Function ExtensionDescs

proto/extensions.go:279–316

ExtensionDescs returns a list of extension descriptors found in m, containing descriptors for both populated extension fields in m and also unknown fields of m that are in the extension range. For the later case, an type incomplete descriptor is provided where only the ExtensionDesc.Field field is p

(m Message)

// the ExtensionDesc.Field field is populated.
// The order of the extension descriptors is undefined.
func ExtensionDescs(m Message) ([]*ExtensionDesc, error) {
	mr := MessageReflect(m)
	if mr == nil || !mr.IsValid() || mr.Descriptor().ExtensionRanges().Len() == 0 {
		return nil, errNotExtendable
	}

	// Collect a set of known extension descriptors.
	extDescs := make(map[protoreflect.FieldNumber]*ExtensionDesc)
	mr.Range(func(fd protoreflect.FieldDescriptor, v protoreflect.Value) bool {
		if fd.IsExtension() {
			xt := fd.(protoreflect.ExtensionTypeDescriptor)
			if xd, ok := xt.Type().(*ExtensionDesc); ok {
				extDescs[fd.Number()] = xd
			}
		}
		return true
	})

	// Collect a set of unknown extension descriptors.
	extRanges := mr.Descriptor().ExtensionRanges()
	for b := mr.GetUnknown(); len(b) > 0; {
		num, _, n := protowire.ConsumeField(b)
		if extRanges.Has(num) && extDescs[num] == nil {
			extDescs[num] = nil
		}
		b = b[n:]
	}

	// Transpose the set of descriptors into a list.
	var xts []*ExtensionDesc
	for num, xt := range extDescs {
		if xt == nil {
			xt = &ExtensionDesc{Field: int32(num)}
		}
		xts = append(xts, xt)
	}
	return xts, nil
}

// isValidExtension reports whether xtd is a valid extension descriptor for md.
func isValidExtension(md protoreflect.MessageDescriptor, xtd protoreflect.ExtensionTypeDescriptor) bool {