Merge upstream branch
diff --git a/system/database/drivers/sqlite/sqlite_driver.php b/system/database/drivers/sqlite/sqlite_driver.php
index bb86c22..ffc57e7 100644
--- a/system/database/drivers/sqlite/sqlite_driver.php
+++ b/system/database/drivers/sqlite/sqlite_driver.php
@@ -43,7 +43,7 @@
 	public $dbdriver = 'sqlite';
 
 	// The character used to escape with - not needed for SQLite
-	protected $_escape_char = '';
+	protected $_escape_char = '"';
 
 	// clause and character used for LIKE escape sequences
 	protected $_like_escape_str = " ESCAPE '%s' ";
@@ -115,7 +115,7 @@
 	 */
 	public function reconnect()
 	{
-		// not implemented in SQLite
+		// Not supported in SQLite
 	}
 
 	// --------------------------------------------------------------------
@@ -123,10 +123,11 @@
 	/**
 	 * Select the database
 	 *
-	 * @return	resource
+	 * @return	bool
 	 */
 	public function db_select()
 	{
+		// Not needed, in SQLite every pseudo-connection is a database
 		return TRUE;
 	}
 
@@ -154,7 +155,9 @@
 	 */
 	protected function _execute($sql)
 	{
-		return @sqlite_query($this->conn_id, $sql);
+		return $this->is_write_type($sql)
+			? @sqlite_exec($this->conn_id, $sql)
+			: @sqlite_query($this->conn_id, $sql);
 	}
 
 	// --------------------------------------------------------------------
@@ -166,13 +169,8 @@
 	 */
 	public function trans_begin($test_mode = FALSE)
 	{
-		if ( ! $this->trans_enabled)
-		{
-			return TRUE;
-		}
-
 		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ($this->_trans_depth > 0)
+		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
 		{
 			return TRUE;
 		}
@@ -180,7 +178,7 @@
 		// Reset the transaction failure flag.
 		// If the $test_mode flag is set to TRUE transactions will be rolled back
 		// even if the queries produce a successful result.
-		$this->_trans_failure = ($test_mode === TRUE) ? TRUE : FALSE;
+		$this->_trans_failure = ($test_mode === TRUE);
 
 		$this->simple_query('BEGIN TRANSACTION');
 		return TRUE;
@@ -195,13 +193,8 @@
 	 */
 	public function trans_commit()
 	{
-		if ( ! $this->trans_enabled)
-		{
-			return TRUE;
-		}
-
 		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ($this->_trans_depth > 0)
+		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
 		{
 			return TRUE;
 		}
@@ -219,13 +212,8 @@
 	 */
 	public function trans_rollback()
 	{
-		if ( ! $this->trans_enabled)
-		{
-			return TRUE;
-		}
-
 		// When transactions are nested we only begin/commit/rollback the outermost ones
-		if ($this->_trans_depth > 0)
+		if ( ! $this->trans_enabled OR $this->_trans_depth > 0)
 		{
 			return TRUE;
 		}
@@ -260,9 +248,9 @@
 		// escape LIKE condition wildcards
 		if ($like === TRUE)
 		{
-			$str = str_replace(	array('%', '_', $this->_like_escape_chr),
-								array($this->_like_escape_chr.'%', $this->_like_escape_chr.'_', $this->_like_escape_chr.$this->_like_escape_chr),
-								$str);
+			return str_replace(array('%', '_', $this->_like_escape_chr),
+						array($this->_like_escape_chr.'%', $this->_like_escape_chr.'_', $this->_like_escape_chr.$this->_like_escape_chr),
+						$str);
 		}
 
 		return $str;
@@ -301,7 +289,7 @@
 	 * the specified database
 	 *
 	 * @param	string
-	 * @return	string
+	 * @return	int
 	 */
 	public function count_all($table = '')
 	{
@@ -316,9 +304,9 @@
 			return 0;
 		}
 
-		$row = $query->row();
-		$this->_reset_select();
-		return (int) $row->numrows;
+		$query = $query->row();
+		$this->_data_seek(0);
+		return (int) $query->numrows;
 	}
 
 	// --------------------------------------------------------------------
@@ -333,12 +321,13 @@
 	 */
 	protected function _list_tables($prefix_limit = FALSE)
 	{
-		$sql = "SELECT name from sqlite_master WHERE type='table'";
+		$sql = "SELECT name FROM sqlite_master WHERE type='table'";
 
