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.BooleanConsumer; import at.gridtec.lambda4j.consumer.bi.BiConsumer2; import at.gridtec.lambda4j.function.BooleanFunction; import at.gridtec.lambda4j.function.bi.BiFunction2; import at.gridtec.lambda4j.function.bi.to.ToByteBiFunction; import at.gridtec.lambda4j.function.bi.to.ToCharBiFunction; import at.gridtec.lambda4j.function.bi.to.ToDoubleBiFunction2; import at.gridtec.lambda4j.function.bi.to.ToFloatBiFunction; import at.gridtec.lambda4j.function.bi.to.ToIntBiFunction2; import at.gridtec.lambda4j.function.bi.to.ToLongBiFunction2; import at.gridtec.lambda4j.function.bi.to.ToShortBiFunction; import at.gridtec.lambda4j.function.conversion.BooleanToByteFunction; import at.gridtec.lambda4j.function.conversion.BooleanToCharFunction; import at.gridtec.lambda4j.function.conversion.BooleanToDoubleFunction; import at.gridtec.lambda4j.function.conversion.BooleanToFloatFunction; import at.gridtec.lambda4j.function.conversion.BooleanToIntFunction; import at.gridtec.lambda4j.function.conversion.BooleanToLongFunction; import at.gridtec.lambda4j.function.conversion.BooleanToShortFunction; import at.gridtec.lambda4j.operator.unary.BooleanUnaryOperator; import at.gridtec.lambda4j.predicate.Predicate2; 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; import java.util.function.Predicate; /** * Represents an predicate (boolean-valued function) of two input arguments. * <p> * This is a {@link FunctionalInterface} whose functional method is {@link #test(Object, Object)}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @apiNote This is a JDK lambda. * @see BiPredicate2 */ @SuppressWarnings("unused") @FunctionalInterface public interface BiPredicate2<T, U> extends Lambda, BiPredicate<T, U> { /** * Constructs a {@link BiPredicate2} 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 expression A lambda expression or (typically) a method reference, e.g. {@code this::method} * @return A {@code BiPredicate2} 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> BiPredicate2<T, U> of(@Nullable final BiPredicate2<T, U> expression) { return expression; } /** * Calls the given {@link BiPredicate} 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 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 BiPredicate2}. * @throws NullPointerException If given argument is {@code null} */ static <T, U> boolean call(@Nonnull final BiPredicate<? super T, ? super U> predicate, T t, U u) { Objects.requireNonNull(predicate); return predicate.test(t, u); } /** * Creates a {@link BiPredicate2} which uses the {@code first} parameter of this one as argument for the given * {@link Predicate}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param predicate The predicate which accepts the {@code first} parameter of this one * @return Creates a {@code BiPredicate2} which uses the {@code first} parameter of this one as argument for the * given {@code Predicate}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static <T, U> BiPredicate2<T, U> onlyFirst(@Nonnull final Predicate<? super T> predicate) { Objects.requireNonNull(predicate); return (t, u) -> predicate.test(t); } /** * Creates a {@link BiPredicate2} which uses the {@code second} parameter of this one as argument for the given * {@link Predicate}. * * @param <T> The type of the first argument to the predicate * @param <U> The type of the second argument to the predicate * @param predicate The predicate which accepts the {@code second} parameter of this one * @return Creates a {@code BiPredicate2} which uses the {@code second} parameter of this one as argument for the * given {@code Predicate}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static <T, U> BiPredicate2<T, U> onlySecond(@Nonnull final Predicate<? super U> predicate) { Objects.requireNonNull(predicate); return (t, u) -> predicate.test(u); } /** * Creates a {@link BiPredicate2} 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 ret The return value for the constant * @return A {@code BiPredicate2} which always returns a given value. */ @Nonnull static <T, U> BiPredicate2<T, U> constant(boolean ret) { return (t, u) -> ret; } /** * Returns a {@link BiPredicate2} 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 * @return A {@link BiPredicate2} that always returns {@code true}. * @see #alwaysFalse() */ @Nonnull static <T, U> BiPredicate2<T, U> alwaysTrue() { return (t, u) -> true; } /** * Returns a {@link BiPredicate2} 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 * @return A {@link BiPredicate2} that always returns {@code false}. * @see #alwaysTrue() */ @Nonnull static <T, U> BiPredicate2<T, U> alwaysFalse() { return (t, u) -> false; } /** * Returns a {@link BiPredicate2} 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 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 BiPredicate2} 