From 408dba191050487c6320523b9130e0a265a948d5 Mon Sep 17 00:00:00 2001
From: John Foerch <jjfoerch@earthlink.net>
Date: Wed, 13 Oct 2010 20:05:23 -0400
Subject: [PATCH] read_browser_object: throw error when there is no object to
 read

As of this patch, null is officially defined as a valid browser object.
All commands which call read_browser_object must supply a default via
the $browser_object keyword.  The commands 'scroll' and 'reload' have
been updated to supply a default of null.  The interactive error
"No browser object" is thrown when the interactive context's browser
object is 'undefined'.
---
 modules/content-buffer.js | 3 ++-
 modules/element.js        | 3 +++
 modules/input.js          | 2 +-
 modules/interactive.js    | 8 ++++----
 modules/scroll.js         | 3 ++-
 5 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/modules/content-buffer.js b/modules/content-buffer.js
index dab886d..46ece7b 100644
--- a/modules/content-buffer.js
+++ b/modules/content-buffer.js
@@ -572,7 +572,8 @@ interactive("reload",
         check_buffer(I.buffer, content_buffer);
         var element = yield read_browser_object(I);
         reload(I.buffer, I.P, element, I.forced_charset);
-    });
+    },
+    $browser_object = null);
 
 /**
  * browserDOMWindow: intercept window opening
diff --git a/modules/element.js b/modules/element.js
index a3d8b3e..b0891aa 100644
--- a/modules/element.js
+++ b/modules/element.js
@@ -286,6 +286,9 @@ interactive("browser-object-text",
 
 function read_browser_object (I) {
     var browser_object = I.browser_object;
+    if (browser_object === undefined)
+        throw interactive_error("No browser object");
+
     var result;
     // literals cannot be overridden
     if (browser_object instanceof Function) {
diff --git a/modules/input.js b/modules/input.js
index dc78a7f..ccfd080 100644
--- a/modules/input.js
+++ b/modules/input.js
@@ -221,7 +221,7 @@ sequence:
                     event_kill(event);
 
                 if (binding) {
-                    if (binding.browser_object != null)
+                    if (binding.browser_object !== undefined)
                         I.binding_browser_object = binding.browser_object;
                     if (binding.constructor == Array) {
                         keymaps = binding;
diff --git a/modules/interactive.js b/modules/interactive.js
index a6e6988..a44238c 100644
--- a/modules/interactive.js
+++ b/modules/interactive.js
@@ -108,21 +108,21 @@ function call_interactively (I, command) {
 
     // if there was no interactive browser-object,
     // binding_browser_object becomes the default.
-    if (I.browser_object == null) {
+    if (I.browser_object === undefined) {
         I.browser_object = I.binding_browser_object;
     }
     // if the command's default browser object is a non-null literal,
     // it overrides an interactive browser-object, but not a binding
     // browser object.
-    if (cmd.browser_object != null &&
+    if (cmd.browser_object !== undefined &&
         (! (cmd.browser_object instanceof browser_object_class)) &&
-        (I.binding_browser_object == null))
+        (I.binding_browser_object === undefined))
     {
         I.browser_object = cmd.browser_object;
     }
     // if we still have no browser-object, look for a page-mode
     // default, or finally the command default.
-    if (I.browser_object == null) {
+    if (I.browser_object === undefined) {
         I.browser_object =
             (I.buffer && I.buffer.default_browser_object_classes[command]) ||
             cmd.browser_object;
diff --git a/modules/scroll.js b/modules/scroll.js
index a07d470..ad00199 100644
--- a/modules/scroll.js
+++ b/modules/scroll.js
@@ -93,6 +93,7 @@ interactive("scroll",
     "the object passed to the command as a browser-object.  If the object "+
     "is a DOM node, that node will be scrolled to the top of the viewport "+
     "if possible.",
-    scroll);
+    scroll,
+    $browser_object = null);
 
 provide("scroll");
-- 
2.11.4.GIT