java/core/src/main/java/com/google/protobuf/GeneratedMessageInfoFactory.java

// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd

package com.google.protobuf;

/** A factory for message info that is generated into the message itself. */
@ExperimentalApi
class GeneratedMessageInfoFactory implements MessageInfoFactory {

  private static final GeneratedMessageInfoFactory instance = new GeneratedMessageInfoFactory();

  // Disallow construction - it's a singleton.
  private GeneratedMessageInfoFactory() {}

  public static GeneratedMessageInfoFactory getInstance() {
    return instance;
  }

  @Override
  public boolean isSupported(Class<?> messageType) {
    return GeneratedMessageLite.class.isAssignableFrom(messageType);
  }

  @Override
  public MessageInfo messageInfoFor(Class<?> messageType) {
    if (!GeneratedMessageLite.class.isAssignableFrom(messageType)) {
      throw new IllegalArgumentException("Unsupported message type: " + messageType.getName());
    }

    try {
      return (MessageInfo) GeneratedMessageLite.getDefaultInstance(
          messageType.asSubclass(GeneratedMessageLite.class))
          .buildMessageInfo();
    } catch (Exception e) {
      throw new RuntimeException("Unable to get message info for " + messageType.getName(), e);
    }
  }
}