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/*
* Copyright (C) 2008 The Guava Authors
*
* 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 com.google.common.collect;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.J2ktIncompatible;
import java.util.Arrays;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* Methods factored out so that they can be emulated differently in GWT.
*
* @author Hayward Chan
*/
@GwtCompatible(emulated = true)
@ElementTypesAreNonnullByDefault
final class Platform {
private static final java.util.logging.Logger logger =
java.util.logging.Logger.getLogger(Platform.class.getName());
/** Returns the platform preferred implementation of a map based on a hash table. */
static <K extends @Nullable Object, V extends @Nullable Object>
Map<K, V> newHashMapWithExpectedSize(int expectedSize) {
return Maps.newHashMapWithExpectedSize(expectedSize);
}
/**
* Returns the platform preferred implementation of an insertion ordered map based on a hash
* table.
*/
static <K extends @Nullable Object, V extends @Nullable Object>
Map<K, V> newLinkedHashMapWithExpectedSize(int expectedSize) {
return Maps.newLinkedHashMapWithExpectedSize(expectedSize);
}
/** Returns the platform preferred implementation of a set based on a hash table. */
static <E extends @Nullable Object> Set<E> newHashSetWithExpectedSize(int expectedSize) {
return Sets.newHashSetWithExpectedSize(expectedSize);
}
/** Returns the platform preferred implementation of a thread-safe hash set. */
static <E> Set<E> newConcurrentHashSet() {
return ConcurrentHashMap.newKeySet();
}
/**
* Returns the platform preferred implementation of an insertion ordered set based on a hash
* table.
*/
static <E extends @Nullable Object> Set<E> newLinkedHashSetWithExpectedSize(int expectedSize) {
return Sets.newLinkedHashSetWithExpectedSize(expectedSize);
}
/**
* Returns the platform preferred map implementation that preserves insertion order when used only
* for insertions.
*/
static <K extends @Nullable Object, V extends @Nullable Object>
Map<K, V> preservesInsertionOrderOnPutsMap() {
return Maps.newLinkedHashMap();
}
/**
* Returns the platform preferred set implementation that preserves insertion order when used only
* for insertions.
*/
static <E extends @Nullable Object> Set<E> preservesInsertionOrderOnAddsSet() {
return Sets.newLinkedHashSet();
}
/**
* Returns a new array of the given length with the same type as a reference array.
*
* @param reference any array of the desired type
* @param length the length of the new array
*/
/*
* The new array contains nulls, even if the old array did not. If we wanted to be accurate, we
* would declare a return type of `@Nullable T[]`. However, we've decided not to think too hard
* about arrays for now, as they're a mess. (We previously discussed this in the review of
* ObjectArrays, which is the main caller of this method.)
*/
static <T extends @Nullable Object> T[] newArray(T[] reference, int length) {
T[] empty = reference.length == 0 ? reference : Arrays.copyOf(reference, 0);
return Arrays.copyOf(empty, length);
}
/** Equivalent to Arrays.copyOfRange(source, from, to, arrayOfType.getClass()). */
/*
* Arrays are a mess from a nullness perspective, and Class instances for object-array types are
* even worse. For now, we just suppress and move on with our lives.
*
* - https://github.com/jspecify/jspecify/issues/65
*
* - https://github.com/jspecify/jdk/commit/71d826792b8c7ef95d492c50a274deab938f2552
*/
@SuppressWarnings("nullness")
static <T extends @Nullable Object> T[] copy(Object[] source, int from, int to, T[] arrayOfType) {
return Arrays.copyOfRange(source, from, to, (Class<? extends T[]>) arrayOfType.getClass());
}
/**
* Configures the given map maker to use weak keys, if possible; does nothing otherwise (i.e., in
* GWT). This is sometimes acceptable, when only server-side code could generate enough volume
* that reclamation becomes important.
*/
@J2ktIncompatible
static MapMaker tryWeakKeys(MapMaker mapMaker) {
return mapMaker.weakKeys();
}
static <E extends Enum<E>> Class<E> getDeclaringClassOrObjectForJ2cl(E e) {
return e.getDeclaringClass();
}
static int reduceIterationsIfGwt(int iterations) {
return iterations;
}
static int reduceExponentIfGwt(int exponent) {
return exponent;
}
private Platform() {}
}
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