Simplify marker events

Instead of marker-added and marker-removed events which are emitted
when markers are created/invalidated/revalidated/destroyed, we now
just have marker-created events that are triggered *only* when markers
are created for the first time. The marker itself emits a 'destroyed'
event when it is destroyed. The marker already notifies observers when
its validation status changes, so that's covered.

spec/app/display-buffer-spec.coffee

@@ -525,6 +525,16 @@ describe "DisplayBuffer", ->
         expect(marker1.getBufferRange()).toEqual [[8, 4], [8, 10]]
         expect(marker2.getScreenRange()).toEqual [[5, 4], [5, 10]]
 
+      it "emits a 'marker-created' event on the DisplayBuffer whenever a marker is created", ->
+        displayBuffer.on 'marker-created', markerCreatedHandler = jasmine.createSpy("markerCreatedHandler")
+
+        marker1 = displayBuffer.markScreenRange([[5, 4], [5, 10]])
+        expect(markerCreatedHandler).toHaveBeenCalledWith(marker1)
+        markerCreatedHandler.reset()
+
+        marker2 = buffer.markRange([[5, 4], [5, 10]])
+        expect(markerCreatedHandler).toHaveBeenCalledWith(displayBuffer.getMarker(marker2.id))
+
       it "allows marker head and tail positions to be manipulated in both screen and buffer coordinates", ->
         marker = displayBuffer.markScreenRange([[5, 4], [5, 10]])
         marker.setHeadScreenPosition([5, 4])
@@ -737,22 +747,3 @@ describe "DisplayBuffer", ->
         marker.destroy()
         expect(marker.isValid()).toBeFalsy()
         expect(displayBuffer.getMarker(marker.id)).toBeUndefined()
-
-    describe "marker-added and marker-removed events", ->
-      it "emits the appropriate event when a marker is created, destroyed, or its validity changes", ->
-        displayBuffer.on 'marker-added', markerAddedHandler = jasmine.createSpy("markerAddedHandler")
-        displayBuffer.on 'marker-removed', markerRemovedHandler = jasmine.createSpy("markerRemovedHandler")
-
-        marker = displayBuffer.markBufferRange([[5, 4], [5, 10]])
-        expect(markerAddedHandler).toHaveBeenCalledWith(marker)
-        markerAddedHandler.reset()
-
-        buffer.change([[5, 3], [5, 11]], 'hey')
-        expect(markerRemovedHandler).toHaveBeenCalledWith(marker)
-        markerRemovedHandler.reset()
-
-        buffer.undo()
-        expect(markerAddedHandler).toHaveBeenCalledWith(marker)
-
-        marker.destroy()
-        expect(markerRemovedHandler).toHaveBeenCalledWith(marker)

spec/app/text-buffer-spec.coffee

@@ -781,11 +781,10 @@ describe 'Buffer', ->
         expect(buffer.positionForCharacterIndex(20)).toEqual [3, 0]
 
   describe "markers", ->
-    [markerAddedHandler, markerRemovedHandler] = []
+    markerCreatedHandler = null
 
     beforeEach ->
-      buffer.on('marker-added', markerAddedHandler = jasmine.createSpy("markerAddedHandler"))
-      buffer.on('marker-removed', markerRemovedHandler = jasmine.createSpy("markerRemovedHandler"))
+      buffer.on('marker-created', markerCreatedHandler = jasmine.createSpy("markerCreatedHandler"))
 
     describe "marker creation", ->
       it "allows markers to be created with ranges and positions", ->
@@ -806,9 +805,9 @@ describe 'Buffer', ->
         expect(marker.getHeadPosition()).toEqual [4, 20]
         expect(marker.getTailPosition()).toEqual [4, 23]
 
-      it "emits the 'marker-added' event when markers are created", ->
+      it "emits the 'marker-created' event when markers are created", ->
         marker = buffer.markRange([[4, 20], [4, 23]])
-        expect(markerAddedHandler).toHaveBeenCalledWith(marker)
+        expect(markerCreatedHandler).toHaveBeenCalledWith(marker)
 
     describe "marker manipulation", ->
       marker = null
@@ -1005,9 +1004,10 @@ describe 'Buffer', ->
         buffer.undo()
         expect(buffer.getMarker(marker2.id)).toBeUndefined()
 
