WIP: Wrap lines at token boundaries when soft wrap is on

This is still really rough... cursor positioning isn't working properly
yet. Nor does anything adjust when the window is resized.

spec/atom/editor-spec.coffee

@@ -50,6 +50,16 @@ describe "Editor", ->
         buffer.insert([1,0], "/*")
         expect(editor.lines.find('.line:eq(2) span:eq(0)')).toMatchSelector '.comment'
 
+    describe "when soft-wrap is enabled", ->
+      beforeEach ->
+        editor.attachToDom()
+        editor.width(editor.charWidth * 50)
+        editor.setSoftWrap(true)
+
+      it "wraps lines that are too long to fit within the editor's width", ->
+        expect(editor.lines.find('pre:eq(3)').text()).toBe "    var pivot = items.shift(), current, left = [],"
+        expect(editor.lines.find('pre:eq(4)').text()).toBe " right = [];"
+
   describe "cursor movement", ->
     describe ".setCursorPosition({row, column})", ->
       beforeEach ->

src/atom/editor.coffee

@@ -19,6 +19,7 @@ class Editor extends View
 
   vScrollMargin: 2
   hScrollMargin: 10
+  softWrap: false
   cursor: null
   buffer: null
   undoManager: null
@@ -112,24 +113,43 @@ class Editor extends View
 
 
   buildLineElement: (row) ->
-    tokens = @highlighter.tokensForRow(row)
+    maxSegmentLength =
+      if @softWrap
+        Math.floor(@width() / @charWidth)
+      else
+        Infinity
+    currentSegmentLength = 0
+    currentSegment = []
+    segments = [currentSegment]
+
+    for token in @highlighter.tokensForRow(row)
+      if (currentSegmentLength + token.value.length) <= maxSegmentLength
+        currentSegmentLength += token.value.length
+        currentSegment.push(token)
+      else
+        currentSegment = [token]
+        currentSegmentLength = token.value.length
+        segments.push(currentSegment)
+
     $$ ->
-      @pre class: 'line', =>
-        if tokens.length
-          for token in tokens
-            @span { class: token.type.replace('.', ' ') }, token.value
-        else
-          @raw '&nbsp;'
-
-  setBuffer: (@buffer) ->
-    @highlighter = new Highlighter(@buffer)
-    @undoManager = new UndoManager(@buffer)
+      for segment in segments
+        @pre class: 'line', =>
+          if segment.length
+            for token in segment
+              @span { class: token.type.replace('.', ' ') }, token.value
+          else
+            @raw '&nbsp;'
 
+  renderLines: ->
     @lines.empty()
     for row in [0..@buffer.lastRow()]
       line = @buildLineElement(row)
       @lines.append line
 
+  setBuffer: (@buffer) ->
+    @highlighter = new Highlighter(@buffer)
+    @undoManager = new UndoManager(@buffer)
+    @renderLines()
     @setCursorPosition(row: 0, column: 0)
 
     @buffer.on 'change', (e) =>
@@ -165,6 +185,9 @@ class Editor extends View
   getLineElement: (row) ->
     @lines.find("pre.line:eq(#{row})")
 
+  setSoftWrap: (@softWrap) ->
+    @renderLines()
+
   clipPosition: ({row, column}) ->
     if row > @buffer.lastRow()
       row = @buffer.lastRow()