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
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
|
// Copyright 2014 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 triegen
import (
"bytes"
"fmt"
"io"
"strings"
"text/template"
)
// print writes all the data structures as well as the code necessary to use the
// trie to w.
func (b *builder) print(w io.Writer) error {
b.Stats.NValueEntries = len(b.ValueBlocks) * blockSize
b.Stats.NValueBytes = len(b.ValueBlocks) * blockSize * b.ValueSize
b.Stats.NIndexEntries = len(b.IndexBlocks) * blockSize
b.Stats.NIndexBytes = len(b.IndexBlocks) * blockSize * b.IndexSize
b.Stats.NHandleBytes = len(b.Trie) * 2 * b.IndexSize
// If we only have one root trie, all starter blocks are at position 0 and
// we can access the arrays directly.
if len(b.Trie) == 1 {
// At this point we cannot refer to the generated tables directly.
b.ASCIIBlock = b.Name + "Values"
b.StarterBlock = b.Name + "Index"
} else {
// Otherwise we need to have explicit starter indexes in the trie
// structure.
b.ASCIIBlock = "t.ascii"
b.StarterBlock = "t.utf8Start"
}
b.SourceType = "[]byte"
if err := lookupGen.Execute(w, b); err != nil {
return err
}
b.SourceType = "string"
if err := lookupGen.Execute(w, b); err != nil {
return err
}
if err := trieGen.Execute(w, b); err != nil {
return err
}
for _, c := range b.Compactions {
if err := c.c.Print(w); err != nil {
return err
}
}
return nil
}
func printValues(n int, values []uint64) string {
w := &bytes.Buffer{}
boff := n * blockSize
fmt.Fprintf(w, "\t// Block %#x, offset %#x", n, boff)
var newline bool
for i, v := range values {
if i%6 == 0 {
newline = true
}
if v != 0 {
if newline {
fmt.Fprintf(w, "\n")
newline = false
}
fmt.Fprintf(w, "\t%#02x:%#04x, ", boff+i, v)
}
}
return w.String()
}
func printIndex(b *builder, nr int, n *node) string {
w := &bytes.Buffer{}
boff := nr * blockSize
fmt.Fprintf(w, "\t// Block %#x, offset %#x", nr, boff)
var newline bool
for i, c := range n.children {
if i%8 == 0 {
newline = true
}
if c != nil {
v := b.Compactions[c.index.compaction].Offset + uint32(c.index.index)
if v != 0 {
if newline {
fmt.Fprintf(w, "\n")
newline = false
}
fmt.Fprintf(w, "\t%#02x:%#02x, ", boff+i, v)
}
}
}
return w.String()
}
var (
trieGen = template.Must(template.New("trie").Funcs(template.FuncMap{
"printValues": printValues,
"printIndex": printIndex,
"title": strings.Title,
"dec": func(x int) int { return x - 1 },
"psize": func(n int) string {
return fmt.Sprintf("%d bytes (%.2f KiB)", n, float64(n)/1024)
},
}).Parse(trieTemplate))
lookupGen = template.Must(template.New("lookup").Parse(lookupTemplate))
)
// TODO: consider the return type of lookup. It could be uint64, even if the
// internal value type is smaller. We will have to verify this with the
// performance of unicode/norm, which is very sensitive to such changes.
const trieTemplate = `{{$b := .}}{{$multi := gt (len .Trie) 1}}
// {{.Name}}Trie. Total size: {{psize .Size}}. Checksum: {{printf "%08x" .Checksum}}.
type {{.Name}}Trie struct { {{if $multi}}
ascii []{{.ValueType}} // index for ASCII bytes
utf8Start []{{.IndexType}} // index for UTF-8 bytes >= 0xC0
{{end}}}
func new{{title .Name}}Trie(i int) *{{.Name}}Trie { {{if $multi}}
h := {{.Name}}TrieHandles[i]
return &{{.Name}}Trie{ {{.Name}}Values[uint32(h.ascii)<<6:], {{.Name}}Index[uint32(h.multi)<<6:] }
}
type {{.Name}}TrieHandle struct {
ascii, multi {{.IndexType}}
}
// {{.Name}}TrieHandles: {{len .Trie}} handles, {{.Stats.NHandleBytes}} bytes
var {{.Name}}TrieHandles = [{{len .Trie}}]{{.Name}}TrieHandle{
{{range .Trie}} { {{.ASCIIIndex}}, {{.StarterIndex}} }, // {{printf "%08x" .Checksum}}: {{.Name}}
{{end}}}{{else}}
return &{{.Name}}Trie{}
}
{{end}}
// lookupValue determines the type of block n and looks up the value for b.
