com.facebook.buck.query.RdepsFunction.java Source code

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Here is the source code for com.facebook.buck.query.RdepsFunction.java

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/*
 * 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.
 */

// Copyright 2014 Google Inc. All rights reserved.
//
// 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.query;

import com.facebook.buck.query.QueryEnvironment.Argument;
import com.facebook.buck.query.QueryEnvironment.ArgumentType;
import com.facebook.buck.query.QueryEnvironment.QueryFunction;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.util.concurrent.ListeningExecutorService;

import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.Set;

/**
 * A 'rdeps(u, x, [, depth])' expression, which finds the reverse dependencies of the given
 * argument set 'x' within the transitive closure of the set 'u'.
 * The optional parameter 'depth' specifies the depth of the search. If the argument is absent,
 * the search is unbounded.
 *
 * <pre>expr ::= RDEPS '(' expr ',' expr ')'</pre>
 * <pre>       | RDEPS '(' expr ',' expr ',' WORD ')'</pre>
 */
public class RdepsFunction implements QueryFunction {

    private static final ImmutableList<ArgumentType> ARGUMENT_TYPES = ImmutableList.of(ArgumentType.EXPRESSION,
            ArgumentType.EXPRESSION, ArgumentType.INTEGER);

    public RdepsFunction() {
    }

    @Override
    public String getName() {
        return "rdeps";
    }

    @Override
    public int getMandatoryArguments() {
        return 2;
    }

    @Override
    public ImmutableList<ArgumentType> getArgumentTypes() {
        return ARGUMENT_TYPES;
    }

    /**
     * Evaluates to the reverse dependencies of the argument 'x' in the transitive closure of the
     * set 'u'. Breadth first search from the set 'x' until there are no more unvisited nodes in the
     * reverse transitive closure or the maximum depth (if supplied) is reached.
     */
    @Override
    public Set<QueryTarget> eval(QueryEnvironment env, ImmutableList<Argument> args,
            ListeningExecutorService executor) throws QueryException, InterruptedException {
        Set<QueryTarget> universeSet = args.get(0).getExpression().eval(env, executor);
        env.buildTransitiveClosure(universeSet, Integer.MAX_VALUE, executor);
        Predicate<QueryTarget> inUniversePredicate = env.getTransitiveClosure(universeSet)::contains;

        // LinkedHashSet preserves the order of insertion when iterating over the values.
        // The order by which we traverse the result is meaningful because the dependencies are
        // traversed level-by-level.
        Set<QueryTarget> visited = new LinkedHashSet<>();
        Set<QueryTarget> argumentSet = args.get(1).getExpression().eval(env, executor);
        Collection<QueryTarget> current = argumentSet;

        int depthBound = args.size() > 2 ? args.get(2).getInteger() : Integer.MAX_VALUE;
        // Iterating depthBound+1 times because the first one processes the given argument set.
        for (int i = 0; i <= depthBound; i++) {
            // Restrict the search to nodes in the transitive closure of the universe set.
            Iterable<QueryTarget> currentInUniverse = Iterables.filter(current, inUniversePredicate);

            // Filter nodes visited before.
            Collection<QueryTarget> next = env
                    .getReverseDeps(Iterables.filter(currentInUniverse, Predicates.not(visited::contains)));
            Iterables.addAll(visited, currentInUniverse);
            if (next.isEmpty()) {
                break;
            }
            current = next;
        }
        return visited;
    }

}