mirror of
https://github.com/wader/fq.git
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270 lines
6.9 KiB
Go
270 lines
6.9 KiB
Go
package cbor
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// https://en.wikipedia.org/wiki/CBOR
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// https://www.rfc-editor.org/rfc/rfc8949.html
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// TODO: streaming bytes test?
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// TODO: decode some sematic tags
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import (
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"bytes"
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"embed"
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"math/big"
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"strings"
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"github.com/wader/fq/format"
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"github.com/wader/fq/internal/mathex"
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"github.com/wader/fq/pkg/bitio"
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"github.com/wader/fq/pkg/decode"
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"github.com/wader/fq/pkg/interp"
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"github.com/wader/fq/pkg/scalar"
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)
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//go:embed cbor.jq
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//go:embed cbor.md
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var cborFS embed.FS
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func init() {
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interp.RegisterFormat(decode.Format{
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Name: format.CBOR,
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Description: "Concise Binary Object Representation",
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DecodeFn: decodeCBOR,
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Functions: []string{"torepr"},
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})
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interp.RegisterFS(cborFS)
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}
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type majorTypeEntry struct {
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s scalar.Uint
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d func(d *decode.D, shortCount uint64, count uint64) any
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}
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type majorTypeEntries map[uint64]majorTypeEntry
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func (mts majorTypeEntries) MapUint(s scalar.Uint) (scalar.Uint, error) {
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u := s.Actual
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if fe, ok := mts[u]; ok {
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s = fe.s
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s.Actual = u
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}
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return s, nil
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}
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const (
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shortCountVariable8Bit = 24
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shortCountVariable16Bit = 25
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shortCountVariable32Bit = 26
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shortCountVariable64Bit = 27
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shortCountIndefinite = 31
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shortCountSpecialFalse = 20
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shortCountSpecialTrue = 21
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shortCountSpecialNull = 22
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shortCountSpecialUndefined = 23
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shortCountSpecialFloat16Bit = 25
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shortCountSpecialFloat32Bit = 26
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shortCountSpecialFloat64Bit = 27
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)
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var shortCountMap = scalar.UintMapSymStr{
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shortCountVariable8Bit: "8bit",
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shortCountVariable16Bit: "16bit",
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shortCountVariable32Bit: "32bit",
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shortCountVariable64Bit: "64bit",
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shortCountIndefinite: "indefinite",
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}
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var tagMap = scalar.UintMapSymStr{
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0: "date_time",
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1: "epoch_date_time",
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2: "unsigned_bignum",
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3: "negative_bignum",
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4: "decimal_fraction",
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5: "bigfloat",
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21: "base64url",
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22: "base64",
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23: "base16",
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24: "encoded_cbor",
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32: "uri",
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33: "base64url",
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34: "base64",
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36: "mime_message",
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55799: "self_described_cbor",
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}
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const (
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majorTypePositiveInt = 0
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majorTypeNegativeInt = 1
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majorTypeBytes = 2
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majorTypeUTF8 = 3
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majorTypeArray = 4
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majorTypeMap = 5
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majorTypeSematic = 6
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majorTypeSpecialFloat = 7
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)
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const (
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breakMarker = 0xff
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)
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func decodeCBORValue(d *decode.D) any {
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majorTypeMap := majorTypeEntries{
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majorTypePositiveInt: {s: scalar.Uint{Sym: "positive_int"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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d.FieldValueUint("value", count)
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return nil
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}},
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majorTypeNegativeInt: {s: scalar.Uint{Sym: "negative_int"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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n := new(big.Int)
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n.SetUint64(count).Neg(n).Sub(n, mathex.BigIntOne)
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d.FieldValueBigInt("value", n)
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return nil
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}},
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majorTypeBytes: {s: scalar.Uint{Sym: "bytes"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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if shortCount == shortCountIndefinite {
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bb := &bytes.Buffer{}
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d.FieldArray("items", func(d *decode.D) {
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for d.PeekUintBits(8) != breakMarker {
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d.FieldStruct("item", func(d *decode.D) {
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v := decodeCBORValue(d)
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switch v := v.(type) {
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case []byte:
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bb.Write(v)
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default:
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d.Fatalf("non-bytes in bytes stream %v", v)
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}
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})
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}
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})
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d.FieldRootBitBuf("value", bitio.NewBitReader(bb.Bytes(), -1))
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// nil, nested indefinite bytes is not allowed
