root/tags/2.0.9/wp-includes/template-functions-category.php

<?php

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

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

    if ( !isset($category_cache[$id]) )
        update_post_category_cache($id);

    $categories = $category_cache[$id];

    if ( !empty($categories) )
        sort($categories);
    else
        $categories = array();

    return $categories;
}

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

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

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

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

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

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

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

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

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

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

    if ( $parent->category_parent )
        $chain .= get_category_parents($parent->category_parent, $link, $separator, $nicename);

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

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

    $cat_ids = get_all_category_ids();
    foreach ( $cat_ids as $cat_id ) {
        if ( $cat_id == $id)
            continue;

        $category = get_category($cat_id);
        if ( $category->category_parent == $id ) {
            $chain .= $before.$category->cat_ID.$after;
            $chain .= get_category_children($category->cat_ID, $before, $after);
        }
    }
    return $chain;
}

// Deprecated.
function the_category_ID($echo = true) {
    // Grab the first cat in the list.
    $categories = get_the_category();
    $cat = $categories[0]->cat_ID;

    if ( $echo )
        echo $cat;

    return $cat;
}

// Deprecated.
function the_category_head($before='', $after='') {
    global $currentcat, $previouscat;
    // Grab the first cat in the list.
    $categories = get_the_category();
    $currentcat = $categories[0]->category_id;
    if ( $currentcat != $previouscat ) {
        echo $before;
        echo get_the_category_by_ID($currentcat);
        echo $after;
        $previouscat = $currentcat;
    }
}

function category_description($category = 0) {
    global $cat;
    if ( !$category )
        $category = $cat;
    $category = & get_category($category);
    return apply_filters('category_description', $category->category_description, $category->cat_ID);
}

// out of the WordPress loop
function dropdown_cats($optionall = 1, $all = 'All', $sort_column = 'ID', $sort_order = 'asc',
        $optiondates = 0, $optioncount = 0, $hide_empty = 1, $optionnone=FALSE,
        $selected=0, $hide=0) {
    global $wpdb;
    if ( ($file == 'blah') || ($file == '') )
        $file = get_settings('home') . '/';
    if ( !$selected )
        $selected=$cat;
    $sort_column = 'cat_'.$sort_column;

    $query = "
        SELECT cat_ID, cat_name, category_nicename,category_parent,
        COUNT($wpdb->post2cat.post_id) AS cat_count,
        DAYOFMONTH(MAX(post_date)) AS lastday, MONTH(MAX(post_date)) AS lastmonth
        FROM $wpdb->categories LEFT JOIN $wpdb->post2cat ON (cat_ID = category_id)
        LEFT JOIN $wpdb->posts ON (ID = post_id)
        WHERE cat_ID > 0
        ";
    if ( $hide ) {
        $query .= " AND cat_ID != $hide";
        $query .= get_category_children($hide, " AND cat_ID != ");
    }
    $query .=" GROUP BY cat_ID";
    if ( intval($hide_empty) == 1 )
        $query .= " HAVING cat_count > 0";
    $query .= " ORDER BY $sort_column $sort_order, post_date DESC";

    $categories = $wpdb->get_results($query);
    echo "<select name='cat' class='postform'>\n";
    if ( intval($optionall) == 1 ) {
        $all = apply_filters('list_cats', $all);
        echo "\t<option value='0'>$all</option>\n";
    }
    if ( intval($optionnone) == 1 )
        echo "\t<option value='-1'>".__('None')."</option>\n";
    if ( $categories ) {
        foreach ( $categories as $category ) {
            $cat_name = apply_filters('list_cats', $category->cat_name, $category);
            echo "\t<option value=\"".$category->cat_ID."\"";
            if ( $category->cat_ID == $selected )
                echo ' selected="selected"';
            echo '>';
            echo $cat_name;
            if ( intval($optioncount) == 1 )
                echo '&nbsp;&nbsp;('.$category->cat_count.')';
            if ( intval($optiondates) == 1 )
                echo '&nbsp;&nbsp;'.$category->lastday.'/'.$category->lastmonth;
            echo "</option>\n";
        }
    }
    echo "</select>\n";
}

// out of the WordPress loop
function wp_list_cats($args = '') {
    parse_str($args, $r);
    if ( !isset($r['optionall']))
        $r['optionall'] = 0;
    if ( !isset($r['all']))
        $r['all'] = 'All';
    if ( !isset($r['sort_column']) )
        $r['sort_column'] = 'ID';
    if ( !isset($r['sort_order']) )
        $r['sort_order'] = 'asc';
    if ( !isset($r['file']) )
        $r['file'] = '';
    if ( !isset($r['list']) )
        $r['list'] = true;
    if ( !isset($r['optiondates']) )
        $r['optiondates'] = 0;
    if ( !isset($r['optioncount']) )
        $r['optioncount'] = 0;
    if ( !isset($r['hide_empty']) )
        $r['hide_empty'] = 1;
    if ( !isset($r['use_desc_for_title']) )
        $r['use_desc_for_title'] = 1;
    if ( !isset($r['children']) )
        $r['children'] = true;
    if ( !isset($r['child_of']) )
        $r['child_of'] = 0;
    if ( !isset($r['categories']) )
        $r['categories'] = 0;
    if ( !isset($r['recurse']) )
        $r['recurse'] = 0;
    if ( !isset($r['feed']) )
        $r['feed'] = '';
    if ( !isset($r['feed_image']) )
        $r['feed_image'] = '';
    if ( !isset($r['exclude']) )
        $r['exclude'] = '';
    if ( !isset($r['hierarchical']) )
        $r['hierarchical'] = true;

