go-json/decode.go

170 lines
3.8 KiB
Go

package json
import (
"fmt"
"io"
"reflect"
"unsafe"
"github.com/goccy/go-json/internal/decoder"
"github.com/goccy/go-json/internal/errors"
"github.com/goccy/go-json/internal/runtime"
)
type Decoder struct {
s *decoder.Stream
}
const (
nul = '\000'
)
type emptyInterface struct {
typ *runtime.Type
ptr unsafe.Pointer
}
func unmarshal(data []byte, v interface{}, optFuncs ...DecodeOptionFunc) error {
src := make([]byte, len(data)+1) // append nul byte to the end
copy(src, data)
header := (*emptyInterface)(unsafe.Pointer(&v))
if err := validateType(header.typ, uintptr(header.ptr)); err != nil {
return err
}
dec, err := decoder.CompileToGetDecoder(header.typ)
if err != nil {
return err
}
cursor, err := dec.Decode(src, 0, 0, header.ptr)
if err != nil {
return err
}
return validateEndBuf(src, cursor)
}
func unmarshalNoEscape(data []byte, v interface{}) error {
src := make([]byte, len(data)+1) // append nul byte to the end
copy(src, data)
header := (*emptyInterface)(unsafe.Pointer(&v))
if err := validateType(header.typ, uintptr(header.ptr)); err != nil {
return err
}
dec, err := decoder.CompileToGetDecoder(header.typ)
if err != nil {
return err
}
cursor, err := dec.Decode(src, 0, 0, noescape(header.ptr))
if err != nil {
return err
}
return validateEndBuf(src, cursor)
}
func validateEndBuf(src []byte, cursor int64) error {
for {
switch src[cursor] {
case ' ', '\t', '\n', '\r':
cursor++
continue
case nul:
return nil
}
return errors.ErrSyntax(
fmt.Sprintf("invalid character '%c' after top-level value", src[cursor]),
cursor+1,
)
}
}
//nolint:staticcheck
//go:nosplit
func noescape(p unsafe.Pointer) unsafe.Pointer {
x := uintptr(p)
return unsafe.Pointer(x ^ 0)
}
func validateType(typ *runtime.Type, p uintptr) error {
if typ == nil || typ.Kind() != reflect.Ptr || p == 0 {
return &InvalidUnmarshalError{Type: runtime.RType2Type(typ)}
}
return nil
}
// NewDecoder returns a new decoder that reads from r.
//
// The decoder introduces its own buffering and may
// read data from r beyond the JSON values requested.
func NewDecoder(r io.Reader) *Decoder {
s := decoder.NewStream(r)
return &Decoder{
s: s,
}
}
// Buffered returns a reader of the data remaining in the Decoder's
// buffer. The reader is valid until the next call to Decode.
func (d *Decoder) Buffered() io.Reader {
return d.s.Buffered()
}
// Decode reads the next JSON-encoded value from its
// input and stores it in the value pointed to by v.
//
// See the documentation for Unmarshal for details about
// the conversion of JSON into a Go value.
func (d *Decoder) Decode(v interface{}) error {
header := (*emptyInterface)(unsafe.Pointer(&v))
typ := header.typ
ptr := uintptr(header.ptr)
typeptr := uintptr(unsafe.Pointer(typ))
// noescape trick for header.typ ( reflect.*rtype )
copiedType := *(**runtime.Type)(unsafe.Pointer(&typeptr))
if err := validateType(copiedType, ptr); err != nil {
return err
}
dec, err := decoder.CompileToGetDecoder(typ)
if err != nil {
return err
}
if err := d.s.PrepareForDecode(); err != nil {
return err
}
s := d.s
if err := dec.DecodeStream(s, 0, header.ptr); err != nil {
return err
}
s.Reset()
return nil
}
func (d *Decoder) More() bool {
return d.s.More()
}
func (d *Decoder) Token() (Token, error) {
return d.s.Token()
}
// DisallowUnknownFields causes the Decoder to return an error when the destination
// is a struct and the input contains object keys which do not match any
// non-ignored, exported fields in the destination.
func (d *Decoder) DisallowUnknownFields() {
d.s.DisallowUnknownFields = true
}
func (d *Decoder) InputOffset() int64 {
return d.s.TotalOffset()
}
// UseNumber causes the Decoder to unmarshal a number into an interface{} as a
// Number instead of as a float64.
func (d *Decoder) UseNumber() {
d.s.UseNumber = true
}