Function buildUnionTypeData

codegen/service/service_data.go:1101–1141

buildUnionTypeData creates the data needed to generate a sum-type union struct, its discriminator kind, and branch metadata.

(u *expr.Union, scope *codegen.NameScope, loc *codegen.Location)

// buildUnionTypeData creates the data needed to generate a sum-type union
// struct, its discriminator kind, and branch metadata.
func buildUnionTypeData(u *expr.Union, scope *codegen.NameScope, loc *codegen.Location) *UnionTypeData {
	att := &expr.AttributeExpr{Type: u}
	name := scope.GoTypeName(att)
	kindName := scope.Unique(name + "Kind")
	unionPkg := loc.PackageName()

	fields := make([]*UnionFieldData, len(u.Values))
	for i, nat := range u.Values {
		fieldName := codegen.Goify(nat.Name, true)
		var pkg string
		if tloc := codegen.UserTypeLocation(nat.Attribute.Type); tloc != nil {
			pkg = tloc.PackageName()
			if pkg == unionPkg {
				pkg = ""
			}
		}
		fieldType := scope.GoFullTypeRef(nat.Attribute, pkg)
		primitiveAliasType, hasPrimitiveAlias := primitiveAliasGoType(nat.Attribute.Type)
		_, isUserType := nat.Attribute.Type.(expr.UserType)
		emitPrimitiveAlias := hasPrimitiveAlias && !isUserType && pkg == ""
		kindConst := kindName + codegen.Goify(nat.Name, true)
		fields[i] = &UnionFieldData{
			Name:               nat.Name,
			KindConst:          kindConst,
			FieldName:          fieldName,
			FieldType:          fieldType,
			EmitPrimitiveAlias: emitPrimitiveAlias,
			PrimitiveAliasType: primitiveAliasType,
			TypeTag:            nat.Name,
		}
	}

	return &UnionTypeData{
		Name:     name,
		KindName: kindName,
		Fields:   fields,
		Loc:      loc,
		TypeKey:  u.GetTypeKey(),
		ValueKey: u.GetValueKey(),
	}
}

// collectViewUnionTypes traverses the attribute to gather all union sum-type
// definitions referenced by view-projected types. It always uses the provided