protoc-gen-cue

README

protoc-gen-cue

This protoc plugin generates CUE files.

Conversions

Complies with protojson.

Basic Types

Proto Type	CUE Type	Comments
map<K, V>	{ [string]: V }	All keys are converted to strings.
repeated V	[...V]
bool	*false | bool
string	*"" | string
bytes	*'' | bytes
int32	*0 | int32
fixed32	*0 | int32
uint32	*0 | uint32
int64	*0 | int64
fixed64	*0 | fixed64
uint32	*0 | uint64
float	*0 | float32
double	*0 | float64
Any	*null | { "@type": string, ... }
Struct	*null | { [string]: _ }
Value	*null | _
ListValue	*null | [...]
NullValue	*null | null
BoolValue	*null | bool
StringValue	*null | string
Int32Value	*null | int32
UInt32Value	*null | uint32
Int64Value	*null | int64
UInt64Value	*null | uint64
FloatValue	*null | float32
DoubleValue	*null | double
Empty	*null | close({})
Timestamp	*null | string	See the Timestamp section for more information.
Duration	*null | string	See the Duration section for more information.
FieldMask	*null | { paths: [...string] }

Message

import "github.com/ornew/protoc-gen-cue/pkg/options/cue.proto";

message Foo {
  string name = 1 [(cue.field).expr = '!="xxx"'];
  int32 age = 2 [(cue.field).expr = '<100'];
  int32 age_next_year = 3 [(cue.field).expr = 'age+1'];
}

To:

#Foo: {
  name: *"" | string
  name: !="xxx"
  age: *0 | int32
  age: <100
  ageNextYear: *0 | int32
  ageNextYear: age+1
}

Enum

enum Bar {
  ZERO = 0;
  ONE = 1;
}

To:

#Bar: *#Bar_ZERO | #Bar_ONE

#Bar_ZERO: "ZERO"
#Bar_ONE:  "ONE"

Oneof

message Car {
  oneof id {
    string product_name = 1;
    int32 serial_number = 2;
  }
}

To:

#Car: {
  _oneof_id: productName & serialNumber
  productName?: string
  serialNumber?: int32
}

Timestamp

Currently defined by an unconstrained string. This is due to the fact that CUE's built-in time.Time constraint is incompatible with the JSON format defined in the timestamppb. We plan to fix this issue in a future version to follow the original format. See for more details: time.Time on pkg.go.dev and timestamppb.Timestamp

Duration

Currently defined by an unconstrained string. This is due to the fact that CUE's built-in time.Duration constraint is incompatible with the JSON format defined in the durationpb. We plan to fix this issue in a future version to follow the original format. See for more details: time.Duration in pkg.go.dev and descriptorpb.Duration

Optional (proto3)

message Dog {
  optional string nick_name = 1;
}

To:

#Dog: {
  nickName?: string
}