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FBS Annotations
FlatSharp supports the general FBS syntax. It does not implement every feature, but tries to warn you in those cases. It also supports some custom extensions that are specific to FlatSharp schemas. Those are documented here.
Description: Instructs the FlatSharp compiler to pre-generate a serializer for this type and all that it encompasses. Only one serializer may be generated per type. Without this option, FlatSharp will only generate the data contracts. Precompiled Serializers are required for types exposed in gRPC definitions.
Valid On: Tables only
Value Required: False
Default Value: Default
Valid Values:
- Default (GreedyMutable)
- GreedyMutable
- Greedy
- VectorCacheMutable
- VectorCache
- PropertyCache
- Lazy
Examples:
// Table with a default precompiled serializer
table MyTable (PrecompiledSerializer) { Value : int; }
// Table with a lazy precompiled serializer
table LazyTable (PrecompiledSerializer:"Lazy") { Value : int; }
Description: Marks a single field (or all the fields in a table/struct) as being non-virtual in the generated C#. Non-Virtual properties are deserialized greedily and perform faster due to JIT inlining.
Valid On: Tables, Structs, and Fields
Value Required: False
Default Value: true
Valid Values:
- True
- False
Examples:
// Table that marks all fields as non-virtual
table MyTable (PrecompiledSerializer, NonVirtual:"true")
{
Value : int; // Inherits the NonVirtual setting from the table.
Value2 : int (NonVirtual:"false"); // overrides the table setting for this field. This will be generated as a virtual property.
}
Description: Controls how a property setter is generated for the given field. This, along with the ObsoleteDefaultConstructor attribute
can assist in defining immutable objects.
Valid On: Fields
Value Required: False
Default Value: Public
Valid Values:
- None
- ProtectedInternal
- Protected
- Public
Examples:
table MyTable
{
Value : int; // generates a public setter property.
Value2 : int (Setter:"None"); // does not generate a setter property.
Value3 : int (Setter:"ProtectedInternal"); // generates a setter with the "protected internal" access modifier
Value4 : int (Setter:"Protected"); // generates a setter with the "protected" modifier.
Value5 : int (Setter:"Public"); // generates a setter with the "public" modifier.
}
Description: Controls the type of vector generated.
Valid On: Vector fields
Value Required: False
Default Value: IList
Valid Values:
- IList
- IReadOnlyList
- Array
- Memory
- ReadOnlyMemory
- IIndexedVector
Examples:
table MyTable
{
// Generates an IList<int> vector
Value : [int];
// Generates an IList<int> vector
Value2 : [int] (VectorType:"IList");
// Vector of type IReadOnlyList<int>
Value3 : [int] (VectorType:"IReadOnlyList");
// Vector of type Memory<byte>. Depending on deserialization mode, this may map a raw segment
// of the input buffer. Memory vectors only support unsigned bytes.
Value4 : [ubyte] (VectorType:"Memory")
// Same as above, but with ReadOnlyMemory<byte>
Value5 : [int] (VectorType:"ReadOnlyMemory");
// Generates an int[] vector. Array vectors cannot be lazily allocated.
Value6 : [int] (VectorType:"Array");
// Generates an IIndexedVector<OtherTable> vector. Indexed vectors are always sorted, can only
// contain tables, and those tables must have a 'Key' attribute specified.
Value7 : [OtherTable] (VectorType:"IIndexedVector");
}
Description: Controls whether a given vector is sorted at serialization time. Sorted Vectors must contain tables, and the tables must have a single field with the Key attribute.
Valid On: Vector fields
Value Required: False
Default Value: True
Valid Values:
- True
- False
Examples:
table MyTable
{
Value : [ItemTable] (SortedVector);
}
table ItemTable
{
Value : string (Key);
}
Description: Indicates that the field in a given table that should be used as the sort key when the table is used as the item of a sorted vector.
Valid On: Table fields of type string, int8, uint8, int16, uint16, int32, uint32, int64, uint64, float, or double.
Value Required: False
Default Value: True
Valid Values:
- True
- False
Examples:
table MyTable
{
Value : [ItemTable] (SortedVector);
}
table ItemTable
{
Value : string (Key);
}
Description: The given string field or string vector should be a SharedString. SharedStrings are FlatSharp's way of enabling string reuse inside a buffer, which can lead to smaller buffers and better performance in some cases. Note that simply enabling SharedStrings is not enough to enable string sharing. Please refer to the Shared Strings sample for more information.
Valid On: String fields and String Vectors in tables.
Value Required: False
Default Value: True
Valid Values:
- True
- False
Examples:
table MyTable
{
// Generates an IList<SharedString> vector
Value : [string] (SharedString);
// Generates a SharedString field
Value2 : string (SharedString);
}
Description: FlatSharp requires that serialized objects expose a public, parameterless default constructor. This option flags that
default constructor on generated tables and structs with the [Obsolete] attribute, which can prevent user code from invoking
a constructor that does not properly initialize the object. This, along with the Setter attribute, can assist with creating immutable objects
Valid On: Tables and Structs
Value Required: False
Default Value: True
Valid Values:
- True
- False
Examples:
table MyTable (ObsoleteDefaultConstructor)
{
Value : int;
}
Description: FlatSharp generates custom Union types for unions defined in FBS files. Use of this attribute tells FlatSharp to not generate such a type and rely on the built-in FlatBufferUnion<T> type instead. This is primarily intended to support legacy scenarios that predate union custom types.
Valid On: Unions
Value Required: False
Default Value: True
Valid Values: None. Presence of the attribute is all that matters.
Examples:
// Generated code will contain 'FlatBufferUnion<Dog, Cat, Fish>' instead of 'BasicPet'
union BasicPet (NoCustomType) { Dog, Cat, Fish }