root/tags/2.3.1/wp-includes/category-template.php

<?php

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

    $chain = '';
    // TODO: consult hierarchy
    $cat_ids = get_all_category_ids();
    foreach ( $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 ) {
            $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){
    $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) )
        $chain .= get_category_parents($parent->parent, $link, $separator, $nicename);

    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, $term_cache, $blog_id;

    $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_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='') {
    global $wp_rewrite;
    $categories = get_the_category();
    if (empty($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);
}

function in_category( $category ) { // Check if the current post is in the given category
    global $post, $blog_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 = '', $parents='') {
    echo get_the_category_list($separator, $parents);
}

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'
    );

    $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 );

    $categories = get_categories($r);

    $output = '';
    if ( ! empty($categories) ) {
        $output = "<select name='$name' id='$name' class='$class'>\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 = 0;  // 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_image' => '', 'exclude' => '',
        'hierarchical' => true, 'title_li' => __('Categories'),
        'echo' => 1
    );

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

        if ( $hierarchical )
            $depth = 0;  // Walk the full 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;

    $return = wp_generate_tag_cloud( $tags, $args ); // Here's where those top tags get sorted according to $args
    if ( is_wp_error( $return ) )
        return false;
    else 
        echo apply_filters( 'wp_tag_cloud', $return, $args );
}

// $tags = prefetched tag array ( get_tags() )
// $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', 'number' => 45,
        'format' => 'flat', 'orderby' => 'name', 'order' => 'ASC'
    );
    $args = wp_parse_args( $args, $defaults );
    extract($args);

    if ( !$tags )
        return;
    $counts = $tag_links = array();
    foreach ( (array) $tags as $tag ) {
        $counts[$tag->name] = $tag->count;
        $tag_links[$tag->name] = get_tag_link( $tag->term_id );
        if ( is_wp_error( $tag_links[$tag->name] ) )
            return $tag_links[$tag->name];
        $tag_ids[$tag->name] = $tag->term_id;
    }

    $min_count = min($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 );

    $a = array();

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

    foreach ( $counts as $tag => $count ) {
        $tag_id = $tag_ids[$tag];
        $tag_link = clean_url($tag_links[$tag]);
        $tag = str_replace(' ', '&nbsp;', wp_specialchars( $tag ));
        $a[] = "<a href='$tag_link' class='tag-link-$tag_id' title='" . attribute_escape( sprintf( __('%d topics'), $count ) ) . "'$rel style='font-size: " .
            ( $smallest + ( ( $count - $min_count ) * $font_step ) )
            . "$unit;'>$tag</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 ) {
    global $post;

     $id = (int) $id;

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

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

    $tags = get_object_term_cache