WIP: Add a LineWrapper object

Only passing specs are focused. Everything is still broken. Editor uses
the line wrapper to render lines, but the line wrapper isn't updating
on buffer change events yet. Still moving vertically and clipping
positions based on unwrapped lines as well.

spec/atom/editor-spec.coffee

@@ -50,15 +50,21 @@ describe "Editor", ->
         buffer.insert([1,0], "/*")
         expect(editor.lines.find('.line:eq(2) span:eq(0)')).toMatchSelector '.comment'
 
-    describe "when soft-wrap is enabled", ->
+    fdescribe "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 = [];"
+      it "wraps lines that are too long to fit within the editor's width, adjusting cursor positioning accordingly", ->
+        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 = [];"
+
+        editor.cursor.setPosition([3, 52])
+        expect(editor.cursor.position()).toEqual(editor.lines.find('pre:eq(4)').position())
+
+        editor.cursor.setPosition([4, 0])
+        expect(editor.cursor.position()).toEqual(editor.lines.find('pre:eq(5)').position())
 
   describe "cursor movement", ->
     describe ".setCursorPosition({row, column})", ->

spec/atom/line-wrapper-spec.coffee

@@ -0,0 +1,51 @@
+Buffer = require 'buffer'
+LineWrapper = require 'line-wrapper'
+Highlighter = require 'highlighter'
+_ = require 'underscore'
+
+fdescribe "LineWrapper", ->
+  [wrapper, buffer] = []
+
+  beforeEach ->
+    buffer = new Buffer(require.resolve('fixtures/sample.js'))
+    wrapper = new LineWrapper(50, new Highlighter(buffer))
+
+  describe ".segmentsForRow(row)", ->
+    describe "when the line does not need to wrap", ->
+      it "returns tokens for a single segment", ->
+        line = buffer.getLine(0)
+        expect(line.length).toBeLessThan(50)
+        segments = wrapper.segmentsForRow(0)
+        expect(segments.length).toBe 1
+        expect(segments[0].lastIndex).toBe line.length
+
+    describe "when the line needs to wrap once", ->
+      it "breaks the line into 2 segments at the beginning of the first word that exceeds the max length", ->
+        line = buffer.getLine(6)
+        expect(line.length).toBeGreaterThan 50
+        segments = wrapper.segmentsForRow(6)
+        expect(segments.length).toBe 2
+        expect(segments[0].lastIndex).toBe 45
+        expect(segments[0].map((t) -> t.value).join('')).toBe '      current < pivot ? left.push(current) : '
+
+        expect(segments[1].lastIndex).toBe 65
+        expect(segments[1].map((t) -> t.value).join('')).toBe 'right.push(current);'
+
+    describe "when the line needs to wrap more than once", ->
+      it "breaks the line into multiple segments", ->
+        wrapper.setMaxLength(30)
+        segments = wrapper.segmentsForRow(6)
+
+        expect(segments.length).toBe 3
+
+        expect(segments[0].lastIndex).toBe 24
+        expect(_.pluck(segments[0], 'value').join('')).toBe '      current < pivot ? '
+
+        expect(segments[1].lastIndex).toBe 45
+        expect(_.pluck(segments[1], 'value').join('')).toBe 'left.push(current) : '
+
+        expect(segments[2].lastIndex).toBe 65
+        expect(_.pluck(segments[2], 'value').join('')).toBe 'right.push(current);'
+
+  describe "when the buffer changes", ->
+    

src/atom/editor.coffee

@@ -4,6 +4,7 @@ Point = require 'point'
 Cursor = require 'cursor'
 Selection = require 'selection'
 Highlighter = require 'highlighter'
+LineWrapper = require 'line-wrapper'
 UndoManager = require 'undo-manager'
 Range = require 'range'
 
