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/*
* Copyright (C) 2017 The Dagger 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 dagger.internal;
import static dagger.internal.Preconditions.checkNotNull;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* A fluent builder class that returns a {@link Set}. Used in component implementations where a set
* must be created in one fluent statement for inlined request fulfillments.
*/
public final class SetBuilder<T> {
private static final String SET_CONTRIBUTIONS_CANNOT_BE_NULL =
"Set contributions cannot be null";
private final List<T> contributions;
private SetBuilder(int estimatedSize) {
contributions = new ArrayList<>(estimatedSize);
}
/**
* {@code estimatedSize} is the number of bindings which contribute to the set. They may each
* provide {@code [0..n)} instances to the set. Because the final size is unknown, {@code
* contributions} are collected in a list and only hashed in {@link #build()}.
*/
public static <T> SetBuilder<T> newSetBuilder(int estimatedSize) {
return new SetBuilder<T>(estimatedSize);
}
public SetBuilder<T> add(T t) {
contributions.add(checkNotNull(t, SET_CONTRIBUTIONS_CANNOT_BE_NULL));
return this;
}
public SetBuilder<T> addAll(Collection<? extends T> collection) {
for (T item : collection) {
checkNotNull(item, SET_CONTRIBUTIONS_CANNOT_BE_NULL);
}
contributions.addAll(collection);
return this;
}
public Set<T> build() {
switch (contributions.size()) {
case 0:
return Collections.emptySet();
case 1:
return Collections.singleton(contributions.get(0));
default:
return Collections.unmodifiableSet(new HashSet<>(contributions));
}
}
}