gtsocial-umbx

encode.go (41222B)

---

 // Copyright (c) 2012-2020 Ugorji Nwoke. All rights reserved.
 // Use of this source code is governed by a MIT license found in the LICENSE file.
 
 package codec
 
 import (
 	"encoding"
 	"errors"
 	"io"
 	"reflect"
 	"sort"
 	"strconv"
 	"time"
 )
 
 // defEncByteBufSize is the default size of []byte used
 // for bufio buffer or []byte (when nil passed)
 const defEncByteBufSize = 1 << 10 // 4:16, 6:64, 8:256, 10:1024
 
 var errEncoderNotInitialized = errors.New("Encoder not initialized")
 
 // encDriver abstracts the actual codec (binc vs msgpack, etc)
 type encDriver interface {
 	EncodeNil()
 	EncodeInt(i int64)
 	EncodeUint(i uint64)
 	EncodeBool(b bool)
 	EncodeFloat32(f float32)
 	EncodeFloat64(f float64)
 	EncodeRawExt(re *RawExt)
 	EncodeExt(v interface{}, basetype reflect.Type, xtag uint64, ext Ext)
 	// EncodeString using cUTF8, honor'ing StringToRaw flag
 	EncodeString(v string)
 	EncodeStringBytesRaw(v []byte)
 	EncodeTime(time.Time)
 	WriteArrayStart(length int)
 	WriteArrayEnd()
 	WriteMapStart(length int)
 	WriteMapEnd()
 
 	// reset will reset current encoding runtime state, and cached information from the handle
 	reset()
 
 	encoder() *Encoder
 
 	driverStateManager
 }
 
 type encDriverContainerTracker interface {
 	WriteArrayElem()
 	WriteMapElemKey()
 	WriteMapElemValue()
 }
 
 type encDriverNoState struct{}
 
 func (encDriverNoState) captureState() interface{}  { return nil }
 func (encDriverNoState) reset()                     {}
 func (encDriverNoState) resetState()                {}
 func (encDriverNoState) restoreState(v interface{}) {}
 
 type encDriverNoopContainerWriter struct{}
 
 func (encDriverNoopContainerWriter) WriteArrayStart(length int) {}
 func (encDriverNoopContainerWriter) WriteArrayEnd()             {}
 func (encDriverNoopContainerWriter) WriteMapStart(length int)   {}
 func (encDriverNoopContainerWriter) WriteMapEnd()               {}
 
 // encStructFieldObj[Slice] is used for sorting when there are missing fields and canonical flag is set
 type encStructFieldObj struct {
 	key   string
 	rv    reflect.Value
 	intf  interface{}
 	ascii bool
 	isRv  bool
 }
 
 type encStructFieldObjSlice []encStructFieldObj
 
 func (p encStructFieldObjSlice) Len() int      { return len(p) }
 func (p encStructFieldObjSlice) Swap(i, j int) { p[uint(i)], p[uint(j)] = p[uint(j)], p[uint(i)] }
 func (p encStructFieldObjSlice) Less(i, j int) bool {
 	return p[uint(i)].key < p[uint(j)].key
 }
 
 // EncodeOptions captures configuration options during encode.
 type EncodeOptions struct {
 	// WriterBufferSize is the size of the buffer used when writing.
 	//
 	// if > 0, we use a smart buffer internally for performance purposes.
 	WriterBufferSize int
 
 	// ChanRecvTimeout is the timeout used when selecting from a chan.
 	//
 	// Configuring this controls how we receive from a chan during the encoding process.
 	//   - If ==0, we only consume the elements currently available in the chan.
 	//   - if  <0, we consume until the chan is closed.
 	//   - If  >0, we consume until this timeout.
 	ChanRecvTimeout time.Duration
 
 	// StructToArray specifies to encode a struct as an array, and not as a map
 	StructToArray bool
 
 	// Canonical representation means that encoding a value will always result in the same
 	// sequence of bytes.
 	//
 	// This only affects maps, as the iteration order for maps is random.
 	//
 	// The implementation MAY use the natural sort order for the map keys if possible:
 	//
 	//     - If there is a natural sort order (ie for number, bool, string or []byte keys),
 	//       then the map keys are first sorted in natural order and then written
 	//       with corresponding map values to the strema.
 	//     - If there is no natural sort order, then the map keys will first be
 	//       encoded into []byte, and then sorted,
 	//       before writing the sorted keys and the corresponding map values to the stream.
 	//
 	Canonical bool
 
 	// CheckCircularRef controls whether we check for circular references
 	// and error fast during an encode.
 	//
 	// If enabled, an error is received if a pointer to a struct
 	// references itself either directly or through one of its fields (iteratively).
 	//
 	// This is opt-in, as there may be a performance hit to checking circular references.
 	CheckCircularRef bool
 
 	// RecursiveEmptyCheck controls how we determine whether a value is empty.
 	//
 	// If true, we descend into interfaces and pointers to reursively check if value is empty.
 	//
 	// We *might* check struct fields one by one to see if empty
 	// (if we cannot directly check if a struct value is equal to its zero value).
 	// If so, we honor IsZero, Comparable, IsCodecEmpty(), etc.
 	// Note: This *may* make OmitEmpty more expensive due to the large number of reflect calls.
 	//
 	// If false, we check if the value is equal to its zero value (newly allocated state).
 	RecursiveEmptyCheck bool
 
 	// Raw controls whether we encode Raw values.
 	// This is a "dangerous" option and must be explicitly set.
 	// If set, we blindly encode Raw values as-is, without checking
 	// if they are a correct representation of a value in that format.
 	// If unset, we error out.
 	Raw bool
 
 	// StringToRaw controls how strings are encoded.
 	//
 	// As a go string is just an (immutable) sequence of bytes,
 	// it can be encoded either as raw bytes or as a UTF string.
 	//
 	// By default, strings are encoded as UTF-8.
 	// but can be treated as []byte during an encode.
 	//
 	// Note that things which we know (by definition) to be UTF-8
 	// are ALWAYS encoded as UTF-8 strings.
 	// These include encoding.TextMarshaler, time.Format calls, struct field names, etc.
 	StringToRaw bool
 
 	// OptimumSize controls whether we optimize for the smallest size.
 	//
 	// Some formats will use this flag to determine whether to encode
 	// in the smallest size possible, even if it takes slightly longer.
 	//
 	// For example, some formats that support half-floats might check if it is possible
 	// to store a float64 as a half float. Doing this check has a small performance cost,
 	// but the benefit is that the encoded message will be smaller.
 	OptimumSize bool
 
 	// NoAddressableReadonly controls whether we try to force a non-addressable value
 	// to be addressable so we can call a pointer method on it e.g. for types
 	// that support Selfer, json.Marshaler, etc.
 	//
 	// Use it in the very rare occurrence that your types modify a pointer value when calling
 	// an encode callback function e.g. JsonMarshal, TextMarshal, BinaryMarshal or CodecEncodeSelf.
 	NoAddressableReadonly bool
 }
 
