com.facebook.buck.graph.DirectedAcyclicGraph.java Source code

Introduction

Here is the source code for com.facebook.buck.graph.DirectedAcyclicGraph.java

Source

/*
 * Copyright 2015-present Facebook, 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.facebook.buck.graph;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import com.google.common.collect.Sets;

import java.util.Objects;

public class DirectedAcyclicGraph<T> implements TraversableGraph<T> {

    private final ImmutableSet<T> nodes;
    private final ImmutableSetMultimap<T, T> outgoingEdges;
    private final ImmutableSetMultimap<T, T> incomingEdges;

    public DirectedAcyclicGraph(MutableDirectedGraph<T> graph) {
        Preconditions.checkState(graph.isAcyclic(), "Graph must by acyclic");
        this.nodes = graph.createImmutableCopyOfNodes();
        this.outgoingEdges = graph.createImmutableCopyOfOutgoingEdges();
        this.incomingEdges = graph.createImmutableCopyOfIncomingEdges();
    }

    @Override
    public ImmutableSet<T> getOutgoingNodesFor(T source) {
        return outgoingEdges.get(source);
    }

    @Override
    public ImmutableSet<T> getIncomingNodesFor(T sink) {
        return incomingEdges.get(sink);
    }

    @Override
    public ImmutableSet<T> getNodesWithNoOutgoingEdges() {
        return ImmutableSet.copyOf(Sets.difference(nodes, outgoingEdges.keySet()));
    }

    @Override
    public ImmutableSet<T> getNodesWithNoIncomingEdges() {
        return ImmutableSet.copyOf(Sets.difference(nodes, incomingEdges.keySet()));
    }

    @Override
    public ImmutableSet<T> getNodes() {
        return nodes;
    }

    @Override
    public boolean equals(Object other) {
        if (!(other instanceof DirectedAcyclicGraph)) {
            return false;
        }

        DirectedAcyclicGraph<?> that = (DirectedAcyclicGraph<?>) other;
        return Objects.equals(this.nodes, that.nodes) && Objects.equals(this.outgoingEdges, that.outgoingEdges)
                && Objects.equals(this.incomingEdges, that.incomingEdges);
    }

    @Override
    public int hashCode() {
        return Objects.hash(nodes, outgoingEdges, incomingEdges);
    }
}