/
intern.go
151 lines (122 loc) · 2.93 KB
/
intern.go
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
package ljpack
import (
"fmt"
"math"
"reflect"
"github.com/fffonion/ljpack/ljpcode"
)
const (
minInternedStringLen = 3
maxDictLen = math.MaxUint16
)
//------------------------------------------------------------------------------
func encodeInternedInterfaceValue(e *Encoder, v reflect.Value) error {
if v.IsNil() {
return e.EncodeNil()
}
v = v.Elem()
if v.Kind() == reflect.String {
return e.encodeInternedString(v.String(), true)
}
return e.EncodeValue(v)
}
func encodeInternedStringValue(e *Encoder, v reflect.Value) error {
return e.encodeInternedString(v.String(), true)
}
func (e *Encoder) encodeInternedString(s string, intern bool) error {
// Interned string takes at least 3 bytes. Plain string 1 byte + string len.
if len(s) >= minInternedStringLen {
if idx, ok := e.dict[s]; ok {
return e.encodeInternedStringIndex(idx)
}
if intern && len(e.dict) < maxDictLen {
if e.dict == nil {
e.dict = make(map[string]int)
}
idx := len(e.dict)
e.dict[s] = idx
}
}
return e.encodeNormalString(s)
}
func (e *Encoder) encodeInternedStringIndex(idx int) error {
e.buf = e.buf[:1]
e.buf[0] = ljpcode.StringInterned
err := e.write(e.buf)
if err != nil {
return err
}
if uint64(idx) <= math.MaxUint32 {
return e.u124(uint32(idx))
}
return fmt.Errorf("ljpack: interned string index=%d is too large", idx)
}
//------------------------------------------------------------------------------
func decodeInternedInterfaceValue(d *Decoder, v reflect.Value) error {
s, err := d.decodeInternedString(true)
if err == nil {
v.Set(reflect.ValueOf(s))
return nil
}
if err != nil {
if _, ok := err.(unexpectedCodeError); !ok {
return err
}
}
// if err := d.s.UnreadByte(); err != nil {
// return err
// }
return decodeInterfaceValue(d, v)
}
func decodeInternedStringValue(d *Decoder, v reflect.Value) error {
s, err := d.decodeInternedString(true)
if err != nil {
return err
}
v.SetString(s)
return nil
}
func (d *Decoder) decodeInternedString(intern bool) (string, error) {
c, err := d.readCode()
if err != nil {
return "", err
}
if c == ljpcode.StringInterned {
n, err := d.u124()
if err != nil {
return "", err
}
return d.internedStringAtIndex(int(n))
}
if ljpcode.IsString(c) {
err = d.s.UnreadByte()
if err != nil {
return "", err
}
return d.string()
}
return "", unexpectedCodeError{
code: c,
hint: "interned string",
}
}
func (d *Decoder) internedStringAtIndex(idx int) (string, error) {
if idx >= len(d.dict) {
err := fmt.Errorf("ljpack: interned string at index=%d does not exist", idx)
return "", err
}
return d.dict[idx], nil
}
func (d *Decoder) decodeInternedStringWithLen(n int, intern bool) (string, error) {
if n <= 0 {
return "", nil
}
s, err := d.stringWithLen(n)
if err != nil {
return "", err
}
if intern && len(s) >= minInternedStringLen && len(d.dict) < maxDictLen {
d.dict = append(d.dict, s)
}
return s, nil
}