php从数据库查询结果生成树形列表的方法

<?php
/* Here are the database definitions (for Solid) that i use in this code.
 * It should not be hard to adapt it to another database.
 */
/*
CREATE TABLE dirent_types (
 id INTEGER NOT NULL,
 icon VARCHAR(50),
 name VARCHAR(50),
 PRIMARY KEY(id)
);
INSERT INTO dirent_types VALUES(1, folderclosed, Directory);
INSERT INTO dirent_types VALUES(2, document, File);
CREATE TABLE directory (
 id INTEGER NOT NULL,
 parent INTEGER REFERENCES directory(id),
 name VARCHAR(200),
 icon VARCHAR(50),
 type INTEGER REFERENCES dirent_types(id),
 url VARCHAR(200),
 PRIMARY KEY(id)
);
DROP INDEX directory_idx;
CREATE UNIQUE INDEX directory_idx ON directory(parent, name);
CREATE SEQUENCE dirent_id;
"CREATE PROCEDURE insert_dir_entry
 (name VARCHAR, parent INTEGER, type INTEGER)
 RETURNS(id INTEGER)
BEGIN
 EXEC SQL WHENEVER SQLERROR ABORT;
 EXEC SEQUENCE dirent_id.NEXT INTO id;
 EXEC SQL PREPARE c_insert
 INSERT INTO directory
 (id, parent, type, name)
 VALUES(?, ?, ?, ?);
 EXEC SQL EXECUTE c_insert USING (id, parent, type, name);
 EXEC SQL DROP c_insert;
END";
CALL insert_dir_entry(My Computer, NULL, 1);
CALL insert_dir_entry(Network Neighbourhood, NULL, 1);
CALL insert_dir_entry(lucifer.guardian.no, 2, 1);
CALL insert_dir_entry(rafael.guardian.no, 2, 1);
CALL insert_dir_entry(uriel.guardian.no, 2, 1);
CALL insert_dir_entry(Control Panel, NULL, 1);
CALL insert_dir_entry(Services, 6, 1);
CALL insert_dir_entry(Apache, 7, 2);
CALL insert_dir_entry(Solid Server 2.2, 7, 2);
*/
function icon($icon, $name = , $width = 0, $height = 0) {
 global $DOCUMENT_ROOT;
 $icon_loc = /pics/menu;
 $file = "$DOCUMENT_ROOT$icon_loc/$icon.gif";
 if (!$width || !$height) {
 $iconinfo = getimagesize($file);
 if (!$width) {
 $width = $iconinfo[0];
 }
 if (!$height) {
 $height = $iconinfo[1];
 }
 }
 printf( <img%s border=0 align=top src="/pics/menu/%s.gif" .
 width="%d" height="%d">, $name ? " name=\"$name\"" : ,
 $icon, $width, $height);
}
function display_directory($parent,$showdepth=0,$ancestors=false){
 global $child_nodes, $node_data, $last_child;
 reset($child_nodes[$parent]);
 $size = sizeof($child_nodes[$parent]);
 $lastindex = $size - 1;
 if (!$ancestors) {
 $ancestors = array();
 }
 $depth = sizeof($ancestors);
 printf( <div id="node_%d" class="dirEntry" visibility="%s">,
 $parent, $showdepth > 0 ? show : hide);
 while (list($index, $node) = each($child_nodes[$parent])) {
 for ($i = 0; $i < $depth; $i++) {
 $up_parent = (int)$node_data[$ancestors[$i]][ parent];
 $last_node_on_generation = $last_child[$up_parent];
 $uptree_node_on_generation = $ancestors[$i];
 if ($last_node_on_generation == $uptree_node_on_generation) {
 icon( "blank");
 } else {
 icon( "line");
 }
 }
 if ($child_nodes[$node]) {
 // has children, i.e. it is a folder
 $conn_icon = "plus";
 $expand = true;
 } else {
 $conn_icon = "join";
 $expand = false;
 }
 if ($index == $lastindex) {
 $conn_icon .= "bottom";
 } elseif ($depth == 0 && $index == 0) {
 $conn_icon .= "top";
 }
 if ($expand) {
 printf( "<a href=\"javascript:document.layers[node_%d].visibility=show\">", $node);
 }
 icon($conn_icon, "connImg_$node");
 if ($expand) {
 print( "</a>");
 }
 $icon = $node_data[$node][ icon];
 if (!$icon) {
 $type = $node_data[$node][ type];
 $icon = $GLOBALS[ dirent_icons][$type];
 }
 icon($icon, "nodeImg_$node");
 $name = $node_data[$node][ name];
 printf( ?<font size="%d">%s</font><br%c>, -1, $name, 10);
 if ($child_nodes[$node]) {
 $newdepth = $showdepth;
 if ($newdepth > 0) {
 $newdepth--;
 }
 $new_ancestors = $ancestors;
 $new_ancestors[] = $node;
 display_directory($node, $newdepth, $new_ancestors);
 }
 }
 print( "</div\n>");
}
function setup_directory($parent, $maxdepth)
{
 global $dirent_icons, $child_nodes, $node_data, $last_child;
 $dirent_icons = sql_assoc(SELECT id,icon FROM dirent_types);
 $query = SELECT id,parent,type,icon,name .
 FROM directory .
 ORDER BY parent,name;
 $child_nodes = array();
 $node_data = array();
 $res = sql($query);
 while (list($id,$parent,$type,$icon,$name)=db_fetch_row($res)){
 $child_nodes[(int)$parent][] = $id;
 $node_data[$id] = array( id => $id,
 parent => $parent,
 type => $type,
 icon => $icon,
 name => $name);
 $last_child[(int)$parent] = $id;
 }
}
?>