Java tutorial
/* * Copyright (c) 2016 Gridtec. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package at.gridtec.lambda4j.predicate.bi; import at.gridtec.lambda4j.Lambda; import at.gridtec.lambda4j.consumer.ThrowableBooleanConsumer; import at.gridtec.lambda4j.consumer.bi.ThrowableBiConsumer; import at.gridtec.lambda4j.core.exception.ThrownByFunctionalInterfaceException; import at.gridtec.lambda4j.core.util.ThrowableUtils; import at.gridtec.lambda4j.function.ThrowableBooleanFunction; import at.gridtec.lambda4j.function.ThrowableFunction; import at.gridtec.lambda4j.function.bi.ThrowableBiFunction; import at.gridtec.lambda4j.function.bi.to.ThrowableToByteBiFunction; import at.gridtec.lambda4j.function.bi.to.ThrowableToCharBiFunction; import at.gridtec.lambda4j.function.bi.to.ThrowableToDoubleBiFunction; import at.gridtec.lambda4j.function.bi.to.ThrowableToFloatBiFunction; import at.gridtec.lambda4j.function.bi.to.ThrowableToIntBiFunction; import at.gridtec.lambda4j.function.bi.to.ThrowableToLongBiFunction; import at.gridtec.lambda4j.function.bi.to.ThrowableToShortBiFunction; import at.gridtec.lambda4j.function.conversion.ThrowableBooleanToByteFunction; import at.gridtec.lambda4j.function.conversion.ThrowableBooleanToCharFunction; import at.gridtec.lambda4j.function.conversion.ThrowableBooleanToDoubleFunction; import at.gridtec.lambda4j.function.conversion.ThrowableBooleanToFloatFunction; import at.gridtec.lambda4j.function.conversion.ThrowableBooleanToIntFunction; import at.gridtec.lambda4j.function.conversion.ThrowableBooleanToLongFunction; import at.gridtec.lambda4j.function.conversion.ThrowableBooleanToShortFunction; import at.gridtec.lambda4j.operator.unary.ThrowableBooleanUnaryOperator; import at.gridtec.lambda4j.predicate.ThrowablePredicate; import org.apache.commons.lang3.tuple.Pair; import javax.annotation.Nonnegative; import javax.annotation.Nonnull; import javax.annotation.Nullable; import java.util.Map; import java.util.Objects; import java.util.concurrent.ConcurrentHashMap; import java.util.function.BiPredicate; import java.util.function.Function; /** * Represents an predicate (boolean-valued function) of two input arguments which is able to throw any {@link * Throwable}. * <p> * This is a {@link FunctionalInterface} whose functional method is {@link #testThrows(Object, Object)}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @apiNote This is a throwable JDK lambda. * @see ThrowableBiPredicate */ @SuppressWarnings("unused") @FunctionalInterface public interface ThrowableBiPredicate<T, U, X extends Throwable> extends Lambda, BiPredicate<T, U> { /** * Constructs a {@link ThrowableBiPredicate} based on a lambda expression or a method reference. Thereby the given * lambda expression or method reference is returned on an as-is basis to implicitly transform it to the desired * type. With this method, it is possible to ensure that correct type is used from lambda expression or method * reference. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @param expression A lambda expression or (typically) a method reference, e.g. {@code this::method} * @return A {@code ThrowableBiPredicate} from given lambda expression or method reference. * @implNote This implementation allows the given argument to be {@code null}, but only if {@code null} given, * {@code null} will be returned. * @see <a href="https://docs.oracle.com/javase/tutorial/java/javaOO/lambdaexpressions.html#syntax">Lambda * Expression</a> * @see <a href="https://docs.oracle.com/javase/tutorial/java/javaOO/methodreferences.html">Method Reference</a> */ static <T, U, X extends Throwable> ThrowableBiPredicate<T, U, X> of( @Nullable final ThrowableBiPredicate<T, U, X> expression) { return expression; } /** * Calls the given {@link ThrowableBiPredicate} with the given arguments and returns its result. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @param predicate The predicate to be called * @param t The first argument to the predicate * @param u The second argument to the predicate * @return The result from the given {@code ThrowableBiPredicate}. * @throws NullPointerException If given argument is {@code null} * @throws X Any throwable from this predicates action */ static <T, U, X extends Throwable> boolean call( @Nonnull final ThrowableBiPredicate<? super T, ? super U, ? extends X> predicate, T t, U u) throws X { Objects.requireNonNull(predicate); return predicate.testThrows(t, u); } /** * Creates a {@link ThrowableBiPredicate} which uses the {@code first} parameter of this one as argument for the * given {@link ThrowablePredicate}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @param predicate The predicate which accepts the {@code first} parameter of this one * @return Creates a {@code ThrowableBiPredicate} which uses the {@code first} parameter of this one as argument for * the given {@code ThrowablePredicate}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static <T, U, X extends Throwable> ThrowableBiPredicate<T, U, X> onlyFirst( @Nonnull final ThrowablePredicate<? super T, ? extends X> predicate) { Objects.requireNonNull(predicate); return (t, u) -> predicate.testThrows(t); } /** * Creates a {@link ThrowableBiPredicate} which uses the {@code second} parameter of this one as argument for the * given {@link ThrowablePredicate}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @param predicate The predicate which accepts the {@code second} parameter of this one * @return Creates a {@code ThrowableBiPredicate} which uses the {@code second} parameter of this one as argument * for the given {@code ThrowablePredicate}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static <T, U, X extends Throwable> ThrowableBiPredicate<T, U, X> onlySecond( @Nonnull final ThrowablePredicate<? super U, ? extends X> predicate) { Objects.requireNonNull(predicate); return (t, u) -> predicate.testThrows(u); } /** * Creates a {@link ThrowableBiPredicate} which always returns a given value. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @param ret The return value for the constant * @return A {@code ThrowableBiPredicate} which always returns a given value. */ @Nonnull static <T, U, X extends Throwable> ThrowableBiPredicate<T, U, X> constant(boolean ret) { return (t, u) -> ret; } /** * Returns a {@link ThrowableBiPredicate} that always returns {@code true}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @return A {@link ThrowableBiPredicate} that always returns {@code true}. * @see #alwaysFalse() */ @Nonnull static <T, U, X extends Throwable> ThrowableBiPredicate<T, U, X> alwaysTrue() { return (t, u) -> true; } /** * Returns a {@link ThrowableBiPredicate} that always returns {@code false}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @return A {@link ThrowableBiPredicate} that always returns {@code false}. * @see #alwaysTrue() */ @Nonnull static <T, U, X extends Throwable> ThrowableBiPredicate<T, U, X> alwaysFalse() { return (t, u) -> false; } /** * Returns a {@link ThrowableBiPredicate} that tests if the given arguments are <b>equal</b> to the ones of this * predicate. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param <X> The type of the throwable to be thrown by this predicate * @param target1 The first reference with which to compare for equality, which may be {@code null} * @param target2 The second reference with which to compare for equality, which may be {@code null} * @return A {@code ThrowableBiPredicate} that tests if the given arguments are <b>equal</b> to the ones of this * predicate. * @implNote This implementation checks equality according to {@link Objects#equals(Object)} operation for {@link * Object} references and {@code value == target} operation for primitive values. */ @Nonnull static <T, U, X extends Throwable> ThrowableBiPredicate<T, U, X> isEqual(@Nullable Object target1, @Nullable Object target2) { return (t, u) -> (t == null ? target1 == null : t.equals(target1)) && (u == null ? target2 == null : u.equals(target2)); } /** * Applies this predicate to the given arguments. * * @param t The first argument to the predicate * @param u The second argument to the predicate * @return The return value from the predicate, which is its result. * @throws X Any throwable from this predicates action */ boolean testThrows(T t, U u) throws X; /** * Applies this predicate to the given arguments. * * @param t The first argument to the predicate * @param u The second argument to the predicate * @return The return value from the predicate, which is its result. * @apiNote This method mainly exists to use this {@link ThrowableBiPredicate} in JRE specific methods only * accepting {@link BiPredicate}. If this predicate should be applied, then the {@link #testThrows(Object, Object)} * method should be used. * @apiNote Overrides the {@link BiPredicate#test(Object, Object)} method by using a redefinition as default method. * This implementation calls the {@link #testThrows(Object, Object)} method of this function and catches the * eventually thrown {@link Throwable} from it. If it is of type {@link RuntimeException} or {@link Error} it is * rethrown as is. Other {@code Throwable} types are wrapped in a {@link ThrownByFunctionalInterfaceException}. */ @Override default boolean test(T t, U u) { // TODO: Remove commented code below /*try { return this.testThrows(t, u); } catch (RuntimeException | Error e) { throw e; } catch (Throwable throwable) { throw new ThrownByFunctionalInterfaceException(throwable.getMessage(), throwable); }*/ return nest().test(t, u); } /** * Applies this predicate to the given tuple. * * @param tuple The tuple to be applied to the predicate * @return The return value from the predicate, which is its result. * @throws NullPointerException If given argument is {@code null} * @throws X Any throwable from this predicates action * @see org.apache.commons.lang3.tuple.Pair */ default boolean testThrows(@Nonnull Pair<T, U> tuple) throws X { Objects.requireNonNull(tuple); return testThrows(tuple.getLeft(), tuple.getRight()); } /** * Applies this predicate partially to some arguments of this one, producing a {@link ThrowablePredicate} as result. * * @param t The first argument to this predicate used to partially apply this function * @return A {@code ThrowablePredicate} that represents this predicate partially applied the some arguments. */ @Nonnull default ThrowablePredicate<U, X> ptestThrows(T t) { return (u) -> this.testThrows(t, u); } /** * Returns the number of arguments for this predicate. * * @return The number of arguments for this predicate. * @implSpec The default implementation always returns {@code 2}. */ @Nonnegative default int arity() { return 2; } /** * Returns a composed {@link ThrowableBiPredicate} that first applies the {@code before} functions to its input, and * then applies this predicate to the result. * * @param <A> The type of the argument to the first given function, and of composed predicate * @param <B> The type of the argument to the second given function, and of composed predicate * @param before1 The first function to apply before this predicate is applied * @param before2 The second function to apply before this predicate is applied * @return A composed {@code ThrowableBiPredicate} that first applies the {@code before} functions to its input, and * then applies this predicate to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is able to handle every type. */ @Nonnull default <A, B> ThrowableBiPredicate<A, B, X> compose( @Nonnull final ThrowableFunction<? super A, ? extends T, ? extends X> before1, @Nonnull final ThrowableFunction<? super B, ? extends U, ? extends X> before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (a, b) -> testThrows(before1.applyThrows(a), before2.applyThrows(b)); } /** * Returns a composed {@link ThrowableBiFunction} that first applies this predicate to its input, and then applies * the {@code after} function to the result. * * @param <S> The type of return value from the {@code after} function, and of the composed function * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableBiFunction} that first applies this predicate to its input, and then applies * the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is able to return every type. */ @Nonnull default <S> ThrowableBiFunction<T, U, S, X> andThen( @Nonnull final ThrowableBooleanFunction<? extends S, ? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableBiPredicate} that first applies this predicate to its input, and then applies * the {@code after} operator to the result. This method is just convenience, to provide the ability to transform * this primitive predicate to an operation returning {@code boolean}. * * @param after The operator to apply after this predicate is applied * @return A composed {@code ThrowableBiPredicate} that first applies this predicate to its input, and then applies * the {@code after} operator to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * boolean}. */ @Nonnull default ThrowableBiPredicate<T, U, X> andThenToBoolean( @Nonnull final ThrowableBooleanUnaryOperator<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsBooleanThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableToByteBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. This method is just convenience, to provide the ability to * transform this primitive predicate to an operation returning {@code byte}. * * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableToByteBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * byte}. */ @Nonnull default ThrowableToByteBiFunction<T, U, X> andThenToByte( @Nonnull final ThrowableBooleanToByteFunction<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsByteThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableToCharBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. This method is just convenience, to provide the ability to * transform this primitive predicate to an operation returning {@code char}. * * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableToCharBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * char}. */ @Nonnull default ThrowableToCharBiFunction<T, U, X> andThenToChar( @Nonnull final ThrowableBooleanToCharFunction<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsCharThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableToDoubleBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. This method is just convenience, to provide the ability to * transform this primitive predicate to an operation returning {@code double}. * * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableToDoubleBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * double}. */ @Nonnull default ThrowableToDoubleBiFunction<T, U, X> andThenToDouble( @Nonnull final ThrowableBooleanToDoubleFunction<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsDoubleThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableToFloatBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. This method is just convenience, to provide the ability to * transform this primitive predicate to an operation returning {@code float}. * * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableToFloatBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * float}. */ @Nonnull default ThrowableToFloatBiFunction<T, U, X> andThenToFloat( @Nonnull final ThrowableBooleanToFloatFunction<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsFloatThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableToIntBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. This method is just convenience, to provide the ability to * transform this primitive predicate to