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
|
package tre
import (
"fmt"
"strings"
)
type CharBlock struct {
From []byte
To []byte
}
type cpRange struct {
from rune
to rune
}
func (b *CharBlock) String() string {
var s strings.Builder
fmt.Fprint(&s, "<")
fmt.Fprintf(&s, "%X", b.From[0])
for i := 1; i < len(b.From); i++ {
fmt.Fprintf(&s, " %X", b.From[i])
}
fmt.Fprint(&s, "..")
fmt.Fprintf(&s, "%X", b.To[0])
for i := 1; i < len(b.To); i++ {
fmt.Fprintf(&s, " %X", b.To[i])
}
fmt.Fprint(&s, ">")
return s.String()
}
func GenCharBlocks(from, to rune) ([]*CharBlock, error) {
rs, err := splitCodePoint(from, to)
if err != nil {
return nil, err
}
blks := make([]*CharBlock, len(rs))
for i, r := range rs {
blks[i] = &CharBlock{
From: []byte(string(r.from)),
To: []byte(string(r.to)),
}
}
return blks, nil
}
/// `splitCodePoint` splits a code point range represented by <from..to> into
/// some blocks. The code points that the block contains will be a continuous
/// byte sequence when encoded into UTF-8. For instance, this function splits
/// <U+0000..U+07FF> into <U+0000..U+007F> and <U+0080..U+07FF> because
/// <U+0000..U+07FF> is continuous on the code point but non-continuous in the
/// UTF-8 byte sequence (In UTF-8, <U+0000..U+007F> is encoded <00..7F>, and
/// <U+0080..U+07FF> is encoded <C2 80..DF BF>).
///
/// The blocks don't contain surrogate code points <U+D800..U+DFFF> because byte
/// sequences encoding them are ill-formed in UTF-8. For instance,
/// <U+D000..U+FFFF> is split into <U+D000..U+D7FF> and <U+E000..U+FFFF>.
/// However, when `from` or `to` itself is the surrogate code point, this
/// function returns an error.
func splitCodePoint(from, to rune) ([]*cpRange, error) {
if from > to {
return nil, fmt.Errorf(
"code point range must be from <= to: U+%X..U+%X",
from,
to,
)
}
if from < 0x0000 || from > 0x10ffff || to < 0x0000 || to > 0x10ffff {
return nil, fmt.Errorf(
"code point must be >=U+0000 and <=U+10FFFF:" +
"U+%X..U+%X",
from,
to,
)
}
// https://www.unicode.org/versions/Unicode13.0.0/ch03.pdf
// > 3.9 Unicode Encoding Forms
// > UTF-8 D92
// > Because surrogate code points are not Unicode scalar values,
// > any UTF-8 byte sequence that would otherwise
// > map to code points U+D800..U+DFFF is ill-formed.
if from >= 0xd800 && from <= 0xdfff || to >= 0xd800 && to <= 0xdfff {
return nil, fmt.Errorf(
"surrogate code points U+D800..U+DFFF " +
"are not allowed in UTF-8: U+%X..U+%X",
from,
to,
)
}
in := &cpRange{
from: from,
to: to,
}
var rs []*cpRange
for in.from <= in.to {
r := &cpRange{
from: in.from,
to: in.to,
}
// https://www.unicode.org/versions/Unicode13.0.0/ch03.pdf
// > 3.9 Unicode Encoding Forms
// > UTF-8 Table 3-7.
// > Well-Formed UTF-8 Byte Sequences
switch {
case in.from <= 0x007f && in.to > 0x007f:
r.to = 0x007f
case in.from <= 0x07ff && in.to > 0x07ff:
r.to = 0x07ff
case in.from <= 0x0fff && in.to > 0x0fff:
r.to = 0x0fff
case in.from <= 0xcfff && in.to > 0xcfff:
r.to = 0xcfff
case in.from <= 0xd7ff && in.to > 0xd7ff:
r.to = 0xd7ff
case in.from <= 0xffff && in.to > 0xffff:
r.to = 0xffff
case in.from <= 0x3ffff && in.to > 0x3ffff:
r.to = 0x3ffff
case in.from <= 0xfffff && in.to > 0xfffff:
r.to = 0xfffff
}
rs = append(rs, r)
in.from = r.to + 1
// Skip surrogate code points U+D800..U+DFFF.
if in.from >= 0xd800 && in.from <= 0xdfff {
in.from = 0xe000
}
}
return rs, nil
}
func Main() {
}
|
