From a519d01754f053eaa8301c5433c5a1c64a80d7f9 Mon Sep 17 00:00:00 2001
From: hallgren <hallgren@chalmers.se>
Date: Thu, 29 Mar 2012 14:11:38 +0000
Subject: [PATCH] gfse: show an informative error message in browsers that lack
 support for localStorage

---
 src/www/gfse/editor.js       | 10 +++++++---
 src/www/gfse/localstorage.js |  8 ++++++++
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/www/gfse/editor.js b/src/www/gfse/editor.js
index 4edc7f193..6e7d78cd5 100644
--- a/src/www/gfse/editor.js
+++ b/src/www/gfse/editor.js
@@ -1440,9 +1440,13 @@ function dir_bugfix() {
 }
 
 if(editor) {
-    initial_view();
-    touch_edit();
-    dir_bugfix();
+    if(supports_html5_storage()) {
+	initial_view();
+	touch_edit();
+	dir_bugfix();
+    }
+    else
+	editor.innerHTML="<p>This browser does not appear to support localStorage, and the grammar editor does not work without it. Sorry!"
 }
 
 //console.log("hi")
diff --git a/src/www/gfse/localstorage.js b/src/www/gfse/localstorage.js
index 696a432fb..162b1db3b 100644
--- a/src/www/gfse/localstorage.js
+++ b/src/www/gfse/localstorage.js
@@ -2,6 +2,14 @@
 // Grammars are stored locally in the browser using localStorage.
 // See http://diveintohtml5.info/storage.html
 
+function supports_html5_storage() {
+  try {
+    return 'localStorage' in window && window['localStorage'] !== null;
+  } catch (e) {
+    return false;
+  }
+}
+
 var local={
     prefix:"gf.editor.simple.grammar",
     get: function (name,def) {