UnionQueryBuilder.php

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<?php
 
namespace Wikimedia\Rdbms;
 
use Wikimedia\Rdbms\Platform\ISQLPlatform;
 
class UnionQueryBuilder {
    public const SORT_ASC = 'ASC';
 
    public const SORT_DESC = 'DESC';
 
    private $sqbs = [];
 
    private $db;
 
    private $all = IReadableDatabase::UNION_DISTINCT;
 
    private $options = [];
 
    private $caller = __CLASS__;
 
    public function __construct( IDatabase $db ) {
        $this->db = $db;
    }
 
    public function add( SelectQueryBuilder $selectQueryBuilder ) {
        $this->sqbs[] = $selectQueryBuilder;
        return $this;
    }
 
    public function all() {
        $this->all = $this->db::UNION_ALL;
        return $this;
    }
 
    public function limit( $limit ) {
        if ( !$this->db->unionSupportsOrderAndLimit() ) {
            return $this;
        }
        $this->options['LIMIT'] = $limit;
        return $this;
    }
 
    public function offset( $offset ) {
        if ( !$this->db->unionSupportsOrderAndLimit() ) {
            return $this;
        }
        $this->options['OFFSET'] = $offset;
        return $this;
    }
 
    public function orderBy( $fields, $direction = null ) {
        if ( !$this->db->unionSupportsOrderAndLimit() ) {
            return $this;
        }
        if ( $direction === null ) {
            $this->mergeOption( 'ORDER BY', $fields );
        } elseif ( is_array( $fields ) ) {
            $fieldsWithDirection = [];
            foreach ( $fields as $field ) {
                $fieldsWithDirection[] = "$field $direction";
            }
            $this->mergeOption( 'ORDER BY', $fieldsWithDirection );
        } else {
            $this->mergeOption( 'ORDER BY', "$fields $direction" );
        }
        return $this;
    }
 
    private function mergeOption( $name, $newArrayOrValue ) {
        $value = isset( $this->options[$name] )
            ? (array)$this->options[$name] : [];
        if ( is_array( $newArrayOrValue ) ) {
            $value = array_merge( $value, $newArrayOrValue );
        } else {
            $value[] = $newArrayOrValue;
        }
        $this->options[$name] = $value;
    }
 
    public function caller( $fname ) {
        $this->caller = $fname;
        return $this;
    }
 
    public function fetchResultSet() {
        $query = new Query( $this->getSQL(), ISQLPlatform::QUERY_CHANGE_NONE, 'SELECT' );
        return $this->db->query( $query, $this->caller );
    }
 
    public function fetchField() {
        $this->limit( 1 );
        foreach ( $this->fetchResultSet() as $row ) {
            $row = (array)$row;
            if ( count( $row ) !== 1 ) {
                throw new \UnexpectedValueException(
                    __METHOD__ . ' expects the query to have only one field' );
            }
            return $row[ array_key_first( $row ) ];
        }
        return false;
    }
 
    public function fetchFieldValues() {
        $values = [];
        foreach ( $this->fetchResultSet() as $row ) {
            $row = (array)$row;
            if ( count( $row ) !== 1 ) {
                throw new \UnexpectedValueException(
                    __METHOD__ . ' expects the query to have only one field' );
            }
            $values[] = $row[ array_key_first( $row ) ];
        }
        return $values;
    }
 
    public function fetchRow() {
        $this->limit( 1 );
        foreach ( $this->fetchResultSet() as $row ) {
            return $row;
        }
        return false;
    }
 
    public function getSQL() {
        $sqls = [];
        foreach ( $this->sqbs as $sqb ) {
            $sqls[] = $sqb->getSQL();
        }
        return $this->db->unionQueries( $sqls, $this->all, $this->options );
    }
 
}