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+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * Database schema utilities
+ *
+ * PHP version 5
+ *
+ * LICENCE: This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * @category Database
+ * @package StatusNet
+ * @author Evan Prodromou <evan@status.net>
+ * @copyright 2009 StatusNet, Inc.
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link http://status.net/
+ */
+
+if (!defined('STATUSNET')) {
+ exit(1);
+}
+
+/**
+ * Class representing the database schema
+ *
+ * A class representing the database schema. Can be used to
+ * manipulate the schema -- especially for plugins and upgrade
+ * utilities.
+ *
+ * @category Database
+ * @package StatusNet
+ * @author Evan Prodromou <evan@status.net>
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link http://status.net/
+ */
+
+class Schema
+{
+ static $_single = null;
+ protected $conn = null;
+
+ /**
+ * Constructor. Only run once for singleton object.
+ */
+
+ protected function __construct()
+ {
+ // XXX: there should be an easier way to do this.
+ $user = new User();
+
+ $this->conn = $user->getDatabaseConnection();
+
+ $user->free();
+
+ unset($user);
+ }
+
+ /**
+ * Main public entry point. Use this to get
+ * the singleton object.
+ *
+ * @return Schema the (single) Schema object
+ */
+
+ static function get()
+ {
+ if (empty(self::$_single)) {
+ self::$_single = new Schema();
+ }
+ return self::$_single;
+ }
+
+ /**
+ * Returns a TableDef object for the table
+ * in the schema with the given name.
+ *
+ * Throws an exception if the table is not found.
+ *
+ * @param string $name Name of the table to get
+ *
+ * @return TableDef tabledef for that table.
+ */
+
+ public function getTableDef($name)
+ {
+ $res =& $this->conn->query('DESCRIBE ' . $name);
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ $td = new TableDef();
+
+ $td->name = $name;
+ $td->columns = array();
+
+ $row = array();
+
+ while ($res->fetchInto($row, DB_FETCHMODE_ASSOC)) {
+
+ $cd = new ColumnDef();
+
+ $cd->name = $row['Field'];
+
+ $packed = $row['Type'];
+
+ if (preg_match('/^(\w+)\((\d+)\)$/', $packed, $match)) {
+ $cd->type = $match[1];
+ $cd->size = $match[2];
+ } else {
+ $cd->type = $packed;
+ }
+
+ $cd->nullable = ($row['Null'] == 'YES') ? true : false;
+ $cd->key = $row['Key'];
+ $cd->default = $row['Default'];
+ $cd->extra = $row['Extra'];
+
+ $td->columns[] = $cd;
+ }
+
+ return $td;
+ }
+
+ /**
+ * Gets a ColumnDef object for a single column.
+ *
+ * Throws an exception if the table is not found.
+ *
+ * @param string $table name of the table
+ * @param string $column name of the column
+ *
+ * @return ColumnDef definition of the column or null
+ * if not found.
+ */
+
+ public function getColumnDef($table, $column)
+ {
+ $td = $this->getTableDef($table);
+
+ foreach ($td->columns as $cd) {
+ if ($cd->name == $column) {
+ return $cd;
+ }
+ }
+
+ return null;
+ }
+
+ /**
+ * Creates a table with the given names and columns.
+ *
+ * @param string $name Name of the table
+ * @param array $columns Array of ColumnDef objects
+ * for new table.
+ *
+ * @return boolean success flag
+ */
+
+ public function createTable($name, $columns)
+ {
+ $uniques = array();
+ $primary = array();
+ $indices = array();
+
+ $sql = "CREATE TABLE $name (\n";
+
+ for ($i = 0; $i < count($columns); $i++) {
+
+ $cd =& $columns[$i];
+
+ if ($i > 0) {
+ $sql .= ",\n";
+ }
+
+ $sql .= $this->_columnSql($cd);
+
+ switch ($cd->key) {
+ case 'UNI':
+ $uniques[] = $cd->name;
+ break;
+ case 'PRI':
+ $primary[] = $cd->name;
+ break;
+ case 'MUL':
+ $indices[] = $cd->name;
+ break;
+ }
+ }
+
+ if (count($primary) > 0) { // it really should be...
+ $sql .= ",\nconstraint primary key (" . implode(',', $primary) . ")";
+ }
+
+ foreach ($uniques as $u) {
+ $sql .= ",\nunique index {$name}_{$u}_idx ($u)";
+ }
+
+ foreach ($indices as $i) {
+ $sql .= ",\nindex {$name}_{$i}_idx ($i)";
+ }
+
+ $sql .= "); ";
+
+ $res =& $this->conn->query($sql);
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Drops a table from the schema
+ *
+ * Throws an exception if the table is not found.
+ *
+ * @param string $name Name of the table to drop
+ *
+ * @return boolean success flag
+ */
+
+ public function dropTable($name)
+ {
+ $res =& $this->conn->query("DROP TABLE $name");
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Adds an index to a table.
+ *
+ * If no name is provided, a name will be made up based
+ * on the table name and column names.
