src/main/java/com/google/devtools/build/lib/cmdline/QueryExceptionMarkerInterface.java

// Copyright 2021 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.
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package com.google.devtools.build.lib.cmdline;

/**
 * Marker interface indicating either a {@link
 * com.google.devtools.build.lib.query2.engine.QueryException} or a {@link MarkerRuntimeException}.
 * Used with a generic type to indicate that a method can optionally throw {@code QueryException} if
 * the caller passes {@code QueryException.class} as a parameter to the method.
 *
 * <p>The only outside implementation of this interface is {@link
 * com.google.devtools.build.lib.query2.engine.QueryException}. Do not implement or extend!
 *
 * <p>Used to narrow a generic type like {@code E extends Exception} to {@code E extends Exception &
 * QueryExceptionMarkerInterface}, guaranteeing that the method will only throw {@link
 * com.google.devtools.build.lib.query2.engine.QueryException} if any exception of type E is thrown.
 * Because {@code E} will appear in the "throws" clause of a method, it must extend {@link
 * Exception}.
 */
@SuppressWarnings("InterfaceWithOnlyStatics")
public interface QueryExceptionMarkerInterface {
  /**
   * Marker class indicating that a given method does not throw QueryException. Pass {@code
   * MarkerRuntimeException.class} as a parameter.
   */
  class MarkerRuntimeException extends RuntimeException implements QueryExceptionMarkerInterface {}
}