 // ---------------------------------------------
 
 func (e *Encoder) rawExt(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeRawExt(rv2i(rv).(*RawExt))
 }
 
 func (e *Encoder) ext(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeExt(rv2i(rv), f.ti.rt, f.xfTag, f.xfFn)
 }
 
 func (e *Encoder) selferMarshal(f *codecFnInfo, rv reflect.Value) {
 	rv2i(rv).(Selfer).CodecEncodeSelf(e)
 }
 
 func (e *Encoder) binaryMarshal(f *codecFnInfo, rv reflect.Value) {
 	bs, fnerr := rv2i(rv).(encoding.BinaryMarshaler).MarshalBinary()
 	e.marshalRaw(bs, fnerr)
 }
 
 func (e *Encoder) textMarshal(f *codecFnInfo, rv reflect.Value) {
 	bs, fnerr := rv2i(rv).(encoding.TextMarshaler).MarshalText()
 	e.marshalUtf8(bs, fnerr)
 }
 
 func (e *Encoder) jsonMarshal(f *codecFnInfo, rv reflect.Value) {
 	bs, fnerr := rv2i(rv).(jsonMarshaler).MarshalJSON()
 	e.marshalAsis(bs, fnerr)
 }
 
 func (e *Encoder) raw(f *codecFnInfo, rv reflect.Value) {
 	e.rawBytes(rv2i(rv).(Raw))
 }
 
 func (e *Encoder) encodeComplex64(v complex64) {
 	if imag(v) != 0 {
 		e.errorf("cannot encode complex number: %v, with imaginary values: %v", v, imag(v))
 	}
 	e.e.EncodeFloat32(real(v))
 }
 
 func (e *Encoder) encodeComplex128(v complex128) {
 	if imag(v) != 0 {
 		e.errorf("cannot encode complex number: %v, with imaginary values: %v", v, imag(v))
 	}
 	e.e.EncodeFloat64(real(v))
 }
 
 func (e *Encoder) kBool(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeBool(rvGetBool(rv))
 }
 
 func (e *Encoder) kTime(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeTime(rvGetTime(rv))
 }
 
 func (e *Encoder) kString(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeString(rvGetString(rv))
 }
 
 func (e *Encoder) kFloat32(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeFloat32(rvGetFloat32(rv))
 }
 
 func (e *Encoder) kFloat64(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeFloat64(rvGetFloat64(rv))
 }
 
 func (e *Encoder) kComplex64(f *codecFnInfo, rv reflect.Value) {
 	e.encodeComplex64(rvGetComplex64(rv))
 }
 
 func (e *Encoder) kComplex128(f *codecFnInfo, rv reflect.Value) {
 	e.encodeComplex128(rvGetComplex128(rv))
 }
 
 func (e *Encoder) kInt(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeInt(int64(rvGetInt(rv)))
 }
 
 func (e *Encoder) kInt8(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeInt(int64(rvGetInt8(rv)))
 }
 
 func (e *Encoder) kInt16(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeInt(int64(rvGetInt16(rv)))
 }
 
 func (e *Encoder) kInt32(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeInt(int64(rvGetInt32(rv)))
 }
 
 func (e *Encoder) kInt64(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeInt(int64(rvGetInt64(rv)))
 }
 
 func (e *Encoder) kUint(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeUint(uint64(rvGetUint(rv)))
 }
 
 func (e *Encoder) kUint8(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeUint(uint64(rvGetUint8(rv)))
 }
 
 func (e *Encoder) kUint16(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeUint(uint64(rvGetUint16(rv)))
 }
 
 func (e *Encoder) kUint32(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeUint(uint64(rvGetUint32(rv)))
 }
 
 func (e *Encoder) kUint64(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeUint(uint64(rvGetUint64(rv)))
 }
 
 func (e *Encoder) kUintptr(f *codecFnInfo, rv reflect.Value) {
 	e.e.EncodeUint(uint64(rvGetUintptr(rv)))
 }
 
 func (e *Encoder) kErr(f *codecFnInfo, rv reflect.Value) {
 	e.errorf("unsupported kind %s, for %#v", rv.Kind(), rv)
 }
 
 func chanToSlice(rv reflect.Value, rtslice reflect.Type, timeout time.Duration) (rvcs reflect.Value) {
 	rvcs = rvZeroK(rtslice, reflect.Slice)
 	if timeout < 0 { // consume until close
 		for {
 			recv, recvOk := rv.Recv()
 			if !recvOk {
 				break
 			}
 			rvcs = reflect.Append(rvcs, recv)
 		}
 	} else {
 		cases := make([]reflect.SelectCase, 2)
 		cases[0] = reflect.SelectCase{Dir: reflect.SelectRecv, Chan: rv}
 		if timeout == 0 {
 			cases[1] = reflect.SelectCase{Dir: reflect.SelectDefault}
 		} else {
 			tt := time.NewTimer(timeout)
 			cases[1] = reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(tt.C)}
 		}
 		for {
 			chosen, recv, recvOk := reflect.Select(cases)
 			if chosen == 1 || !recvOk {
 				break
 			}
 			rvcs = reflect.Append(rvcs, recv)
 		}
 	}
 	return
 }
 
 func (e *Encoder) kSeqFn(rtelem reflect.Type) (fn *codecFn) {
 	for rtelem.Kind() == reflect.Ptr {
 		rtelem = rtelem.Elem()
 	}
 	// if kind is reflect.Interface, do not pre-determine the encoding type,
 	// because preEncodeValue may break it down to a concrete type and kInterface will bomb.
 	if rtelem.Kind() != reflect.Interface {
 		fn = e.h.fn(rtelem)
 	}
 	return
 }
 
 func (e *Encoder) kSliceWMbs(rv reflect.Value, ti *typeInfo) {
 	var l = rvLenSlice(rv)
 	if l == 0 {
 		e.mapStart(0)
 	} else {
 		e.haltOnMbsOddLen(l)
 		e.mapStart(l >> 1) // e.mapStart(l / 2)
 		fn := e.kSeqFn(ti.elem)
 		for j := 0; j < l; j++ {
 			if j&1 == 0 { // j%2 == 0 {
 				e.mapElemKey()
 			} else {
 				e.mapElemValue()
 			}
 			e.encodeValue(rvSliceIndex(rv, j, ti), fn)
 		}
 	}
 	e.mapEnd()
 }
 
 func (e *Encoder) kSliceW(rv reflect.Value, ti *typeInfo) {
 	var l = rvLenSlice(rv)
 	e.arrayStart(l)
 	if l > 0 {
 		fn := e.kSeqFn(ti.elem)
 		for j := 0; j < l; j++ {
 			e.arrayElem()
 			e.encodeValue(rvSliceIndex(rv, j, ti), fn)
 		}
 	}
 	e.arrayEnd()
 }
 
