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/*
* Copyright (C) 2002-2022 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 it.unimi.dsi.fastutil.objects;
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
public interface Object2ReferenceFunction extends Function {
/**
* 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 V put(final K key, final V 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)
*/
V get(Object key);
/**
* Returns the value associated by this function to the specified key, or give the specified value
* if not present.
*
* @param key the key.
* @param defaultValue the value to return if not present.
* @return the corresponding value, or {@code defaultValue} if no value was present for the given
* key.
* @see Function#getOrDefault(Object, Object)
* @since 8.5.0
*/
default V getOrDefault(final Object key, final V defaultValue) {
final V v;
return ((v = get(key)) != defaultReturnValue() || containsKey(key)) ? v : defaultValue;
}
/**
* 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 V remove(final Object key) {
throw new UnsupportedOperationException();
}
/**
* 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(V 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 V defaultReturnValue() {
return (null);
}
default it.unimi.dsi.fastutil.objects.Object2ByteFunction andThenByte(it.unimi.dsi.fastutil.objects.Reference2ByteFunction after) {
return k -> after.getByte(get(k));
}
default it.unimi.dsi.fastutil.bytes.Byte2ReferenceFunction composeByte(it.unimi.dsi.fastutil.bytes.Byte2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2ShortFunction andThenShort(it.unimi.dsi.fastutil.objects.Reference2ShortFunction after) {
return k -> after.getShort(get(k));
}
default it.unimi.dsi.fastutil.shorts.Short2ReferenceFunction composeShort(it.unimi.dsi.fastutil.shorts.Short2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2IntFunction andThenInt(it.unimi.dsi.fastutil.objects.Reference2IntFunction after) {
return k -> after.getInt(get(k));
}
default it.unimi.dsi.fastutil.ints.Int2ReferenceFunction composeInt(it.unimi.dsi.fastutil.ints.Int2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2LongFunction andThenLong(it.unimi.dsi.fastutil.objects.Reference2LongFunction after) {
return k -> after.getLong(get(k));
}
default it.unimi.dsi.fastutil.longs.Long2ReferenceFunction composeLong(it.unimi.dsi.fastutil.longs.Long2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2CharFunction andThenChar(it.unimi.dsi.fastutil.objects.Reference2CharFunction after) {
return k -> after.getChar(get(k));
}
default it.unimi.dsi.fastutil.chars.Char2ReferenceFunction composeChar(it.unimi.dsi.fastutil.chars.Char2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2FloatFunction andThenFloat(it.unimi.dsi.fastutil.objects.Reference2FloatFunction after) {
return k -> after.getFloat(get(k));
}
default it.unimi.dsi.fastutil.floats.Float2ReferenceFunction composeFloat(it.unimi.dsi.fastutil.floats.Float2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2DoubleFunction andThenDouble(it.unimi.dsi.fastutil.objects.Reference2DoubleFunction after) {
return k -> after.getDouble(get(k));
}
default it.unimi.dsi.fastutil.doubles.Double2ReferenceFunction composeDouble(it.unimi.dsi.fastutil.doubles.Double2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2ObjectFunction andThenObject(it.unimi.dsi.fastutil.objects.Reference2ObjectFunction after) {
return k -> after.get(get(k));
}
default it.unimi.dsi.fastutil.objects.Object2ReferenceFunction composeObject(it.unimi.dsi.fastutil.objects.Object2ObjectFunction before) {
return k -> get(before.get(k));
}
default it.unimi.dsi.fastutil.objects.Object2ReferenceFunction andThenReference(it.unimi.dsi.fastutil.objects.Reference2ReferenceFunction after) {
return k -> after.get(get(k));
}
default it.unimi.dsi.fastutil.objects.Reference2ReferenceFunction composeReference(it.unimi.dsi.fastutil.objects.Reference2ObjectFunction before) {
return k -> get(before.get(k));
}
}