mirror of
https://github.com/autc04/Retro68.git
synced 2024-09-08 20:55:01 +00:00
515 lines
13 KiB
Go
515 lines
13 KiB
Go
// Copyright 2010 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package json
|
|
|
|
import (
|
|
"bytes"
|
|
"errors"
|
|
"io"
|
|
)
|
|
|
|
// A Decoder reads and decodes JSON values from an input stream.
|
|
type Decoder struct {
|
|
r io.Reader
|
|
buf []byte
|
|
d decodeState
|
|
scanp int // start of unread data in buf
|
|
scanned int64 // amount of data already scanned
|
|
scan scanner
|
|
err error
|
|
|
|
tokenState int
|
|
tokenStack []int
|
|
}
|
|
|
|
// 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 {
|
|
return &Decoder{r: r}
|
|
}
|
|
|
|
// UseNumber causes the Decoder to unmarshal a number into an interface{} as a
|
|
// Number instead of as a float64.
|
|
func (dec *Decoder) UseNumber() { dec.d.useNumber = true }
|
|
|
|
// 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 (dec *Decoder) DisallowUnknownFields() { dec.d.disallowUnknownFields = true }
|
|
|
|
// 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 (dec *Decoder) Decode(v any) error {
|
|
if dec.err != nil {
|
|
return dec.err
|
|
}
|
|
|
|
if err := dec.tokenPrepareForDecode(); err != nil {
|
|
return err
|
|
}
|
|
|
|
if !dec.tokenValueAllowed() {
|
|
return &SyntaxError{msg: "not at beginning of value", Offset: dec.InputOffset()}
|
|
}
|
|
|
|
// Read whole value into buffer.
|
|
n, err := dec.readValue()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
dec.d.init(dec.buf[dec.scanp : dec.scanp+n])
|
|
dec.scanp += n
|
|
|
|
// Don't save err from unmarshal into dec.err:
|
|
// the connection is still usable since we read a complete JSON
|
|
// object from it before the error happened.
|
|
err = dec.d.unmarshal(v)
|
|
|
|
// fixup token streaming state
|
|
dec.tokenValueEnd()
|
|
|
|
return err
|
|
}
|
|
|
|
// Buffered returns a reader of the data remaining in the Decoder's
|
|
// buffer. The reader is valid until the next call to Decode.
|
|
func (dec *Decoder) Buffered() io.Reader {
|
|
return bytes.NewReader(dec.buf[dec.scanp:])
|
|
}
|
|
|
|
// readValue reads a JSON value into dec.buf.
|
|
// It returns the length of the encoding.
|
|
func (dec *Decoder) readValue() (int, error) {
|
|
dec.scan.reset()
|
|
|
|
scanp := dec.scanp
|
|
var err error
|
|
Input:
|
|
// help the compiler see that scanp is never negative, so it can remove
|
|
// some bounds checks below.
|
|
for scanp >= 0 {
|
|
|
|
// Look in the buffer for a new value.
|
|
for ; scanp < len(dec.buf); scanp++ {
|
|
c := dec.buf[scanp]
|
|
dec.scan.bytes++
|
|
switch dec.scan.step(&dec.scan, c) {
|
|
case scanEnd:
|
|
// scanEnd is delayed one byte so we decrement
|
|
// the scanner bytes count by 1 to ensure that
|
|
// this value is correct in the next call of Decode.
|
|
dec.scan.bytes--
|
|
break Input
|
|
case scanEndObject, scanEndArray:
|
|
// scanEnd is delayed one byte.
|
|
// We might block trying to get that byte from src,
|
|
// so instead invent a space byte.
|
|
if stateEndValue(&dec.scan, ' ') == scanEnd {
|
|
scanp++
|
|
break Input
|
|
}
|
|
case scanError:
|
|
dec.err = dec.scan.err
|
|
return 0, dec.scan.err
|
|
}
|
|
}
|
|
|
|
// Did the last read have an error?
|
|
// Delayed until now to allow buffer scan.
|
|
if err != nil {
|
|
if err == io.EOF {
|
|
if dec.scan.step(&dec.scan, ' ') == scanEnd {
|
|
break Input
|
|
}
|
|
if nonSpace(dec.buf) {
|
|
err = io.ErrUnexpectedEOF
|
|
}
|
|
}
|
|
dec.err = err
|
|
return 0, err
|
|
}
|
|
|
|
n := scanp - dec.scanp
|
|
err = dec.refill()
|
|
scanp = dec.scanp + n
|
|
}
|
|
return scanp - dec.scanp, nil
|
|
}
|
|
|
|
func (dec *Decoder) refill() error {
|
|
// Make room to read more into the buffer.
