forked from aws/aws-dax-go
/
decimal.go
187 lines (160 loc) · 3.82 KB
/
decimal.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
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
/*
Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License").
You may not use this file except in compliance with the License.
A copy of the License is located at
http://www.apache.org/licenses/LICENSE-2.0
or in the "license" file accompanying this file. This file is distributed
on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
express or implied. See the License for the specific language governing
permissions and limitations under the License.
*/
package cbor
import (
"math/big"
"strconv"
"strings"
)
// Decimal represents an arbitrary-precision signed decimal number. It consists
// of an arbitrary precision integer unscaled value and a scale. If zero or
// positive, the scale is the number of digits to the right of the decimal
// point. If negative, the unscaled value of the number is multiplied by ten to
// the power of the negation of the scale: unscaled * (10 ** -scale).
type Decimal struct {
value big.Int
scale int
}
func NewDecimal(unscaled *big.Int, scale int) *Decimal {
return new(Decimal).SetIntScale(unscaled, scale)
}
func (d *Decimal) SetString(s string) (*Decimal, bool) {
if len(s) == 0 {
return nil, false
}
var exp int64
var err error
if sep := strings.IndexAny(s, "Ee"); sep >= 0 {
exp, err = strconv.ParseInt(s[sep+1:], 10, 32)
if err != nil {
return nil, false
}
s = s[:sep]
}
var v big.Int
dot := strings.LastIndexByte(s, '.')
if dot < 0 {
_, ok := v.SetString(s, 10)
if !ok {
return nil, false
}
d.value.Set(&v)
d.scale = int(-exp)
return d, true
}
if signCh := strings.IndexAny(s, "+-"); signCh > 0 {
// Optional sign must be the first char.
return nil, false
}
exp -= int64(len(s) - dot - 1)
_, ok := v.SetString(s[:dot]+s[dot+1:], 10)
if !ok {
return nil, false
}
d.value.Set(&v)
d.scale = int(-exp)
return d, true
}
func (d *Decimal) String() string {
if d.scale == 0 {
return d.value.String()
}
var buf []byte
buf = d.value.Append(buf, 10)
buf = append(buf, 'E')
buf = strconv.AppendInt(buf, -int64(d.scale), 10)
return string(buf)
}
func (d *Decimal) Scale() int {
return d.scale
}
func (d *Decimal) Unscaled() *big.Int {
return &d.value
}
func (d *Decimal) SetInt(v *big.Int) *Decimal {
d.value.Set(v)
return d
}
func (d *Decimal) SetScale(scale int) *Decimal {
d.scale = scale
return d
}
func (d *Decimal) SetIntScale(unscaled *big.Int, scale int) *Decimal {
d.value.Set(unscaled)
d.scale = scale
return d
}
func (r *Reader) ReadDecimal() (*Decimal, error) {
hdr, value, err := r.readTypeHeader()
if err != nil {
return nil, err
}
switch hdr & MajorTypeMask {
case PosInt:
v := new(big.Int).SetUint64(value)
return NewDecimal(v, 0), nil
case NegInt:
v := new(big.Int)
v.SetUint64(value)
v.Not(v)
return NewDecimal(v, 0), nil
case Tag:
// TODO skip other tags.
switch int(value) {
case TagPosBigInt:
v, err := r.readBigInt(0)
if err == nil {
return NewDecimal(v, 0), nil
}
return nil, err
case TagNegBigInt:
v, err := r.readBigInt(-1)
if err == nil {
return NewDecimal(v, 0), nil
}
return nil, err
case TagDecimal:
size, err := r.ReadArrayLength()
if err == nil && size == 2 {
var scale int
var v *big.Int
scale, err = r.ReadInt()
if err == nil {
v, err = r.ReadBigInt()
}
if err == nil {
return NewDecimal(v, -scale), nil
}
}
if err != nil {
return nil, err
}
}
case Simple:
// FIXME: convertible floats.
}
return nil, ErrNaN
}
func (w *Writer) WriteDecimal(value *Decimal) (err error) {
err = w.write(byte(Tag | TagDecimal))
if err != nil {
return err
}
err = w.WriteArrayHeader(2)
if err == nil {
err = w.WriteInt(-value.Scale())
}
if err == nil {
err = w.WriteBigInt(value.Unscaled())
}
return
}