset($authorizedquestion->id)) {
            $question->id = $authorizedquestion->id;
        }


        $question->category = $authorizedquestion->category;
        $form->course = $course; // To pass the course object to
                                 // save_question_options, where it is
                                 // needed to call type specific
                                 // save_question methods.
        $form->defaultgrade = $question->defaultgrade;
        $form->questiontext = $question->questiontext;
        $form->questiontextformat = 0;
        $form->options      = clone($question->options);
        unset($question->options);
        return parent::save_question($question, $form, $course);
    }

    function create_session_and_responses(&$question, &$state, $cmoptions, $attempt) {
        $state->responses = array();
        foreach ($question->options->questions as $key => $wrapped) {
            $state->responses[$key] = '';
        }
        return true;
    }

    function restore_session_and_responses(&$question, &$state) {
        $responses = explode(',', $state->responses['']);
        $state->responses = array();
        foreach ($responses as $response) {
            $tmp = explode("-", $response);
            // restore encoded characters
            $state->responses[$tmp[0]] =
             str_replace(array("&#0044;", "&#0045;"), array(",", "-"), $tmp[1]);
        }
        return true;
    }

    function save_session_and_responses(&$question, &$state) {
        $responses = $state->responses;
        array_walk($responses, create_function('&$val, $key',
         // encode - (hyphen) and , (comma) to &#0045; because they are used as
         // delimiters
         '$val = str_replace(array(",", "-"), array("&#0044;", "&#0045;"), $val);
          $val = "$key-$val";'));
        $responses = implode(',', $responses);

        // Set the legacy answer field
        if (!set_field('question_states', 'answer', $responses, 'id',
         $state->id)) {
            return false;
        }
        return true;
    }

    /**
    * Deletes question from the question-type specific tables
    *
    * @return boolean Success/Failure
    * @param object $question  The question being deleted
    */
    function delete_question($questionid) {
        delete_records("question_multianswer", "question", $questionid);
        return true;
    }

    function get_correct_responses(&$question, &$state) {
        global $QTYPES;
        $responses = array();
        foreach($question->options->questions as $key => $wrapped) {
            if ($correct = $QTYPES[$wrapped->qtype]->get_correct_responses($wrapped, $state)) {
                $responses[$key] = $correct[''];
            } else {
                // if there is no correct answer to this subquestion then there
                // can not be a correct answer to the whole question either, so
                // we have to return null.
                return null;
            }
        }
        return $responses;
    }

    function print_question_formulation_and_controls(&$question, &$state, $cmoptions, $options) {
        global $QTYPES;
        $readonly = empty($options->readonly) ? '' : 'readonly="readonly"';
        $disabled = empty($options->readonly) ? '' : 'disabled="disabled"';
        $formatoptions = new stdClass;
        $formatoptions->noclean = true;
        $formatoptions->para = false;
        $nameprefix = $question->name_prefix;

        // For this question type, we better print the image on top:
        if ($image = get_question_image($question, $cmoptions->course)) {
            echo('<img class="qimage" src="' . $image . '" alt="" /><br />');
        }

        $qtextremaining = format_text($question->questiontext,
                                      $question->questiontextformat,
                                      $formatoptions, $cmoptions->course);

        $strfeedback = get_string('feedback', 'quiz');

        // The regex will recognize text snippets of type {#X}
        // where the X can be any text not containg } or white-space characters.

        while (ereg('\{#([^[:space:]}]*)}', $qtextremaining, $regs)) {
            $qtextsplits = explode($regs[0], $qtextremaining, 2);
            echo $qtextsplits[0];
            $qtextremaining = $qtextsplits[1];

            $positionkey = $regs[1];
            $wrapped = &$question->options->questions[$positionkey];
            $answers = &$wrapped->options->answers;
            $correctanswers = $QTYPES[$wrapped->qtype]
             ->get_correct_responses($wrapped, $state);

            $inputname = $nameprefix.$positionkey;
            $response = isset($state->responses[$positionkey])
                    ? $state->responses[$positionkey] : null;


