Function OneOf

dsl/attribute.go:221–292

OneOf creates a union type from a name and a list of attributes. OneOf may be used wherever Attribute can. OneOf takes a name as first argument, a description as optional second argument and a function that lists the union types as last argument. Example: var PetOwner = Type("PetOwner", func()

(name string, args ...any)

//	    })
//	})
func OneOf(name string, args ...any) {
	if len(args) == 0 {
		eval.TooFewArgError()
		return
	}
	if len(args) > 2 {
		eval.TooManyArgError()
		return
	}
	fn, ok := args[len(args)-1].(func())
	if !ok {
		eval.InvalidArgError("function", args[len(args)-1])
	}
	var desc string
	if len(args) > 1 {
		desc, ok = args[0].(string)
		if !ok {
			eval.InvalidArgError("string", args[0])
		}
	}
	Attribute(name, &expr.Union{TypeName: name}, desc, fn)

	// Extract and validate oneof:type:field and oneof:value:field meta tags
	var parent *expr.AttributeExpr
	switch def := eval.Current().(type) {
	case *expr.AttributeExpr:
		parent = def
	case expr.CompositeExpr:
		parent = def.Attribute()
	default:
		return
	}
	if parent == nil {
		return
	}

	// Find the union attribute we just created
	attr := parent.Find(name)
	if attr == nil || attr.Meta == nil {
		return
	}

	union, ok := attr.Type.(*expr.Union)
	if !ok {
		return
	}

	// Extract type key from meta
	if typeKeys, ok := attr.Meta["oneof:type:field"]; ok && len(typeKeys) > 0 {
		typeKey := typeKeys[0]
		if typeKey == "" {
			eval.ReportError("oneof:type:field meta cannot be empty")
			return
		}
		union.TypeKey = typeKey
	}

	// Extract value key from meta