magento2/app/code/Magento/LayeredNavigation/Block/Navigation/State.php

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\LayeredNavigation\Block\Navigation;

use Magento\Framework\View\Element\Template;

/**
 * Layered navigation state
 *
 * @api
 * @since 100.0.2
 */
class State extends \Magento\Framework\View\Element\Template
{
    /**
     * @var string
     */
    protected $_template = 'Magento_LayeredNavigation::layer/state.phtml';

    /**
     * Catalog layer
     *
     * @var \Magento\Catalog\Model\Layer
     */
    protected $_catalogLayer;

    /**
     * @param \Magento\Framework\View\Element\Template\Context $context
     * @param \Magento\Catalog\Model\Layer\Resolver $layerResolver
     * @param array $data
     */
    public function __construct(
        \Magento\Framework\View\Element\Template\Context $context,
        \Magento\Catalog\Model\Layer\Resolver $layerResolver,
        array $data = []
    ) {
        $this->_catalogLayer = $layerResolver->get();
        parent::__construct($context, $data);
    }

    /**
     * Retrieve active filters
     *
     * @return array
     */
    public function getActiveFilters()
    {
        $filters = $this->getLayer()->getState()->getFilters();
        if (!is_array($filters)) {
            $filters = [];
        }
        return $filters;
    }

    /**
     * Retrieve Clear Filters URL
     *
     * @return string
     */
    public function getClearUrl()
    {
        $filterState = [];
        foreach ($this->getActiveFilters() as $item) {
            $filterState[$item->getFilter()->getRequestVar()] = $item->getFilter()->getCleanValue();
        }
        $params['_current'] = true;
        $params['_use_rewrite'] = true;
        $params['_query'] = $filterState;
        $params['_escape'] = true;
        return $this->_urlBuilder->getUrl('*/*/*', $params);
    }

    /**
     * Retrieve Layer object
     *
     * @return \Magento\Catalog\Model\Layer
     */
    public function getLayer()
    {
        if (!$this->hasData('layer')) {
            $this->setLayer($this->_catalogLayer);
        }
        return $this->_getData('layer');
    }
}