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encode.go
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encode.go
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// Copyright (c) Faye Amacker. All rights reserved.
// Licensed under the MIT License. See LICENSE in the project root for license information.
package cbor
import (
"bytes"
"encoding"
"encoding/binary"
"errors"
"io"
"math"
"math/big"
"reflect"
"sort"
"strconv"
"sync"
"time"
"github.com/x448/float16"
)
// Marshal returns the CBOR encoding of v using default encoding options.
// See EncOptions for encoding options.
//
// Marshal uses the following encoding rules:
//
// If value implements the Marshaler interface, Marshal calls its
// MarshalCBOR method.
//
// If value implements encoding.BinaryMarshaler, Marhsal calls its
// MarshalBinary method and encode it as CBOR byte string.
//
// Boolean values encode as CBOR booleans (type 7).
//
// Positive integer values encode as CBOR positive integers (type 0).
//
// Negative integer values encode as CBOR negative integers (type 1).
//
// Floating point values encode as CBOR floating points (type 7).
//
// String values encode as CBOR text strings (type 3).
//
// []byte values encode as CBOR byte strings (type 2).
//
// Array and slice values encode as CBOR arrays (type 4).
//
// Map values encode as CBOR maps (type 5).
//
// Struct values encode as CBOR maps (type 5). Each exported struct field
// becomes a pair with field name encoded as CBOR text string (type 3) and
// field value encoded based on its type. See struct tag option "keyasint"
// to encode field name as CBOR integer (type 0 and 1). Also see struct
// tag option "toarray" for special field "_" to encode struct values as
// CBOR array (type 4).
//
// Marshal supports format string stored under the "cbor" key in the struct
// field's tag. CBOR format string can specify the name of the field,
// "omitempty" and "keyasint" options, and special case "-" for field omission.
// If "cbor" key is absent, Marshal uses "json" key.
//
// Struct field name is treated as integer if it has "keyasint" option in
// its format string. The format string must specify an integer as its
// field name.
//
// Special struct field "_" is used to specify struct level options, such as
// "toarray". "toarray" option enables Go struct to be encoded as CBOR array.
// "omitempty" is disabled by "toarray" to ensure that the same number
// of elements are encoded every time.
//
// Anonymous struct fields are marshaled as if their exported fields
// were fields in the outer struct. Marshal follows the same struct fields
// visibility rules used by JSON encoding package.
//
// time.Time values encode as text strings specified in RFC3339 or numerical
// representation of seconds since January 1, 1970 UTC depending on
// EncOptions.Time setting. Also See EncOptions.TimeTag to encode
// time.Time as CBOR tag with tag number 0 or 1.
//
// big.Int values encode as CBOR integers (type 0 and 1) if values fit.
// Otherwise, big.Int values encode as CBOR bignums (tag 2 and 3). See
// EncOptions.BigIntConvert to always encode big.Int values as CBOR
// bignums.
//
// Pointer values encode as the value pointed to.
//
// Interface values encode as the value stored in the interface.
//
// Nil slice/map/pointer/interface values encode as CBOR nulls (type 7).
//
// Values of other types cannot be encoded in CBOR. Attempting
// to encode such a value causes Marshal to return an UnsupportedTypeError.
func Marshal(v interface{}) ([]byte, error) {
return defaultEncMode.Marshal(v)
}
// Marshaler is the interface implemented by types that can marshal themselves
// into valid CBOR.
type Marshaler interface {
MarshalCBOR() ([]byte, error)
}
// MarshalerError represents error from checking encoded CBOR data item
// returned from MarshalCBOR for well-formedness and some very limited tag validation.
type MarshalerError struct {
typ reflect.Type
err error
}
func (e *MarshalerError) Error() string {
return "cbor: error calling MarshalCBOR for type " +
e.typ.String() +
": " + e.err.Error()
}
func (e *MarshalerError) Unwrap() error {
return e.err
}
// UnsupportedTypeError is returned by Marshal when attempting to encode value
// of an unsupported type.
type UnsupportedTypeError struct {
Type reflect.Type
}
func (e *UnsupportedTypeError) Error() string {
return "cbor: unsupported type: " + e.Type.String()
}
// UnsupportedValueError is returned by Marshal when attempting to encode an
// unsupported value.
type UnsupportedValueError struct {
msg string
}
func (e *UnsupportedValueError) Error() string {
return "cbor: unsupported value: " + e.msg
}
// SortMode identifies supported sorting order.
type SortMode int
const (
// SortNone means no sorting.