+ *
+ * Throws an exception on database error, esp. if the table
+ * does not exist.
+ *
+ * @param string $table Name of the table
+ * @param array $columnNames Name of columns to index
+ * @param string $name (Optional) name of the index
+ *
+ * @return boolean success flag
+ */
+
+ public function createIndex($table, $columnNames, $name=null)
+ {
+ if (!is_array($columnNames)) {
+ $columnNames = array($columnNames);
+ }
+
+ if (empty($name)) {
+ $name = "$table_".implode("_", $columnNames)."_idx";
+ }
+
+ $res =& $this->conn->query("ALTER TABLE $table ".
+ "ADD INDEX $name (".
+ implode(",", $columnNames).")");
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Drops a named index from a table.
+ *
+ * @param string $table name of the table the index is on.
+ * @param string $name name of the index
+ *
+ * @return boolean success flag
+ */
+
+ public function dropIndex($table, $name)
+ {
+ $res =& $this->conn->query("ALTER TABLE $table DROP INDEX $name");
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Adds a column to a table
+ *
+ * @param string $table name of the table
+ * @param ColumnDef $columndef Definition of the new
+ * column.
+ *
+ * @return boolean success flag
+ */
+
+ public function addColumn($table, $columndef)
+ {
+ $sql = "ALTER TABLE $table ADD COLUMN " . $this->_columnSql($columndef);
+
+ $res =& $this->conn->query($sql);
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Modifies a column in the schema.
+ *
+ * The name must match an existing column and table.
+ *
+ * @param string $table name of the table
+ * @param ColumnDef $columndef new definition of the column.
+ *
+ * @return boolean success flag
+ */
+
+ public function modifyColumn($table, $columndef)
+ {
+ $sql = "ALTER TABLE $table MODIFY COLUMN " .
+ $this->_columnSql($columndef);
+
+ $res =& $this->conn->query($sql);
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Drops a column from a table
+ *
+ * The name must match an existing column.
+ *
+ * @param string $table name of the table
+ * @param string $columnName name of the column to drop
+ *
+ * @return boolean success flag
+ */
+
+ public function dropColumn($table, $columnName)
+ {
+ $sql = "ALTER TABLE $table DROP COLUMN $columnName";
+
+ $res =& $this->conn->query($sql);
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Ensures that a table exists with the given
+ * name and the given column definitions.
+ *
+ * If the table does not yet exist, it will
+ * create the table. If it does exist, it will
+ * alter the table to match the column definitions.
+ *
+ * @param string $tableName name of the table
+ * @param array $columns array of ColumnDef
+ * objects for the table
+ *
+ * @return boolean success flag
+ */
+
+ public function ensureTable($tableName, $columns)
+ {
+ // XXX: DB engine portability -> toilet
+
+ try {
+ $td = $this->getTableDef($tableName);
+ } catch (Exception $e) {
+ if (preg_match('/no such table/', $e->getMessage())) {
+ return $this->createTable($tableName, $columns);
+ } else {
+ throw $e;
+ }
+ }
+
+ $cur = $this->_names($td->columns);
+ $new = $this->_names($columns);
+
+ $toadd = array_diff($new, $cur);
+ $todrop = array_diff($cur, $new);
+ $same = array_intersect($new, $cur);
+ $tomod = array();
+
+ foreach ($same as $m) {
+ $curCol = $this->_byName($td->columns, $m);
+ $newCol = $this->_byName($columns, $m);
+
+ if (!$newCol->equals($curCol)) {
+ $tomod[] = $newCol->name;
+ }
+ }
+
+ if (count($toadd) + count($todrop) + count($tomod) == 0) {
+ // nothing to do
+ return true;
+ }
+
+ // For efficiency, we want this all in one
+ // query, instead of using our methods.
+
+ $phrase = array();
+
+ foreach ($toadd as $columnName) {
+ $cd = $this->_byName($columns, $columnName);
+
+ $phrase[] = 'ADD COLUMN ' . $this->_columnSql($cd);
+ }
+
+ foreach ($todrop as $columnName) {
+ $phrase[] = 'DROP COLUMN ' . $columnName;
+ }
+
+ foreach ($tomod as $columnName) {
+ $cd = $this->_byName($columns, $columnName);
+
+ $phrase[] = 'MODIFY COLUMN ' . $this->_columnSql($cd);
+ }
+
+ $sql = 'ALTER TABLE ' . $tableName . ' ' . implode(', ', $phrase);
+
+ $res =& $this->conn->query($sql);
+
+ if (PEAR::isError($res)) {
+ throw new Exception($res->getMessage());
+ }
+
+ return true;
+ }
+
+ /**
+ * Returns the array of names from an array of
+ * ColumnDef objects.
+ *
+ * @param array $cds array of ColumnDef objects
+ *
+ * @return array strings for name values
+ */
+
+ private function _names($cds)
+ {
+ $names = array();
+
+ foreach ($cds as $cd) {
+ $names[] = $cd->name;
+ }
+
+ return $names;
+ }
+
+ /**
+ * Get a ColumnDef from an array matching
+ * name.
