WP_Query::setup_postdata( WP_Post|object|int $post )

	public function setup_postdata( $post ) {
		global $id, $authordata, $currentday, $currentmonth, $page, $pages, $multipage, $more, $numpages;

		if ( ! ( $post instanceof WP_Post ) ) {
			$post = get_post( $post );
		}

		if ( ! $post ) {
			return;
		}

		$id = (int) $post->ID;

		$authordata = get_userdata($post->post_author);

		$currentday = mysql2date('d.m.y', $post->post_date, false);
		$currentmonth = mysql2date('m', $post->post_date, false);
		$numpages = 1;
		$multipage = 0;
		$page = $this->get( 'page' );
		if ( ! $page )
			$page = 1;

		/*
		 * Force full post content when viewing the permalink for the $post,
		 * or when on an RSS feed. Otherwise respect the 'more' tag.
		 */
		if ( $post->ID === get_queried_object_id() && ( $this->is_page() || $this->is_single() ) ) {
			$more = 1;
		} elseif ( $this->is_feed() ) {
			$more = 1;
		} else {
			$more = 0;
		}

		$content = $post->post_content;
		if ( false !== strpos( $content, '<!--nextpage-->' ) ) {
			$content = str_replace( "\n<!--nextpage-->\n", '<!--nextpage-->', $content );
			$content = str_replace( "\n<!--nextpage-->", '<!--nextpage-->', $content );
			$content = str_replace( "<!--nextpage-->\n", '<!--nextpage-->', $content );

			// Ignore nextpage at the beginning of the content.
			if ( 0 === strpos( $content, '<!--nextpage-->' ) )
				$content = substr( $content, 15 );

			$pages = explode('<!--nextpage-->', $content);
		} else {
			$pages = array( $post->post_content );
		}

		/**
		 * Filters the "pages" derived from splitting the post content.
		 *
		 * "Pages" are determined by splitting the post content based on the presence
		 * of `<!-- nextpage -->` tags.
		 *
		 * @since WP-4.4.0
		 *
		 * @param array   $pages Array of "pages" derived from the post content.
		 *                       of `<!-- nextpage -->` tags..
		 * @param WP_Post $post  Current post object.
		 */
		$pages = apply_filters( 'content_pagination', $pages, $post );

		$numpages = count( $pages );

		if ( $numpages > 1 ) {
			if ( $page > 1 ) {
				$more = 1;
			}
			$multipage = 1;
		} else {
	 		$multipage = 0;
	 	}

		/**
		 * Fires once the post data has been setup.
		 *
		 * @since WP-2.8.0
		 * @since WP-4.1.0 Introduced `$this` parameter.
		 *
		 * @param WP_Post  $post The Post object (passed by reference).
		 * @param WP_Query $this The current Query object (passed by reference).
		 */
		do_action_ref_array( 'the_post', array( &$post, &$this ) );

		return true;
	}