-		if ($prefix_limit !== FALSE AND $this->dbprefix != '')
+		if ($prefix_limit !== FALSE && $this->dbprefix != '')
 		{
-			$sql .= " AND 'name' LIKE '".$this->escape_like_str($this->dbprefix)."%' ".sprintf($this->_like_escape_str, $this->_like_escape_chr);
+			return $sql." AND 'name' LIKE '".$this->escape_like_str($this->dbprefix)."%' ".sprintf($this->_like_escape_str, $this->_like_escape_chr);
 		}
+
 		return $sql;
 	}
 
@@ -370,7 +359,7 @@
 	 */
 	protected function _field_data($table)
 	{
-		return "SELECT * FROM ".$table." LIMIT 1";
+		return 'SELECT * FROM '.$table.' LIMIT 1';
 	}
 
 	// --------------------------------------------------------------------
@@ -411,24 +400,20 @@
 		{
 			if (strpos($item, '.'.$id) !== FALSE)
 			{
-				$str = $this->_escape_char. str_replace('.', $this->_escape_char.'.', $item);
+				$item = str_replace('.', $this->_escape_char.'.', $item);
 
 				// remove duplicates if the user already included the escape
-				return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $str);
+				return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $this->_escape_char.$item);
 			}
 		}
 
 		if (strpos($item, '.') !== FALSE)
 		{
-			$str = $this->_escape_char.str_replace('.', $this->_escape_char.'.'.$this->_escape_char, $item).$this->_escape_char;
-		}
-		else
-		{
-			$str = $this->_escape_char.$item.$this->_escape_char;
+			$item = str_replace('.', $this->_escape_char.'.'.$this->_escape_char, $item);
 		}
 
 		// remove duplicates if the user already included the escape
-		return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $str);
+		return preg_replace('/['.$this->_escape_char.']+/', $this->_escape_char, $this->_escape_char.$item.$this->_escape_char);
 	}
 
 	// --------------------------------------------------------------------
@@ -466,7 +451,7 @@
 	 */
 	protected function _insert($table, $keys, $values)
 	{
-		return "INSERT INTO ".$table." (".implode(', ', $keys).") VALUES (".implode(', ', $values).")";
+		return 'INSERT INTO '.$table.' ('.implode(', ', $keys).') VALUES ('.implode(', ', $values).')';
 	}
 
 	// --------------------------------------------------------------------
@@ -487,20 +472,13 @@
 	{
 		foreach ($values as $key => $val)
 		{
-			$valstr[] = $key." = ".$val;
+			$valstr[] = $key.' = '.$val;
 		}
 
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		$orderby = (count($orderby) >= 1)?' ORDER BY '.implode(", ", $orderby):'';
-
-		$sql = "UPDATE ".$table." SET ".implode(', ', $valstr);
-
-		$sql .= ($where != '' AND count($where) >=1) ? " WHERE ".implode(" ", $where) : '';
-
-		$sql .= $orderby.$limit;
-
-		return $sql;
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
+			.(($where != '' && count($where) > 0) ? ' WHERE '.implode(' ', $where) : '')
+			.(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '')
+			.( ! $limit ? '' : ' LIMIT '.$limit);
 	}
 
 
@@ -539,19 +517,16 @@
 
 		if (count($where) > 0 OR count($like) > 0)
 		{
-			$conditions = "\nWHERE ";
-			$conditions .= implode("\n", $this->ar_where);
+			$conditions = "\nWHERE ".implode("\n", $this->ar_where);
 
 			if (count($where) > 0 && count($like) > 0)
 			{
-				$conditions .= " AND ";
+				$conditions .= ' AND ';
 			}
 			$conditions .= implode("\n", $like);
 		}
 
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		return "DELETE FROM ".$table.$conditions.$limit;
+		return 'DELETE FROM '.$table.$conditions.( ! $limit ? '' : ' LIMIT '.$limit);
 	}
 