            // Determine feedback popup if any
            $popup = '';
            $style = '';
            if ($options->feedback) {
                $chosenanswer = null;
                switch ($wrapped->qtype) {
                    case 'numerical':
                        $testedstate = clone($state);
                        $testedstate->responses[''] = $response;
                        foreach ($answers as $answer) {
                            if($QTYPES[$wrapped->qtype]
                                    ->test_response($wrapped, $testedstate, $answer)) {
                                $chosenanswer = clone($answer);
                                break;
                            }
                        }
                        break;
                    case 'shortanswer':
                        $testedstate = clone($state);
                        $testedstate->responses[''] = $response;
                        $teststate   = clone($state);
                        foreach ($answers as $answer) {
                            $teststate->responses[''] = trim($answer->answer);
                            if($QTYPES[$wrapped->qtype]
                                    ->compare_responses($wrapped, $testedstate, $teststate)) {
                                $chosenanswer = clone($answer);
                                break;
                            }
                        }
                        break;
                    case 'multichoice':
                        if (isset($answers[$response])) {
                            $chosenanswer = clone($answers[$response]);
                        }
                        break;
                    default:
                        break;
                }

                // Set up a default chosenanswer so that all non-empty wrong
                // answers are highlighted red
                if (empty($chosenanswer) && !empty($response)) {
                    $chosenanswer = new stdClass;
                    $chosenanswer->fraction = 0.0;
                }

                if (!empty($chosenanswer->feedback)) {
                    $feedback = str_replace("'", "\\'", $chosenanswer->feedback);
                    $popup = " onmouseover=\"return overlib('$feedback', STICKY, MOUSEOFF, CAPTION, '$strfeedback', FGCOLOR, '#FFFFFF');\" ".
                             " onmouseout=\"return nd();\" ";
                }

                /// Determine style
                if (!empty($chosenanswer) && $options->correct_responses) {
                    if (!isset($chosenanswer->fraction)
                            || $chosenanswer->fraction <= 0.0) {
                        // The response must have been totally wrong:
                        $style = 'class="incorrect"';

                    } else if ($chosenanswer->fraction >= 1.0) {
                        // The response was correct!!
                        $style = 'class="correct"';

                    } else {
                        // This response did at least give some credit:
                        $style = 'class="partialcorrect"';
                    }
                } else {
                    $style = '';
                }
            }

            // Print the input control
            switch ($wrapped->qtype) {
                case 'shortanswer':
                case 'numerical':
                    echo " <input $style $readonly $popup name=\"$inputname\"
                            type=\"text\" value=\"$response\" size=\"12\" /> ";
                    break;
                case 'multichoice':
                    $outputoptions = '<option></option>'; // Default empty option
                    foreach ($answers as $mcanswer) {
                        $selected = $response == $mcanswer->id
                                ? ' selected="selected" ' : '';
                        $outputoptions .= "<option value=\"$mcanswer->id\" $selected>$mcanswer->answer</option>";
                    }
                   echo "<select $popup $readonly $style name=\"$inputname\">";
                   echo $outputoptions;
                   echo '</select>';
                   break;
               default:
                   error("Unable to recognize questiontype ($wrapped->qtype) of
                          question part $positionkey.");
                   break;
           }
        }

        // Print the final piece of question text:
        echo $qtextremaining;
        $this->print_question_submit_buttons($question, $state, $cmoptions, $options);
    }

    function grade_responses(&$question, &$state, $cmoptions) {
        global $QTYPES;
        $teststate = clone($state);
        $state->raw_grade = 0;
        foreach($question->options->questions as $key => $wrapped) {
            $state->responses[$key] = html_entity_decode($state->responses[$key]);
            $teststate->responses = array('' => $state->responses[$key]);
            $teststate->raw_grade = 0;
            if (false === $QTYPES[$wrapped->qtype]
             ->grade_responses($wrapped, $teststate, $cmoptions)) {
                return false;
            }
            $state->raw_grade += $teststate->raw_grade;
        }
        $state->raw_grade /= $question->defaultgrade;
        $state->raw_grade = min(max((float) $state->raw_grade, 0.0), 1.0)
         * $question->maxgrade;

        if (empty($state->raw_grade)) {
            $state->raw_grade = 0.0;
        }
        $state->penalty = $question->penalty * $question->maxgrade;