@@ -20,12 +21,14 @@ class Editor extends View
   vScrollMargin: 2
   hScrollMargin: 10
   softWrap: false
-  cursor: null
-  buffer: null
-  undoManager: null
-  selection: null
   lineHeight: null
   charWidth: null
+  cursor: null
+  selection: null
+  buffer: null
+  highlighter: null
+  lineWrapper: null
+  undoManager: null
 
   initialize: () ->
     requireStylesheet 'editor.css'
@@ -111,26 +114,8 @@ class Editor extends View
     @on 'mousemove', moveHandler
     $(document).one 'mouseup', => @off 'mousemove', moveHandler
 
-
   buildLineElement: (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)
-
+    segments = @lineWrapper.segmentsForRow(row)
     $$ ->
       for segment in segments
         @pre class: 'line', =>
@@ -148,6 +133,7 @@ class Editor extends View
 
   setBuffer: (@buffer) ->
     @highlighter = new Highlighter(@buffer)
+    @lineWrapper = new LineWrapper(Infinity, @highlighter)
     @undoManager = new UndoManager(@buffer)
     @renderLines()
     @setCursorPosition(row: 0, column: 0)
@@ -186,6 +172,13 @@ class Editor extends View
     @lines.find("pre.line:eq(#{row})")
 
   setSoftWrap: (@softWrap) ->
+    maxLength =
+      if @softWrap
+        Math.floor(@width() / @charWidth)
+      else
+        infinity
+
+    @lineWrapper.setMaxLength(maxLength)
     @renderLines()
 
   clipPosition: ({row, column}) ->
@@ -199,7 +192,17 @@ class Editor extends View
     new Point(row, column)
 
   pixelPositionFromPoint: ({row, column}) ->
-    { top: row * @lineHeight, left: column * @charWidth }
+    segmentsAbove = 0
+    segmentsAbove += @lineWrapper.segmentsForRow(i).length for i in [0...row]
+
+    for segment in @lineWrapper.segmentsForRow(row)
+      if column > segment.lastIndex
+        segmentsAbove++
+        column -= segment.textLength
+      else
+        break
+
+    { top: segmentsAbove * @lineHeight, left: column * @charWidth }
 
   pointFromPixelPosition: ({top, left}) ->
     { row: Math.floor(top / @lineHeight), column: Math.floor(left / @charWidth) }

src/atom/line-wrapper.coffee

@@ -0,0 +1,52 @@
+getWordRegex = -> /\b[^\s]+/g
+
+module.exports =
+class LineWrapper
+  constructor: (@maxLength, @highlighter) ->
+    @buffer = @highlighter.buffer
+    @segmentBuffer()
+
+  setMaxLength: (@maxLength) ->
+    @segmentBuffer()
+
+  segmentBuffer: ->
+    @lines = @segmentRows(0, @buffer.lastRow())
+
+  segmentsForRow: (row) ->
+    @lines[row]
+
+  segmentRows: (start, end) ->
+    for row in [start..end]
+      @segmentRow(row)
+
+  segmentRow: (row) ->
+    wordRegex = getWordRegex()
+    line = @buffer.getLine(row)
+
+    breakIndices = []
+    lastBreakIndex = 0
+
+    while match = wordRegex.exec(line)
+      startIndex = match.index
+      endIndex = startIndex + match[0].length
+      if endIndex - lastBreakIndex > @maxLength
+        breakIndices.push(startIndex)
+        lastBreakIndex = startIndex
+
+    currentSegment = []
+    currentSegment.lastIndex = 0
+    segments = [currentSegment]
+    nextBreak = breakIndices.shift()
+    for token in @highlighter.tokensForRow(row)
+      if currentSegment.lastIndex >= nextBreak
+        nextBreak = breakIndices.shift()
+        newSegment = []
+        newSegment.lastIndex = currentSegment.lastIndex
+        newSegment.textLength = 0
+        segments.push(newSegment)
+        currentSegment = newSegment
+      currentSegment.push token
+      currentSegment.lastIndex += token.value.length
+      currentSegment.textLength += token.value.length
+
+    segments