an operation returning {@code int}. * * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableToIntBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * int}. */ @Nonnull default ThrowableToIntBiFunction<T, U, X> andThenToInt( @Nonnull final ThrowableBooleanToIntFunction<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsIntThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableToLongBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. This method is just convenience, to provide the ability to * transform this primitive predicate to an operation returning {@code long}. * * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableToLongBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * long}. */ @Nonnull default ThrowableToLongBiFunction<T, U, X> andThenToLong( @Nonnull final ThrowableBooleanToLongFunction<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsLongThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableToShortBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. This method is just convenience, to provide the ability to * transform this primitive predicate to an operation returning {@code short}. * * @param after The function to apply after this predicate is applied * @return A composed {@code ThrowableToShortBiFunction} that first applies this predicate to its input, and then * applies the {@code after} function to the result. * @throws NullPointerException If given argument is {@code null} * @implSpec The input argument of this method is a able to return primitive values. In this case this is {@code * short}. */ @Nonnull default ThrowableToShortBiFunction<T, U, X> andThenToShort( @Nonnull final ThrowableBooleanToShortFunction<? extends X> after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsShortThrows(testThrows(t, u)); } /** * Returns a composed {@link ThrowableBiConsumer} that fist applies this predicate to its input, and then consumes * the result using the given {@link ThrowableBooleanConsumer}. * * @param consumer The operation which consumes the result from this operation * @return A composed {@code ThrowableBiConsumer} that first applies this predicate to its input, and then consumes * the result using the given {@code ThrowableBooleanConsumer}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull default ThrowableBiConsumer<T, U, X> consume(@Nonnull final ThrowableBooleanConsumer<? extends X> consumer) { Objects.requireNonNull(consumer); return (t, u) -> consumer.acceptThrows(testThrows(t, u)); } /** * Returns a {@link ThrowableBiPredicate} that represents the logical negation of this one. * * @return A {@code ThrowableBiPredicate} that represents the logical negation of this one. */ @Nonnull default ThrowableBiPredicate<T, U, X> negate() { return (t, u) -> !testThrows(t, u); } /** * Returns a composed {@link ThrowableBiPredicate} that represents a short-circuiting logical AND of this predicate * and another. When evaluating the composed predicate, if this predicate is {@code false}, then the {@code other} * predicate is not evaluated. * <p> * Any exceptions thrown during evaluation of either predicate is relayed to the caller; if evaluation of this * {@code ThrowableBiPredicate} throws an exception, the {@code other} predicate will not be evaluated. * * @param other A {@code ThrowableBiPredicate} that will be logically-ANDed with this one * @return A composed {@code ThrowableBiPredicate} that represents the short-circuiting logical AND of this * predicate and the {@code other} predicate. * @throws NullPointerException If given argument is {@code null} * @see #or(ThrowableBiPredicate) * @see #xor(ThrowableBiPredicate) */ @Nonnull default ThrowableBiPredicate<T, U, X> and( @Nonnull final ThrowableBiPredicate<? super T, ? super U, ? extends X> other) { Objects.requireNonNull(other); return (t, u) -> testThrows(t, u) && other.testThrows(t, u); } /** * Returns a composed {@link ThrowableBiPredicate} that represents a short-circuiting logical OR of this predicate * and another. When evaluating the composed predicate, if this predicate is {@code true}, then the {@code other} * predicate is not evaluated. * <p> * Any exceptions thrown during evaluation of either predicate is relayed to the caller; if evaluation of this * {@code ThrowableBiPredicate} throws an exception, the {@code other} predicate will not be evaluated. * * @param other A {@code ThrowableBiPredicate} that will be logically-ORed with this one * @return A composed {@code ThrowableBiPredicate} that represents the short-circuiting logical OR of this predicate * and the {@code other} predicate. * @throws NullPointerException If given argument is {@code null} * @see #and(ThrowableBiPredicate) * @see #xor(ThrowableBiPredicate) */ @Nonnull default ThrowableBiPredicate<T, U, X> or( @Nonnull final ThrowableBiPredicate<? super T, ? super U, ? extends X> other) { Objects.requireNonNull(other); return (t, u) -> testThrows(t, u) || other.testThrows(t, u); } /** * Returns a composed {@link ThrowableBiPredicate} that represents a short-circuiting logical XOR of this predicate * and another. Any exceptions thrown during evaluation of either predicate is relayed to the caller; if evaluation * of this {@code