 func (e *Encoder) kArrayWMbs(rv reflect.Value, ti *typeInfo) {
 	var l = rv.Len()
 	if l == 0 {
 		e.mapStart(0)
 	} else {
 		e.haltOnMbsOddLen(l)
 		e.mapStart(l >> 1) // e.mapStart(l / 2)
 		fn := e.kSeqFn(ti.elem)
 		for j := 0; j < l; j++ {
 			if j&1 == 0 { // j%2 == 0 {
 				e.mapElemKey()
 			} else {
 				e.mapElemValue()
 			}
 			e.encodeValue(rv.Index(j), fn)
 		}
 	}
 	e.mapEnd()
 }
 
 func (e *Encoder) kArrayW(rv reflect.Value, ti *typeInfo) {
 	var l = rv.Len()
 	e.arrayStart(l)
 	if l > 0 {
 		fn := e.kSeqFn(ti.elem)
 		for j := 0; j < l; j++ {
 			e.arrayElem()
 			e.encodeValue(rv.Index(j), fn)
 		}
 	}
 	e.arrayEnd()
 }
 
 func (e *Encoder) kChan(f *codecFnInfo, rv reflect.Value) {
 	if f.ti.chandir&uint8(reflect.RecvDir) == 0 {
 		e.errorf("send-only channel cannot be encoded")
 	}
 	if !f.ti.mbs && uint8TypId == rt2id(f.ti.elem) {
 		e.kSliceBytesChan(rv)
 		return
 	}
 	rtslice := reflect.SliceOf(f.ti.elem)
 	rv = chanToSlice(rv, rtslice, e.h.ChanRecvTimeout)
 	ti := e.h.getTypeInfo(rt2id(rtslice), rtslice)
 	if f.ti.mbs {
 		e.kSliceWMbs(rv, ti)
 	} else {
 		e.kSliceW(rv, ti)
 	}
 }
 
 func (e *Encoder) kSlice(f *codecFnInfo, rv reflect.Value) {
 	if f.ti.mbs {
 		e.kSliceWMbs(rv, f.ti)
 	} else if f.ti.rtid == uint8SliceTypId || uint8TypId == rt2id(f.ti.elem) {
 		e.e.EncodeStringBytesRaw(rvGetBytes(rv))
 	} else {
 		e.kSliceW(rv, f.ti)
 	}
 }
 
 func (e *Encoder) kArray(f *codecFnInfo, rv reflect.Value) {
 	if f.ti.mbs {
 		e.kArrayWMbs(rv, f.ti)
 	} else if handleBytesWithinKArray && uint8TypId == rt2id(f.ti.elem) {
 		e.e.EncodeStringBytesRaw(rvGetArrayBytes(rv, []byte{}))
 	} else {
 		e.kArrayW(rv, f.ti)
 	}
 }
 
 func (e *Encoder) kSliceBytesChan(rv reflect.Value) {
 	// do not use range, so that the number of elements encoded
 	// does not change, and encoding does not hang waiting on someone to close chan.
 
 	bs0 := e.blist.peek(32, true)
 	bs := bs0
 
 	irv := rv2i(rv)
 	ch, ok := irv.(<-chan byte)
 	if !ok {
 		ch = irv.(chan byte)
 	}
 
 L1:
 	switch timeout := e.h.ChanRecvTimeout; {
 	case timeout == 0: // only consume available
 		for {
 			select {
 			case b := <-ch:
 				bs = append(bs, b)
 			default:
 				break L1
 			}
 		}
 	case timeout > 0: // consume until timeout
 		tt := time.NewTimer(timeout)
 		for {
 			select {
 			case b := <-ch:
 				bs = append(bs, b)
 			case <-tt.C:
 				// close(tt.C)
 				break L1
 			}
 		}
 	default: // consume until close
 		for b := range ch {
 			bs = append(bs, b)
 		}
 	}
 
 	e.e.EncodeStringBytesRaw(bs)
 	e.blist.put(bs)
 	if !byteSliceSameData(bs0, bs) {
 		e.blist.put(bs0)
 	}
 }
 
 func (e *Encoder) kStructSfi(f *codecFnInfo) []*structFieldInfo {
 	if e.h.Canonical {
 		return f.ti.sfi.sorted()
 	}
 	return f.ti.sfi.source()
 }
 
 func (e *Encoder) kStructNoOmitempty(f *codecFnInfo, rv reflect.Value) {
 	var tisfi []*structFieldInfo
 	if f.ti.toArray || e.h.StructToArray { // toArray
 		tisfi = f.ti.sfi.source()
 		e.arrayStart(len(tisfi))
 		for _, si := range tisfi {
 			e.arrayElem()
 			e.encodeValue(si.path.field(rv), nil)
 		}
 		e.arrayEnd()
 	} else {
 		tisfi = e.kStructSfi(f)
 		e.mapStart(len(tisfi))
 		keytyp := f.ti.keyType
 		for _, si := range tisfi {
 			e.mapElemKey()
 			e.kStructFieldKey(keytyp, si.path.encNameAsciiAlphaNum, si.encName)
 			e.mapElemValue()
 			e.encodeValue(si.path.field(rv), nil)
 		}
 		e.mapEnd()
 	}
 }
 
 func (e *Encoder) kStructFieldKey(keyType valueType, encNameAsciiAlphaNum bool, encName string) {
 	encStructFieldKey(encName, e.e, e.w(), keyType, encNameAsciiAlphaNum, e.js)
 }
 
 func (e *Encoder) kStruct(f *codecFnInfo, rv reflect.Value) {
 	var newlen int
 	ti := f.ti
 	toMap := !(ti.toArray || e.h.StructToArray)
 	var mf map[string]interface{}
 	if ti.flagMissingFielder {
 		mf = rv2i(rv).(MissingFielder).CodecMissingFields()
 		toMap = true
 		newlen += len(mf)
 	} else if ti.flagMissingFielderPtr {
 		rv2 := e.addrRV(rv, ti.rt, ti.ptr)
 		mf = rv2i(rv2).(MissingFielder).CodecMissingFields()
 		toMap = true
 		newlen += len(mf)
 	}
 	tisfi := ti.sfi.source()
 	newlen += len(tisfi)
 
 	var fkvs = e.slist.get(newlen)[:newlen]
 
 	recur := e.h.RecursiveEmptyCheck
 
 	var kv sfiRv
 	var j int
 	if toMap {
 		newlen = 0
 		for _, si := range e.kStructSfi(f) {
 			kv.r = si.path.field(rv)
 			if si.path.omitEmpty && isEmptyValue(kv.r, e.h.TypeInfos, recur) {
 				continue
 			}
 			kv.v = si
 			fkvs[newlen] = kv
 			newlen++
 		}
 
 		var mf2s []stringIntf
 		if len(mf) > 0 {
 			mf2s = make([]stringIntf, 0, len(mf))
 			for k, v := range mf {
 				if k == "" {
 					continue
 				}
 				if ti.infoFieldOmitempty && isEmptyValue(reflect.ValueOf(v), e.h.TypeInfos, recur) {
 					continue
 				}
 				mf2s = append(mf2s, stringIntf{k, v})
 			}
 		}
 
 		e.mapStart(newlen + len(mf2s))
 
