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
|
// Copyright 2009 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 strconv
import "errors"
// ErrRange indicates that a value is out of range for the target type.
var ErrRange = errors.New("value out of range")
// ErrSyntax indicates that a value does not have the right syntax for the target type.
var ErrSyntax = errors.New("invalid syntax")
// A NumError records a failed conversion.
type NumError struct {
Func string // the failing function (ParseBool, ParseInt, ParseUint, ParseFloat)
Num string // the input
Err error // the reason the conversion failed (ErrRange, ErrSyntax)
}
func (e *NumError) Error() string {
return "strconv." + e.Func + ": " + `parsing "` + e.Num + `": ` + e.Err.Error()
}
func syntaxError(fn, str string) *NumError {
return &NumError{fn, str, ErrSyntax}
}
func rangeError(fn, str string) *NumError {
return &NumError{fn, str, ErrRange}
}
const intSize = 32 << uint(^uint(0)>>63)
const IntSize = intSize // number of bits in int, uint (32 or 64)
// Return the first number n such that n*base >= 1<<64.
func cutoff64(base int) uint64 {
if base < 2 {
return 0
}
return (1<<64-1)/uint64(base) + 1
}
// ParseUint is like ParseInt but for unsigned numbers.
func ParseUint(s string, b int, bitSize int) (n uint64, err error) {
var cutoff, maxVal uint64
if bitSize == 0 {
bitSize = int(IntSize)
}
s0 := s
switch {
case len(s) < 1:
err = ErrSyntax
goto Error
case 2 <= b && b <= 36:
// valid base; nothing to do
case b == 0:
// Look for octal, hex prefix.
switch {
case s[0] == '0' && len(s) > 1 && (s[1] == 'x' || s[1] == 'X'):
b = 16
s = s[2:]
if len(s) < 1 {
err = ErrSyntax
goto Error
}
case s[0] == '0':
b = 8
default:
b = 10
}
default:
err = errors.New("invalid base " + Itoa(b))
goto Error
}
n = 0
cutoff = cutoff64(b)
maxVal = 1<<uint(bitSize) - 1
for i := 0; i < len(s); i++ {
var v byte
d := s[i]
switch {
case '0' <= d && d <= '9':
v = d - '0'
case 'a' <= d && d <= 'z':
v = d - 'a' + 10
case 'A' <= d && d <= 'Z':
v = d - 'A' + 10
default:
n = 0
err = ErrSyntax
goto Error
}
if int(v) >= b {
n = 0
err = ErrSyntax
goto Error
}
if n >= cutoff {
// n*b overflows
n = 1<<64 - 1
err = ErrRange
goto Error
}
n *= uint64(b)
n1 := n + uint64(v)
if n1 < n || n1 > maxVal {
// n+v overflows
n = 1<<64 - 1
err = ErrRange
goto Error
}
n = n1
}
return n, nil
Error:
return n, &NumError{"ParseUint", s0, err}
}
// ParseInt interprets a string s in the given base (2 to 36) and
// returns the corresponding value i. If base == 0, the base is
// implied by the string's prefix: base 16 for "0x", base 8 for
// "0", and base 10 otherwise.
//
// The bitSize argument specifies the integer type
// that the result must fit into. Bit sizes 0, 8, 16, 32, and 64
// correspond to int, int8, int16, int32, and int64.
//
// The errors that ParseInt returns have concrete type *NumError
// and include err.Num = s. If s is empty or contains invalid
// digits, err.Error = ErrSyntax; if the value corresponding
// to s cannot be represented by a signed integer of the
// given size, err.Error = ErrRange.
func ParseInt(s string, base int, bitSize int) (i int64, err error) {
const fnParseInt = "ParseInt"
if bitSize == 0 {
bitSize = int(IntSize)
}
// Empty string bad.
if len(s) == 0 {
return 0, syntaxError(fnParseInt, s)
}
// Pick off leading sign.
s0 := s
neg := false
if s[0] == '+' {
s = s[1:]
} else if s[0] == '-' {
neg = true
s = s[1:]
}
// Convert unsigned and check range.
var un uint64
un, err = ParseUint(s, base, bitSize)
if err != nil && err.(*NumError).Err != ErrRange {
err.(*NumError).Func = fnParseInt
err.(*NumError).Num = s0
return 0, err
}
cutoff := uint64(1 << uint(bitSize-1))
if !neg && un >= cutoff {
return int64(cutoff - 1), rangeError(fnParseInt, s0)
}
if neg && un > cutoff {
return -int64(cutoff), rangeError(fnParseInt, s0)
}
n := int64(un)
if neg {
n = -n
}
return n, nil
}
// Atoi is shorthand for ParseInt(s, 10, 0).
func Atoi(s string) (i int, err error) {
i64, err := ParseInt(s, 10, 0)
return int(i64), err
}
|