 	// --------------------------------------------------------------------
@@ -568,16 +543,7 @@
 	 */
 	protected function _limit($sql, $limit, $offset)
 	{
-		if ($offset == 0)
-		{
-			$offset = '';
-		}
-		else
-		{
-			$offset .= ", ";
-		}
-
-		return $sql."LIMIT ".$offset.$limit;
+		return $sql.'LIMIT '.($offset == 0 ? '' : $offset.', ').$limit;
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/sqlite/sqlite_forge.php b/system/database/drivers/sqlite/sqlite_forge.php
index 068a556..4c91cc3 100644
--- a/system/database/drivers/sqlite/sqlite_forge.php
+++ b/system/database/drivers/sqlite/sqlite_forge.php
@@ -59,12 +59,9 @@
 	{
 		if ( ! @file_exists($this->db->database) OR ! @unlink($this->db->database))
 		{
-			if ($this->db->db_debug)
-			{
-				return $this->db->display_error('db_unable_to_drop');
-			}
-			return FALSE;
+			return ($this->db->db_debug) ? $this->db->display_error('db_unable_to_drop') : FALSE;
 		}
+
 		return TRUE;
 	}
 
@@ -90,54 +87,29 @@
 			$sql .= 'IF NOT EXISTS ';
 		}
 
-		$sql .= $this->db->_escape_identifiers($table)."(";
+		$sql .= $this->db->_escape_identifiers($table).'(';
 		$current_field_count = 0;
 
-		foreach ($fields as $field=>$attributes)
+		foreach ($fields as $field => $attributes)
 		{
 			// Numeric field names aren't allowed in databases, so if the key is
 			// numeric, we know it was assigned by PHP and the developer manually
 			// entered the field information, so we'll simply add it to the list
 			if (is_numeric($field))
 			{
-				$sql .= "\n\t$attributes";
+				$sql .= "\n\t".$attributes;
 			}
 			else
 			{
 				$attributes = array_change_key_case($attributes, CASE_UPPER);
 
-				$sql .= "\n\t".$this->db->protect_identifiers($field);
-
-				$sql .=  ' '.$attributes['TYPE'];
-
-				if (array_key_exists('CONSTRAINT', $attributes))
-				{
-					$sql .= '('.$attributes['CONSTRAINT'].')';
-				}
-
-				if (array_key_exists('UNSIGNED', $attributes) && $attributes['UNSIGNED'] === TRUE)
-				{
-					$sql .= ' UNSIGNED';
-				}
-
-				if (array_key_exists('DEFAULT', $attributes))
-				{
-					$sql .= ' DEFAULT \''.$attributes['DEFAULT'].'\'';
-				}
-
-				if (array_key_exists('NULL', $attributes) && $attributes['NULL'] === TRUE)
-				{
-					$sql .= ' NULL';
-				}
-				else
-				{
-					$sql .= ' NOT NULL';
-				}
-
-				if (array_key_exists('AUTO_INCREMENT', $attributes) && $attributes['AUTO_INCREMENT'] === TRUE)
-				{
-					$sql .= ' AUTO_INCREMENT';
-				}
+				$sql .= "\n\t".$this->db->protect_identifiers($field)
+					.' '.$attributes['TYPE']
+					.( ! empty($attributes['CONSTRAINT']) ? '('.$attributes['CONSTRAINT'].')' : '')
+					.(( ! empty($attributes['UNSIGNED']) && $attributes['UNSIGNED'] === TRUE) ? ' UNSIGNED' : '')
+					.(isset($attributes['DEFAULT']) ? ' DEFAULT \''.$attributes['DEFAULT'].'\'' : '')
+					.(( ! empty($attributes['NULL']) && $attributes['NULL'] === TRUE) ? ' NULL' : ' NOT NULL')
+					.(( ! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === TRUE) ? ' AUTO_INCREMENT' : '');
 			}
 
 			// don't add a comma on the end of the last field
@@ -149,8 +121,7 @@
 
 		if (count($primary_keys) > 0)
 		{
-			$primary_keys = $this->db->protect_identifiers($primary_keys);
-			$sql .= ",\n\tPRIMARY KEY (" . implode(', ', $primary_keys) . ")";
+			$sql .= ",\n\tPRIMARY KEY (".implode(', ', $this->db->protect_identifiers($primary_keys)).')';
 		}
 
 		if (is_array($keys) && count($keys) > 0)
@@ -166,13 +137,11 @@
 					$key = array($this->db->protect_identifiers($key));
 				}
 
-				$sql .= ",\n\tUNIQUE (" . implode(', ', $key) . ")";
+				$sql .= ",\n\tUNIQUE (".implode(', ', $key).')';
 			}
 		}
 
-		$sql .= "\n)";
-
-		return $sql;
+		return $sql."\n)";
 	}
 
 	// --------------------------------------------------------------------
@@ -180,15 +149,11 @@
 	/**
 	 * Drop Table
 	 *
-	 * @return	bool
+	 * @return	string
 	 */
 	public function _drop_table($table)
 	{
-		if ($this->db->db_debug)
-		{
-			return $this->db->display_error('db_unsuported_feature');
-		}
-		return array();
+		return 'DROP TABLE '.$table.' IF EXISTS';
 	}
 
