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stack.go
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stack.go
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package emperror
import (
"fmt"
"io"
"github.com/pkg/errors"
)
type stackTracer interface {
StackTrace() errors.StackTrace
}
// StackTrace returns the stack trace from an error (if any).
func StackTrace(err error) (errors.StackTrace, bool) {
st, ok := getStackTracer(err)
if ok {
return st.StackTrace(), true
}
return nil, false
}
// getStackTracer returns the stack trace from an error (if any).
func getStackTracer(err error) (stackTracer, bool) {
var st stackTracer
ForEachCause(err, func(err error) bool {
if s, ok := err.(stackTracer); ok {
st = s
return false
}
return true
})
return st, st != nil
}
type withStack struct {
err error
st stackTracer
}
func (w *withStack) Error() string {
return w.err.Error()
}
func (w *withStack) Cause() error {
return w.err
}
func (w *withStack) StackTrace() errors.StackTrace {
return w.st.StackTrace()
}
// Format implements the fmt.Formatter interface.
func (w *withStack) Format(s fmt.State, verb rune) {
switch verb {
case 'v':
if s.Flag('+') {
_, _ = fmt.Fprintf(s, "%+v", w.Cause())
return
}
fallthrough
case 's':
_, _ = io.WriteString(s, w.Error())
case 'q':
_, _ = fmt.Fprintf(s, "%q", w.Error())
}
}
// ExposeStackTrace exposes the stack trace (if any) in the outer error.
func ExposeStackTrace(err error) error {
if err == nil {
return err
}
st, ok := getStackTracer(err)
if !ok {
return err
}
return &withStack{
err: err,
st: st,
}
}