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

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Here is the source code for com.facebook.buck.query.AbstractSetExpression.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.core.util.immutables.BuckStyleTuple;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import org.immutables.value.Value;

/**
 * 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>
 * % buck query 'allpaths(foo, bar)' | grep ... | sed ... | awk ... >file
 * % buck 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>
 */
@Value.Immutable(prehash = true)
@BuckStyleTuple
abstract class AbstractSetExpression extends QueryExpression {
    abstract ImmutableList<TargetLiteral> getWords();

    @Override
    ImmutableSet<QueryTarget> eval(QueryEvaluator evaluator, QueryEnvironment env) throws QueryException {
        ImmutableSet.Builder<QueryTarget> result = new ImmutableSet.Builder<>();
        for (TargetLiteral expr : getWords()) {
            result.addAll(evaluator.eval(expr, env));
        }
        return result.build();
    }

    @Override
    public void traverse(QueryExpression.Visitor visitor) {
        if (visitor.visit(this) == VisitResult.CONTINUE) {
            for (TargetLiteral word : getWords()) {
                word.traverse(visitor);
            }
        }
    }

    @Override
    public String toString() {
        return "set(" + Joiner.on(' ').join(getWords()) + ")";
    }
}