/*
 * Copyright (C) 2016 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.graph;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterators;
import com.google.common.collect.UnmodifiableIterator;
import java.util.AbstractSet;
import java.util.Map;
import org.checkerframework.checker.nullness.qual.Nullable;

A class to represent the set of edges connecting an (implicit) origin node to a target node.

The EdgesConnecting<E>.nodeToOutEdge map means this class only works on networks without parallel edges. See MultiEdgesConnecting for a class that works with parallel edges.

Author:James Sexton
Type parameters:
  • <E> – Edge parameter type
/** * A class to represent the set of edges connecting an (implicit) origin node to a target node. * * <p>The {@link #nodeToOutEdge} map means this class only works on networks without parallel edges. * See {@link MultiEdgesConnecting} for a class that works with parallel edges. * * @author James Sexton * @param <E> Edge parameter type */
final class EdgesConnecting<E> extends AbstractSet<E> { private final Map<?, E> nodeToOutEdge; private final Object targetNode; EdgesConnecting(Map<?, E> nodeToEdgeMap, Object targetNode) { this.nodeToOutEdge = checkNotNull(nodeToEdgeMap); this.targetNode = checkNotNull(targetNode); } @Override public UnmodifiableIterator<E> iterator() { E connectingEdge = getConnectingEdge(); return (connectingEdge == null) ? ImmutableSet.<E>of().iterator() : Iterators.singletonIterator(connectingEdge); } @Override public int size() { return getConnectingEdge() == null ? 0 : 1; } @Override public boolean contains(@Nullable Object edge) { E connectingEdge = getConnectingEdge(); return (connectingEdge != null && connectingEdge.equals(edge)); } private @Nullable E getConnectingEdge() { return nodeToOutEdge.get(targetNode); } }