diff options
Diffstat (limited to 'vendor/github.com/go-errors/errors/error.go')
-rw-r--r-- | vendor/github.com/go-errors/errors/error.go | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/vendor/github.com/go-errors/errors/error.go b/vendor/github.com/go-errors/errors/error.go new file mode 100644 index 00000000..60062a43 --- /dev/null +++ b/vendor/github.com/go-errors/errors/error.go @@ -0,0 +1,217 @@ +// Package errors provides errors that have stack-traces. +// +// This is particularly useful when you want to understand the +// state of execution when an error was returned unexpectedly. +// +// It provides the type *Error which implements the standard +// golang error interface, so you can use this library interchangably +// with code that is expecting a normal error return. +// +// For example: +// +// package crashy +// +// import "github.com/go-errors/errors" +// +// var Crashed = errors.Errorf("oh dear") +// +// func Crash() error { +// return errors.New(Crashed) +// } +// +// This can be called as follows: +// +// package main +// +// import ( +// "crashy" +// "fmt" +// "github.com/go-errors/errors" +// ) +// +// func main() { +// err := crashy.Crash() +// if err != nil { +// if errors.Is(err, crashy.Crashed) { +// fmt.Println(err.(*errors.Error).ErrorStack()) +// } else { +// panic(err) +// } +// } +// } +// +// This package was original written to allow reporting to Bugsnag, +// but after I found similar packages by Facebook and Dropbox, it +// was moved to one canonical location so everyone can benefit. +package errors + +import ( + "bytes" + "fmt" + "reflect" + "runtime" +) + +// The maximum number of stackframes on any error. +var MaxStackDepth = 50 + +// Error is an error with an attached stacktrace. It can be used +// wherever the builtin error interface is expected. +type Error struct { + Err error + stack []uintptr + frames []StackFrame + prefix string +} + +// New makes an Error from the given value. If that value is already an +// error then it will be used directly, if not, it will be passed to +// fmt.Errorf("%v"). The stacktrace will point to the line of code that +// called New. +func New(e interface{}) *Error { + var err error + + switch e := e.(type) { + case error: + err = e + default: + err = fmt.Errorf("%v", e) + } + + stack := make([]uintptr, MaxStackDepth) + length := runtime.Callers(2, stack[:]) + return &Error{ + Err: err, + stack: stack[:length], + } +} + +// Wrap makes an Error from the given value. If that value is already an +// error then it will be used directly, if not, it will be passed to +// fmt.Errorf("%v"). The skip parameter indicates how far up the stack +// to start the stacktrace. 0 is from the current call, 1 from its caller, etc. +func Wrap(e interface{}, skip int) *Error { + var err error + + switch e := e.(type) { + case *Error: + return e + case error: + err = e + default: + err = fmt.Errorf("%v", e) + } + + stack := make([]uintptr, MaxStackDepth) + length := runtime.Callers(2+skip, stack[:]) + return &Error{ + Err: err, + stack: stack[:length], + } +} + +// WrapPrefix makes an Error from the given value. If that value is already an +// error then it will be used directly, if not, it will be passed to +// fmt.Errorf("%v"). The prefix parameter is used to add a prefix to the +// error message when calling Error(). The skip parameter indicates how far +// up the stack to start the stacktrace. 0 is from the current call, +// 1 from its caller, etc. +func WrapPrefix(e interface{}, prefix string, skip int) *Error { + + err := Wrap(e, 1+skip) + + if err.prefix != "" { + prefix = fmt.Sprintf("%s: %s", prefix, err.prefix) + } + + return &Error{ + Err: err.Err, + stack: err.stack, + prefix: prefix, + } + +} + +// Is detects whether the error is equal to a given error. Errors +// are considered equal by this function if they are the same object, +// or if they both contain the same error inside an errors.Error. +func Is(e error, original error) bool { + + if e == original { + return true + } + + if e, ok := e.(*Error); ok { + return Is(e.Err, original) + } + + if original, ok := original.(*Error); ok { + return Is(e, original.Err) + } + + return false +} + +// Errorf creates a new error with the given message. You can use it +// as a drop-in replacement for fmt.Errorf() to provide descriptive +// errors in return values. +func Errorf(format string, a ...interface{}) *Error { + return Wrap(fmt.Errorf(format, a...), 1) +} + +// Error returns the underlying error's message. +func (err *Error) Error() string { + + msg := err.Err.Error() + if err.prefix != "" { + msg = fmt.Sprintf("%s: %s", err.prefix, msg) + } + + return msg +} + +// Stack returns the callstack formatted the same way that go does +// in runtime/debug.Stack() +func (err *Error) Stack() []byte { + buf := bytes.Buffer{} + + for _, frame := range err.StackFrames() { + buf.WriteString(frame.String()) + } + + return buf.Bytes() +} + +// Callers satisfies the bugsnag ErrorWithCallerS() interface +// so that the stack can be read out. +func (err *Error) Callers() []uintptr { + return err.stack +} + +// ErrorStack returns a string that contains both the +// error message and the callstack. +func (err *Error) ErrorStack() string { + return err.TypeName() + " " + err.Error() + "\n" + string(err.Stack()) +} + +// StackFrames returns an array of frames containing information about the +// stack. +func (err *Error) StackFrames() []StackFrame { + if err.frames == nil { + err.frames = make([]StackFrame, len(err.stack)) + + for i, pc := range err.stack { + err.frames[i] = NewStackFrame(pc) + } + } + + return err.frames +} + +// TypeName returns the type this error. e.g. *errors.stringError. +func (err *Error) TypeName() string { + if _, ok := err.Err.(uncaughtPanic); ok { + return "panic" + } + return reflect.TypeOf(err.Err).String() +} |