|
|
// First slide down data already consumed.
|
|
if dec.scanp > 0 {
|
|
dec.scanned += int64(dec.scanp)
|
|
n := copy(dec.buf, dec.buf[dec.scanp:])
|
|
dec.buf = dec.buf[:n]
|
|
dec.scanp = 0
|
|
}
|
|
|
|
// Grow buffer if not large enough.
|
|
const minRead = 512
|
|
if cap(dec.buf)-len(dec.buf) < minRead {
|
|
newBuf := make([]byte, len(dec.buf), 2*cap(dec.buf)+minRead)
|
|
copy(newBuf, dec.buf)
|
|
dec.buf = newBuf
|
|
}
|
|
|
|
// Read. Delay error for next iteration (after scan).
|
|
n, err := dec.r.Read(dec.buf[len(dec.buf):cap(dec.buf)])
|
|
dec.buf = dec.buf[0 : len(dec.buf)+n]
|
|
|
|
return err
|
|
}
|
|
|
|
func nonSpace(b []byte) bool {
|
|
for _, c := range b {
|
|
if !isSpace(c) {
|
|
return true
|
|
}
|
|
}
|
|
return false
|
|
}
|
|
|
|
// An Encoder writes JSON values to an output stream.
|
|
type Encoder struct {
|
|
w io.Writer
|
|
err error
|
|
escapeHTML bool
|
|
|
|
indentBuf *bytes.Buffer
|
|
indentPrefix string
|
|
indentValue string
|
|
}
|
|
|
|
// NewEncoder returns a new encoder that writes to w.
|
|
func NewEncoder(w io.Writer) *Encoder {
|
|
return &Encoder{w: w, escapeHTML: true}
|
|
}
|
|
|
|
// Encode writes the JSON encoding of v to the stream,
|
|
// followed by a newline character.
|
|
//
|
|
// See the documentation for Marshal for details about the
|
|
// conversion of Go values to JSON.
|
|
func (enc *Encoder) Encode(v any) error {
|
|
if enc.err != nil {
|
|
return enc.err
|
|
}
|
|
e := newEncodeState()
|
|
err := e.marshal(v, encOpts{escapeHTML: enc.escapeHTML})
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
// Terminate each value with a newline.
|
|
// This makes the output look a little nicer
|
|
// when debugging, and some kind of space
|
|
// is required if the encoded value was a number,
|
|
// so that the reader knows there aren't more
|
|
// digits coming.
|
|
e.WriteByte('\n')
|
|
|
|
b := e.Bytes()
|
|
if enc.indentPrefix != "" || enc.indentValue != "" {
|
|
if enc.indentBuf == nil {
|
|
enc.indentBuf = new(bytes.Buffer)
|
|
}
|
|
enc.indentBuf.Reset()
|
|
err = Indent(enc.indentBuf, b, enc.indentPrefix, enc.indentValue)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
b = enc.indentBuf.Bytes()
|
|
}
|
|
if _, err = enc.w.Write(b); err != nil {
|
|
enc.err = err
|
|
}
|
|
encodeStatePool.Put(e)
|
|
return err
|
|
}
|
|
|
|
// SetIndent instructs the encoder to format each subsequent encoded
|
|
// value as if indented by the package-level function Indent(dst, src, prefix, indent).
|
|
// Calling SetIndent("", "") disables indentation.
|
|
func (enc *Encoder) SetIndent(prefix, indent string) {
|
|
enc.indentPrefix = prefix
|
|
enc.indentValue = indent
|
|
}
|
|
|
|
// SetEscapeHTML specifies whether problematic HTML characters
|
|
// should be escaped inside JSON quoted strings.
|
|
// The default behavior is to escape &, <, and > to \u0026, \u003c, and \u003e
|
|
// to avoid certain safety problems that can arise when embedding JSON in HTML.
|
|
//
|
|
// In non-HTML settings where the escaping interferes with the readability
|
|
// of the output, SetEscapeHTML(false) disables this behavior.
|
|
func (enc *Encoder) SetEscapeHTML(on bool) {
|
|
enc.escapeHTML = on
|
|
}
|
|
|
|
// RawMessage is a raw encoded JSON value.
|
|
// It implements Marshaler and Unmarshaler and can
|
|
// be used to delay JSON decoding or precompute a JSON encoding.
