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fastutil extends the Java Collections Framework by providing type-specific maps, sets, lists and priority queues with a small memory footprint and fast access and insertion; provides also big (64-bit) arrays, sets and lists, and fast, practical I/O classes for binary and text files.

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/*
 * Copyright (C) 2002-2020 Sebastiano Vigna
 *
 * 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 PACKAGE;

import it.unimi.dsi.fastutil.Function;

/** A type-specific {@link Function}; provides some additional methods that use polymorphism to avoid (un)boxing.
 *
 * 

Type-specific versions of {@code get()}, {@code put()} and * {@code remove()} cannot rely on {@code null} to denote absence of * a key. Rather, they return a {@linkplain #defaultReturnValue() default * return value}, which is set to 0/false at creation, but can be changed using * the {@code defaultReturnValue()} method. * *

For uniformity reasons, even functions returning objects implement the default * return value (of course, in this case the default return value is * initialized to {@code null}). * *

The default implementation of optional operations just throw an {@link * UnsupportedOperationException}, except for the type-specific {@code * containsKey()}, which return true. Generic versions of accessors delegate to * the corresponding type-specific counterparts following the interface rules. * *

Warning: to fall in line as much as possible with the * {@linkplain java.util.Map standard map interface}, it is required that * standard versions of {@code get()}, {@code put()} and * {@code remove()} for maps with primitive-type keys or values return * {@code null} to denote missing keys rather than wrap the default * return value in an object. In case both keys and values are reference * types, the default return value must be returned instead, thus violating * the {@linkplain java.util.Map standard map interface} when the default * return value is not {@code null}. * * @see Function */ @FunctionalInterface #ifdef JDK_PRIMITIVE_FUNCTION public interface FUNCTION KEY_VALUE_GENERIC extends Function, JDK_PRIMITIVE_FUNCTION KEY_GENERIC VALUE_GENERIC { #else public interface FUNCTION KEY_VALUE_GENERIC extends Function { #endif #ifdef JDK_PRIMITIVE_FUNCTION #if KEY_WIDENED /** {@inheritDoc} * *

In this default implementation, the key gets narrowed down to the * actual key type, throwing an exception if the given key can't be * represented in the restricted domain. This is done for interoperability * with the Java 8 function environment. Its use is discouraged, as * unexpected errors can occur. Instead, the corresponding classes should be * used (e.g., {@link it.unimi.dsi.fastutil.ints.Int2IntFunction} instead of * {@link it.unimi.dsi.fastutil.shorts.Short2IntFunction}). * * @throws IllegalArgumentException If the given operand is not an element of the key domain. * @since 8.0.0 * @deprecated Please use primitive types which don't have to be widened as keys. */ @Deprecated #else /** {@inheritDoc} * @since 8.0.0 */ #endif @Override default VALUE_GENERIC_TYPE_WIDENED JDK_PRIMITIVE_FUNCTION_APPLY(KEY_GENERIC_TYPE_WIDENED operand) { return GET_VALUE(KEY_NARROWING(operand)); } #endif /** Adds a pair to the map (optional operation). * * @param key the key. * @param value the value. * @return the old value, or the {@linkplain #defaultReturnValue() default return value} if no value was present for the given key. * @see Function#put(Object,Object) */ default VALUE_GENERIC_TYPE put(final KEY_GENERIC_TYPE key, final VALUE_GENERIC_TYPE value) { throw new UnsupportedOperationException(); } /** Returns the value to which the given key is mapped. * * @param key the key. * @return the corresponding value, or the {@linkplain #defaultReturnValue() default return value} if no value was present for the given key. * @see Function#get(Object) */ VALUE_GENERIC_TYPE GET_VALUE(KEY_TYPE key); /** Removes the mapping with the given key (optional operation). * @param key the key. * @return the old value, or the {@linkplain #defaultReturnValue() default return value} if no value was present for the given key. * @see Function#remove(Object) */ default VALUE_GENERIC_TYPE REMOVE_VALUE(final KEY_TYPE key) { throw new UnsupportedOperationException(); } #if KEYS_PRIMITIVE || VALUES_PRIMITIVE /** {@inheritDoc} * @deprecated Please use the corresponding type-specific method instead. */ @Deprecated @Override default VALUE_GENERIC_CLASS put(final KEY_GENERIC_CLASS key, final VALUE_GENERIC_CLASS value) { final KEY_GENERIC_TYPE k = KEY_CLASS2TYPE(key); final boolean containsKey = containsKey(k); final VALUE_GENERIC_TYPE v = put(k, VALUE_CLASS2TYPE(value)); return containsKey ? VALUE2OBJ(v) : null; } /** {@inheritDoc} * @deprecated Please use the corresponding type-specific method instead. */ @Deprecated @Override default VALUE_GENERIC_CLASS get(final Object key) { #if KEYS_PRIMITIVE if (key == null) return null; #endif final KEY_TYPE k = KEY_OBJ2TYPE(key); final VALUE_GENERIC_TYPE v = GET_VALUE(k); return (v != defaultReturnValue() || containsKey(k)) ? VALUE2OBJ(v) : null; } /** {@inheritDoc} * @deprecated Please use the corresponding type-specific method instead. */ @Deprecated @Override default VALUE_GENERIC_CLASS remove(final Object key) { #if KEYS_PRIMITIVE if (key == null) return null; #endif final KEY_TYPE k = KEY_OBJ2TYPE(key); return containsKey(k) ? VALUE2OBJ(REMOVE_VALUE(k)) : null; } #if KEYS_PRIMITIVE /** Returns true if this function contains a mapping for the specified key. * *

Note that for some kind of functions (e.g., hashes) this method will * always return true. In particular, this default implementation always * returns true. * * @param key the key. * @return true if this function associates a value to {@code key}. * @see Function#containsKey(Object) */ default boolean containsKey(KEY_TYPE key) { return true; } /** {@inheritDoc} * @deprecated Please use the corresponding type-specific method instead. */ @Deprecated @Override default boolean containsKey(final Object key) { return key == null ? false : containsKey(KEY_OBJ2TYPE(key)); } #endif #endif /** Sets the default return value (optional operation). * * This value must be returned by type-specific versions of * {@code get()}, {@code put()} and {@code remove()} to * denote that the map does not contain the specified key. It must be * 0/{@code false}/{@code null} by default. * * @param rv the new default return value. * @see #defaultReturnValue() */ default void defaultReturnValue(VALUE_GENERIC_TYPE rv) { throw new UnsupportedOperationException(); } /** Gets the default return value. * *

This default implementation just return the default null value * of the type ({@code null} for objects, 0 for scalars, false for Booleans). * * @return the current default return value. */ default VALUE_GENERIC_TYPE defaultReturnValue() { return VALUE_NULL; } }





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