dev

internal/plugin/wellknown.go

@@ -0,0 +1,157 @@
+package plugin
+
+import (
+	"strings"
+
+	"google.golang.org/protobuf/reflect/protoreflect"
+)
+
+const (
+	wellKnownPrefix = "google.protobuf."
+)
+
+type WellKnown string
+
+// https://developers.google.com/protocol-buffers/docs/reference/google.protobuf
+const (
+	WellKnownAny       WellKnown = "google.protobuf.Any"
+	WellKnownDuration  WellKnown = "google.protobuf.Duration"
+	WellKnownEmpty     WellKnown = "google.protobuf.Empty"
+	WellKnownFieldMask WellKnown = "google.protobuf.FieldMask"
+	WellKnownStruct    WellKnown = "google.protobuf.Struct"
+	WellKnownTimestamp WellKnown = "google.protobuf.Timestamp"
+
+	// Wrapper types.
+	WellKnownFloatValue  WellKnown = "google.protobuf.FloatValue"
+	WellKnownInt64Value  WellKnown = "google.protobuf.Int64Value"
+	WellKnownInt32Value  WellKnown = "google.protobuf.Int32Value"
+	WellKnownUInt64Value WellKnown = "google.protobuf.UInt64Value"
+	WellKnownUInt32Value WellKnown = "google.protobuf.UInt32Value"
+	WellKnownBytesValue  WellKnown = "google.protobuf.BytesValue"
+	WellKnownDoubleValue WellKnown = "google.protobuf.DoubleValue"
+	WellKnownBoolValue   WellKnown = "google.protobuf.BoolValue"
+	WellKnownStringValue WellKnown = "google.protobuf.StringValue"
+
+	// Descriptor types.
+	WellKnownValue     WellKnown = "google.protobuf.Value"
+	WellKnownNullValue WellKnown = "google.protobuf.NullValue"
+	WellKnownListValue WellKnown = "google.protobuf.ListValue"
+)
+
+func IsWellKnownType(desc protoreflect.Descriptor) bool {
+	switch desc.(type) {
+	case protoreflect.MessageDescriptor, protoreflect.EnumDescriptor:
+		return strings.HasPrefix(string(desc.FullName()), wellKnownPrefix)
+	default:
+		return false
+	}
+}
+
+func WellKnownType(desc protoreflect.Descriptor) (WellKnown, bool) {
+	if !IsWellKnownType(desc) {
+		return "", false
+	}
+	return WellKnown(desc.FullName()), true
+}
+
+func (wkt WellKnown) Name() string {
+	return "wellKnown" + strings.TrimPrefix(string(wkt), wellKnownPrefix)
+}
+
+func (wkt WellKnown) TypeDeclaration() string {
+	var w writer
+	switch wkt {
+	case WellKnownAny:
+		w.P("// If the Any contains a value that has a special JSON mapping,")
+		w.P("// it will be converted as follows:")
+		w.P("// {\"@type\": xxx, \"value\": yyy}.")
+		w.P("// Otherwise, the value will be converted into a JSON object,")
+		w.P("// and the \"@type\" field will be inserted to indicate the actual data type.")
+		w.P("interface ", wkt.Name(), " {")
+		w.P("  ", "\"@type\": string;")
+		w.P("  [key: string]: unknown;")
+		w.P("}")
+	case WellKnownDuration:
+		w.P("// Generated output always contains 0, 3, 6, or 9 fractional digits,")
+		w.P("// depending on required precision, followed by the suffix \"s\".")
+		w.P("// Accepted are any fractional digits (also none) as long as they fit")
+		w.P("// into nano-seconds precision and the suffix \"s\" is required.")
+		w.P("type ", wkt.Name(), " = string;")
+	case WellKnownEmpty:
+		w.P("// An empty JSON object")
+		w.P("type ", wkt.Name(), " = Record<never, never>;")
+	case WellKnownTimestamp:
+		w.P("// Encoded using RFC 3339, where generated output will always be Z-normalized")
+		w.P("// and uses 0, 3, 6 or 9 fractional digits.")
+		w.P("// Offsets other than \"Z\" are also accepted.")
+		w.P("type ", wkt.Name(), " = string;")
+	case WellKnownFieldMask:
+		w.P("// In JSON, a field mask is encoded as a single string where paths are")
+		w.P("// separated by a comma. Fields name in each path are converted")
+		w.P("// to/from lower-camel naming conventions.")
+		w.P("// As an example, consider the following message declarations:")
+		w.P("//")
+		w.P("//     message Profile {")
+		w.P("//       User user = 1;")
+		w.P("//       Photo photo = 2;")
+		w.P("//     }")
+		w.P("//     message User {")
+		w.P("//       string display_name = 1;")
+		w.P("//       string address = 2;")
+		w.P("//     }")
+		w.P("//")
+		w.P("// In proto a field mask for `Profile` may look as such:")
+		w.P("//")
+		w.P("//     mask {")
+		w.P("//       paths: \"user.display_name\"")
+		w.P("//       paths: \"photo\"")
+		w.P("//     }")
+		w.P("//")
+		w.P("// In JSON, the same mask is represented as below:")
+		w.P("//")
+		w.P("//     {")
+		w.P("//       mask: \"user.displayName,photo\"")
+		w.P("//     }")
+		w.P("type ", wkt.Name(), " = string;")
+	case WellKnownFloatValue,
+		WellKnownDoubleValue,
+		WellKnownInt64Value,
+		WellKnownInt32Value,
+		WellKnownUInt64Value,
+		WellKnownUInt32Value:
+		w.P("type ", wkt.Name(), " = number | null;")
+	case WellKnownBytesValue, WellKnownStringValue:
+		w.P("type ", wkt.Name(), " = string | null;")
+	case WellKnownBoolValue:
+		w.P("type ", wkt.Name(), " = boolean | null;")
+	case WellKnownStruct:
+		w.P("// Any JSON value.")
+		w.P("type ", wkt.Name(), " = Record<string, unknown>;")
+	case WellKnownValue:
+		w.P("type ", wkt.Name(), " = unknown;")
+	case WellKnownNullValue:
+		w.P("type ", wkt.Name(), " = null;")
+	case WellKnownListValue:
+		w.P("type ", wkt.Name(), " = ", WellKnownValue.Name(), "[];")
+	default:
+		w.P("// No mapping for this well known type is generated, yet.")
+		w.P("type ", wkt.Name(), " = unknown;")
+	}
+	return w.String()
+}
+
+type writer struct {
+	b strings.Builder
+}
+
+func (w *writer) P(ss ...string) {
+	for _, s := range ss {
+		// strings.Builder never returns an error, so safe to ignore
+		_, _ = w.b.WriteString(s)
+	}
+	_, _ = w.b.WriteString("\n")
+}
+
+func (w *writer) String() string {
+	return w.b.String()
+}