|
|
type RawMessage []byte
|
|
|
|
// MarshalJSON returns m as the JSON encoding of m.
|
|
func (m RawMessage) MarshalJSON() ([]byte, error) {
|
|
if m == nil {
|
|
return []byte("null"), nil
|
|
}
|
|
return m, nil
|
|
}
|
|
|
|
// UnmarshalJSON sets *m to a copy of data.
|
|
func (m *RawMessage) UnmarshalJSON(data []byte) error {
|
|
if m == nil {
|
|
return errors.New("json.RawMessage: UnmarshalJSON on nil pointer")
|
|
}
|
|
*m = append((*m)[0:0], data...)
|
|
return nil
|
|
}
|
|
|
|
var _ Marshaler = (*RawMessage)(nil)
|
|
var _ Unmarshaler = (*RawMessage)(nil)
|
|
|
|
// A Token holds a value of one of these types:
|
|
//
|
|
// Delim, for the four JSON delimiters [ ] { }
|
|
// bool, for JSON booleans
|
|
// float64, for JSON numbers
|
|
// Number, for JSON numbers
|
|
// string, for JSON string literals
|
|
// nil, for JSON null
|
|
//
|
|
type Token any
|
|
|
|
const (
|
|
tokenTopValue = iota
|
|
tokenArrayStart
|
|
tokenArrayValue
|
|
tokenArrayComma
|
|
tokenObjectStart
|
|
tokenObjectKey
|
|
tokenObjectColon
|
|
tokenObjectValue
|
|
tokenObjectComma
|
|
)
|
|
|
|
// advance tokenstate from a separator state to a value state
|
|
func (dec *Decoder) tokenPrepareForDecode() error {
|
|
// Note: Not calling peek before switch, to avoid
|
|
// putting peek into the standard Decode path.
|
|
// peek is only called when using the Token API.
|
|
switch dec.tokenState {
|
|
case tokenArrayComma:
|
|
c, err := dec.peek()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if c != ',' {
|
|
return &SyntaxError{"expected comma after array element", dec.InputOffset()}
|
|
}
|
|
dec.scanp++
|
|
dec.tokenState = tokenArrayValue
|
|
case tokenObjectColon:
|
|
c, err := dec.peek()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if c != ':' {
|
|
return &SyntaxError{"expected colon after object key", dec.InputOffset()}
|
|
}
|
|
dec.scanp++
|
|
dec.tokenState = tokenObjectValue
|
|
}
|
|
return nil
|
|
}
|
|
|
|
func (dec *Decoder) tokenValueAllowed() bool {
|
|
switch dec.tokenState {
|
|
case tokenTopValue, tokenArrayStart, tokenArrayValue, tokenObjectValue:
|
|
return true
|
|
}
|
|
return false
|
|
}
|
|
|
|
func (dec *Decoder) tokenValueEnd() {
|
|
switch dec.tokenState {
|
|
case tokenArrayStart, tokenArrayValue:
|
|
dec.tokenState = tokenArrayComma
|
|
case tokenObjectValue:
|
|
dec.tokenState = tokenObjectComma
|
|
}
|
|
}
|
|
|
|
// A Delim is a JSON array or object delimiter, one of [ ] { or }.
|
|
type Delim rune
|
|
|
|
func (d Delim) String() string {
|
|
return string(d)
|
|
}
|
|
|
|
// Token returns the next JSON token in the input stream.
|
|
// At the end of the input stream, Token returns nil, io.EOF.
|
|
//
|
|
// Token guarantees that the delimiters [ ] { } it returns are
|
|
// properly nested and matched: if Token encounters an unexpected
|
|
// delimiter in the input, it will return an error.
|
|
//
|
|
// The input stream consists of basic JSON values—bool, string,
|
|
// number, and null—along with delimiters [ ] { } of type Delim
|
|
// to mark the start and end of arrays and objects.
|
|
// Commas and colons are elided.
