1 // __ _____ _____ _____ 2 // __| | __| | | | JSON for Modern C++ 3 // | | |__ | | | | | | version 3.11.2 4 // |_____|_____|_____|_|___| https://github.com/nlohmann/json 5 // 6 // SPDX-FileCopyrightText: 2013-2022 Niels Lohmann <https://nlohmann.me> 7 // SPDX-License-Identifier: MIT 8 9 #pragma once 10 11 #include <array> // array 12 #include <clocale> // localeconv 13 #include <cstddef> // size_t 14 #include <cstdio> // snprintf 15 #include <cstdlib> // strtof, strtod, strtold, strtoll, strtoull 16 #include <initializer_list> // initializer_list 17 #include <string> // char_traits, string 18 #include <utility> // move 19 #include <vector> // vector 20 21 #include <nlohmann/detail/input/input_adapters.hpp> 22 #include <nlohmann/detail/input/position_t.hpp> 23 #include <nlohmann/detail/macro_scope.hpp> 24 25 NLOHMANN_JSON_NAMESPACE_BEGIN 26 namespace detail 27 { 28 29 /////////// 30 // lexer // 31 /////////// 32 33 template<typename BasicJsonType> 34 class lexer_base 35 { 36 public: 37 /// token types for the parser 38 enum class token_type 39 { 40 uninitialized, ///< indicating the scanner is uninitialized 41 literal_true, ///< the `true` literal 42 literal_false, ///< the `false` literal 43 literal_null, ///< the `null` literal 44 value_string, ///< a string -- use get_string() for actual value 45 value_unsigned, ///< an unsigned integer -- use get_number_unsigned() for actual value 46 value_integer, ///< a signed integer -- use get_number_integer() for actual value 47 value_float, ///< an floating point number -- use get_number_float() for actual value 48 begin_array, ///< the character for array begin `[` 49 begin_object, ///< the character for object begin `{` 50 end_array, ///< the character for array end `]` 51 end_object, ///< the character for object end `}` 52 name_separator, ///< the name separator `:` 53 value_separator, ///< the value separator `,` 54 parse_error, ///< indicating a parse error 55 end_of_input, ///< indicating the end of the input buffer 56 literal_or_value ///< a literal or the begin of a value (only for diagnostics) 57 }; 58 59 /// return name of values of type token_type (only used for errors) 60 JSON_HEDLEY_RETURNS_NON_NULL 61 JSON_HEDLEY_CONST token_type_name(const token_type t)62 static const char* token_type_name(const token_type t) noexcept 63 { 64 switch (t) 65 { 66 case token_type::uninitialized: 67 return "<uninitialized>"; 68 case token_type::literal_true: 69 return "true literal"; 70 case token_type::literal_false: 71 return "false literal"; 72 case token_type::literal_null: 73 return "null literal"; 74 case token_type::value_string: 75 return "string literal"; 76 case token_type::value_unsigned: 77 case token_type::value_integer: 78 case token_type::value_float: 79 return "number literal"; 80 case token_type::begin_array: 81 return "'['"; 82 case token_type::begin_object: 83 return "'{'"; 84 case token_type::end_array: 85 return "']'"; 86 case token_type::end_object: 87 return "'}'"; 88 case token_type::name_separator: 89 return "':'"; 90 case token_type::value_separator: 91 return "','"; 92 case token_type::parse_error: 93 return "<parse error>"; 94 case token_type::end_of_input: 95 return "end of input"; 96 case token_type::literal_or_value: 97 return "'[', '{', or a literal"; 98 // LCOV_EXCL_START 99 default: // catch non-enum values 100 return "unknown token"; 101 // LCOV_EXCL_STOP 102 } 103 } 104 }; 105 /*! 106 @brief lexical analysis 107 108 This class organizes the lexical analysis during JSON deserialization. 109 */ 110 template<typename BasicJsonType, typename InputAdapterType> 111 class lexer : public lexer_base<BasicJsonType> 112 { 113 using number_integer_t = typename BasicJsonType::number_integer_t; 114 using number_unsigned_t = typename BasicJsonType::number_unsigned_t; 115 using number_float_t = typename BasicJsonType::number_float_t; 116 using string_t = typename BasicJsonType::string_t; 117 using char_type = typename InputAdapterType::char_type; 118 using char_int_type = typename std::char_traits<char_type>::int_type; 119 120 public: 121 using token_type = typename lexer_base<BasicJsonType>::token_type; 122 lexer(InputAdapterType && adapter,bool ignore_comments_=false)123 explicit lexer(InputAdapterType&& adapter, bool ignore_comments_ = false) noexcept 124 : ia(std::move(adapter)) 125 , ignore_comments(ignore_comments_) 126 , decimal_point_char(static_cast<char_int_type>(get_decimal_point())) 127 {} 128 129 // delete because of pointer members 130 lexer(const lexer&) = delete; 131 lexer(lexer&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor) 132 lexer& operator=(lexer&) = delete; 133 lexer& operator=(lexer&&) = default; // NOLINT(hicpp-noexcept-move,performance-noexcept-move-constructor) 134 ~lexer() = default; 135 136 private: 137 ///////////////////// 138 // locales 139 ///////////////////// 140 141 /// return the locale-dependent decimal point 142 JSON_HEDLEY_PURE get_decimal_point()143 static char get_decimal_point() noexcept 144 { 145 const auto* loc = localeconv(); 146 JSON_ASSERT(loc != nullptr); 147 return (loc->decimal_point == nullptr) ? '.' : *(loc->decimal_point); 148 } 149 150 ///////////////////// 151 // scan functions 152 ///////////////////// 153 154 /*! 