Protobuf → Component

Note: This mapping is currently only meant for the proto3 language, though it could be adapted to proto2.

Scalar Value Types

Protobuf	WIT
`float`	`float32`
`double`	`float64`
`int32` `sint32` `sfixed32`	`s32`
`int64` `sint64` `sfixed64`	`s64`
`uint32` `fixed32`	`u32`
`uint64` `fixed64`	`u64`
`bool`	`bool`
`string`	`string`
`bytes`	`list<u8>`

Enums

Enums are mapped to WIT variants. Each enum constant name is mapped to a variant case. Additionally, an extra case is defined with payload type i32 to store unknown enum values, e.g. unknown-value(i32)

TODO: Decide on a standard "unknown value" case name and how to resolve name collisions.

TODO: Consider generating functions to convert between enum constant and variant values.

Messages

Messages are mapped to WIT records.

Message names are mapped to kebab-case for the record name.

TBD: nested message name scoping

Fields are mapped in order of increasing tag number. Field names are mapped by converting to kebab-case.

An optional field is mapped by wrapping its type with option<...>.

A repeated field is mapped by wrapping its type with list<...>.

A oneof is mapped to a WIT variant. The first case of the variant is unset, and the other cases correspond to the fields of the oneof.

TBD: what if one of the fields is named unset?

A map<K,V> is mapped (!) to a WIT list<tuple<K, V>>.