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<?php

/**
 * The Gravity Forms Query Series class.
 *
 * A list of arguments. Would have named "List" but it's a reserved keyword.
 */
class GF_Query_Series {
    /**
     * @var array A series of values.
     */
    private $_values = array();

    /**
     * A series of expressions.
     *
     * @param mixed[] $values With a valid expression type (GF_Query_Literal, GF_Query_Column, GF_Query_Call)
     */
    public function __construct( $values ) {
        if ( is_array( $values ) ) {
            $this->_values = array_filter( $values, array( 'GF_Query_Condition', 'is_valid_expression_type' ) );
        }
    }

    /**
     * Get SQL for this.
     *
     * @param GF_Query $query     The query.
     * @param string           $delimiter The delimiter to stick the series values with.
     *
     * @return string The SQL.
     */
    public function sql( $query, $delimiter = '' ) {
        $values = array();

        foreach( $this->_values as $value ) {
            $values[] = $value->sql( $query );
        }

        $chunks = array_filter( $values, 'strlen' );

        return implode( $delimiter, $chunks);
    }

    /**
     * Proxy read-only values.
     */
    public function __get( $key ) {
        switch ( $key ):
            case 'values':
                return $this->_values;
        endswitch;
    }
}