155 @brief get codepoint from 4 hex characters following `\u` 156 157 For input "\u c1 c2 c3 c4" the codepoint is: 158 (c1 * 0x1000) + (c2 * 0x0100) + (c3 * 0x0010) + c4 159 = (c1 << 12) + (c2 << 8) + (c3 << 4) + (c4 << 0) 160 161 Furthermore, the possible characters '0'..'9', 'A'..'F', and 'a'..'f' 162 must be converted to the integers 0x0..0x9, 0xA..0xF, 0xA..0xF, resp. The 163 conversion is done by subtracting the offset (0x30, 0x37, and 0x57) 164 between the ASCII value of the character and the desired integer value. 165 166 @return codepoint (0x0000..0xFFFF) or -1 in case of an error (e.g. EOF or 167 non-hex character) 168 */ get_codepoint()169 int get_codepoint() 170 { 171 // this function only makes sense after reading `\u` 172 JSON_ASSERT(current == 'u'); 173 int codepoint = 0; 174 175 const auto factors = { 12u, 8u, 4u, 0u }; 176 for (const auto factor : factors) 177 { 178 get(); 179 180 if (current >= '0' && current <= '9') 181 { 182 codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x30u) << factor); 183 } 184 else if (current >= 'A' && current <= 'F') 185 { 186 codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x37u) << factor); 187 } 188 else if (current >= 'a' && current <= 'f') 189 { 190 codepoint += static_cast<int>((static_cast<unsigned int>(current) - 0x57u) << factor); 191 } 192 else 193 { 194 return -1; 195 } 196 } 197 198 JSON_ASSERT(0x0000 <= codepoint && codepoint <= 0xFFFF); 199 return codepoint; 200 } 201 202 /*! 203 @brief check if the next byte(s) are inside a given range 204 205 Adds the current byte and, for each passed range, reads a new byte and 206 checks if it is inside the range. If a violation was detected, set up an 207 error message and return false. Otherwise, return true. 208 209 @param[in] ranges list of integers; interpreted as list of pairs of 210 inclusive lower and upper bound, respectively 211 212 @pre The passed list @a ranges must have 2, 4, or 6 elements; that is, 213 1, 2, or 3 pairs. This precondition is enforced by an assertion. 214 215 @return true if and only if no range violation was detected 216 */ next_byte_in_range(std::initializer_list<char_int_type> ranges)217 bool next_byte_in_range(std::initializer_list<char_int_type> ranges) 218 { 219 JSON_ASSERT(ranges.size() == 2 || ranges.size() == 4 || ranges.size() == 6); 220 add(current); 221 222 for (auto range = ranges.begin(); range != ranges.end(); ++range) 223 { 224 get(); 225 if (JSON_HEDLEY_LIKELY(*range <= current && current <= *(++range))) 226 { 227 add(current); 228 } 229 else 230 { 231 error_message = "invalid string: ill-formed UTF-8 byte"; 232 return false; 233 } 234 } 235 236 return true; 237 } 238 239 /*! 240 @brief scan a string literal 241 242 This function scans a string according to Sect. 7 of RFC 8259. While 243 scanning, bytes are escaped and copied into buffer token_buffer. Then the 244 function returns successfully, token_buffer is *not* null-terminated (as it 245 may contain \0 bytes), and token_buffer.size() is the number of bytes in the 246 string. 247 248 @return token_type::value_string if string could be successfully scanned, 249 token_type::parse_error otherwise 250 251 @note In case of errors, variable error_message contains a textual 252 description. 253 */ scan_string()254 token_type scan_string() 255 { 256 // reset token_buffer (ignore opening quote) 257 reset(); 258 259 // we entered the function by reading an open quote 260 JSON_ASSERT(current == '\"'); 261 262 while (true) 263 { 264 // get next character 265 switch (get()) 266 { 267 // end of file while parsing string 268 case std::char_traits<char_type>::eof(): 269 { 270 error_message = "invalid string: missing closing quote"; 271 return token_type::parse_error; 272 } 273 274 // closing quote 275 case '\"': 276 { 277 return token_type::value_string; 278 } 279 280 // escapes 281 case '\\': 282 { 283 switch (get()) 284 { 285 // quotation mark 286 case '\"': 287 add('\"'); 288 break; 289 // reverse solidus 290 case '\\': 291 add('\\'); 292 break; 293 // solidus 294 case '/': 295 add('/'); 296 break; 297 // backspace 298 case 'b': 299 add('\b'); 300 break; 301 // form feed 302 case 'f': 303 add('\f'); 304 break; 305 // line feed 306 case 'n': 307 add('\n'); 308 break; 309 // carriage return 310 case 'r': 311 add('\r'); 312 break; 313 // tab 314 case 't': 315 add('\t'); 316 break; 317 318 // unicode escapes 319 case 'u': 320 { 321 const int codepoint1 = get_codepoint(); 322 int codepoint = codepoint1; // start with codepoint1 323 324 if (JSON_HEDLEY_UNLIKELY(codepoint1 == -1)) 325 { 326 error_message = "invalid string: '\\u' must be followed by 4 hex digits"; 327 return token_type::parse_error; 328 } 329 330 // check if code point is a high surrogate 331 if (0xD800 <= codepoint1 && codepoint1 <= 0xDBFF) 332 { 333 // expect next \uxxxx entry 334 if (JSON_HEDLEY_LIKELY(get() == '\\' && get() == 'u')) 335 { 336 const int codepoint2 = get_codepoint(); 337 338 if (JSON_HEDLEY_UNLIKELY(codepoint2 == -1)) 339 { 340 error_message = "invalid string: '\\u' must be followed by 4 hex digits"; 341 return token_type::parse_error; 342 } 343 344 // check if codepoint2 is a low surrogate 345 if (JSON_HEDLEY_LIKELY(0xDC00 <= codepoint2 && codepoint2 <= 0xDFFF)) 346 { 347 // overwrite codepoint 348 codepoint = static_cast<int>( 349 // high surrogate occupies