WordPress/wp-includes/category-template.php

<?php

function get_category_children( $id, $before = '/', $after = '', $visited = array() ) {
	if ( 0 == $id )
		return '';

	$chain = '';
	// TODO: consult hierarchy
	$cat_ids = get_all_category_ids();
	foreach ( (array) $cat_ids as $cat_id ) {
		if ( $cat_id == $id )
			continue;

		$category = get_category( $cat_id );
		if ( is_wp_error( $category ) )
			return $category;
		if ( $category->parent == $id && !in_array( $category->term_id, $visited ) ) {
			$visited[] = $category->term_id;
			$chain .= $before.$category->term_id.$after;
			$chain .= get_category_children( $category->term_id, $before, $after );
		}
	}
	return $chain;
}

function get_category_link( $category_id ) {
	global $wp_rewrite;
	$catlink = $wp_rewrite->get_category_permastruct();

	if ( empty( $catlink ) ) {
		$file = get_option( 'home' ) . '/';
		$catlink = $file . '?cat=' . $category_id;
	} else {
		$category = &get_category( $category_id );
		if ( is_wp_error( $category ) )
			return $category;
		$category_nicename = $category->slug;

		if ( $parent = $category->parent )
			$category_nicename = get_category_parents( $parent, false, '/', true ) . $category_nicename;

		$catlink = str_replace( '%category%', $category_nicename, $catlink );
		$catlink = get_option( 'home' ) . user_trailingslashit( $catlink, 'category' );
	}
	return apply_filters( 'category_link', $catlink, $category_id );
}

function get_category_parents( $id, $link = FALSE, $separator = '/', $nicename = FALSE, $visited = array() ) {
	$chain = '';
	$parent = &get_category( $id );
	if ( is_wp_error( $parent ) )
		return $parent;

	if ( $nicename )
		$name = $parent->slug;
	else
		$name = $parent->cat_name;

	if ( $parent->parent && ( $parent->parent != $parent->term_id ) && !in_array( $parent->parent, $visited ) ) {
		$visited[] = $parent->parent;
		$chain .= get_category_parents( $parent->parent, $link, $separator, $nicename, $visited );
	}

	if ( $link )
		$chain .= '<a href="' . get_category_link( $parent->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $parent->cat_name ) . '">'.$name.'</a>' . $separator;
	else
		$chain .= $name.$separator;
	return $chain;
}

function get_the_category( $id = false ) {
	global $post;

	$id = (int) $id;
	if ( !$id )
		$id = (int) $post->ID;

	$categories = get_object_term_cache( $id, 'category' );
	if ( false === $categories )
		$categories = wp_get_object_terms( $id, 'category' );

	if ( !empty( $categories ) )
		usort( $categories, '_usort_terms_by_name' );
	else
		$categories = array();

	foreach ( (array) array_keys( $categories ) as $key ) {
		_make_cat_compat( $categories[$key] );
	}

	return $categories;
}

function _usort_terms_by_name( $a, $b ) {
	return strcmp( $a->name, $b->name );
}

function _usort_terms_by_ID( $a, $b ) {
	if ( $a->term_id > $b->term_id )
		return 1;
	elseif ( $a->term_id < $b->term_id )
		return -1;
	else
		return 0;
}

function get_the_category_by_ID( $cat_ID ) {
	$cat_ID = (int) $cat_ID;
	$category = &get_category( $cat_ID );
	if ( is_wp_error( $category ) )
		return $category;
	return $category->name;
}

function get_the_category_list( $separator = '', $parents='', $post_id = false ) {
	global $wp_rewrite;
	$categories = get_the_category( $post_id );
	if ( empty( $categories ) )
		return apply_filters( 'the_category', __( 'Uncategorized' ), $separator, $parents );

	$rel = ( is_object( $wp_rewrite ) && $wp_rewrite->using_permalinks() ) ? 'rel="category tag"' : 'rel="category"';

