Sort streams and subjects in a better way.

Modify the Bootstrap default sorter to sort by:
1. Starts-with, in a case-sensitive way
2. Starts-with, in a case-insensitive way
3. Matches anywhere, case-sensitive
4. Matches anywhere, case-insensitive

(This fixes the Keegan-reported issue of "Testing!" taking precedence
over "test" when he types in "tes")

(imported from commit b2a0127956fe7a8bf1cbf30752a6ddc2c49b7198)

zephyr/static/js/composebox_typeahead.js

@@ -113,7 +113,8 @@ exports.initialize = function () {
             return stream_list;
         },
         items: 3,
-        highlighter: composebox_typeahead_highlighter
+        highlighter: composebox_typeahead_highlighter,
+        sorter: typeahead_helper.sort_streams
     });
 
     $( "#subject" ).typeahead({
@@ -125,7 +126,8 @@ exports.initialize = function () {
             return [];
         },
         items: 3,
-        highlighter: composebox_typeahead_highlighter
+        highlighter: composebox_typeahead_highlighter,
+        sorter: typeahead_helper.sort_subjects
     });
 
     $( "#private_message_recipient" ).typeahead({

zephyr/static/js/typeahead_helper.js

@@ -82,6 +82,44 @@ exports.update_your_recipients = function (recipients) {
     });
 };
 
+exports.sorter = function (query, objs, get_item) {
+    // Based on Bootstrap typeahead's default sorter, but taking into
+    // account case sensitivity on "begins with"
+    var beginswithCaseSensitive = [];
+    var beginswithCaseInsensitive = [];
+    var caseSensitive = [];
+    var caseInsensitive = [];
+
+    var obj = objs.shift();
+    while (obj) {
+        var item = get_item(obj);
+        if (item.indexOf(query) === 0)
+            beginswithCaseSensitive.push(obj);
+        else if (item.toLowerCase().indexOf(query.toLowerCase()) !== -1)
+            beginswithCaseInsensitive.push(obj);
+        else if (item.indexOf(query) !== -1)
+            caseSensitive.push(obj);
+        else
+            caseInsensitive.push(obj);
+        obj = objs.shift();
+    }
+    return beginswithCaseSensitive.concat(beginswithCaseInsensitive,
+                                          caseSensitive,
+                                          caseInsensitive);
+};
+
+function identity(item) {
+    return item;
+}
+
+exports.sort_streams = function (items) {
+    return typeahead_helper.sorter(this.query, items, identity);
+};
+
+exports.sort_subjects = function (items) {
+    return typeahead_helper.sorter(this.query, items, identity);
+};
+
 return exports;
 
 }());