1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
// 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 objects from an input stream.
type Decoder struct {
r io.Reader
buf []byte
d decodeState
scan scanner
err error
}
// 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 }
// 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 interface{}) error {
if dec.err != nil {
return dec.err
}
n, err := dec.readValue()
if err != nil {
return err
}
// 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.
dec.d.init(dec.buf[0:n])
err = dec.d.unmarshal(v)
// Slide rest of data down.
rest := copy(dec.buf, dec.buf[n:])
dec.buf = dec.buf[0:rest]
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)
}
// 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 := 0
var err error
Input:
for {
// Look in the buffer for a new value.
for i, c := range dec.buf[scanp:] {
dec.scan.bytes++
v := dec.scan.step(&dec.scan, int(c))
if v == scanEnd {
scanp += i
break Input
}
// scanEnd is delayed one byte.
// We might block trying to get that byte from src,
// so instead invent a space byte.
if (v == scanEndObject || v == scanEndArray) && dec.scan.step(&dec.scan, ' ') == scanEnd {
scanp += i + 1
break Input
}
if v == scanError {
dec.err = dec.scan.err
return 0, dec.scan.err
}
}
scanp = len(dec.buf)
// 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
}
// Make room to read more into the buffer.
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).
var n int
n, err = dec.r.Read(dec.buf[len(dec.buf):cap(dec.buf)])
dec.buf = dec.buf[0 : len(dec.buf)+n]
}
return scanp, nil
}
func nonSpace(b []byte) bool {
for _, c := range b {
if !isSpace(rune(c)) {
return true
}
}
return false
}
// An Encoder writes JSON objects to an output stream.
type Encoder struct {
w io.Writer
e encodeState
err error
}
// NewEncoder returns a new encoder that writes to w.
func NewEncoder(w io.Writer) *Encoder {
return &Encoder{w: w}
}
// Encode writes the JSON encoding of v to the stream.
//
// See the documentation for Marshal for details about the
// conversion of Go values to JSON.
func (enc *Encoder) Encode(v interface{}) error {
if enc.err != nil {
return enc.err
}
e := newEncodeState()
err := e.marshal(v)
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')
if _, err = enc.w.Write(e.Bytes()); err != nil {
enc.err = err
}
putEncodeState(e)
return err
}
// RawMessage is a raw encoded JSON object.
// 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) {
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)
|