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> BiPredicate2<T, U> 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. */ boolean test(T t, U 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} * @see org.apache.commons.lang3.tuple.Pair */ default boolean test(@Nonnull Pair<T, U> tuple) { Objects.requireNonNull(tuple); return test(tuple.getLeft(), tuple.getRight()); } /** * Applies this predicate partially to some arguments of this one, producing a {@link Predicate2} as result. * * @param t The first argument to this predicate used to partially apply this function * @return A {@code Predicate2} that represents this predicate partially applied the some arguments. */ @Nonnull default Predicate2<U> ptest(T t) { return (u) -> this.test(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 BiPredicate2} that first applies the {@code before} functions to its input, and * then applies this predicate to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * * @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 BiPredicate2} 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> BiPredicate2<A, B> compose(@Nonnull final Function<? super A, ? extends T> before1, @Nonnull final Function<? super B, ? extends U> before2) { Objects.requireNonNull(before1); Objects.requireNonNull(before2); return (a, b) -> test(before1.apply(a), before2.apply(b)); } /** * Returns a composed {@link BiFunction2} that first applies this predicate to its input, and then applies the * {@code after} function to the result. * If evaluation of either operation throws an exception, it is relayed to the caller of the composed operation. * * @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 BiFunction2} 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> BiFunction2<T, U, S> andThen(@Nonnull final BooleanFunction<? extends S> after) { Objects.requireNonNull(after); return (t, u) -> after.apply(test(t, u)); } /** * Returns a composed {@link BiPredicate2} that first applies this predicate to its input, and then applies the * {@code after} operator to the result. If evaluation of either operation throws an exception, it is relayed to the * caller of the composed operation. 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 BiPredicate2} 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 BiPredicate2<T, U> andThenToBoolean(@Nonnull final BooleanUnaryOperator after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsBoolean(test(t, u)); } /** * Returns a composed {@link ToByteBiFunction} that first applies this predicate to its input, and then applies the * {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to the * caller of the composed operation. 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 ToByteBiFunction} 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 ToByteBiFunction<T, U> andThenToByte(@Nonnull final BooleanToByteFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsByte(test(t, u)); } /** * Returns a composed {@link ToCharBiFunction} that first applies this predicate to its input, and then applies the * {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to the * caller of the composed operation. 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 ToCharBiFunction} 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 ToCharBiFunction<T, U> andThenToChar(@Nonnull final BooleanToCharFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsChar(test(t, u)); } /** * Returns a composed {@link ToDoubleBiFunction2} that first applies this predicate to its input, and then applies * the {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to * the caller of the composed operation. 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 ToDoubleBiFunction2} 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 ToDoubleBiFunction2<T, U> andThenToDouble(@Nonnull final BooleanToDoubleFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsDouble(test(t, u)); } /** * Returns a composed {@link ToFloatBiFunction} that first applies this predicate to its input, and then applies the * {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to the * caller of the composed operation. 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 ToFloatBiFunction} 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 ToFloatBiFunction<T, U> andThenToFloat(@Nonnull final BooleanToFloatFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsFloat(test(t, u)); } /** * Returns a composed {@link ToIntBiFunction2} that first applies this predicate to its input, and then applies the * {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to the * caller of the composed operation. 