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<?php rcs_id('$Id: DbaListSet.php,v 1.3 2004/11/21 11:59:14 rurban Exp $');
class DbaListSet
{
function DbaListSet(&$dbh) {
$this->_dbh = &$dbh;
}
function create_sequence($seq) {
$dbh = &$this->_dbh;
if (!$dbh->exists('max_key')) {
// echo "initializing DbaListSet";
// FIXME: check to see if it's really empty?
$dbh->insert('max_key', 0);
}
$key = "s" . urlencode($seq);
assert(intval($key) == 0 && !strstr($key, ':'));
if (!$dbh->exists($key))
$dbh->insert($key, "$key:$key:");
}
function delete_sequence($seq) {
$key = "s" . urlencode($seq);
for ($i = $this->firstkey($seq); $i; $i = $next) {
$next = $this->next($i);
$this->delete($i);
}
$this->_dbh->delete($key);
}
function firstkey($seq) {
$key = "s" . urlencode($seq);
list(, $next) = explode(':', $this->_dbh->fetch($key), 3);
return intval($next);
}
function lastkey($seq) {
$key = "s" . urlencode($seq);
list($prev) = explode(':', $this->_dbh->fetch($key), 3);
return intval($prev);
}
function next($i) {
list( , $next, ) = explode(':', $this->_dbh->fetch(intval($i)), 3);
return intval($next);
}
function prev(&$i) {
list( $prev , , ) = explode(':', $this->_dbh->fetch(intval($i)), 3);
return intval($prev);
}
function exists($i) {
$i = intval($i);
return $i && $this->_dbh->exists($i);
}
function fetch($i) {
list(, , $data) = explode(':', $this->_dbh->fetch(intval($i)), 3);
return $data;
}
function replace($i, $data) {
$dbh = &$this->_dbh;
list($prev, $next,) = explode(':', $dbh->fetch(intval($i)), 3);
$dbh->replace($i, "$prev:$next:$data");
}
function insert_before($i, $data) {
assert(intval($i));
return $this->_insert_before_nc($i, $data);
}
function insert_after($i, $data) {
assert(intval($i));
return $this->_insert_after_nc($i, $data);
}
function append($seq, $data) {
$key = "s" . urlencode($seq);
$this->_insert_before_nc($key, $data);
}
function prepend($seq, $data) {
$key = "s" . urlencode($seq);
$this->_insert_after_nc($key, $data);
}
function _insert_before_nc($i, &$data) {
$newkey = $this->_new_key();
$old_prev = $this->_setprev($i, $newkey);
$this->_setnext($old_prev, $newkey);
$this->_dbh->insert($newkey, "$old_prev:$i:$data");
return $newkey;
}
function _insert_after_nc($i, &$data) {
$newkey = $this->_new_key();
$old_next = $this->_setnext($i, $newkey);
$this->_setprev($old_next, $newkey);
$this->_dbh->insert($newkey, "$i:$old_next:$data");
return $newkey;
}
function delete($i) {
$dbh = &$this->_dbh;
list($prev, $next) = explode(':', $dbh->fetch(intval($i)), 3);
$this->_setnext($prev, $next);
$this->_setprev($next, $prev);
$dbh->delete(intval($i));
}
function _new_key() {
$dbh = &$this->_dbh;
$new_key = $dbh->fetch('max_key') + 1;
$dbh->replace('max_key', $new_key);
return $new_key;
}
function _setprev($i, $new_prev) {
$dbh = &$this->_dbh;
list($old_prev, $next, $data) = explode(':', $dbh->fetch($i), 3);
$dbh->replace($i, "$new_prev:$next:$data");
return $old_prev;
}
function _setnext($i, $new_next) {
$dbh = &$this->_dbh;
list($prev, $old_next, $data) = explode(':', $dbh->fetch($i), 3);
$dbh->replace($i, "$prev:$new_next:$data");
return $old_next;
}
}
// For emacs users
// Local Variables:
// mode: php
// tab-width: 8
// c-basic-offset: 4
// c-hanging-comment-ender-p: nil
// indent-tabs-mode: nil
// End:
?>
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