        // mark the state as graded
        $state->event = ($state->event ==  QUESTION_EVENTCLOSE) ? QUESTION_EVENTCLOSEANDGRADE : QUESTION_EVENTGRADE;

        return true;
    }

    function get_actual_response($question, $state) {
        global $QTYPES;
        $teststate = clone($state);
        foreach($question->options->questions as $key => $wrapped) {
            $state->responses[$key] = html_entity_decode($state->responses[$key]);
            $teststate->responses = array('' => $state->responses[$key]);
            $correct = $QTYPES[$wrapped->qtype]
             ->get_actual_response($wrapped, $teststate);
            // change separator here if you want
            $responsesseparator = ',';
            $responses[$key] = implode($responsesseparator, $correct);
        }
        return $responses;
    }
    
/// BACKUP FUNCTIONS ////////////////////////////

    /*
     * Backup the data in the question
     *
     * This is used in question/backuplib.php
     */
    function backup($bf,$preferences,$question,$level=6) {

        $status = true;

        $multianswers = get_records("question_multianswer","question",$question,"id");
        //If there are multianswers
        if ($multianswers) {
            //Print multianswers header
            $status = fwrite ($bf,start_tag("MULTIANSWERS",$level,true));
            //Iterate over each multianswer
            foreach ($multianswers as $multianswer) {
                $status = fwrite ($bf,start_tag("MULTIANSWER",$level+1,true));
                //Print multianswer contents
                fwrite ($bf,full_tag("ID",$level+2,false,$multianswer->id));
                fwrite ($bf,full_tag("QUESTION",$level+2,false,$multianswer->question));
                fwrite ($bf,full_tag("SEQUENCE",$level+2,false,$multianswer->sequence));
                $status = fwrite ($bf,end_tag("MULTIANSWER",$level+1,true));
            }
            //Print multianswers footer
            $status = fwrite ($bf,end_tag("MULTIANSWERS",$level,true));
            //Now print question_answers
            $status = question_backup_answers($bf,$preferences,$question);
        }
        return $status;
    }

/// RESTORE FUNCTIONS /////////////////

    /*
     * Restores the data in the question
     *
     * This is used in question/restorelib.php
     */
    function restore($old_question_id,$new_question_id,$info,$restore) {

        $status = true;

        //Get the multianswers array
        $multianswers = $info['#']['MULTIANSWERS']['0']['#']['MULTIANSWER'];
        //Iterate over multianswers
        for($i = 0; $i < sizeof($multianswers); $i++) {
            $mul_info = $multianswers[$i];

            //We need this later
            $oldid = backup_todb($mul_info['#']['ID']['0']['#']);

            //Now, build the question_multianswer record structure
            $multianswer = new stdClass;
            $multianswer->question = $new_question_id;
            $multianswer->sequence = backup_todb($mul_info['#']['SEQUENCE']['0']['#']);

            //We have to recode the sequence field (a list of question ids)
            //Extracts question id from sequence
            $sequence_field = "";
            $in_first = true;
            $tok = strtok($multianswer->sequence,",");
            while ($tok) {
                //Get the answer from backup_ids
                $question = backup_getid($restore->backup_unique_code,"question",$tok);
                if ($question) {
                    if ($in_first) {
                        $sequence_field .= $question->new_id;
                        $in_first = false;
                    } else {
                        $sequence_field .= ",".$question->new_id;
                    }
                }
                //check for next
                $tok = strtok(",");
            }
            //We have the answers field recoded to its new ids
            $multianswer->sequence = $sequence_field;
            //The structure is equal to the db, so insert the question_multianswer
            $newid = insert_record("question_multianswer", $multianswer);

            //Save ids in backup_ids
            if ($newid) {
                backup_putid($restore->backup_unique_code,"question_multianswer",
                             $oldid, $newid);
            }

            //Do some output
            if (($i+1) % 50 == 0) {
                if (!defined('RESTORE_SILENTLY')) {
                    echo ".";
                    if (($i+1) % 1000 == 0) {
                        echo "<br />";
                    }
                }
                backup_flush(300);
            }
        }

        return $status;
    }

    function restore_map($old_question_id,$new_question_id,$info,$restore) {

        $status = true;

        //Get the multianswers array
        $multianswers = $info['#']['MULTIANSWERS']['0']['#']['MULTIANSWER'];
        //Iterate over multianswers
        for($i = 0; $i < sizeof($multianswers); $i++) {
            $mul_info = $multianswers[$i];

            //We need this later
            $oldid = backup_todb($mul_info['#']['ID']['0']['#']);

