William Kurkian | 6ea97f8 | 2019-03-13 15:51:55 -0400 | [diff] [blame^] | 1 | // Copyright 2014 The Go Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style |
| 3 | // license that can be found in the LICENSE file. |
| 4 | |
| 5 | package triegen |
| 6 | |
| 7 | import ( |
| 8 | "bytes" |
| 9 | "fmt" |
| 10 | "io" |
| 11 | "strings" |
| 12 | "text/template" |
| 13 | ) |
| 14 | |
| 15 | // print writes all the data structures as well as the code necessary to use the |
| 16 | // trie to w. |
| 17 | func (b *builder) print(w io.Writer) error { |
| 18 | b.Stats.NValueEntries = len(b.ValueBlocks) * blockSize |
| 19 | b.Stats.NValueBytes = len(b.ValueBlocks) * blockSize * b.ValueSize |
| 20 | b.Stats.NIndexEntries = len(b.IndexBlocks) * blockSize |
| 21 | b.Stats.NIndexBytes = len(b.IndexBlocks) * blockSize * b.IndexSize |
| 22 | b.Stats.NHandleBytes = len(b.Trie) * 2 * b.IndexSize |
| 23 | |
| 24 | // If we only have one root trie, all starter blocks are at position 0 and |
| 25 | // we can access the arrays directly. |
| 26 | if len(b.Trie) == 1 { |
| 27 | // At this point we cannot refer to the generated tables directly. |
| 28 | b.ASCIIBlock = b.Name + "Values" |
| 29 | b.StarterBlock = b.Name + "Index" |
| 30 | } else { |
| 31 | // Otherwise we need to have explicit starter indexes in the trie |
| 32 | // structure. |
| 33 | b.ASCIIBlock = "t.ascii" |
| 34 | b.StarterBlock = "t.utf8Start" |
| 35 | } |
| 36 | |
| 37 | b.SourceType = "[]byte" |
| 38 | if err := lookupGen.Execute(w, b); err != nil { |
| 39 | return err |
| 40 | } |
| 41 | |
| 42 | b.SourceType = "string" |
| 43 | if err := lookupGen.Execute(w, b); err != nil { |
| 44 | return err |
| 45 | } |
| 46 | |
| 47 | if err := trieGen.Execute(w, b); err != nil { |
| 48 | return err |
| 49 | } |
| 50 | |
| 51 | for _, c := range b.Compactions { |
| 52 | if err := c.c.Print(w); err != nil { |
| 53 | return err |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | return nil |
| 58 | } |
| 59 | |
| 60 | func printValues(n int, values []uint64) string { |
| 61 | w := &bytes.Buffer{} |
| 62 | boff := n * blockSize |
| 63 | fmt.Fprintf(w, "\t// Block %#x, offset %#x", n, boff) |
| 64 | var newline bool |
| 65 | for i, v := range values { |
| 66 | if i%6 == 0 { |
| 67 | newline = true |
| 68 | } |
| 69 | if v != 0 { |
| 70 | if newline { |
| 71 | fmt.Fprintf(w, "\n") |
| 72 | newline = false |
| 73 | } |
| 74 | fmt.Fprintf(w, "\t%#02x:%#04x, ", boff+i, v) |
| 75 | } |
| 76 | } |
| 77 | return w.String() |
| 78 | } |
| 79 | |
| 80 | func printIndex(b *builder, nr int, n *node) string { |
| 81 | w := &bytes.Buffer{} |
| 82 | boff := nr * blockSize |
| 83 | fmt.Fprintf(w, "\t// Block %#x, offset %#x", nr, boff) |
| 84 | var newline bool |
| 85 | for i, c := range n.children { |
| 86 | if i%8 == 0 { |
| 87 | newline = true |
| 88 | } |
| 89 | if c != nil { |
| 90 | v := b.Compactions[c.index.compaction].Offset + uint32(c.index.index) |
| 91 | if v != 0 { |
| 92 | if newline { |
| 93 | fmt.Fprintf(w, "\n") |
| 94 | newline = false |
| 95 | } |
| 96 | fmt.Fprintf(w, "\t%#02x:%#02x, ", boff+i, v) |
| 97 | } |
| 98 | } |
| 99 | } |
| 100 | return w.String() |
| 101 | } |
| 102 | |
| 103 | var ( |
