Don Newton | 379ae25 | 2019-04-01 12:17:06 -0400 | [diff] [blame^] | 1 | // Copyright (C) MongoDB, Inc. 2017-present. |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); you may |
| 4 | // not use this file except in compliance with the License. You may obtain |
| 5 | // a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 |
| 6 | |
| 7 | package bsonrw |
| 8 | |
| 9 | import ( |
| 10 | "bytes" |
| 11 | "errors" |
| 12 | "fmt" |
| 13 | "io" |
| 14 | "math" |
| 15 | "strconv" |
| 16 | "strings" |
| 17 | "unicode" |
| 18 | ) |
| 19 | |
| 20 | type jsonTokenType byte |
| 21 | |
| 22 | const ( |
| 23 | jttBeginObject jsonTokenType = iota |
| 24 | jttEndObject |
| 25 | jttBeginArray |
| 26 | jttEndArray |
| 27 | jttColon |
| 28 | jttComma |
| 29 | jttInt32 |
| 30 | jttInt64 |
| 31 | jttDouble |
| 32 | jttString |
| 33 | jttBool |
| 34 | jttNull |
| 35 | jttEOF |
| 36 | ) |
| 37 | |
| 38 | type jsonToken struct { |
| 39 | t jsonTokenType |
| 40 | v interface{} |
| 41 | p int |
| 42 | } |
| 43 | |
| 44 | type jsonScanner struct { |
| 45 | r io.Reader |
| 46 | buf []byte |
| 47 | pos int |
| 48 | lastReadErr error |
| 49 | } |
| 50 | |
| 51 | // nextToken returns the next JSON token if one exists. A token is a character |
| 52 | // of the JSON grammar, a number, a string, or a literal. |
| 53 | func (js *jsonScanner) nextToken() (*jsonToken, error) { |
| 54 | c, err := js.readNextByte() |
| 55 | |
| 56 | // keep reading until a non-space is encountered (break on read error or EOF) |
| 57 | for isWhiteSpace(c) && err == nil { |
| 58 | c, err = js.readNextByte() |
| 59 | } |
| 60 | |
| 61 | if err == io.EOF { |
| 62 | return &jsonToken{t: jttEOF}, nil |
| 63 | } else if err != nil { |
| 64 | return nil, err |
| 65 | } |
| 66 | |
| 67 | // switch on the character |
| 68 | switch c { |
| 69 | case '{': |
| 70 | return &jsonToken{t: jttBeginObject, v: byte('{'), p: js.pos - 1}, nil |
| 71 | case '}': |
| 72 | return &jsonToken{t: jttEndObject, v: byte('}'), p: js.pos - 1}, nil |
| 73 | case '[': |
| 74 | return &jsonToken{t: jttBeginArray, v: byte('['), p: js.pos - 1}, nil |
| 75 | case ']': |
| 76 | return &jsonToken{t: jttEndArray, v: byte(']'), p: js.pos - 1}, nil |
| 77 | case ':': |
| 78 | return &jsonToken{t: jttColon, v: byte(':'), p: js.pos - 1}, nil |
| 79 | case ',': |
| 80 | return &jsonToken{t: jttComma, v: byte(','), p: js.pos - 1}, nil |
| 81 | case '"': // RFC-8259 only allows for double quotes (") not single (') |
| 82 | return js.scanString() |
| 83 | default: |
| 84 | // check if it's a number |
| 85 | if c == '-' || isDigit(c) { |
| 86 | return js.scanNumber(c) |
| 87 | } else if c == 't' || c == 'f' || c == 'n' { |
| 88 | // maybe a literal |
| 89 | return js.scanLiteral(c) |
| 90 | } else { |
| 91 | return nil, fmt.Errorf("invalid JSON input. Position: %d. Character: %c", js.pos-1, c) |
| 92 | } |
| 93 | } |
| 94 | } |
| 95 | |
| 96 | // readNextByte attempts to read the next byte from the buffer. If the buffer |
| 97 | // has been exhausted, this function calls readIntoBuf, thus refilling the |
| 98 | // buffer and resetting the read position to 0 |
| 99 | func (js *jsonScanner) readNextByte() (byte, error) { |
| 100 | if js.pos >= len(js.buf) { |