            //Now, build the question_multianswer record structure
            $multianswer->question = $new_question_id;
            $multianswer->answers = backup_todb($mul_info['#']['ANSWERS']['0']['#']);
            $multianswer->positionkey = backup_todb($mul_info['#']['POSITIONKEY']['0']['#']);
            $multianswer->answertype = backup_todb($mul_info['#']['ANSWERTYPE']['0']['#']);
            $multianswer->norm = backup_todb($mul_info['#']['NORM']['0']['#']);

            //If we are in this method is because the question exists in DB, so its
            //multianswer must exist too.
            //Now, we are going to look for that multianswer in DB and to create the
            //mappings in backup_ids to use them later where restoring states (user level).

            //Get the multianswer from DB (by question and positionkey)
            $db_multianswer = get_record ("question_multianswer","question",$new_question_id,
                                                      "positionkey",$multianswer->positionkey);
            //Do some output
            if (($i+1) % 50 == 0) {
                if (!defined('RESTORE_SILENTLY')) {
                    echo ".";
                    if (($i+1) % 1000 == 0) {
                        echo "<br />";
                    }
                }
                backup_flush(300);
            }

            //We have the database multianswer, so update backup_ids
            if ($db_multianswer) {
                //We have the newid, update backup_ids
                backup_putid($restore->backup_unique_code,"question_multianswer",$oldid,
                             $db_multianswer->id);
            } else {
                $status = false;
            }
        }

        return $status;
    }

    function restore_recode_answer($state, $restore) {
        //The answer is a comma separated list of hypen separated sequence number and answers. We may have to recode the answers
        $answer_field = "";
        $in_first = true;
        $tok = strtok($state->answer,",");
        while ($tok) {
            //Extract the multianswer_id and the answer
            $exploded = explode("-",$tok);
            $seqnum = $exploded[0];
            $answer = $exploded[1];
            // $sequence is an ordered array of the question ids.
            if (!$sequence = get_field('question_multianswer', 'sequence', 'question', $state->question)) {
                error("The cloze question $state->question is missing its options");
            }
            $sequence = explode(',', $sequence);
            // The id of the current question.
            $wrappedquestionid = $sequence[$seqnum-1];
            // now we can find the question
            if (!$wrappedquestion = get_record('question', 'id', $wrappedquestionid)) {
                notify("Can't find the subquestion $wrappedquestionid that is used as part $seqnum in cloze question $state->question");
            }
            // For multichoice question we need to recode the answer
            if ($answer and $wrappedquestion->qtype == 'multichoice') {
                //The answer is an answer_id, look for it in backup_ids
                if (!$ans = backup_getid($restore->backup_unique_code,"question_answers",$answer)) {
                    echo 'Could not recode cloze multichoice answer '.$answer.'<br />';
                }
                $answer = $ans->new_id;
            }
            //build the new answer field for each pair
            if ($in_first) {
                $answer_field .= $seqnum."-".$answer;
                $in_first = false;
            } else {
                $answer_field .= ",".$seqnum."-".$answer;
            }
            //check for next
            $tok = strtok(",");
        }
        return $answer_field;
    }


}
//// END OF CLASS ////


//////////////////////////////////////////////////////////////////////////
//// INITIATION - Without this line the question type is not in use... ///
//////////////////////////////////////////////////////////////////////////
$QTYPES['multianswer']= new embedded_cloze_qtype();
// The following adds the questiontype to the menu of types shown to teachers
$QTYPE_MENU['multianswer'] = get_string("multianswer", "quiz");

/////////////////////////////////////////////////////////////
//// ADDITIONAL FUNCTIONS
//// The functions below deal exclusivly with editing
//// of questions with question type 'multianswer'.
//// Therefore they are kept in this file.
//// They are not in the class as they are not
//// likely to be subject for overriding.
/////////////////////////////////////////////////////////////

