| // 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.base.Joiner; |
| import com.google.devtools.build.lib.query2.engine.QueryEnvironment.QueryTaskFuture; |
| import java.util.ArrayList; |
| import java.util.Collection; |
| import java.util.List; |
| |
| /** |
| * 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> |
| */ |
| public class SetExpression extends QueryExpression { |
| |
| private final List<TargetLiteral> words; |
| |
| public SetExpression(List<TargetLiteral> words) { |
| this.words = words; |
| } |
| |
| @Override |
| public <T> QueryTaskFuture<Void> eval( |
| QueryEnvironment<T> env, QueryExpressionContext<T> context, Callback<T> callback) { |
| ArrayList<QueryTaskFuture<Void>> queryTasks = new ArrayList<>(words.size()); |
| for (TargetLiteral expr : words) { |
| queryTasks.add(env.eval(expr, context, callback)); |
| } |
| return env.whenAllSucceed(queryTasks); |
| } |
| |
| @Override |
| public void collectTargetPatterns(Collection<String> literals) { |
| for (TargetLiteral expr : words) { |
| expr.collectTargetPatterns(literals); |
| } |
| } |
| |
| @Override |
| public <T, C> T accept(QueryExpressionVisitor<T, C> visitor, C context) { |
| return visitor.visit(this, context); |
| } |
| |
| /** Gets the list of {@link TargetLiteral}s contained in the expression. */ |
| public List<TargetLiteral> getWords() { |
| return words; |
| } |
| |
| @Override |
| public String toString() { |
| return "set(" + Joiner.on(' ').join(words) + ")"; |
| } |
| } |