    return list_cats($r['optionall'], $r['all'], $r['sort_column'], $r['sort_order'], $r['file'],    $r['list'], $r['optiondates'], $r['optioncount'], $r['hide_empty'], $r['use_desc_for_title'], $r['children'], $r['child_of'], $r['categories'], $r['recurse'], $r['feed'], $r['feed_image'], $r['exclude'], $r['hierarchical']);
}

function list_cats($optionall = 1, $all = 'All', $sort_column = 'ID', $sort_order = 'asc', $file = '', $list = true, $optiondates = 0, $optioncount = 0, $hide_empty = 1, $use_desc_for_title = 1, $children=FALSE, $child_of=0, $categories=0, $recurse=0, $feed = '', $feed_image = '', $exclude = '', $hierarchical=FALSE) {
    global $wpdb, $wp_query;
    // Optiondates now works
    if ( '' == $file )
        $file = get_settings('home') . '/';

    $exclusions = '';
    if ( !empty($exclude) ) {
        $excats = preg_split('/[\s,]+/',$exclude);
        if ( count($excats) ) {
            foreach ( $excats as $excat ) {
                $exclusions .= ' AND cat_ID <> ' . intval($excat) . ' ';
            }
        }
    }

    $exclusions = apply_filters('list_cats_exclusions', $exclusions );

    if ( intval($categories) == 0 ) {
        $sort_column = 'cat_'.$sort_column;

        $query = "
            SELECT cat_ID, cat_name, category_nicename, category_description, category_parent, category_count
            FROM $wpdb->categories
            WHERE cat_ID > 0 $exclusions
            ORDER BY $sort_column $sort_order";

        $categories = $wpdb->get_results($query);
    }

    if ( $optiondates ) {
        $cat_dates = $wpdb->get_results("    SELECT category_id,
        UNIX_TIMESTAMP( MAX(post_date) ) AS ts
        FROM $wpdb->posts, $wpdb->post2cat, $wpdb->categories
        WHERE post_status = 'publish' AND post_id = ID $exclusions
        GROUP BY category_id");
        foreach ( $cat_dates as $cat_date ) {
            $category_timestamp["$cat_date->category_id"] = $cat_date->ts;
        }
    }

    $num_found=0;
    $thelist = "";

    foreach ( (array) $categories as $category ) {
        if ( ( intval($hide_empty) == 0 || $category->category_count) && (!$hierarchical || $category->category_parent == $child_of) ) {
            $num_found++;
            $link = '<a href="'.get_category_link($category->cat_ID).'" ';
            if ( $use_desc_for_title == 0 || empty($category->category_description) )
                $link .= 'title="'. sprintf(__("View all posts filed under %s"), attribute_escape($category->cat_name)) . '"';
            else
                $link .= 'title="' . attribute_escape(apply_filters('category_description',$category->category_description,$category)) . '"';
            $link .= '>';
            $link .= apply_filters('list_cats', $category->cat_name, $category).'</a>';

            if ( (! empty($feed_image)) || (! empty($feed)) ) {

                $link .= ' ';

                if ( empty($feed_image) )
                    $link .= '(';

                $link .= '<a href="' . get_category_rss_link(0, $category->cat_ID, $category->category_nicename) . '"';

                if ( !empty($feed) ) {
                    $title = ' title="' . $feed . '"';
                    $alt = ' alt="' . $feed . '"';
                    $name = $feed;
                    $link .= $title;
                }

                $link .= '>';

                if ( !empty($feed_image) )
                    $link .= "<img src='$feed_image' $alt$title" . ' />';
                else
                    $link .= $name;

                $link .= '</a>';

                if (empty($feed_image))
                    $link .= ')';
            }

            if ( intval($optioncount) == 1 )
                $link .= ' ('.intval($category->category_count).')';

            if ( $optiondates ) {
                if ( $optiondates == 1 )
                    $optiondates = 'Y-m-d';
                $link .= ' ' . gmdate($optiondates, $category_timestamp["$category->cat_ID"]);
            }

            if ( $list ) {
                $thelist .= "\t<li";
                if (($category->cat_ID == $wp_query->get_queried_object_id()) && is_category()) {
                    $thelist .=  ' class="current-cat"';
                }
                $thelist .= ">$link\n";
            } else {
                $thelist .= "\t$link<br />\n";
            }

            if ($hierarchical && $children)
                $thelist .= list_cats($optionall, $all, $sort_column, $sort_order, $file, $list, $optiondates, $optioncount, $hide_empty, $use_desc_for_title, $hierarchical, $category->cat_ID, $categories, 1, $feed, $feed_image, $exclude, $hierarchical);
            if ($list)
                $thelist .= "</li>\n";
        }
    }
    if ( !$num_found && !$child_of ) {
        if ( $list ) {
            $before = '<li>';
            $after = '</li>';
        }
        echo $before . __("No categories") . $after . "\n";
        return;
    }
    if ( $list && $child_of && $num_found && $recurse ) {
        $pre = "\t\t<ul class='children'>";
        $post = "\t\t</ul>\n";
    } else {
        $pre = $post = '';
    }
    $thelist = $pre . $thelist . $post;
    if ( $recurse )
        return $thelist;
    echo apply_filters('list_cats', $thelist);
}

function in_category($category) { // Check if the current post is in the given category
    global $category_cache, $post;

    if ( isset( $category_cache[$post->ID][$category] ) )
        return true;
    else
        return false;
}

?>