// ANSWER_ALTERNATIVE regexes
define("ANSWER_ALTERNATIVE_FRACTION_REGEX",
       '=|%(-?[0-9]+)%');
// for the syntax '(?<!' see http://www.perl.com/doc/manual/html/pod/perlre.html#item_C
define("ANSWER_ALTERNATIVE_ANSWER_REGEX",
        '.+?(?<!\\\\|&)(?=[~#}]|$)');
        //'[^~#}]+');
define("ANSWER_ALTERNATIVE_FEEDBACK_REGEX",
        '.*?(?<!\\\\)(?=[~}]|$)');
        //'[//^~}]*');
define("ANSWER_ALTERNATIVE_REGEX",
       '(' . ANSWER_ALTERNATIVE_FRACTION_REGEX .')?'
       . '(' . ANSWER_ALTERNATIVE_ANSWER_REGEX . ')'
       . '(#(' . ANSWER_ALTERNATIVE_FEEDBACK_REGEX .'))?');

// Parenthesis positions for ANSWER_ALTERNATIVE_REGEX
define("ANSWER_ALTERNATIVE_REGEX_PERCENTILE_FRACTION", 2);
define("ANSWER_ALTERNATIVE_REGEX_FRACTION", 1);
define("ANSWER_ALTERNATIVE_REGEX_ANSWER", 3);
define("ANSWER_ALTERNATIVE_REGEX_FEEDBACK", 5);

// NUMBER_FORMATED_ALTERNATIVE_ANSWER_REGEX is used
// for identifying numerical answers in ANSWER_ALTERNATIVE_REGEX_ANSWER
define("NUMBER_REGEX",
        '-?(([0-9]+[.,]?[0-9]*|[.,][0-9]+)([eE][-+]?[0-9]+)?)');
define("NUMERICAL_ALTERNATIVE_REGEX",
        '^(' . NUMBER_REGEX . ')(:' . NUMBER_REGEX . ')?$');

// Parenthesis positions for NUMERICAL_FORMATED_ALTERNATIVE_ANSWER_REGEX
define("NUMERICAL_CORRECT_ANSWER", 1);
define("NUMERICAL_ABS_ERROR_MARGIN", 6);

// Remaining ANSWER regexes
define("ANSWER_TYPE_DEF_REGEX",
       '(NUMERICAL|NM)|(MULTICHOICE|MC)|(SHORTANSWER|SA|MW)');
define("ANSWER_START_REGEX",
       '\{([0-9]*):(' . ANSWER_TYPE_DEF_REGEX . '):');

define("ANSWER_REGEX",
        ANSWER_START_REGEX
        . '(' . ANSWER_ALTERNATIVE_REGEX
        . '(~'
        . ANSWER_ALTERNATIVE_REGEX
        . ')*)\}' );

// Parenthesis positions for singulars in ANSWER_REGEX
define("ANSWER_REGEX_NORM", 1);
define("ANSWER_REGEX_ANSWER_TYPE_NUMERICAL", 3);
define("ANSWER_REGEX_ANSWER_TYPE_MULTICHOICE", 4);
define("ANSWER_REGEX_ANSWER_TYPE_SHORTANSWER", 5);
define("ANSWER_REGEX_ALTERNATIVES", 6);

function qtype_multianswer_extract_question($text) {

////////////////////////////////////////////////
//// Define some constants first. It is not the
//// pattern commonly used in questiontypes.
//// The reason is that it has been moved here from
//// question/format/multianswer/format.php
////////////////////////////////////////////////


    // Undo the automatic addslashes, because we want to analyze the text - we need to remember this later and addslashes again!
    $text = stripslashes($text);

    // We need to allow entities (e.g. &#1085;) in answers. This is difficulty,
    // because the '#' character is used as delimiter between answer and
    // feedback as well as inside entities. The HTML editor automatically
    // replaces '&' with '&amp;', so we undo this to get back the entities we
    // originally wanted. However, this code leaves all &amp; alone, if they
    // are not followed by 2 to 9 characters and a final semicolon. This allows
    // to have an answer end on '&' with the feedback (e.g. answer&amp;#feedback).
    // When the plain text editor is used, the &amp; needs to be typed out
    // explicitly in this case.
    $text = preg_replace('/&amp;(#[0-9a-fx]{2,6}?);/', '&$1;', $text);

    // REGULAR EXPRESSION CONSTANTS
    // I do not know any way to make this easier
    // Regexes are always awkard when defined but more comprehensible
    // when used as constants in the executive code

    // Handle the entity encoded ampersand in entities (e.g. &amp;lt; -> &lt;)
    $text = preg_replace('/&amp;(.{2,9}?;)/', '&${1}', $text);
    $text = stripslashes($text);

