<?php

/**

* CakePHP(tm) : Rapid Development Framework (http://cakephp.org)

* Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)

*

* Licensed under The MIT License

* For full copyright and license information, please see the LICENSE.txt

* Redistributions of files must retain the above copyright notice.

*

* @copyright Copyright (c) Cake Software Foundation, Inc. (http://cakefoundation.org)

* @link http://cakephp.org CakePHP(tm) Project

* @since 3.0.0

* @license http://www.opensource.org/licenses/mit-license.php MIT License

*/

namespace Cake\Database;

use Cake\Database\Expression\Comparison;

/**

* Sql dialect trait

*/

trait SqlDialectTrait

{

/**

* Quotes a database identifier (a column name, table name, etc..) to

* be used safely in queries without the risk of using reserved words

*

* @param string $identifier The identifier to quote.

* @return string

*/

public function quoteIdentifier($identifier)

{

$identifier = trim($identifier);

if ($identifier === '*') {

return '*';

}

if ($identifier === '') {

return '';

}

// string

if (preg_match('/^[\w-]+$/', $identifier)) {

return $this->_startQuote . $identifier . $this->_endQuote;

}

if (preg_match('/^[\w-]+\.[^ \*]*$/', $identifier)) {

// string.string

$items = explode('.', $identifier);

return $this->_startQuote . implode($this->_endQuote . '.' . $this->_startQuote, $items) . $this->_endQuote;

}

if (preg_match('/^[\w-]+\.\*$/', $identifier)) {

// string.*

return $this->_startQuote . str_replace('.*', $this->_endQuote . '.*', $identifier);

}

if (preg_match('/^([\w-]+)\((.*)\)$/', $identifier, $matches)) {

// Functions

return $matches[1] . '(' . $this->quoteIdentifier($matches[2]) . ')';

}

// Alias.field AS thing

if (preg_match('/^([\w-]+(\.[\w-]+|\(.*\))*)\s+AS\s*([\w-]+)$/i', $identifier, $matches)) {

return $this->quoteIdentifier($matches[1]) . ' AS ' . $this->quoteIdentifier($matches[3]);

}

if (preg_match('/^[\w-_\s]*[\w-_]+/', $identifier)) {

return $this->_startQuote . $identifier . $this->_endQuote;

}

return $identifier;

}

/**

* Returns a callable function that will be used to transform a passed Query object.

* This function, in turn, will return an instance of a Query object that has been

* transformed to accommodate any specificities of the SQL dialect in use.

*

* @param string $type the type of query to be transformed

* (select, insert, update, delete)

* @return callable

*/

public function queryTranslator($type)

{

return function ($query) use ($type) {

if ($this->autoQuoting()) {

$query = (new IdentifierQuoter($this))->quote($query);

}

$query = $this->{'_' . $type . 'QueryTranslator'}($query);

$translators = $this->_expressionTranslators();

if (!$translators) {

return $query;

}

$query->traverseExpressions(function ($expression) use ($translators, $query) {

foreach ($translators as $class => $method) {

if ($expression instanceof $class) {

$this->{$method}($expression, $query);

}

}

});

return $query;

};

}

/**

* Returns an associative array of methods that will transform Expression

* objects to conform with the specific SQL dialect. Keys are class names

* and values a method in this class.

*

* @return array

*/

protected function _expressionTranslators()

{

return [];

}

/**

* Apply translation steps to select queries.

*

* @param Query $query The query to translate

* @return Query The modified query

*/

protected function _selectQueryTranslator($query)

{

return $this->_transformDistinct($query);

}

/**

* Returns the passed query after rewriting the DISTINCT clause, so that drivers

* that do not support the "ON" part can provide the actual way it should be done

*

* @param Query $query The query to be transformed

* @return Query

*/

protected function _transformDistinct($query)

{

if (is_array($query->clause('distinct'))) {

$query->group($query->clause('distinct'), true);

$query->distinct(false);

}

return $query;

}

/**

* Apply translation steps to delete queries.

*

* Chops out aliases on delete query conditions as most database dialects do not

* support aliases in delete queries. This also removes aliases

* in table names as they frequently don't work either.

*

* We are intentionally not supporting deletes with joins as they have even poorer support.

*

* @param Query $query The query to translate

* @return Query The modified query

*/

protected function _deleteQueryTranslator($query)

{

$hadAlias = false;

$tables = [];

foreach ($query->clause('from') as $alias => $table) {

if (is_string($alias)) {

$hadAlias = true;

}

$tables[] = $table;

}

if ($hadAlias) {

$query->from($tables, true);

}

if (!$hadAlias) {

return $query;

}

$conditions = $query->clause('where');

if ($conditions) {

$conditions->traverse(function ($condition) {

if (!($condition instanceof Comparison)) {

return $condition;

}

$field = $condition->getField();

if (strpos($field, '.') !== false) {

list(, $field) = explode('.', $field);

$condition->setField($field);

}

return $condition;

});

}

return $query;

}

/**

* Apply translation steps to update queries.

*

* @param Query $query The query to translate

* @return Query The modified query

*/

protected function _updateQueryTranslator($query)

{

return $query;

}

/**

* Apply translation steps to insert queries.

*

* @param Query $query The query to translate

* @return Query The modified query

*/

protected function _insertQueryTranslator($query)

{

return $query;

}

/**

* Returns a SQL snippet for creating a new transaction savepoint

*

* @param string $name save point name

* @return string

*/

public function savePointSQL($name)

{

return 'SAVEPOINT LEVEL' . $name;

}

/**

* Returns a SQL snippet for releasing a previously created save point

*

* @param string $name save point name

* @return string

*/

public function releaseSavePointSQL($name)

{

return 'RELEASE SAVEPOINT LEVEL' . $name;

}

/**

* Returns a SQL snippet for rollbacking a previously created save point

*

* @param string $name save point name

* @return string

*/

public function rollbackSavePointSQL($name)

{

return 'ROLLBACK TO SAVEPOINT LEVEL' . $name;

}

}