--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/share/classes/java/util/OptionalInt.java Tue Mar 19 16:05:34 2013 -0700
@@ -0,0 +1,245 @@
+/*
+ * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation. Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package java.util;
+
+import java.util.function.IntConsumer;
+import java.util.function.IntSupplier;
+import java.util.function.Supplier;
+
+/**
+ * A container object which may or may not contain a {@code int} value.
+ * If a value is present, {@code isPresent()} will return {@code true} and
+ * {@code get()} will return the value.
+ *
+ * <p>Additional methods that depend on the presence or absence of a contained
+ * value are provided, such as {@link #orElse(int) orElse()}
+ * (return a default value if value not present) and
+ * {@link #ifPresent(java.util.function.IntConsumer) ifPresent()} (execute a block
+ * of code if the value is present).
+ *
+ * @since 1.8
+ */
+public final class OptionalInt {
+ /**
+ * Common instance for {@code empty()}.
+ */
+ private static final OptionalInt EMPTY = new OptionalInt();
+
+ /**
+ * If true then the value is present, otherwise indicates no value is present
+ */
+ private final boolean isPresent;
+ private final int value;
+
+ /**
+ * Construct an empty instance.
+ *
+ * @implNote Generally only one empty instance, {@link OptionalInt#EMPTY},
+ * should exist per VM.
+ */
+ private OptionalInt() {
+ this.isPresent = false;
+ this.value = 0;
+ }
+
+ /**
+ * Returns an empty {@code OptionalInt} instance. No value is present for this
+ * OptionalInt.
+ *
+ * @apiNote Though it may be tempting to do so, avoid testing if an object
+ * is empty by comparing with {@code ==} against instances returned by
+ * {@code Option.empty()}. There is no guarantee that it is a singleton.
+ * Instead, use {@link #isPresent()}.
+ *
+ * @return an empty {@code OptionalInt}
+ */
+ public static OptionalInt empty() {
+ return EMPTY;
+ }
+
+ /**
+ * Construct an instance with the value present.
+ *
+ * @param value the int value to be present
+ */
+ private OptionalInt(int value) {
+ this.isPresent = true;
+ this.value = value;
+ }
+
+ /**
+ * Return an {@code OptionalInt} with the specified value present.
+ *
+ * @param value the value to be present
+ * @return an {@code OptionalInt} with the value present
+ */
+ public static OptionalInt of(int value) {
+ return new OptionalInt(value);
+ }
+
+ /**
+ * If a value is present in this {@code OptionalInt}, returns the value,
+ * otherwise throws {@code NoSuchElementException}.
+ *
+ * @return the value held by this {@code OptionalInt}
+ * @throws NoSuchElementException if there is no value present
+ *
+ * @see OptionalInt#isPresent()
+ */
+ public int getAsInt() {
+ if (!isPresent) {
+ throw new NoSuchElementException("No value present");
+ }
+ return value;
+ }
+
+ /**
+ * Return {@code true} if there is a value present, otherwise {@code false}.
+ *
+ * @return {@code true} if there is a value present, otherwise {@code false}
+ */
+ public boolean isPresent() {
+ return isPresent;
+ }
+
+ /**
+ * Have the specified consumer accept the value if a value is present,
+ * otherwise do nothing.
+ *
+ * @param consumer block to be executed if a value is present
+ * @throws NullPointerException if value is present and {@code consumer} is
+ * null
+ */
+ public void ifPresent(IntConsumer consumer) {
+ if (isPresent)
+ consumer.accept(value);
+ }
+
+ /**
+ * Return the value if present, otherwise return {@code other}.
+ *
+ * @param other the value to be returned if there is no value present
+ * @return the value, if present, otherwise {@code other}
+ */
+ public int orElse(int other) {
+ return isPresent ? value : other;
+ }
+
+ /**
+ * Return the value if present, otherwise invoke {@code other} and return
+ * the result of that invocation.
+ *
+ * @param other a {@code IntSupplier} whose result is returned if no value
+ * is present
+ * @return the value if present otherwise the result of {@code other.getAsInt()}
+ * @throws NullPointerException if value is not present and {@code other} is
+ * null
+ */
+ public int orElseGet(IntSupplier other) {
+ return isPresent ? value : other.getAsInt();
+ }
+
+ /**
+ * Return the contained value, if present, otherwise throw an exception
+ * to be created by the provided supplier.
+ *
+ * @apiNote A method reference to the exception constructor with an empty
+ * argument list can be used as the supplier. For example,
+ * {@code IllegalStateException::new}
+ *
+ * @param <X> Type of the exception to be thrown
+ * @param exceptionSupplier The supplier which will return the exception to
+ * be thrown
+ * @return the present value
+ * @throws X if there is no value present
+ * @throws NullPointerException if no value is present and
+ * {@code exceptionSupplier} is null
+ */
+ public<X extends Throwable> int orElseThrow(Supplier<X> exceptionSupplier) throws X {
+ if (isPresent) {
+ return value;
+ } else {
+ throw exceptionSupplier.get();
+ }
+ }
+
+ /**
+ * Indicates whether some other object is "equal to" this Optional. The
+ * other object is considered equal if:
+ * <ul>
+ * <li>it is also an {@code OptionalInt} and;
+ * <li>both instances have no value present or;
+ * <li>the present values are "equal to" each other via {@code ==}.
+ * </ul>
+ *
+ * @param obj an object to be tested for equality
+ * @return {code true} if the other object is "equal to" this object
+ * otherwise {@code false}
+ */
+ @Override
+ public boolean equals(Object obj) {
+ if (this == obj) {
+ return true;
+ }
+
+ if (!(obj instanceof OptionalInt)) {
+ return false;
+ }
+
+ OptionalInt other = (OptionalInt) obj;
+ return (isPresent && other.isPresent)
+ ? value == other.value
+ : isPresent == other.isPresent;
+ }
+
+ /**
+ * Returns the hash code value of the present value, if any, or 0 (zero) if
+ * no value is present.
+ *
+ * @return hash code value of the present value or 0 if no value is present
+ */
+ @Override
+ public int hashCode() {
+ return isPresent ? Integer.hashCode(value) : 0;
+ }
+
+ /**
+ * Returns a non-empty string representation of this OptionalInt suitable for
+ * debugging. The exact presentation format is unspecified and may vary
+ * between implementations and versions.
+ *
+ * @implSpec If a value is present the result must include its string
+ * representation in the result. Empty and present OptionalInts must be
+ * unambiguously differentiable.
+ *
+ * @return the string representation of this instance
+ */
+ @Override
+ public String toString() {
+ return isPresent
+ ? String.format("OptionalInt[%s]", value)
+ : "OptionalInt.empty";
+ }
+}