Move Comparables to vespajlib

2 files changed, 47 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/collections/Comparables.java b/vespajlib/src/main/java/com/yahoo/collections/Comparables.java
new file mode 100644
index 00000000000..e638b1fcd75
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/collections/Comparables.java
@@ -0,0 +1,26 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package com.yahoo.collections;
+
+/**
+ * Utilities for {@link Comparable} classes.
+ *
+ * @author hakon
+ */
+public class Comparables {
+    /**
+     * Returns the least element, or {@code first} if they are equal according to
+     * {@link Comparable#compareTo(Object) compareTo}.
+     */
+    public static <T extends Comparable<? super T>> T min(T first, T second) {
+        return first.compareTo(second) <= 0 ? first : second;
+    }
+
+    /**
+     * Returns the least element, or {@code second} if they are equal according to
+     * {@link Comparable#compareTo(Object) compareTo}.
+     */
+    public static <T extends Comparable<? super T>> T max(T first, T second) {
+        return first.compareTo(second) <= 0 ? second : first;
+    }
+}
diff --git a/vespajlib/src/test/java/com/yahoo/collections/ComparablesTest.java b/vespajlib/src/test/java/com/yahoo/collections/ComparablesTest.java
new file mode 100644
index 00000000000..0ec9cd2d8f7
--- /dev/null
+++ b/vespajlib/src/test/java/com/yahoo/collections/ComparablesTest.java
@@ -0,0 +1,21 @@
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+
+package com.yahoo.collections;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class ComparablesTest {
+    @Test
+    public void testMinAndMax() {
+        Integer i1 = 1;
+        Integer i2 = 2;
+
+        assertEquals(i1, Comparables.min(i1, i2));
+        assertEquals(i1, Comparables.min(i2, i1));
+
+        assertEquals(i2, Comparables.max(i1, i2));
+        assertEquals(i2, Comparables.max(i2, i1));
+    }
+}
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