| 104 | trieGen = template.Must(template.New("trie").Funcs(template.FuncMap{ |
| 105 | "printValues": printValues, |
| 106 | "printIndex": printIndex, |
| 107 | "title": strings.Title, |
| 108 | "dec": func(x int) int { return x - 1 }, |
| 109 | "psize": func(n int) string { |
| 110 | return fmt.Sprintf("%d bytes (%.2f KiB)", n, float64(n)/1024) |
| 111 | }, |
| 112 | }).Parse(trieTemplate)) |
| 113 | lookupGen = template.Must(template.New("lookup").Parse(lookupTemplate)) |
| 114 | ) |
| 115 | |
| 116 | // TODO: consider the return type of lookup. It could be uint64, even if the |
| 117 | // internal value type is smaller. We will have to verify this with the |
| 118 | // performance of unicode/norm, which is very sensitive to such changes. |
| 119 | const trieTemplate = `{{$b := .}}{{$multi := gt (len .Trie) 1}} |
| 120 | // {{.Name}}Trie. Total size: {{psize .Size}}. Checksum: {{printf "%08x" .Checksum}}. |
| 121 | type {{.Name}}Trie struct { {{if $multi}} |
| 122 | ascii []{{.ValueType}} // index for ASCII bytes |
| 123 | utf8Start []{{.IndexType}} // index for UTF-8 bytes >= 0xC0 |
| 124 | {{end}}} |
| 125 | |
| 126 | func new{{title .Name}}Trie(i int) *{{.Name}}Trie { {{if $multi}} |
| 127 | h := {{.Name}}TrieHandles[i] |
| 128 | return &{{.Name}}Trie{ {{.Name}}Values[uint32(h.ascii)<<6:], {{.Name}}Index[uint32(h.multi)<<6:] } |
| 129 | } |
| 130 | |
| 131 | type {{.Name}}TrieHandle struct { |
| 132 | ascii, multi {{.IndexType}} |
| 133 | } |
| 134 | |
| 135 | // {{.Name}}TrieHandles: {{len .Trie}} handles, {{.Stats.NHandleBytes}} bytes |
| 136 | var {{.Name}}TrieHandles = [{{len .Trie}}]{{.Name}}TrieHandle{ |
| 137 | {{range .Trie}} { {{.ASCIIIndex}}, {{.StarterIndex}} }, // {{printf "%08x" .Checksum}}: {{.Name}} |
| 138 | {{end}}}{{else}} |
| 139 | return &{{.Name}}Trie{} |
| 140 | } |
| 141 | {{end}} |
| 142 | // lookupValue determines the type of block n and looks up the value for b. |
| 143 | func (t *{{.Name}}Trie) lookupValue(n uint32, b byte) {{.ValueType}}{{$last := dec (len .Compactions)}} { |
| 144 | switch { {{range $i, $c := .Compactions}} |
| 145 | {{if eq $i $last}}default{{else}}case n < {{$c.Cutoff}}{{end}}:{{if ne $i 0}} |
| 146 | n -= {{$c.Offset}}{{end}} |
| 147 | return {{print $b.ValueType}}({{$c.Handler}}){{end}} |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | // {{.Name}}Values: {{len .ValueBlocks}} blocks, {{.Stats.NValueEntries}} entries, {{.Stats.NValueBytes}} bytes |
| 152 | // The third block is the zero block. |
| 153 | var {{.Name}}Values = [{{.Stats.NValueEntries}}]{{.ValueType}} { |
| 154 | {{range $i, $v := .ValueBlocks}}{{printValues $i $v}} |
| 155 | {{end}}} |
| 156 | |
| 157 | // {{.Name}}Index: {{len .IndexBlocks}} blocks, {{.Stats.NIndexEntries}} entries, {{.Stats.NIndexBytes}} bytes |
| 158 | // Block 0 is the zero block. |
| 159 | var {{.Name}}Index = [{{.Stats.NIndexEntries}}]{{.IndexType}} { |
| 160 | {{range $i, $v := .IndexBlocks}}{{printIndex $b $i $v}} |
| 161 | {{end}}} |
| 162 | ` |
| 163 | |
| 164 | // TODO: consider allowing zero-length strings after evaluating performance with |
| 165 | // unicode/norm. |
| 166 | const lookupTemplate = ` |
