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package mt
import (
"fmt"
"io"
)
type PointedThing interface {
pt()
}
func (*PointedNode) pt() {}
func (*PointedAO) pt() {}
type PointedNode struct {
Under, Above [3]int16
}
func PointedSameNode(pos [3]int16) PointedThing {
return &PointedNode{pos, pos}
}
type PointedAO struct {
ID AOID
}
func writePointedThing(w io.Writer, pt PointedThing) error {
buf := make([]byte, 2)
buf[0] = 0
switch pt.(type) {
case nil:
buf[1] = 0
case *PointedNode:
buf[1] = 1
case *PointedAO:
buf[1] = 2
default:
panic(pt)
}
if _, err := w.Write(buf); err != nil {
return err
}
if pt == nil {
return nil
}
return serialize(w, pt)
}
func readPointedThing(r io.Reader) (PointedThing, error) {
buf := make([]byte, 2)
if _, err := io.ReadFull(r, buf); err != nil {
return nil, err
}
if buf[0] != 0 {
return nil, fmt.Errorf("unsupported PointedThing version: %d", buf[0])
}
var pt PointedThing
switch buf[1] {
case 0:
return nil, nil
case 1:
pt = new(PointedNode)
case 2:
pt = new(PointedAO)
case 3:
return nil, fmt.Errorf("invalid PointedThing type: %d", buf[1])
}
return pt, deserialize(r, pt)
}
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