/// <summary>
/// Generates a special property getter for union types. This stems from
/// the fact that unions occupy two spots in the table's vtable to deserialize one
/// logical field. This means that the logic to read them must also be special.
/// </summary>
private GeneratedProperty CreateUnionTableGetter(TableMemberModel memberModel, int index)
{
Type propertyType = memberModel.ItemTypeModel.ClrType;
string defaultValue = CSharpHelpers.GetDefaultValueToken(memberModel);
UnionTypeModel unionModel = (UnionTypeModel)memberModel.ItemTypeModel;
GeneratedProperty generatedProperty = new GeneratedProperty(this.options, index, memberModel.PropertyInfo);
// Start by generating switch cases. The codegen'ed union types have
// well-defined constructors for each constituent type, so this .ctor
// will always be available.
List <string> switchCases = new List <string>();
for (int i = 0; i < unionModel.UnionElementTypeModel.Length; ++i)
{
var unionMember = unionModel.UnionElementTypeModel[i];
int unionIndex = i + 1;
string structOffsetAdjustment = string.Empty;
if (unionMember.SchemaType == FlatBufferSchemaType.Struct)
{
structOffsetAdjustment = $"offsetLocation += buffer.{nameof(InputBuffer.ReadUOffset)}(offsetLocation);";
}
string @case =
$@"
case {unionIndex}:
{structOffsetAdjustment}
return new {CSharpHelpers.GetCompilableTypeName(unionModel.ClrType)}({this.GetReadInvocation(unionMember.ClrType, "buffer", "offsetLocation")});
";
switchCases.Add(@case);
}
generatedProperty.ReadValueMethodDefinition =
$@"
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static {CSharpHelpers.GetCompilableTypeName(propertyType)} {generatedProperty.ReadValueMethodName}(InputBuffer buffer, int offset)
{{
int discriminatorLocation = buffer.{nameof(InputBuffer.GetAbsoluteTableFieldLocation)}(offset, {index});
int offsetLocation = buffer.{nameof(InputBuffer.GetAbsoluteTableFieldLocation)}(offset, {index + 1});
if (discriminatorLocation == 0) {{
return {defaultValue};
}}
else {{
byte discriminator = buffer.{nameof(InputBuffer.ReadByte)}(discriminatorLocation);
if (discriminator == 0 && offsetLocation != 0)
throw new System.IO.InvalidDataException(""FlatBuffer union had discriminator set but no offset."");
switch (discriminator)
{{
{string.Join("\r\n", switchCases)}
default:
return {defaultValue};
}}
}}
}}
";
return(generatedProperty);
}
private void ImplementStructReadMethod(StructTypeModel typeModel)
{
// We have to implement two items: The table class and the overall "read" method.
// Let's start with the read method.
string className = "structReader_" + Guid.NewGuid().ToString("n");
// Static factory method.
this.GenerateMethodDefinition(typeModel.ClrType, $"return new {className}(memory, offset);");
// Implement the class
{
// Build up a list of property overrides.
var propertyOverrides = new List <GeneratedProperty>();
for (int index = 0; index < typeModel.Members.Count; ++index)
{
var value = typeModel.Members[index];
PropertyInfo propertyInfo = value.PropertyInfo;
Type propertyType = propertyInfo.PropertyType;
string compilableTypeName = CSharpHelpers.GetCompilableTypeName(propertyType);
GeneratedProperty generatedProperty = new GeneratedProperty(this.options, index, propertyInfo);
generatedProperty.ReadValueMethodDefinition =
$@"
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static {CSharpHelpers.GetCompilableTypeName(propertyType)} {generatedProperty.ReadValueMethodName}(InputBuffer buffer, int offset)
{{
return {this.GetReadInvocation(propertyType, "buffer", $"offset + {value.Offset}")};
}}
";
propertyOverrides.Add(generatedProperty);
}
string classDefinition = this.CreateClass(
className,
typeModel.ClrType,
typeModel.Members.Select(x => x.PropertyInfo.Name),
propertyOverrides);
var node = CSharpSyntaxTree.ParseText(classDefinition, ParseOptions);
this.methodDeclarations.Add(node.GetRoot());
}
}
/// <summary>
/// Generates a standard getter for a normal vtable entry.
/// </summary>
private GeneratedProperty CreateStandardTableProperty(TableMemberModel memberModel, int index)
{
Type propertyType = memberModel.ItemTypeModel.ClrType;
string defaultValue = CSharpHelpers.GetDefaultValueToken(memberModel);
GeneratedProperty property = new GeneratedProperty(this.options, index, memberModel.PropertyInfo);
property.ReadValueMethodDefinition =
$@"
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static {CSharpHelpers.GetCompilableTypeName(propertyType)} {property.ReadValueMethodName}(InputBuffer buffer, int offset)
{{
int absoluteLocation = buffer.{nameof(InputBuffer.GetAbsoluteTableFieldLocation)}(offset, {index});
if (absoluteLocation == 0) {{
return {defaultValue};
}}
else {{
return {this.GetReadInvocation(propertyType, "buffer", "absoluteLocation")};
}}
}}
";
return(property);
}