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 ToIntBiFunction2} 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 ToIntBiFunction2<T, U> andThenToInt(@Nonnull final BooleanToIntFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsInt(test(t, u)); } /** * Returns a composed {@link ToLongBiFunction2} that first applies this predicate to its input, and then applies the * {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to the * caller of the composed operation. 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 ToLongBiFunction2} 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 ToLongBiFunction2<T, U> andThenToLong(@Nonnull final BooleanToLongFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsLong(test(t, u)); } /** * Returns a composed {@link ToShortBiFunction} that first applies this predicate to its input, and then applies the * {@code after} function to the result. If evaluation of either operation throws an exception, it is relayed to the * caller of the composed operation. 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 ToShortBiFunction} 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 ToShortBiFunction<T, U> andThenToShort(@Nonnull final BooleanToShortFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsShort(test(t, u)); } /** * Returns a composed {@link BiConsumer2} that fist applies this predicate to its input, and then consumes the * result using the given {@link BooleanConsumer}. If evaluation of either operation throws an exception, it is * relayed to the caller of the composed operation. * * @param consumer The operation which consumes the result from this operation * @return A composed {@code BiConsumer2} that first applies this predicate to its input, and then consumes the * result using the given {@code BooleanConsumer}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull default BiConsumer2<T, U> consume(@Nonnull final BooleanConsumer consumer) { Objects.requireNonNull(consumer); return (t, u) -> consumer.accept(test(t, u)); } /** * Returns a {@link BiPredicate2} that represents the logical negation of this one. * * @return A {@code BiPredicate2} that represents the logical negation of this one. */ @Nonnull default BiPredicate2<T, U> negate() { return (t, u) -> !test(t, u); } /** * Returns a composed {@link BiPredicate2} 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 BiPredicate2} throws an exception, the {@code other} predicate will not be evaluated. * * @param other A {@code BiPredicate2} that will be logically-ANDed with this one * @return A composed {@code BiPredicate2} 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(BiPredicate) * @see #xor(BiPredicate) */ @Nonnull default BiPredicate2<T, U> and(@Nonnull final BiPredicate<? super T, ? super U> other) { Objects.requireNonNull(other); return (t, u) -> test(t, u) && other.test(t, u); } /** * Returns a composed {@link BiPredicate2} 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 BiPredicate2} throws an exception, the {@code other} predicate will not be evaluated. * * @param other A {@code BiPredicate2} that will be logically-ORed with this one * @return A composed {@code BiPredicate2} 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(BiPredicate) * @see #xor(BiPredicate) */ @Nonnull default BiPredicate2<T, U> or(@Nonnull final BiPredicate<? super T, ? super U> other) { Objects.requireNonNull(other); return (t, u) -> test(t, u) || other.test(t, u); } /** * Returns a composed {@link BiPredicate2} 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 BiPredicate2} throws an exception, the {@code other} predicate will not be evaluated. * * @param other A {@code BiPredicate2} that will be logically-XORed with this one * @return A composed {@code BiPredicate2} 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(BiPredicate) * @see #or(BiPredicate) */ @Nonnull default BiPredicate2<T, U> xor(@Nonnull final BiPredicate<? super T, ? super U> other) { Objects.requireNonNull(other); return (t, u) -> test(t, u) ^ other.test(t, u); } /** * Returns a tupled version of this predicate. * * @return A tupled version of this predicate. */ @Nonnull default Predicate2<Pair<T, U>> tupled() { return this::test; } /** * Returns a reversed version of this predicate. This may be useful in recursive context. * * @return A reversed version of this predicate. */ @Nonnull default BiPredicate2<U, T> reversed() { return (u, t) -> test(t, u); } /** * Returns a memoized (caching) version of this {@link BiPredicate2}. 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 BiPredicate2}. * @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 BiPredicate2<T, U> memoized() { if (isMemoized()) { return this; } else { final Map<Pair<T, U>, Boolean> cache = new ConcurrentHashMap<>(); final Object lock = new Object(); return (BiPredicate2<T, U> & Memoized) (t, u) -> { final boolean returnValue; synchronized (lock) { returnValue = cache.computeIfAbsent(Pair.of(t, u), key -> test(key.getLeft(), key.getRight())); } return returnValue; }; } } }