////////////////////////////////////////
//// Start of the actual function
////////////////////////////////////////

    $question = new stdClass;
    $question->qtype = 'multianswer';
    $question->questiontext = $text;
    $question->options->questions = array();
    $question->defaultgrade = 0; // Will be increased for each answer norm

    for ($positionkey=1
        ; preg_match('/'.ANSWER_REGEX.'/', $question->questiontext, $answerregs)
        ; ++$positionkey ) {
        $wrapped = new stdClass;
        $wrapped->defaultgrade = $answerregs[ANSWER_REGEX_NORM]
            or $wrapped->defaultgrade = '1';
        if (!empty($answerregs[ANSWER_REGEX_ANSWER_TYPE_NUMERICAL])) {
            $wrapped->qtype = 'numerical';
            $wrapped->multiplier = array();
            $wrapped->units      = array();
        } else if(!empty($answerregs[ANSWER_REGEX_ANSWER_TYPE_SHORTANSWER])) {
            $wrapped->qtype = 'shortanswer';
            $wrapped->usecase = 0;
        } else if(!empty($answerregs[ANSWER_REGEX_ANSWER_TYPE_MULTICHOICE])) {
            $wrapped->qtype = 'multichoice';
            $wrapped->single = 1;
        } else {
            error("Cannot identify qtype $answerregs[2]");
            return false;
        }

        // Each $wrapped simulates a $form that can be processed by the
        // respective save_question and save_question_options methods of the
        // wrapped questiontypes
        $wrapped->answer   = array();
        $wrapped->fraction = array();
        $wrapped->feedback = array();
        $wrapped->shuffleanswers = 1;
        $wrapped->questiontext = addslashes($answerregs[0]); // here we don't want multianswer_escape, because this is editing time information
        $wrapped->questiontextformat = 0;

        $remainingalts = $answerregs[ANSWER_REGEX_ALTERNATIVES];
        while (preg_match('/~?'.ANSWER_ALTERNATIVE_REGEX.'/', $remainingalts, $altregs)) {
            if ('=' == $altregs[ANSWER_ALTERNATIVE_REGEX_FRACTION]) {
                $wrapped->fraction[] = '1';
            } else if ($percentile =
             $altregs[ANSWER_ALTERNATIVE_REGEX_PERCENTILE_FRACTION]){
                $wrapped->fraction[] = .01 * $percentile;
            } else {
                $wrapped->fraction[] = '0';
            }
            $wrapped->feedback[] = multianswer_escape(
             isset($altregs[ANSWER_ALTERNATIVE_REGEX_FEEDBACK])
             ? $altregs[ANSWER_ALTERNATIVE_REGEX_FEEDBACK] : '');
            if (!empty($answerregs[ANSWER_REGEX_ANSWER_TYPE_NUMERICAL])
                    && ereg(NUMERICAL_ALTERNATIVE_REGEX,
                            $altregs[ANSWER_ALTERNATIVE_REGEX_ANSWER],
                            $numregs) )
            {
                $wrapped->answer[] =
                 multianswer_escape($numregs[NUMERICAL_CORRECT_ANSWER]);
                if ($numregs[NUMERICAL_ABS_ERROR_MARGIN]) {
                    $wrapped->tolerance[] =
                     $numregs[NUMERICAL_ABS_ERROR_MARGIN];
                } else {
                    $wrapped->tolerance[] = 0;
                }
            } else { // Tolerance can stay undefined for non numerical questions
                $wrapped->answer[] = multianswer_escape(
                 $altregs[ANSWER_ALTERNATIVE_REGEX_ANSWER]);
            }
            $tmp = explode($altregs[0], $remainingalts, 2);
            $remainingalts = $tmp[1];
        }

        $question->defaultgrade += $wrapped->defaultgrade;
        $question->options->questions[$positionkey] = clone($wrapped);
        $question->questiontext = implode("{#$positionkey}",
                    explode($answerregs[0], $question->questiontext, 2));
    }
    $question->questiontext = multianswer_escape($question->questiontext);
    return $question;
}

function multianswer_escape($text) {
    $text = str_replace("&amp;", "&", $text);
    $text = str_replace('\#', '#', $text);
    $text = html_entity_decode($text);
    return addslashes($text);
}

?>