newline battles continue

vendor/go.mongodb.org/mongo-driver/internal/error.go

@@ -0,0 +1,119 @@
+// Copyright (C) MongoDB, Inc. 2017-present.
+//
+// Licensed under the Apache License, Version 2.0 (the "License"); you may
+// not use this file except in compliance with the License. You may obtain
+// a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+
+package internal
+
+import (
+	"fmt"
+)
+
+// WrappedError represents an error that contains another error.
+type WrappedError interface {
+	// Message gets the basic message of the error.
+	Message() string
+	// Inner gets the inner error if one exists.
+	Inner() error
+}
+
+// RolledUpErrorMessage gets a flattened error message.
+func RolledUpErrorMessage(err error) string {
+	if wrappedErr, ok := err.(WrappedError); ok {
+		inner := wrappedErr.Inner()
+		if inner != nil {
+			return fmt.Sprintf("%s: %s", wrappedErr.Message(), RolledUpErrorMessage(inner))
+		}
+
+		return wrappedErr.Message()
+	}
+
+	return err.Error()
+}
+
+//UnwrapError attempts to unwrap the error down to its root cause.
+func UnwrapError(err error) error {
+
+	switch tErr := err.(type) {
+	case WrappedError:
+		return UnwrapError(tErr.Inner())
+	case *multiError:
+		return UnwrapError(tErr.errors[0])
+	}
+
+	return err
+}
+
+// WrapError wraps an error with a message.
+func WrapError(inner error, message string) error {
+	return &wrappedError{message, inner}
+}
+
+// WrapErrorf wraps an error with a message.
+func WrapErrorf(inner error, format string, args ...interface{}) error {
+	return &wrappedError{fmt.Sprintf(format, args...), inner}
+}
+
+// MultiError combines multiple errors into a single error. If there are no errors,
+// nil is returned. If there is 1 error, it is returned. Otherwise, they are combined.
+func MultiError(errors ...error) error {
+
+	// remove nils from the error list
+	var nonNils []error
+	for _, e := range errors {
+		if e != nil {
+			nonNils = append(nonNils, e)
+		}
+	}
+
+	switch len(nonNils) {
+	case 0:
+		return nil
+	case 1:
+		return nonNils[0]
+	default:
+		return &multiError{
+			message: "multiple errors encountered",
+			errors:  nonNils,
+		}
+	}
+}
+
+type multiError struct {
+	message string
+	errors  []error
+}
+
+func (e *multiError) Message() string {
+	return e.message
+}
+
+func (e *multiError) Error() string {
+	result := e.message
+	for _, e := range e.errors {
+		result += fmt.Sprintf("\n  %s", e)
+	}
+	return result
+}
+
+func (e *multiError) Errors() []error {
+	return e.errors
+}
+
+type wrappedError struct {
+	message string
+	inner   error
+}
+
+func (e *wrappedError) Message() string {
+	return e.message
+}
+
+func (e *wrappedError) Error() string {
+	return RolledUpErrorMessage(e)
+}
+
+func (e *wrappedError) Inner() error {
+	return e.inner
+}