source-map-consumer.js 39.6 KB
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145
/* -*- Mode: js; js-indent-level: 2; -*- */
/*
 * Copyright 2011 Mozilla Foundation and contributors
 * Licensed under the New BSD license. See LICENSE or:
 * http://opensource.org/licenses/BSD-3-Clause
 */

var util = require('./util');
var binarySearch = require('./binary-search');
var ArraySet = require('./array-set').ArraySet;
var base64VLQ = require('./base64-vlq');
var quickSort = require('./quick-sort').quickSort;

function SourceMapConsumer(aSourceMap, aSourceMapURL) {
  var sourceMap = aSourceMap;
  if (typeof aSourceMap === 'string') {
    sourceMap = util.parseSourceMapInput(aSourceMap);
  }

  return sourceMap.sections != null
    ? new IndexedSourceMapConsumer(sourceMap, aSourceMapURL)
    : new BasicSourceMapConsumer(sourceMap, aSourceMapURL);
}

SourceMapConsumer.fromSourceMap = function(aSourceMap, aSourceMapURL) {
  return BasicSourceMapConsumer.fromSourceMap(aSourceMap, aSourceMapURL);
}

/**
 * The version of the source mapping spec that we are consuming.
 */
SourceMapConsumer.prototype._version = 3;

// `__generatedMappings` and `__originalMappings` are arrays that hold the
// parsed mapping coordinates from the source map's "mappings" attribute. They
// are lazily instantiated, accessed via the `_generatedMappings` and
// `_originalMappings` getters respectively, and we only parse the mappings
// and create these arrays once queried for a source location. We jump through
// these hoops because there can be many thousands of mappings, and parsing
// them is expensive, so we only want to do it if we must.
//
// Each object in the arrays is of the form:
//
//     {
//       generatedLine: The line number in the generated code,
//       generatedColumn: The column number in the generated code,
//       source: The path to the original source file that generated this
//               chunk of code,
//       originalLine: The line number in the original source that
//                     corresponds to this chunk of generated code,
//       originalColumn: The column number in the original source that
//                       corresponds to this chunk of generated code,
//       name: The name of the original symbol which generated this chunk of
//             code.
//     }
//
// All properties except for `generatedLine` and `generatedColumn` can be
// `null`.
//
// `_generatedMappings` is ordered by the generated positions.
//
// `_originalMappings` is ordered by the original positions.

SourceMapConsumer.prototype.__generatedMappings = null;
Object.defineProperty(SourceMapConsumer.prototype, '_generatedMappings', {
  configurable: true,
  enumerable: true,
  get: function () {
    if (!this.__generatedMappings) {
      this._parseMappings(this._mappings, this.sourceRoot);
    }

    return this.__generatedMappings;
  }
});

SourceMapConsumer.prototype.__originalMappings = null;
Object.defineProperty(SourceMapConsumer.prototype, '_originalMappings', {
  configurable: true,
  enumerable: true,
  get: function () {
    if (!this.__originalMappings) {
      this._parseMappings(this._mappings, this.sourceRoot);
    }

    return this.__originalMappings;
  }
});

SourceMapConsumer.prototype._charIsMappingSeparator =
  function SourceMapConsumer_charIsMappingSeparator(aStr, index) {
    var c = aStr.charAt(index);
    return c === ";" || c === ",";
  };

/**
 * Parse the mappings in a string in to a data structure which we can easily
 * query (the ordered arrays in the `this.__generatedMappings` and
 * `this.__originalMappings` properties).
 */
SourceMapConsumer.prototype._parseMappings =
  function SourceMapConsumer_parseMappings(aStr, aSourceRoot) {
    throw new Error("Subclasses must implement _parseMappings");
  };

SourceMapConsumer.GENERATED_ORDER = 1;
SourceMapConsumer.ORIGINAL_ORDER = 2;

SourceMapConsumer.GREATEST_LOWER_BOUND = 1;
SourceMapConsumer.LEAST_UPPER_BOUND = 2;