ThrowableBiPredicate} throws an exception, the {@code other} predicate will not be evaluated. * * @param other A {@code ThrowableBiPredicate} that will be logically-XORed with this one * @return A composed {@code ThrowableBiPredicate} that represents the short-circuiting logical XOR of this * predicate and the {@code other} predicate. * @throws NullPointerException If given argument is {@code null} * @see #and(ThrowableBiPredicate) * @see #or(ThrowableBiPredicate) */ @Nonnull default ThrowableBiPredicate<T, U, X> xor( @Nonnull final ThrowableBiPredicate<? super T, ? super U, ? extends X> other) { Objects.requireNonNull(other); return (t, u) -> testThrows(t, u) ^ other.testThrows(t, u); } /** * Returns a tupled version of this predicate. * * @return A tupled version of this predicate. */ @Nonnull default ThrowablePredicate<Pair<T, U>, X> tupled() { return this::testThrows; } /** * Returns a reversed version of this predicate. This may be useful in recursive context. * * @return A reversed version of this predicate. */ @Nonnull default ThrowableBiPredicate<U, T, X> reversed() { return (u, t) -> testThrows(t, u); } /** * Returns a memoized (caching) version of this {@link ThrowableBiPredicate}. Whenever it is called, the mapping * between the input parameters and the return value is preserved in a cache, making subsequent calls returning the * memoized value instead of computing the return value again. * <p> * Unless the predicate and therefore the used cache will be garbage-collected, it will keep all memoized values * forever. * * @return A memoized (caching) version of this {@code ThrowableBiPredicate}. * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the * resulting memoized predicate, as the cache used internally does not permit {@code null} keys or values. * @implNote The returned memoized predicate can be safely used concurrently from multiple threads which makes it * thread-safe. */ @Nonnull default ThrowableBiPredicate<T, U, X> memoized() { if (isMemoized()) { return this; } else { final Map<Pair<T, U>, Boolean> cache = new ConcurrentHashMap<>(); final Object lock = new Object(); return (ThrowableBiPredicate<T, U, X> & Memoized) (t, u) -> { final boolean returnValue; synchronized (lock) { returnValue = cache.computeIfAbsent(Pair.of(t, u), ThrowableFunction.of(key -> testThrows(key.getLeft(), key.getRight()))); } return returnValue; }; } } /** * Returns a composed {@link BiPredicate2} that applies this predicate to its input and nests the thrown {@link * Throwable} from it. The {@code Throwable} is nested (wrapped) in a {@link ThrownByFunctionalInterfaceException}, * which is constructed from the thrown {@code Throwable}s message and the thrown {@code Throwable} itself. * * @return A composed {@link BiPredicate2} that applies this predicate to its input and nests the thrown {@code * Throwable} from it. * @implNote If thrown {@code Throwable} is of type {@link Error} it is thrown as-is and thus not nested. * @see #nestWith(Function) * @see ThrownByFunctionalInterfaceException */ @Nonnull default BiPredicate2<T, U> nest() { return nestWith(throwable -> new ThrownByFunctionalInterfaceException(throwable.getMessage(), throwable)); } /** * Returns a composed {@link BiPredicate2} that applies this predicate to its input and nests the thrown {@link * Throwable} from it using {@code mapper} operation. Thereby {@code mapper} may modify the thrown {@code * Throwable}, regarding its implementation, and returns it nested (wrapped) in a {@link RuntimeException}. * * @param mapper The operation to map the thrown {@code Throwable} to {@code RuntimeException} * @return A composed {@link BiPredicate2} that applies this predicate to its input and nests the thrown {@code * Throwable} from it using {@code mapper} operation. * @throws NullPointerException If given argument is {@code null} * @implNote If thrown {@code Throwable} is of type {@link Error} it is thrown as-is and thus not nested. * @see #nest() */ @Nonnull default BiPredicate2<T, U> nestWith( @Nonnull final Function<? super Throwable, ? extends RuntimeException> mapper) { return recover(throwable -> { throw mapper.apply(throwable); }); } /** * Returns a composed {@link BiPredicate2} that applies this predicate to its input and sneakily throws the * thrown {@link Throwable} from it, if it is not of type {@link RuntimeException} or {@link Error}. This means that * each throwable thrown from the returned composed predicate behaves exactly the same as an <em>unchecked</em> * throwable does. As a result, there is no need to handle the throwable of this predicate in the returned composed * predicate by either wrapping it in an <em>unchecked</em> throwable or to declare it in the {@code throws} clause, * as it would be done in a non sneaky throwing predicate. * <p> * What sneaky throwing simply does, is to fake out the compiler and thus it bypasses the principle of * <em>checked</em> throwables. On the JVM (class file) level, all throwables, checked or not, can be thrown * regardless of the {@code throws} clause of methods, which is why this works at all. * <p> * However, when using this method to get a sneaky throwing predicate variant of this throwable