the most significant 22 bits 350 (static_cast<unsigned int>(codepoint1) << 10u) 351 // low surrogate occupies the least significant 15 bits 352 + static_cast<unsigned int>(codepoint2) 353 // there is still the 0xD800, 0xDC00 and 0x10000 noise 354 // in the result, so we have to subtract with: 355 // (0xD800 << 10) + DC00 - 0x10000 = 0x35FDC00 356 - 0x35FDC00u); 357 } 358 else 359 { 360 error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF"; 361 return token_type::parse_error; 362 } 363 } 364 else 365 { 366 error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF"; 367 return token_type::parse_error; 368 } 369 } 370 else 371 { 372 if (JSON_HEDLEY_UNLIKELY(0xDC00 <= codepoint1 && codepoint1 <= 0xDFFF)) 373 { 374 error_message = "invalid string: surrogate U+DC00..U+DFFF must follow U+D800..U+DBFF"; 375 return token_type::parse_error; 376 } 377 } 378 379 // result of the above calculation yields a proper codepoint 380 JSON_ASSERT(0x00 <= codepoint && codepoint <= 0x10FFFF); 381 382 // translate codepoint into bytes 383 if (codepoint < 0x80) 384 { 385 // 1-byte characters: 0xxxxxxx (ASCII) 386 add(static_cast<char_int_type>(codepoint)); 387 } 388 else if (codepoint <= 0x7FF) 389 { 390 // 2-byte characters: 110xxxxx 10xxxxxx 391 add(static_cast<char_int_type>(0xC0u | (static_cast<unsigned int>(codepoint) >> 6u))); 392 add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu))); 393 } 394 else if (codepoint <= 0xFFFF) 395 { 396 // 3-byte characters: 1110xxxx 10xxxxxx 10xxxxxx 397 add(static_cast<char_int_type>(0xE0u | (static_cast<unsigned int>(codepoint) >> 12u))); 398 add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu))); 399 add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu))); 400 } 401 else 402 { 403 // 4-byte characters: 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx 404 add(static_cast<char_int_type>(0xF0u | (static_cast<unsigned int>(codepoint) >> 18u))); 405 add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 12u) & 0x3Fu))); 406 add(static_cast<char_int_type>(0x80u | ((static_cast<unsigned int>(codepoint) >> 6u) & 0x3Fu))); 407 add(static_cast<char_int_type>(0x80u | (static_cast<unsigned int>(codepoint) & 0x3Fu))); 408 } 409 410 break; 411 } 412 413 // other characters after escape 414 default: 415 error_message = "invalid string: forbidden character after backslash"; 416 return token_type::parse_error; 417 } 418 419 break; 420 } 421 422 // invalid control characters 423 case 0x00: 424 { 425 error_message = "invalid string: control character U+0000 (NUL) must be escaped to \\u0000"; 426 return token_type::parse_error; 427 } 428 429 case 0x01: 430 { 431 error_message = "invalid string: control character U+0001 (SOH) must be escaped to \\u0001"; 432 return token_type::parse_error; 433 } 434 435 case 0x02: 436 { 437 error_message = "invalid string: control character U+0002 (STX) must be escaped to \\u0002"; 438 return token_type::parse_error; 439 } 440 441 case 0x03: 442 { 443 error_message = "invalid string: control character U+0003 (ETX) must be escaped to \\u0003"; 444 return token_type::parse_error; 445 } 446 447 case 0x04: 448 { 449 error_message = "invalid string: control character U+0004 (EOT) must be escaped to \\u0004"; 450 return token_type::parse_error; 451 } 452 453 case 0x05: 454 { 455 error_message = "invalid string: control character U+0005 (ENQ) must be escaped to \\u0005"; 456 return token_type::parse_error; 457 } 458 459 case 0x06: 460 { 461 error_message = "invalid string: control character U+0006 (ACK) must be escaped to \\u0006"; 462 return token_type::parse_error; 463 } 464 465 case 0x07: 466 { 467 error_message = "invalid string: control character U+0007 (BEL) must be escaped to \\u0007"; 468 return token_type::parse_error; 469 } 470 471 case 0x08: 472 { 473 error_message = "invalid string: control character U+0008 (BS) must be escaped to \\u0008 or \\b"; 474 return token_type::parse_error; 475 } 476 477 case 0x09: 478 { 479 error_message = "invalid string: control character U+0009 (HT) must be escaped to \\u0009 or \\t"; 480 return token_type::parse_error; 481 } 482 483 case 0x0A: 484 { 485 error_message = "invalid string: control character U+000A (LF) must be escaped to \\u000A or \\n"; 486 return token_type::parse_error; 487 } 488 489 case 0x0B: 490 { 491 error_message = "invalid string: control character U+000B (VT) must be escaped to \\u000B"; 492 return token_type::parse_error; 493 } 494 495 case 0x0C: 496 { 497 error_message = "invalid string: control character U+000C (FF) must be escaped to \\u000C or \\f"; 498 return token_type::parse_error; 499 } 500 501 case 0x0D: 502 { 503 error_message = "invalid string: control character U+000D (CR) must be escaped to \\u000D or \\r"; 504 return token_type::parse_error; 505 } 506 507 case 0x0E: 508 { 509 error_message = "invalid string: control character U+000E (SO) must be escaped to \\u000E"; 510 return token_type::parse_error; 511 } 512 513 case 0x0F: 514 { 515 error_message = "invalid string: control character U+000F (SI) must be escaped to \\u000F"; 516 return token_type::parse_error; 517 } 518 519 case 0x10: 520 { 521 error_message = "invalid string: control character U+0010 (DLE) must be escaped to \\u0010"; 522 return token_type::parse_error; 523 } 524 525 case 0x11: 