| // 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.syntax; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.devtools.build.lib.events.Location; |
| import com.google.devtools.build.lib.syntax.SkylarkList.MutableList; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.List; |
| |
| /** Syntax node for lists comprehension expressions. */ |
| public final class ListComprehension extends AbstractComprehension { |
| private final Expression outputExpression; |
| |
| public ListComprehension(List<Clause> clauses, Expression outputExpression) { |
| super(clauses, outputExpression); |
| this.outputExpression = outputExpression; |
| } |
| |
| @Override |
| protected char openingBracket() { |
| return '['; |
| } |
| |
| @Override |
| protected char closingBracket() { |
| return ']'; |
| } |
| |
| public Expression getOutputExpression() { |
| return outputExpression; |
| } |
| |
| @Override |
| protected void printExpressions(Appendable buffer) throws IOException { |
| outputExpression.prettyPrint(buffer); |
| } |
| |
| /** Builder for {@link ListComprehension}. */ |
| public static class Builder extends AbstractBuilder { |
| |
| private Expression outputExpression; |
| |
| public Builder setOutputExpression(Expression outputExpression) { |
| this.outputExpression = outputExpression; |
| return this; |
| } |
| |
| @Override |
| public ListComprehension build() { |
| Preconditions.checkState(!clauses.isEmpty()); |
| return new ListComprehension(clauses, Preconditions.checkNotNull(outputExpression)); |
| } |
| } |
| |
| @Override |
| OutputCollector createCollector(Environment env) { |
| return new ListOutputCollector(); |
| } |
| |
| /** |
| * Helper class that collects the intermediate results of the {@code ListComprehension} and |
| * provides access to the resulting {@code List}. |
| */ |
| private final class ListOutputCollector implements OutputCollector { |
| private final List<Object> result; |
| |
| ListOutputCollector() { |
| result = new ArrayList<>(); |
| } |
| |
| @Override |
| public Location getLocation() { |
| return ListComprehension.this.getLocation(); |
| } |
| |
| @Override |
| public List<Clause> getClauses() { |
| return ListComprehension.this.getClauses(); |
| } |
| |
| @Override |
| public void evaluateAndCollect(Environment env) throws EvalException, InterruptedException { |
| result.add(outputExpression.eval(env)); |
| } |
| |
| @Override |
| public Object getResult(Environment env) throws EvalException { |
| return MutableList.copyOf(env, result); |
| } |
| } |
| } |