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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 com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryTaskCallable;
import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryTaskFuture;
import java.util.List;
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> QueryTaskFuture<Void> eval(
QueryEnvironment<T> env,
QueryExpressionContext<T> context,
final QueryExpression expression,
List<Argument> args,
final Callback<T> callback) {
final AtomicBoolean someFound = new AtomicBoolean(false);
QueryTaskFuture<Void> operandEvalFuture = env.eval(
args.get(0).getExpression(),
context,
new Callback<T>() {
@Override
public void process(Iterable<T> partialResult)
throws QueryException, InterruptedException {
if (Iterables.isEmpty(partialResult) || !someFound.compareAndSet(false, true)) {
return;
}
callback.process(ImmutableSet.of(partialResult.iterator().next()));
}
});
return env.whenSucceedsCall(
operandEvalFuture,
new QueryTaskCallable<Void>() {
@Override
public Void call() throws QueryException {
if (!someFound.get()) {
throw new QueryException(expression, "argument set is empty");
}
return null;
}
});
}
}
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