Adopt more fixed size array types for struct fields

[rbdr/mobius] / hotline / field.go

diff --git a/hotline/field.go b/hotline/field.go
index c205c42b8f2eb5eb43eb45e7d8714ab0c493e920..2fcb41a1a5451e070ba187fe17695af4d3f90171 100644 (file)
--- a/hotline/field.go
+++ b/hotline/field.go
@@ -2,6 +2,7 @@ package hotline
 
 import (
        "encoding/binary"
+       "io"
        "slices"
 )
 
@@ -66,9 +67,11 @@ const (
 )
 
 type Field struct {
-       ID        []byte // Type of field
-       FieldSize []byte // Size of the data part
-       Data      []byte // Actual field content
+       ID        [2]byte // Type of field
+       FieldSize [2]byte // Size of the data part
+       Data      []byte  // Actual field content
+
+       readOffset int // Internal offset to track read progress
 }
 
 type requiredField struct {
@@ -77,26 +80,56 @@ type requiredField struct {
 }
 
 func NewField(id uint16, data []byte) Field {
-       idBytes := make([]byte, 2)
-       binary.BigEndian.PutUint16(idBytes, id)
+       f := Field{Data: data}
+       binary.BigEndian.PutUint16(f.ID[:], id)
+       binary.BigEndian.PutUint16(f.FieldSize[:], uint16(len(data)))
+
+       return f
+}
 
-       bs := make([]byte, 2)
-       binary.BigEndian.PutUint16(bs, uint16(len(data)))
+// fieldScanner implements bufio.SplitFunc for parsing byte slices into complete tokens
+func fieldScanner(data []byte, _ bool) (advance int, token []byte, err error) {
+       if len(data) < minFieldLen {
+               return 0, nil, nil
+       }
 
-       return Field{
-               ID:        idBytes,
-               FieldSize: bs,
-               Data:      data,
+       // tranLen represents the length of bytes that are part of the transaction
+       neededSize := minFieldLen + int(binary.BigEndian.Uint16(data[2:4]))
+       if neededSize > len(data) {
+               return 0, nil, nil
        }
+
+       return neededSize, data[0:neededSize], nil
 }
 
-func (f Field) Payload() []byte {
-       return slices.Concat(f.ID, f.FieldSize, f.Data)
+// Read implements io.Reader for Field
+func (f *Field) Read(p []byte) (int, error) {
+       buf := slices.Concat(f.ID[:], f.FieldSize[:], f.Data)
+
+       if f.readOffset >= len(buf) {
+               return 0, io.EOF // All bytes have been read
+       }
+
+       n := copy(p, buf[f.readOffset:])
+       f.readOffset += n
+
+       return n, nil
+}
+
+// Write implements io.Writer for Field
+func (f *Field) Write(p []byte) (int, error) {
+       f.ID = [2]byte(p[0:2])
+       f.FieldSize = [2]byte(p[2:4])
+
+       i := int(binary.BigEndian.Uint16(f.FieldSize[:]))
+       f.Data = p[4 : 4+i]
+
+       return minFieldLen + i, nil
 }
 
 func getField(id int, fields *[]Field) *Field {
        for _, field := range *fields {
-               if id == int(binary.BigEndian.Uint16(field.ID)) {
+               if id == int(binary.BigEndian.Uint16(field.ID[:])) {
                        return &field
                }
        }