remove_taxonomy_slug_from_link.php

<?php

/* block remove "product_cat" from product category URL */
function filter_term_link( $termlink, $term, $taxonomy ) {
    if ( 'product_cat' != $taxonomy ) {
        return $termlink;
    }

    $termlink = str_replace( '/product_category/', '/', $termlink );

    return $termlink;
};
add_filter( 'term_link', 'filter_term_link', 10, 3 );
/* end of block */

/* Fix request when removed products_cat slug */
add_filter('request', function( $vars ) {
	global $wpdb;
	if( !empty( $vars['pagename'] ) || !empty( $vars['category_name'] ) || !empty( $vars['name'] ) || !empty( $vars['attachment'] ) ) {
		$slug = !empty( $vars['pagename'] ) ? $vars['pagename'] : ( ! empty( $vars['name'] ) ? $vars['name'] : ( !empty( $vars['category_name'] ) ? $vars['category_name'] : $vars['attachment'] ) );
		$exists = $wpdb->get_var( $wpdb->prepare( "SELECT t.term_id FROM $wpdb->terms t LEFT JOIN $wpdb->term_taxonomy tt ON tt.term_id = t.term_id WHERE tt.taxonomy = 'product_cat' AND t.slug = %s" ,array( $slug )));
		if( $exists ){
			$old_vars = $vars;
			$vars = array('product_cat' => $slug );
			if ( !empty( $old_vars['paged'] ) || !empty( $old_vars['page'] ) )
				$vars['paged'] = ! empty( $old_vars['paged'] ) ? $old_vars['paged'] : $old_vars['page'];
		}
	}
	return $vars;
});
/* end of block */

/* block remove "product" from product URL */
function custom_remove_cpt_slug( $post_link, $post, $leavename ) {

    if ( 'product' != $post->post_type || 'publish' != $post->post_status ) {
        return $post_link;
    }

    $post_link = str_replace( '/product/', '/', $post_link );

    return $post_link;
}
add_filter( 'post_type_link', 'custom_remove_cpt_slug', 10, 3 );

function custom_parse_request_tricksy( $query ) {

    // Only noop the main query
    if ( ! $query->is_main_query() )
        return;

    // Only noop our very specific rewrite rule match
    if ( 2 != count( $query->query ) || ! isset( $query->query['page'] ) ) {
        return;
    }

    global $wp_query;

    // 'name' will be set if post permalinks are just post_name, otherwise the page rule will match
    if ( ! empty( $query->query['name'] ) ) {
        $query->set( 'post_type', array( 'post', 'product', 'page' ) );
    }
}
add_action( 'pre_get_posts', 'custom_parse_request_tricksy' );
/* end of block */