Dan Marsden
123 lines
4.6 KiB
PHP
123 lines
4.6 KiB
PHP
<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* This is really a little language parser for AICC_SCRIPT
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* evaluates the expression and returns a boolean answer
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* see 2.3.2.5.1. Sequencing/Navigation Today - from the SCORM 1.2 spec (CAM).
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*
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* @param string $prerequisites the aicc_script prerequisites expression
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* @param array $usertracks the tracked user data of each SCO visited
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* @return boolean
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*/
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function scorm_eval_prerequisites($prerequisites, $usertracks) {
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// this is really a little language parser - AICC_SCRIPT is the reference
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// see 2.3.2.5.1. Sequencing/Navigation Today - from the SCORM 1.2 spec
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$element = '';
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$stack = array();
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$statuses = array(
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'passed' => 'passed',
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'completed' => 'completed',
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'failed' => 'failed',
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'incomplete' => 'incomplete',
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'browsed' => 'browsed',
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'not attempted' => 'notattempted',
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'p' => 'passed',
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'c' => 'completed',
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'f' => 'failed',
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'i' => 'incomplete',
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'b' => 'browsed',
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'n' => 'notattempted'
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);
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$i=0;
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// expand the amp entities
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$prerequisites = preg_replace('/&/', '&', $prerequisites);
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// find all my parsable tokens
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$prerequisites = preg_replace('/(&|\||\(|\)|\~)/', '\t$1\t', $prerequisites);
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// expand operators
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$prerequisites = preg_replace('/&/', '&&', $prerequisites);
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$prerequisites = preg_replace('/\|/', '||', $prerequisites);
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// now - grab all the tokens
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$elements = explode('\t', trim($prerequisites));
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// process each token to build an expression to be evaluated
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$stack = array();
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foreach ($elements as $element) {
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$element = trim($element);
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if (empty($element)) {
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continue;
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}
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if (!preg_match('/^(&&|\|\||\(|\))$/', $element)) {
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// create each individual expression
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// search for ~ = <> X*{}
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// sets like 3*{S34, S36, S37, S39}
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if (preg_match('/^(\d+)\*\{(.+)\}$/', $element, $matches)) {
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$repeat = $matches[1];
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$set = explode(',', $matches[2]);
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$count = 0;
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foreach ($set as $setelement) {
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if (isset($usertracks[$setelement]) &&
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($usertracks[$setelement]->status == 'completed' || $usertracks[$setelement]->status == 'passed')) {
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$count++;
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}
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}
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if ($count >= $repeat) {
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$element = 'true';
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} else {
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$element = 'false';
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}
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// ~ Not
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} else if ($element == '~') {
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$element = '!';
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// = | <>
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} else if (preg_match('/^(.+)(\=|\<\>)(.+)$/', $element, $matches)) {
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$element = trim($matches[1]);
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if (isset($usertracks[$element])) {
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$value = trim(preg_replace('/(\'|\")/', '', $matches[3]));
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if (isset($statuses[$value])) {
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$value = $statuses[$value];
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}
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if ($matches[2] == '<>') {
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$oper = '!=';
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} else {
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$oper = '==';
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}
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$element = '(\''.$usertracks[$element]->status.'\' '.$oper.' \''.$value.'\')';
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} else {
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$element = 'false';
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}
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// everything else must be an element defined like S45 ...
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} else {
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if (isset($usertracks[$element]) &&
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($usertracks[$element]->status == 'completed' || $usertracks[$element]->status == 'passed')) {
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$element = 'true';
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} else {
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$element = 'false';
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}
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}
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}
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$stack []= ' '.$element.' ';
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}
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return eval('return '.implode($stack).';');
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}
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