[merge addon] Add leftChunks and rightChunks methods

Issue #2334

addon/merge/merge.js

@@ -353,6 +353,12 @@
     setShowDifferences: function(val) {
       if (this.right) this.right.setShowDifferences(val);
       if (this.left) this.left.setShowDifferences(val);
+    },
+    rightChunks: function() {
+      return this.right && getChunks(this.right.diff);
+    },
+    leftChunks: function() {
+      return this.left && getChunks(this.left.diff);
     }
   };
 
@@ -403,6 +409,15 @@
       f(startOrig, orig.line + 1, startEdit, edit.line + 1);
   }
 
+  function getChunks(diff) {
+    var collect = [];
+    iterateChunks(diff, function(topOrig, botOrig, topEdit, botEdit) {
+      collect.push({origFrom: topOrig, origTo: botOrig,
+                    editFrom: topEdit, editTo: botEdit});
+    });
+    return collect;
+  }
+
   function endOfLineClean(diff, i) {
     if (i == diff.length - 1) return true;
     var next = diff[i + 1][1];