73 lines
2.3 KiB
Java
73 lines
2.3 KiB
Java
/*
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* Copyright (C) 2017 The Dagger Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dagger.internal;
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import static dagger.internal.Preconditions.checkNotNull;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Set;
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/**
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* A fluent builder class that returns a {@link Set}. Used in component implementations where a set
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* must be created in one fluent statement for inlined request fulfillments.
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*/
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public final class SetBuilder<T> {
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private static final String SET_CONTRIBUTIONS_CANNOT_BE_NULL =
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"Set contributions cannot be null";
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private final List<T> contributions;
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private SetBuilder(int estimatedSize) {
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contributions = new ArrayList<>(estimatedSize);
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}
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/**
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* {@code estimatedSize} is the number of bindings which contribute to the set. They may each
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* provide {@code [0..n)} instances to the set. Because the final size is unknown, {@code
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* contributions} are collected in a list and only hashed in {@link #build()}.
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*/
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public static <T> SetBuilder<T> newSetBuilder(int estimatedSize) {
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return new SetBuilder<T>(estimatedSize);
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}
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public SetBuilder<T> add(T t) {
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contributions.add(checkNotNull(t, SET_CONTRIBUTIONS_CANNOT_BE_NULL));
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return this;
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}
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public SetBuilder<T> addAll(Collection<? extends T> collection) {
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for (T item : collection) {
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checkNotNull(item, SET_CONTRIBUTIONS_CANNOT_BE_NULL);
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}
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contributions.addAll(collection);
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return this;
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}
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public Set<T> build() {
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if (contributions.isEmpty()) {
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return Collections.emptySet();
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} else if (contributions.size() == 1) {
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return Collections.singleton(contributions.get(0));
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} else {
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return Collections.unmodifiableSet(new HashSet<>(contributions));
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}
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}
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}
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