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package webrtc
import (
"encoding/json"
"strings"
)
// SDPType describes the type of an SessionDescription.
type SDPType int
const (
// SDPTypeOffer indicates that a description MUST be treated as an SDP
// offer.
SDPTypeOffer SDPType = iota + 1
// SDPTypePranswer indicates that a description MUST be treated as an
// SDP answer, but not a final answer. A description used as an SDP
// pranswer may be applied as a response to an SDP offer, or an update to
// a previously sent SDP pranswer.
SDPTypePranswer
// SDPTypeAnswer indicates that a description MUST be treated as an SDP
// final answer, and the offer-answer exchange MUST be considered complete.
// A description used as an SDP answer may be applied as a response to an
// SDP offer or as an update to a previously sent SDP pranswer.
SDPTypeAnswer
// SDPTypeRollback indicates that a description MUST be treated as
// canceling the current SDP negotiation and moving the SDP offer and
// answer back to what it was in the previous stable state. Note the
// local or remote SDP descriptions in the previous stable state could be
// null if there has not yet been a successful offer-answer negotiation.
SDPTypeRollback
)
// This is done this way because of a linter.
const (
sdpTypeOfferStr = "offer"
sdpTypePranswerStr = "pranswer"
sdpTypeAnswerStr = "answer"
sdpTypeRollbackStr = "rollback"
)
// NewSDPType creates an SDPType from a string
func NewSDPType(raw string) SDPType {
switch raw {
case sdpTypeOfferStr:
return SDPTypeOffer
case sdpTypePranswerStr:
return SDPTypePranswer
case sdpTypeAnswerStr:
return SDPTypeAnswer
case sdpTypeRollbackStr:
return SDPTypeRollback
default:
return SDPType(Unknown)
}
}
func (t SDPType) String() string {
switch t {
case SDPTypeOffer:
return sdpTypeOfferStr
case SDPTypePranswer:
return sdpTypePranswerStr
case SDPTypeAnswer:
return sdpTypeAnswerStr
case SDPTypeRollback:
return sdpTypeRollbackStr
default:
return ErrUnknownType.Error()
}
}
// MarshalJSON enables JSON marshaling of a SDPType
func (t SDPType) MarshalJSON() ([]byte, error) {
return json.Marshal(t.String())
}
// UnmarshalJSON enables JSON unmarshaling of a SDPType
func (t *SDPType) UnmarshalJSON(b []byte) error {
var s string
if err := json.Unmarshal(b, &s); err != nil {
return err
}
switch strings.ToLower(s) {
default:
return ErrUnknownType
case "offer":
*t = SDPTypeOffer
case "pranswer":
*t = SDPTypePranswer
case "answer":
*t = SDPTypeAnswer
case "rollback":
*t = SDPTypeRollback
}
return nil
}
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