WordPress/wp-includes/post.php

<?php
/**
 * Core Post API
 *
 * @package WordPress
 * @subpackage Post
 * @since 1.5.0
 */

/** Core posts functionality */
require_once( ABSPATH . WPINC . '/post-functions.php' );

/** Walker_Page class */
require_once( ABSPATH . WPINC . '/class-walker-page.php' );

/** Walker_PageDropdown class */
require_once( ABSPATH . WPINC . '/class-walker-page-dropdown.php' );

/** WP_Post class */
require_once( ABSPATH . WPINC . '/class-wp-post.php' );