--- /dev/null
+/*
+ * Copyright (c) 2018 Pantheon Technologies, s.r.o. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.yangtools.concepts;
+
+import static java.util.Objects.requireNonNull;
+
+import com.google.common.annotations.Beta;
+import java.util.function.Consumer;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import javax.annotation.concurrent.ThreadSafe;
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.eclipse.jdt.annotation.Nullable;
+
+/**
+ * Utility holder similar to {@link java.util.Optional}, except the empty case contains an Exception, which should be
+ * reported, for example via throwing it. It provides analogous methods such as {@link #isPresent()},
+ * {@link #ifPresent(Consumer)}, {@link #get()}, {@link #orElse(Object)}, {@link #orElseGet(Supplier)},
+ * {@link #orElseThrow(Function)}.
+ *
+ * @param <T> Value type
+ * @param <E> Exception type
+ * @author Robert Varga
+ */
+@Beta
+@NonNullByDefault
+@ThreadSafe
+public final class CheckedValue<T, E extends Exception> extends Variant<T, E> {
+ private CheckedValue(final T value) {
+ super(value);
+ }
+
+ private CheckedValue(final E violation, final @Nullable Void dummy) {
+ super(violation, dummy);
+ }
+
+ /**
+ * Create a new instance containing an {@link Exception}.
+ *
+ * @param cause Throwable
+ * @return A new instance
+ * @throws NullPointerException if {@code cause} is null
+ */
+ public static <T, E extends Exception> CheckedValue<T, E> ofException(final E cause) {
+ return new CheckedValue<>(cause, null);
+ }
+
+ /**
+ * Create a new instance containing specified value.
+ *
+ * @param value Value
+ * @return A new instance
+ * @throws NullPointerException if {@code value} is null
+ */
+ public static <T, E extends Exception> CheckedValue<T, E> ofValue(final T value) {
+ return new CheckedValue<>(value);
+ }
+
+ /**
+ * Convert a Variant into a {@link CheckedValue}, converting the second value into an exception.
+ *
+ * @param variant Input variant
+ * @return Resulting {@link CheckedValue}
+ */
+ public static <T, U, E extends Exception> CheckedValue<T, E> ofVariant(final Variant<T, U> variant,
+ final Function<U, E> mapper) {
+ requireNonNull(mapper);
+ return variant.isFirst() ? new CheckedValue(variant.first())
+ : new CheckedValue(mapper.apply(variant.second()), null);
+ }
+
+ /**
+ * Return the contained value if {@link #isPresent()} would return true, throws {@link IllegalStateException}
+ * otherwise.
+ *
+ * @return Contained value
+ * @throws IllegalStateException if an error string is present.
+ */
+ public T get() {
+ if (isFirst()) {
+ return first();
+ }
+ throw new IllegalStateException("Value is not present", second());
+ }
+
+ /**
+ * Return the contained error string if {@link #isPresent()} would return false, throws
+ * {@link IllegalStateException} otherwise.
+ *
+ * @return Throwable which was used to instantiate this object, or absent if it was instantiated using an error
+ * string.
+ * @throws IllegalStateException if a value is present.
+ */
+ public E getException() {
+ if (isSecond()) {
+ return second();
+ }
+ throw new IllegalStateException("Value " + first() + " is present");
+ }
+
+ /**
+ * Return true if a value is present.
+ *
+ * @return True if a value is present.
+ */
+ public boolean isPresent() {
+ return isFirst();
+ }
+
+ /**
+ * If a value is present, invoke the specified consumer with the value, 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(final Consumer<? super T> consumer) {
+ if (isFirst()) {
+ consumer.accept(first());
+ }
+ }
+
+ @SuppressWarnings("unchecked")
+ public <U> CheckedValue<U, E> map(final Function<? super T, U> mapper) {
+ requireNonNull(mapper);
+ return isFirst() ? new CheckedValue<>(mapper.apply(first())) : (CheckedValue<U, E>) this;
+ }
+
+ @SuppressWarnings("unchecked")
+ public <X extends Exception> CheckedValue<T, X> mapException(final Function<? super E, X> mapper) {
+ requireNonNull(mapper);
+ if (isFirst()) {
+ return (CheckedValue<T, X>) this;
+ }
+ return new CheckedValue<>(mapper.apply(second()), null);
+ }
+
+
+ @SuppressWarnings("unchecked")
+ public <U> CheckedValue<U, E> flatMap(final Function<? super T, CheckedValue<U, E>> mapper) {
+ requireNonNull(mapper);
+ return isFirst() ? requireNonNull(mapper.apply(first())) : (CheckedValue<U, E>) this;
+ }
+
+ /**
+ * Return contained value if present, otherwise return supplied value.
+ *
+ * @param other Replacement value
+ * @return Contained value or {code other}
+ */
+ public T orElse(final T other) {
+ return isFirst() ? first() : other;
+ }
+
+ /**
+ * Return contained value if present, otherwise return the value produced by a supplier.
+ *
+ * @param supplier Replacement value supplier
+ * @return Contained value or supplier's value
+ * @throws NullPointerException if {@code supplier} is null
+ */
+ public T orElseGet(final Supplier<T> supplier) {
+ requireNonNull(supplier);
+ return isFirst() ? first() : supplier.get();
+ }
+
+ public <X extends Throwable> T orElseThrow() throws E {
+ if (isFirst()) {
+ return first();
+ }
+ throw second();
+ }
+
+ public <X extends Throwable> T orElseThrow(final Function<E, X> exceptionMapper) throws X {
+ requireNonNull(exceptionMapper);
+ if (isFirst()) {
+ return first();
+ }
+ throw exceptionMapper.apply(second());
+ }
+
+ public <X extends Throwable> T orElseThrow(final Supplier<X> supplier) throws X {
+ requireNonNull(supplier);
+ if (isFirst()) {
+ return first();
+ }
+ throw supplier.get();
+ }
+}
Code Review / yangtools.git / blobdiff