com.couchbase.client.core.util.CbCollections Maven / Gradle / Ivy
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/*
* Copyright 2019 Couchbase, Inc.
*
* 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.couchbase.client.core.util;
import com.couchbase.client.core.annotation.Stability;
import com.couchbase.client.core.error.InvalidArgumentException;
import reactor.util.annotation.Nullable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Predicate;
import static java.util.Collections.emptyList;
import static java.util.Collections.emptyMap;
import static java.util.Collections.emptySet;
import static java.util.Collections.unmodifiableList;
import static java.util.Collections.unmodifiableMap;
import static java.util.Collections.unmodifiableSet;
import static java.util.Objects.requireNonNull;
import static java.util.stream.Collectors.toList;
import static java.util.stream.Collectors.toMap;
@Stability.Internal
public class CbCollections {
private CbCollections() {
throw new AssertionError("not instantiable");
}
/**
* Backport of {@code List.copyOf}.
*
* Returns an unmodifiable list containing all elements of the given collection.
* Subsequent changes to the original collection are not reflected in the returned list.
*
* @throws NullPointerException if original is null or contains any nulls
*/
@SuppressWarnings("unchecked")
public static List listCopyOf(Collection original) {
return (List) listOf(original.toArray());
}
/**
* Backport of {@code Set.copyOf}.
*
* Returns an unmodifiable set containing all elements of the given collection.
* If the original contains duplicate items, an arbitrary element is preserved.
* Subsequent changes to the original collection are not reflected in the returned set.
*
* @throws NullPointerException if original is null or contains any nulls
*/
@SuppressWarnings("unchecked")
public static Set setCopyOf(Collection original) {
return (Set) setOf(new HashSet<>(original).toArray());
}
/**
* Backport of {@code Map.copyOf}.
*
* Returns an unmodifiable map containing all entries of the given map.
* Subsequent changes to the original map are not reflected in the returned map.
*
* @throws NullPointerException if original is null or contains any null keys or values.
*/
public static Map mapCopyOf(Map original) {
Map result = new HashMap<>();
original.forEach((k,v) -> putUniqueKey(result, k, v));
return unmodifiableMap(result);
}
/**
* Returns a new unmodifiable list with the same contents as the given collection.
* Subsequent changes to the original collection are not reflected in the returned list.
*
* @param c may be {@code null}, in which case an empty list is returned.
*/
public static List copyToUnmodifiableList(@Nullable Collection c) {
return isNullOrEmpty(c) ? emptyList() : unmodifiableList(new ArrayList<>(c));
}
/**
* Returns a new unmodifiable set with the same contents as the given collection.
* Subsequent changes to the original collection are not reflected in the returned set.
*
* @param c may be {@code null}, in which case an empty set is returned.
*/
public static Set copyToUnmodifiableSet(@Nullable Collection c) {
return isNullOrEmpty(c) ? emptySet() : unmodifiableSet(new HashSet<>(c));
}
public static boolean isNullOrEmpty(@Nullable Collection c) {
return c == null || c.isEmpty();
}
public static boolean isNullOrEmpty(@Nullable Map m) {
return m == null || m.isEmpty();
}
public static boolean isNullOrEmpty(@Nullable String s) {
return s == null || s.isEmpty();
}
/**
* Returns an unmodifiable set containing the given items.
*
* @throws NullPointerException if any item is null
* @throws InvalidArgumentException if there are duplicate items
*/
@SafeVarargs
public static Set setOf(T... items) {
Set result = new HashSet<>();
for (T item : items) {
if (!result.add(requireNonNull(item, "Set may not contain null"))) {
throw InvalidArgumentException.fromMessage("Duplicate item: " + item);
}
}
return unmodifiableSet(result);
}
/**
* Returns an unmodifiable list containing the given items.
*
* @throws NullPointerException if any item is null
*/
@SafeVarargs
public static List listOf(T... items) {
List result = new ArrayList<>(items.length);
for (T item : items) {
result.add(requireNonNull(item, "List may not contain null"));
}
return unmodifiableList(result);
}
/**
* Returns an unmodifiable empty map.
*/
public static Map mapOf() {
return emptyMap();
}
/**
* Returns an unmodifiable map containing the given key/value pairs.
*
* @throws NullPointerException if any key or value is null
* @throws InvalidArgumentException if there are duplicate keys
*/
public static Map mapOf(K key1, V value1) {
Map result = new HashMap<>();
putUniqueKey(result, key1, value1);
return unmodifiableMap(result);
}
/**
* Returns an unmodifiable map containing the given key/value pairs.
