group.go

package errors

// ErrorGroup is an interface for multiple errors that are not a chain.
// This happens for example when executing multiple operations in parallel.
type ErrorGroup interface {
	Errors() []error
}

// Errors uses the ErrorGroup interface to return a slice of errors.
// If the ErrorGroup interface is not implemented it returns an array containing just the given error.
func Errors(err error) []error {
	if eg, ok := err.(ErrorGroup); ok {
		return eg.Errors()
	}
	return []error{err}
}

// WalkDeep does a depth-first traversal of all errors.
// Any ErrorGroup is traversed (after going deep).
// The visitor function can return true to end the traversal early
// In that case, WalkDeep will return true, otherwise false.
func WalkDeep(err error, visitor func(err error) bool) bool {
	// Go deep
	unErr := err
	for unErr != nil {
		if done := visitor(unErr); done {
			return true
		}
		unErr = Unwrap(unErr)
	}

	// Go wide
	if group, ok := err.(ErrorGroup); ok {
		for _, err := range group.Errors() {
			if early := WalkDeep(err, visitor); early {
				return true
			}
		}
	}

	return false
}