Version 0.8.10.4

dart/editor/tools/plugins/com.google.dart.tools.ui/src/com/google/dart/tools/ui/internal/text/dart/DartReconcilingRegion.java

 /*
  * Copyright (c) 2013, the Dart project authors.
  * 
  * Licensed under the Eclipse Public License v1.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  * 
  * http://www.eclipse.org/legal/epl-v10.html
  * 
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */
 package com.google.dart.tools.ui.internal.text.dart;
 
-import static java.lang.Math.max;
-import static java.lang.Math.min;
-
 /**
  * Instances of {@code DartReconcilingRegion} represent a source region that has changed.
  */
 public class DartReconcilingRegion {
 
   public static final DartReconcilingRegion EMPTY = new DartReconcilingRegion(0, 0, 0);
 
   private final int offset;
   private final int oldLength;
   private final int newLength;
 
   /**
    * Construct a new instance representing a region of source.
    * 
    * @param offset the offset of the first character that changed
    * @param oldLength the number of characters that were replaced
    * @param newLength the number of characters in the replacement text
    */
   public DartReconcilingRegion(int offset, int oldLength, int newLength) {
     this.offset = offset;
     this.oldLength = oldLength;
     this.newLength = newLength;
   }
 
   /**
-   * Return a new region representing the union of the receiver with the specified region.
+   * Return a new region representing the union of the receiver with the specified region or
+   * {@code null} if the resulting region is disjoint and cannot be represented by this class.
    * 
    * @param offset the offset of the first character that changed
    * @param oldLength the number of characters that were replaced
    * @param newLength the number of characters in the replacement text
+   * @return the region or {@code null} if disjoint
    */
   public DartReconcilingRegion add(int offset, int oldLength, int newLength) {
     if (oldLength == 0 && newLength == 0) {
       return this;
     }
     if (isEmpty()) {
       return new DartReconcilingRegion(offset, oldLength, newLength);
     }
-    int offset2 = min(this.offset, offset);
-    int oldLength2 = max(this.offset + this.oldLength, offset + oldLength) - offset2;
-    int newLength2 = max(this.offset + this.newLength, offset + newLength) - offset2;
+    if (offset + oldLength < this.offset) {
+      return null;
+    }
+    if (offset + oldLength > this.offset + this.newLength) {
+      return null;
+    }
+    int offset2 = Math.min(this.offset, offset);
+    int oldLength2 = this.oldLength + (this.offset - offset2);
+    int newLength2 = this.newLength + (newLength - oldLength) + (this.offset - offset2);
     return new DartReconcilingRegion(offset2, oldLength2, newLength2);
   }
 
   /**
    * Return the number of characters in the replacement text.
    * 
    * @return the offset (greater than or equal to zero)
    */
   public int getNewLength() {
     return newLength;
@@ skipping 19 matching lines @@
 
   /**
    * Return {@code true} if the range represent by the receiver is empty.
    * 
    * @return {@code true} if empty
    */
   public boolean isEmpty() {
     return oldLength == 0 && newLength == 0;
   }
 }