+++ /dev/null
-// 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"
- "unicode"
- "unicode/utf8"
-
- "golang.org/x/xerrors/internal"
-)
-
-const percentBangString = "%!"
-
-// 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 an Unwrap
-// method returning it.
-//
-// If the format specifier includes a %w verb with an error operand in a
-// position other than at the end, the returned error will still implement an
-// Unwrap method returning the operand, but the error's Format method will not
-// return the wrapped error.
-//
-// It is invalid to include more than one %w verb or to supply it with an
-// operand that does not implement the error interface. The %w verb is otherwise
-// a synonym for %v.
-func Errorf(format string, a ...interface{}) error {
- format = formatPlusW(format)
- // Support a ": %[wsv]" suffix, which works well with xerrors.Formatter.
- wrap := strings.HasSuffix(format, ": %w")
- idx, format2, ok := parsePercentW(format)
- percentWElsewhere := !wrap && idx >= 0
- if !percentWElsewhere && (wrap || strings.HasSuffix(format, ": %s") || strings.HasSuffix(format, ": %v")) {
- err := errorAt(a, len(a)-1)
- 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}
- }
- // Support %w anywhere.
- // TODO: don't repeat the wrapped error's message when %w occurs in the middle.
- msg := fmt.Sprintf(format2, a...)
- if idx < 0 {
- return &noWrapError{msg, nil, Caller(1)}
- }
- err := errorAt(a, idx)
- if !ok || err == nil {
- // Too many %ws or argument of %w is not an error. Approximate the Go
- // 1.13 fmt.Errorf message.
- return &noWrapError{fmt.Sprintf("%sw(%s)", percentBangString, msg), nil, Caller(1)}
- }
- frame := Frame{}
- if internal.EnableTrace {
- frame = Caller(1)
- }
- return &wrapError{msg, err, frame}
-}
-
-func errorAt(args []interface{}, i int) error {
- if i < 0 || i >= len(args) {
- return nil
- }
- err, ok := args[i].(error)
- if !ok {
- return nil
- }
- return err
-}
-
-// formatPlusW is used to avoid the vet check that will barf at %w.
-func formatPlusW(s string) string {
- return s
-}
-
-// Return the index of the only %w in format, or -1 if none.
-// Also return a rewritten format string with %w replaced by %v, and
-// false if there is more than one %w.
-// TODO: handle "%[N]w".
-func parsePercentW(format string) (idx int, newFormat string, ok bool) {
- // Loosely copied from golang.org/x/tools/go/analysis/passes/printf/printf.go.
- idx = -1
- ok = true
- n := 0
- sz := 0
- var isW bool
- for i := 0; i < len(format); i += sz {
- if format[i] != '%' {
- sz = 1
- continue
- }
- // "%%" is not a format directive.
- if i+1 < len(format) && format[i+1] == '%' {
- sz = 2
- continue
- }
- sz, isW = parsePrintfVerb(format[i:])
- if isW {
- if idx >= 0 {
- ok = false
- } else {
- idx = n
- }
- // "Replace" the last character, the 'w', with a 'v'.
- p := i + sz - 1
- format = format[:p] + "v" + format[p+1:]
- }
- n++
- }
- return idx, format, ok
-}
-
-// Parse the printf verb starting with a % at s[0].
-// Return how many bytes it occupies and whether the verb is 'w'.
-func parsePrintfVerb(s string) (int, bool) {
- // Assume only that the directive is a sequence of non-letters followed by a single letter.
- sz := 0
- var r rune
- for i := 1; i < len(s); i += sz {
- r, sz = utf8.DecodeRuneInString(s[i:])
- if unicode.IsLetter(r) {
- return i + sz, r == 'w'
- }
- }
- return len(s), false
-}
-
-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
-}
projects / dotfiles / .git / blobdiff