/**
 * Iterate over each mapping between an original source/line/column and a
 * generated line/column in this source map.
 *
 * @param Function aCallback
 *        The function that is called with each mapping.
 * @param Object aContext
 *        Optional. If specified, this object will be the value of `this` every
 *        time that `aCallback` is called.
 * @param aOrder
 *        Either `SourceMapConsumer.GENERATED_ORDER` or
 *        `SourceMapConsumer.ORIGINAL_ORDER`. Specifies whether you want to
 *        iterate over the mappings sorted by the generated file's line/column
 *        order or the original's source/line/column order, respectively. Defaults to
 *        `SourceMapConsumer.GENERATED_ORDER`.
 */
SourceMapConsumer.prototype.eachMapping =
  function SourceMapConsumer_eachMapping(aCallback, aContext, aOrder) {
    var context = aContext || null;
    var order = aOrder || SourceMapConsumer.GENERATED_ORDER;

    var mappings;
    switch (order) {
    case SourceMapConsumer.GENERATED_ORDER:
      mappings = this._generatedMappings;
      break;
    case SourceMapConsumer.ORIGINAL_ORDER:
      mappings = this._originalMappings;
      break;
    default:
      throw new Error("Unknown order of iteration.");
    }

    var sourceRoot = this.sourceRoot;
    mappings.map(function (mapping) {
      var source = mapping.source === null ? null : this._sources.at(mapping.source);
      source = util.computeSourceURL(sourceRoot, source, this._sourceMapURL);
      return {
        source: source,
        generatedLine: mapping.generatedLine,
        generatedColumn: mapping.generatedColumn,
        originalLine: mapping.originalLine,
        originalColumn: mapping.originalColumn,
        name: mapping.name === null ? null : this._names.at(mapping.name)
      };
    }, this).forEach(aCallback, context);
  };

/**
 * Returns all generated line and column information for the original source,
 * line, and column provided. If no column is provided, returns all mappings
 * corresponding to a either the line we are searching for or the next
 * closest line that has any mappings. Otherwise, returns all mappings
 * corresponding to the given line and either the column we are searching for
 * or the next closest column that has any offsets.
 *
 * The only argument is an object with the following properties:
 *
 *   - source: The filename of the original source.
 *   - line: The line number in the original source.  The line number is 1-based.
 *   - column: Optional. the column number in the original source.
 *    The column number is 0-based.
 *
 * and an array of objects is returned, each with the following properties:
 *
 *   - line: The line number in the generated source, or null.  The
 *    line number is 1-based.
 *   - column: The column number in the generated source, or null.
 *    The column number is 0-based.
 */
SourceMapConsumer.prototype.allGeneratedPositionsFor =
  function SourceMapConsumer_allGeneratedPositionsFor(aArgs) {
    var line = util.getArg(aArgs, 'line');

    // When there is no exact match, BasicSourceMapConsumer.prototype._findMapping
    // returns the index of the closest mapping less than the needle. By
    // setting needle.originalColumn to 0, we thus find the last mapping for
    // the given line, provided such a mapping exists.
    var needle = {
      source: util.getArg(aArgs, 'source'),
      originalLine: line,
      originalColumn: util.getArg(aArgs, 'column', 0)
    };

    needle.source = this._findSourceIndex(needle.source);
    if (needle.source < 0) {
      return [];
    }

    var mappings = [];

    var index = this._findMapping(needle,
                                  this._originalMappings,
                                  "originalLine",
                                  "originalColumn",
                                  util.compareByOriginalPositions,
                                  binarySearch.LEAST_UPPER_BOUND);
    if (index >= 0) {
      var mapping = this._originalMappings[index];

      if (aArgs.column === undefined) {
        var originalLine = mapping.originalLine;

        // Iterate until either we run out of mappings, or we run into
        // a mapping for a different line than the one we found. Since
        // mappings are sorted, this is guaranteed to find all mappings for
        // the line we found.
        while (mapping && mapping.originalLine === originalLine) {
          mappings.push({
            line: util.getArg(mapping, 'generatedLine', null),
            column: util.getArg(mapping, 'generatedColumn', null),
            lastColumn: util.getArg(mapping, 'lastGeneratedColumn', null)
          });

          mapping = this._originalMappings[++index];
        }
      } else {
        var originalColumn = mapping.originalColumn;

        // Iterate until either we run out of mappings, or we run into
        // a mapping for a different line than the one we were searching for.
        // Since mappings are sorted, this is guaranteed to find all mappings for
        // the line we are searching for.
        while (mapping &&
               mapping.originalLine === line &&
               mapping.originalColumn == originalColumn) {
          mappings.push({
            line: util.getArg(mapping, 'generatedLine', null),
            column: util.getArg(mapping, 'generatedColumn', null),
            lastColumn: util.getArg(mapping, 'lastGeneratedColumn', null)
          });

          mapping = this._originalMappings[++index];
        }
      }
    }

    return mappings;
  };

exports.SourceMapConsumer = SourceMapConsumer;

