1 #region Copyright notice and license 2 // Protocol Buffers - Google's data interchange format 3 // Copyright 2015 Google Inc. All rights reserved. 4 // https://developers.google.com/protocol-buffers/ 5 // 6 // Redistribution and use in source and binary forms, with or without 7 // modification, are permitted provided that the following conditions are 8 // met: 9 // 10 // * Redistributions of source code must retain the above copyright 11 // notice, this list of conditions and the following disclaimer. 12 // * Redistributions in binary form must reproduce the above 13 // copyright notice, this list of conditions and the following disclaimer 14 // in the documentation and/or other materials provided with the 15 // distribution. 16 // * Neither the name of Google Inc. nor the names of its 17 // contributors may be used to endorse or promote products derived from 18 // this software without specific prior written permission. 19 // 20 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 21 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 22 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 23 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 24 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 25 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 26 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 30 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 #endregion 32 33 using System; 34 using System.Reflection; 35 using Google.Protobuf.Compatibility; 36 37 namespace Google.Protobuf.Reflection 38 { 39 /// <summary> 40 /// Accessor for single fields. 41 /// </summary> 42 internal sealed class SingleFieldAccessor : FieldAccessorBase 43 { 44 // All the work here is actually done in the constructor - it creates the appropriate delegates. 45 // There are various cases to consider, based on the property type (message, string/bytes, or "genuine" primitive) 46 // and proto2 vs proto3 for non-message types, as proto3 doesn't support "full" presence detection or default 47 // values. 48 49 private readonly Action<IMessage, object> setValueDelegate; 50 private readonly Action<IMessage> clearDelegate; 51 private readonly Func<IMessage, bool> hasDelegate; 52 SingleFieldAccessor(PropertyInfo property, FieldDescriptor descriptor)53 internal SingleFieldAccessor(PropertyInfo property, FieldDescriptor descriptor) : base(property, descriptor) 54 { 55 if (!property.CanWrite) 56 { 57 throw new ArgumentException("Not all required properties/methods available"); 58 } 59 setValueDelegate = ReflectionUtil.CreateActionIMessageObject(property.GetSetMethod()); 60 61 // Note: this looks worrying in that we access the containing oneof, which isn't valid until cross-linking 62 // is complete... but field accessors aren't created until after cross-linking. 63 // The oneof itself won't be cross-linked yet, but that's okay: the oneof accessor is created 64 // earlier. 65 66 // Message fields always support presence, via null checks. 67 if (descriptor.FieldType == FieldType.Message) 68 { 69 hasDelegate = message => GetValue(message) != null; 70 clearDelegate = message => SetValue(message, null); 71 } 72 // Oneof fields always support presence, via case checks. 73 // Note that clearing the field is a no-op unless that specific field is the current "case". 74 else if (descriptor.RealContainingOneof != null) 75 { 76 var oneofAccessor = descriptor.RealContainingOneof.Accessor; 77 hasDelegate = message => oneofAccessor.GetCaseFieldDescriptor(message) == descriptor; 78 clearDelegate = message => 79 { 80 // Clear on a field only affects the oneof itself if the current case is the field we're accessing. 81 if (oneofAccessor.GetCaseFieldDescriptor(message) == descriptor) 82 { 83 oneofAccessor.Clear(message); 84 } 85 }; 86 } 87 // Primitive fields always support presence in proto2, and support presence in proto3 for optional fields. 88 else if (descriptor.File.Syntax == Syntax.Proto2 || descriptor.Proto.Proto3Optional) 89 { 90 MethodInfo hasMethod = property.DeclaringType.GetRuntimeProperty("Has" + property.Name).GetMethod; 91 if (hasMethod == null) 92 { 93 throw new ArgumentException("Not all required properties/methods are available"); 94 } 95 hasDelegate = ReflectionUtil.CreateFuncIMessageBool(hasMethod); 96 MethodInfo clearMethod = property.DeclaringType.GetRuntimeMethod("Clear" + property.Name, ReflectionUtil.EmptyTypes); 97 if (clearMethod == null) 98 { 99 throw new ArgumentException("Not all required properties/methods are available"); 100 } 101 clearDelegate = ReflectionUtil.CreateActionIMessage(clearMethod); 102 } 103 // What's left? 104 // Primitive proto3 fields without the optional keyword, which aren't in oneofs. 105 else 106 { 107 hasDelegate = message => { throw new InvalidOperationException("Presence is not implemented for this field"); }; 108 109 // While presence isn't supported, clearing still is; it's just setting to a default value. 110 var clrType = property.PropertyType; 111 112 object defaultValue = 113 clrType == typeof(string) ? "" 114 : clrType == typeof(ByteString) ? ByteString.Empty 115 : Activator.CreateInstance(clrType); 116 clearDelegate = message => SetValue(message, defaultValue); 117 } 118 } 119 120 public override void Clear(IMessage message) => clearDelegate(message); 121 public override bool HasValue(IMessage message) => hasDelegate(message); SetValue(IMessage message, object value)122 public override void SetValue(IMessage message, object value) => setValueDelegate(message, value); 123 } 124 } 125