func (t *{{.Name}}Trie) lookupValue(n uint32, b byte) {{.ValueType}}{{$last := dec (len .Compactions)}} {
switch { {{range $i, $c := .Compactions}}
{{if eq $i $last}}default{{else}}case n < {{$c.Cutoff}}{{end}}:{{if ne $i 0}}
n -= {{$c.Offset}}{{end}}
return {{print $b.ValueType}}({{$c.Handler}}){{end}}
}
}
// {{.Name}}Values: {{len .ValueBlocks}} blocks, {{.Stats.NValueEntries}} entries, {{.Stats.NValueBytes}} bytes
// The third block is the zero block.
var {{.Name}}Values = [{{.Stats.NValueEntries}}]{{.ValueType}} {
{{range $i, $v := .ValueBlocks}}{{printValues $i $v}}
{{end}}}
// {{.Name}}Index: {{len .IndexBlocks}} blocks, {{.Stats.NIndexEntries}} entries, {{.Stats.NIndexBytes}} bytes
// Block 0 is the zero block.
var {{.Name}}Index = [{{.Stats.NIndexEntries}}]{{.IndexType}} {
{{range $i, $v := .IndexBlocks}}{{printIndex $b $i $v}}
{{end}}}
`
// TODO: consider allowing zero-length strings after evaluating performance with
// unicode/norm.
const lookupTemplate = `
// lookup{{if eq .SourceType "string"}}String{{end}} 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 *{{.Name}}Trie) lookup{{if eq .SourceType "string"}}String{{end}}(s {{.SourceType}}) (v {{.ValueType}}, sz int) {
c0 := s[0]
switch {
case c0 < 0x80: // is ASCII
return {{.ASCIIBlock}}[c0], 1
case c0 < 0xC2:
return 0, 1 // Illegal UTF-8: not a starter, not ASCII.
case c0 < 0xE0: // 2-byte UTF-8
if len(s) < 2 {
return 0, 0
}
i := {{.StarterBlock}}[c0]
c1 := s[1]
if c1 < 0x80 || 0xC0 <= c1 {
return 0, 1 // Illegal UTF-8: not a continuation byte.
}
return t.lookupValue(uint32(i), c1), 2
case c0 < 0xF0: // 3-byte UTF-8
if len(s) < 3 {
return 0, 0
}
i := {{.StarterBlock}}[c0]
c1 := s[1]
if c1 < 0x80 || 0xC0 <= c1 {
return 0, 1 // Illegal UTF-8: not a continuation byte.
}
o := uint32(i)<<6 + uint32(c1)
i = {{.Name}}Index[o]
c2 := s[2]
if c2 < 0x80 || 0xC0 <= c2 {
return 0, 2 // Illegal UTF-8: not a continuation byte.
}
return t.lookupValue(uint32(i), c2), 3
case c0 < 0xF8: // 4-byte UTF-8
if len(s) < 4 {
return 0, 0
}
i := {{.StarterBlock}}[c0]
c1 := s[1]
if c1 < 0x80 || 0xC0 <= c1 {
return 0, 1 // Illegal UTF-8: not a continuation byte.
}
o := uint32(i)<<6 + uint32(c1)
i = {{.Name}}Index[o]
c2 := s[2]
if c2 < 0x80 || 0xC0 <= c2 {
return 0, 2 // Illegal UTF-8: not a continuation byte.
}
o = uint32(i)<<6 + uint32(c2)
i = {{.Name}}Index[o]
c3 := s[3]
if c3 < 0x80 || 0xC0 <= c3 {
return 0, 3 // Illegal UTF-8: not a continuation byte.
}
return t.lookupValue(uint32(i), c3), 4
}
// Illegal rune
return 0, 1
}
// lookup{{if eq .SourceType "string"}}String{{end}}Unsafe returns the trie value for the first UTF-8 encoding in s.
// s must start with a full and valid UTF-8 encoded rune.
func (t *{{.Name}}Trie) lookup{{if eq .SourceType "string"}}String{{end}}Unsafe(s {{.SourceType}}) {{.ValueType}} {
c0 := s[0]
if c0 < 0x80 { // is ASCII
return {{.ASCIIBlock}}[c0]
}
i := {{.StarterBlock}}[c0]
if c0 < 0xE0 { // 2-byte UTF-8
return t.lookupValue(uint32(i), s[1])
}
i = {{.Name}}Index[uint32(i)<<6+uint32(s[1])]
if c0 < 0xF0 { // 3-byte UTF-8
return t.lookupValue(uint32(i), s[2])
}
i = {{.Name}}Index[uint32(i)<<6+uint32(s[2])]
if c0 < 0xF8 { // 4-byte UTF-8
return t.lookupValue(uint32(i), s[3])
}
return 0
}
`
|
