Menus: Add white space option to `wp_nav_menu()` and `wp_list_pages()`.

Adds an `item_spacing` option to the arguments array for the functions `wp_nav_menu()`, `wp_list_pages()`, and `wp_page_menu()`. `item_spacing` is a boolean accepting either `preserve` or `discard`.

Previously, certain CSS choices could result in a site's layout changing if `wp_nav_menu()` fell back to the default `wp_list_pages()` due to differences in the whitespace within the HTML. The new argument ensures a function outputs consistant HTML while maintaining backward compatibility.

Fixes #35206.

Built from https://develop.svn.wordpress.org/trunk@38523


git-svn-id: http://core.svn.wordpress.org/trunk@38464 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-walker-nav-menu.php

@@ -50,8 +50,15 @@ class Walker_Nav_Menu extends Walker {
 	 * @param array  $args   An array of wp_nav_menu() arguments.
 	 */
 	public function start_lvl( &$output, $depth = 0, $args = array() ) {
-		$indent = str_repeat("\t", $depth);
+		if ( 'preserve' === $args->item_spacing ) {
-		$output .= "\n$indent<ul class=\"sub-menu\">\n";
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
+		$indent = str_repeat( $t, $depth );
+		$output .= "{$n}{$indent}<ul class=\"sub-menu\">{$n}";
 	}
 
 	/**
@@ -66,8 +73,15 @@ class Walker_Nav_Menu extends Walker {
 	 * @param array  $args   An array of wp_nav_menu() arguments.
 	 */
 	public function end_lvl( &$output, $depth = 0, $args = array() ) {
-		$indent = str_repeat("\t", $depth);
+		if ( 'preserve' === $args->item_spacing ) {
-		$output .= "$indent</ul>\n";
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
+		$indent = str_repeat( $t, $depth );
+		$output .= "$indent</ul>{$n}";
 	}
 
 	/**
@@ -85,7 +99,14 @@ class Walker_Nav_Menu extends Walker {
 	 * @param int    $id     Current item ID.
 	 */
 	public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
-		$indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';
+		if ( 'preserve' === $args->item_spacing ) {
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
+		$indent = ( $depth ) ? str_repeat( $t, $depth ) : '';
 
 		$classes = empty( $item->classes ) ? array() : (array) $item->classes;
 		$classes[] = 'menu-item-' . $item->ID;
@@ -216,7 +237,14 @@ class Walker_Nav_Menu extends Walker {
 	 * @param array  $args   An array of wp_nav_menu() arguments.
 	 */
 	public function end_el( &$output, $item, $depth = 0, $args = array() ) {
-		$output .= "</li>\n";
+		if ( 'preserve' === $args->item_spacing ) {
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
+		$output .= "</li>{$n}";
 	}
 
 } // Walker_Nav_Menu

wp-includes/class-walker-page.php

@@ -53,8 +53,15 @@ class Walker_Page extends Walker {
 	 *                       Default empty array.
 	 */
 	public function start_lvl( &$output, $depth = 0, $args = array() ) {
-		$indent = str_repeat("\t", $depth);
+		if ( 'preserve' === $args['item_spacing'] ) {
-		$output .= "\n$indent<ul class='children'>\n";
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
+		$indent = str_repeat( $t, $depth );
+		$output .= "{$n}{$indent}<ul class='children'>{$n}";
 	}
 
 	/**
@@ -71,8 +78,15 @@ class Walker_Page extends Walker {
 	 *                       Default empty array.
 	 */
 	public function end_lvl( &$output, $depth = 0, $args = array() ) {
-		$indent = str_repeat("\t", $depth);
+		if ( 'preserve' === $args['item_spacing'] ) {
-		$output .= "$indent</ul>\n";
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
+		$indent = str_repeat( $t, $depth );
+		$output .= "{$indent}</ul>{$n}";
 	}
 
 	/**
@@ -89,8 +103,15 @@ class Walker_Page extends Walker {
 	 * @param int     $current_page Optional. Page ID. Default 0.
 	 */
 	public function start_el( &$output, $page, $depth = 0, $args = array(), $current_page = 0 ) {
+		if ( 'preserve' === $args['item_spacing'] ) {
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
 		if ( $depth ) {
-			$indent = str_repeat( "\t", $depth );
+			$indent = str_repeat( $t, $depth );
 		} else {
 			$indent = '';
 		}
@@ -175,7 +196,14 @@ class Walker_Page extends Walker {
 	 * @param array   $args   Optional. Array of arguments. Default empty array.
 	 */
 	public function end_el( &$output, $page, $depth = 0, $args = array() ) {
-		$output .= "</li>\n";
+		if ( 'preserve' === $args['item_spacing'] ) {
+			$t = "\t";
+			$n = "\n";
+		} else {
+			$t = '';
+			$n = '';
+		}
+		$output .= "</li>{$n}";
 	}
 
 }

wp-includes/nav-menu-template.php

@@ -40,6 +40,7 @@ require_once ABSPATH . WPINC . '/class-walker-nav-menu.php';
  *                                               in order to be selectable by the user.
  *     @type string             $items_wrap      How the list items should be wrapped. Default is a ul with an id and class.
  *                                               Uses printf() format with numbered placeholders.
+ *     @type string             $item_spacing    Whether whitespace format the menu's HTML: 'discard' or 'preserve' (default).
  * }
  * @return object|false|void Menu output if $echo is false, false if there are no items or no menu was found.
  */
@@ -47,10 +48,16 @@ function wp_nav_menu( $args = array() ) {
 	static $menu_id_slugs = array();
 