SortNone SortMode = 0
// SortLengthFirst causes map keys or struct fields to be sorted such that:
// - If two keys have different lengths, the shorter one sorts earlier;
// - If two keys have the same length, the one with the lower value in
// (byte-wise) lexical order sorts earlier.
// It is used in "Canonical CBOR" encoding in RFC 7049 3.9.
SortLengthFirst SortMode = 1
// SortBytewiseLexical causes map keys or struct fields to be sorted in the
// bytewise lexicographic order of their deterministic CBOR encodings.
// It is used in "CTAP2 Canonical CBOR" and "Core Deterministic Encoding"
// in RFC 7049bis.
SortBytewiseLexical SortMode = 2
// SortCanonical is used in "Canonical CBOR" encoding in RFC 7049 3.9.
SortCanonical SortMode = SortLengthFirst
// SortCTAP2 is used in "CTAP2 Canonical CBOR".
SortCTAP2 SortMode = SortBytewiseLexical
// SortCoreDeterministic is used in "Core Deterministic Encoding" in RFC 7049bis.
SortCoreDeterministic SortMode = SortBytewiseLexical
maxSortMode SortMode = 3
)
func (sm SortMode) valid() bool {
return sm >= 0 && sm < maxSortMode
}
// StringMode specifies how to encode Go string values.
type StringMode int
const (
// StringToTextString encodes Go string to CBOR text string (major type 3).
StringToTextString StringMode = iota
// StringToByteString encodes Go string to CBOR byte string (major type 2).
StringToByteString
)
func (st StringMode) cborType() (cborType, error) {
switch st {
case StringToTextString:
return cborTypeTextString, nil
case StringToByteString:
return cborTypeByteString, nil
}
return 0, errors.New("cbor: invalid StringType " + strconv.Itoa(int(st)))
}
// ShortestFloatMode specifies which floating-point format should
// be used as the shortest possible format for CBOR encoding.
// It is not used for encoding Infinity and NaN values.
type ShortestFloatMode int
const (
// ShortestFloatNone makes float values encode without any conversion.
// This is the default for ShortestFloatMode in v1.
// E.g. a float32 in Go will encode to CBOR float32. And
// a float64 in Go will encode to CBOR float64.
ShortestFloatNone ShortestFloatMode = iota
// ShortestFloat16 specifies float16 as the shortest form that preserves value.
// E.g. if float64 can convert to float32 while preserving value, then
// encoding will also try to convert float32 to float16. So a float64 might
// encode as CBOR float64, float32 or float16 depending on the value.
ShortestFloat16
maxShortestFloat
)
func (sfm ShortestFloatMode) valid() bool {
return sfm >= 0 && sfm < maxShortestFloat
}
// NaNConvertMode specifies how to encode NaN and overrides ShortestFloatMode.
// ShortestFloatMode is not used for encoding Infinity and NaN values.
type NaNConvertMode int
const (
// NaNConvert7e00 always encodes NaN to 0xf97e00 (CBOR float16 = 0x7e00).
NaNConvert7e00 NaNConvertMode = iota
// NaNConvertNone never modifies or converts NaN to other representations
// (float64 NaN stays float64, etc. even if it can use float16 without losing
// any bits).
NaNConvertNone
// NaNConvertPreserveSignal converts NaN to the smallest form that preserves
// value (quiet bit + payload) as described in RFC 7049bis Draft 12.
NaNConvertPreserveSignal
// NaNConvertQuiet always forces quiet bit = 1 and shortest form that preserves
// NaN payload.
NaNConvertQuiet
maxNaNConvert
)
func (ncm NaNConvertMode) valid() bool {
return ncm >= 0 && ncm < maxNaNConvert
}
// InfConvertMode specifies how to encode Infinity and overrides ShortestFloatMode.
// ShortestFloatMode is not used for encoding Infinity and NaN values.
type InfConvertMode int
const (
// InfConvertFloat16 always converts Inf to lossless IEEE binary16 (float16).
InfConvertFloat16 InfConvertMode = iota
// InfConvertNone never converts (used by CTAP2 Canonical CBOR).
InfConvertNone
maxInfConvert
)
func (icm InfConvertMode) valid() bool {
return icm >= 0 && icm < maxInfConvert
}
// TimeMode specifies how to encode time.Time values.
type TimeMode int
const (
// TimeUnix causes time.Time to be encoded as epoch time in integer with second precision.