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return nil
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}
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buf := d.ReadAllBits(d.FieldRawLen("value", int64(count)*8))
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return buf
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}},
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majorTypeUTF8: {s: scalar.Uint{Sym: "utf8"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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if shortCount == shortCountIndefinite {
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sb := &strings.Builder{}
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d.FieldArray("items", func(d *decode.D) {
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for d.PeekUintBits(8) != breakMarker {
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d.FieldStruct("item", func(d *decode.D) {
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v := decodeCBORValue(d)
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switch v := v.(type) {
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case string:
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sb.WriteString(v)
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default:
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d.Fatalf("non-string in string stream %v", v)
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}
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})
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}
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})
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d.FieldValueStr("value", sb.String())
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// nil, nested indefinite string is not allowed
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return nil
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}
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return d.FieldUTF8("value", int(count))
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}},
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majorTypeArray: {s: scalar.Uint{Sym: "array"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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d.FieldArray("elements", func(d *decode.D) {
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for i := uint64(0); true; i++ {
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if shortCount == shortCountIndefinite && d.PeekUintBits(8) == breakMarker {
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break
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} else if i >= count {
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break
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}
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d.FieldStruct("element", func(d *decode.D) { decodeCBORValue(d) })
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}
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})
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if shortCount == shortCountIndefinite {
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d.FieldU8("break")
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}
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return nil
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}},
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majorTypeMap: {s: scalar.Uint{Sym: "map"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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d.FieldArray("pairs", func(d *decode.D) {
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for i := uint64(0); true; i++ {
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if shortCount == shortCountIndefinite && d.PeekUintBits(8) == breakMarker {
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break
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} else if i >= count {
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break
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}
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d.FieldStruct("pair", func(d *decode.D) {
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d.FieldStruct("key", func(d *decode.D) { decodeCBORValue(d) })
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d.FieldStruct("value", func(d *decode.D) { decodeCBORValue(d) })
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})
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}
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})
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if shortCount == shortCountIndefinite {
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d.FieldU8("break")
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}
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return nil
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}},
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majorTypeSematic: {s: scalar.Uint{Sym: "semantic"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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d.FieldValueUint("tag", count, tagMap)
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d.FieldStruct("value", func(d *decode.D) { decodeCBORValue(d) })
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return nil
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}},
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majorTypeSpecialFloat: {s: scalar.Uint{Sym: "special_float"}, d: func(d *decode.D, shortCount uint64, count uint64) any {
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switch shortCount {
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// TODO: 0-19
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case shortCountSpecialFalse:
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d.FieldValueBool("value", false)
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case shortCountSpecialTrue:
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d.FieldValueBool("value", true)
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case shortCountSpecialNull:
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d.FieldValueAny("value", nil)
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case shortCountSpecialUndefined:
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// TODO: undefined
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case 24:
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// TODO: future
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case shortCountSpecialFloat16Bit:
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d.FieldF16("value")
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case shortCountSpecialFloat32Bit:
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d.FieldF32("value")
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case shortCountSpecialFloat64Bit:
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d.FieldF64("value")
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case 28, 29, 30:
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// TODO: future
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}
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return nil
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}},
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}
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typ := d.FieldU3("major_type", majorTypeMap)
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shortCount := d.FieldU5("short_count", shortCountMap)
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count := shortCount
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if typ != majorTypeSpecialFloat {
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switch count {
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// 0-23 value in shortCount
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case shortCountVariable8Bit:
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count = d.FieldU8("variable_count")
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case shortCountVariable16Bit:
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count = d.FieldU16("variable_count")
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case shortCountVariable32Bit:
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count = d.FieldU32("variable_count")
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case shortCountVariable64Bit:
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count = d.FieldU64("variable_count")
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case 28, 29, 30:
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d.Fatalf("incorrect shortCount %d", count)
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}
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}
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if mt, ok := majorTypeMap[typ]; ok {
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if mt.d != nil {
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return mt.d(d, shortCount, count)
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}
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return nil
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}
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panic("unreachable")
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}
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func decodeCBOR(d *decode.D) any {
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decodeCBORValue(d)
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return nil
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}
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