/**
 * A BasicSourceMapConsumer instance represents a parsed source map which we can
 * query for information about the original file positions by giving it a file
 * position in the generated source.
 *
 * The first parameter is the raw source map (either as a JSON string, or
 * already parsed to an object). According to the spec, source maps have the
 * following attributes:
 *
 *   - version: Which version of the source map spec this map is following.
 *   - sources: An array of URLs to the original source files.
 *   - names: An array of identifiers which can be referrenced by individual mappings.
 *   - sourceRoot: Optional. The URL root from which all sources are relative.
 *   - sourcesContent: Optional. An array of contents of the original source files.
 *   - mappings: A string of base64 VLQs which contain the actual mappings.
 *   - file: Optional. The generated file this source map is associated with.
 *
 * Here is an example source map, taken from the source map spec[0]:
 *
 *     {
 *       version : 3,
 *       file: "out.js",
 *       sourceRoot : "",
 *       sources: ["foo.js", "bar.js"],
 *       names: ["src", "maps", "are", "fun"],
 *       mappings: "AA,AB;;ABCDE;"
 *     }
 *
 * The second parameter, if given, is a string whose value is the URL
 * at which the source map was found.  This URL is used to compute the
 * sources array.
 *
 * [0]: https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit?pli=1#
 */
function BasicSourceMapConsumer(aSourceMap, aSourceMapURL) {
  var sourceMap = aSourceMap;
  if (typeof aSourceMap === 'string') {
    sourceMap = util.parseSourceMapInput(aSourceMap);
  }

  var version = util.getArg(sourceMap, 'version');
  var sources = util.getArg(sourceMap, 'sources');
  // Sass 3.3 leaves out the 'names' array, so we deviate from the spec (which
  // requires the array) to play nice here.
  var names = util.getArg(sourceMap, 'names', []);
  var sourceRoot = util.getArg(sourceMap, 'sourceRoot', null);
  var sourcesContent = util.getArg(sourceMap, 'sourcesContent', null);
  var mappings = util.getArg(sourceMap, 'mappings');
  var file = util.getArg(sourceMap, 'file', null);

  // Once again, Sass deviates from the spec and supplies the version as a
  // string rather than a number, so we use loose equality checking here.
  if (version != this._version) {
    throw new Error('Unsupported version: ' + version);
  }

  if (sourceRoot) {
    sourceRoot = util.normalize(sourceRoot);
  }

  sources = sources
    .map(String)
    // Some source maps produce relative source paths like "./foo.js" instead of
    // "foo.js".  Normalize these first so that future comparisons will succeed.
    // See bugzil.la/1090768.
    .map(util.normalize)
    // Always ensure that absolute sources are internally stored relative to
    // the source root, if the source root is absolute. Not doing this would
    // be particularly problematic when the source root is a prefix of the
    // source (valid, but why??). See github issue #199 and bugzil.la/1188982.
    .map(function (source) {
      return sourceRoot && util.isAbsolute(sourceRoot) && util.isAbsolute(source)
        ? util.relative(sourceRoot, source)
        : source;
    });

  // Pass `true` below to allow duplicate names and sources. While source maps
  // are intended to be compressed and deduplicated, the TypeScript compiler
  // sometimes generates source maps with duplicates in them. See Github issue
  // #72 and bugzil.la/889492.
  this._names = ArraySet.fromArray(names.map(String), true);
  this._sources = ArraySet.fromArray(sources, true);

  this._absoluteSources = this._sources.toArray().map(function (s) {
    return util.computeSourceURL(sourceRoot, s, aSourceMapURL);
  });

  this.sourceRoot = sourceRoot;
  this.sourcesContent = sourcesContent;
  this._mappings = mappings;
  this._sourceMapURL = aSourceMapURL;
  this.file = file;
}

BasicSourceMapConsumer.prototype = Object.create(SourceMapConsumer.prototype);
BasicSourceMapConsumer.prototype.consumer = SourceMapConsumer;

/**
 * Utility function to find the index of a source.  Returns -1 if not
 * found.
 */
BasicSourceMapConsumer.prototype._findSourceIndex = function(aSource) {
  var relativeSource = aSource;
  if (this.sourceRoot != null) {
    relativeSource = util.relative(this.sourceRoot, relativeSource);
  }

  if (this._sources.has(relativeSource)) {
    return this._sources.indexOf(relativeSource);
  }