TimeUnix TimeMode = iota
// TimeUnixMicro causes time.Time to be encoded as epoch time in float-point rounded to microsecond precision.
TimeUnixMicro
// TimeUnixDynamic causes time.Time to be encoded as integer if time.Time doesn't have fractional seconds,
// otherwise float-point rounded to microsecond precision.
TimeUnixDynamic
// TimeRFC3339 causes time.Time to be encoded as RFC3339 formatted string with second precision.
TimeRFC3339
// TimeRFC3339Nano causes time.Time to be encoded as RFC3339 formatted string with nanosecond precision.
TimeRFC3339Nano
maxTimeMode
)
func (tm TimeMode) valid() bool {
return tm >= 0 && tm < maxTimeMode
}
// BigIntConvertMode specifies how to encode big.Int values.
type BigIntConvertMode int
const (
// BigIntConvertShortest makes big.Int encode to CBOR integer if value fits.
// E.g. if big.Int value can be converted to CBOR integer while preserving
// value, encoder will encode it to CBOR integer (major type 0 or 1).
BigIntConvertShortest BigIntConvertMode = iota
// BigIntConvertNone makes big.Int encode to CBOR bignum (tag 2 or 3) without
// converting it to another CBOR type.
BigIntConvertNone
maxBigIntConvert
)
func (bim BigIntConvertMode) valid() bool {
return bim >= 0 && bim < maxBigIntConvert
}
// NilContainersMode specifies how to encode nil slices and maps.
type NilContainersMode int
const (
// NilContainerAsNull encodes nil slices and maps as CBOR null.
// This is the default.
NilContainerAsNull NilContainersMode = iota
// NilContainerAsEmpty encodes nil slices and maps as
// empty container (CBOR bytestring, array, or map).
NilContainerAsEmpty
maxNilContainersMode
)
func (m NilContainersMode) valid() bool {
return m >= 0 && m < maxNilContainersMode
}
// OmitEmptyMode specifies how to encode struct fields with omitempty tag.
// The default behavior omits if field value would encode as empty CBOR value.
type OmitEmptyMode int
const (
// OmitEmptyCBORValue specifies that struct fields tagged with "omitempty"
// should be omitted from encoding if the field would be encoded as an empty
// CBOR value, such as CBOR false, 0, 0.0, nil, empty byte, empty string,
// empty array, or empty map.
OmitEmptyCBORValue OmitEmptyMode = iota
// OmitEmptyGoValue specifies that struct fields tagged with "omitempty"
// should be omitted from encoding if the field has an empty Go value,
// defined as false, 0, 0.0, a nil pointer, a nil interface value, and
// any empty array, slice, map, or string.
// This behavior is the same as the current (aka v1) encoding/json package
// included in Go.
OmitEmptyGoValue
maxOmitEmptyMode
)
func (om OmitEmptyMode) valid() bool {
return om >= 0 && om < maxOmitEmptyMode
}
// FieldNameMode specifies the CBOR type to use when encoding struct field names.
type FieldNameMode int
const (
// FieldNameToTextString encodes struct fields to CBOR text string (major type 3).
FieldNameToTextString FieldNameMode = iota
// FieldNameToTextString encodes struct fields to CBOR byte string (major type 2).
FieldNameToByteString
maxFieldNameMode
)
func (fnm FieldNameMode) valid() bool {
return fnm >= 0 && fnm < maxFieldNameMode
}
// EncOptions specifies encoding options.
type EncOptions struct {
// Sort specifies sorting order.
Sort SortMode
// ShortestFloat specifies the shortest floating-point encoding that preserves
// the value being encoded.
ShortestFloat ShortestFloatMode
// NaNConvert specifies how to encode NaN and it overrides ShortestFloatMode.
NaNConvert NaNConvertMode
// InfConvert specifies how to encode Inf and it overrides ShortestFloatMode.
InfConvert InfConvertMode
// BigIntConvert specifies how to encode big.Int values.
BigIntConvert BigIntConvertMode
// Time specifies how to encode time.Time.
Time TimeMode
// TimeTag allows time.Time to be encoded with a tag number.
// RFC3339 format gets tag number 0, and numeric epoch time tag number 1.
TimeTag EncTagMode
// IndefLength specifies whether to allow indefinite length CBOR items.
IndefLength IndefLengthMode
// NilContainers specifies how to encode nil slices and maps.
NilContainers NilContainersMode
// TagsMd specifies whether to allow CBOR tags (major type 6).
