From 04ac4c64c9634d9f81035ff7e9db537f39b42f3c Mon Sep 17 00:00:00 2001
From: Stephen Blott
Date: Wed, 7 Jan 2015 09:57:03 +0000
Subject: Modes; rework Singletons, InsertModeBlocker and HandlerStack.

This begins work on addressing @philc's comments in #1413.  That work is
nevertheless not yet complete.
---
 content_scripts/mode.coffee | 12 ++++++++++++
 1 file changed, 12 insertions(+)

(limited to 'content_scripts/mode.coffee')

diff --git a/content_scripts/mode.coffee b/content_scripts/mode.coffee
index ff75460f..e9a4a621 100644
--- a/content_scripts/mode.coffee
+++ b/content_scripts/mode.coffee
@@ -75,6 +75,7 @@ class Mode
       keyup: @keyup
       updateBadge: (badge) => @alwaysContinueBubbling => @chooseBadge badge
 
+    @registerSingleton options.singleton if options.singleton
     Mode.updateBadge() if @badge
 
   push: (handlers) ->
@@ -116,6 +117,17 @@ class Mode
     func()
     mode.exit()
 
+  # Some modes are singletons: there may be at most one instance active at any one time.  A mode is a
+  # singleton if options.singleton is truthy.  The value of options.singleton should be the key which is
+  # required to be unique.  See PostFindMode for an example.
+  @singletons: {}
+  registerSingleton: (singleton) ->
+    singletons = Mode.singletons
+    singletons[singleton].exit() if singletons[singleton]
+    singletons[singleton] = @
+    @onExit =>
+      delete singletons[singleton] if singletons[singleton] == @
+
 # A SingletonMode is a Mode of which there may be at most one instance (of @singleton) active at any one time.
 # New instances cancel previously-active instances on startup.
 class SingletonMode extends Mode
-- 
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