| // 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 static com.google.devtools.build.lib.syntax.compiler.ByteCodeUtils.append; |
| |
| import com.google.devtools.build.lib.syntax.SkylarkList.MutableList; |
| import com.google.devtools.build.lib.syntax.compiler.ByteCodeMethodCalls; |
| import com.google.devtools.build.lib.syntax.compiler.ByteCodeUtils; |
| import com.google.devtools.build.lib.syntax.compiler.DebugInfo; |
| import com.google.devtools.build.lib.syntax.compiler.DebugInfo.AstAccessors; |
| import com.google.devtools.build.lib.syntax.compiler.NewObject; |
| import com.google.devtools.build.lib.syntax.compiler.Variable.InternalVariable; |
| import com.google.devtools.build.lib.syntax.compiler.VariableScope; |
| |
| import net.bytebuddy.implementation.bytecode.ByteCodeAppender; |
| import net.bytebuddy.implementation.bytecode.Removal; |
| |
| 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(Expression outputExpression) { |
| super('[', ']', outputExpression); |
| this.outputExpression = outputExpression; |
| } |
| |
| @Override |
| String printExpressions() { |
| return outputExpression.toString(); |
| } |
| |
| @Override |
| OutputCollector createCollector(Environment env) { |
| return new ListOutputCollector(); |
| } |
| |
| @Override |
| InternalVariable compileInitialization(VariableScope scope, List<ByteCodeAppender> code) { |
| InternalVariable list = scope.freshVariable(ArrayList.class); |
| append(code, NewObject.fromConstructor(ArrayList.class).arguments()); |
| code.add(list.store()); |
| return list; |
| } |
| |
| @Override |
| ByteCodeAppender compileCollector( |
| VariableScope scope, |
| InternalVariable collection, |
| DebugInfo debugInfo, |
| AstAccessors debugAccessors) |
| throws EvalException { |
| List<ByteCodeAppender> code = new ArrayList<>(); |
| append(code, collection.load()); |
| code.add(outputExpression.compile(scope, debugInfo)); |
| append(code, ByteCodeMethodCalls.BCList.add, Removal.SINGLE); |
| return ByteCodeUtils.compoundAppender(code); |
| } |
| |
| @Override |
| ByteCodeAppender compileBuilding(VariableScope scope, InternalVariable collection) { |
| return new ByteCodeAppender.Simple( |
| NewObject.fromConstructor(MutableList.class, Iterable.class, Environment.class) |
| .arguments(collection.load(), scope.loadEnvironment())); |
| } |
| |
| /** |
| * 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 void evaluateAndCollect(Environment env) throws EvalException, InterruptedException { |
| result.add(outputExpression.eval(env)); |
| } |
| |
| @Override |
| public Object getResult(Environment env) throws EvalException { |
| return new MutableList(result, env); |
| } |
| } |
| } |