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package conv
// stolen from the Go standard library, text/template package.
import (
"fmt"
"reflect"
)
var (
errorType = reflect.TypeOf((*error)(nil)).Elem()
fmtStringerType = reflect.TypeOf((*fmt.Stringer)(nil)).Elem()
)
// printableValue returns the, possibly indirected, interface value inside v that
// is best for a call to formatted printer.
func printableValue(v reflect.Value) (any, bool) {
if v.Kind() == reflect.Ptr {
v, _ = indirect(v) // fmt.Fprint handles nil.
}
if !v.IsValid() {
return "<no value>", true
}
if !v.Type().Implements(errorType) && !v.Type().Implements(fmtStringerType) {
if v.CanAddr() && (reflect.PointerTo(v.Type()).Implements(errorType) || reflect.PointerTo(v.Type()).Implements(fmtStringerType)) {
v = v.Addr()
} else {
switch v.Kind() {
case reflect.Chan, reflect.Func:
return nil, false
}
}
}
return v.Interface(), true
}
// indirect returns the item at the end of indirection, and a bool to indicate if it's nil.
func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
for ; v.Kind() == reflect.Ptr || v.Kind() == reflect.Interface; v = v.Elem() {
if v.IsNil() {
return v, true
}
}
return v, false
}
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