TagsMd TagsMode
// OmitEmptyMode specifies how to encode struct fields with omitempty tag.
OmitEmpty OmitEmptyMode
// String specifies which CBOR type to use when encoding Go strings.
// - CBOR text string (major type 3) is default
// - CBOR byte string (major type 2)
String StringMode
// FieldName specifies the CBOR type to use when encoding struct field names.
FieldName FieldNameMode
}
// CanonicalEncOptions returns EncOptions for "Canonical CBOR" encoding,
// defined in RFC 7049 Section 3.9 with the following rules:
//
// 1. "Integers must be as small as possible."
// 2. "The expression of lengths in major types 2 through 5 must be as short as possible."
// 3. The keys in every map must be sorted in length-first sorting order.
// See SortLengthFirst for details.
// 4. "Indefinite-length items must be made into definite-length items."
// 5. "If a protocol allows for IEEE floats, then additional canonicalization rules might
// need to be added. One example rule might be to have all floats start as a 64-bit
// float, then do a test conversion to a 32-bit float; if the result is the same numeric
// value, use the shorter value and repeat the process with a test conversion to a
// 16-bit float. (This rule selects 16-bit float for positive and negative Infinity
// as well.) Also, there are many representations for NaN. If NaN is an allowed value,
// it must always be represented as 0xf97e00."
func CanonicalEncOptions() EncOptions {
return EncOptions{
Sort: SortCanonical,
ShortestFloat: ShortestFloat16,
NaNConvert: NaNConvert7e00,
InfConvert: InfConvertFloat16,
IndefLength: IndefLengthForbidden,
}
}
// CTAP2EncOptions returns EncOptions for "CTAP2 Canonical CBOR" encoding,
// defined in CTAP specification, with the following rules:
//
// 1. "Integers must be encoded as small as possible."
// 2. "The representations of any floating-point values are not changed."
// 3. "The expression of lengths in major types 2 through 5 must be as short as possible."
// 4. "Indefinite-length items must be made into definite-length items.""
// 5. The keys in every map must be sorted in bytewise lexicographic order.
// See SortBytewiseLexical for details.
// 6. "Tags as defined in Section 2.4 in [RFC7049] MUST NOT be present."
func CTAP2EncOptions() EncOptions {
return EncOptions{
Sort: SortCTAP2,
ShortestFloat: ShortestFloatNone,
NaNConvert: NaNConvertNone,
InfConvert: InfConvertNone,
IndefLength: IndefLengthForbidden,
TagsMd: TagsForbidden,
}
}
// CoreDetEncOptions returns EncOptions for "Core Deterministic" encoding,
// defined in RFC 7049bis with the following rules:
//
// 1. "Preferred serialization MUST be used. In particular, this means that arguments
// (see Section 3) for integers, lengths in major types 2 through 5, and tags MUST
// be as short as possible"
// "Floating point values also MUST use the shortest form that preserves the value"
// 2. "Indefinite-length items MUST NOT appear."
// 3. "The keys in every map MUST be sorted in the bytewise lexicographic order of
// their deterministic encodings."
func CoreDetEncOptions() EncOptions {
return EncOptions{
Sort: SortCoreDeterministic,
ShortestFloat: ShortestFloat16,
NaNConvert: NaNConvert7e00,
InfConvert: InfConvertFloat16,
IndefLength: IndefLengthForbidden,
}
}
// PreferredUnsortedEncOptions returns EncOptions for "Preferred Serialization" encoding,
// defined in RFC 7049bis with the following rules:
//
// 1. "The preferred serialization always uses the shortest form of representing the argument
// (Section 3);"
// 2. "it also uses the shortest floating-point encoding that preserves the value being
// encoded (see Section 5.5)."
// "The preferred encoding for a floating-point value is the shortest floating-point encoding
// that preserves its value, e.g., 0xf94580 for the number 5.5, and 0xfa45ad9c00 for the
// number 5555.5, unless the CBOR-based protocol specifically excludes the use of the shorter
// floating-point encodings. For NaN values, a shorter encoding is preferred if zero-padding
// the shorter significand towards the right reconstitutes the original NaN value (for many
// applications, the single NaN encoding 0xf97e00 will suffice)."