| 101 | err := js.readIntoBuf() |
| 102 | |
| 103 | if err != nil { |
| 104 | return 0, err |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | b := js.buf[js.pos] |
| 109 | js.pos++ |
| 110 | |
| 111 | return b, nil |
| 112 | } |
| 113 | |
| 114 | // readNNextBytes reads n bytes into dst, starting at offset |
| 115 | func (js *jsonScanner) readNNextBytes(dst []byte, n, offset int) error { |
| 116 | var err error |
| 117 | |
| 118 | for i := 0; i < n; i++ { |
| 119 | dst[i+offset], err = js.readNextByte() |
| 120 | if err != nil { |
| 121 | return err |
| 122 | } |
| 123 | } |
| 124 | |
| 125 | return nil |
| 126 | } |
| 127 | |
| 128 | // readIntoBuf reads up to 512 bytes from the scanner's io.Reader into the buffer |
| 129 | func (js *jsonScanner) readIntoBuf() error { |
| 130 | if js.lastReadErr != nil { |
| 131 | js.buf = js.buf[:0] |
| 132 | js.pos = 0 |
| 133 | return js.lastReadErr |
| 134 | } |
| 135 | |
| 136 | if cap(js.buf) == 0 { |
| 137 | js.buf = make([]byte, 0, 512) |
| 138 | } |
| 139 | |
| 140 | n, err := js.r.Read(js.buf[:cap(js.buf)]) |
| 141 | if err != nil { |
| 142 | js.lastReadErr = err |
| 143 | if n > 0 { |
| 144 | err = nil |
| 145 | } |
| 146 | } |
| 147 | js.buf = js.buf[:n] |
| 148 | js.pos = 0 |
| 149 | |
| 150 | return err |
| 151 | } |
| 152 | |
| 153 | func isWhiteSpace(c byte) bool { |
| 154 | return c == ' ' || c == '\t' || c == '\r' || c == '\n' |
| 155 | } |
| 156 | |
| 157 | func isDigit(c byte) bool { |
| 158 | return unicode.IsDigit(rune(c)) |
| 159 | } |
| 160 | |
| 161 | func isValueTerminator(c byte) bool { |
| 162 | return c == ',' || c == '}' || c == ']' || isWhiteSpace(c) |
| 163 | } |
| 164 | |
| 165 | // scanString reads from an opening '"' to a closing '"' and handles escaped characters |
| 166 | func (js *jsonScanner) scanString() (*jsonToken, error) { |
| 167 | var b bytes.Buffer |
| 168 | var c byte |
| 169 | var err error |
| 170 | |
| 171 | p := js.pos - 1 |
| 172 | |
| 173 | for { |
| 174 | c, err = js.readNextByte() |
| 175 | if err != nil { |
| 176 | if err == io.EOF { |
| 177 | return nil, errors.New("end of input in JSON string") |
| 178 | } |
| 179 | return nil, err |
| 180 | } |
| 181 | |
| 182 | switch c { |
| 183 | case '\\': |
| 184 | c, err = js.readNextByte() |
| 185 | switch c { |
| 186 | case '"', '\\', '/', '\'': |
| 187 | b.WriteByte(c) |
| 188 | case 'b': |
| 189 | b.WriteByte('\b') |
| 190 | case 'f': |
| 191 | b.WriteByte('\f') |
| 192 | case 'n': |
| 193 | b.WriteByte('\n') |
| 194 | case 'r': |
| 195 | b.WriteByte('\r') |
| 196 | case 't': |
| 197 | b.WriteByte('\t') |
| 198 | case 'u': |
| 199 | us := make([]byte, 4) |
| 200 | err = js.readNNextBytes(us, 4, 0) |
| 201 | if err != nil { |
| 202 | return nil, fmt.Errorf("invalid unicode sequence in JSON string: %s", us) |
| 203 | } |
| 204 | |
| 205 | s := fmt.Sprintf(`\u%s`, us) |
| 206 | s, err = strconv.Unquote(strings.Replace(strconv.Quote(s), `\\u`, `\u`, 1)) |
| 207 | if err != nil { |
| 208 | return nil, err |
| 209 | } |
| 210 | |
| 211 | b.WriteString(s) |
| 212 | default: |
| 213 | return nil, fmt.Errorf("invalid escape sequence in JSON string '\\%c'", c) |
| 214 | } |
| 215 | case '"': |
