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

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Here is the source code for com.facebook.buck.query.DepsFunction.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.Predicates;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.util.concurrent.ListeningExecutorService;

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

/**
 * A 'deps(x [, depth])' expression, which finds the dependencies of the given argument set 'x'.
 * The optional parameter 'depth' specifies the depth of the search. If the argument is absent,
 * the search is unbounded.
 *
 * <pre>expr ::= DEPS '(' expr ')'</pre>
 * <pre>       | DEPS '(' expr ',' WORD ')'</pre>
 */
public class DepsFunction implements QueryFunction {

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

    public DepsFunction() {
    }

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

    @Override
    public int getMandatoryArguments() {
        return 1;
    }

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

    /**
     * Evaluates to the dependencies of the argument.
     * Breadth first search from the given argument until there are no more unvisited nodes in the
     * 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> argumentSet = args.get(0).getExpression().eval(env, executor);
        int depthBound = args.size() > 1 ? args.get(1).getInteger() : Integer.MAX_VALUE;
        env.buildTransitiveClosure(argumentSet, depthBound, executor);

        // 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> result = new LinkedHashSet<>();
        Set<QueryTarget> current = argumentSet;

        // Iterating depthBound+1 times because the first one processes the given argument set.
        for (int i = 0; i <= depthBound; i++) {
            Set<QueryTarget> next = env.getFwdDeps(Iterables.filter(current, Predicates.not(result::contains)));
            result.addAll(current);
            if (next.isEmpty()) {
                break;
            }
            current = next;
        }
        return result;
    }

}