Allow filtering to alerted messages with is:alerted

(imported from commit 99834f1ee1b9b2e0f5c7427afa1494bf404e3626)

static/js/filter.js

@@ -239,6 +239,10 @@ Filter.prototype = {
                         if (!message.mentioned) {
                             return false;
                         }
+                    } else if (operand === 'alerted') {
+                        if (!message.alerted) {
+                            return false;
+                        }
                     }
 
                     break;

static/js/search_suggestion.js

@@ -57,6 +57,8 @@ function describe(operators) {
                 return 'Narrow to starred messages';
             } else if (operand === 'mentioned') {
                 return 'Narrow to mentioned messages';
+            } else if (operand === 'alerted') {
+                return 'Narrow to alerted messages';
             }
             break;
 
@@ -367,6 +369,10 @@ function get_special_filter_suggestions(query, operators) {
             search_string: 'is:mentioned',
             description: '@-mentions'
         },
+        {
+            search_string: 'is:alerted',
+            description: 'Alerted messages'
+        },
         {
             search_string: 'sender:' + page_params.email,
             description: 'Sent by me'

static/js/zulip.js

@@ -552,6 +552,7 @@ function add_message_metadata(message) {
     message.mentioned = message.flags.indexOf("mentioned") !== -1 ||
                         message.flags.indexOf("wildcard_mentioned") !== -1;
     message.collapsed = message.flags.indexOf("collapsed") !== -1;
+    message.alerted = message.flags.indexOf("has_alert_word") !== -1;
 
     switch (message.type) {
     case 'stream':

zerver/tests/frontend/node/search_suggestion.js

@@ -150,6 +150,7 @@ set_global('narrow', {});
         "is:private",
         "is:starred",
         "is:mentioned",
+        "is:alerted",
         "sender:bob@zulip.com",
         "stream:devel",
         "stream:office"
@@ -164,6 +165,7 @@ set_global('narrow', {});
     assert.equal(describe('is:private'), 'Private messages');
     assert.equal(describe('is:starred'), 'Starred messages');
     assert.equal(describe('is:mentioned'), '@-mentions');
+    assert.equal(describe('is:alerted'), 'Alerted messages');
     assert.equal(describe('sender:bob@zulip.com'), 'Sent by me');
     assert.equal(describe('stream:devel'), 'Narrow to stream <strong>devel</strong>');
 }());

zerver/views/__init__.py

@@ -846,6 +846,8 @@ class NarrowBuilder(object):
             return Q(flags=UserMessage.flags.starred)
         elif operand == 'mentioned':
             return Q(flags=UserMessage.flags.mentioned)
+        elif operand == 'alerted':
+            return Q(flags=UserMessage.flags.mentioned)
         raise BadNarrowOperator("unknown 'is' operand " + operand)
 
     def by_stream(self, operand):