/usr/share/gocode/src/golang.org/x/text/internal/colltab/trie.go is in golang-golang-x-text-dev 0.0~git20170627.0.6353ef0-1ubuntu2.
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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 | // Copyright 2012 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.
// The trie in this file is used to associate the first full character in an
// UTF-8 string to a collation element. All but the last byte in a UTF-8 byte
// sequence are used to lookup offsets in the index table to be used for the
// next byte. The last byte is used to index into a table of collation elements.
// For a full description, see go.text/collate/build/trie.go.
package colltab
const blockSize = 64
type Trie struct {
Index0 []uint16 // index for first byte (0xC0-0xFF)
Values0 []uint32 // index for first byte (0x00-0x7F)
Index []uint16
Values []uint32
}
const (
t1 = 0x00 // 0000 0000
tx = 0x80 // 1000 0000
t2 = 0xC0 // 1100 0000
t3 = 0xE0 // 1110 0000
t4 = 0xF0 // 1111 0000
t5 = 0xF8 // 1111 1000
t6 = 0xFC // 1111 1100
te = 0xFE // 1111 1110
)
func (t *Trie) lookupValue(n uint16, b byte) Elem {
return Elem(t.Values[int(n)<<6+int(b)])
}
// lookup returns the trie value for the first UTF-8 encoding in s and
// the width in bytes of this encoding. The size will be 0 if s does not
// hold enough bytes to complete the encoding. len(s) must be greater than 0.
func (t *Trie) lookup(s []byte) (v Elem, sz int) {
c0 := s[0]
switch {
case c0 < tx:
return Elem(t.Values0[c0]), 1
case c0 < t2:
return 0, 1
case c0 < t3:
if len(s) < 2 {
return 0, 0
}
i := t.Index0[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
return t.lookupValue(i, c1), 2
case c0 < t4:
if len(s) < 3 {
return 0, 0
}
i := t.Index0[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
o := int(i)<<6 + int(c1)
i = t.Index[o]
c2 := s[2]
if c2 < tx || t2 <= c2 {
return 0, 2
}
return t.lookupValue(i, c2), 3
case c0 < t5:
if len(s) < 4 {
return 0, 0
}
i := t.Index0[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
o := int(i)<<6 + int(c1)
i = t.Index[o]
c2 := s[2]
if c2 < tx || t2 <= c2 {
return 0, 2
}
o = int(i)<<6 + int(c2)
i = t.Index[o]
c3 := s[3]
if c3 < tx || t2 <= c3 {
return 0, 3
}
return t.lookupValue(i, c3), 4
}
// Illegal rune
return 0, 1
}
// The body of lookupString is a verbatim copy of that of lookup.
func (t *Trie) lookupString(s string) (v Elem, sz int) {
c0 := s[0]
switch {
case c0 < tx:
return Elem(t.Values0[c0]), 1
case c0 < t2:
return 0, 1
case c0 < t3:
if len(s) < 2 {
return 0, 0
}
i := t.Index0[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
return t.lookupValue(i, c1), 2
case c0 < t4:
if len(s) < 3 {
return 0, 0
}
i := t.Index0[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
o := int(i)<<6 + int(c1)
i = t.Index[o]
c2 := s[2]
if c2 < tx || t2 <= c2 {
return 0, 2
}
return t.lookupValue(i, c2), 3
case c0 < t5:
if len(s) < 4 {
return 0, 0
}
i := t.Index0[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
o := int(i)<<6 + int(c1)
i = t.Index[o]
c2 := s[2]
if c2 < tx || t2 <= c2 {
return 0, 2
}
o = int(i)<<6 + int(c2)
i = t.Index[o]
c3 := s[3]
if c3 < tx || t2 <= c3 {
return 0, 3
}
return t.lookupValue(i, c3), 4
}
// Illegal rune
return 0, 1
}
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