526 { 527 error_message = "invalid string: control character U+0011 (DC1) must be escaped to \\u0011"; 528 return token_type::parse_error; 529 } 530 531 case 0x12: 532 { 533 error_message = "invalid string: control character U+0012 (DC2) must be escaped to \\u0012"; 534 return token_type::parse_error; 535 } 536 537 case 0x13: 538 { 539 error_message = "invalid string: control character U+0013 (DC3) must be escaped to \\u0013"; 540 return token_type::parse_error; 541 } 542 543 case 0x14: 544 { 545 error_message = "invalid string: control character U+0014 (DC4) must be escaped to \\u0014"; 546 return token_type::parse_error; 547 } 548 549 case 0x15: 550 { 551 error_message = "invalid string: control character U+0015 (NAK) must be escaped to \\u0015"; 552 return token_type::parse_error; 553 } 554 555 case 0x16: 556 { 557 error_message = "invalid string: control character U+0016 (SYN) must be escaped to \\u0016"; 558 return token_type::parse_error; 559 } 560 561 case 0x17: 562 { 563 error_message = "invalid string: control character U+0017 (ETB) must be escaped to \\u0017"; 564 return token_type::parse_error; 565 } 566 567 case 0x18: 568 { 569 error_message = "invalid string: control character U+0018 (CAN) must be escaped to \\u0018"; 570 return token_type::parse_error; 571 } 572 573 case 0x19: 574 { 575 error_message = "invalid string: control character U+0019 (EM) must be escaped to \\u0019"; 576 return token_type::parse_error; 577 } 578 579 case 0x1A: 580 { 581 error_message = "invalid string: control character U+001A (SUB) must be escaped to \\u001A"; 582 return token_type::parse_error; 583 } 584 585 case 0x1B: 586 { 587 error_message = "invalid string: control character U+001B (ESC) must be escaped to \\u001B"; 588 return token_type::parse_error; 589 } 590 591 case 0x1C: 592 { 593 error_message = "invalid string: control character U+001C (FS) must be escaped to \\u001C"; 594 return token_type::parse_error; 595 } 596 597 case 0x1D: 598 { 599 error_message = "invalid string: control character U+001D (GS) must be escaped to \\u001D"; 600 return token_type::parse_error; 601 } 602 603 case 0x1E: 604 { 605 error_message = "invalid string: control character U+001E (RS) must be escaped to \\u001E"; 606 return token_type::parse_error; 607 } 608 609 case 0x1F: 610 { 611 error_message = "invalid string: control character U+001F (US) must be escaped to \\u001F"; 612 return token_type::parse_error; 613 } 614 615 // U+0020..U+007F (except U+0022 (quote) and U+005C (backspace)) 616 case 0x20: 617 case 0x21: 618 case 0x23: 619 case 0x24: 620 case 0x25: 621 case 0x26: 622 case 0x27: 623 case 0x28: 624 case 0x29: 625 case 0x2A: 626 case 0x2B: 627 case 0x2C: 628 case 0x2D: 629 case 0x2E: 630 case 0x2F: 631 case 0x30: 632 case 0x31: 633 case 0x32: 634 case 0x33: 635 case 0x34: 636 case 0x35: 637 case 0x36: 638 case 0x37: 639 case 0x38: 640 case 0x39: 641 case 0x3A: 642 case 0x3B: 643 case 0x3C: 644 case 0x3D: 645 case 0x3E: 646 case 0x3F: 647 case 0x40: 648 case 0x41: 649 case 0x42: 650 case 0x43: 651 case 0x44: 652 case 0x45: 653 case 0x46: 654 case 0x47: 655 case 0x48: 656 case 0x49: 657 case 0x4A: 658 case 0x4B: 659 case 0x4C: 660 case 0x4D: 661 case 0x4E: 662 case 0x4F: 663 case 0x50: 664 case 0x51: 665 case 0x52: 666 case 0x53: 667 case 0x54: 668 case 0x55: 669 case 0x56: 670 case 0x57: 671 case 0x58: 672 case 0x59: 673 case 0x5A: 674 case 0x5B: 675 case 0x5D: 676 case 0x5E: 677 case 0x5F: 678 case 0x60: 679 case 0x61: 680 case 0x62: 681 case 0x63: 682 case 0x64: 683 case 0x65: 684 case 0x66: 685 case 0x67: 686 case 0x68: 687 case 0x69: 688 case 0x6A: 689 case 0x6B: 690 case 0x6C: 691 case 0x6D: 692 case 0x6E: 693 case 0x6F: 694 case 0x70: 695 case 0x71: 696 case 0x72: 697 case 0x73: 698 case 0x74: 699 case 0x75: 700 case 0x76: 701 case 0x77: 702 case 0x78: 703 case 0x79: 704 case 0x7A: 705 case 0x7B: 706 case 0x7C: 707 case 0x7D: 708 case 0x7E: 709 case 0x7F: 710 { 711 add(current); 712 break; 713 } 714 715 // U+0080..U+07FF: bytes C2..DF 80..BF 716 case 0xC2: 717 case 0xC3: 718 case 0xC4: 719 case 0xC5: 720 case 0xC6: 721 case 0xC7: 722 case 0xC8: 723 case 0xC9: 724 case 0xCA: 725 case 0xCB: 726 case 0xCC: 727 case 0xCD: 728 case 0xCE: 729 case 0xCF: 730 case 0xD0: 731 case 0xD1: 732 case 0xD2: 733 case 0xD3: 734 case 0xD4: 735 case 0xD5: 736 case 0xD6: 737 case 0xD7: 738 case 0xD8: 739 case 0xD9: 740 case 0xDA: 741 case 0xDB: 742 case 0xDC: 743 case 0xDD: 744 case 0xDE: 745 case 0xDF: 746 { 747 if (JSON_HEDLEY_UNLIKELY(!next_byte_in_range({0x80, 0xBF}))) 748 { 749 return token_type::parse_error; 750 } 751 break; 752 } 753 754 // U+0800..U+0FFF: bytes E0 A0..BF 80..BF 755 case 0xE0: 756 { 757 if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0xA0, 0xBF, 0x80, 0xBF})))) 758 { 759 return token_type::parse_error; 760 } 761 break; 762 } 763 764 // U+1000..U+CFFF: bytes E1..EC 80..BF 80..BF 765 // U+E000..U+FFFF: bytes EE..EF 80..BF 80..BF 766 case 0xE1: 767 case 0xE2: 768 case 0xE3: 769 case 0xE4: 770 case 0xE5: 771 case 0xE6: 772 case 0xE7: 773 case 0xE8: 774 case 0xE9: 775 case 0xEA: 776 case 0xEB: 777 case 0xEC: 778 case 0xEE: 779 case 0xEF: 780 { 781 if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0xBF, 0x80, 0xBF})))) 782 { 783 return token_type::parse_error; 784 } 785 break; 786 } 