assertBigArray()

CHANGES

@@ -6,6 +6,9 @@
   methods of hash maps. Thanks to Nikita Sokolov for reporting that some
   methods (e.g., fastForEach()) were not supporting setValue().
 
+- New assertBigArray() methods help to check that arguments are
+  well-formed big arrays.
+
 8.5.11
 
 - Hash-based containers now expose ensureCapacity().

drv/BigArraysFragment.drv

@@ -222,6 +222,22 @@
 #endif
 
 
+	/** Asserts that the provided big array is correct.
+	 *
+	 * @param array a big array.
+	 * @throw IllegalStateException if the last segment is empty or longer than {@link BigArrays#SEGMENT_SIZE},
+	 * or any other segment has length different from {@link BigArrays#SEGMENT_SIZE}.
+	 */
+	public static KEY_GENERIC void assertBigArray(final KEY_GENERIC_TYPE[][] array) {
+		final int l = array.length;
+		if (l == 0) return;
+		for(int i = 0; i < l - 1; i++)
+			if (array[i].length != SEGMENT_SIZE)
+				throw new IllegalStateException("All segments except for the last one must be of length 2^" + Integer.toString(SEGMENT_SHIFT));
+		if (array[l - 1].length > SEGMENT_SIZE) throw new IllegalStateException("The last segment must be of length at most 2^" + Integer.toString(SEGMENT_SHIFT));
+		if (array[l - 1].length == 0 && l == 1) throw new IllegalStateException("The last segment must be of nonzero length");
+	}
+
 	/** Returns the length of the given big array.
 	 *
 	 * @param array a big array.

test/it/unimi/dsi/fastutil/ints/IntBigArraysTest.java

@@ -16,6 +16,7 @@
 
 package it.unimi.dsi.fastutil.ints;
 
+import static it.unimi.dsi.fastutil.BigArrays.SEGMENT_SIZE;
 import static it.unimi.dsi.fastutil.BigArrays.copy;
 import static it.unimi.dsi.fastutil.BigArrays.get;
 import static it.unimi.dsi.fastutil.BigArrays.length;
@@ -525,4 +526,31 @@ public void testBinarySearchLargeKey() {
 	public void testLegacyMainMethodTests() throws Exception {
 		MainRunner.callMainIfExists(IntBigArrays.class, "test", /*num=*/"10000", /*seed=*/"293843");
 	}
-}
+
+	@Test(expected = IllegalStateException.class)
+	public void testAssertBigArrayLastEmpty() {
+		BigArrays.assertBigArray(new int[][] { new int[] {} });
+	}
+
+	@Test(expected = IllegalStateException.class)
+	public void testAssertBigArrayLastLong() {
+		BigArrays.assertBigArray(new int[][] { new int[SEGMENT_SIZE + 1] });
+	}
+
+	@Test(expected = IllegalStateException.class)
+	public void testAssertBigArrayMiddleWrong() {
+		BigArrays.assertBigArray(new int[][] { new int[SEGMENT_SIZE - 1], new int[1] });
+	}
+
+	@Test
+	public void testAssertBigArrayOK() {
+		BigArrays.assertBigArray(IntBigArrays.newBigArray(0));
+		BigArrays.assertBigArray(IntBigArrays.newBigArray(SEGMENT_SIZE));
+		BigArrays.assertBigArray(IntBigArrays.newBigArray(SEGMENT_SIZE - 1));
+		BigArrays.assertBigArray(IntBigArrays.newBigArray(SEGMENT_SIZE + 1));
+		BigArrays.assertBigArray(IntBigArrays.newBigArray(2 * SEGMENT_SIZE));
+		BigArrays.assertBigArray(IntBigArrays.newBigArray(2 * SEGMENT_SIZE - 1));
+		BigArrays.assertBigArray(IntBigArrays.newBigArray(2 * SEGMENT_SIZE + 1));
+	}
+
+}