Serge Bazanski | cc25bdf | 2018-10-25 14:02:58 +0200 | [diff] [blame] | 1 | // Copyright 2015 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 gen |
| 6 | |
| 7 | import ( |
| 8 | "bytes" |
| 9 | "encoding/gob" |
| 10 | "fmt" |
| 11 | "hash" |
| 12 | "hash/fnv" |
| 13 | "io" |
| 14 | "log" |
| 15 | "os" |
| 16 | "reflect" |
| 17 | "strings" |
| 18 | "unicode" |
| 19 | "unicode/utf8" |
| 20 | ) |
| 21 | |
| 22 | // This file contains utilities for generating code. |
| 23 | |
| 24 | // TODO: other write methods like: |
| 25 | // - slices, maps, types, etc. |
| 26 | |
| 27 | // CodeWriter is a utility for writing structured code. It computes the content |
| 28 | // hash and size of written content. It ensures there are newlines between |
| 29 | // written code blocks. |
| 30 | type CodeWriter struct { |
| 31 | buf bytes.Buffer |
| 32 | Size int |
| 33 | Hash hash.Hash32 // content hash |
| 34 | gob *gob.Encoder |
| 35 | // For comments we skip the usual one-line separator if they are followed by |
| 36 | // a code block. |
| 37 | skipSep bool |
| 38 | } |
| 39 | |
| 40 | func (w *CodeWriter) Write(p []byte) (n int, err error) { |
| 41 | return w.buf.Write(p) |
| 42 | } |
| 43 | |
| 44 | // NewCodeWriter returns a new CodeWriter. |
| 45 | func NewCodeWriter() *CodeWriter { |
| 46 | h := fnv.New32() |
| 47 | return &CodeWriter{Hash: h, gob: gob.NewEncoder(h)} |
| 48 | } |
| 49 | |
| 50 | // WriteGoFile appends the buffer with the total size of all created structures |
| 51 | // and writes it as a Go file to the the given file with the given package name. |
| 52 | func (w *CodeWriter) WriteGoFile(filename, pkg string) { |
| 53 | f, err := os.Create(filename) |
| 54 | if err != nil { |
| 55 | log.Fatalf("Could not create file %s: %v", filename, err) |
| 56 | } |
| 57 | defer f.Close() |
| 58 | if _, err = w.WriteGo(f, pkg, ""); err != nil { |
| 59 | log.Fatalf("Error writing file %s: %v", filename, err) |
| 60 | } |
| 61 | } |
| 62 | |
| 63 | // WriteVersionedGoFile appends the buffer with the total size of all created |
| 64 | // structures and writes it as a Go file to the the given file with the given |
| 65 | // package name and build tags for the current Unicode version, |
| 66 | func (w *CodeWriter) WriteVersionedGoFile(filename, pkg string) { |
| 67 | tags := buildTags() |
| 68 | if tags != "" { |
| 69 | filename = insertVersion(filename, UnicodeVersion()) |
| 70 | } |
| 71 | f, err := os.Create(filename) |
| 72 | if err != nil { |
| 73 | log.Fatalf("Could not create file %s: %v", filename, err) |
| 74 | } |
| 75 | defer f.Close() |
| 76 | if _, err = w.WriteGo(f, pkg, tags); err != nil { |
| 77 | log.Fatalf("Error writing file %s: %v", filename, err) |
| 78 | } |
| 79 | } |
| 80 | |
| 81 | // WriteGo appends the buffer with the total size of all created structures and |
| 82 | // writes it as a Go file to the the given writer with the given package name. |
| 83 | func (w *CodeWriter) WriteGo(out io.Writer, pkg, tags string) (n int, err error) { |
| 84 | sz := w.Size |
| 85 | w.WriteComment("Total table size %d bytes (%dKiB); checksum: %X\n", sz, sz/1024, w.Hash.Sum32()) |
| 86 | defer w.buf.Reset() |
| 87 | return WriteGo(out, pkg, tags, w.buf.Bytes()) |
| 88 | } |