 	$defaults = array( 'menu' => '', 'container' => 'div', 'container_class' => '', 'container_id' => '', 'menu_class' => 'menu', 'menu_id' => '',
-	'echo' => true, 'fallback_cb' => 'wp_page_menu', 'before' => '', 'after' => '', 'link_before' => '', 'link_after' => '', 'items_wrap' => '<ul id="%1$s" class="%2$s">%3$s</ul>',
+	'echo' => true, 'fallback_cb' => 'wp_page_menu', 'before' => '', 'after' => '', 'link_before' => '', 'link_after' => '', 'items_wrap' => '<ul id="%1$s" class="%2$s">%3$s</ul>', 'item_spacing' => 'preserve',
 	'depth' => 0, 'walker' => '', 'theme_location' => '' );
 
 	$args = wp_parse_args( $args, $defaults );
+
+	if ( ! in_array( $args['item_spacing'], array( 'preserve', 'discard' ), true ) ) {
+		// invalid value, fall back to default.
+		$args['item_spacing'] = $defaults['item_spacing'];
+	}
+
 	/**
 	 * Filters the arguments used to display a navigation menu.
 	 *

wp-includes/post-template.php

@@ -1138,6 +1138,7 @@ function wp_dropdown_pages( $args = '' ) {
  *                                'menu_order', 'post_parent', 'ID', 'rand', or 'comment_count'. Default 'post_title'.
  *     @type string $title_li     List heading. Passing a null or empty value will result in no heading, and the list
  *                                will not be wrapped with unordered list `<ul>` tags. Default 'Pages'.
+ *     @type string $item_spacing Whether whitespace format the menu's HTML: 'discard' or 'preserve' (default).
  *     @type Walker $walker       Walker instance to use for listing pages. Default empty (Walker_Page).
  * }
  * @return string|void HTML list of pages.
@@ -1149,11 +1150,16 @@ function wp_list_pages( $args = '' ) {
 		'child_of' => 0, 'exclude' => '',
 		'title_li' => __( 'Pages' ), 'echo' => 1,
 		'authors' => '', 'sort_column' => 'menu_order, post_title',
-		'link_before' => '', 'link_after' => '', 'walker' => '',
+		'link_before' => '', 'link_after' => '', 'item_spacing' => 'preserve', 'walker' => '',
 	);
 
 	$r = wp_parse_args( $args, $defaults );
 
+	if ( ! in_array( $r['item_spacing'], array( 'preserve', 'discard' ), true ) ) {
+		// invalid value, fall back to default.
+		$r['item_spacing'] = $defaults['item_spacing'];
+	}
+
 	$output = '';
 	$current_page = 0;
 
@@ -1243,6 +1249,7 @@ function wp_list_pages( $args = '' ) {
  *     @type string          $link_after   The HTML or text to append to $show_home text. Default empty.
  *     @type string          $before       The HTML or text to prepend to the menu. Default is '<ul>'.
  *     @type string          $after        The HTML or text to append to the menu. Default is '</ul>'.
+ *     @type string          $item_spacing Whether whitespace format the menu's HTML: 'discard' or 'preserve' (default).
  *     @type Walker          $walker       Walker instance to use for listing pages. Default empty (Walker_Page).
  * }
  * @return string|void HTML menu
@@ -1258,10 +1265,24 @@ function wp_page_menu( $args = array() ) {
 		'link_after'   => '',
 		'before'       => '<ul>',
 		'after'        => '</ul>',
+		'item_spacing' => 'discard',
 		'walker'       => '',
 	);
 	$args = wp_parse_args( $args, $defaults );
 
+	if ( ! in_array( $args['item_spacing'], array( 'preserve', 'discard' ) ) ) {
+		// invalid value, fall back to default.
+		$args['item_spacing'] = $defaults['item_spacing'];
+	}
+
+	if ( 'preserve' === $args['item_spacing'] ) {
+		$t = "\t";
+		$n = "\n";
+	} else {
+		$t = '';
+		$n = '';
+	}
+
 	/**
 	 * Filters the arguments used to generate a page-based menu.
 	 *
@@ -1300,7 +1321,7 @@ function wp_page_menu( $args = array() ) {
 
 	$list_args['echo'] = false;
 	$list_args['title_li'] = '';
-	$menu .= str_replace( array( "\r", "\n", "\t" ), '', wp_list_pages($list_args) );
+	$menu .= wp_list_pages( $list_args );
 
 	$container = sanitize_text_field( $args['container'] );
 
@@ -1315,7 +1336,7 @@ function wp_page_menu( $args = array() ) {
 		if ( isset( $args['fallback_cb'] ) &&
 			'wp_page_menu' === $args['fallback_cb'] &&
 			'ul' !== $container ) {
-			$args['before'] = '<ul>';
+			$args['before'] = "<ul>{$n}";
 			$args['after'] = '</ul>';
 		}
 
@@ -1331,7 +1352,7 @@ function wp_page_menu( $args = array() ) {
 		$attrs .= ' class="' . esc_attr( $args['menu_class'] ) . '"';
 	}
 
-	$menu = "<{$container}{$attrs}>" . $menu . "</{$container}>\n";
+	$menu = "<{$container}{$attrs}>" . $menu . "</{$container}>{$n}";
 
 	/**
 	 * Filters the HTML output of a page-based menu.

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-alpha-38522';
+$wp_version = '4.7-alpha-38523';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.