 		// When there are missing fields, and Canonical flag is set,
 		// we cannot have the missing fields and struct fields sorted independently.
 		// We have to capture them together and sort as a unit.
 
 		if len(mf2s) > 0 && e.h.Canonical {
 			mf2w := make([]encStructFieldObj, newlen+len(mf2s))
 			for j = 0; j < newlen; j++ {
 				kv = fkvs[j]
 				mf2w[j] = encStructFieldObj{kv.v.encName, kv.r, nil, kv.v.path.encNameAsciiAlphaNum, true}
 			}
 			for _, v := range mf2s {
 				mf2w[j] = encStructFieldObj{v.v, reflect.Value{}, v.i, false, false}
 				j++
 			}
 			sort.Sort((encStructFieldObjSlice)(mf2w))
 			for _, v := range mf2w {
 				e.mapElemKey()
 				e.kStructFieldKey(ti.keyType, v.ascii, v.key)
 				e.mapElemValue()
 				if v.isRv {
 					e.encodeValue(v.rv, nil)
 				} else {
 					e.encode(v.intf)
 				}
 			}
 		} else {
 			keytyp := ti.keyType
 			for j = 0; j < newlen; j++ {
 				kv = fkvs[j]
 				e.mapElemKey()
 				e.kStructFieldKey(keytyp, kv.v.path.encNameAsciiAlphaNum, kv.v.encName)
 				e.mapElemValue()
 				e.encodeValue(kv.r, nil)
 			}
 			for _, v := range mf2s {
 				e.mapElemKey()
 				e.kStructFieldKey(keytyp, false, v.v)
 				e.mapElemValue()
 				e.encode(v.i)
 			}
 		}
 
 		e.mapEnd()
 	} else {
 		newlen = len(tisfi)
 		for i, si := range tisfi { // use unsorted array (to match sequence in struct)
 			kv.r = si.path.field(rv)
 			// use the zero value.
 			// if a reference or struct, set to nil (so you do not output too much)
 			if si.path.omitEmpty && isEmptyValue(kv.r, e.h.TypeInfos, recur) {
 				switch kv.r.Kind() {
 				case reflect.Struct, reflect.Interface, reflect.Ptr, reflect.Array, reflect.Map, reflect.Slice:
 					kv.r = reflect.Value{} //encode as nil
 				}
 			}
 			fkvs[i] = kv
 		}
 		// encode it all
 		e.arrayStart(newlen)
 		for j = 0; j < newlen; j++ {
 			e.arrayElem()
 			e.encodeValue(fkvs[j].r, nil)
 		}
 		e.arrayEnd()
 	}
 
 	// do not use defer. Instead, use explicit pool return at end of function.
 	// defer has a cost we are trying to avoid.
 	// If there is a panic and these slices are not returned, it is ok.
 	e.slist.put(fkvs)
 }
 
 func (e *Encoder) kMap(f *codecFnInfo, rv reflect.Value) {
 	l := rvLenMap(rv)
 	e.mapStart(l)
 	if l == 0 {
 		e.mapEnd()
 		return
 	}
 
 	// determine the underlying key and val encFn's for the map.
 	// This eliminates some work which is done for each loop iteration i.e.
 	// rv.Type(), ref.ValueOf(rt).Pointer(), then check map/list for fn.
 	//
 	// However, if kind is reflect.Interface, do not pre-determine the
 	// encoding type, because preEncodeValue may break it down to
 	// a concrete type and kInterface will bomb.
 
 	var keyFn, valFn *codecFn
 
 	ktypeKind := reflect.Kind(f.ti.keykind)
 	vtypeKind := reflect.Kind(f.ti.elemkind)
 
 	rtval := f.ti.elem
 	rtvalkind := vtypeKind
 	for rtvalkind == reflect.Ptr {
 		rtval = rtval.Elem()
 		rtvalkind = rtval.Kind()
 	}
 	if rtvalkind != reflect.Interface {
 		valFn = e.h.fn(rtval)
 	}
 
 	var rvv = mapAddrLoopvarRV(f.ti.elem, vtypeKind)
 
 	rtkey := f.ti.key
 	var keyTypeIsString = stringTypId == rt2id(rtkey) // rtkeyid
 	if keyTypeIsString {
 		keyFn = e.h.fn(rtkey)
 	} else {
 		for rtkey.Kind() == reflect.Ptr {
 			rtkey = rtkey.Elem()
 		}
 		if rtkey.Kind() != reflect.Interface {
 			keyFn = e.h.fn(rtkey)
 		}
 	}
 
 	if e.h.Canonical {
 		e.kMapCanonical(f.ti, rv, rvv, keyFn, valFn)
 		e.mapEnd()
 		return
 	}
 
 	var rvk = mapAddrLoopvarRV(f.ti.key, ktypeKind)
 
 	var it mapIter
 	mapRange(&it, rv, rvk, rvv, true)
 
 	for it.Next() {
 		e.mapElemKey()
 		if keyTypeIsString {
 			e.e.EncodeString(it.Key().String())
 		} else {
 			e.encodeValue(it.Key(), keyFn)
 		}
 		e.mapElemValue()
 		e.encodeValue(it.Value(), valFn)
 	}
 	it.Done()
 
 	e.mapEnd()
 }
 
 func (e *Encoder) kMapCanonical(ti *typeInfo, rv, rvv reflect.Value, keyFn, valFn *codecFn) {
 	// The base kind of the type of the map key is sufficient for ordering.
 	// We only do out of band if that kind is not ordered (number or string), bool or time.Time.
 	// If the key is a predeclared type, directly call methods on encDriver e.g. EncodeString
 	// but if not, call encodeValue, in case it has an extension registered or otherwise.
 	rtkey := ti.key
 	rtkeydecl := rtkey.PkgPath() == "" && rtkey.Name() != "" // key type is predeclared
 
 	mks := rv.MapKeys()
 	rtkeyKind := rtkey.Kind()
 	kfast := mapKeyFastKindFor(rtkeyKind)
 	visindirect := mapStoresElemIndirect(uintptr(ti.elemsize))
 	visref := refBitset.isset(ti.elemkind)
 
 	switch rtkeyKind {
 	case reflect.Bool:
 		// though bool keys make no sense in a map, it *could* happen.
 		// in that case, we MUST support it in reflection mode,
 		// as that is the fallback for even codecgen and others.
 
