Adding the challenge 0204

0204/cell.go

@@ -0,0 +1,57 @@
+package db0204
+
+import (
+	"encoding/binary"
+	"errors"
+	"slices"
+)
+
+type CellType uint8
+
+const (
+	TypeI64 CellType = 1
+	TypeStr CellType = 2
+)
+
+type Cell struct {
+	Type CellType
+	I64  int64
+	Str  []byte
+}
+
+func (cell *Cell) Encode(toAppend []byte) []byte {
+	switch cell.Type {
+	case TypeI64:
+		return binary.LittleEndian.AppendUint64(toAppend, uint64(cell.I64))
+	case TypeStr:
+		toAppend = binary.LittleEndian.AppendUint32(toAppend, uint32(len(cell.Str)))
+		return append(toAppend, cell.Str...)
+	default:
+		panic("unreachable")
+	}
+}
+
+func (cell *Cell) Decode(data []byte) (rest []byte, err error) {
+	switch cell.Type {
+	case TypeI64:
+		if len(data) < 8 {
+			return data, errors.New("expect more data")
+		}
+		cell.I64 = int64(binary.LittleEndian.Uint64(data[0:8]))
+		return data[8:], nil
+	case TypeStr:
+		if len(data) < 4 {
+			return data, errors.New("expect more data")
+		}
+		size := int(binary.LittleEndian.Uint32(data[0:4]))
+		if len(data) < 4+size {
+			return data, errors.New("expect more data")
+		}
+		cell.Str = slices.Clone(data[4 : 4+size])
+		return data[4+size:], nil
+	default:
+		panic("unreachable")
+	}
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/