vendor.github.com.pion.rtcp.packet_stringifier.go Maven / Gradle / Ivy
package rtcp
import (
"fmt"
"reflect"
)
/*
Converts an RTCP Packet into a human-readable format. The Packets
themselves can control the presentation as follows:
- Fields of a type that have a String() method will be formatted
with that String method (which should not emit '\n' characters)
- Otherwise, fields with a tag containing a "fmt" string will use that
format when serializing the value. For example, to format an SSRC
value as base 16 insted of base 10:
type ExamplePacket struct {
LocalSSRC uint32 `fmt:"0x%X"`
RemotsSSRCs []uint32 `fmt:"%X"`
}
- If no fmt string is present, "%+v" is used by default
The intention of this stringify() function is to simplify creation
of String() methods on new packet types, as it provides a simple
baseline implementation that works well in the majority of cases.
*/
func stringify(p Packet) string {
value := reflect.Indirect(reflect.ValueOf(p))
return formatField(value.Type().String(), "", p, "")
}
func formatField(name string, format string, f interface{}, indent string) string { //nolint:gocognit
out := indent
value := reflect.ValueOf(f)
if !value.IsValid() {
return fmt.Sprintf("%s%s: \n", out, name)
}
isPacket := reflect.TypeOf(f).Implements(reflect.TypeOf((*Packet)(nil)).Elem())
// Resolve pointers to their underlying values
if value.Type().Kind() == reflect.Ptr && !value.IsNil() {
underlying := reflect.Indirect(value)
if underlying.IsValid() {
value = underlying
}
}
// If the field type has a custom String method, use that
// (unless we're a packet, since we want to avoid recursing
// back into this function if the Packet's String() method
// uses it)
if stringMethod := value.MethodByName("String"); !isPacket && stringMethod.IsValid() {
out += fmt.Sprintf("%s: %s\n", name, stringMethod.Call([]reflect.Value{}))
return out
}
switch value.Kind() {
case reflect.Struct:
out += fmt.Sprintf("%s:\n", name)
for i := 0; i < value.NumField(); i++ {
if value.Field(i).CanInterface() {
format = value.Type().Field(i).Tag.Get("fmt")
if format == "" {
format = "%+v"
}
out += formatField(value.Type().Field(i).Name, format, value.Field(i).Interface(), indent+"\t")
}
}
case reflect.Slice:
childKind := value.Type().Elem().Kind()
_, hasStringMethod := value.Type().Elem().MethodByName("String")
if hasStringMethod || childKind == reflect.Struct || childKind == reflect.Ptr || childKind == reflect.Interface || childKind == reflect.Slice {
out += fmt.Sprintf("%s:\n", name)
for i := 0; i < value.Len(); i++ {
childName := fmt.Sprint(i)
// Since interfaces can hold different types of things, we add the
// most specific type name to the name to make it clear what the
// subsequent fields represent.
if value.Index(i).Kind() == reflect.Interface {
childName += fmt.Sprintf(" (%s)", reflect.Indirect(reflect.ValueOf(value.Index(i).Interface())).Type())
}
if value.Index(i).CanInterface() {
out += formatField(childName, format, value.Index(i).Interface(), indent+"\t")
}
}
return out
}
// If we didn't take care of stringing the value already, we fall through to the
// generic case. This will print slices of basic types on a single line.
fallthrough
default:
if value.CanInterface() {
out += fmt.Sprintf("%s: "+format+"\n", name, value.Interface())
}
}
return out
}