| 89 | |
| 90 | func (w *CodeWriter) printf(f string, x ...interface{}) { |
| 91 | fmt.Fprintf(w, f, x...) |
| 92 | } |
| 93 | |
| 94 | func (w *CodeWriter) insertSep() { |
| 95 | if w.skipSep { |
| 96 | w.skipSep = false |
| 97 | return |
| 98 | } |
| 99 | // Use at least two newlines to ensure a blank space between the previous |
| 100 | // block. WriteGoFile will remove extraneous newlines. |
| 101 | w.printf("\n\n") |
| 102 | } |
| 103 | |
| 104 | // WriteComment writes a comment block. All line starts are prefixed with "//". |
| 105 | // Initial empty lines are gobbled. The indentation for the first line is |
| 106 | // stripped from consecutive lines. |
| 107 | func (w *CodeWriter) WriteComment(comment string, args ...interface{}) { |
| 108 | s := fmt.Sprintf(comment, args...) |
| 109 | s = strings.Trim(s, "\n") |
| 110 | |
| 111 | // Use at least two newlines to ensure a blank space between the previous |
| 112 | // block. WriteGoFile will remove extraneous newlines. |
| 113 | w.printf("\n\n// ") |
| 114 | w.skipSep = true |
| 115 | |
| 116 | // strip first indent level. |
| 117 | sep := "\n" |
| 118 | for ; len(s) > 0 && (s[0] == '\t' || s[0] == ' '); s = s[1:] { |
| 119 | sep += s[:1] |
| 120 | } |
| 121 | |
| 122 | strings.NewReplacer(sep, "\n// ", "\n", "\n// ").WriteString(w, s) |
| 123 | |
| 124 | w.printf("\n") |
| 125 | } |
| 126 | |
| 127 | func (w *CodeWriter) writeSizeInfo(size int) { |
| 128 | w.printf("// Size: %d bytes\n", size) |
| 129 | } |
| 130 | |
| 131 | // WriteConst writes a constant of the given name and value. |
| 132 | func (w *CodeWriter) WriteConst(name string, x interface{}) { |
| 133 | w.insertSep() |
| 134 | v := reflect.ValueOf(x) |
| 135 | |
| 136 | switch v.Type().Kind() { |
| 137 | case reflect.String: |
| 138 | w.printf("const %s %s = ", name, typeName(x)) |
| 139 | w.WriteString(v.String()) |
| 140 | w.printf("\n") |
| 141 | default: |
| 142 | w.printf("const %s = %#v\n", name, x) |
| 143 | } |
| 144 | } |
| 145 | |
| 146 | // WriteVar writes a variable of the given name and value. |
| 147 | func (w *CodeWriter) WriteVar(name string, x interface{}) { |
| 148 | w.insertSep() |
| 149 | v := reflect.ValueOf(x) |
| 150 | oldSize := w.Size |
| 151 | sz := int(v.Type().Size()) |
| 152 | w.Size += sz |
| 153 | |
| 154 | switch v.Type().Kind() { |
| 155 | case reflect.String: |
| 156 | w.printf("var %s %s = ", name, typeName(x)) |
| 157 | w.WriteString(v.String()) |
| 158 | case reflect.Struct: |
| 159 | w.gob.Encode(x) |
| 160 | fallthrough |
| 161 | case reflect.Slice, reflect.Array: |
| 162 | w.printf("var %s = ", name) |
| 163 | w.writeValue(v) |
| 164 | w.writeSizeInfo(w.Size - oldSize) |
| 165 | default: |
| 166 | w.printf("var %s %s = ", name, typeName(x)) |
| 167 | w.gob.Encode(x) |
| 168 | w.writeValue(v) |
| 169 | w.writeSizeInfo(w.Size - oldSize) |
| 170 | } |
| 171 | w.printf("\n") |
| 172 | } |
| 173 | |
| 174 | func (w *CodeWriter) writeValue(v reflect.Value) { |
| 175 | x := v.Interface() |
| 176 | switch v.Kind() { |
| 177 | case reflect.String: |
| 178 | w.WriteString(v.String()) |
| 179 | case reflect.Array: |
| 180 | // Don't double count: callers of WriteArray count on the size being |
| 181 | // added, so we need to discount it here. |
