Create methods for getting and setting preferred line endings

spec/text-buffer-spec.coffee

@@ -2245,6 +2245,30 @@ describe "TextBuffer", ->
             buffer.append("hello\n1\r\n2\n")
             expect(buffer.getText()).toBe "\ninitialtexthello\n1\n2\n"
 
+    describe "::setPreferredLineEnding(lineEnding)", ->
+      it "uses the given line ending when normalizing, rather than inferring one from the surrounding text", ->
+        buffer = new TextBuffer(text: "a \r\n")
+
+        expect(buffer.getPreferredLineEnding()).toBe null
+        buffer.append(" b \n")
+        expect(buffer.getText()).toBe "a \r\n b \r\n"
+
+        buffer.setPreferredLineEnding("\n")
+        expect(buffer.getPreferredLineEnding()).toBe "\n"
+        buffer.append(" c \n")
+        expect(buffer.getText()).toBe "a \r\n b \r\n c \n"
+
+        buffer.setPreferredLineEnding(null)
+        buffer.append(" d \r\n")
+        expect(buffer.getText()).toBe "a \r\n b \r\n c \n d \n"
+
+      it "persists across serialization and deserialization", ->
+        bufferA = new TextBuffer
+        bufferA.setPreferredLineEnding("\r\n")
+
+        bufferB = TextBuffer.deserialize(bufferA.serialize())
+        expect(bufferB.getPreferredLineEnding()).toBe "\r\n"
+
   describe "character set encoding support", ->
     it "allows the encoding to be set on creation", ->
       filePath = join(__dirname, 'fixtures', 'win1251.txt')

src/text-buffer.coffee

@@ -99,6 +99,7 @@ class TextBuffer
     @history = params?.history ? new History(this)
     @markerStore = params?.markerStore ? new MarkerStore(this)
     @setEncoding(params?.encoding)
+    @setPreferredLineEnding(params?.preferredLineEnding)
 
     @loaded = false
     @transactCallDepth = 0
@@ -125,6 +126,7 @@ class TextBuffer
     filePath: @getPath()
     modifiedWhenLastPersisted: @isModified()
     digestWhenLastPersisted: @file?.getDigestSync()
+    preferredLineEnding: @preferredLineEnding
 
   ###
   Section: Event Subscription
@@ -392,6 +394,12 @@ class TextBuffer
   # Public: Returns the {String} encoding of this buffer.
   getEncoding: -> @encoding ? @file?.getEncoding()
 
+  setPreferredLineEnding: (preferredLineEnding=null) ->
+    @preferredLineEnding = preferredLineEnding
+
+  getPreferredLineEnding: ->
+    @preferredLineEnding
+
   # Public: Get the path of the associated file.
   #
   # Returns a {String}.
@@ -652,8 +660,8 @@ class TextBuffer
 
     # Determine how to normalize the line endings of inserted text if enabled
     if normalizeLineEndings
-      normalizedEnding = @lineEndingForRow(startRow)
-      if normalizedEnding is ''
+      normalizedEnding = @preferredLineEnding ? @lineEndingForRow(startRow)
+      unless normalizedEnding
         if startRow > 0
           normalizedEnding = @lineEndingForRow(startRow - 1)
         else