// 3. "Definite length encoding is preferred whenever the length is known at the time the
// serialization of the item starts."
func PreferredUnsortedEncOptions() EncOptions {
return EncOptions{
Sort: SortNone,
ShortestFloat: ShortestFloat16,
NaNConvert: NaNConvert7e00,
InfConvert: InfConvertFloat16,
}
}
// EncMode returns EncMode with immutable options and no tags (safe for concurrency).
func (opts EncOptions) EncMode() (EncMode, error) {
return opts.encMode()
}
// EncModeWithTags returns EncMode with options and tags that are both immutable (safe for concurrency).
func (opts EncOptions) EncModeWithTags(tags TagSet) (EncMode, error) {
if opts.TagsMd == TagsForbidden {
return nil, errors.New("cbor: cannot create EncMode with TagSet when TagsMd is TagsForbidden")
}
if tags == nil {
return nil, errors.New("cbor: cannot create EncMode with nil value as TagSet")
}
em, err := opts.encMode()
if err != nil {
return nil, err
}
// Copy tags
ts := tagSet(make(map[reflect.Type]*tagItem))
syncTags := tags.(*syncTagSet)
syncTags.RLock()
for contentType, tag := range syncTags.t {
if tag.opts.EncTag != EncTagNone {
ts[contentType] = tag
}
}
syncTags.RUnlock()
if len(ts) > 0 {
em.tags = ts
}
return em, nil
}
// EncModeWithSharedTags returns EncMode with immutable options and mutable shared tags (safe for concurrency).
func (opts EncOptions) EncModeWithSharedTags(tags TagSet) (EncMode, error) {
if opts.TagsMd == TagsForbidden {
return nil, errors.New("cbor: cannot create EncMode with TagSet when TagsMd is TagsForbidden")
}
if tags == nil {
return nil, errors.New("cbor: cannot create EncMode with nil value as TagSet")
}
em, err := opts.encMode()
if err != nil {
return nil, err
}
em.tags = tags
return em, nil
}
func (opts EncOptions) encMode() (*encMode, error) {
if !opts.Sort.valid() {
return nil, errors.New("cbor: invalid SortMode " + strconv.Itoa(int(opts.Sort)))
}
if !opts.ShortestFloat.valid() {
return nil, errors.New("cbor: invalid ShortestFloatMode " + strconv.Itoa(int(opts.ShortestFloat)))
}
if !opts.NaNConvert.valid() {
return nil, errors.New("cbor: invalid NaNConvertMode " + strconv.Itoa(int(opts.NaNConvert)))
}
if !opts.InfConvert.valid() {
return nil, errors.New("cbor: invalid InfConvertMode " + strconv.Itoa(int(opts.InfConvert)))
}
if !opts.BigIntConvert.valid() {
return nil, errors.New("cbor: invalid BigIntConvertMode " + strconv.Itoa(int(opts.BigIntConvert)))
}
if !opts.Time.valid() {
return nil, errors.New("cbor: invalid TimeMode " + strconv.Itoa(int(opts.Time)))
}
if !opts.TimeTag.valid() {
return nil, errors.New("cbor: invalid TimeTag " + strconv.Itoa(int(opts.TimeTag)))
}
if !opts.IndefLength.valid() {
return nil, errors.New("cbor: invalid IndefLength " + strconv.Itoa(int(opts.IndefLength)))
}
if !opts.NilContainers.valid() {
return nil, errors.New("cbor: invalid NilContainers " + strconv.Itoa(int(opts.NilContainers)))
}
if !opts.TagsMd.valid() {
return nil, errors.New("cbor: invalid TagsMd " + strconv.Itoa(int(opts.TagsMd)))
}
if opts.TagsMd == TagsForbidden && opts.TimeTag == EncTagRequired {
return nil, errors.New("cbor: cannot set TagsMd to TagsForbidden when TimeTag is EncTagRequired")
}
if !opts.OmitEmpty.valid() {
return nil, errors.New("cbor: invalid OmitEmpty " + strconv.Itoa(int(opts.OmitEmpty)))
}
stringMajorType, err := opts.String.cborType()
if err != nil {
return nil, err
}
if !opts.FieldName.valid() {
return nil, errors.New("cbor: invalid FieldName " + strconv.Itoa(int(opts.FieldName)))
}
em := encMode{
sort: opts.Sort,
shortestFloat: opts.ShortestFloat,
nanConvert: opts.NaNConvert,
infConvert: opts.InfConvert,
bigIntConvert: opts.BigIntConvert,
time: opts.Time,
timeTag: opts.TimeTag,
indefLength: opts.IndefLength,
nilContainers: opts.NilContainers,
tagsMd: opts.TagsMd,
omitEmpty: opts.OmitEmpty,
stringType: opts.String,
stringMajorType: stringMajorType,
fieldName: opts.FieldName,
}
return &em, nil
}
// EncMode is the main interface for CBOR encoding.
