Extract SGR codes interpretation to separate class

app/assets/javascripts/player/brush.js.coffee

@@ -7,9 +7,7 @@ class AsciiIo.Brush
   @hash: (brush) ->
     "#{brush.fg}_#{brush.bg}_#{brush.bright}_#{brush.underline}_#{brush.italic}_#{brush.blink}"
 
-  @create: (options) ->
-    options ||= {}
-
+  @create: (options = {}) ->
     key = @hash(options)
     brush = @cache[key]
 
@@ -19,10 +17,16 @@ class AsciiIo.Brush
 
     brush
 
+  @normal: ->
+    @_normal ||= @create()
+
   constructor: (options) ->
     @fg        = options.fg
     @bg        = options.bg
+    @blink     = options.blink
     @bright    = options.bright
-    @underline = options.underline
     @italic    = options.italic
-    @blink     = options.blink
+    @underline = options.underline
+
+  hash: ->
+    AsciiIo.Brush.hash(this)

app/assets/javascripts/player/sgr_interpreter.js.coffee

@@ -0,0 +1,60 @@
+class AsciiIo.SgrInterpreter
+
+  reset: ->
+    @attrs =
+      fg       : undefined
+      bg       : undefined
+      blink    : false
+      bright   : false
+      italic   : false
+      underline: false
+
+  buildBrush: (oldBrush, numbers) ->
+    @attrs =
+      fg       : oldBrush.fg
+      bg       : oldBrush.bg
+      blink    : oldBrush.blink
+      bright   : oldBrush.bright
+      italic   : oldBrush.italic
+      underline: oldBrush.underline
+
+    numbers = [0] if numbers.length is 0
+
+    i = 0
+    while i < numbers.length
+      n = numbers[i]
+
+      if n is 0
+        @reset()
+      else if n is 1
+        @attrs.bright = true
+      else if n is 3
+        @attrs.italic = true
+      else if n is 4
+        @attrs.underline = true
+      else if n is 5
+        @attrs.blink = true
+      else if n is 23
+        @attrs.italic = false
+      else if n is 24
+        @attrs.underline = false
+      else if n is 25
+        @attrs.blink = false
+      else if n >= 30 and n <= 37
+        @attrs.fg = n - 30
+      else if n is 38
+        @attrs.fg = numbers[i + 2]
+        i += 2
+      else if n is 39
+        @attrs.fg = undefined
+      else if n >= 40 and n <= 47
+        @attrs.bg = n - 40
+      else if n is 48
+        @attrs.bg = numbers[i + 2]
+        i += 2
+      else if n is 49
+        @attrs.bg = undefined
+
+      i++
+
+    AsciiIo.Brush.create @attrs

app/assets/javascripts/player/terminal_view.js.coffee

@@ -71,13 +71,13 @@ class AsciiIo.TerminalView extends Backbone.View
     @$el.find(".line:eq(" + n + ")").html html
 
   spanFromBrush: (brush, hasCursor) ->
-    key = "#{AsciiIo.Brush.hash(brush)}_#{hasCursor}"
+    key = "#{brush.hash()}_#{hasCursor}"
     span = @cachedSpans[key]
 
     if not span
       span = ""
 
-      if hasCursor or brush.fg isnt undefined or brush.bg isnt undefined or brush.bright or brush.underline
+      if hasCursor or brush != AsciiIo.Brush.normal()
         span = "<span class=\""
 
         if brush.fg isnt undefined

app/assets/javascripts/player/vt.js.coffee

@@ -1,6 +1,7 @@
 class AsciiIo.VT
 
   constructor: (@cols, @lines, @view) ->
+    @sgrInterpreter = new AsciiIo.SgrInterpreter()
     @data = ''
     @resetTerminal()
     @render()
@@ -256,57 +257,7 @@ class AsciiIo.VT
         throw "no handler for CSI term: " + term
 
   handleSGR: (numbers) ->
-    numbers = [0] if numbers.length is 0
-
-    i = 0
-    while i < numbers.length
-      n = numbers[i]
-
-      if n is 0
-        @fg = @bg = undefined
-        @bright = false
-        @underline = false
-        # TODO: reset blink (and others?)
-      else if n is 1
-        @bright = true
-      else if n is 3
-        @italic = true
-      else if n is 4
-        @underline = true
-      else if n is 5
-        @blink = true
-      else if n is 23
-        @italic = false
-      else if n is 24
-        @underline = false
-      else if n is 25
-        @blink = false
-      else if n >= 30 and n <= 37
-        @fg = n - 30
-      else if n is 38
-        @fg = numbers[i + 2]
-        i += 2
-      else if n is 39
-        @fg = undefined
-      else if n >= 40 and n <= 47
-        @bg = n - 40
-      else if n is 48
-        @bg = numbers[i + 2]
-        i += 2
-      else if n is 49
-        @bg = undefined
-
-      i++
-
-    props = {}
-    props.fg = @fg if @fg isnt undefined
-    props.bg = @bg if @bg isnt undefined
-    props.bright = true if @bright
-    props.underline = true if @underline
-    props.italic = true if @italic
-    props.blink = true if @blink
-
-    @buffer.setBrush AsciiIo.Brush.create(props)
+    @buffer.setBrush @sgrInterpreter.buildBrush(@buffer.brush, numbers)
 
   bell: ->
     @view.visualBell()

spec/javascripts/player/sgr_interpreter_spec.js.coffee

@@ -0,0 +1,6 @@
+describe 'AsciiIo.SgrInterpreter', ->
+
+  describe '#reset', ->
+
+  describe '#buildBrush', ->
+