/// <summary> /// Performs initialization for the given generic type argument. /// </summary> /// <remarks> /// This method is present for the sake of AOT compilers. It allows code (whether handwritten or generated) /// to make calls into the reflection machinery of this library to express an intention to use that type /// reflectively (e.g. for JSON parsing and formatting). The call itself does almost nothing, but AOT compilers /// attempting to determine which generic type arguments need to be handled will spot the code path and act /// accordingly. /// </remarks> /// <typeparam name="T">The type to force initialization for.</typeparam> public static void ForceReflectionInitialization <T>() => ReflectionUtil.ForceInitialize <T>();
internal SingleFieldAccessor(PropertyInfo property, FieldDescriptor descriptor) : base(property, descriptor)
{
if (!property.CanWrite)
{
throw new ArgumentException("Not all required properties/methods available");
}
setValueDelegate = ReflectionUtil.CreateActionIMessageObject(property.GetSetMethod());
// Note: this looks worrying in that we access the containing oneof, which isn't valid until cross-linking
// is complete... but field accessors aren't created until after cross-linking.
// The oneof itself won't be cross-linked yet, but that's okay: the oneof accessor is created
// earlier.
// Message fields always support presence, via null checks.
if (descriptor.FieldType == FieldType.Message)
{
hasDelegate = message => GetValue(message) != null;
clearDelegate = message => SetValue(message, null);
}
// Oneof fields always support presence, via case checks.
// Note that clearing the field is a no-op unless that specific field is the current "case".
else if (descriptor.RealContainingOneof != null)
{
var oneofAccessor = descriptor.RealContainingOneof.Accessor;
hasDelegate = message => oneofAccessor.GetCaseFieldDescriptor(message) == descriptor;
clearDelegate = message =>
{
// Clear on a field only affects the oneof itself if the current case is the field we're accessing.
if (oneofAccessor.GetCaseFieldDescriptor(message) == descriptor)
{
oneofAccessor.Clear(message);
}
};
}
// Primitive fields always support presence in proto2, and support presence in proto3 for optional fields.
else if (descriptor.File.Syntax == Syntax.Proto2 || descriptor.Proto.Proto3Optional)
{
MethodInfo hasMethod = property.DeclaringType.GetRuntimeProperty("Has" + property.Name).GetMethod;
if (hasMethod == null)
{
throw new ArgumentException("Not all required properties/methods are available");
}
hasDelegate = ReflectionUtil.CreateFuncIMessageBool(hasMethod);
MethodInfo clearMethod = property.DeclaringType.GetRuntimeMethod("Clear" + property.Name, ReflectionUtil.EmptyTypes);
if (clearMethod == null)
{
throw new ArgumentException("Not all required properties/methods are available");
}
clearDelegate = ReflectionUtil.CreateActionIMessage(clearMethod);
}
// What's left?
// Primitive proto3 fields without the optional keyword, which aren't in oneofs.
else
{
hasDelegate = message => { throw new InvalidOperationException("Presence is not implemented for this field"); };
// While presence isn't supported, clearing still is; it's just setting to a default value.
var clrType = property.PropertyType;
object defaultValue =
clrType == typeof(string) ? ""
: clrType == typeof(ByteString) ? ByteString.Empty
: Activator.CreateInstance(clrType);
clearDelegate = message => SetValue(message, defaultValue);
}
}