| 216 | return &jsonToken{t: jttString, v: b.String(), p: p}, nil |
| 217 | default: |
| 218 | b.WriteByte(c) |
| 219 | } |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | // scanLiteral reads an unquoted sequence of characters and determines if it is one of |
| 224 | // three valid JSON literals (true, false, null); if so, it returns the appropriate |
| 225 | // jsonToken; otherwise, it returns an error |
| 226 | func (js *jsonScanner) scanLiteral(first byte) (*jsonToken, error) { |
| 227 | p := js.pos - 1 |
| 228 | |
| 229 | lit := make([]byte, 4) |
| 230 | lit[0] = first |
| 231 | |
| 232 | err := js.readNNextBytes(lit, 3, 1) |
| 233 | if err != nil { |
| 234 | return nil, err |
| 235 | } |
| 236 | |
| 237 | c5, err := js.readNextByte() |
| 238 | |
| 239 | if bytes.Equal([]byte("true"), lit) && (isValueTerminator(c5) || err == io.EOF) { |
| 240 | js.pos = int(math.Max(0, float64(js.pos-1))) |
| 241 | return &jsonToken{t: jttBool, v: true, p: p}, nil |
| 242 | } else if bytes.Equal([]byte("null"), lit) && (isValueTerminator(c5) || err == io.EOF) { |
| 243 | js.pos = int(math.Max(0, float64(js.pos-1))) |
| 244 | return &jsonToken{t: jttNull, v: nil, p: p}, nil |
| 245 | } else if bytes.Equal([]byte("fals"), lit) { |
| 246 | if c5 == 'e' { |
| 247 | c5, err = js.readNextByte() |
| 248 | |
| 249 | if isValueTerminator(c5) || err == io.EOF { |
| 250 | js.pos = int(math.Max(0, float64(js.pos-1))) |
| 251 | return &jsonToken{t: jttBool, v: false, p: p}, nil |
| 252 | } |
| 253 | } |
| 254 | } |
| 255 | |
| 256 | return nil, fmt.Errorf("invalid JSON literal. Position: %d, literal: %s", p, lit) |
| 257 | } |
| 258 | |
| 259 | type numberScanState byte |
| 260 | |
| 261 | const ( |
| 262 | nssSawLeadingMinus numberScanState = iota |
| 263 | nssSawLeadingZero |
| 264 | nssSawIntegerDigits |
| 265 | nssSawDecimalPoint |
| 266 | nssSawFractionDigits |
| 267 | nssSawExponentLetter |
| 268 | nssSawExponentSign |
| 269 | nssSawExponentDigits |
| 270 | nssDone |
| 271 | nssInvalid |
| 272 | ) |
| 273 | |
| 274 | // scanNumber reads a JSON number (according to RFC-8259) |
| 275 | func (js *jsonScanner) scanNumber(first byte) (*jsonToken, error) { |
| 276 | var b bytes.Buffer |
| 277 | var s numberScanState |
| 278 | var c byte |
| 279 | var err error |
| 280 | |
| 281 | t := jttInt64 // assume it's an int64 until the type can be determined |
| 282 | start := js.pos - 1 |
| 283 | |
| 284 | b.WriteByte(first) |
| 285 | |
| 286 | switch first { |
| 287 | case '-': |
| 288 | s = nssSawLeadingMinus |
| 289 | case '0': |
| 290 | s = nssSawLeadingZero |
| 291 | default: |
| 292 | s = nssSawIntegerDigits |
| 293 | } |
| 294 | |
| 295 | for { |
| 296 | c, err = js.readNextByte() |
| 297 | |
| 298 | if err != nil && err != io.EOF { |
| 299 | return nil, err |
| 300 | } |
| 301 | |
| 302 | switch s { |
| 303 | case nssSawLeadingMinus: |
| 304 | switch c { |
| 305 | case '0': |
| 306 | s = nssSawLeadingZero |
| 307 | b.WriteByte(c) |
| 308 | default: |
| 309 | if isDigit(c) { |
| 310 | s = nssSawIntegerDigits |
| 311 | b.WriteByte(c) |
| 312 | } else { |
| 313 | s = nssInvalid |
| 314 | } |
| 315 | } |
| 316 | case nssSawLeadingZero: |
| 317 | switch c { |
| 318 | case '.': |