787 788 // U+D000..U+D7FF: bytes ED 80..9F 80..BF 789 case 0xED: 790 { 791 if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0x9F, 0x80, 0xBF})))) 792 { 793 return token_type::parse_error; 794 } 795 break; 796 } 797 798 // U+10000..U+3FFFF F0 90..BF 80..BF 80..BF 799 case 0xF0: 800 { 801 if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x90, 0xBF, 0x80, 0xBF, 0x80, 0xBF})))) 802 { 803 return token_type::parse_error; 804 } 805 break; 806 } 807 808 // U+40000..U+FFFFF F1..F3 80..BF 80..BF 80..BF 809 case 0xF1: 810 case 0xF2: 811 case 0xF3: 812 { 813 if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0xBF, 0x80, 0xBF, 0x80, 0xBF})))) 814 { 815 return token_type::parse_error; 816 } 817 break; 818 } 819 820 // U+100000..U+10FFFF F4 80..8F 80..BF 80..BF 821 case 0xF4: 822 { 823 if (JSON_HEDLEY_UNLIKELY(!(next_byte_in_range({0x80, 0x8F, 0x80, 0xBF, 0x80, 0xBF})))) 824 { 825 return token_type::parse_error; 826 } 827 break; 828 } 829 830 // remaining bytes (80..C1 and F5..FF) are ill-formed 831 default: 832 { 833 error_message = "invalid string: ill-formed UTF-8 byte"; 834 return token_type::parse_error; 835 } 836 } 837 } 838 } 839 840 /*! 841 * @brief scan a comment 842 * @return whether comment could be scanned successfully 843 */ scan_comment()844 bool scan_comment() 845 { 846 switch (get()) 847 { 848 // single-line comments skip input until a newline or EOF is read 849 case '/': 850 { 851 while (true) 852 { 853 switch (get()) 854 { 855 case '\n': 856 case '\r': 857 case std::char_traits<char_type>::eof(): 858 case '\0': 859 return true; 860 861 default: 862 break; 863 } 864 } 865 } 866 867 // multi-line comments skip input until */ is read 868 case '*': 869 { 870 while (true) 871 { 872 switch (get()) 873 { 874 case std::char_traits<char_type>::eof(): 875 case '\0': 876 { 877 error_message = "invalid comment; missing closing '*/'"; 878 return false; 879 } 880 881 case '*': 882 { 883 switch (get()) 884 { 885 case '/': 886 return true; 887 888 default: 889 { 890 unget(); 891 continue; 892 } 893 } 894 } 895 896 default: 897 continue; 898 } 899 } 900 } 901 902 // unexpected character after reading '/' 903 default: 904 { 905 error_message = "invalid comment; expecting '/' or '*' after '/'"; 906 return false; 907 } 908 } 909 } 910 911 JSON_HEDLEY_NON_NULL(2) strtof(float & f,const char * str,char ** endptr)912 static void strtof(float& f, const char* str, char** endptr) noexcept 913 { 914 f = std::strtof(str, endptr); 915 } 916 917 JSON_HEDLEY_NON_NULL(2) strtof(double & f,const char * str,char ** endptr)918 static void strtof(double& f, const char* str, char** endptr) noexcept 919 { 920 f = std::strtod(str, endptr); 921 } 922 923 JSON_HEDLEY_NON_NULL(2) strtof(long double & f,const char * str,char ** endptr)924 static void strtof(long double& f, const char* str, char** endptr) noexcept 925 { 926 f = std::strtold(str, endptr); 927 } 928 929 /*! 930 @brief scan a number literal 931 932 This function scans a string according to Sect. 6 of RFC 8259. 933 934 The function is realized with a deterministic finite state machine derived 935 from the grammar described in RFC 8259. Starting in state "init", the 936 input is read and used to determined the next state. Only state "done" 937 accepts the number. State "error" is a trap state to model errors. In the 938 table below, "anything" means any character but the ones listed before. 939 940 state | 0 | 1-9 | e E | + | - | . | anything 941 ---------|----------|----------|----------|---------|---------|----------|----------- 942 init | zero | any1 | [error] | [error] | minus | [error] | [error] 943 minus | zero | any1 | [error] | [error] | [error] | [error] | [error] 944 zero | done | done | exponent | done | done | decimal1 | done 945 any1 | any1 | any1 | exponent | done | done | decimal1 | done 946 decimal1 | decimal2 | decimal2 | [error] | [error] | [error] | [error] | [error] 947 decimal2 | decimal2 | decimal2 | exponent | done | done | done | done 948 exponent | any2 | any2 | [error] | sign | sign | [error] | [error] 949 sign | any2 | any2 | [error] | [error] | [error] | [error] | [error] 950 any2 | any2 | any2 | done | done | done | done | done 951 952 The state machine is realized with one label per state (prefixed with 953 "scan_number_") and `goto` statements between them. The state machine 954 contains cycles, but any cycle can be left when EOF is read. Therefore, 955 the function is guaranteed to terminate. 956 957 During scanning, the read bytes are stored in token_buffer. This string is 958 then converted to a signed integer, an unsigned integer, or a 959 floating-point number. 960 961 @return token_type::value_unsigned, token_type::value_integer, or 962 token_type::value_float if number could be successfully scanned, 963 token_type::parse_error otherwise 964 965 @note The scanner is independent of the current locale. Internally, the 966 locale's decimal point is used instead of `.` to work with the 967 locale-dependent converters. 