| 167 | // lookup{{if eq .SourceType "string"}}String{{end}} returns the trie value for the first UTF-8 encoding in s and |
| 168 | // the width in bytes of this encoding. The size will be 0 if s does not |
| 169 | // hold enough bytes to complete the encoding. len(s) must be greater than 0. |
| 170 | func (t *{{.Name}}Trie) lookup{{if eq .SourceType "string"}}String{{end}}(s {{.SourceType}}) (v {{.ValueType}}, sz int) { |
| 171 | c0 := s[0] |
| 172 | switch { |
| 173 | case c0 < 0x80: // is ASCII |
| 174 | return {{.ASCIIBlock}}[c0], 1 |
| 175 | case c0 < 0xC2: |
| 176 | return 0, 1 // Illegal UTF-8: not a starter, not ASCII. |
| 177 | case c0 < 0xE0: // 2-byte UTF-8 |
| 178 | if len(s) < 2 { |
| 179 | return 0, 0 |
| 180 | } |
| 181 | i := {{.StarterBlock}}[c0] |
| 182 | c1 := s[1] |
| 183 | if c1 < 0x80 || 0xC0 <= c1 { |
| 184 | return 0, 1 // Illegal UTF-8: not a continuation byte. |
| 185 | } |
| 186 | return t.lookupValue(uint32(i), c1), 2 |
| 187 | case c0 < 0xF0: // 3-byte UTF-8 |
| 188 | if len(s) < 3 { |
| 189 | return 0, 0 |
| 190 | } |
| 191 | i := {{.StarterBlock}}[c0] |
| 192 | c1 := s[1] |
| 193 | if c1 < 0x80 || 0xC0 <= c1 { |
| 194 | return 0, 1 // Illegal UTF-8: not a continuation byte. |
| 195 | } |
| 196 | o := uint32(i)<<6 + uint32(c1) |
| 197 | i = {{.Name}}Index[o] |
| 198 | c2 := s[2] |
| 199 | if c2 < 0x80 || 0xC0 <= c2 { |
| 200 | return 0, 2 // Illegal UTF-8: not a continuation byte. |
| 201 | } |
| 202 | return t.lookupValue(uint32(i), c2), 3 |
| 203 | case c0 < 0xF8: // 4-byte UTF-8 |
| 204 | if len(s) < 4 { |
| 205 | return 0, 0 |
| 206 | } |
| 207 | i := {{.StarterBlock}}[c0] |
| 208 | c1 := s[1] |
| 209 | if c1 < 0x80 || 0xC0 <= c1 { |
| 210 | return 0, 1 // Illegal UTF-8: not a continuation byte. |
| 211 | } |
| 212 | o := uint32(i)<<6 + uint32(c1) |
| 213 | i = {{.Name}}Index[o] |
| 214 | c2 := s[2] |
| 215 | if c2 < 0x80 || 0xC0 <= c2 { |
| 216 | return 0, 2 // Illegal UTF-8: not a continuation byte. |
| 217 | } |
| 218 | o = uint32(i)<<6 + uint32(c2) |
| 219 | i = {{.Name}}Index[o] |
| 220 | c3 := s[3] |
| 221 | if c3 < 0x80 || 0xC0 <= c3 { |
| 222 | return 0, 3 // Illegal UTF-8: not a continuation byte. |
| 223 | } |
| 224 | return t.lookupValue(uint32(i), c3), 4 |
| 225 | } |
| 226 | // Illegal rune |
| 227 | return 0, 1 |
| 228 | } |
| 229 | |
| 230 | // lookup{{if eq .SourceType "string"}}String{{end}}Unsafe returns the trie value for the first UTF-8 encoding in s. |
| 231 | // s must start with a full and valid UTF-8 encoded rune. |
| 232 | func (t *{{.Name}}Trie) lookup{{if eq .SourceType "string"}}String{{end}}Unsafe(s {{.SourceType}}) {{.ValueType}} { |
| 233 | c0 := s[0] |
| 234 | if c0 < 0x80 { // is ASCII |
| 235 | return {{.ASCIIBlock}}[c0] |
| 236 | } |
| 237 | i := {{.StarterBlock}}[c0] |
| 238 | if c0 < 0xE0 { // 2-byte UTF-8 |
| 239 | return t.lookupValue(uint32(i), s[1]) |
| 240 | } |
| 241 | i = {{.Name}}Index[uint32(i)<<6+uint32(s[1])] |
| 242 | if c0 < 0xF0 { // 3-byte UTF-8 |
| 243 | return t.lookupValue(uint32(i), s[2]) |
| 244 | } |
| 245 | i = {{.Name}}Index[uint32(i)<<6+uint32(s[2])] |
| 246 | if c0 < 0xF8 { // 4-byte UTF-8 |
| 247 | return t.lookupValue(uint32(i), s[3]) |
| 248 | } |
| 249 | return 0 |
| 250 | } |
| 251 | ` |