Give highlight decorations unique id's to avoid potential React errors

Using the marker's id plus the decoration class can cause an error in
the event we apply a decoration with the same class twice to the same
marker. This is admittedly unlikely, but I think it's cleaner to just
allocate unique id's for decoration objects.

spec/editor-component-spec.coffee

@@ -856,6 +856,12 @@ describe "EditorComponent", ->
         regions = node.querySelectorAll('.test-highlight .region')
         expect(regions.length).toBe 2
 
+    it "allows the same marker to be decorated with multiple highlights of the same class", ->
+      editor.addDecorationForMarker(marker, type: 'highlight', class: 'test-highlight')
+      waitsFor -> not component.decorationChangedImmediate?
+      runs ->
+        expect(node.querySelectorAll('.test-highlight').length).toBe 2
+
   describe "hidden input field", ->
     it "renders the hidden input field at the position of the last cursor if the cursor is on screen and the editor is focused", ->
       editor.setVerticalScrollMargin(0)

src/decoration.coffee

@@ -1,5 +1,7 @@
 _ = require 'underscore-plus'
 
+IdCounter = 1
+
 module.exports =
 class Decoration
   @isType: (decoration, decorationType) ->
@@ -9,6 +11,7 @@ class Decoration
       decorationType is decoration.type
 
   constructor: (@marker, properties) ->
+    @id = IdCounter++
     _.extend(this, properties)
 
   getScreenRange: ->
@@ -22,6 +25,7 @@ class Decoration
 
   toObject: ->
     copy = {}
+    copy.id = @id
     copy.valid = @isValid()
     copy.screenRange = @getScreenRange().copy()
 

src/highlights-component.coffee

@@ -17,7 +17,8 @@ HighlightsComponent = React.createClass
     for markerId, decorations of highlightDecorations
       if decorations?
         for decoration in decorations
-          highlightComponents.push(HighlightComponent({key: "#{markerId}-#{decoration.class}", decoration, editor, lineHeightInPixels}))
+          highlightComponents.push(HighlightComponent({key: decoration.id, decoration, editor, lineHeightInPixels}))
+
     highlightComponents
 
   shouldComponentUpdate: (newProps) ->