type EncMode interface {
Marshal(v interface{}) ([]byte, error)
NewEncoder(w io.Writer) *Encoder
EncOptions() EncOptions
}
type encMode struct {
tags tagProvider
sort SortMode
shortestFloat ShortestFloatMode
nanConvert NaNConvertMode
infConvert InfConvertMode
bigIntConvert BigIntConvertMode
time TimeMode
timeTag EncTagMode
indefLength IndefLengthMode
nilContainers NilContainersMode
tagsMd TagsMode
omitEmpty OmitEmptyMode
stringType StringMode
stringMajorType cborType
fieldName FieldNameMode
}
var defaultEncMode, _ = EncOptions{}.encMode()
// These four decoding modes are used by getMarshalerDecMode.
// maxNestedLevels, maxArrayElements, and maxMapPairs are
// set to max allowed limits to avoid rejecting Marshaler
// output that would have been the allowable output of a
// non-Marshaler object that exceeds default limits.
var (
marshalerForbidIndefLengthForbidTagsDecMode = decMode{
maxNestedLevels: maxMaxNestedLevels,
maxArrayElements: maxMaxArrayElements,
maxMapPairs: maxMaxMapPairs,
indefLength: IndefLengthForbidden,
tagsMd: TagsForbidden,
}
marshalerAllowIndefLengthForbidTagsDecMode = decMode{
maxNestedLevels: maxMaxNestedLevels,
maxArrayElements: maxMaxArrayElements,
maxMapPairs: maxMaxMapPairs,
indefLength: IndefLengthAllowed,
tagsMd: TagsForbidden,
}
marshalerForbidIndefLengthAllowTagsDecMode = decMode{
maxNestedLevels: maxMaxNestedLevels,
maxArrayElements: maxMaxArrayElements,
maxMapPairs: maxMaxMapPairs,
indefLength: IndefLengthForbidden,
tagsMd: TagsAllowed,
}
marshalerAllowIndefLengthAllowTagsDecMode = decMode{
maxNestedLevels: maxMaxNestedLevels,
maxArrayElements: maxMaxArrayElements,
maxMapPairs: maxMaxMapPairs,
indefLength: IndefLengthAllowed,
tagsMd: TagsAllowed,
}
)
// getMarshalerDecMode returns one of four existing decoding modes
// which can be reused (safe for parallel use) for the purpose of
// checking if data returned by Marshaler is well-formed.
func getMarshalerDecMode(indefLength IndefLengthMode, tagsMd TagsMode) *decMode {
switch {
case indefLength == IndefLengthAllowed && tagsMd == TagsAllowed:
return &marshalerAllowIndefLengthAllowTagsDecMode
case indefLength == IndefLengthAllowed && tagsMd == TagsForbidden:
return &marshalerAllowIndefLengthForbidTagsDecMode
case indefLength == IndefLengthForbidden && tagsMd == TagsAllowed:
return &marshalerForbidIndefLengthAllowTagsDecMode
case indefLength == IndefLengthForbidden && tagsMd == TagsForbidden:
return &marshalerForbidIndefLengthForbidTagsDecMode
default:
// This should never happen, unless we add new options to
// IndefLengthMode or TagsMode without updating this function.
return &decMode{
maxNestedLevels: maxMaxNestedLevels,
maxArrayElements: maxMaxArrayElements,
maxMapPairs: maxMaxMapPairs,
indefLength: indefLength,
tagsMd: tagsMd,
}
}
}
// EncOptions returns user specified options used to create this EncMode.
func (em *encMode) EncOptions() EncOptions {
return EncOptions{
Sort: em.sort,
ShortestFloat: em.shortestFloat,
NaNConvert: em.nanConvert,
InfConvert: em.infConvert,
BigIntConvert: em.bigIntConvert,
Time: em.time,
TimeTag: em.timeTag,
IndefLength: em.indefLength,
NilContainers: em.nilContainers,
TagsMd: em.tagsMd,
OmitEmpty: em.omitEmpty,
String: em.stringType,
FieldName: em.fieldName,
}
}
func (em *encMode) encTagBytes(t reflect.Type) []byte {
if em.tags != nil {
if tagItem := em.tags.getTagItemFromType(t); tagItem != nil {
return tagItem.cborTagNum
}
}
return nil
}
// Marshal returns the CBOR encoding of v using em encoding mode.