  // Maybe aSource is an absolute URL as returned by |sources|.  In
  // this case we can't simply undo the transform.
  var i;
  for (i = 0; i < this._absoluteSources.length; ++i) {
    if (this._absoluteSources[i] == aSource) {
      return i;
    }
  }

  return -1;
};

/**
 * Create a BasicSourceMapConsumer from a SourceMapGenerator.
 *
 * @param SourceMapGenerator aSourceMap
 *        The source map that will be consumed.
 * @param String aSourceMapURL
 *        The URL at which the source map can be found (optional)
 * @returns BasicSourceMapConsumer
 */
BasicSourceMapConsumer.fromSourceMap =
  function SourceMapConsumer_fromSourceMap(aSourceMap, aSourceMapURL) {
    var smc = Object.create(BasicSourceMapConsumer.prototype);

    var names = smc._names = ArraySet.fromArray(aSourceMap._names.toArray(), true);
    var sources = smc._sources = ArraySet.fromArray(aSourceMap._sources.toArray(), true);
    smc.sourceRoot = aSourceMap._sourceRoot;
    smc.sourcesContent = aSourceMap._generateSourcesContent(smc._sources.toArray(),
                                                            smc.sourceRoot);
    smc.file = aSourceMap._file;
    smc._sourceMapURL = aSourceMapURL;
    smc._absoluteSources = smc._sources.toArray().map(function (s) {
      return util.computeSourceURL(smc.sourceRoot, s, aSourceMapURL);
    });

    // Because we are modifying the entries (by converting string sources and
    // names to indices into the sources and names ArraySets), we have to make
    // a copy of the entry or else bad things happen. Shared mutable state
    // strikes again! See github issue #191.

    var generatedMappings = aSourceMap._mappings.toArray().slice();
    var destGeneratedMappings = smc.__generatedMappings = [];
    var destOriginalMappings = smc.__originalMappings = [];

    for (var i = 0, length = generatedMappings.length; i < length; i++) {
      var srcMapping = generatedMappings[i];
      var destMapping = new Mapping;
      destMapping.generatedLine = srcMapping.generatedLine;
      destMapping.generatedColumn = srcMapping.generatedColumn;

      if (srcMapping.source) {
        destMapping.source = sources.indexOf(srcMapping.source);
        destMapping.originalLine = srcMapping.originalLine;
        destMapping.originalColumn = srcMapping.originalColumn;

        if (srcMapping.name) {
          destMapping.name = names.indexOf(srcMapping.name);
        }

        destOriginalMappings.push(destMapping);
      }

      destGeneratedMappings.push(destMapping);
    }

    quickSort(smc.__originalMappings, util.compareByOriginalPositions);

    return smc;
  };

/**
 * The version of the source mapping spec that we are consuming.
 */
BasicSourceMapConsumer.prototype._version = 3;

/**
 * The list of original sources.
 */
Object.defineProperty(BasicSourceMapConsumer.prototype, 'sources', {
  get: function () {
    return this._absoluteSources.slice();
  }
});

/**
 * Provide the JIT with a nice shape / hidden class.
 */
function Mapping() {
  this.generatedLine = 0;
  this.generatedColumn = 0;
  this.source = null;
  this.originalLine = null;
  this.originalColumn = null;
  this.name = null;
}

/**
 * Parse the mappings in a string in to a data structure which we can easily
 * query (the ordered arrays in the `this.__generatedMappings` and
 * `this.__originalMappings` properties).
 */
BasicSourceMapConsumer.prototype._parseMappings =
  function SourceMapConsumer_parseMappings(aStr, aSourceRoot) {
    var generatedLine = 1;
    var previousGeneratedColumn = 0;
    var previousOriginalLine = 0;
    var previousOriginalColumn = 0;
    var previousSource = 0;
    var previousName = 0;
    var length = aStr.length;
    var index = 0;
    var cachedSegments = {};
    var temp = {};
    var originalMappings = [];
    var generatedMappings = [];
    var mapping, str, segment, end, value;

    while (index < length) {
      if (aStr.charAt(index) === ';') {
        generatedLine++;
        index++;
        previousGeneratedColumn = 0;
      }
      else if (aStr.charAt(index) === ',') {
        index++;
      }
      else {
        mapping = new Mapping();
        mapping.generatedLine = generatedLine;

