WordPress function to create a breadcrumb nav.

wp-breadcrumbs-helpers.php

<?php


/**
 * Wrap the crumb.
 * @see https://schema.org/breadcrumb
 */
if( ! function_exists( 'anchorage_get_breadcrumb' ) ) {
	function anchorage_get_breadcrumb( $crumb_title, $crumb_link ) {

		$crumb_title = wp_kses_post( $crumb_title );
		$crumb_link = esc_url( $crumb_link );

		$out = "<span itemprop='title'>$crumb_title</span>";
			
		// Unless it's a crumb to the current page, link it.
		if( ! empty( $crumb_link ) ) {
			$out = "<a href='$crumb_link' class='breadcrumbs-link' itemprop='url'>$out</a>";
		}

		return $out;

	}
}

/**
 * Determine if a post type supports a taxonomy.
 *
 * @param  string $post_type The name of a post type.
 * @return  boolean Returns true if the given post type supports the given taxonomy, else false.
 */
if( ! function_exists( 'anchorage_post_type_has_tax' ) ) {
	function anchorage_post_type_has_tax( $post_type, $taxonomy_name ) {
		
		if( ( $post_type == 'post' ) && ( ( $taxonomy_name == 'post_tag' ) || ( $taxonomy_name == 'category' ) ) ) { return true; }
		

		$post_type_object = get_post_type_object( $post_type );
		$taxonomies = $post_type_object -> taxonomies;
		if( empty( $taxonomies ) ) { return false; }
		if( in_array( $taxonomy_name, $taxonomies ) ) {
			return true;
		}
		return false;
	}
}

/**
 * Determine if a post type is custom or not.
 * 
 * @param  string $post_type The name of a post type.
 * @return  boolean Returns true if the given post type is custom, else false.
 */
if( ! function_exists( 'anchorage_is_custom_post_type' ) ) {
	function anchorage_is_custom_post_type( $post_type ) {

	    $all_custom_post_types = get_post_types( array ( '_builtin' => FALSE ) );

	    // there are no custom post types
	    if ( empty ( $all_custom_post_types ) ) {
	        return false;
	    }

	    $custom_types = array_keys( $all_custom_post_types );
	    
	    if( in_array( $post_type, $custom_types ) ) {
	    	return true;
	    } 
	    return false;
	}
}

/**
 * Determine if the current view is tax, tag, or cat.
 *
 * @return boolean Returns true if current view is tax, tag, or cat, otherwise false.
 */
if( ! function_exists( 'anchorage_is_termish' ) ) {
	function anchorage_is_termish() {
		if( is_tax() ||  is_tag() || is_category() ) {
			return true;
		}
		return false;
	}
}

/**
 * Determine if the current view is single, singular, or page.
 *
 * @return boolean Returns true if is single, singular, or page, otherwise false.
 */
if( ! function_exists( 'anchorage_is_singlish' ) ) {
	function anchorage_is_singlish() {
		if( is_single() || is_singular() || is_page() ) {
			return true;
		}
		return false;
	}
}

/**
 * Get an HTML <hr /> with classes expected by our stylesheet.
 *
 * @param array $classes An array of HTML classes.
 * @return  string An HTML <hr /> with classes expected by our stylesheet.
 *
 * @since  anchorage 1.0
 */
if( ! function_exists( 'anchorage_get_hard_rule' ) ) {
	function anchorage_get_hard_rule( $classes = array() ) {
		
		$classes     = array_map( 'sanitize_html_class', $classes );
		$classes   []= 'break';
		$classes_str = implode( ' ', $classes );
		
		$out = "<hr class='$classes_str' />";
		return $out;
	}
}


/**
 * Grab the unicode char for an arrow in a given direction, with classes and an href.
 * 
 * @param  string $direction The direction in which the arrow will point.
 * @param  array  $classes   An array of HTML classes for the arrow.
 * @param  string $href      Link the arrow to a url.
 * @return string The arrow, with classes, wrapped in either a link or span.
 *
 * @since  anchorage 1.0
 */
if( ! function_exists( 'anchorage_get_arrow' ) ) {
	function anchorage_get_arrow( $direction = 'down', $classes = array(), $href = '#' ) {

		// Grab the correct arrow char for the direction.
		if ( $direction == 'left' ) {
			$out = esc_html__( '&larr;', 'anchorage' );
		} elseif ( $direction == 'up' ) {
			$out = esc_html__( '&uarr;', 'anchorage' );
		} elseif ( $direction == 'right' ) {
			$out = esc_html__( '&rarr;', 'anchorage' );
		} else {
			$out = esc_html__( '&darr;', 'anchorage' );
		}

		// Build the classes.
		$classes = array_map( 'sanitize_html_class', $classes );
		$classes = implode( ' ', $classes );
		$classes = " class='$classes arrow' ";

		$out = " $out ";

		// If there's an href, wrap the arrow in a link.
		$href = esc_attr( $href );
		if( ! empty( $href ) ) {
			$out = "<a href='$href' $classes>$out</a>";
		
		// Else, if there are classes, wrap it in a span.
		} elseif( ! empty( $classes ) ) {
			$out = "<span $classes>$out</span>";
		}
		
		return $out;
	}
}