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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 fmt
import (
"errors"
"sort"
)
// Errorf formats according to a format specifier and returns the string as a
// value that satisfies error.
//
// If the format specifier includes a %w verb with an error operand,
// the returned error will implement an Unwrap method returning the operand.
// If there is more than one %w verb, the returned error will implement an
// Unwrap method returning a []error containing all the %w operands in the
// order they appear in the arguments.
// It is invalid to supply the %w verb with an operand that does not implement
// the error interface. The %w verb is otherwise a synonym for %v.
func Errorf(format string, a ...any) error {
p := newPrinter()
p.wrapErrs = true
p.doPrintf(format, a)
s := string(p.buf)
var err error
switch len(p.wrappedErrs) {
case 0:
err = errors.New(s)
case 1:
w := &wrapError{msg: s}
w.err, _ = a[p.wrappedErrs[0]].(error)
err = w
default:
if p.reordered {
sort.Ints(p.wrappedErrs)
}
var errs []error
for i, argNum := range p.wrappedErrs {
if i > 0 && p.wrappedErrs[i-1] == argNum {
continue
}
if e, ok := a[argNum].(error); ok {
errs = append(errs, e)
}
}
err = &wrapErrors{s, errs}
}
p.free()
return err
}
type wrapError struct {
msg string
err error
}
func (e *wrapError) Error() string {
return e.msg
}
func (e *wrapError) Unwrap() error {
return e.err
}
type wrapErrors struct {
msg string
errs []error
}
func (e *wrapErrors) Error() string {
return e.msg
}
func (e *wrapErrors) Unwrap() []error {
return e.errs
}
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