//
// See the documentation for Marshal for details.
func (em *encMode) Marshal(v interface{}) ([]byte, error) {
e := getEncoderBuffer()
if err := encode(e, em, reflect.ValueOf(v)); err != nil {
putEncoderBuffer(e)
return nil, err
}
buf := make([]byte, e.Len())
copy(buf, e.Bytes())
putEncoderBuffer(e)
return buf, nil
}
// NewEncoder returns a new encoder that writes to w using em EncMode.
func (em *encMode) NewEncoder(w io.Writer) *Encoder {
return &Encoder{w: w, em: em}
}
type encoderBuffer struct {
bytes.Buffer
scratch [16]byte
}
// encoderBufferPool caches unused encoderBuffer objects for later reuse.
var encoderBufferPool = sync.Pool{
New: func() interface{} {
e := new(encoderBuffer)
e.Grow(32) // TODO: make this configurable
return e
},
}
func getEncoderBuffer() *encoderBuffer {
return encoderBufferPool.Get().(*encoderBuffer)
}
func putEncoderBuffer(e *encoderBuffer) {
e.Reset()
encoderBufferPool.Put(e)
}
type encodeFunc func(e *encoderBuffer, em *encMode, v reflect.Value) error
type isEmptyFunc func(em *encMode, v reflect.Value) (empty bool, err error)
var (
cborFalse = []byte{0xf4}
cborTrue = []byte{0xf5}
cborNil = []byte{0xf6}
cborNaN = []byte{0xf9, 0x7e, 0x00}
cborPositiveInfinity = []byte{0xf9, 0x7c, 0x00}
cborNegativeInfinity = []byte{0xf9, 0xfc, 0x00}
)
func encode(e *encoderBuffer, em *encMode, v reflect.Value) error {
if !v.IsValid() {
// v is zero value
e.Write(cborNil)
return nil
}
vt := v.Type()
f, _ := getEncodeFunc(vt)
if f == nil {
return &UnsupportedTypeError{vt}
}
return f(e, em, v)
}
func encodeBool(e *encoderBuffer, em *encMode, v reflect.Value) error {
if b := em.encTagBytes(v.Type()); b != nil {
e.Write(b)
}
b := cborFalse
if v.Bool() {
b = cborTrue
}
e.Write(b)
return nil
}
func encodeInt(e *encoderBuffer, em *encMode, v reflect.Value) error {
if b := em.encTagBytes(v.Type()); b != nil {
e.Write(b)
}
i := v.Int()
if i >= 0 {
encodeHead(e, byte(cborTypePositiveInt), uint64(i))
return nil
}
i = i*(-1) - 1
encodeHead(e, byte(cborTypeNegativeInt), uint64(i))
return nil
}
func encodeUint(e *encoderBuffer, em *encMode, v reflect.Value) error {
if b := em.encTagBytes(v.Type()); b != nil {
e.Write(b)
}
encodeHead(e, byte(cborTypePositiveInt), v.Uint())
return nil
}
func encodeFloat(e *encoderBuffer, em *encMode, v reflect.Value) error {
if b := em.encTagBytes(v.Type()); b != nil {
e.Write(b)
}
f64 := v.Float()
if math.IsNaN(f64) {
return encodeNaN(e, em, v)
}
if math.IsInf(f64, 0) {
return encodeInf(e, em, v)
}
fopt := em.shortestFloat
if v.Kind() == reflect.Float64 && (fopt == ShortestFloatNone || cannotFitFloat32(f64)) {
// Encode float64
// Don't use encodeFloat64() because it cannot be inlined.
e.scratch[0] = byte(cborTypePrimitives) | byte(27)
binary.BigEndian.PutUint64(e.scratch[1:], math.Float64bits(f64))
e.Write(e.scratch[:9])
return nil
}
f32 := float32(f64)
if fopt == ShortestFloat16 {
var f16 float16.Float16
p := float16.PrecisionFromfloat32(f32)
if p == float16.PrecisionExact {
// Roundtrip float32->float16->float32 test isn't needed.
f16 = float16.Fromfloat32(f32)
} else if p == float16.PrecisionUnknown {
// Try roundtrip float32->float16->float32 to determine if float32 can fit into float16.
