1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 package org.chromium.mojo.bindings; 6 7 import org.chromium.mojo.system.Core; 8 9 import java.nio.ByteBuffer; 10 11 /** 12 * Base class for all mojo structs. 13 */ 14 public abstract class Struct { 15 /** 16 * The base size of the encoded struct. 17 */ 18 private final int mEncodedBaseSize; 19 20 /** 21 * The version of the struct. 22 */ 23 private final int mVersion; 24 25 /** 26 * Constructor. 27 */ Struct(int encodedBaseSize, int version)28 protected Struct(int encodedBaseSize, int version) { 29 mEncodedBaseSize = encodedBaseSize; 30 mVersion = version; 31 } 32 33 /** 34 * Returns the version of the struct. It is the max version of the struct in the mojom if it has 35 * been created locally, and the version of the received struct if it has been deserialized. 36 */ getVersion()37 public int getVersion() { 38 return mVersion; 39 } 40 41 /** 42 * Returns the serialization of the struct. This method can close Handles. 43 * 44 * @param core the |Core| implementation used to generate handles. Only used if the data 45 * structure being encoded contains interfaces, can be |null| otherwise. 46 */ serialize(Core core)47 public Message serialize(Core core) { 48 Encoder encoder = new Encoder(core, mEncodedBaseSize); 49 encode(encoder); 50 return encoder.getMessage(); 51 } 52 53 /** 54 * Similar to the method above, but returns the serialization result as |ByteBuffer|. 55 * 56 * @throws UnsupportedOperationException if the struct contains interfaces or handles. 57 * @throws SerializationException on serialization failure. 58 */ serialize()59 public ByteBuffer serialize() { 60 // If the struct contains interfaces which require a non-null |Core| instance, it will throw 61 // UnsupportedOperationException. 62 Message message = serialize(null); 63 64 if (!message.getHandles().isEmpty()) 65 throw new UnsupportedOperationException("Handles are discarded."); 66 67 return message.getData(); 68 } 69 70 /** 71 * Returns the serialization of the struct prepended with the given header. 72 * 73 * @param header the header to prepend to the returned message. 74 * @param core the |Core| implementation used to generate handles. Only used if the |Struct| 75 * being encoded contains interfaces, can be |null| otherwise. 76 */ serializeWithHeader(Core core, MessageHeader header)77 public ServiceMessage serializeWithHeader(Core core, MessageHeader header) { 78 Encoder encoder = new Encoder(core, mEncodedBaseSize + header.getSize()); 79 header.encode(encoder); 80 encode(encoder); 81 return new ServiceMessage(encoder.getMessage(), header); 82 } 83 84 /** 85 * Use the given encoder to serialize this data structure. 86 */ encode(Encoder encoder)87 protected abstract void encode(Encoder encoder); 88 } 89