Remove ability to associate a binding set with a function

This was cool, but it's really hard to optimize the keymap with this feature because we never know if a keystroke will match against a binding set with a function, which will force us to always consider this binding set against every key event.

spec/app/keymap-spec.coffee

@@ -216,8 +216,7 @@ describe "Keymap", ->
       describe "when there is a complete binding with a more specific selector", ->
         it "favors the more specific complete match", ->
 
-  describe ".bindKeys(selector, fnOrMap)", ->
+  describe ".bindKeys(selector, hash)", ->
-    describe "when called with a selector and a hash", ->
     it "normalizes the key patterns in the hash to put the modifiers in alphabetical order", ->
       fooHandler = jasmine.createSpy('fooHandler')
       fragment.on 'foo', fooHandler
@@ -232,56 +231,6 @@ describe "Keymap", ->
       expect(result).toBe(false)
       expect(fooHandler).toHaveBeenCalled()
 
-    describe "when called with a selector and a function", ->
-      it "calls the given function when selector matches", ->
-        handler = jasmine.createSpy 'handler'
-        keymap.bindKeys '.child-node', handler
-
-        target = fragment.find('.grandchild-node')[0]
-        event = keydownEvent('y', target: target)
-        keymap.handleKeyEvent event
-
-        expect(handler).toHaveBeenCalledWith(event)
-
-      describe "when the function returns a command string", ->
-        it "triggers the command event on the target and stops propagating the event", ->
-          keymap.bindKeys '*', 'x': 'foo'
-          keymap.bindKeys '*', -> 'bar'
-          fooHandler = jasmine.createSpy('fooHandler')
-          barHandler = jasmine.createSpy('barHandler')
-          fragment.on 'foo', fooHandler
-          fragment.on 'bar', barHandler
-
-          target = fragment.find('.child-node')[0]
-          keymap.handleKeyEvent(keydownEvent('x', target: target))
-
-          expect(fooHandler).not.toHaveBeenCalled()
-          expect(barHandler).toHaveBeenCalled()
-
-      describe "when the function returns false", ->
-        it "stops propagating the event", ->
-          keymap.bindKeys '*', 'x': 'foo'
-          keymap.bindKeys '*', -> false
-          fooHandler = jasmine.createSpy('fooHandler')
-          fragment.on 'foo', fooHandler
-
-          target = fragment.find('.child-node')[0]
-          keymap.handleKeyEvent(keydownEvent('x', target: target))
-
-          expect(fooHandler).not.toHaveBeenCalled()
-
-      describe "when the function returns anything other than a string or false", ->
-        it "continues to propagate the event", ->
-          keymap.bindKeys '*', 'x': 'foo'
-          keymap.bindKeys '*', -> undefined
-          fooHandler = jasmine.createSpy('fooHandler')
-          fragment.on 'foo', fooHandler
-
-          target = fragment.find('.child-node')[0]
-          keymap.handleKeyEvent(keydownEvent('x', target: target))
-
-          expect(fooHandler).toHaveBeenCalled()
-
   describe ".keystrokeStringForEvent(event)", ->
     describe "when no modifiers are pressed", ->
       it "returns a string that identifies the key pressed", ->

src/app/binding-set.coffee

@@ -12,16 +12,12 @@ class BindingSet
   commandForEvent: null
   parser: null
 
-  constructor: (@selector, mapOrFunction, @index) ->
+  constructor: (@selector, commandsByKeystrokes, @index) ->
     @parser = PEG.buildParser(fs.read(require.resolve 'keystroke-pattern.pegjs'))
     @specificity = Specificity(@selector)
-    @commandsByKeystrokes = {}
+    @commandsByKeystrokes = @normalizeCommandsByKeystrokes(commandsByKeystrokes)
 
-    if _.isFunction(mapOrFunction)
+  commandForEvent: (event) ->
-      @commandForEvent = mapOrFunction
-    else
-      @commandsByKeystrokes = @normalizeCommandsByKeystrokes(mapOrFunction)
-      @commandForEvent = (event) =>
     for keystrokes, command of @commandsByKeystrokes
       return command if event.keystrokes == keystrokes
     null