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// 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.Optional;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.syntax.compiler.DebugInfo;
import com.google.devtools.build.lib.syntax.compiler.LoopLabels;
import com.google.devtools.build.lib.syntax.compiler.VariableScope;
import net.bytebuddy.implementation.bytecode.ByteCodeAppender;
import net.bytebuddy.implementation.bytecode.member.MethodReturn;
/**
* A wrapper Statement class for return expressions.
*/
public class ReturnStatement extends Statement {
/**
* Exception sent by the return statement, to be caught by the function body.
*/
public class ReturnException extends EvalException {
Object value;
public ReturnException(Location location, Object value) {
super(location, "Return statements must be inside a function");
this.value = value;
}
public Object getValue() {
return value;
}
@Override
public boolean canBeAddedToStackTrace() {
return false;
}
}
private final Expression returnExpression;
public ReturnStatement(Expression returnExpression) {
this.returnExpression = returnExpression;
}
@Override
void doExec(Environment env) throws EvalException, InterruptedException {
throw new ReturnException(returnExpression.getLocation(), returnExpression.eval(env));
}
Expression getReturnExpression() {
return returnExpression;
}
@Override
public String toString() {
return "return " + returnExpression;
}
@Override
public void accept(SyntaxTreeVisitor visitor) {
visitor.visit(this);
}
@Override
void validate(ValidationEnvironment env) throws EvalException {
if (env.isTopLevel()) {
throw new EvalException(getLocation(), "Return statements must be inside a function");
}
returnExpression.validate(env);
}
@Override
ByteCodeAppender compile(
VariableScope scope, Optional<LoopLabels> loopLabels, DebugInfo debugInfo)
throws EvalException {
ByteCodeAppender compiledExpression = returnExpression.compile(scope, debugInfo);
return new ByteCodeAppender.Compound(
compiledExpression, new ByteCodeAppender.Simple(MethodReturn.REFERENCE));
}
}
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