f16 = float16.Fromfloat32(f32)
if f16.Float32() == f32 {
p = float16.PrecisionExact
}
}
if p == float16.PrecisionExact {
// Encode float16
// Don't use encodeFloat16() because it cannot be inlined.
e.scratch[0] = byte(cborTypePrimitives) | byte(25)
binary.BigEndian.PutUint16(e.scratch[1:], uint16(f16))
e.Write(e.scratch[:3])
return nil
}
}
// Encode float32
// Don't use encodeFloat32() because it cannot be inlined.
e.scratch[0] = byte(cborTypePrimitives) | byte(26)
binary.BigEndian.PutUint32(e.scratch[1:], math.Float32bits(f32))
e.Write(e.scratch[:5])
return nil
}
func encodeInf(e *encoderBuffer, em *encMode, v reflect.Value) error {
f64 := v.Float()
if em.infConvert == InfConvertFloat16 {
if f64 > 0 {
e.Write(cborPositiveInfinity)
} else {
e.Write(cborNegativeInfinity)
}
return nil
}
if v.Kind() == reflect.Float64 {
return encodeFloat64(e, f64)
}
return encodeFloat32(e, float32(f64))
}
func encodeNaN(e *encoderBuffer, em *encMode, v reflect.Value) error {
switch em.nanConvert {
case NaNConvert7e00:
e.Write(cborNaN)
return nil
case NaNConvertNone:
if v.Kind() == reflect.Float64 {
return encodeFloat64(e, v.Float())
}
f32 := float32NaNFromReflectValue(v)
return encodeFloat32(e, f32)
default: // NaNConvertPreserveSignal, NaNConvertQuiet
if v.Kind() == reflect.Float64 {
f64 := v.Float()
f64bits := math.Float64bits(f64)
if em.nanConvert == NaNConvertQuiet && f64bits&(1<<51) == 0 {
f64bits |= 1 << 51 // Set quiet bit = 1
f64 = math.Float64frombits(f64bits)
}
// The lower 29 bits are dropped when converting from float64 to float32.
if f64bits&0x1fffffff != 0 {
// Encode NaN as float64 because dropped coef bits from float64 to float32 are not all 0s.
return encodeFloat64(e, f64)
}
// Create float32 from float64 manually because float32(f64) always turns on NaN's quiet bits.
sign := uint32(f64bits>>32) & (1 << 31)
exp := uint32(0x7f800000)
coef := uint32((f64bits & 0xfffffffffffff) >> 29)
f32bits := sign | exp | coef
f32 := math.Float32frombits(f32bits)
// The lower 13 bits are dropped when converting from float32 to float16.
if f32bits&0x1fff != 0 {
// Encode NaN as float32 because dropped coef bits from float32 to float16 are not all 0s.
return encodeFloat32(e, f32)
}
// Encode NaN as float16
f16, _ := float16.FromNaN32ps(f32) // Ignore err because it only returns error when f32 is not a NaN.
return encodeFloat16(e, f16)
}
f32 := float32NaNFromReflectValue(v)
f32bits := math.Float32bits(f32)
if em.nanConvert == NaNConvertQuiet && f32bits&(1<<22) == 0 {
f32bits |= 1 << 22 // Set quiet bit = 1
f32 = math.Float32frombits(f32bits)
}
// The lower 13 bits are dropped coef bits when converting from float32 to float16.
if f32bits&0x1fff != 0 {
// Encode NaN as float32 because dropped coef bits from float32 to float16 are not all 0s.
return encodeFloat32(e, f32)
}
f16, _ := float16.FromNaN32ps(f32) // Ignore err because it only returns error when f32 is not a NaN.
return encodeFloat16(e, f16)
}
}
func encodeFloat16(e *encoderBuffer, f16 float16.Float16) error {
e.scratch[0] = byte(cborTypePrimitives) | byte(25)
binary.BigEndian.PutUint16(e.scratch[1:], uint16(f16))
e.Write(e.scratch[:3])
return nil
}
func encodeFloat32(e *encoderBuffer, f32 float32) error {
e.scratch[0] = byte(cborTypePrimitives) | byte(26)
binary.BigEndian.PutUint32(e.scratch[1:], math.Float32bits(f32))
e.Write(e.scratch[:5])
return nil
}
func encodeFloat64(e *encoderBuffer, f64 float64) error {
e.scratch[0] = byte(cborTypePrimitives) | byte(27)
binary.BigEndian.PutUint64(e.scratch[1:], math.Float64bits(f64))
e.Write(e.scratch[:9])