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chain.go
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chain.go
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package throw
import (
"errors"
"reflect"
"strings"
)
type DeepestStackMode uint8
const (
_ DeepestStackMode = iota
InheritedTrace
SupersededTrace
)
type StackTraceHolder interface {
// Cause returns a cause for this stack trace. It can NOT be used like Unwrap() as it may return self.
Cause() error
// ShallowStackTrace returns a stack trace registered for this cause
ShallowStackTrace() StackTrace
// DeepestStackTrace returns this or the deepest stack trace from cause's error chain that embeds ShallowStackTrace.
// Bool value is true when the stack trace was inherited from the cause.
DeepestStackTrace() (StackTrace, DeepestStackMode)
}
// StackOf returns a target-matched entry with a wrapping StackTraceHolder (optional)
// When (target) is nil - returns the last error of the chain
// nolint
func StackOf(errChain, target error) (error, StackTraceHolder, bool) {
isComparable := target == nil || reflect.TypeOf(target).Comparable()
for errChain != nil {
nextErr := errors.Unwrap(errChain)
if sw, ok := errChain.(StackTraceHolder); ok {
if target == nil && nextErr == nil || isThis(isComparable, sw.Cause(), target) {
return errChain, sw, true
}
} else if target == nil && nextErr == nil || isThis(isComparable, errChain, target) {
return errChain, nil, true
}
errChain = nextErr
}
return nil, nil, false
}
// NearestStackOf returns a target-matched entry with a last encountered StackTraceHolder with a either shallow or deep non-nil stack (optional)
// When (target) is nil - returns the last error of the chain
// When (target) is not found, returns only the last StackTraceHolder.
// nolint
func NearestStackOf(errChain, target error) (error, StackTraceHolder, bool) {
isComparable := target == nil || reflect.TypeOf(target).Comparable()
var sth StackTraceHolder
for errChain != nil {
nextErr := errors.Unwrap(errChain)
if sw, ok := errChain.(StackTraceHolder); ok {
if st, _ := sw.DeepestStackTrace(); st != nil {
sth = sw
}
if target == nil && nextErr == nil || isThis(isComparable, sw.Cause(), target) {
return errChain, sth, true
}
} else if target == nil && nextErr == nil || isThis(isComparable, errChain, target) {
return errChain, sth, true
}
errChain = nextErr
}
return nil, sth, false
}
func DeepestStackTraceOf(errChain error) StackTrace {
for errChain != nil {
if sw, ok := errChain.(StackTraceHolder); ok {
if st, _ := sw.DeepestStackTrace(); st != nil {
return st
}
}
errChain = errors.Unwrap(errChain)
}
return nil
}
func ErrorWithStack(errChain error) string {
return JoinStackText(errChain.Error(), DeepestStackTraceOf(errChain))
}
func ErrorWithTopOrFullStack(errChain error) (string, StackTrace) {
st := DeepestStackTraceOf(errChain)
if st == nil || st.IsFullStack() {
return errChain.Error(), st
}
return JoinStackText(errChain.Error(), st), nil
}
func ErrorWithTopOrMinimizedStack(errChain error, boundPackage string, includeBoundary bool) (string, StackTrace) {
st := DeepestStackTraceOf(errChain)
switch {
case st == nil:
return errChain.Error(), nil
case !st.IsFullStack():
return JoinStackText(errChain.Error(), st), nil
}
if boundPackage != "" {
st = MinimizeStackTrace(st, boundPackage, includeBoundary)
}
min := ExtractStackTop(st, 0)
return JoinStackText(errChain.Error(), min), st
}
// OutermostStack returns the closest StackTraceHolder with non-nil ShallowStackTrace from errChain
func OutermostStack(errChain error) StackTraceHolder {
for errChain != nil {
if sw, ok := errChain.(StackTraceHolder); ok && sw.ShallowStackTrace() != nil {
return sw
}
errChain = errors.Unwrap(errChain)
}
return nil
}
// InnermostStack returns the most distant StackTraceHolder with non-nil ShallowStackTrace from errChain
func InnermostStack(errChain error) (sth StackTraceHolder) {
for errChain != nil {
if sw, ok := errChain.(StackTraceHolder); ok && sw.ShallowStackTrace() != nil {
sth = sw
}
errChain = errors.Unwrap(errChain)
}
return
}
// InnermostFullStack returns the most distant StackTraceHolder with non-nil ShallowStackTrace and IsFullStack from errChain
func InnermostFullStack(errChain error) (sth StackTraceHolder) {
for errChain != nil {
if sw, ok := errChain.(StackTraceHolder); ok && sw.ShallowStackTrace() != nil && sw.ShallowStackTrace().IsFullStack() {
sth = sw
}
errChain = errors.Unwrap(errChain)
}
return
}
// Walks through the given error chain and call (fn) for each entry, does unwrapping for stack trace data.
func Walk(errChain error, fn func(error, StackTraceHolder) bool) bool {
if fn == nil {
panic(IllegalValue())
}
for errChain != nil {
if sw, ok := errChain.(StackTraceHolder); ok {
if fn(sw.Cause(), sw) {
return true
}
errChain = errors.Unwrap(errChain)
} else if fn(errChain, nil) {
return true
}
errChain = errors.Unwrap(errChain)
}
return false
}
// PrintTo calls Walk() and builds a full list of errors and corresponding stacks in the chain.
func PrintTo(errChain error, includeStack bool, b *strings.Builder) {
Walk(errChain, func(err error, traceHolder StackTraceHolder) bool {
var trace StackTrace
if traceHolder != nil {
trace = traceHolder.ShallowStackTrace()
}
switch {
case err != nil:
b.WriteString(err.Error())
b.WriteByte('\n')
if trace == nil || !includeStack {
return false
}
b.WriteString(stackTracePrintPrefix)
case trace != nil && includeStack:
b.WriteString("<nil>\n" + stackTracePrintPrefix)
default:
b.WriteString("<nil>\n")
return false
}
if err := trace.WriteStackTraceTo(b); err != nil {
panic(err)
}
b.WriteByte('\n')
return false
})
}
// Print is a convenience wrapper for PrintTo()
func Print(errChain error) string {
if errChain == nil {
return ""
}
b := strings.Builder{}
PrintTo(errChain, true, &b)
return b.String()
}
// IsEqual does panic-safe comparison of error values. Incomparable values will always return false.
// It uses Is() on both sides
func IsEqual(err0, err1 error) bool {
if err0 == nil || err1 == nil {
return err0 == err1
}
if reflect.TypeOf(err1).Comparable() && err0 == err1 {
return true
}
if x, ok := err0.(interface{ Is(error) bool }); ok && x.Is(err1) {
return true
}
if x, ok := err1.(interface{ Is(error) bool }); ok && x.Is(err0) {
return true
}
return false
}
type iser interface {
Is(error) bool
}
func isThis(isComparable bool, err, target error) bool {
if isComparable && err == target {
return true
}
if x, ok := err.(iser); ok && x.Is(target) {
return true
}
return false
}