 		// sort the keys so that false comes before true
 		// ie if 2 keys in order (true, false), then swap them
 		if len(mks) == 2 && mks[0].Bool() {
 			mks[0], mks[1] = mks[1], mks[0]
 		}
 		for i := range mks {
 			e.mapElemKey()
 			if rtkeydecl {
 				e.e.EncodeBool(mks[i].Bool())
 			} else {
 				e.encodeValueNonNil(mks[i], keyFn)
 			}
 			e.mapElemValue()
 			e.encodeValue(mapGet(rv, mks[i], rvv, kfast, visindirect, visref), valFn)
 		}
 	case reflect.String:
 		mksv := make([]stringRv, len(mks))
 		for i, k := range mks {
 			v := &mksv[i]
 			v.r = k
 			v.v = k.String()
 		}
 		sort.Sort(stringRvSlice(mksv))
 		for i := range mksv {
 			e.mapElemKey()
 			if rtkeydecl {
 				e.e.EncodeString(mksv[i].v)
 			} else {
 				e.encodeValueNonNil(mksv[i].r, keyFn)
 			}
 			e.mapElemValue()
 			e.encodeValue(mapGet(rv, mksv[i].r, rvv, kfast, visindirect, visref), valFn)
 		}
 	case reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uint, reflect.Uintptr:
 		mksv := make([]uint64Rv, len(mks))
 		for i, k := range mks {
 			v := &mksv[i]
 			v.r = k
 			v.v = k.Uint()
 		}
 		sort.Sort(uint64RvSlice(mksv))
 		for i := range mksv {
 			e.mapElemKey()
 			if rtkeydecl {
 				e.e.EncodeUint(mksv[i].v)
 			} else {
 				e.encodeValueNonNil(mksv[i].r, keyFn)
 			}
 			e.mapElemValue()
 			e.encodeValue(mapGet(rv, mksv[i].r, rvv, kfast, visindirect, visref), valFn)
 		}
 	case reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Int:
 		mksv := make([]int64Rv, len(mks))
 		for i, k := range mks {
 			v := &mksv[i]
 			v.r = k
 			v.v = k.Int()
 		}
 		sort.Sort(int64RvSlice(mksv))
 		for i := range mksv {
 			e.mapElemKey()
 			if rtkeydecl {
 				e.e.EncodeInt(mksv[i].v)
 			} else {
 				e.encodeValueNonNil(mksv[i].r, keyFn)
 			}
 			e.mapElemValue()
 			e.encodeValue(mapGet(rv, mksv[i].r, rvv, kfast, visindirect, visref), valFn)
 		}
 	case reflect.Float32:
 		mksv := make([]float64Rv, len(mks))
 		for i, k := range mks {
 			v := &mksv[i]
 			v.r = k
 			v.v = k.Float()
 		}
 		sort.Sort(float64RvSlice(mksv))
 		for i := range mksv {
 			e.mapElemKey()
 			if rtkeydecl {
 				e.e.EncodeFloat32(float32(mksv[i].v))
 			} else {
 				e.encodeValueNonNil(mksv[i].r, keyFn)
 			}
 			e.mapElemValue()
 			e.encodeValue(mapGet(rv, mksv[i].r, rvv, kfast, visindirect, visref), valFn)
 		}
 	case reflect.Float64:
 		mksv := make([]float64Rv, len(mks))
 		for i, k := range mks {
 			v := &mksv[i]
 			v.r = k
 			v.v = k.Float()
 		}
 		sort.Sort(float64RvSlice(mksv))
 		for i := range mksv {
 			e.mapElemKey()
 			if rtkeydecl {
 				e.e.EncodeFloat64(mksv[i].v)
 			} else {
 				e.encodeValueNonNil(mksv[i].r, keyFn)
 			}
 			e.mapElemValue()
 			e.encodeValue(mapGet(rv, mksv[i].r, rvv, kfast, visindirect, visref), valFn)
 		}
 	default:
 		if rtkey == timeTyp {
 			mksv := make([]timeRv, len(mks))
 			for i, k := range mks {
 				v := &mksv[i]
 				v.r = k
 				v.v = rv2i(k).(time.Time)
 			}
 			sort.Sort(timeRvSlice(mksv))
 			for i := range mksv {
 				e.mapElemKey()
 				e.e.EncodeTime(mksv[i].v)
 				e.mapElemValue()
 				e.encodeValue(mapGet(rv, mksv[i].r, rvv, kfast, visindirect, visref), valFn)
 			}
 			break
 		}
 
 		// out-of-band
 		// first encode each key to a []byte first, then sort them, then record
 		bs0 := e.blist.get(len(mks) * 16)
 		mksv := bs0
 		mksbv := make([]bytesRv, len(mks))
 
 		func() {
 			// replicate sideEncode logic
 			defer func(wb bytesEncAppender, bytes bool, c containerState, state interface{}) {
 				e.wb = wb
 				e.bytes = bytes
 				e.c = c
 				e.e.restoreState(state)
 			}(e.wb, e.bytes, e.c, e.e.captureState())
 
 			// e2 := NewEncoderBytes(&mksv, e.hh)
 			e.wb = bytesEncAppender{mksv[:0], &mksv}
 			e.bytes = true
 			e.c = 0
 			e.e.resetState()
 
 			for i, k := range mks {
 				v := &mksbv[i]
 				l := len(mksv)
 
 				e.c = containerMapKey
 				e.encodeValue(k, nil)
 				e.atEndOfEncode()
 				e.w().end()
 
 				v.r = k
 				v.v = mksv[l:]
 			}
 		}()
 
 		sort.Sort(bytesRvSlice(mksbv))
 		for j := range mksbv {
 			e.mapElemKey()
 			e.encWr.writeb(mksbv[j].v)
 			e.mapElemValue()
 			e.encodeValue(mapGet(rv, mksbv[j].r, rvv, kfast, visindirect, visref), valFn)
 		}
 		e.blist.put(mksv)
 		if !byteSliceSameData(bs0, mksv) {
 			e.blist.put(bs0)
 		}
 	}
 }
 
 // Encoder writes an object to an output stream in a supported format.
 //
 // Encoder is NOT safe for concurrent use i.e. a Encoder cannot be used
 // concurrently in multiple goroutines.
 //
 // However, as Encoder could be allocation heavy to initialize, a Reset method is provided
 // so its state can be reused to decode new input streams repeatedly.
 // This is the idiomatic way to use.
 type Encoder struct {
 	panicHdl
 
 	e encDriver
 
 	h *BasicHandle
 
 	// hopefully, reduce derefencing cost by laying the encWriter inside the Encoder
 	encWr
 
