root/trunk/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', 'number' => 0,
        '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;

    // SQL cannot save you; this is a second (potentially different) sort on a subset of data.
    if ( 'name' == $orderby )
        uasort( $tags, create_function('$a, $b', 'return strnatcasecmp($a->name, $b->name);') );
    else
        uasort( $tags, create_function('$a, $b', 'return ($a->count < $b->count);') );

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

    if ( $number > 0 )
        $tags = array_slice($tags, 0, $number);

    $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;

    $a = array();

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

    foreach ( $tags as $key => $tag ) {
        $count = $counts[ $key ];
        $tag_link = clean_url( $tag->link );
        $tag_id = isset($tags[ $key ]->id) ? $tags[ $key ]->id : $key;
        $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 =&