sql = $sql;
		$this->variables = $variables;
	}
	public function append($querylet) {
		assert(!is_null($querylet));
		$this->sql .= $querylet->sql;
		$this->variables = array_merge($this->variables, $querylet->variables);
	}
	public function append_sql($sql) {
		$this->sql .= $sql;
	}
	public function add_variable($var) {
		$this->variables[] = $var;
	}
}
class TagQuerylet {
	var $tag;
	var $positive;
	public function TagQuerylet($tag, $positive) {
		$this->tag = $tag;
		$this->positive = $positive;
	}
}
class ImgQuerylet {
	var $qlet;
	var $positive;
	public function ImgQuerylet($qlet, $positive) {
		$this->qlet = $qlet;
		$this->positive = $positive;
	}
}
// }}}
// {{{ dbengines
class DBEngine {
	var $name = null;
	var $auto_increment = null;
	var $create_table_extras = "";
}
class MySQL extends DBEngine {
	var $name = "mysql";
	var $auto_increment = "INTEGER PRIMARY KEY auto_increment";
	var $create_table_extras = "TYPE=INNODB DEFAULT CHARSET='utf8'";
	function init($db) {
		$db->Execute("SET NAMES utf8;");
	}
}
class PostgreSQL extends DBEngine {
	var $name = "pgsql";
	var $auto_increment = "SERIAL PRIMARY KEY";
	function init($db) {
	}
}
//}}}
/*
 * A class for controlled database access
 */
class Database {
	var $db;
	var $extensions;
	var $cache_hits = 0, $cache_misses = 0;
	var $engine = null;
	/*
	 * Create a new database object using connection info
	 * stored in config.php in the root shimmie folder
	 */
	public function Database() {
		if(is_readable("config.php")) {
			require_once "config.php";
			$this->engine = new MySQL();
			$this->db = @NewADOConnection($database_dsn);
			$this->use_memcache = isset($memcache);
			if($this->db) {
				$this->db->SetFetchMode(ADODB_FETCH_ASSOC);
				$this->engine->init($this->db);
			}
			else {
				$version = VERSION;
				print "
				
					
						Internal error - Shimmie-$version
					
					
						Internal error: Could not connect to database
					
				
				";
				exit;
			}
			if($this->use_memcache) {
				$this->memcache = new Memcache;
				$this->memcache->pconnect('localhost', 11211) or ($this->use_memcache = false);
			}
		}
		else {
			header("Location: install.php");
			exit;
		}
	}
// memcache {{{
	public function cache_get($key) {
		assert(!is_null($key));
		if($this->use_memcache) {
			$val = $this->memcache->get($key);
			if($val) {
				$this->cache_hits++;
				return $val;
			}
			else {
				$this->cache_misses++;
			}
		}
		return false;
	}
	public function cache_set($key, $val, $time=0) {
		assert(!is_null($key));
		if($this->use_memcache) {
			$this->memcache->set($key, $val, false, $time);
		}
	}
	public function cache_delete($key) {
		assert(!is_null($key));
		if($this->use_memcache) {
			$this->memcache->delete($key);
		}
	}
// }}}
// safety wrapping {{{
	public function execute($query, $args=array()) {
		$result = $this->db->Execute($query, $args);
		if($result === False) {
			print "SQL Error: " . $this->db->ErrorMsg();
			print "
Query: $query";
			print "
Args: "; print_r($args);
			exit;
		}
		return $result;
	}
	public function get_all($query, $args=array()) {
		$result = $this->db->GetAll($query, $args);
		if($result === False) {
			print "SQL Error: " . $this->db->ErrorMsg();
			print "
Query: $query";
			print "
Args: "; print_r($args);
			exit;
		}
		return $result;
	}
	public function get_row($query, $args=array()) {
		$result = $this->db->GetRow($query, $args);
		if($result === False) {
			print "SQL Error: " . $this->db->ErrorMsg();
			print "
Query: $query";
			print "
Args: "; print_r($args);
			exit;
		}
		if(count($result) == 0) {
			return null;
		}
		else {
			return $result;
		}
	}
	public function upgrade_schema($filename) {
		$this->install_schema($filename);
	}
	public function install_schema($filename) {
		//print "
upgrading $filename";
		global $config;
		if($config->get_bool("in_upgrade")) return;
		$config->set_bool("in_upgrade", true);
		require_once "lib/adodb/adodb-xmlschema03.inc.php";
		$schema = new adoSchema($this->db);
		$sql = $schema->ParseSchema($filename);
		//echo ""; var_dump($sql); echo "
";
		$result = $schema->ExecuteSchema();
		if(!$result) {
			die("Error creating tables from XML schema ($filename)");
		}
		$config->set_bool("in_upgrade", false);
	}
// }}}
// tags {{{
// }}}
}
?>