	$thelist = '';
	if ( '' == $separator ) {
		$thelist .= '<ul class="post-categories">';
		foreach ( $categories as $category ) {
			$thelist .= "\n\t<li>";
			switch ( strtolower( $parents ) ) {
				case 'multiple':
					if ( $category->parent )
						$thelist .= get_category_parents( $category->parent, TRUE );
					$thelist .= '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . $rel . '>' . $category->name.'</a></li>';
					break;
				case 'single':
					$thelist .= '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . $rel . '>';
					if ( $category->parent )
						$thelist .= get_category_parents( $category->parent, FALSE );
					$thelist .= $category->name.'</a></li>';
					break;
				case '':
				default:
					$thelist .= '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . $rel . '>' . $category->cat_name.'</a></li>';
			}
		}
		$thelist .= '</ul>';
	} else {
		$i = 0;
		foreach ( $categories as $category ) {
			if ( 0 < $i )
				$thelist .= $separator . ' ';
			switch ( strtolower( $parents ) ) {
				case 'multiple':
					if ( $category->parent )
						$thelist .= get_category_parents( $category->parent, TRUE );
					$thelist .= '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . $rel . '>' . $category->cat_name.'</a>';
					break;
				case 'single':
					$thelist .= '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . $rel . '>';
					if ( $category->parent )
						$thelist .= get_category_parents( $category->parent, FALSE );
					$thelist .= "$category->cat_name</a>";
					break;
				case '':
				default:
					$thelist .= '<a href="' . get_category_link( $category->term_id ) . '" title="' . sprintf( __( "View all posts in %s" ), $category->name ) . '" ' . $rel . '>' . $category->name.'</a>';
			}
			++$i;
		}
	}
	return apply_filters( 'the_category', $thelist, $separator, $parents );
}

/*
 * in_category() - Checks whether the current post is within a particular category
 *
 * This function checks to see if the post is within the supplied category.  The categoy
 * can be specified by number or name and will be checked as a name first to allow for categories with numeric names.
 * Note: Prior to v2.5 of WordPress category names where not supported.
 *
 * @since 1.2.0
 *
 * @param int|string $category
 * @return bool true if the post is in the supplied category
*/
function in_category( $category ) { // Check if the current post is in the given category
	global $post;

	if ( empty( $category ) )
		return false;

	// If category is not an int, check to see if it's a name
	if ( ! is_int( $category ) ) {
		$cat_ID = get_cat_ID( $category );
		if ( $cat_ID )
			$category = $cat_ID;
	}

	$categories = get_object_term_cache( $post->ID, 'category' );
	if ( false === $categories )
		$categories = wp_get_object_terms( $post->ID, 'category' );
	if ( array_key_exists( $category, $categories ) )
		return true;
	else
		return false;
}

function the_category( $separator = '', $parents='', $post_id = false ) {
	echo get_the_category_list( $separator, $parents, $post_id );
}

function category_description( $category = 0 ) {
	global $cat;
	if ( !$category )
		$category = $cat;

	return get_term_field( 'description', $category, 'category' );
}

function wp_dropdown_categories( $args = '' ) {
	$defaults = array(
		'show_option_all' => '', 'show_option_none' => '',
		'orderby' => 'ID', 'order' => 'ASC',
		'show_last_update' => 0, 'show_count' => 0,
		'hide_empty' => 1, 'child_of' => 0,
		'exclude' => '', 'echo' => 1,
		'selected' => 0, 'hierarchical' => 0,
		'name' => 'cat', 'class' => 'postform',
		'depth' => 0, 'tab_index' => 0
	);

	$defaults['selected'] = ( is_category() ) ? get_query_var( 'cat' ) : 0;

	$r = wp_parse_args( $args, $defaults );
	$r['include_last_update_time'] = $r['show_last_update'];
	extract( $r );

	$tab_index_attribute = '';
	if ( (int) $tab_index > 0 )
		$tab_index_attribute = " tabindex=\"$tab_index\"";

	$categories = get_categories( $r );

	$output = '';
	if ( ! empty( $categories ) ) {
		$output = "<select name='$name' id='$name' class='$class' $tab_index_attribute>\n";

		if ( $show_option_all ) {
			$show_option_all = apply_filters( 'list_cats', $show_option_all );
			$output .= "\t<option value='0'>$show_option_all</option>\n";
		}

		if ( $show_option_none ) {
			$show_option_none = apply_filters( 'list_cats', $show_option_none );
			$output .= "\t<option value='-1'>$show_option_none</option>\n";
		}

		if ( $hierarchical )
			$depth = $r['depth'];  // Walk the full depth.
		else
			$depth = -1; // Flat.

		$output .= walk_category_dropdown_tree( $categories, $depth, $r );
		$output .= "</select>\n";
	}

	$output = apply_filters( 'wp_dropdown_cats', $output );

	if ( $echo )
		echo $output;

	return $output;
}

function wp_list_categories( $args = '' ) {
	$defaults = array(
		'show_option_all' => '', 'orderby' => 'name',
		'order' => 'ASC', 'show_last_update' => 0,
		'style' => 'list', 'show_count' => 0,
		'hide_empty' => 1, 'use_desc_for_title' => 1,
		'child_of' => 0, 'feed' => '', 'feed_type' => '',
		'feed_image' => '', 'exclude' => '', 'current_category' => 0,
		'hierarchical' => true, 'title_li' => __( 'Categories' ),
		'echo' => 1, 'depth' => 0
	);

