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// Copyright 2023 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.skyframe.state;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyFunction.LookupEnvironment;
import javax.annotation.Nullable;
/**
* A state machine that outputs a value or one of three possible exceptions.
*
* <p>This class serves as a bridge between a {@link StateMachine} and a {@link SkyFunction}.
*
* <p>Subclasses should call {@link #setValue}, {@link #setException1}, {@link #setException2} or
* {@link #setException3} to emit results.
*/
public abstract class ValueOrException3Producer<
V, E1 extends Exception, E2 extends Exception, E3 extends Exception>
implements StateMachine {
private final Driver driver = new Driver(this);
private V value;
private E1 exception1;
private E2 exception2;
private E3 exception3;
/**
* Tries to produce the result of the underlying state machine.
*
* <p>See comment of {@link ValueOrExceptionProducer#tryProduceValue}. If multiple exceptions are
* set, they are prioritized by number.
*/
@Nullable
public final V tryProduceValue(LookupEnvironment env) throws InterruptedException, E1, E2, E3 {
boolean done = driver.drive(env);
if (exception1 != null) {
throw exception1;
}
if (exception2 != null) {
throw exception2;
}
if (exception3 != null) {
throw exception3;
}
if (done) {
return checkNotNull(value);
}
return null;
}
protected final void setValue(V value) {
this.value = value;
}
protected final void setException1(E1 exception) {
this.exception1 = exception;
}
@Nullable
protected final E1 getException1() {
return exception1;
}
protected final void setException2(E2 exception) {
this.exception2 = exception;
}
@Nullable
protected final E2 getException2() {
return exception2;
}
protected final void setException3(E3 exception) {
this.exception3 = exception;
}
@Nullable
protected final E3 getException3() {
return exception3;
}
}