| 319 | s = nssSawDecimalPoint |
| 320 | b.WriteByte(c) |
| 321 | case 'e', 'E': |
| 322 | s = nssSawExponentLetter |
| 323 | b.WriteByte(c) |
| 324 | case '}', ']', ',': |
| 325 | s = nssDone |
| 326 | default: |
| 327 | if isWhiteSpace(c) || err == io.EOF { |
| 328 | s = nssDone |
| 329 | } else { |
| 330 | s = nssInvalid |
| 331 | } |
| 332 | } |
| 333 | case nssSawIntegerDigits: |
| 334 | switch c { |
| 335 | case '.': |
| 336 | s = nssSawDecimalPoint |
| 337 | b.WriteByte(c) |
| 338 | case 'e', 'E': |
| 339 | s = nssSawExponentLetter |
| 340 | b.WriteByte(c) |
| 341 | case '}', ']', ',': |
| 342 | s = nssDone |
| 343 | default: |
| 344 | if isWhiteSpace(c) || err == io.EOF { |
| 345 | s = nssDone |
| 346 | } else if isDigit(c) { |
| 347 | s = nssSawIntegerDigits |
| 348 | b.WriteByte(c) |
| 349 | } else { |
| 350 | s = nssInvalid |
| 351 | } |
| 352 | } |
| 353 | case nssSawDecimalPoint: |
| 354 | t = jttDouble |
| 355 | if isDigit(c) { |
| 356 | s = nssSawFractionDigits |
| 357 | b.WriteByte(c) |
| 358 | } else { |
| 359 | s = nssInvalid |
| 360 | } |
| 361 | case nssSawFractionDigits: |
| 362 | switch c { |
| 363 | case 'e', 'E': |
| 364 | s = nssSawExponentLetter |
| 365 | b.WriteByte(c) |
| 366 | case '}', ']', ',': |
| 367 | s = nssDone |
| 368 | default: |
| 369 | if isWhiteSpace(c) || err == io.EOF { |
| 370 | s = nssDone |
| 371 | } else if isDigit(c) { |
| 372 | s = nssSawFractionDigits |
| 373 | b.WriteByte(c) |
| 374 | } else { |
| 375 | s = nssInvalid |
| 376 | } |
| 377 | } |
| 378 | case nssSawExponentLetter: |
| 379 | t = jttDouble |
| 380 | switch c { |
| 381 | case '+', '-': |
| 382 | s = nssSawExponentSign |
| 383 | b.WriteByte(c) |
| 384 | default: |
| 385 | if isDigit(c) { |
| 386 | s = nssSawExponentDigits |
| 387 | b.WriteByte(c) |
| 388 | } else { |
| 389 | s = nssInvalid |
| 390 | } |
| 391 | } |
| 392 | case nssSawExponentSign: |
| 393 | if isDigit(c) { |
| 394 | s = nssSawExponentDigits |
| 395 | b.WriteByte(c) |
| 396 | } else { |
| 397 | s = nssInvalid |
| 398 | } |
| 399 | case nssSawExponentDigits: |
| 400 | switch c { |
| 401 | case '}', ']', ',': |
| 402 | s = nssDone |
| 403 | default: |
| 404 | if isWhiteSpace(c) || err == io.EOF { |
| 405 | s = nssDone |
| 406 | } else if isDigit(c) { |
| 407 | s = nssSawExponentDigits |
| 408 | b.WriteByte(c) |
| 409 | } else { |
| 410 | s = nssInvalid |
| 411 | } |
| 412 | } |
| 413 | } |
| 414 | |
| 415 | switch s { |
| 416 | case nssInvalid: |
| 417 | return nil, fmt.Errorf("invalid JSON number. Position: %d", start) |
| 418 | case nssDone: |
| 419 | js.pos = int(math.Max(0, float64(js.pos-1))) |
| 420 | if t != jttDouble { |
| 421 | v, err := strconv.ParseInt(b.String(), 10, 64) |
| 422 | if err == nil { |
| 423 | if v < math.MinInt32 || v > math.MaxInt32 { |
| 424 | return &jsonToken{t: jttInt64, v: v, p: start}, nil |
| 425 | } |
| 426 | |
| 427 | return &jsonToken{t: jttInt32, v: int32(v), p: start}, nil |
| 428 | } |
| 429 | } |
| 430 | |
| 431 | v, err := strconv.ParseFloat(b.String(), 64) |
| 432 | if err != nil { |
| 433 | return nil, err |
| 434 | } |
| 435 | |
| 436 | return &jsonToken{t: jttDouble, v: v, p: start}, nil |
| 437 | } |
| 438 | } |
| 439 | } |