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.function.bi.to; import at.gridtec.lambda4j.Lambda; import at.gridtec.lambda4j.consumer.ByteConsumer; import at.gridtec.lambda4j.consumer.bi.BiConsumer2; import at.gridtec.lambda4j.function.ByteFunction; import at.gridtec.lambda4j.function.bi.BiFunction2; import at.gridtec.lambda4j.function.conversion.ByteToCharFunction; import at.gridtec.lambda4j.function.conversion.ByteToDoubleFunction; import at.gridtec.lambda4j.function.conversion.ByteToFloatFunction; import at.gridtec.lambda4j.function.conversion.ByteToIntFunction; import at.gridtec.lambda4j.function.conversion.ByteToLongFunction; import at.gridtec.lambda4j.function.conversion.ByteToShortFunction; import at.gridtec.lambda4j.function.to.ToByteFunction; import at.gridtec.lambda4j.operator.unary.ByteUnaryOperator; import at.gridtec.lambda4j.predicate.BytePredicate; import at.gridtec.lambda4j.predicate.bi.BiPredicate2; 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.Function; /** * Represents an operation that accepts two input arguments and produces a * {@code byte}-valued result. * This is a primitive specialization of {@link BiFunction2}. * <p> * This is a {@link FunctionalInterface} whose functional method is {@link #applyAsByte(Object, Object)}. * * @param <T> The type of the first argument to the function * @param <U> The type of the second argument to the function * @see BiFunction2 */ @SuppressWarnings("unused") @FunctionalInterface public interface ToByteBiFunction<T, U> extends Lambda { /** * Constructs a {@link ToByteBiFunction} 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 function * @param <U> The type of the second argument to the function * @param expression A lambda expression or (typically) a method reference, e.g. {@code this::method} * @return A {@code ToByteBiFunction} 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> ToByteBiFunction<T, U> of(@Nullable final ToByteBiFunction<T, U> expression) { return expression; } /** * Calls the given {@link ToByteBiFunction} with the given arguments and returns its result. * * @param <T> The type of the first argument to the function * @param <U> The type of the second argument to the function * @param function The function to be called * @param t The first argument to the function * @param u The second argument to the function * @return The result from the given {@code ToByteBiFunction}. * @throws NullPointerException If given argument is {@code null} */ static <T, U> byte call(@Nonnull final ToByteBiFunction<? super T, ? super U> function, T t, U u) { Objects.requireNonNull(function); return function.applyAsByte(t, u); } /** * Creates a {@link ToByteBiFunction} which uses the {@code first} parameter of this one as argument for the given * {@link ToByteFunction}. * * @param <T> The type of the first argument to the function * @param <U> The type of the second argument to the function * @param function The function which accepts the {@code first} parameter of this one * @return Creates a {@code ToByteBiFunction} which uses the {@code first} parameter of this one as argument for the * given {@code ToByteFunction}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static <T, U> ToByteBiFunction<T, U> onlyFirst(@Nonnull final ToByteFunction<? super T> function) { Objects.requireNonNull(function); return (t, u) -> function.applyAsByte(t); } /** * Creates a {@link ToByteBiFunction} which uses the {@code second} parameter of this one as argument for the given * {@link ToByteFunction}. * * @param <T> The type of the first argument to the function * @param <U> The type of the second argument to the function * @param function The function which accepts the {@code second} parameter of this one * @return Creates a {@code ToByteBiFunction} which uses the {@code second} parameter of this one as argument for * the given {@code ToByteFunction}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull static <T, U> ToByteBiFunction<T, U> onlySecond(@Nonnull final ToByteFunction<? super U> function) { Objects.requireNonNull(function); return (t, u) -> function.applyAsByte(u); } /** * Creates a {@link ToByteBiFunction} which always returns a given value. * * @param <T> The type of the first argument to the function * @param <U> The type of the second argument to the function * @param ret The return value for the constant * @return A {@code ToByteBiFunction} which always returns a given value. */ @Nonnull static <T, U> ToByteBiFunction<T, U> constant(byte ret) { return (t, u) -> ret; } /** * Applies this function to the given arguments. * * @param t The first argument to the function * @param u The second argument to the function * @return The return value from the function, which is its result. */ byte applyAsByte(T t, U u); /** * Applies this function to the given tuple. * * @param tuple The tuple to be applied to the function * @return The return value from the function, which is its result. * @throws NullPointerException If given argument is {@code null} * @see org.apache.commons.lang3.tuple.Pair */ default byte applyAsByte(@Nonnull Pair<T, U> tuple) { Objects.requireNonNull(tuple); return applyAsByte(tuple.getLeft(), tuple.getRight()); } /** * Applies this function partially to some arguments of this one, producing a {@link ToByteFunction} as result. * * @param t The first argument to this function used to partially apply this function * @return A {@code ToByteFunction} that represents this function partially applied the some arguments. */ @Nonnull default ToByteFunction<U> papplyAsByte(T t) { return (u) -> this.applyAsByte(t, u); } /** * Returns the number of arguments for this function. * * @return The number of arguments for this function. * @implSpec The default implementation always returns {@code 2}. */ @Nonnegative default int arity() { return 2; } /** * Returns a composed {@link ToByteBiFunction} that first applies the {@code before} functions to its input, and * then applies this function 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 function * @param <B> The type of the argument to the second given function, and of composed function * @param before1 The first function to apply before this function is applied * @param before2 The second function to apply before this function is applied * @return A composed {@code ToByteBiFunction} that first applies the {@code before} functions to its input, and * then applies this function 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> ToByteBiFunction<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) -> applyAsByte(before1.apply(a), before2.apply(b)); } /** * Returns a composed {@link BiFunction2} that first applies this function 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 function is applied * @return A composed {@code BiFunction2} that first