Sample Eight Day Week filters for the Observer

eight-day-week-filters.php

<?php

add_filter( 'Eight_Day_Week\Plugins\Article_Export\xml_outer_elements', function( $elements, $article ) {
	$elements['subHeadline'] = get_post_meta( $article->ID, 'nyo_dek', true );
	return $elements;
}, 10, 2 );

add_filter( 'Eight_Day_Week\Plugins\Article_Export\xml_outer_elements', function( $elements, $article ) {
	if( function_exists( '\Eight_Day_Week\Plugins\Article_Byline\get_article_byline' ) ) {
		$elements['byline']      = \Eight_Day_Week\Plugins\Article_Byline\get_article_byline( $article );
	}
	return $elements;
}, 10, 2 );

add_filter( 'Eight_Day_Week\Plugins\Article_Export\xpath_extract', function( $extract ) {
	$extract[] = [
		'tag_name'  => 'pullQuote',
		'container' => 'pullQuotes',
		'query'     => '//p[contains(@class, "pullquote")]'
	];
	return $extract;
} );

add_filter( 'Eight_Day_Week\Plugins\Article_Export\dom', function ( $dom ) {
	$swap_tag_name = 'emphasized';

	$extract_map = [
		'strong' => [
			'solo'  => 'bold',
			'inner' => 'em'
		],
		'em'     => [
			'solo'  => 'italics',
			'inner' => 'strong'
		],
	];

	foreach ( $extract_map as $tag_name => $map ) {
		$nodes  = $dom->getElementsByTagName( $tag_name );
		$length = $nodes->length;

		for ( $i = $length; -- $i >= 0; ) {
			$el         = $nodes->item( $i );
			$emphasized = $el->getElementsByTagName( $map['inner'] );
			if ( $emphasized->length ) {
				$em            = $dom->createElement( $swap_tag_name );
				$em->nodeValue = $el->nodeValue;
				try {
					$el->parentNode->replaceChild( $em, $el );
				} catch ( \Exception $e ) {

				}
				continue;
			}

			$new            = $dom->createElement( $map['solo'] );
			$new->nodeValue = $el->nodeValue;
			try {
				$el->parentNode->replaceChild( $new, $el );
			} catch ( \Exception $e ) {

			}

		}

	}

	return $dom;

} );