Files
go-mc/nbt/snbt_decode.go
2021-05-25 20:10:57 +08:00

93 lines
1.9 KiB
Go

package nbt
import (
"fmt"
)
type decodeState struct {
data []byte
off int // next read offset in data
opcode int // last read result
scan scanner
}
const phasePanicMsg = "SNBT decoder out of sync - data changing underfoot?"
func (e *Encoder) WriteSNBT(snbt string) error {
d := decodeState{data: []byte(snbt)}
d.scan.reset()
d.scanWhile(scanSkipSpace)
switch d.opcode {
default:
panic(phasePanicMsg)
case scanBeginLiteral:
case scanBeginCompound:
panic("not implemented")
case scanBeginList:
panic("not implemented")
}
return nil
}
func writeLiteral(e *Encoder, d *decodeState) error {
start := d.readIndex()
d.scanNext()
d.scanWhile(scanContinue)
literal := d.data[start:d.readIndex()]
fmt.Printf("%d %d [%d]- %q\n", start, d.off, d.opcode, literal)
switch literal[0] {
case '"', '\'': // TAG_String
str := literal // TODO: Parse string
e.writeTag(TagString, "")
e.writeInt16(int16(len(str)))
e.w.Write(str)
default:
e.w.Write(literal) // TODO: Parse other literal
}
return nil
}
func writeCompound(e *Encoder, d *decodeState) error {
e.writeTag(TagCompound, "")
return nil
}
// readIndex returns the position of the last byte read.
func (d *decodeState) readIndex() int {
return d.off - 1
}
// scanNext processes the byte at d.data[d.off].
func (d *decodeState) scanNext() {
if d.off < len(d.data) {
d.opcode = d.scan.step(d.data[d.off])
d.off++
} else {
//d.opcode = d.scan.eof()
d.off = len(d.data) + 1 // mark processed EOF with len+1
}
}
// scanWhile processes bytes in d.data[d.off:] until it
// receives a scan code not equal to op.
func (d *decodeState) scanWhile(op int) {
s, data, i := &d.scan, d.data, d.off
for i < len(data) {
newOp := s.step(data[i])
i++
if newOp != op {
d.opcode = newOp
d.off = i
return
}
}
d.off = len(data) + 1 // mark processed EOF with len+1
d.opcode = d.scan.eof()
}