Merge branch 'master' into bjormel/aws-main-controllerbjormel/aws-main-controller

1 files changed, 54 insertions, 0 deletions

diff --git a/vespajlib/src/main/java/com/yahoo/collections/Optionals.java b/vespajlib/src/main/java/com/yahoo/collections/Optionals.java
new file mode 100644
index 00000000000..27a1e837900
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/collections/Optionals.java
@@ -0,0 +1,54 @@
+package com.yahoo.collections;
+
+import com.google.common.collect.Comparators;
+
+import java.util.Optional;
+import java.util.function.BinaryOperator;
+
+/**
+ * @author jonmv
+ */
+public class Optionals {
+
+    private Optionals() { }
+
+    /** Returns the first non-empty optional, or empty if all are empty. */
+    @SafeVarargs
+    public static <T> Optional<T> firstNonEmpty(Optional<T>... optionals) {
+        for (Optional<T> optional : optionals)
+            if (optional.isPresent())
+                return optional;
+        return Optional.empty();
+    }
+
+    /** Returns the non-empty optional with the lowest value, or empty if all are empty. */
+    @SafeVarargs
+    public static <T extends Comparable<T>> Optional<T> min(Optional<T>... optionals) {
+        Optional<T> best = Optional.empty();
+        for (Optional<T> optional : optionals)
+            if (best.isEmpty() || optional.isPresent() && optional.get().compareTo(best.get()) < 0)
+                best = optional;
+        return best;
+    }
+
+    /** Returns the non-empty optional with the highest value, or empty if all are empty. */
+    @SafeVarargs
+    public static <T extends Comparable<T>> Optional<T> max(Optional<T>... optionals) {
+        Optional<T> best = Optional.empty();
+        for (Optional<T> optional : optionals)
+            if (best.isEmpty() || optional.isPresent() && optional.get().compareTo(best.get()) > 0)
+                best = optional;
+        return best;
+    }
+
+    /** Returns whether either optional is empty, or both are present and equal. */
+    public static <T> boolean equalIfBothPresent(Optional<T> first, Optional<T> second) {
+        return first.isEmpty() || second.isEmpty() || first.equals(second);
+    }
+
+    /** Returns whether the optional is empty, or present and equal to the given value. */
+    public static <T> boolean emptyOrEqual(Optional<T> optional, T value) {
+        return optional.isEmpty() || optional.equals(Optional.of(value));
+    }
+
+}