|
|
func (dec *Decoder) Token() (Token, error) {
|
|
for {
|
|
c, err := dec.peek()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
switch c {
|
|
case '[':
|
|
if !dec.tokenValueAllowed() {
|
|
return dec.tokenError(c)
|
|
}
|
|
dec.scanp++
|
|
dec.tokenStack = append(dec.tokenStack, dec.tokenState)
|
|
dec.tokenState = tokenArrayStart
|
|
return Delim('['), nil
|
|
|
|
case ']':
|
|
if dec.tokenState != tokenArrayStart && dec.tokenState != tokenArrayComma {
|
|
return dec.tokenError(c)
|
|
}
|
|
dec.scanp++
|
|
dec.tokenState = dec.tokenStack[len(dec.tokenStack)-1]
|
|
dec.tokenStack = dec.tokenStack[:len(dec.tokenStack)-1]
|
|
dec.tokenValueEnd()
|
|
return Delim(']'), nil
|
|
|
|
case '{':
|
|
if !dec.tokenValueAllowed() {
|
|
return dec.tokenError(c)
|
|
}
|
|
dec.scanp++
|
|
dec.tokenStack = append(dec.tokenStack, dec.tokenState)
|
|
dec.tokenState = tokenObjectStart
|
|
return Delim('{'), nil
|
|
|
|
case '}':
|
|
if dec.tokenState != tokenObjectStart && dec.tokenState != tokenObjectComma {
|
|
return dec.tokenError(c)
|
|
}
|
|
dec.scanp++
|
|
dec.tokenState = dec.tokenStack[len(dec.tokenStack)-1]
|
|
dec.tokenStack = dec.tokenStack[:len(dec.tokenStack)-1]
|
|
dec.tokenValueEnd()
|
|
return Delim('}'), nil
|
|
|
|
case ':':
|
|
if dec.tokenState != tokenObjectColon {
|
|
return dec.tokenError(c)
|
|
}
|
|
dec.scanp++
|
|
dec.tokenState = tokenObjectValue
|
|
continue
|
|
|
|
case ',':
|
|
if dec.tokenState == tokenArrayComma {
|
|
dec.scanp++
|
|
dec.tokenState = tokenArrayValue
|
|
continue
|
|
}
|
|
if dec.tokenState == tokenObjectComma {
|
|
dec.scanp++
|
|
dec.tokenState = tokenObjectKey
|
|
continue
|
|
}
|
|
return dec.tokenError(c)
|
|
|
|
case '"':
|
|
if dec.tokenState == tokenObjectStart || dec.tokenState == tokenObjectKey {
|
|
var x string
|
|
old := dec.tokenState
|
|
dec.tokenState = tokenTopValue
|
|
err := dec.Decode(&x)
|
|
dec.tokenState = old
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
dec.tokenState = tokenObjectColon
|
|
return x, nil
|
|
}
|
|
fallthrough
|
|
|
|
default:
|
|
if !dec.tokenValueAllowed() {
|
|
return dec.tokenError(c)
|
|
}
|
|
var x any
|
|
if err := dec.Decode(&x); err != nil {
|
|
return nil, err
|
|
}
|
|
return x, nil
|
|
}
|
|
}
|
|
}
|
|
|
|
func (dec *Decoder) tokenError(c byte) (Token, error) {
|
|
var context string
|
|
switch dec.tokenState {
|
|
case tokenTopValue:
|
|
context = " looking for beginning of value"
|
|
case tokenArrayStart, tokenArrayValue, tokenObjectValue:
|
|
context = " looking for beginning of value"
|
|
case tokenArrayComma:
|
|
context = " after array element"
|
|
case tokenObjectKey:
|
|
context = " looking for beginning of object key string"
|
|
case tokenObjectColon:
|
|
context = " after object key"
|
|
case tokenObjectComma:
|
|
context = " after object key:value pair"
|
|
}
|
|
return nil, &SyntaxError{"invalid character " + quoteChar(c) + context, dec.InputOffset()}
|
|
}
|
|
|
|
// More reports whether there is another element in the
|
|
// current array or object being parsed.
|
|
func (dec *Decoder) More() bool {
|
|
c, err := dec.peek()
|
|
return err == nil && c != ']' && c != '}'
|
|
}
|
|
|
|
func (dec *Decoder) peek() (byte, error) {
|
|
var err error
|
|
for {
|
|
for i := dec.scanp; i < len(dec.buf); i++ {
|
|
c := dec.buf[i]
|
|
if isSpace(c) {
|
|
continue
|
|
}
|
|
dec.scanp = i
|
|
return c, nil
|
|
}
|
|
// buffer has been scanned, now report any error
|
|
if err != nil {
|
|
return 0, err
|
|
}
|
|
err = dec.refill()
|
|
}
|
|
}
|
|
|
|
// InputOffset returns the input stream byte offset of the current decoder position.
|
|
// The offset gives the location of the end of the most recently returned token
|
|
// and the beginning of the next token.
|
|
func (dec *Decoder) InputOffset() int64 {
|
|
return dec.scanned + int64(dec.scanp)
|
|
}
|