168 lines
3.2 KiB
Go
168 lines
3.2 KiB
Go
package types
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import (
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"encoding/json"
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"fmt"
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"io"
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"math/big"
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cbor "github.com/ipfs/go-ipld-cbor"
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"github.com/polydawn/refmt/obj/atlas"
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cbg "github.com/whyrusleeping/cbor-gen"
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"golang.org/x/xerrors"
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)
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const BigIntMaxSerializedLen = 128 // is this big enough? or too big?
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func init() {
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cbor.RegisterCborType(atlas.BuildEntry(BigInt{}).UseTag(2).Transform().
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TransformMarshal(atlas.MakeMarshalTransformFunc(
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func(i BigInt) ([]byte, error) {
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if i.Int == nil {
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return []byte{}, nil
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}
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return i.Bytes(), nil
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})).
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TransformUnmarshal(atlas.MakeUnmarshalTransformFunc(
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func(x []byte) (BigInt, error) {
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return BigFromBytes(x), nil
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})).
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Complete())
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}
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var EmptyInt = BigInt{}
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type BigInt struct {
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*big.Int
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}
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func NewInt(i uint64) BigInt {
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return BigInt{big.NewInt(0).SetUint64(i)}
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}
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func BigFromBytes(b []byte) BigInt {
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i := big.NewInt(0).SetBytes(b)
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return BigInt{i}
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}
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func BigFromString(s string) (BigInt, error) {
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v, ok := big.NewInt(0).SetString(s, 10)
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if !ok {
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return BigInt{}, fmt.Errorf("failed to parse string as a big int")
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}
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return BigInt{v}, nil
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}
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func BigMul(a, b BigInt) BigInt {
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return BigInt{big.NewInt(0).Mul(a.Int, b.Int)}
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}
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func BigDiv(a, b BigInt) BigInt {
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return BigInt{big.NewInt(0).Div(a.Int, b.Int)}
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}
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func BigAdd(a, b BigInt) BigInt {
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return BigInt{big.NewInt(0).Add(a.Int, b.Int)}
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}
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func BigSub(a, b BigInt) BigInt {
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return BigInt{big.NewInt(0).Sub(a.Int, b.Int)}
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}
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func BigCmp(a, b BigInt) int {
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return a.Int.Cmp(b.Int)
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}
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func (bi *BigInt) Nil() bool {
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return bi.Int == nil
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}
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func (bi *BigInt) MarshalJSON() ([]byte, error) {
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return json.Marshal(bi.String())
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}
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func (bi *BigInt) UnmarshalJSON(b []byte) error {
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var s string
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if err := json.Unmarshal(b, &s); err != nil {
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return err
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}
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i, ok := big.NewInt(0).SetString(s, 10)
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if !ok {
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if string(s) == "<nil>" {
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return nil
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}
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return xerrors.Errorf("failed to parse bigint string: '%s'", string(b))
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}
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bi.Int = i
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return nil
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}
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func (bi *BigInt) MarshalCBOR(w io.Writer) error {
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if bi.Int == nil {
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zero := NewInt(0)
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return zero.MarshalCBOR(w)
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}
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tag := uint64(^(bi.Sign()|1)+6) >> 1
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header := cbg.CborEncodeMajorType(cbg.MajTag, tag)
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if _, err := w.Write(header); err != nil {
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return err
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}
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b := bi.Bytes()
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header = cbg.CborEncodeMajorType(cbg.MajByteString, uint64(len(b)))
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if _, err := w.Write(header); err != nil {
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return err
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}
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if _, err := w.Write(b); err != nil {
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return err
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}
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return nil
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}
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func (bi *BigInt) UnmarshalCBOR(br io.Reader) error {
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maj, extra, err := cbg.CborReadHeader(br)
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if err != nil {
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return err
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}
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if maj != cbg.MajTag && extra != 2 && extra != 3 {
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return fmt.Errorf("cbor input for big int was not a tagged big int")
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}
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minus := extra & 1
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maj, extra, err = cbg.CborReadHeader(br)
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if err != nil {
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return err
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}
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if maj != cbg.MajByteString {
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return fmt.Errorf("cbor input for big int was not a tagged byte string")
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}
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if extra > BigIntMaxSerializedLen {
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return fmt.Errorf("big integer byte array too long")
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}
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buf := make([]byte, extra)
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if _, err := io.ReadFull(br, buf); err != nil {
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return err
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}
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bi.Int = big.NewInt(0).SetBytes(buf)
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if minus > 0 {
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bi.Int.Neg(bi.Int)
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}
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return nil
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}
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