968 */ scan_number()969 token_type scan_number() // lgtm [cpp/use-of-goto] 970 { 971 // reset token_buffer to store the number's bytes 972 reset(); 973 974 // the type of the parsed number; initially set to unsigned; will be 975 // changed if minus sign, decimal point or exponent is read 976 token_type number_type = token_type::value_unsigned; 977 978 // state (init): we just found out we need to scan a number 979 switch (current) 980 { 981 case '-': 982 { 983 add(current); 984 goto scan_number_minus; 985 } 986 987 case '0': 988 { 989 add(current); 990 goto scan_number_zero; 991 } 992 993 case '1': 994 case '2': 995 case '3': 996 case '4': 997 case '5': 998 case '6': 999 case '7': 1000 case '8': 1001 case '9': 1002 { 1003 add(current); 1004 goto scan_number_any1; 1005 } 1006 1007 // all other characters are rejected outside scan_number() 1008 default: // LCOV_EXCL_LINE 1009 JSON_ASSERT(false); // NOLINT(cert-dcl03-c,hicpp-static-assert,misc-static-assert) LCOV_EXCL_LINE 1010 } 1011 1012 scan_number_minus: 1013 // state: we just parsed a leading minus sign 1014 number_type = token_type::value_integer; 1015 switch (get()) 1016 { 1017 case '0': 1018 { 1019 add(current); 1020 goto scan_number_zero; 1021 } 1022 1023 case '1': 1024 case '2': 1025 case '3': 1026 case '4': 1027 case '5': 1028 case '6': 1029 case '7': 1030 case '8': 1031 case '9': 1032 { 1033 add(current); 1034 goto scan_number_any1; 1035 } 1036 1037 default: 1038 { 1039 error_message = "invalid number; expected digit after '-'"; 1040 return token_type::parse_error; 1041 } 1042 } 1043 1044 scan_number_zero: 1045 // state: we just parse a zero (maybe with a leading minus sign) 1046 switch (get()) 1047 { 1048 case '.': 1049 { 1050 add(decimal_point_char); 1051 goto scan_number_decimal1; 1052 } 1053 1054 case 'e': 1055 case 'E': 1056 { 1057 add(current); 1058 goto scan_number_exponent; 1059 } 1060 1061 default: 1062 goto scan_number_done; 1063 } 1064 1065 scan_number_any1: 1066 // state: we just parsed a number 0-9 (maybe with a leading minus sign) 1067 switch (get()) 1068 { 1069 case '0': 1070 case '1': 1071 case '2': 1072 case '3': 1073 case '4': 1074 case '5': 1075 case '6': 1076 case '7': 1077 case '8': 1078 case '9': 1079 { 1080 add(current); 1081 goto scan_number_any1; 1082 } 1083 1084 case '.': 1085 { 1086 add(decimal_point_char); 1087 goto scan_number_decimal1; 1088 } 1089 1090 case 'e': 1091 case 'E': 1092 { 1093 add(current); 1094 goto scan_number_exponent; 1095 } 1096 1097 default: 1098 goto scan_number_done; 1099 } 1100 1101 scan_number_decimal1: 1102 // state: we just parsed a decimal point 1103 number_type = token_type::value_float; 1104 switch (get()) 1105 { 1106 case '0': 1107 case '1': 1108 case '2': 1109 case '3': 1110 case '4': 1111 case '5': 1112 case '6': 1113 case '7': 1114 case '8': 1115 case '9': 1116 { 1117 add(current); 1118 goto scan_number_decimal2; 1119 } 1120 1121 default: 1122 { 1123 error_message = "invalid number; expected digit after '.'"; 1124 return token_type::parse_error; 1125 } 1126 } 1127 1128 scan_number_decimal2: 1129 // we just parsed at least one number after a decimal point 1130 switch (get()) 1131 { 1132 case '0': 1133 case '1': 1134 case '2': 1135 case '3': 1136 case '4': 1137 case '5': 1138 case '6': 1139 case '7': 1140 case '8': 1141 case '9': 1142 { 1143 add(current); 1144 goto scan_number_decimal2; 1145 } 1146 1147 case 'e': 1148 case 'E': 1149 { 1150 add(current); 1151 goto scan_number_exponent; 1152 } 1153 1154 default: 1155 goto scan_number_done; 1156 } 1157 1158 scan_number_exponent: 1159 // we just parsed an exponent 1160 number_type = token_type::value_float; 1161 switch (get()) 1162 { 1163 case '+': 1164 case '-': 1165 { 1166 add(current); 1167 goto scan_number_sign; 1168 } 1169 1170 case '0': 1171 case '1': 1172 case '2': 1173 case '3': 1174 case '4': 1175 case '5': 1176 case '6': 1177 case '7': 1178 case '8': 1179 case '9': 1180 { 1181 add(current); 1182 goto scan_number_any2; 1183 } 1184 1185 default: 1186 { 1187 error_message = 1188 "invalid number; expected '+', '-', or digit after exponent"; 1189 return token_type::parse_error; 1190 } 1191 } 1192 1193 scan_number_sign: 1194 // we just parsed an exponent sign 1195 switch (get()) 1196 { 1197 case '0': 1198 case '1': 1199 case '2': 1200 case '3': 1201 case '4': 1202 case '5': 1203 case '6': 1204 case '7': 1205 case '8': 1206 case '9': 1207 { 1208 add(current); 1209 goto scan_number_any2; 1210 } 1211 1212 default: 1213 { 1214 error_message = "invalid number; expected digit after exponent sign"; 1215 return token_type::parse_error; 1216 } 1217 } 1218 1219 scan_number_any2: 1220 // we just parsed a number after the exponent or exponent sign 1221 switch (get()) 1222 { 1223 case '0': 1224 case '1': 1225 case '2': 1226 case '3': 1227 case '4': 1228 case '5': 1229 case '6': 1230 case '7': 1231 case '8': 1232 case '9': 1233 { 1234 add(current); 1235 goto scan_number_any2; 1236 } 1237 1238 default: 1239 goto scan_number_done; 1240 } 1241 1242 scan_number_done: 1243 // unget the character after the number (we only read it to know that 1244 // we are done scanning a number) 1245 unget(); 1246 1247 char* endptr = nullptr; // NOLINT(cppcoreguidelines-pro-type-vararg,hicpp-vararg) 1248 errno = 0; 1249 1250 // try to parse integers first and fall back to floats 1251 if (number_type == token_type::value_unsigned) 1252 { 1253 const auto x = std::strtoull(token_buffer.data(), &endptr, 10); 1254 1255 // we checked the number format before 1256 JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size()); 1257 1258 if (errno == 0) 1259 { 1260 value_unsigned = static_cast<number_unsigned_t>(x); 1261 if (value_unsigned == x) 1262 { 1263 return token_type::value_unsigned; 1264 } 1265 } 1266 } 1267 else if (number_type == token_type::value_integer) 1268 { 1269 const auto x = std::strtoll(token_buffer.data(), &endptr, 10); 1270 1271 // we checked the number format before 1272 JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size()); 1273 1274 if (errno == 0) 1275 { 1276 value_integer = static_cast<number_integer_t>(x); 1277 if (value_integer == x) 1278 { 1279 return token_type::value_integer; 1280 } 1281 } 1282 } 1283 1284 // this code is reached if we parse a floating-point number or if an 1285 // integer conversion above failed 1286 strtof(value_float, token_buffer.data(), &endptr); 1287 1288 // we checked the number format before 1289 JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size()); 1290 1291 return token_type::value_float; 1292 } 1293 1294 /*! 1295 @param[in] literal_text the literal text to expect 1296 @param[in] length the length of the passed literal text 1297 @param[in] return_type the token type to return on success 1298 */ 1299 JSON_HEDLEY_NON_NULL(2) scan_literal(const char_type * literal_text,const std::size_t length,token_type return_type)1300 token_type scan_literal(const char_type* literal_text, const std::size_t length, 1301 token_type return_type) 1302 { 1303 JSON_ASSERT(std::char_traits<char_type>::to_char_type(current) == literal_text[0]); 1304 for (std::size_t i = 1; i < length; ++i) 1305 { 1306 if (JSON_HEDLEY_UNLIKELY(std::char_traits<char_type>::to_char_type(get()) != literal_text[i])) 1307 { 1308 error_message = "invalid literal"; 1309 return token_type::parse_error; 1310 } 1311 } 1312 return return_type; 1313 } 1314 1315 ///////////////////// 1316 // input management 1317 ///////////////////// 1318 1319 /// reset token_buffer; current character is beginning of token reset()1320 void reset() noexcept 1321 { 1322 token_buffer.clear(); 1323 token_string.clear(); 1324 token_string.push_back(std::char_traits<char_type>::to_char_type(current)); 1325 } 1326 1327 /* 1328 @brief get next character from the input 1329 1330 This function provides the interface to the used input adapter. It does 1331 not throw in case the input reached EOF, but returns a 1332 `std::char_traits<char>::eof()` in that case. Stores the scanned characters 1333 for use in error messages. 1334 1335 @return character read from the input 1336 */ get()1337 char_int_type get() 1338 { 1339 ++position.chars_read_total; 1340 ++position.chars_read_current_line; 1341 1342 if (next_unget) 1343 { 1344 // just reset the next_unget variable and work with current 1345 next_unget = false; 1346 } 1347 else 1348 { 1349 current = ia.get_character(); 1350 } 1351 1352 if (JSON_HEDLEY_LIKELY(current != std::char_traits<char_type>::eof())) 1353 { 1354 token_string.push_back(std::char_traits<char_type>::to_char_type(current)); 1355 } 1356 1357 if (current == '\n') 1358 { 1359 ++position.lines_read; 1360 position.chars_read_current_line = 0; 1361 } 1362 1363 return current; 1364 } 1365 1366 /*! 1367 @brief unget current character (read it again on next get) 1368 1369 We implement unget by setting variable next_unget to true. The input is not 1370 changed - we just simulate ungetting by modifying chars_read_total, 1371 chars_read_current_line, and token_string. The next call to get() will 1372 behave as if the unget character is read again. 1373 */ unget()1374 void unget() 1375 { 1376 next_unget = true; 1377 1378 --position.chars_read_total; 1379 1380 // in case we "unget" a newline, we have to also decrement the lines_read 1381 if (position.chars_read_current_line == 0) 1382 { 1383 if (position.lines_read > 0) 1384 { 1385 --position.lines_read; 1386 } 1387 } 1388 else 1389 { 1390 --position.chars_read_current_line; 1391 } 1392 1393 if (JSON_HEDLEY_LIKELY(current != std::char_traits<char_type>::eof())) 1394 { 1395 JSON_ASSERT(!token_string.empty()); 1396 token_string.pop_back(); 1397 } 1398 } 1399 1400 /// add a character to token_buffer add(char_int_type c)1401 void add(char_int_type c) 1402 { 1403 token_buffer.push_back(static_cast<typename string_t::value_type>(c)); 1404 } 1405 1406 public: 1407 ///////////////////// 1408 // value getters 1409 ///////////////////// 1410 1411 /// return integer value get_number_integer() const1412 constexpr number_integer_t get_number_integer() const noexcept 1413 { 1414 return value_integer; 1415 } 1416 1417 /// return unsigned integer value get_number_unsigned() const1418 constexpr number_unsigned_t get_number_unsigned() const noexcept 1419 { 1420 return value_unsigned; 1421 } 1422 1423 /// return floating-point value get_number_float() const1424 constexpr number_float_t get_number_float() const noexcept 1425 { 1426 return value_float; 1427 } 1428 1429 /// return current string value (implicitly resets the token; useful only once) get_string()1430 string_t& get_string() 1431 { 1432 return token_buffer; 1433 } 1434 1435 ///////////////////// 1436 // diagnostics 1437 ///////////////////// 1438 1439 /// return position of last read token get_position() const1440 constexpr position_t get_position() const noexcept 1441 { 1442 return position; 1443 } 1444 1445 /// return the last read token (for errors