        // Because each offset is encoded relative to the previous one,
        // many segments often have the same encoding. We can exploit this
        // fact by caching the parsed variable length fields of each segment,
        // allowing us to avoid a second parse if we encounter the same
        // segment again.
        for (end = index; end < length; end++) {
          if (this._charIsMappingSeparator(aStr, end)) {
            break;
          }
        }
        str = aStr.slice(index, end);

        segment = cachedSegments[str];
        if (segment) {
          index += str.length;
        } else {
          segment = [];
          while (index < end) {
            base64VLQ.decode(aStr, index, temp);
            value = temp.value;
            index = temp.rest;
            segment.push(value);
          }

          if (segment.length === 2) {
            throw new Error('Found a source, but no line and column');
          }

          if (segment.length === 3) {
            throw new Error('Found a source and line, but no column');
          }

          cachedSegments[str] = segment;
        }

        // Generated column.
        mapping.generatedColumn = previousGeneratedColumn + segment[0];
        previousGeneratedColumn = mapping.generatedColumn;

        if (segment.length > 1) {
          // Original source.
          mapping.source = previousSource + segment[1];
          previousSource += segment[1];

          // Original line.
          mapping.originalLine = previousOriginalLine + segment[2];
          previousOriginalLine = mapping.originalLine;
          // Lines are stored 0-based
          mapping.originalLine += 1;

          // Original column.
          mapping.originalColumn = previousOriginalColumn + segment[3];
          previousOriginalColumn = mapping.originalColumn;

          if (segment.length > 4) {
            // Original name.
            mapping.name = previousName + segment[4];
            previousName += segment[4];
          }
        }

        generatedMappings.push(mapping);
        if (typeof mapping.originalLine === 'number') {
          originalMappings.push(mapping);
        }
      }
    }

    quickSort(generatedMappings, util.compareByGeneratedPositionsDeflated);
    this.__generatedMappings = generatedMappings;

    quickSort(originalMappings, util.compareByOriginalPositions);
    this.__originalMappings = originalMappings;
  };

/**
 * Find the mapping that best matches the hypothetical "needle" mapping that
 * we are searching for in the given "haystack" of mappings.
 */
BasicSourceMapConsumer.prototype._findMapping =
  function SourceMapConsumer_findMapping(aNeedle, aMappings, aLineName,
                                         aColumnName, aComparator, aBias) {
    // To return the position we are searching for, we must first find the
    // mapping for the given position and then return the opposite position it
    // points to. Because the mappings are sorted, we can use binary search to
    // find the best mapping.

    if (aNeedle[aLineName] <= 0) {
      throw new TypeError('Line must be greater than or equal to 1, got '
                          + aNeedle[aLineName]);
    }
    if (aNeedle[aColumnName] < 0) {
      throw new TypeError('Column must be greater than or equal to 0, got '
                          + aNeedle[aColumnName]);
    }

    return binarySearch.search(aNeedle, aMappings, aComparator, aBias);
  };

/**
 * Compute the last column for each generated mapping. The last column is
 * inclusive.
 */
BasicSourceMapConsumer.prototype.computeColumnSpans =
  function SourceMapConsumer_computeColumnSpans() {
    for (var index = 0; index < this._generatedMappings.length; ++index) {
      var mapping = this._generatedMappings[index];

      // Mappings do not contain a field for the last generated columnt. We
      // can come up with an optimistic estimate, however, by assuming that
      // mappings are contiguous (i.e. given two consecutive mappings, the
      // first mapping ends where the second one starts).
      if (index + 1 < this._generatedMappings.length) {
        var nextMapping = this._generatedMappings[index + 1];

        if (mapping.generatedLine === nextMapping.generatedLine) {
          mapping.lastGeneratedColumn = nextMapping.generatedColumn - 1;
          continue;
        }
      }

      // The last mapping for each line spans the entire line.
      mapping.lastGeneratedColumn = Infinity;
    }
  };

/**
 * Returns the original source, line, and column information for the generated
 * source's line and column positions provided. The only argument is an object
 * with the following properties:
 *
 *   - line: The line number in the generated source.  The line number
 *     is 1-based.
 *   - column: The column number in the generated source.  The column
 *     number is 0-based.
 *   - bias: Either 'SourceMapConsumer.GREATEST_LOWER_BOUND' or
 *     'SourceMapConsumer.LEAST_UPPER_BOUND'. Specifies whether to return the
 *     closest element that is smaller than or greater than the one we are
 *     searching for, respectively, if the exact element cannot be found.
 *     Defaults to 'SourceMapConsumer.GREATEST_LOWER_BOUND'.
 *
 * and an object is returned with the following properties:
 *
 *   - source: The original source file, or null.
 *   - line: The line number in the original source, or null.  The
 *     line number is 1-based.
 *   - column: The column number in the original source, or null.  The
 *     column number is 0-based.
 *   - name: The original identifier, or null.
 */
BasicSourceMapConsumer.prototype.originalPositionFor =
  function SourceMapConsumer_originalPositionFor(aArgs) {
    var needle = {
      generatedLine: util.getArg(aArgs, 'line'),
      generatedColumn: util.getArg(aArgs, 'column')
    };