applies this function 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 ByteFunction<? extends S> after) { Objects.requireNonNull(after); return (t, u) -> after.apply(applyAsByte(t, u)); } /** * Returns a composed {@link BiPredicate2} that first applies this function to its input, and then applies the * {@code after} predicate 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 function to an operation returning {@code boolean}. * * @param after The predicate to apply after this function is applied * @return A composed {@code BiPredicate2} that first applies this function to its input, and then applies the * {@code after} predicate 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 BytePredicate after) { Objects.requireNonNull(after); return (t, u) -> after.test(applyAsByte(t, u)); } /** * Returns a composed {@link ToByteBiFunction} that first applies this function 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 function to an operation returning {@code byte}. * * @param after The operator to apply after this function is applied * @return A composed {@code ToByteBiFunction} that first applies this function 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 * byte}. */ @Nonnull default ToByteBiFunction<T, U> andThenToByte(@Nonnull final ByteUnaryOperator after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsByte(applyAsByte(t, u)); } /** * Returns a composed {@link ToCharBiFunction} that first applies this function 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 function to an operation returning {@code char}. * * @param after The function to apply after this function is applied * @return A composed {@code ToCharBiFunction} that first applies this function 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 ByteToCharFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsChar(applyAsByte(t, u)); } /** * Returns a composed {@link ToDoubleBiFunction2} that first applies this function 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 function to an operation returning {@code double}. * * @param after The function to apply after this function is applied * @return A composed {@code ToDoubleBiFunction2} that first applies this function 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 ByteToDoubleFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsDouble(applyAsByte(t, u)); } /** * Returns a composed {@link ToFloatBiFunction} that first applies this function 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 function to an operation returning {@code float}. * * @param after The function to apply after this function is applied * @return A composed {@code ToFloatBiFunction} that first applies this function 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 ByteToFloatFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsFloat(applyAsByte(t, u)); } /** * Returns a composed {@link ToIntBiFunction2} that first applies this function 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 function to an operation returning {@code int}. * * @param after The function to apply after this function is applied * @return A composed {@code ToIntBiFunction2} that first applies this function 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 ByteToIntFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsInt(applyAsByte(t, u)); } /** * Returns a composed {@link ToLongBiFunction2} that first applies this function 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 function to an operation returning {@code long}. * * @param after The function to apply after this function is applied * @return A composed {@code ToLongBiFunction2} that first applies this function 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 ByteToLongFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsLong(applyAsByte(t, u)); } /** * Returns a composed {@link ToShortBiFunction} that first applies this function 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 function to an operation returning {@code short}. * * @param after The function to apply after this function is applied * @return A composed {@code ToShortBiFunction} that first applies this function 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 ByteToShortFunction after) { Objects.requireNonNull(after); return (t, u) -> after.applyAsShort(applyAsByte(t, u)); } /** * Returns a composed {@link BiConsumer2} that fist applies this function to its input, and then consumes the result * using the given {@link ByteConsumer}. * 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 function to its input, and then consumes the * result using the given {@code ByteConsumer}. * @throws NullPointerException If given argument is {@code null} */ @Nonnull default BiConsumer2<T, U> consume(@Nonnull final ByteConsumer consumer) { Objects.requireNonNull(consumer); return (t, u) -> consumer.accept(applyAsByte(t, u)); } /** * Returns a tupled version of this function. * * @return A tupled version of this function. */ @Nonnull default ToByteFunction<Pair<T, U>> tupled() { return this::applyAsByte; } /** * Returns a reversed version of this function. This may be useful in recursive context. * * @return A reversed version of this function. */ @Nonnull default ToByteBiFunction<U, T> reversed() { return (u, t) -> applyAsByte(t, u); } /** * Returns a memoized (caching) version of this {@link ToByteBiFunction}. 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 function and therefore the used cache will be garbage-collected, it will keep all memoized values * forever. * * @return A memoized (caching) version of this {@code ToByteBiFunction}. * @implSpec This implementation does not allow the input parameters or return value to be {@code null} for the * resulting memoized function, as the cache used internally does not permit {@code null} keys or values. * @implNote The returned memoized function can be safely used concurrently from multiple threads which makes it * thread-safe. */ @Nonnull default ToByteBiFunction<T, U> memoized() { if (isMemoized()) { return this; } else { final Map<Pair<T, U>, Byte> cache = new ConcurrentHashMap<>(); final Object lock = new Object(); return (ToByteBiFunction<T, U> & Memoized) (t, u) -> { final byte returnValue; synchronized (lock) { returnValue = cache.computeIfAbsent(Pair.of(t, u), key -> applyAsByte(key.getLeft(), key.getRight())); } return returnValue; }; } } /** * Returns a composed {@link BiFunction2} which represents this {@link ToByteBiFunction}. Thereby the primitive * input argument for this function is autoboxed. This method provides the possibility to use this * {@code ToByteBiFunction} with methods provided by the {@code JDK}. * * @return A composed {@code BiFunction2} which represents this {@code ToByteBiFunction}. */ @Nonnull default BiFunction2<T, U, Byte> boxed() { return this::applyAsByte; } }