*
* @throws NullPointerException if any key or value is null
* @throws InvalidArgumentException if there are duplicate keys
*/
public static Map mapOf(K key1, V value1,
K key2, V value2) {
Map result = new HashMap<>();
putUniqueKey(result, key1, value1);
putUniqueKey(result, key2, value2);
return unmodifiableMap(result);
}
/**
* Returns an unmodifiable map containing the given key/value pairs.
*
* @throws NullPointerException if any key or value is null
* @throws InvalidArgumentException if there are duplicate keys
*/
public static Map mapOf(K key1, V value1,
K key2, V value2,
K key3, V value3) {
Map result = new HashMap<>();
putUniqueKey(result, key1, value1);
putUniqueKey(result, key2, value2);
putUniqueKey(result, key3, value3);
return unmodifiableMap(result);
}
/**
* Returns an unmodifiable map containing the given key/value pairs.
*
* @throws NullPointerException if any key or value is null
* @throws InvalidArgumentException if there are duplicate keys
*/
@SuppressWarnings("Duplicates")
public static Map mapOf(K key1, V value1,
K key2, V value2,
K key3, V value3,
K key4, V value4) {
Map result = new HashMap<>();
putUniqueKey(result, key1, value1);
putUniqueKey(result, key2, value2);
putUniqueKey(result, key3, value3);
putUniqueKey(result, key4, value4);
return unmodifiableMap(result);
}
/**
* Returns an unmodifiable map containing the given key/value pairs.
*
* @throws NullPointerException if any key or value is null
* @throws InvalidArgumentException if there are duplicate keys
*/
@SuppressWarnings("Duplicates")
public static Map mapOf(K key1, V value1,
K key2, V value2,
K key3, V value3,
K key4, V value4,
K key5, V value5) {
Map result = new HashMap<>();
putUniqueKey(result, key1, value1);
putUniqueKey(result, key2, value2);
putUniqueKey(result, key3, value3);
putUniqueKey(result, key4, value4);
putUniqueKey(result, key5, value5);
return unmodifiableMap(result);
}
private static void putUniqueKey(Map map, K key, V value) {
requireNonNull(key, "Key may not be null.");
requireNonNull(value, "Value may not be null.");
if (map.put(key, value) != null) {
throw InvalidArgumentException.fromMessage("Duplicate key: " + key);
}
}
/**
* Convenience method equivalent to:
*
* input.stream().map(transformer).collect(toList())
*
*/
public static List transform(Iterable input, Function transformer) {
List result = new ArrayList<>();
input.forEach(it -> result.add(transformer.apply(it)));
return result;
}
/**
* Convenience method equivalent to:
*
* input.stream().map(transformer).collect(toList())
*
*/
public static List transform(Iterator input, Function transformer) {
List result = new ArrayList<>();
input.forEachRemaining(it -> result.add(transformer.apply(it)));
return result;
}
/**
* Convenience method equivalent to:
*
* Arrays.stream(input).map(transformer).collect(toList())
*
*/
public static List transform(T1[] input, Function transformer) {
return Arrays.stream(input)
.map(transformer)
.collect(toList());
}
/**
* Convenience method equivalent to:
*
* input.stream().filter(predicate).collect(toList())
*
*/
public static List filter(Iterable input, Predicate predicate) {
List result = new ArrayList<>();
input.forEach(it -> {
if (predicate.test(it)) {
result.add(it);
}
});
return result;
}
/**
* Convenience method equivalent to:
*
* Arrays.stream(input).filter(predicate).collect(toList())
*
*/
public static List filter(T[] input, Predicate predicate) {
return Arrays.stream(input)
.filter(predicate)
.collect(toList());
}
public static Map transformValues(Map map, Function transformer) {
return map.entrySet()
.stream()
.collect(toMap(Map.Entry::getKey, entry -> transformer.apply(entry.getValue())));
}
public static Map transformValues(Map map, BiFunction transformer) {
return map.entrySet()
.stream()
.collect(toMap(Map.Entry::getKey, entry -> transformer.apply(entry.getKey(), entry.getValue())));
}
/**
* Returns an unmodifiable list containing all elements of the given iterable.
* Subsequent changes to the original iterable are not reflected in the returned list.
*
* @throws NullPointerException if original is null or contains any nulls
*/
public static List listCopyOf(Iterable original) {
List result = new ArrayList<>();
original.forEach(it -> result.add(requireNonNull(it, "List may not contain null.")));
return unmodifiableList(result);
}
}