 	// ---- cpu cache line boundary
 	hh Handle
 
 	blist bytesFreelist
 	err   error
 
 	// ---- cpu cache line boundary
 
 	// ---- writable fields during execution --- *try* to keep in sep cache line
 
 	// ci holds interfaces during an encoding (if CheckCircularRef=true)
 	//
 	// We considered using a []uintptr (slice of pointer addresses) retrievable via rv.UnsafeAddr.
 	// However, it is possible for the same pointer to point to 2 different types e.g.
 	//    type T struct { tHelper }
 	//    Here, for var v T; &v and &v.tHelper are the same pointer.
 	// Consequently, we need a tuple of type and pointer, which interface{} natively provides.
 	ci []interface{} // []uintptr
 
 	perType encPerType
 
 	slist sfiRvFreelist
 }
 
 // NewEncoder returns an Encoder for encoding into an io.Writer.
 //
 // For efficiency, Users are encouraged to configure WriterBufferSize on the handle
 // OR pass in a memory buffered writer (eg bufio.Writer, bytes.Buffer).
 func NewEncoder(w io.Writer, h Handle) *Encoder {
 	e := h.newEncDriver().encoder()
 	if w != nil {
 		e.Reset(w)
 	}
 	return e
 }
 
 // NewEncoderBytes returns an encoder for encoding directly and efficiently
 // into a byte slice, using zero-copying to temporary slices.
 //
 // It will potentially replace the output byte slice pointed to.
 // After encoding, the out parameter contains the encoded contents.
 func NewEncoderBytes(out *[]byte, h Handle) *Encoder {
 	e := h.newEncDriver().encoder()
 	if out != nil {
 		e.ResetBytes(out)
 	}
 	return e
 }
 
 func (e *Encoder) init(h Handle) {
 	initHandle(h)
 	e.err = errEncoderNotInitialized
 	e.bytes = true
 	e.hh = h
 	e.h = h.getBasicHandle()
 	e.be = e.hh.isBinary()
 }
 
 func (e *Encoder) w() *encWr {
 	return &e.encWr
 }
 
 func (e *Encoder) resetCommon() {
 	e.e.reset()
 	if e.ci != nil {
 		e.ci = e.ci[:0]
 	}
 	e.c = 0
 	e.calls = 0
 	e.seq = 0
 	e.err = nil
 }
 
 // Reset resets the Encoder with a new output stream.
 //
 // This accommodates using the state of the Encoder,
 // where it has "cached" information about sub-engines.
 func (e *Encoder) Reset(w io.Writer) {
 	e.bytes = false
 	if e.wf == nil {
 		e.wf = new(bufioEncWriter)
 	}
 	e.wf.reset(w, e.h.WriterBufferSize, &e.blist)
 	e.resetCommon()
 }
 
 // ResetBytes resets the Encoder with a new destination output []byte.
 func (e *Encoder) ResetBytes(out *[]byte) {
 	e.bytes = true
 	e.wb.reset(encInBytes(out), out)
 	e.resetCommon()
 }
 
 // Encode writes an object into a stream.
 //
 // Encoding can be configured via the struct tag for the fields.
 // The key (in the struct tags) that we look at is configurable.
 //
 // By default, we look up the "codec" key in the struct field's tags,
 // and fall bak to the "json" key if "codec" is absent.
 // That key in struct field's tag value is the key name,
 // followed by an optional comma and options.
 //
 // To set an option on all fields (e.g. omitempty on all fields), you
 // can create a field called _struct, and set flags on it. The options
 // which can be set on _struct are:
 //   - omitempty: so all fields are omitted if empty
 //   - toarray: so struct is encoded as an array
 //   - int: so struct key names are encoded as signed integers (instead of strings)
 //   - uint: so struct key names are encoded as unsigned integers (instead of strings)
 //   - float: so struct key names are encoded as floats (instead of strings)
 //
 // More details on these below.
 //
 // Struct values "usually" encode as maps. Each exported struct field is encoded unless:
 //   - the field's tag is "-", OR
 //   - the field is empty (empty or the zero value) and its tag specifies the "omitempty" option.
 //
 // When encoding as a map, the first string in the tag (before the comma)
 // is the map key string to use when encoding.
 // ...
 // This key is typically encoded as a string.
 // However, there are instances where the encoded stream has mapping keys encoded as numbers.
 // For example, some cbor streams have keys as integer codes in the stream, but they should map
 // to fields in a structured object. Consequently, a struct is the natural representation in code.
 // For these, configure the struct to encode/decode the keys as numbers (instead of string).
 // This is done with the int,uint or float option on the _struct field (see above).
 //
 // However, struct values may encode as arrays. This happens when:
 //   - StructToArray Encode option is set, OR
 //   - the tag on the _struct field sets the "toarray" option
 //
 // Note that omitempty is ignored when encoding struct values as arrays,
 // as an entry must be encoded for each field, to maintain its position.
 //
 // Values with types that implement MapBySlice are encoded as stream maps.
 //
 // The empty values (for omitempty option) are false, 0, any nil pointer
 // or interface value, and any array, slice, map, or string of length zero.
 //
 // Anonymous fields are encoded inline except:
 //   - the struct tag specifies a replacement name (first value)
 //   - the field is of an interface type
 //
 // Examples:
 //
 //	// NOTE: 'json:' can be used as struct tag key, in place 'codec:' below.
 //	type MyStruct struct {
 //	    _struct bool    `codec:",omitempty"`   //set omitempty for every field
 //	    Field1 string   `codec:"-"`            //skip this field
 //	    Field2 int      `codec:"myName"`       //Use key "myName" in encode stream
 //	    Field3 int32    `codec:",omitempty"`   //use key "Field3". Omit if empty.
 //	    Field4 bool     `codec:"f4,omitempty"` //use key "f4". Omit if empty.
 //	    io.Reader                              //use key "Reader".
 //	    MyStruct        `codec:"my1"           //use key "my1".
 //	    MyStruct                               //inline it
 //	    ...
 //	}
 //
 //	type MyStruct struct {
 //	    _struct bool    `codec:",toarray"`     //encode struct as an array
 //	}
 //
 //	type MyStruct struct {
 //	    _struct bool    `codec:",uint"`        //encode struct with "unsigned integer" keys
 //	    Field1 string   `codec:"1"`            //encode Field1 key using: EncodeInt(1)
 //	    Field2 string   `codec:"2"`            //encode Field2 key using: EncodeInt(2)
 //	}
 //
 // The mode of encoding is based on the type of the value. When a value is seen:
 //   - If a Selfer, call its CodecEncodeSelf method
 //   - If an extension is registered for it, call that extension function
 //   - If implements encoding.(Binary|Text|JSON)Marshaler, call Marshal(Binary|Text|JSON) method
 //   - Else encode it based on its reflect.Kind
 //
 // Note that struct field names and keys in map[string]XXX will be treated as symbols.
 // Some formats support symbols (e.g. binc) and will properly encode the string
 // only once in the stream, and use a tag to refer to it thereafter.
 func (e *Encoder) Encode(v interface{}) (err error) {
 	// tried to use closure, as runtime optimizes defer with no params.
 	// This seemed to be causing weird issues (like circular reference found, unexpected panic, etc).
 	// Also, see https://github.com/golang/go/issues/14939#issuecomment-417836139
 	if !debugging {
 		defer func() {
 			// if error occurred during encoding, return that error;
 			// else if error occurred on end'ing (i.e. during flush), return that error.
 			if x := recover(); x != nil {
 				panicValToErr(e, x, &e.err)
 				err = e.err
 			}
 		}()
 	}
 