| 182 | w.Size -= int(v.Type().Size()) |
| 183 | w.writeSlice(x, true) |
| 184 | case reflect.Slice: |
| 185 | w.writeSlice(x, false) |
| 186 | case reflect.Struct: |
| 187 | w.printf("%s{\n", typeName(v.Interface())) |
| 188 | t := v.Type() |
| 189 | for i := 0; i < v.NumField(); i++ { |
| 190 | w.printf("%s: ", t.Field(i).Name) |
| 191 | w.writeValue(v.Field(i)) |
| 192 | w.printf(",\n") |
| 193 | } |
| 194 | w.printf("}") |
| 195 | default: |
| 196 | w.printf("%#v", x) |
| 197 | } |
| 198 | } |
| 199 | |
| 200 | // WriteString writes a string literal. |
| 201 | func (w *CodeWriter) WriteString(s string) { |
| 202 | s = strings.Replace(s, `\`, `\\`, -1) |
| 203 | io.WriteString(w.Hash, s) // content hash |
| 204 | w.Size += len(s) |
| 205 | |
| 206 | const maxInline = 40 |
| 207 | if len(s) <= maxInline { |
| 208 | w.printf("%q", s) |
| 209 | return |
| 210 | } |
| 211 | |
| 212 | // We will render the string as a multi-line string. |
| 213 | const maxWidth = 80 - 4 - len(`"`) - len(`" +`) |
| 214 | |
| 215 | // When starting on its own line, go fmt indents line 2+ an extra level. |
| 216 | n, max := maxWidth, maxWidth-4 |
| 217 | |
| 218 | // As per https://golang.org/issue/18078, the compiler has trouble |
| 219 | // compiling the concatenation of many strings, s0 + s1 + s2 + ... + sN, |
| 220 | // for large N. We insert redundant, explicit parentheses to work around |
| 221 | // that, lowering the N at any given step: (s0 + s1 + ... + s63) + (s64 + |
| 222 | // ... + s127) + etc + (etc + ... + sN). |
| 223 | explicitParens, extraComment := len(s) > 128*1024, "" |
| 224 | if explicitParens { |
| 225 | w.printf(`(`) |
| 226 | extraComment = "; the redundant, explicit parens are for https://golang.org/issue/18078" |
| 227 | } |
| 228 | |
| 229 | // Print "" +\n, if a string does not start on its own line. |
| 230 | b := w.buf.Bytes() |
| 231 | if p := len(bytes.TrimRight(b, " \t")); p > 0 && b[p-1] != '\n' { |
| 232 | w.printf("\"\" + // Size: %d bytes%s\n", len(s), extraComment) |
| 233 | n, max = maxWidth, maxWidth |
| 234 | } |
| 235 | |
| 236 | w.printf(`"`) |
| 237 | |
| 238 | for sz, p, nLines := 0, 0, 0; p < len(s); { |
| 239 | var r rune |
| 240 | r, sz = utf8.DecodeRuneInString(s[p:]) |
| 241 | out := s[p : p+sz] |
| 242 | chars := 1 |
| 243 | if !unicode.IsPrint(r) || r == utf8.RuneError || r == '"' { |
| 244 | switch sz { |
| 245 | case 1: |
| 246 | out = fmt.Sprintf("\\x%02x", s[p]) |
| 247 | case 2, 3: |
| 248 | out = fmt.Sprintf("\\u%04x", r) |
| 249 | case 4: |
| 250 | out = fmt.Sprintf("\\U%08x", r) |
| 251 | } |
| 252 | chars = len(out) |
| 253 | } |
| 254 | if n -= chars; n < 0 { |
| 255 | nLines++ |
| 256 | if explicitParens && nLines&63 == 63 { |
| 257 | w.printf("\") + (\"") |
| 258 | } |
| 259 | w.printf("\" +\n\"") |
| 260 | n = max - len(out) |
| 261 | } |
| 262 | w.printf("%s", out) |
| 263 | p += sz |
| 264 | } |
| 265 | w.printf(`"`) |
| 266 | if explicitParens { |
| 267 | w.printf(`)`) |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | // WriteSlice writes a slice value. |
| 272 | func (w *CodeWriter) WriteSlice(x interface{}) { |
| 273 | w.writeSlice(x, false) |
| 274 | } |
| 275 | |
| 276 | // WriteArray writes an array value. |
