<?php

/*

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE

 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 *

 * This software consists of voluntary contributions made by many individuals

 * and is licensed under the LGPL. For more information, see

 * <http://www.doctrine-project.org>.

 */

namespace Doctrine\DBAL\Query\Expression;

use Doctrine\DBAL\Connection;

/**

 * ExpressionBuilder class is responsible to dynamically create SQL query parts.

 *

 * @license     http://www.opensource.org/licenses/lgpl-license.php LGPL

 * @link        www.doctrine-project.com

 * @since       2.1

 * @author      Guilherme Blanco <guilhermeblanco@hotmail.com>

 * @author      Benjamin Eberlei <kontakt@beberlei.de>

 */

class ExpressionBuilder

{

    const EQ  = '=';

    const NEQ = '<>';

    const LT  = '<';

    const LTE = '<=';

    const GT  = '>';

    const GTE = '>=';

    /**

     * @var Doctrine\DBAL\Connection DBAL Connection

     */

    private $connection = null;

    /**

     * Initializes a new <tt>ExpressionBuilder</tt>.

     *

     * @param Doctrine\DBAL\Connection $connection DBAL Connection

     */

    public function __construct(Connection $connection)

    {

        $this->connection = $connection;

    }

    /**

     * Creates a conjunction of the given boolean expressions.

     *

     * Example:

     *

     *     [php]

     *     // (u.type = ?) AND (u.role = ?)

     *     $expr->andX('u.type = ?', 'u.role = ?'));

     *

     * @param mixed $x Optional clause. Defaults = null, but requires

     *                 at least one defined when converting to string.

     * @return CompositeExpression

     */

    public function andX($x = null)

    {

        return new CompositeExpression(CompositeExpression::TYPE_AND, func_get_args());

    }

    /**

     * Creates a disjunction of the given boolean expressions.

     *

     * Example:

     *

     *     [php]

     *     // (u.type = ?) OR (u.role = ?)

     *     $qb->where($qb->expr()->orX('u.type = ?', 'u.role = ?'));

     *

     * @param mixed $x Optional clause. Defaults = null, but requires

     *                 at least one defined when converting to string.

     * @return CompositeExpression

     */

    public function orX($x = null)

    {

        return new CompositeExpression(CompositeExpression::TYPE_OR, func_get_args());

    }

    /**

     * Creates a comparison expression.

     * 

     * @param mixed $x Left expression

     * @param string $operator One of the ExpressionBuikder::* constants.

     * @param mixed $y Right expression

     * @return string

     */

    public function comparison($x, $operator, $y)

    {

        return $x . ' ' . $operator . ' ' . $y;

    }

    /**

     * Creates an equality comparison expression with the given arguments.

     *

     * First argument is considered the left expression and the second is the right expression.

     * When converted to string, it will generated a <left expr> = <right expr>. Example:

     *

     *     [php]

     *     // u.id = ?

     *     $expr->eq('u.id', '?');

     *

     * @param mixed $x Left expression

     * @param mixed $y Right expression

     * @return string

     */

    public function eq($x, $y)

    {

        return $this->comparison($x, self::EQ, $y);

    }

    /**

     * Creates a non equality comparison expression with the given arguments.

     * First argument is considered the left expression and the second is the right expression.

     * When converted to string, it will generated a <left expr> <> <right expr>. Example:

     *

     *     [php]

     *     // u.id <> 1

     *     $q->where($q->expr()->neq('u.id', '1'));

     *

     * @param mixed $x Left expression

     * @param mixed $y Right expression

     * @return string

     */

    public function neq($x, $y)

    {

        return $this->comparison($x, self::NEQ, $y);

    }

    /**

     * Creates a lower-than comparison expression with the given arguments.

     * First argument is considered the left expression and the second is the right expression.

     * When converted to string, it will generated a <left expr> < <right expr>. Example:

     *

     *     [php]

     *     // u.id < ?

     *     $q->where($q->expr()->lt('u.id', '?'));

     *

     * @param mixed $x Left expression

     * @param mixed $y Right expression

     * @return string

     */

    public function lt($x, $y)

    {

        return $this->comparison($x, self::LT, $y);

    }

    /**

     * Creates a lower-than-equal comparison expression with the given arguments.

     * First argument is considered the left expression and the second is the right expression.

     * When converted to string, it will generated a <left expr> <= <right expr>. Example:

     *

     *     [php]

     *     // u.id <= ?

     *     $q->where($q->expr()->lte('u.id', '?'));

     *

     * @param mixed $x Left expression

     * @param mixed $y Right expression

     * @return string

     */

    public function lte($x, $y)

    {

        return $this->comparison($x, self::LTE, $y);

    }

    /**

     * Creates a greater-than comparison expression with the given arguments.

     * First argument is considered the left expression and the second is the right expression.

     * When converted to string, it will generated a <left expr> > <right expr>. Example:

     *

     *     [php]

     *     // u.id > ?

     *     $q->where($q->expr()->gt('u.id', '?'));

     *

     * @param mixed $x Left expression

     * @param mixed $y Right expression

     * @return string

     */

    public function gt($x, $y)

    {

        return $this->comparison($x, self::GT, $y);

    }

    /**

     * Creates a greater-than-equal comparison expression with the given arguments.

     * First argument is considered the left expression and the second is the right expression.

     * When converted to string, it will generated a <left expr> >= <right expr>. Example:

     *

     *     [php]

     *     // u.id >= ?

     *     $q->where($q->expr()->gte('u.id', '?'));

     *

     * @param mixed $x Left expression

     * @param mixed $y Right expression

     * @return string

     */

    public function gte($x, $y)

    {

        return $this->comparison($x, self::GTE, $y);

    }

    /**

     * Creates an IS NULL expression with the given arguments.

     *

     * @param string $x Field in string format to be restricted by IS NULL

     * 

     * @return string

     */

    public function isNull($x)

    {

        return $x . ' IS NULL';

    }

    /**

     * Creates an IS NOT NULL expression with the given arguments.

     *

     * @param string $x Field in string format to be restricted by IS NOT NULL

     * 

     * @return string

     */

    public function isNotNull($x)

    {

        return $x . ' IS NOT NULL';

    }

    /**

     * Creates a LIKE() comparison expression with the given arguments.

     *

     * @param string $x Field in string format to be inspected by LIKE() comparison.

     * @param mixed $y Argument to be used in LIKE() comparison.

     * 

     * @return string

     */

    public function like($x, $y)

    {

        return $this->comparison($x, 'LIKE', $y);

    }

    /**

     * Quotes a given input parameter.

     * 

     * @param mixed $input Parameter to be quoted.

     * @param string $type Type of the parameter.

     * 

     * @return string

     */

    public function literal($input, $type = null)

    {

        return $this->connection->quote($input, $type);

    }

}