Merge branch 'documentation/JAL-3407_2.11.1_release' into releases/Release_2_11_1_Branch

[jalview.git] / src / jalview / ext / android / SparseIntArray.java

diff --git a/src/jalview/ext/android/SparseIntArray.java b/src/jalview/ext/android/SparseIntArray.java
index 4ddf776..fcd4f1f 100644 (file)
--- a/src/jalview/ext/android/SparseIntArray.java
+++ b/src/jalview/ext/android/SparseIntArray.java
@@ -40,6 +40,13 @@ package jalview.ext.android;
  * order in the case of <code>valueAt(int)<code>.
  * </p>
  */
+
+/*
+ * Imported into Jalview September 2016
+ * Change log:
+ *   Sep 2016 method add(int, int) added for more efficient increment of counts
+ *            (a single binary search, rather than one on read and one on write)
+ */
 public class SparseIntArray implements Cloneable
 {
   private int[] mKeys;
@@ -354,13 +361,19 @@ public class SparseIntArray implements Cloneable
    * 
    * @param key
    * @oparam toAdd
+   * @return the new value of the count for the key
+   * @throw ArithmeticException if the result would exceed the maximum value of
+   *        an int
    */
-  public void add(int key, int toAdd)
+  public int add(int key, int toAdd)
   {
+    int newValue = toAdd;
     int i = ContainerHelpers.binarySearch(mKeys, mSize, key);
     if (i >= 0)
     {
+      checkOverflow(mValues[i], toAdd);
       mValues[i] += toAdd;
+      newValue = mValues[i];
     }
     else
     {
@@ -370,7 +383,6 @@ public class SparseIntArray implements Cloneable
         int n = idealIntArraySize(mSize + 1);
         int[] nkeys = new int[n];
         int[] nvalues = new int[n];
-        // Log.e("SparseIntArray", "grow " + mKeys.length + " to " + n);
         System.arraycopy(mKeys, 0, nkeys, 0, mKeys.length);
         System.arraycopy(mValues, 0, nvalues, 0, mValues.length);
         mKeys = nkeys;
@@ -378,7 +390,6 @@ public class SparseIntArray implements Cloneable
       }
       if (mSize - i != 0)
       {
-        // Log.e("SparseIntArray", "move " + (mSize - i));
         System.arraycopy(mKeys, i, mKeys, i + 1, mSize - i);
         System.arraycopy(mValues, i, mValues, i + 1, mSize - i);
       }
@@ -386,5 +397,36 @@ public class SparseIntArray implements Cloneable
       mValues[i] = toAdd;
       mSize++;
     }
+    return newValue;
+  }
+
+  /**
+   * Throws ArithmeticException if adding addend to value would exceed the range
+   * of int
+   * 
+   * @param value
+   * @param addend
+   */
+  static void checkOverflow(int value, int addend)
+  {
+    /*
+     * test cases being careful to avoid overflow while testing!
+     */
+    if (addend > 0)
+    {
+      if (value > 0 && Integer.MAX_VALUE - value < addend)
+      {
+        throw new ArithmeticException("Integer overflow adding " + addend
+                + " to  " + value);
+      }
+    }
+    else if (addend < 0)
+    {
+      if (value < 0 && Integer.MIN_VALUE - value > addend)
+      {
+        throw new ArithmeticException("Integer underflow adding " + addend
+                + " to  " + value);
+      }
+    }
   }
 }