com.facebook.buck.rules.AbstractDependencyVisitor.java Source code

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Here is the source code for com.facebook.buck.rules.AbstractDependencyVisitor.java

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/*
 * Copyright 2012-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.rules;

import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;

import java.util.Collection;
import java.util.Queue;
import java.util.Set;

/**
 * Performs a breadth-first traversal of a {@link BuildRule}'s dependencies.
 */
public abstract class AbstractDependencyVisitor {

    private final Queue<BuildRule> toExplore;
    private final Set<BuildRule> explored;

    public AbstractDependencyVisitor(BuildRule initialRule) {
        this(initialRule, false /* excludeRoot */);
    }

    public AbstractDependencyVisitor(BuildRule initialRule, boolean excludeRoot) {
        this(excludeRoot ? initialRule.getDeps() : ImmutableSet.of(initialRule));
    }

    public AbstractDependencyVisitor(Collection<BuildRule> initialDeps) {
        toExplore = Lists.newLinkedList();
        toExplore.addAll(initialDeps);
        explored = Sets.newHashSet();
    }

    public final void start() {
        while (!toExplore.isEmpty()) {
            BuildRule currentRule = toExplore.remove();
            if (explored.contains(currentRule)) {
                continue;
            }

            ImmutableSet<BuildRule> depsToVisit = visit(currentRule);
            explored.add(currentRule);

            for (BuildRule dep : depsToVisit) {
                if (!explored.contains(dep)) {
                    toExplore.add(dep);
                }
            }
        }

        onComplete();
    }

    /** Override this method with any logic that should be run when {@link #start()} completes. */
    protected void onComplete() {

    }

    /**
     * To perform a full traversal of the {@code rule}'s transitive dependencies, this rule
     * should return {@code rule.getDeps()}.
     *
     * @param rule Visited build rule
     * @return The set of children to visit after visiting this node.  This set must be a subset of
     *    {@code rule.getDeps()}
     */
    public abstract ImmutableSet<BuildRule> visit(BuildRule rule);

    public static ImmutableSet<BuildRule> maybeVisitAllDeps(BuildRule rule, boolean visitDeps) {
        return visitDeps ? rule.getDeps() : ImmutableSet.<BuildRule>of();
    }
}