 	e.MustEncode(v)
 	return
 }
 
 // MustEncode is like Encode, but panics if unable to Encode.
 //
 // Note: This provides insight to the code location that triggered the error.
 func (e *Encoder) MustEncode(v interface{}) {
 	halt.onerror(e.err)
 	if e.hh == nil {
 		halt.onerror(errNoFormatHandle)
 	}
 
 	e.calls++
 	e.encode(v)
 	e.calls--
 	if e.calls == 0 {
 		e.atEndOfEncode()
 		e.w().end()
 	}
 }
 
 // Release releases shared (pooled) resources.
 //
 // It is important to call Release() when done with an Encoder, so those resources
 // are released instantly for use by subsequently created Encoders.
 //
 // Deprecated: Release is a no-op as pooled resources are not used with an Encoder.
 // This method is kept for compatibility reasons only.
 func (e *Encoder) Release() {
 }
 
 func (e *Encoder) encode(iv interface{}) {
 	// MARKER: a switch with only concrete types can be optimized.
 	// consequently, we deal with nil and interfaces outside the switch.
 
 	if iv == nil {
 		e.e.EncodeNil()
 		return
 	}
 
 	rv, ok := isNil(iv)
 	if ok {
 		e.e.EncodeNil()
 		return
 	}
 
 	switch v := iv.(type) {
 	// case nil:
 	// case Selfer:
 	case Raw:
 		e.rawBytes(v)
 	case reflect.Value:
 		e.encodeValue(v, nil)
 
 	case string:
 		e.e.EncodeString(v)
 	case bool:
 		e.e.EncodeBool(v)
 	case int:
 		e.e.EncodeInt(int64(v))
 	case int8:
 		e.e.EncodeInt(int64(v))
 	case int16:
 		e.e.EncodeInt(int64(v))
 	case int32:
 		e.e.EncodeInt(int64(v))
 	case int64:
 		e.e.EncodeInt(v)
 	case uint:
 		e.e.EncodeUint(uint64(v))
 	case uint8:
 		e.e.EncodeUint(uint64(v))
 	case uint16:
 		e.e.EncodeUint(uint64(v))
 	case uint32:
 		e.e.EncodeUint(uint64(v))
 	case uint64:
 		e.e.EncodeUint(v)
 	case uintptr:
 		e.e.EncodeUint(uint64(v))
 	case float32:
 		e.e.EncodeFloat32(v)
 	case float64:
 		e.e.EncodeFloat64(v)
 	case complex64:
 		e.encodeComplex64(v)
 	case complex128:
 		e.encodeComplex128(v)
 	case time.Time:
 		e.e.EncodeTime(v)
 	case []byte:
 		e.e.EncodeStringBytesRaw(v)
 	case *Raw:
 		e.rawBytes(*v)
 	case *string:
 		e.e.EncodeString(*v)
 	case *bool:
 		e.e.EncodeBool(*v)
 	case *int:
 		e.e.EncodeInt(int64(*v))
 	case *int8:
 		e.e.EncodeInt(int64(*v))
 	case *int16:
 		e.e.EncodeInt(int64(*v))
 	case *int32:
 		e.e.EncodeInt(int64(*v))
 	case *int64:
 		e.e.EncodeInt(*v)
 	case *uint:
 		e.e.EncodeUint(uint64(*v))
 	case *uint8:
 		e.e.EncodeUint(uint64(*v))
 	case *uint16:
 		e.e.EncodeUint(uint64(*v))
 	case *uint32:
 		e.e.EncodeUint(uint64(*v))
 	case *uint64:
 		e.e.EncodeUint(*v)
 	case *uintptr:
 		e.e.EncodeUint(uint64(*v))
 	case *float32:
 		e.e.EncodeFloat32(*v)
 	case *float64:
 		e.e.EncodeFloat64(*v)
 	case *complex64:
 		e.encodeComplex64(*v)
 	case *complex128:
 		e.encodeComplex128(*v)
 	case *time.Time:
 		e.e.EncodeTime(*v)
 	case *[]byte:
 		if *v == nil {
 			e.e.EncodeNil()
 		} else {
 			e.e.EncodeStringBytesRaw(*v)
 		}
 	default:
 		// we can't check non-predefined types, as they might be a Selfer or extension.
 		if skipFastpathTypeSwitchInDirectCall || !fastpathEncodeTypeSwitch(iv, e) {
 			e.encodeValue(rv, nil)
 		}
 	}
 }
 
 // encodeValue will encode a value.
 //
 // Note that encodeValue will handle nil in the stream early, so that the
 // subsequent calls i.e. kXXX methods, etc do not have to handle it themselves.
 func (e *Encoder) encodeValue(rv reflect.Value, fn *codecFn) {
 	// if a valid fn is passed, it MUST BE for the dereferenced type of rv
 
 	// MARKER: We check if value is nil here, so that the kXXX method do not have to.
 
 	var sptr interface{}
 	var rvp reflect.Value
 	var rvpValid bool
 TOP:
 	switch rv.Kind() {
 	case reflect.Ptr:
 		if rvIsNil(rv) {
 			e.e.EncodeNil()
 			return
 		}
 		rvpValid = true
 		rvp = rv
 		rv = rv.Elem()
 		goto TOP
 	case reflect.Interface:
 		if rvIsNil(rv) {
 			e.e.EncodeNil()
 			return
 		}
 		rvpValid = false
 		rvp = reflect.Value{}
 		rv = rv.Elem()
 		goto TOP
 	case reflect.Struct:
 		if rvpValid && e.h.CheckCircularRef {
 			sptr = rv2i(rvp)
 			for _, vv := range e.ci {
 				if eq4i(sptr, vv) { // error if sptr already seen
 					e.errorf("circular reference found: %p, %T", sptr, sptr)
 				}
 			}
 			e.ci = append(e.ci, sptr)
 		}
 	case reflect.Slice, reflect.Map, reflect.Chan:
 		if rvIsNil(rv) {
 			e.e.EncodeNil()
 			return
 		}
 	case reflect.Invalid, reflect.Func:
 		e.e.EncodeNil()
 		return
 	}
 
