Compare against EOF position when clipping

Previously the column could potentially be set to
zero since a Math.min comparison was used for the
length of an already adjusted row.

spec/app/buffer-spec.coffee

@@ -889,3 +889,17 @@ describe 'Buffer', ->
             buffer.setText("\ninitialtext")
             buffer.append("hello\n1\r\n2\n")
             expect(buffer.getText()).toBe "\ninitialtexthello\n1\n2\n"
+
+  describe ".clipPosition(position)", ->
+    describe "when the position is before the start of the buffer", ->
+      it "returns the first position in the buffer", ->
+        expect(buffer.clipPosition([-1,0])).toEqual [0,0]
+        expect(buffer.clipPosition([0,-1])).toEqual [0,0]
+        expect(buffer.clipPosition([-1,-1])).toEqual [0,0]
+
+    describe "when the position is after the end of the buffer", ->
+      it "returns the last position in the buffer", ->
+        buffer.setText('some text')
+        expect(buffer.clipPosition([1, 0])).toEqual [0,9]
+        expect(buffer.clipPosition([0,10])).toEqual [0,9]
+        expect(buffer.clipPosition([10,Infinity])).toEqual [0,9]

src/app/buffer.coffee

@@ -212,13 +212,15 @@ class Buffer
     range
 
   clipPosition: (position) ->
-    { row, column } = Point.fromObject(position)
-    row = 0 if row < 0
-    column = 0 if column < 0
-    row = Math.min(@getLastRow(), row)
-    column = Math.min(@lineLengthForRow(row), column)
-
-    new Point(row, column)
+    position = Point.fromObject(position)
+    eofPosition = @getEofPosition()
+    if position.isGreaterThan(eofPosition)
+      eofPosition
+    else
+      row = Math.max(position.row, 0)
+      column = Math.max(position.column, 0)
+      column = Math.min(@lineLengthForRow(row), column)
+      new Point(row, column)
 
   clipRange: (range) ->
     range = Range.fromObject(range)