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// Copyright 2016, Joe Tsai. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE.md file.
// Package errors implements functions to manipulate compression errors.
//
// In idiomatic Go, it is an anti-pattern to use panics as a form of error
// reporting in the API. Instead, the expected way to transmit errors is by
// returning an error value. Unfortunately, the checking of "err != nil" in
// tight loops commonly found in compression causes non-negligible performance
// degradation. While this may not be idiomatic, the internal packages of this
// repository rely on panics as a normal means to convey errors. In order to
// ensure that these panics do not leak across the public API, the public
// packages must recover from these panics and present an error value.
//
// The Panic and Recover functions in this package provide a safe way to
// recover from errors only generated from within this repository.
//
// Example usage:
//
// func Foo() (err error) {
// defer errors.Recover(&err)
//
// if rand.Intn(2) == 0 {
// // Unexpected panics will not be caught by Recover.
// io.Closer(nil).Close()
// } else {
// // Errors thrown by Panic will be caught by Recover.
// errors.Panic(errors.New("whoopsie"))
// }
// }
package errors
import "strings"
const (
// Unknown indicates that there is no classification for this error.
Unknown = iota
// Internal indicates that this error is due to an internal bug.
// Users should file a issue report if this type of error is encountered.
Internal
// Invalid indicates that this error is due to the user misusing the API
// and is indicative of a bug on the user's part.
Invalid
// Deprecated indicates the use of a deprecated and unsupported feature.
Deprecated
// Corrupted indicates that the input stream is corrupted.
Corrupted
// Closed indicates that the handlers are closed.
Closed
)
var codeMap = map[int]string{
Unknown: "unknown error",
Internal: "internal error",
Invalid: "invalid argument",
Deprecated: "deprecated format",
Corrupted: "corrupted input",
Closed: "closed handler",
}
type Error struct {
Code int // The error type
Pkg string // Name of the package where the error originated
Msg string // Descriptive message about the error (optional)
}
func (e Error) Error() string {
var ss []string
for _, s := range []string{e.Pkg, codeMap[e.Code], e.Msg} {
if s != "" {
ss = append(ss, s)
}
}
return strings.Join(ss, ": ")
}
func (e Error) CompressError() {}
func (e Error) IsInternal() bool { return e.Code == Internal }
func (e Error) IsInvalid() bool { return e.Code == Invalid }
func (e Error) IsDeprecated() bool { return e.Code == Deprecated }
func (e Error) IsCorrupted() bool { return e.Code == Corrupted }
func (e Error) IsClosed() bool { return e.Code == Closed }
func IsInternal(err error) bool { return isCode(err, Internal) }
func IsInvalid(err error) bool { return isCode(err, Invalid) }
func IsDeprecated(err error) bool { return isCode(err, Deprecated) }
func IsCorrupted(err error) bool { return isCode(err, Corrupted) }
func IsClosed(err error) bool { return isCode(err, Closed) }
func isCode(err error, code int) bool {
if cerr, ok := err.(Error); ok && cerr.Code == code {
return true
}
return false
}
// errWrap is used by Panic and Recover to ensure that only errors raised by
// Panic are recovered by Recover.
type errWrap struct{ e *error }
func Recover(err *error) {
switch ex := recover().(type) {
case nil:
// Do nothing.
case errWrap:
*err = *ex.e
default:
panic(ex)
}
}
func Panic(err error) {
panic(errWrap{&err})
}
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