    var index = this._findMapping(
      needle,
      this._generatedMappings,
      "generatedLine",
      "generatedColumn",
      util.compareByGeneratedPositionsDeflated,
      util.getArg(aArgs, 'bias', SourceMapConsumer.GREATEST_LOWER_BOUND)
    );

    if (index >= 0) {
      var mapping = this._generatedMappings[index];

      if (mapping.generatedLine === needle.generatedLine) {
        var source = util.getArg(mapping, 'source', null);
        if (source !== null) {
          source = this._sources.at(source);
          source = util.computeSourceURL(this.sourceRoot, source, this._sourceMapURL);
        }
        var name = util.getArg(mapping, 'name', null);
        if (name !== null) {
          name = this._names.at(name);
        }
        return {
          source: source,
          line: util.getArg(mapping, 'originalLine', null),
          column: util.getArg(mapping, 'originalColumn', null),
          name: name
        };
      }
    }

    return {
      source: null,
      line: null,
      column: null,
      name: null
    };
  };

/**
 * Return true if we have the source content for every source in the source
 * map, false otherwise.
 */
BasicSourceMapConsumer.prototype.hasContentsOfAllSources =
  function BasicSourceMapConsumer_hasContentsOfAllSources() {
    if (!this.sourcesContent) {
      return false;
    }
    return this.sourcesContent.length >= this._sources.size() &&
      !this.sourcesContent.some(function (sc) { return sc == null; });
  };

/**
 * Returns the original source content. The only argument is the url of the
 * original source file. Returns null if no original source content is
 * available.
 */
BasicSourceMapConsumer.prototype.sourceContentFor =
  function SourceMapConsumer_sourceContentFor(aSource, nullOnMissing) {
    if (!this.sourcesContent) {
      return null;
    }

    var index = this._findSourceIndex(aSource);
    if (index >= 0) {
      return this.sourcesContent[index];
    }

    var relativeSource = aSource;
    if (this.sourceRoot != null) {
      relativeSource = util.relative(this.sourceRoot, relativeSource);
    }

    var url;
    if (this.sourceRoot != null
        && (url = util.urlParse(this.sourceRoot))) {
      // XXX: file:// URIs and absolute paths lead to unexpected behavior for
      // many users. We can help them out when they expect file:// URIs to
      // behave like it would if they were running a local HTTP server. See
      // https://bugzilla.mozilla.org/show_bug.cgi?id=885597.
      var fileUriAbsPath = relativeSource.replace(/^file:\/\//, "");
      if (url.scheme == "file"
          && this._sources.has(fileUriAbsPath)) {
        return this.sourcesContent[this._sources.indexOf(fileUriAbsPath)]
      }

      if ((!url.path || url.path == "/")
          && this._sources.has("/" + relativeSource)) {
        return this.sourcesContent[this._sources.indexOf("/" + relativeSource)];
      }
    }

    // This function is used recursively from
    // IndexedSourceMapConsumer.prototype.sourceContentFor. In that case, we
    // don't want to throw if we can't find the source - we just want to
    // return null, so we provide a flag to exit gracefully.
    if (nullOnMissing) {
      return null;
    }
    else {
      throw new Error('"' + relativeSource + '" is not in the SourceMap.');
    }
  };

/**
 * Returns the generated line and column information for the original source,
 * line, and column positions provided. The only argument is an object with
 * the following properties:
 *
 *   - source: The filename of the original source.
 *   - line: The line number in the original source.  The line number
 *     is 1-based.
 *   - column: The column number in the original source.  The column
 *     number is 0-based.
 *   - bias: Either 'SourceMapConsumer.GREATEST_LOWER_BOUND' or
 *     'SourceMapConsumer.LEAST_UPPER_BOUND'. Specifies whether to return the
 *     closest element that is smaller than or greater than the one we are
 *     searching for, respectively, if the exact element cannot be found.
 *     Defaults to 'SourceMapConsumer.GREATEST_LOWER_BOUND'.
 *
 * and an object is returned with the following properties:
 *
 *   - line: The line number in the generated source, or null.  The
 *     line number is 1-based.
 *   - column: The column number in the generated source, or null.
 *     The column number is 0-based.
 */
BasicSourceMapConsumer.prototype.generatedPositionFor =
  function SourceMapConsumer_generatedPositionFor(aArgs) {
    var source = util.getArg(aArgs, 'source');
    source = this._findSourceIndex(source);
    if (source < 0) {
      return {
        line: null,
        column: null,
        lastColumn: null
      };
    }

