StatementEmpty.php

<?php

namespace Drupal\Core\Database;


/**
 * Empty implementation of a database statement.
 *
 * This class satisfies the requirements of being a database statement/result
 * object, but does not actually contain data.  It is useful when developers
 * need to safely return an "empty" result set without connecting to an actual
 * database.  Calling code can then treat it the same as if it were an actual
 * result set that happens to contain no records.
 *
 * @see \Drupal\search\SearchQuery
 */
class StatementEmpty implements \Iterator, StatementInterface {
    
    /**
     * Is rowCount() execution allowed.
     *
     * @var bool
     */
    public $allowRowCount = FALSE;
    
    /**
     * {@inheritdoc}
     */
    public function execute($args = [], $options = []) {
        return FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getQueryString() {
        return '';
    }
    
    /**
     * {@inheritdoc}
     */
    public function rowCount() {
        if ($this->allowRowCount) {
            return 0;
        }
        throw new RowCountException();
    }
    
    /**
     * {@inheritdoc}
     */
    public function setFetchMode($mode, $a1 = NULL, $a2 = []) {
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetch($mode = NULL, $cursor_orientation = NULL, $cursor_offset = NULL) {
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchField($index = 0) {
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchObject() {
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAssoc() {
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAll($mode = NULL, $column_index = NULL, $constructor_arguments = NULL) {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchCol($index = 0) {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAllKeyed($key_index = 0, $value_index = 1) {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function fetchAllAssoc($key, $fetch = NULL) {
        return [];
    }
    
    /**
     * {@inheritdoc}
     */
    public function current() {
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function key() {
        return NULL;
    }
    
    /**
     * {@inheritdoc}
     */
    public function rewind() {
        // Nothing to do: our DatabaseStatement can't be rewound.
    }
    
    /**
     * {@inheritdoc}
     */
    public function next() {
        // Do nothing, since this is an always-empty implementation.
    }
    
    /**
     * {@inheritdoc}
     */
    public function valid() {
        return FALSE;
    }

}