only). Will never contain EOF 1446 /// (an arbitrary value that is not a valid char value, often -1), because 1447 /// 255 may legitimately occur. May contain NUL, which should be escaped. get_token_string() const1448 std::string get_token_string() const 1449 { 1450 // escape control characters 1451 std::string result; 1452 for (const auto c : token_string) 1453 { 1454 if (static_cast<unsigned char>(c) <= '\x1F') 1455 { 1456 // escape control characters 1457 std::array<char, 9> cs{{}}; 1458 static_cast<void>((std::snprintf)(cs.data(), cs.size(), "<U+%.4X>", static_cast<unsigned char>(c))); // NOLINT(cppcoreguidelines-pro-type-vararg,hicpp-vararg) 1459 result += cs.data(); 1460 } 1461 else 1462 { 1463 // add character as is 1464 result.push_back(static_cast<std::string::value_type>(c)); 1465 } 1466 } 1467 1468 return result; 1469 } 1470 1471 /// return syntax error message 1472 JSON_HEDLEY_RETURNS_NON_NULL get_error_message() const1473 constexpr const char* get_error_message() const noexcept 1474 { 1475 return error_message; 1476 } 1477 1478 ///////////////////// 1479 // actual scanner 1480 ///////////////////// 1481 1482 /*! 1483 @brief skip the UTF-8 byte order mark 1484 @return true iff there is no BOM or the correct BOM has been skipped 1485 */ skip_bom()1486 bool skip_bom() 1487 { 1488 if (get() == 0xEF) 1489 { 1490 // check if we completely parse the BOM 1491 return get() == 0xBB && get() == 0xBF; 1492 } 1493 1494 // the first character is not the beginning of the BOM; unget it to 1495 // process is later 1496 unget(); 1497 return true; 1498 } 1499 skip_whitespace()1500 void skip_whitespace() 1501 { 1502 do 1503 { 1504 get(); 1505 } 1506 while (current == ' ' || current == '\t' || current == '\n' || current == '\r'); 1507 } 1508 scan()1509 token_type scan() 1510 { 1511 // initially, skip the BOM 1512 if (position.chars_read_total == 0 && !skip_bom()) 1513 { 1514 error_message = "invalid BOM; must be 0xEF 0xBB 0xBF if given"; 1515 return token_type::parse_error; 1516 } 1517 1518 // read next character and ignore whitespace 1519 skip_whitespace(); 1520 1521 // ignore comments 1522 while (ignore_comments && current == '/') 1523 { 1524 if (!scan_comment()) 1525 { 1526 return token_type::parse_error; 1527 } 1528 1529 // skip following whitespace 1530 skip_whitespace(); 1531 } 1532 1533 switch (current) 1534 { 1535 // structural characters 1536 case '[': 1537 return token_type::begin_array; 1538 case ']': 1539 return token_type::end_array; 1540 case '{': 1541 return token_type::begin_object; 1542 case '}': 1543 return token_type::end_object; 1544 case ':': 1545 return token_type::name_separator; 1546 case ',': 1547 return token_type::value_separator; 1548 1549 // literals 1550 case 't': 1551 { 1552 std::array<char_type, 4> true_literal = {{static_cast<char_type>('t'), static_cast<char_type>('r'), static_cast<char_type>('u'), static_cast<char_type>('e')}}; 1553 return scan_literal(true_literal.data(), true_literal.size(), token_type::literal_true); 1554 } 1555 case 'f': 1556 { 1557 std::array<char_type, 5> false_literal = {{static_cast<char_type>('f'), static_cast<char_type>('a'), static_cast<char_type>('l'), static_cast<char_type>('s'), static_cast<char_type>('e')}}; 1558 return scan_literal(false_literal.data(), false_literal.size(), token_type::literal_false); 1559 } 1560 case 'n': 1561 { 1562 std::array<char_type, 4> null_literal = {{static_cast<char_type>('n'), static_cast<char_type>('u'), static_cast<char_type>('l'), static_cast<char_type>('l')}}; 1563 return scan_literal(null_literal.data(), null_literal.size(), token_type::literal_null); 1564 } 1565 1566 // string 1567 case '\"': 1568 return scan_string(); 1569 1570 // number 1571 case '-': 1572 case '0': 1573 case '1': 1574 case '2': 1575 case '3': 1576 case '4': 1577 case '5': 1578 case '6': 1579 case '7': 1580 case '8': 1581 case '9': 1582 return scan_number(); 1583 1584 // end of input (the null byte is needed when parsing from 1585 // string literals) 1586 case '\0': 1587 case std::char_traits<char_type>::eof(): 1588 return token_type::end_of_input; 1589 1590 // error 1591 default: 1592 error_message = "invalid literal"; 1593 return token_type::parse_error; 1594 } 1595 } 1596 1597 private: 1598 /// input adapter 1599 InputAdapterType ia; 1600 1601 /// whether comments should be ignored (true) or signaled as errors (false) 1602 const bool ignore_comments = false; 1603 1604 /// the current character 1605 char_int_type current = std::char_traits<char_type>::eof(); 1606 1607 /// whether the next get() call should just return current 1608 bool next_unget = false; 1609 1610 /// the start position of the current token 1611 position_t position {}; 1612 1613 /// raw input token string (for error messages) 1614 std::vector<char_type> token_string {}; 1615 1616 /// buffer for variable-length tokens (numbers, strings) 1617 string_t token_buffer {}; 1618 1619 /// a description of occurred lexer errors 1620 const char* error_message = ""; 1621 1622 // number values 1623 number_integer_t value_integer = 0; 1624 number_unsigned_t value_unsigned = 0; 1625 number_float_t value_float = 0; 1626 1627 /// the decimal point 1628 const char_int_type decimal_point_char = '.'; 1629 }; 1630 1631 } // namespace detail 1632 NLOHMANN_JSON_NAMESPACE_END 1633