    var needle = {
      source: source,
      originalLine: util.getArg(aArgs, 'line'),
      originalColumn: util.getArg(aArgs, 'column')
    };

    var index = this._findMapping(
      needle,
      this._originalMappings,
      "originalLine",
      "originalColumn",
      util.compareByOriginalPositions,
      util.getArg(aArgs, 'bias', SourceMapConsumer.GREATEST_LOWER_BOUND)
    );

    if (index >= 0) {
      var mapping = this._originalMappings[index];

      if (mapping.source === needle.source) {
        return {
          line: util.getArg(mapping, 'generatedLine', null),
          column: util.getArg(mapping, 'generatedColumn', null),
          lastColumn: util.getArg(mapping, 'lastGeneratedColumn', null)
        };
      }
    }

    return {
      line: null,
      column: null,
      lastColumn: null
    };
  };

exports.BasicSourceMapConsumer = BasicSourceMapConsumer;

/**
 * An IndexedSourceMapConsumer instance represents a parsed source map which
 * we can query for information. It differs from BasicSourceMapConsumer in
 * that it takes "indexed" source maps (i.e. ones with a "sections" field) as
 * input.
 *
 * The first parameter is a raw source map (either as a JSON string, or already
 * parsed to an object). According to the spec for indexed source maps, they
 * have the following attributes:
 *
 *   - version: Which version of the source map spec this map is following.
 *   - file: Optional. The generated file this source map is associated with.
 *   - sections: A list of section definitions.
 *
 * Each value under the "sections" field has two fields:
 *   - offset: The offset into the original specified at which this section
 *       begins to apply, defined as an object with a "line" and "column"
 *       field.
 *   - map: A source map definition. This source map could also be indexed,
 *       but doesn't have to be.
 *
 * Instead of the "map" field, it's also possible to have a "url" field
 * specifying a URL to retrieve a source map from, but that's currently
 * unsupported.
 *
 * Here's an example source map, taken from the source map spec[0], but
 * modified to omit a section which uses the "url" field.
 *
 *  {
 *    version : 3,
 *    file: "app.js",
 *    sections: [{
 *      offset: {line:100, column:10},
 *      map: {
 *        version : 3,
 *        file: "section.js",
 *        sources: ["foo.js", "bar.js"],
 *        names: ["src", "maps", "are", "fun"],
 *        mappings: "AAAA,E;;ABCDE;"
 *      }
 *    }],
 *  }
 *
 * The second parameter, if given, is a string whose value is the URL
 * at which the source map was found.  This URL is used to compute the
 * sources array.
 *
 * [0]: https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit#heading=h.535es3xeprgt
 */
function IndexedSourceMapConsumer(aSourceMap, aSourceMapURL) {
  var sourceMap = aSourceMap;
  if (typeof aSourceMap === 'string') {
    sourceMap = util.parseSourceMapInput(aSourceMap);
  }

  var version = util.getArg(sourceMap, 'version');
  var sections = util.getArg(sourceMap, 'sections');

  if (version != this._version) {
    throw new Error('Unsupported version: ' + version);
  }

  this._sources = new ArraySet();
  this._names = new ArraySet();

  var lastOffset = {
    line: -1,
    column: 0
  };
  this._sections = sections.map(function (s) {
    if (s.url) {
      // The url field will require support for asynchronicity.
      // See https://github.com/mozilla/source-map/issues/16
      throw new Error('Support for url field in sections not implemented.');
    }
    var offset = util.getArg(s, 'offset');
    var offsetLine = util.getArg(offset, 'line');
    var offsetColumn = util.getArg(offset, 'column');

    if (offsetLine < lastOffset.line ||
        (offsetLine === lastOffset.line && offsetColumn < lastOffset.column)) {
      throw new Error('Section offsets must be ordered and non-overlapping.');
    }
    lastOffset = offset;

    return {
      generatedOffset: {
        // The offset fields are 0-based, but we use 1-based indices when
        // encoding/decoding from VLQ.
        generatedLine: offsetLine + 1,
        generatedColumn: offsetColumn + 1
      },
      consumer: new SourceMapConsumer(util.getArg(s, 'map'), aSourceMapURL)
    }
  });
}

