com.google.devtools.build.lib.query2.engine.SomeFunction.java Source code

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Here is the source code for com.google.devtools.build.lib.query2.engine.SomeFunction.java

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// Copyright 2014 The Bazel Authors. 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.google.devtools.build.lib.query2.engine;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.Argument;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.ArgumentType;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryFunction;
import java.util.List;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * A some(x) filter expression, which returns an arbitrary node in set x, or
 * fails if x is empty.
 *
 * <pre>expr ::= SOME '(' expr ')'</pre>
 */
class SomeFunction implements QueryFunction {
    SomeFunction() {
    }

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

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

    @Override
    public List<ArgumentType> getArgumentTypes() {
        return ImmutableList.of(ArgumentType.EXPRESSION);
    }

    @Override
    public <T> void eval(QueryEnvironment<T> env, VariableContext<T> context, QueryExpression expression,
            List<Argument> args, final Callback<T> callback) throws QueryException, InterruptedException {
        final AtomicBoolean someFound = new AtomicBoolean(false);
        env.eval(args.get(0).getExpression(), context, new Callback<T>() {
            @Override
            public void process(Iterable<T> partialResult) throws QueryException, InterruptedException {
                if (someFound.get() || Iterables.isEmpty(partialResult)) {
                    return;
                }
                callback.process(ImmutableSet.of(partialResult.iterator().next()));
                someFound.set(true);
            }
        });
        if (!someFound.get()) {
            throw new QueryException(expression, "argument set is empty");
        }
    }

    @Override
    public <T> void parEval(QueryEnvironment<T> env, VariableContext<T> context, QueryExpression expression,
            List<Argument> args, ThreadSafeCallback<T> callback, ForkJoinPool forkJoinPool)
            throws QueryException, InterruptedException {
        eval(env, context, expression, args, callback);
    }
}