Trait MaybeData

trait MaybeData: Debug {
    type Out;

    // Required methods
    fn on_base(
        self,
        f: impl FnOnce(ScalarRefImpl<'_>) -> Result<Value, FieldEncodeError>,
    ) -> Result<Self::Out, FieldEncodeError>;
    fn on_struct(
        self,
        st: &StructType,
        pb: &MessageDescriptor,
    ) -> Result<Self::Out, FieldEncodeError>;
    fn on_list(
        self,
        elem: &DataType,
        pb: &FieldDescriptor,
    ) -> Result<Self::Out, FieldEncodeError>;
    fn on_map(
        self,
        m: &MapType,
        pb: &MessageDescriptor,
    ) -> Result<Self::Out, FieldEncodeError>;
}

A trait that assists code reuse between validate and encode.

• For validate, the inputs are (RisingWave type, ProtoBuf type).
• For encode, the inputs are (RisingWave type, RisingWave data, ProtoBuf type).

Thus we impl MaybeData for both [()] and ScalarRefImpl.

Required Associated Types

type Out

Required Methods

fn on_base( self, f: impl FnOnce(ScalarRefImpl<'_>) -> Result<Value, FieldEncodeError>, ) -> Result<Self::Out, FieldEncodeError>

fn on_struct( self, st: &StructType, pb: &MessageDescriptor, ) -> Result<Self::Out, FieldEncodeError>

fn on_list( self, elem: &DataType, pb: &FieldDescriptor, ) -> Result<Self::Out, FieldEncodeError>

fn on_map( self, m: &MapType, pb: &MessageDescriptor, ) -> Result<Self::Out, FieldEncodeError>

Object Safety

This trait is not object safe.

Implementations on Foreign Types

impl MaybeData for ScalarRefImpl<'_>

Nullability is not part of type system in proto.

• Top level is always a message.
• All message fields can be omitted in proto3.
• All repeated elements must have a value.

So we handle ScalarRefImpl rather than DatumRef here.

type Out = Value

fn on_base( self, f: impl FnOnce(ScalarRefImpl<'_>) -> Result<Value, FieldEncodeError>, ) -> Result<Self::Out, FieldEncodeError>

fn on_struct( self, st: &StructType, pb: &MessageDescriptor, ) -> Result<Self::Out, FieldEncodeError>

fn on_list( self, elem: &DataType, pb: &FieldDescriptor, ) -> Result<Self::Out, FieldEncodeError>

fn on_map( self, m: &MapType, pb: &MessageDescriptor, ) -> Result<Self::Out, FieldEncodeError>

impl MaybeData for ()

type Out = ()

fn on_base( self, _: impl FnOnce(ScalarRefImpl<'_>) -> Result<Value, FieldEncodeError>, ) -> Result<Self::Out, FieldEncodeError>

fn on_struct( self, st: &StructType, pb: &MessageDescriptor, ) -> Result<Self::Out, FieldEncodeError>

fn on_list( self, elem: &DataType, pb: &FieldDescriptor, ) -> Result<Self::Out, FieldEncodeError>

fn on_map( self, elem: &MapType, pb: &MessageDescriptor, ) -> Result<Self::Out, FieldEncodeError>

Implementors