+ *
+ * @param array $cds Array of ColumnDef objects
+ * @param string $name Name of the column
+ *
+ * @return ColumnDef matching item or null if no match.
+ */
+
+ private function _byName($cds, $name)
+ {
+ foreach ($cds as $cd) {
+ if ($cd->name == $name) {
+ return $cd;
+ }
+ }
+
+ return null;
+ }
+
+ /**
+ * Return the proper SQL for creating or
+ * altering a column.
+ *
+ * Appropriate for use in CREATE TABLE or
+ * ALTER TABLE statements.
+ *
+ * @param ColumnDef $cd column to create
+ *
+ * @return string correct SQL for that column
+ */
+
+ private function _columnSql($cd)
+ {
+ $sql = "{$cd->name} ";
+
+ if (!empty($cd->size)) {
+ $sql .= "{$cd->type}({$cd->size}) ";
+ } else {
+ $sql .= "{$cd->type} ";
+ }
+
+ if (!empty($cd->default)) {
+ $sql .= "default {$cd->default} ";
+ } else {
+ $sql .= ($cd->nullable) ? "null " : "not null ";
+ }
+
+ return $sql;
+ }
+}
+
+/**
+ * A class encapsulating the structure of a table.
+ *
+ * @category Database
+ * @package StatusNet
+ * @author Evan Prodromou <evan@status.net>
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link http://status.net/
+ */
+
+class TableDef
+{
+ /** name of the table */
+ public $name;
+ /** array of ColumnDef objects for the columns. */
+ public $columns;
+}
+
+/**
+ * A class encapsulating the structure of a column in a table.
+ *
+ * @category Database
+ * @package StatusNet
+ * @author Evan Prodromou <evan@status.net>
+ * @license http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link http://status.net/
+ */
+
+class ColumnDef
+{
+ /** name of the column. */
+ public $name;
+ /** type of column, e.g. 'int', 'varchar' */
+ public $type;
+ /** size of the column. */
+ public $size;
+ /** boolean flag; can it be null? */
+ public $nullable;
+ /**
+ * type of key: null = no key; 'PRI' => primary;
+ * 'UNI' => unique key; 'MUL' => multiple values.
+ */
+ public $key;
+ /** default value if any. */
+ public $default;
+ /** 'extra' stuff. Returned by MySQL, largely
+ * unused. */
+ public $extra;
+
+ /**
+ * Constructor.
+ *
+ * @param string $name name of the column
+ * @param string $type type of the column
+ * @param int $size size of the column
+ * @param boolean $nullable can this be null?
+ * @param string $key type of key
+ * @param value $default default value
+ * @param value $extra unused
+ */
+
+ function __construct($name=null, $type=null, $size=null,
+ $nullable=true, $key=null, $default=null,
+ $extra=null)
+ {
+ $this->name = strtolower($name);
+ $this->type = strtolower($type);
+ $this->size = $size+0;
+ $this->nullable = $nullable;
+ $this->key = $key;
+ $this->default = $default;
+ $this->extra = $extra;
+ }
+
+ /**
+ * Compares this columndef with another to see
+ * if they're functionally equivalent.
+ *
+ * @param ColumnDef $other column to compare
+ *
+ * @return boolean true if equivalent, otherwise false.
+ */
+
+ function equals($other)
+ {
+ return ($this->name == $other->name &&
+ $this->_typeMatch($other) &&
+ $this->_defaultMatch($other) &&
+ $this->_nullMatch($other) &&
+ $this->key == $other->key);
+ }
+
+ /**
+ * Does the type of this column match the
+ * type of the other column?
+ *
+ * Checks the type and size of a column. Tries
+ * to ignore differences between synonymous
+ * data types, like 'integer' and 'int'.
+ *
+ * @param ColumnDef $other other column to check
+ *
+ * @return boolean true if they're about equivalent
+ */
+
+ private function _typeMatch($other)
+ {
+ switch ($this->type) {
+ case 'integer':
+ case 'int':
+ return ($other->type == 'integer' ||
+ $other->type == 'int');
+ break;
+ default:
+ return ($this->type == $other->type &&
+ $this->size == $other->size);
+ }
+ }
+
+ /**
+ * Does the default behaviour of this column match
+ * the other?
+ *
+ * @param ColumnDef $other other column to check
+ *
+ * @return boolean true if defaults are effectively the same.
+ */
+
+ private function _defaultMatch($other)
+ {
+ return ((is_null($this->default) && is_null($other->default)) ||
+ ($this->default == $other->default));
+ }
+
+ /**
+ * Does the null behaviour of this column match
+ * the other?
+ *
+ * @param ColumnDef $other other column to check
+ *
+ * @return boolean true if these columns 'null' the same.
+ */
+
+ private function _nullMatch($other)
+ {
+ return ((!is_null($this->default) && !is_null($other->default) &&
+ $this->default == $other->default) ||
+ ($this->nullable == $other->nullable));
+ }
+}
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