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-rw-r--r--src/encoding/json/stream.go515
1 files changed, 515 insertions, 0 deletions
diff --git a/src/encoding/json/stream.go b/src/encoding/json/stream.go
new file mode 100644
index 0000000..1442ef2
--- /dev/null
+++ b/src/encoding/json/stream.go
@@ -0,0 +1,515 @@
+// 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()
+ defer encodeStatePool.Put(e)
+
+ 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
+ }
+ 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)
+}
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