	$r = wp_parse_args( $args, $defaults );

	if ( !isset( $r['pad_counts'] ) && $r['show_count'] && $r['hierarchical'] ) {
		$r['pad_counts'] = true;
	}

	if ( isset( $r['show_date'] ) ) {
		$r['include_last_update_time'] = $r['show_date'];
	}

	extract( $r );

	$categories = get_categories( $r );

	$output = '';
	if ( $title_li && 'list' == $style )
			$output = '<li class="categories">' . $r['title_li'] . '<ul>';

	if ( empty( $categories ) ) {
		if ( 'list' == $style )
			$output .= '<li>' . __( "No categories" ) . '</li>';
		else
			$output .= __( "No categories" );
	} else {
		global $wp_query;

		if( !empty( $show_option_all ) )
			if ( 'list' == $style )
				$output .= '<li><a href="' .  get_bloginfo( 'url' )  . '">' . $show_option_all . '</a></li>';
			else
				$output .= '<a href="' .  get_bloginfo( 'url' )  . '">' . $show_option_all . '</a>';

		if ( empty( $r['current_category'] ) && is_category() )
			$r['current_category'] = $wp_query->get_queried_object_id();

		if ( $hierarchical )
			$depth = $r['depth'];
		else
			$depth = -1; // Flat.

		$output .= walk_category_tree( $categories, $depth, $r );
	}

	if ( $title_li && 'list' == $style )
		$output .= '</ul></li>';

	$output = apply_filters( 'wp_list_categories', $output );

	if ( $echo )
		echo $output;
	else
		return $output;
}

function wp_tag_cloud( $args = '' ) {
	$defaults = array(
		'smallest' => 8, 'largest' => 22, 'unit' => 'pt', 'number' => 45,
		'format' => 'flat', 'orderby' => 'name', 'order' => 'ASC',
		'exclude' => '', 'include' => ''
	);
	$args = wp_parse_args( $args, $defaults );

	$tags = get_tags( array_merge( $args, array( 'orderby' => 'count', 'order' => 'DESC' ) ) ); // Always query top tags

	if ( empty( $tags ) )
		return;

	foreach ( $tags as $key => $tag ) {
		$link = get_tag_link( $tag->term_id );
		if ( is_wp_error( $link ) )
			return false;

		$tags[ $key ]->link = $link;
		$tags[ $key ]->id = $tag->term_id;
	}

	$return = wp_generate_tag_cloud( $tags, $args ); // Here's where those top tags get sorted according to $args

	$return = apply_filters( 'wp_tag_cloud', $return, $args );

	if ( 'array' == $args['format'] )
		return $return;

	echo $return;
}

/**
 * Generates a tag cloud (heatmap) from provided data
 *
 * TODO: Complete
 *
 * @since 2.6
 *
 * $tags = array of objects with the properties 'name', 'link', 'id', and 'count'
 * $args['format'] = 'flat' => whitespace separated, 'list' => UL, 'array' => array()
 * $args['orderby'] = 'name', 'count'
*/
function wp_generate_tag_cloud( $tags, $args = '' ) {
	global $wp_rewrite;
	$defaults = array(
		'smallest' => 8, 'largest' => 22, 'unit' => 'pt',
		'format' => 'flat', 'orderby' => 'name', 'order' => 'ASC',
		'single_text' => '%d topic', 'multiple_text' => '%d topics'
	);
	$args = wp_parse_args( $args, $defaults );
	extract( $args );

	if ( empty( $tags ) )
		return;

	$counts = array();
	foreach ( (array) $tags as $key => $tag )
		$counts[ $key ] = $tag->count;

	$min_count = min( $counts );
	$spread = max( $counts ) - $min_count;
	if ( $spread <= 0 )
		$spread = 1;
	$font_spread = $largest - $smallest;
	if ( $font_spread <= 0 )
		$font_spread = 1;
	$font_step = $font_spread / $spread;

	// SQL cannot save you; this is a second (potentially different) sort on a subset of data.
	if ( 'name' == $orderby )
		uksort( $counts, 'strnatcasecmp' );
	else
		asort( $counts );

	if ( 'DESC' == $order )
		$counts = array_reverse( $counts, true );
	elseif ( 'RAND' == $order ) {
		$keys = array_rand( $counts, count( $counts ) );
		foreach ( $keys as $key )
			$temp[$key] = $counts[$key];
		$counts = $temp;
		unset( $temp );
	}

	$a = array();

