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
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
// Copyright 2011 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.
// Trie table generator.
// Used by make*tables tools to generate a go file with trie data structures
// for mapping UTF-8 to a 16-bit value. 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 with 16-bit values.
package main
import (
"fmt"
"hash/crc32"
"log"
"utf8"
)
// Intermediate trie structure
type trieNode struct {
table [256]*trieNode
value uint16
b byte
leaf bool
}
func newNode() *trieNode {
return new(trieNode)
}
func (n trieNode) String() string {
s := fmt.Sprint("trieNode{table: { non-nil at index: ")
for i, v := range n.table {
if v != nil {
s += fmt.Sprintf("%d, ", i)
}
}
s += fmt.Sprintf("}, value:%#x, b:%#x leaf:%v}", n.value, n.b, n.leaf)
return s
}
func (n trieNode) isInternal() bool {
internal := true
for i := 0; i < 256; i++ {
if nn := n.table[i]; nn != nil {
if !internal && !nn.leaf {
log.Fatalf("triegen: isInternal: node contains both leaf and non-leaf children (%v)", n)
}
internal = internal && !nn.leaf
}
}
return internal
}
func (n *trieNode) insert(rune int, value uint16) {
var p [utf8.UTFMax]byte
sz := utf8.EncodeRune(p[:], rune)
for i := 0; i < sz; i++ {
if n.leaf {
log.Fatalf("triegen: insert: node (%#v) should not be a leaf", n)
}
nn := n.table[p[i]]
if nn == nil {
nn = newNode()
nn.b = p[i]
n.table[p[i]] = nn
}
n = nn
}
n.value = value
n.leaf = true
}
type nodeIndex struct {
lookupBlocks []*trieNode
valueBlocks []*trieNode
lookupBlockIdx map[uint32]uint16
valueBlockIdx map[uint32]uint16
}
func newIndex() *nodeIndex {
index := &nodeIndex{}
index.lookupBlocks = make([]*trieNode, 0)
index.valueBlocks = make([]*trieNode, 0)
index.lookupBlockIdx = make(map[uint32]uint16)
index.valueBlockIdx = make(map[uint32]uint16)
return index
}
func computeOffsets(index *nodeIndex, n *trieNode) uint16 {
if n.leaf {
return n.value
}
hasher := crc32.New(crc32.MakeTable(crc32.IEEE))
// We only index continuation bytes.
for i := 0; i < 64; i++ {
var v uint16 = 0
if nn := n.table[0x80+i]; nn != nil {
v = computeOffsets(index, nn)
}
hasher.Write([]byte{uint8(v >> 8), uint8(v)})
}
h := hasher.Sum32()
if n.isInternal() {
v, ok := index.lookupBlockIdx[h]
if !ok {
v = uint16(len(index.lookupBlocks))
index.lookupBlocks = append(index.lookupBlocks, n)
index.lookupBlockIdx[h] = v
}
n.value = v
} else {
v, ok := index.valueBlockIdx[h]
if !ok {
v = uint16(len(index.valueBlocks))
index.valueBlocks = append(index.valueBlocks, n)
index.valueBlockIdx[h] = v
}
n.value = v
}
return n.value
}
func printValueBlock(nr int, n *trieNode, offset int) {
boff := nr * 64
fmt.Printf("\n// Block %#x, offset %#x", nr, boff)
var printnewline bool
for i := 0; i < 64; i++ {
if i%6 == 0 {
printnewline = true
}
v := uint16(0)
if nn := n.table[i+offset]; nn != nil {
v = nn.value
}
if v != 0 {
if printnewline {
fmt.Printf("\n")
printnewline = false
}
fmt.Printf("%#04x:%#04x, ", nr*64+i, v)
}
}
}
func printLookupBlock(nr int, n *trieNode, offset int) {
boff := nr * 64
fmt.Printf("\n// Block %#x, offset %#x", nr, boff)
var printnewline bool
for i := 0; i < 64; i++ {
if i%8 == 0 {
printnewline = true
}
v := uint16(0)
if nn := n.table[i+offset]; nn != nil {
v = nn.value
}
if v != 0 {
if printnewline {
fmt.Printf("\n")
printnewline = false
}
fmt.Printf("%#03x:%#02x, ", boff+i, v)
}
}
}
// printTables returns the size in bytes of the generated tables.
func (t *trieNode) printTables(name string) int {
index := newIndex()
// Values for 7-bit ASCII are stored in first two block, followed by nil block.
index.valueBlocks = append(index.valueBlocks, nil, nil, nil)
// First byte of multi-byte UTF-8 codepoints are indexed in 4th block.
index.lookupBlocks = append(index.lookupBlocks, nil, nil, nil, nil)
// Index starter bytes of multi-byte UTF-8.
for i := 0xC0; i < 0x100; i++ {
if t.table[i] != nil {
computeOffsets(index, t.table[i])
}
}
nv := len(index.valueBlocks) * 64
fmt.Printf("// %sValues: %d entries, %d bytes\n", name, nv, nv*2)
fmt.Printf("// Block 2 is the null block.\n")
fmt.Printf("var %sValues = [%d]uint16 {", name, nv)
printValueBlock(0, t, 0)
printValueBlock(1, t, 64)
printValueBlock(2, newNode(), 0)
for i := 3; i < len(index.valueBlocks); i++ {
printValueBlock(i, index.valueBlocks[i], 0x80)
}
fmt.Print("\n}\n\n")
ni := len(index.lookupBlocks) * 64
fmt.Printf("// %sLookup: %d bytes\n", name, ni)
fmt.Printf("// Block 0 is the null block.\n")
fmt.Printf("var %sLookup = [%d]uint8 {", name, ni)
printLookupBlock(0, newNode(), 0)
printLookupBlock(1, newNode(), 0)
printLookupBlock(2, newNode(), 0)
printLookupBlock(3, t, 0xC0)
for i := 4; i < len(index.lookupBlocks); i++ {
printLookupBlock(i, index.lookupBlocks[i], 0x80)
}
fmt.Print("\n}\n\n")
fmt.Printf("var %sTrie = trie{ %sLookup[:], %sValues[:] }\n\n", name, name, name)
return nv*2 + ni
}
|