predicate, the * following advantages, disadvantages and limitations will apply: * <p> * If the calling-code is to handle the sneakily thrown throwable, it is required to add it to the {@code throws} * clause of the method that applies the returned composed predicate. The compiler will not force the declaration in * the {@code throws} clause anymore. * <p> * If the calling-code already handles the sneakily thrown throwable, the compiler requires it to be added to the * {@code throws} clause of the method that applies the returned composed predicate. If not added, the compiler will * error that the caught throwable is never thrown in the corresponding {@code try} block. * <p> * If the returned composed predicate is directly surrounded by a {@code try}-{@code catch} block to catch the * sneakily thrown throwable from it, the compiler will error that the caught throwable is never thrown in the * corresponding {@code try} block. * <p> * In any case, if the throwable is not added to the to the {@code throws} clause of the method that applies the * returned composed predicate, the calling-code won't be able to catch the throwable by name. It will bubble and * probably be caught in some {@code catch} statement, catching a base type such as {@code try { ... } * catch(RuntimeException e) { ... }} or {@code try { ... } catch(Exception e) { ... }}, but perhaps this is * intended. * <p> * When the called code never throws the specific throwable that it declares, it should obviously be omitted. For * example: {@code new String(byteArr, "UTF-8") throws UnsupportedEncodingException}, but {@code UTF-8} is * guaranteed by the Java specification to be always present. Here, the {@code throws} declaration is a nuisance and * any solution to silence it with minimal boilerplate is welcome. The throwable should therefore be omitted in the * {@code throws} clause of the method that applies the returned composed predicate. * <p> * With all that mentioned, the following example will demonstrate this methods correct use: * <pre>{@code * // when called with illegal value ClassNotFoundException is thrown * public Class<?> sneakyThrowingFunctionalInterface(final String className) throws ClassNotFoundException { * return ThrowableFunction.of(Class::forName) // create the correct throwable functional interface * .sneakyThrow() // create a non-throwable variant which is able to sneaky throw (this method) * .apply(className); // apply non-throwable variant -> may sneaky throw a throwable * } * * // call the the method which surround the sneaky throwing functional interface * public void callingMethod() { * try { * final Class<?> clazz = sneakyThrowingFunctionalInterface("some illegal class name"); * // ... do something with clazz ... * } catch(ClassNotFoundException e) { * // ... do something with e ... * } * } * }</pre> * In conclusion, this somewhat contentious ability should be used carefully, of course, with the advantages, * disadvantages and limitations described above kept in mind. * * @return A composed {@link BiPredicate2} that applies this predicate to its input and sneakily throws the thrown * {@link Throwable} from it, unless it is of type {@link RuntimeException} or {@link Error}. * @implNote If thrown {@link Throwable} is of type {@link RuntimeException} or {@link Error}, it is thrown as-is * and thus not sneakily thrown. */ @Nonnull default BiPredicate2<T, U> sneakyThrow() { return (t, u) -> { try { return this.testThrows(t, u); } catch (RuntimeException | Error e) { throw e; } catch (Throwable throwable) { throw ThrowableUtils.sneakyThrow(throwable); } }; } /** * Returns a composed {@link BiPredicate2} that first applies this predicate to its input, and then applies the * {@code recover} operation if a {@link Throwable} is thrown from this one. The {@code recover} operation is * represented by a curried operation which is called with throwable information and same arguments of this * predicate. * * @param recover The operation to apply if this predicate throws a {@code Throwable} * @return A composed {@link BiPredicate2} that first applies this predicate to its input, and then applies the * {@code recover} operation if a {@code Throwable} is thrown from this one. * @throws NullPointerException If given argument or the returned enclosing predicate is {@code null} * @implSpec The implementation checks that the returned enclosing predicate from {@code recover} operation is not * {@code null}. If it is, then a {@link NullPointerException} with appropriate message is thrown. * @implNote If thrown {@code Throwable} is of type {@link Error}, it is thrown as-is and thus not passed to {@code * recover} operation. */ @Nonnull default BiPredicate2<T, U> recover( @Nonnull final Function<? super Throwable, ? extends BiPredicate<? super T, ? super U>> recover) { Objects.requireNonNull(recover); return (t, u) -> { try { return this.testThrows(t, u); } catch (Error e) { throw e; } catch (Throwable throwable) { final BiPredicate<? super T, ? super U> predicate = recover.apply(throwable); Objects.requireNonNull(predicate, () -> "recover returned null for " + throwable.getClass() + ": " + throwable.getMessage()); return predicate.test(t, u); } }; } }