 	if fn == nil {
 		fn = e.h.fn(rv.Type())
 	}
 
 	if !fn.i.addrE { // typically, addrE = false, so check it first
 		// keep rv same
 	} else if rvpValid {
 		rv = rvp
 	} else {
 		rv = e.addrRV(rv, fn.i.ti.rt, fn.i.ti.ptr)
 	}
 	fn.fe(e, &fn.i, rv)
 
 	if sptr != nil { // remove sptr
 		e.ci = e.ci[:len(e.ci)-1]
 	}
 }
 
 // encodeValueNonNil can encode a number, bool, or string
 // OR non-nil values of kind map, slice and chan.
 func (e *Encoder) encodeValueNonNil(rv reflect.Value, fn *codecFn) {
 	if fn == nil {
 		fn = e.h.fn(rv.Type())
 	}
 
 	if fn.i.addrE { // typically, addrE = false, so check it first
 		rv = e.addrRV(rv, fn.i.ti.rt, fn.i.ti.ptr)
 	}
 	fn.fe(e, &fn.i, rv)
 }
 
 // addrRV returns a addressable value which may be readonly
 func (e *Encoder) addrRV(rv reflect.Value, typ, ptrType reflect.Type) (rva reflect.Value) {
 	if rv.CanAddr() {
 		return rvAddr(rv, ptrType)
 	}
 	if e.h.NoAddressableReadonly {
 		rva = reflect.New(typ)
 		rvSetDirect(rva.Elem(), rv)
 		return
 	}
 	return rvAddr(e.perType.AddressableRO(rv), ptrType)
 }
 
 func (e *Encoder) marshalUtf8(bs []byte, fnerr error) {
 	e.onerror(fnerr)
 	if bs == nil {
 		e.e.EncodeNil()
 	} else {
 		e.e.EncodeString(stringView(bs))
 	}
 }
 
 func (e *Encoder) marshalAsis(bs []byte, fnerr error) {
 	e.onerror(fnerr)
 	if bs == nil {
 		e.e.EncodeNil()
 	} else {
 		e.encWr.writeb(bs) // e.asis(bs)
 	}
 }
 
 func (e *Encoder) marshalRaw(bs []byte, fnerr error) {
 	e.onerror(fnerr)
 	if bs == nil {
 		e.e.EncodeNil()
 	} else {
 		e.e.EncodeStringBytesRaw(bs)
 	}
 }
 
 func (e *Encoder) rawBytes(vv Raw) {
 	v := []byte(vv)
 	if !e.h.Raw {
 		e.errorf("Raw values cannot be encoded: %v", v)
 	}
 	e.encWr.writeb(v)
 }
 
 func (e *Encoder) wrapErr(v error, err *error) {
 	*err = wrapCodecErr(v, e.hh.Name(), 0, true)
 }
 
 // ---- container tracker methods
 // Note: We update the .c after calling the callback.
 // This way, the callback can know what the last status was.
 
 func (e *Encoder) mapStart(length int) {
 	e.e.WriteMapStart(length)
 	e.c = containerMapStart
 }
 
 func (e *Encoder) mapElemKey() {
 	if e.js {
 		e.jsondriver().WriteMapElemKey()
 	}
 	e.c = containerMapKey
 }
 
 func (e *Encoder) mapElemValue() {
 	if e.js {
 		e.jsondriver().WriteMapElemValue()
 	}
 	e.c = containerMapValue
 }
 
 func (e *Encoder) mapEnd() {
 	e.e.WriteMapEnd()
 	e.c = 0
 }
 
 func (e *Encoder) arrayStart(length int) {
 	e.e.WriteArrayStart(length)
 	e.c = containerArrayStart
 }
 
 func (e *Encoder) arrayElem() {
 	if e.js {
 		e.jsondriver().WriteArrayElem()
 	}
 	e.c = containerArrayElem
 }
 
 func (e *Encoder) arrayEnd() {
 	e.e.WriteArrayEnd()
 	e.c = 0
 }
 
 // ----------
 
 func (e *Encoder) haltOnMbsOddLen(length int) {
 	if length&1 != 0 { // similar to &1==1 or %2 == 1
 		e.errorf("mapBySlice requires even slice length, but got %v", length)
 	}
 }
 
 func (e *Encoder) atEndOfEncode() {
 	// e.e.atEndOfEncode()
 	if e.js {
 		e.jsondriver().atEndOfEncode()
 	}
 }
 
 func (e *Encoder) sideEncode(v interface{}, basetype reflect.Type, bs *[]byte) {
 	// rv := baseRV(v)
 	// e2 := NewEncoderBytes(bs, e.hh)
 	// e2.encodeValue(rv, e2.h.fnNoExt(basetype))
 	// e2.atEndOfEncode()
 	// e2.w().end()
 
 	defer func(wb bytesEncAppender, bytes bool, c containerState, state interface{}) {
 		e.wb = wb
 		e.bytes = bytes
 		e.c = c
 		e.e.restoreState(state)
 	}(e.wb, e.bytes, e.c, e.e.captureState())
 
 	e.wb = bytesEncAppender{encInBytes(bs)[:0], bs}
 	e.bytes = true
 	e.c = 0
 	e.e.resetState()
 
 	// must call using fnNoExt
 	rv := baseRV(v)
 	e.encodeValue(rv, e.h.fnNoExt(basetype))
 	e.atEndOfEncode()
 	e.w().end()
 }
 
 func encInBytes(out *[]byte) (in []byte) {
 	in = *out
 	if in == nil {
 		in = make([]byte, defEncByteBufSize)
 	}
 	return
 }
 
 func encStructFieldKey(encName string, ee encDriver, w *encWr,
 	keyType valueType, encNameAsciiAlphaNum bool, js bool) {
 	// use if-else-if, not switch (which compiles to binary-search)
 	// since keyType is typically valueTypeString, branch prediction is pretty good.
 
 	if keyType == valueTypeString {
 		if js && encNameAsciiAlphaNum { // keyType == valueTypeString
 			w.writeqstr(encName)
 		} else { // keyType == valueTypeString
 			ee.EncodeString(encName)
 		}
 	} else if keyType == valueTypeInt {
 		ee.EncodeInt(must.Int(strconv.ParseInt(encName, 10, 64)))
 	} else if keyType == valueTypeUint {
 		ee.EncodeUint(must.Uint(strconv.ParseUint(encName, 10, 64)))
 	} else if keyType == valueTypeFloat {
 		ee.EncodeFloat64(must.Float(strconv.ParseFloat(encName, 64)))
 	} else {
 		halt.errorf("invalid struct key type: %v", keyType)
 	}
 }