	$rel = ( is_object( $wp_rewrite ) && $wp_rewrite->using_permalinks() ) ? ' rel="tag"' : '';

	foreach ( $counts as $key => $count ) {
		$tag_link = clean_url( $tags[ $key ]->link );
		$tag_id = $tags[ $key ]->id;
		$tag_name = $tags[ $key ]->name;
		$a[] = "<a href='$tag_link' class='tag-link-$tag_id' title='" . attribute_escape( sprintf( __ngettext( $single_text, $multiple_text, $count ), $count ) ) . "'$rel style='font-size: " .
			( $smallest + ( ( $count - $min_count ) * $font_step ) )
			. "$unit;'>$tag_name</a>";
	}

	switch ( $format ) :
	case 'array' :
		$return =& $a;
		break;
	case 'list' :
		$return = "<ul class='wp-tag-cloud'>\n\t<li>";
		$return .= join( "</li>\n\t<li>", $a );
		$return .= "</li>\n</ul>\n";
		break;
	default :
		$return = join( "\n", $a );
		break;
	endswitch;

	return apply_filters( 'wp_generate_tag_cloud', $return, $tags, $args );
}

//
// Helper functions
//

function walk_category_tree() {
	$walker = new Walker_Category;
	$args = func_get_args();
	return call_user_func_array(array( &$walker, 'walk' ), $args );
}

function walk_category_dropdown_tree() {
	$walker = new Walker_CategoryDropdown;
	$args = func_get_args();
	return call_user_func_array(array( &$walker, 'walk' ), $args );
}

//
// Tags
//

function get_tag_link( $tag_id ) {
	global $wp_rewrite;
	$taglink = $wp_rewrite->get_tag_permastruct();

	$tag = &get_term( $tag_id, 'post_tag' );
	if ( is_wp_error( $tag ) )
		return $tag;
	$slug = $tag->slug;

	if ( empty( $taglink ) ) {
		$file = get_option( 'home' ) . '/';
		$taglink = $file . '?tag=' . $slug;
	} else {
		$taglink = str_replace( '%tag%', $slug, $taglink );
		$taglink = get_option( 'home' ) . user_trailingslashit( $taglink, 'category' );
	}
	return apply_filters( 'tag_link', $taglink, $tag_id );
}

function get_the_tags( $id = 0 ) {
	return apply_filters( 'get_the_tags', get_the_terms( $id, 'post_tag' ) );
}

function get_the_tag_list( $before = '', $sep = '', $after = '' ) {
	return apply_filters( 'the_tags', get_the_term_list( 0, 'post_tag', $before, $sep, $after ) );
}

function the_tags( $before = 'Tags: ', $sep = ', ', $after = '' ) {
	return the_terms( 0, 'post_tag', $before, $sep, $after );
}

function get_the_terms( $id = 0, $taxonomy ) {
	global $post;

 	$id = (int) $id;

	if ( ! $id && ! in_the_loop() )
		return false; // in-the-loop function

	if ( !$id )
		$id = (int) $post->ID;

	$terms = get_object_term_cache( $id, $taxonomy );
	if ( false === $terms )
		$terms = wp_get_object_terms( $id, $taxonomy );

	if ( empty( $terms ) )
		return false;

	return $terms;
}

function get_the_term_list( $id = 0, $taxonomy, $before = '', $sep = '', $after = '' ) {
	$terms = get_the_terms( $id, $taxonomy );

	if ( is_wp_error( $terms ) )
		return $terms;

	if ( empty( $terms ) )
		return false;

	foreach ( $terms as $term ) {
		$link = get_term_link( $term, $taxonomy );
		if ( is_wp_error( $link ) )
			return $link;
		$term_links[] = '<a href="' . $link . '" rel="tag">' . $term->name . '</a>';
	}

	$term_links = apply_filters( "term_links-$taxonomy", $term_links );

	return $before . join( $sep, $term_links ) . $after;
}

function the_terms( $id, $taxonomy, $before = '', $sep = '', $after = '' ) {
	$return = get_the_term_list( $id, $taxonomy, $before, $sep, $after );
	if ( is_wp_error( $return ) )
		return false;
	else
		echo $return;
}

/**
 * Check if the current post has the given tag
 *
 * @package WordPress
 * @since 2.6
 *
 * @uses wp_get_object_terms() Gets the tags.
 *
 * @param string|int|array $tag Optional. The tag name/id/slug or array of them to check for
 * @return bool True if the current post has the given tag, or any tag, if no tag specified
 */
function has_tag( $tag = '' ) {
	global $post;
	$taxonomy = 'post_tag';

	if ( !in_the_loop() ) return false; // in-the-loop function

	$post_id = (int) $post->ID;

	$terms = get_object_term_cache( $post_id, $taxonomy );
	if ( empty( $terms ) )
		 $terms = wp_get_object_terms( $post_id, $taxonomy );
	if ( empty( $terms ) ) return false;

	if ( empty( $tag ) ) return ( !empty( $terms ) );

	$tag = (array) $tag;

	foreach ( $terms as $term ) {
		if ( in_array( $term->term_id, $tag ) ) return true;
		if ( in_array( $term->name, $tag ) ) return true;
		if ( in_array( $term->slug, $tag ) ) return true;
	}

	return false;
}

?>