-      it "emits 'marker-removed' when markers are destroyed", ->
+      it "emits 'destroyed' on the marker when it is destroyed", ->
+        marker.on 'destroyed', destroyedHandler = jasmine.createSpy("destroyedHandler")
         marker.destroy()
-        expect(markerRemovedHandler).toHaveBeenCalledWith(marker)
+        expect(destroyedHandler).toHaveBeenCalled()
 
     describe "marker updates due to buffer changes", ->
       [marker1, marker2, marker3] = []
@@ -1185,17 +1185,6 @@ describe 'Buffer', ->
           expect(marker4.isValid()).toBeTruthy()
           expect(marker4.getRange()).toEqual [[4, 20], [4, 23]]
 
-      it "emits 'marker-added' and 'marker-removed' events when markers are invalidated or revalidated", ->
-        marker2.destroy()
-        marker3.destroy()
-        markerRemovedHandler.reset()
-
-        buffer.change([[4, 21], [4, 24]], "foo")
-        expect(markerRemovedHandler).toHaveBeenCalledWith(marker1)
-
-        buffer.undo()
-        expect(markerAddedHandler).toHaveBeenCalledWith(marker1)
-
     describe ".markersForPosition(position)", ->
       it "returns all markers that intersect the given position", ->
         m1 = buffer.markRange([[3, 4], [3, 10]])

src/app/buffer-marker.coffee

@@ -165,6 +165,7 @@ class BufferMarker
   # Destroys the marker
   destroy: ->
     @buffer.destroyMarker(@id)
+    @trigger 'destroyed'
 
   # Returns a {Boolean} indicating whether the marker is valid. Markers can be
   # invalidated when a region surrounding them in the buffer is changed.

src/app/display-buffer-marker.coffee

@@ -15,6 +15,7 @@ class DisplayBufferMarker
 
   constructor: ({@bufferMarker, @displayBuffer}) ->
     @id = @bufferMarker.id
+    @bufferMarker.on 'destroyed', => @destroyed()
 
   ###
   # Public #
@@ -155,6 +156,9 @@ class DisplayBufferMarker
   # Internal #
   ###
 
+  destroyed: ->
+    delete @displayBuffer.markers[@id]
+
   observeBufferMarkerIfNeeded: ->
     return if @subscriptionCount()
     @getHeadScreenPosition() # memoize current value

src/app/display-buffer.coffee

@@ -33,12 +33,7 @@ class DisplayBuffer
     @tokenizedBuffer.on 'grammar-changed', (grammar) => @trigger 'grammar-changed', grammar
     @tokenizedBuffer.on 'changed', @handleTokenizedBufferChange
     @buffer.on 'markers-updated', @handleMarkersUpdated
-    @buffer.on 'marker-added', (marker) =>
-      @trigger 'marker-added', @getMarker(marker.id)
-    @buffer.on 'marker-removed', (marker) =>
-      marker = @getMarker(marker.id)
-      delete @markers[marker.id]
-      @trigger 'marker-removed', marker
+    @buffer.on 'marker-created', (marker) => @trigger 'marker-created', @getMarker(marker.id)
 
   buildLineMap: ->
     @lineMap = new LineMap

src/app/text-buffer.coffee

@@ -476,7 +476,7 @@ class Buffer
       attributes
     }, options))
     @validMarkers[marker.id] = marker
-    @trigger 'marker-added', marker
+    @trigger 'marker-created', marker
     marker
 
   # Public: Constructs a new marker at a given position.
@@ -650,7 +650,6 @@ class Buffer
     if marker = @validMarkers[id] ? @invalidMarkers[id]
       delete @validMarkers[id]
       delete @invalidMarkers[id]
-      @trigger 'marker-removed', marker
 
   scheduleModifiedEvents: ->
     clearTimeout(@stoppedChangingTimeout) if @stoppedChangingTimeout