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// 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.google.devtools.build.lib.query2.engine;
import com.google.common.base.Joiner;
import java.util.Collection;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
/**
* A set(word, ..., word) expression, which computes the union of zero or more
* target patterns separated by whitespace. This is intended to support the
* use-case in which a set of labels written to a file by a previous query
* expression can be modified externally, then used as input to another query,
* like so:
*
* <pre>
* % blaze query 'somepath(foo, bar)' | grep ... | sed ... | awk ... >file
* % blaze query "kind(qux_library, set($(<file)))"
* </pre>
*
* <p>The grammar currently restricts the operands of set() to being zero or
* more words (target patterns), with no intervening punctuation. In principle
* this could be extended to arbitrary expressions without grammatical
* ambiguity, but this seems excessively general for now.
*
* <pre>expr ::= SET '(' WORD * ')'</pre>
*/
class SetExpression extends QueryExpression {
private final List<TargetLiteral> words;
SetExpression(List<TargetLiteral> words) {
this.words = words;
}
@Override
public <T> Set<T> eval(QueryEnvironment<T> env) throws QueryException {
Set<T> result = new LinkedHashSet<>();
for (TargetLiteral expr : words) {
result.addAll(expr.eval(env));
}
return result;
}
@Override
public void collectTargetPatterns(Collection<String> literals) {
for (TargetLiteral expr : words) {
expr.collectTargetPatterns(literals);
}
}
@Override
public String toString() {
return "set(" + Joiner.on(' ').join(words) + ")";
}
}
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