1 files changed, 87 insertions, 0 deletions
diff --git a/predicate-search/src/main/java/com/yahoo/search/predicate/index/Interval.java b/predicate-search/src/main/java/com/yahoo/search/predicate/index/Interval.java
new file mode 100644
index 00000000000..f63a13f3641
--- /dev/null
+++ b/predicate-search/src/main/java/com/yahoo/search/predicate/index/Interval.java
@@ -0,0 +1,87 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.predicate.index;
+
+/**
+ * Utility class for interval related constants and methods.
+ * An interval consists of a begin and end value indicating the start and end of the interval.
+ * Both value are inclusive, eg (1,2) is an interval of size 2.
+ *
+ * There are 3 types of interval; normal, ZStar1 and ZStar2.
+ *
+ * Normal intervals have begin value in 16 MSB and end in 16 LSB.
+ * ZStar1 intervals have end value in 16 MSB and begin in 16 LSB.
+ * ZStar2 intervals have only an end value located at 16 LSB.
+ *
+ * @author <a href="mailto:magnarn@yahoo-inc.com">Magnar Nedland</a>
+ * @author bjorncs
+ */
+public class Interval {
+
+    public static final int INTERVAL_BEGIN = 0x01;
+    public static final int MAX_INTERVAL_END = 0xffff;
+    public static final int ZERO_CONSTRAINT_RANGE = 1;
+
+    private Interval() {}
+
+    public static int fromBoundaries(int begin, int end) {
+        assert begin >= INTERVAL_BEGIN && begin <= MAX_INTERVAL_END
+                && end >= INTERVAL_BEGIN && end <= MAX_INTERVAL_END : toString(begin, end);
+        return (begin << 16) | end;
+    }
+
+    public static int fromZStar1Boundaries(int begin, int end) {
+        assert begin >= 0 && begin <= MAX_INTERVAL_END
+                && end >= INTERVAL_BEGIN && end <= MAX_INTERVAL_END : toString(end, begin);
+        return (end << 16) | begin;
+    }
+
+    public static int fromZStar2Boundaries(int end) {
+        assert end >= INTERVAL_BEGIN && end <= MAX_INTERVAL_END : toString(0, end);
+        return end;
+    }
+
+    public static boolean isZStar1Interval(int interval) {
+        return getBegin(interval) > getEnd(interval);
+    }
+
+    public static boolean isZStar2Interval(int interval) {
+        return (interval & 0xffff0000) == 0;
+    }
+
+    public static int getBegin(int interval) {
+        return interval >>> 16;
+    }
+
+    public static int getEnd(int interval) {
+        return interval & 0xffff;
+    }
+
+    public static int getZStar1Begin(int interval) {
+        return getEnd(interval);
+    }
+
+    public static int getZStar1End(int interval) {
+        return getBegin(interval);
+    }
+
+    public static int getZStar2End(int interval) {
+        return interval;
+    }
+
+    /**
+     * @return A new ZStar1 interval with boundaries [end(zStar1)+1, end(zStar2)]
+     */
+    public static int combineZStarIntervals(int zStar1, int zStar2) {
+        return zStar1 >>> 16 | zStar2 << 16;
+    }
+
+    private static String toString(int begin, int end) {
+        if (begin == 0) {
+            return String.format("[%d]**", end);
+        } else if (begin > end) {
+            return String.format("[%d, %d]*", begin, end);
+        }
+        return String.format("[%d, %d]", begin, end);
+    }
+
+}