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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.Sets;
import com.google.common.util.concurrent.ListeningExecutorService;
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.Collection;
import java.util.List;
import java.util.Set;
/**
* A "deps" query expression, which computes the dependencies of the argument. An optional
* integer-literal second argument may be specified; its value bounds the search from the arguments.
*
* <pre>expr ::= DEPS '(' expr ')'</pre>
* <pre> | DEPS '(' expr ',' WORD ')'</pre>
*/
final class DepsFunction implements QueryFunction {
DepsFunction() {
}
@Override
public String getName() {
return "deps";
}
@Override
public int getMandatoryArguments() {
return 1; // last argument is optional
}
@Override
public List<ArgumentType> getArgumentTypes() {
return ImmutableList.of(ArgumentType.EXPRESSION, ArgumentType.INTEGER);
}
/**
* Breadth-first search from the arguments.
*/
@Override
public <T> void eval(
final QueryEnvironment<T> env,
VariableContext<T> context,
final QueryExpression expression,
List<Argument> args,
final Callback<T> callback) throws QueryException, InterruptedException {
final int depthBound = args.size() > 1 ? args.get(1).getInteger() : Integer.MAX_VALUE;
final Uniquifier<T> uniquifier = env.createUniquifier();
env.eval(args.get(0).getExpression(), context, new Callback<T>() {
@Override
public void process(Iterable<T> partialResult) throws QueryException, InterruptedException {
Collection<T> current = Sets.newHashSet(partialResult);
env.buildTransitiveClosure(expression, (Set<T>) current, depthBound);
// We need to iterate depthBound + 1 times.
for (int i = 0; i <= depthBound; i++) {
// Filter already visited nodes: if we see a node in a later round, then we don't need to
// visit it again, because the depth at which we see it at must be greater than or equal
// to the last visit.
ImmutableList<T> toProcess = uniquifier.unique(current);
callback.process(toProcess);
current = ImmutableList.copyOf(env.getFwdDeps(toProcess));
if (current.isEmpty()) {
// Exit when there are no more nodes to visit.
break;
}
}
}
});
}
@Override
public <T> void parEval(
QueryEnvironment<T> env,
VariableContext<T> context,
QueryExpression expression,
List<Argument> args,
ThreadSafeCallback<T> callback,
ListeningExecutorService executorService) throws QueryException, InterruptedException {
eval(env, context, expression, args, callback);
}
}
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