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package struc
import (
"encoding/binary"
"fmt"
"io"
"reflect"
"strings"
)
type Fields []*Field
func (f Fields) SetByteOrder(order binary.ByteOrder) {
for _, field := range f {
if field != nil {
field.Order = order
}
}
}
func (f Fields) String() string {
fields := make([]string, len(f))
for i, field := range f {
if field != nil {
fields[i] = field.String()
}
}
return "{" + strings.Join(fields, ", ") + "}"
}
func (f Fields) Sizeof(val reflect.Value, options *Options) int {
for val.Kind() == reflect.Ptr {
val = val.Elem()
}
size := 0
for i, field := range f {
if field != nil {
size += field.Size(val.Field(i), options)
}
}
return size
}
func (f Fields) sizefrom(val reflect.Value, index []int) int {
field := val.FieldByIndex(index)
switch field.Kind() {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
return int(field.Int())
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
n := int(field.Uint())
// all the builtin array length types are native int
// so this guards against weird truncation
if n < 0 {
return 0
}
return n
default:
name := val.Type().FieldByIndex(index).Name
panic(fmt.Sprintf("sizeof field %T.%s not an integer type", val.Interface(), name))
}
}
func (f Fields) Pack(buf []byte, val reflect.Value, options *Options) (int, error) {
for val.Kind() == reflect.Ptr {
val = val.Elem()
}
pos := 0
for i, field := range f {
if field == nil {
continue
}
v := val.Field(i)
length := field.Len
if field.Sizefrom != nil {
length = f.sizefrom(val, field.Sizefrom)
}
if length <= 0 && field.Slice {
length = v.Len()
}
if field.Sizeof != nil {
length := val.FieldByIndex(field.Sizeof).Len()
switch field.kind {
case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
// allocating a new int here has fewer side effects (doesn't update the original struct)
// but it's a wasteful allocation
// the old method might work if we just cast the temporary int/uint to the target type
v = reflect.New(v.Type()).Elem()
v.SetInt(int64(length))
case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
v = reflect.New(v.Type()).Elem()
v.SetUint(uint64(length))
default:
panic(fmt.Sprintf("sizeof field is not int or uint type: %s, %s", field.Name, v.Type()))
}
}
if n, err := field.Pack(buf[pos:], v, length, options); err != nil {
return n, err
} else {
pos += n
}
}
return pos, nil
}
func (f Fields) Unpack(r io.Reader, val reflect.Value, options *Options) error {
for val.Kind() == reflect.Ptr {
val = val.Elem()
}
var tmp [8]byte
var buf []byte
for i, field := range f {
if field == nil {
continue
}
v := val.Field(i)
length := field.Len
if field.Sizefrom != nil {
length = f.sizefrom(val, field.Sizefrom)
}
if v.Kind() == reflect.Ptr && !v.Elem().IsValid() {
v.Set(reflect.New(v.Type().Elem()))
}
if field.Type == Struct {
if field.Slice {
vals := reflect.MakeSlice(v.Type(), length, length)
for i := 0; i < length; i++ {
v := vals.Index(i)
fields, err := parseFields(v)
if err != nil {
return err
}
if err := fields.Unpack(r, v, options); err != nil {
return err
}
}
v.Set(vals)
} else {
// TODO: DRY (we repeat the inner loop above)
fields, err := parseFields(v)
if err != nil {
return err
}
if err := fields.Unpack(r, v, options); err != nil {
return err
}
}
continue
} else {
typ := field.Type.Resolve(options)
if typ == CustomType {
if err := v.Addr().Interface().(Custom).Unpack(r, length, options); err != nil {
return err
}
} else {
size := length * field.Type.Resolve(options).Size()
if size < 8 {
buf = tmp[:size]
} else {
buf = make([]byte, size)
}
if _, err := io.ReadFull(r, buf); err != nil {
return err
}
err := field.Unpack(buf[:size], v, length, options)
if err != nil {
return err
}
}
}
}
return nil
}
|