 	// --------------------------------------------------------------------
@@ -210,40 +175,21 @@
 	 */
 	public function _alter_table($alter_type, $table, $column_name, $column_definition = '', $default_value = '', $null = '', $after_field = '')
 	{
-		$sql = 'ALTER TABLE '.$this->db->protect_identifiers($table).' '.$alter_type.' '.$this->db->protect_identifiers($column_name);
-
-		// DROP has everything it needs now.
-		if ($alter_type == 'DROP')
+		/* SQLite only supports adding new columns and it does
+		 * NOT support the AFTER statement. Each new column will
+		 * be added as the last one in the table.
+		 */
+		if ($alter_type !== 'ADD COLUMN')
 		{
-			// SQLite does not support dropping columns
-			// http://www.sqlite.org/omitted.html
-			// http://www.sqlite.org/faq.html#q11
+			// Not supported
 			return FALSE;
 		}
 
-		$sql .= " $column_definition";
-
-		if ($default_value != '')
-		{
-			$sql .= " DEFAULT \"$default_value\"";
-		}
-
-		if ($null === NULL)
-		{
-			$sql .= ' NULL';
-		}
-		else
-		{
-			$sql .= ' NOT NULL';
-		}
-
-		if ($after_field != '')
-		{
-			return $sql.' AFTER '.$this->db->protect_identifiers($after_field);
-		}
-
-		return $sql;
-
+		return 'ALTER TABLE '.$this->db->protect_identifiers($table).' '.$alter_type.' '.$this->db->protect_identifiers($column_name)
+			.' '.$column_definition
+			.($default_value != '' ? ' DEFAULT "'.$default_value.'"' : '')
+			// If NOT NULL is specified, the field must have a DEFAULT value other than NULL
+			.(($null !== NULL && $default_value !== 'NULL') ? ' NOT NULL' : ' NULL');
 	}
 
 	// --------------------------------------------------------------------
diff --git a/system/database/drivers/sqlite/sqlite_result.php b/system/database/drivers/sqlite/sqlite_result.php
index b002aef..ebc8ce9 100644
--- a/system/database/drivers/sqlite/sqlite_result.php
+++ b/system/database/drivers/sqlite/sqlite_result.php
@@ -70,7 +70,7 @@
 	public function list_fields()
 	{
 		$field_names = array();
-		for ($i = 0; $i < $this->num_fields(); $i++)
+		for ($i = 0, $c = $this->num_fields(); $i < $c; $i++)
 		{
 			$field_names[] = sqlite_field_name($this->result_id, $i);
 		}
@@ -90,16 +90,14 @@
 	public function field_data()
 	{
 		$retval = array();
-		for ($i = 0; $i < $this->num_fields(); $i++)
+		for ($i = 0, $c = $this->num_fields(); $i < $c; $i++)
 		{
-			$F				= new stdClass();
-			$F->name		= sqlite_field_name($this->result_id, $i);
-			$F->type		= 'varchar';
-			$F->max_length	= 0;
-			$F->primary_key = 0;
-			$F->default		= '';
-
-			$retval[] = $F;
+			$retval[$i]			= new stdClass();
+			$retval[$i]->name		= sqlite_field_name($this->result_id, $i);
+			$retval[$i]->type		= 'varchar';
+			$retval[$i]->max_length		= 0;
+			$retval[$i]->primary_key	= 0;
+			$retval[$i]->default		= '';
 		}
 
 		return $retval;
@@ -114,7 +112,7 @@
 	 */
 	public function free_result()
 	{
-		// Not implemented in SQLite
+		// Not supported in SQLite
 	}
 
 	// --------------------------------------------------------------------
@@ -162,17 +160,9 @@
 		{
 			return sqlite_fetch_object($this->result_id);
 		}
-		else
-		{
-			$arr = sqlite_fetch_array($this->result_id, SQLITE_ASSOC);
-			if (is_array($arr))
-			{
-				$obj = (object) $arr;
-				return $obj;
-			} else {
-				return NULL;
-			}
-		}
+
+		$arr = sqlite_fetch_array($this->result_id, SQLITE_ASSOC);
+		return is_array($arr) ? (object) $arr : FALSE;
 	}
 
 }