'use strict';

exports.type = 'perItemReverse';

exports.active = true;

exports.description = 'removes empty container elements';

var container = require('./_collections').elemsGroups.container;

/**
 * Remove empty containers.
 *
 * @see https://www.w3.org/TR/SVG11/intro.html#TermContainerElement
 *
 * @example
 * <defs/>
 *
 * @example
 * <g><marker><a/></marker></g>
 *
 * @param {Object} item current iteration item
 * @return {Boolean} if false, item will be filtered out
 *
 * @author Kir Belevich
 */
exports.fn = function(item) {
  return (
    item.isElem(container) === false ||
    item.isEmpty() === false ||
    item.isElem('svg') ||
    (item.isElem('pattern') && item.hasAttrLocal('href')) ||
    // The 'g' may not have content, but the filter may cause a rectangle
    // to be created and filled with pattern.
    (item.isElem('g') && item.hasAttr('filter')) ||
    // empty <mask> hides masked element
    (item.isElem('mask') && item.hasAttr('id'))
  );
};