LinearNavigator.php

Go to the documentation of this file.

<?php
 
declare(strict_types=1);
 
namespace ILIAS\LearningSequence\Player;
 
class LinearNavigator implements LSNavigator
{
    public function getSuccessors(array $items, \LSLearnerItem $current): array
    {
        $position = $this->findPosition($items, $current);
        $next = $position + 1;
        if ($next >= 0 && $next < count($items)) {
            return [$items[$next]];
        }
        return [];
    }
 
    public function getStructuralSuccessors(array $items, \LSItem $current): array
    {
        $position = $this->findPosition($items, $current);
        $next = $position + 1;
        if ($next >= 0 && $next < count($items)) {
            return [$items[$next]];
        }
        return [];
    }
 
    public function getPredecessors(array $items, \LSLearnerItem $current): array
    {
        $position = $this->findPosition($items, $current);
        $previous = $position - 1;
        if ($previous >= 0 && $previous < count($items)) {
            return [$items[$previous]];
        }
        return [];
    }
 
    public function canLeave(\LSLearnerItem $current): bool
    {
        return true;
    }
 
    public function canEnter(\LSLearnerItem $target): bool
    {
        return true;
    }
 
    public function canEnterIgnoringEdges(\LSLearnerItem $target): bool
    {
        return true;
    }
 
    public function canEnterFrom(\LSLearnerItem $current, \LSLearnerItem $target): bool
    {
        return true;
    }
 
    public function preload(array $items): void
    {
    }
 
    public function getInputConditionIds(\LSLearnerItem $item): array
    {
        return [];
    }
 
    public function getOutputConditionIds(\LSLearnerItem $item): array
    {
        return [];
    }
 
    protected function findPosition(array $items, \LSItem $item): int
    {
        foreach ($items as $index => $candidate) {
            if ($candidate->getRefId() === $item->getRefId()) {
                return $index;
            }
        }
        throw new \Exception("This is not a valid item.", 1);
    }
}