gitea/vendor/golang.org/x/xerrors/fmt.go

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// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package xerrors
import (
"fmt"
"strings"
"golang.org/x/xerrors/internal"
)
// Errorf formats according to a format specifier and returns the string as a
// value that satisfies error.
//
// The returned error includes the file and line number of the caller when
// formatted with additional detail enabled. If the last argument is an error
// the returned error's Format method will return it if the format string ends
// with ": %s", ": %v", or ": %w". If the last argument is an error and the
// format string ends with ": %w", the returned error implements Wrapper
// with an Unwrap method returning it.
func Errorf(format string, a ...interface{}) error {
err, wrap := lastError(format, a)
format = formatPlusW(format)
if err == nil {
return &noWrapError{fmt.Sprintf(format, a...), nil, Caller(1)}
}
// TODO: this is not entirely correct. The error value could be
// printed elsewhere in format if it mixes numbered with unnumbered
// substitutions. With relatively small changes to doPrintf we can
// have it optionally ignore extra arguments and pass the argument
// list in its entirety.
msg := fmt.Sprintf(format[:len(format)-len(": %s")], a[:len(a)-1]...)
frame := Frame{}
if internal.EnableTrace {
frame = Caller(1)
}
if wrap {
return &wrapError{msg, err, frame}
}
return &noWrapError{msg, err, frame}
}
// formatPlusW is used to avoid the vet check that will barf at %w.
func formatPlusW(s string) string {
return s
}
func lastError(format string, a []interface{}) (err error, wrap bool) {
wrap = strings.HasSuffix(format, ": %w")
if !wrap &&
!strings.HasSuffix(format, ": %s") &&
!strings.HasSuffix(format, ": %v") {
return nil, false
}
if len(a) == 0 {
return nil, false
}
err, ok := a[len(a)-1].(error)
if !ok {
return nil, false
}
return err, wrap
}
type noWrapError struct {
msg string
err error
frame Frame
}
func (e *noWrapError) Error() string {
return fmt.Sprint(e)
}
func (e *noWrapError) Format(s fmt.State, v rune) { FormatError(e, s, v) }
func (e *noWrapError) FormatError(p Printer) (next error) {
p.Print(e.msg)
e.frame.Format(p)
return e.err
}
type wrapError struct {
msg string
err error
frame Frame
}
func (e *wrapError) Error() string {
return fmt.Sprint(e)
}
func (e *wrapError) Format(s fmt.State, v rune) { FormatError(e, s, v) }
func (e *wrapError) FormatError(p Printer) (next error) {
p.Print(e.msg)
e.frame.Format(p)
return e.err
}
func (e *wrapError) Unwrap() error {
return e.err
}