| 277 | func (w *CodeWriter) WriteArray(x interface{}) { |
| 278 | w.writeSlice(x, true) |
| 279 | } |
| 280 | |
| 281 | func (w *CodeWriter) writeSlice(x interface{}, isArray bool) { |
| 282 | v := reflect.ValueOf(x) |
| 283 | w.gob.Encode(v.Len()) |
| 284 | w.Size += v.Len() * int(v.Type().Elem().Size()) |
| 285 | name := typeName(x) |
| 286 | if isArray { |
| 287 | name = fmt.Sprintf("[%d]%s", v.Len(), name[strings.Index(name, "]")+1:]) |
| 288 | } |
| 289 | if isArray { |
| 290 | w.printf("%s{\n", name) |
| 291 | } else { |
| 292 | w.printf("%s{ // %d elements\n", name, v.Len()) |
| 293 | } |
| 294 | |
| 295 | switch kind := v.Type().Elem().Kind(); kind { |
| 296 | case reflect.String: |
| 297 | for _, s := range x.([]string) { |
| 298 | w.WriteString(s) |
| 299 | w.printf(",\n") |
| 300 | } |
| 301 | case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, |
| 302 | reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64: |
| 303 | // nLine and nBlock are the number of elements per line and block. |
| 304 | nLine, nBlock, format := 8, 64, "%d," |
| 305 | switch kind { |
| 306 | case reflect.Uint8: |
| 307 | format = "%#02x," |
| 308 | case reflect.Uint16: |
| 309 | format = "%#04x," |
| 310 | case reflect.Uint32: |
| 311 | nLine, nBlock, format = 4, 32, "%#08x," |
| 312 | case reflect.Uint, reflect.Uint64: |
| 313 | nLine, nBlock, format = 4, 32, "%#016x," |
| 314 | case reflect.Int8: |
| 315 | nLine = 16 |
| 316 | } |
| 317 | n := nLine |
| 318 | for i := 0; i < v.Len(); i++ { |
| 319 | if i%nBlock == 0 && v.Len() > nBlock { |
| 320 | w.printf("// Entry %X - %X\n", i, i+nBlock-1) |
| 321 | } |
| 322 | x := v.Index(i).Interface() |
| 323 | w.gob.Encode(x) |
| 324 | w.printf(format, x) |
| 325 | if n--; n == 0 { |
| 326 | n = nLine |
| 327 | w.printf("\n") |
| 328 | } |
| 329 | } |
| 330 | w.printf("\n") |
| 331 | case reflect.Struct: |
| 332 | zero := reflect.Zero(v.Type().Elem()).Interface() |
| 333 | for i := 0; i < v.Len(); i++ { |
| 334 | x := v.Index(i).Interface() |
| 335 | w.gob.EncodeValue(v) |
| 336 | if !reflect.DeepEqual(zero, x) { |
| 337 | line := fmt.Sprintf("%#v,\n", x) |
| 338 | line = line[strings.IndexByte(line, '{'):] |
| 339 | w.printf("%d: ", i) |
| 340 | w.printf(line) |
| 341 | } |
| 342 | } |
| 343 | case reflect.Array: |
| 344 | for i := 0; i < v.Len(); i++ { |
| 345 | w.printf("%d: %#v,\n", i, v.Index(i).Interface()) |
| 346 | } |
| 347 | default: |
| 348 | panic("gen: slice elem type not supported") |
| 349 | } |
| 350 | w.printf("}") |
| 351 | } |
| 352 | |
| 353 | // WriteType writes a definition of the type of the given value and returns the |
| 354 | // type name. |
| 355 | func (w *CodeWriter) WriteType(x interface{}) string { |
| 356 | t := reflect.TypeOf(x) |
| 357 | w.printf("type %s struct {\n", t.Name()) |
| 358 | for i := 0; i < t.NumField(); i++ { |
| 359 | w.printf("\t%s %s\n", t.Field(i).Name, t.Field(i).Type) |
| 360 | } |
| 361 | w.printf("}\n") |
| 362 | return t.Name() |
| 363 | } |
| 364 | |
| 365 | // typeName returns the name of the go type of x. |
| 366 | func typeName(x interface{}) string { |
| 367 | t := reflect.ValueOf(x).Type() |
| 368 | return strings.Replace(fmt.Sprint(t), "main.", "", 1) |
| 369 | } |