gistfile1.php

<?php
/**
 * @file
 * Contains \Drupal\Core\Database\Query\PlaceholderTrait.
 */

namespace Drupal\Core\Database\Query;

/**
 * @see \Drupal\Core\Database\Query\PlaceholderInterface
 */
trait PlaceholderTrait {

  /**
   * A unique identifier for this query object.
   */
  protected $uniqueIdentifier;

  /**
   * The placeholder counter.
   */
  protected $placeholder = 0;

  /**
   * Implements \Drupal\Core\Database\Query\PlaceholderInterface::uniqueIdentifier().
   */
  public function uniqueIdentifier() {
    if (!isset($this->uniqueIdentifier)) {
      $this->uniqueIdentifier = uniqid('', TRUE);
    }
    return $this->uniqueIdentifier;
  }

  /**
   * {@inheritdoc}
   */
  public function nextPlaceholder() {
    return $this->placeholder++;
  }

}