IndexedSourceMapConsumer.prototype = Object.create(SourceMapConsumer.prototype);
IndexedSourceMapConsumer.prototype.constructor = SourceMapConsumer;

/**
 * The version of the source mapping spec that we are consuming.
 */
IndexedSourceMapConsumer.prototype._version = 3;

/**
 * The list of original sources.
 */
Object.defineProperty(IndexedSourceMapConsumer.prototype, 'sources', {
  get: function () {
    var sources = [];
    for (var i = 0; i < this._sections.length; i++) {
      for (var j = 0; j < this._sections[i].consumer.sources.length; j++) {
        sources.push(this._sections[i].consumer.sources[j]);
      }
    }
    return sources;
  }
});

/**
 * Returns the original source, line, and column information for the generated
 * source's line and column positions provided. The only argument is an object
 * with the following properties:
 *
 *   - line: The line number in the generated source.  The line number
 *     is 1-based.
 *   - column: The column number in the generated source.  The column
 *     number is 0-based.
 *
 * and an object is returned with the following properties:
 *
 *   - source: The original source file, or null.
 *   - line: The line number in the original source, or null.  The
 *     line number is 1-based.
 *   - column: The column number in the original source, or null.  The
 *     column number is 0-based.
 *   - name: The original identifier, or null.
 */
IndexedSourceMapConsumer.prototype.originalPositionFor =
  function IndexedSourceMapConsumer_originalPositionFor(aArgs) {
    var needle = {
      generatedLine: util.getArg(aArgs, 'line'),
      generatedColumn: util.getArg(aArgs, 'column')
    };

    // Find the section containing the generated position we're trying to map
    // to an original position.
    var sectionIndex = binarySearch.search(needle, this._sections,
      function(needle, section) {
        var cmp = needle.generatedLine - section.generatedOffset.generatedLine;
        if (cmp) {
          return cmp;
        }

        return (needle.generatedColumn -
                section.generatedOffset.generatedColumn);
      });
    var section = this._sections[sectionIndex];

    if (!section) {
      return {
        source: null,
        line: null,
        column: null,
        name: null
      };
    }

    return section.consumer.originalPositionFor({
      line: needle.generatedLine -
        (section.generatedOffset.generatedLine - 1),
      column: needle.generatedColumn -
        (section.generatedOffset.generatedLine === needle.generatedLine
         ? section.generatedOffset.generatedColumn - 1
         : 0),
      bias: aArgs.bias
    });
  };

/**
 * Return true if we have the source content for every source in the source
 * map, false otherwise.
 */
IndexedSourceMapConsumer.prototype.hasContentsOfAllSources =
  function IndexedSourceMapConsumer_hasContentsOfAllSources() {
    return this._sections.every(function (s) {
      return s.consumer.hasContentsOfAllSources();
    });
  };

/**
 * Returns the original source content. The only argument is the url of the
 * original source file. Returns null if no original source content is
 * available.
 */
IndexedSourceMapConsumer.prototype.sourceContentFor =
  function IndexedSourceMapConsumer_sourceContentFor(aSource, nullOnMissing) {
    for (var i = 0; i < this._sections.length; i++) {
      var section = this._sections[i];

      var content = section.consumer.sourceContentFor(aSource, true);
      if (content) {
        return content;
      }
    }
    if (nullOnMissing) {
      return null;
    }
    else {
      throw new Error('"' + aSource + '" is not in the SourceMap.');
    }
  };

/**
 * Returns the generated line and column information for the original source,
 * line, and column positions provided. The only argument is an object with
 * the following properties:
 *
 *   - source: The filename of the original source.
 *   - line: The line number in the original source.  The line number
 *     is 1-based.
 *   - column: The column number in the original source.  The column
 *     number is 0-based.
 *
 * and an object is returned with the following properties:
 *
 *   - line: The line number in the generated source, or null.  The
 *     line number is 1-based. 
 *   - column: The column number in the generated source, or null.
 *     The column number is 0-based.
 */
IndexedSourceMapConsumer.prototype.generatedPositionFor =
  function IndexedSourceMapConsumer_generatedPositionFor(aArgs) {
    for (var i = 0; i < this._sections.length; i++) {
      var section = this._sections[i];

      // Only consider this section if the requested source is in the list of
      // sources of the consumer.
      if (section.consumer._findSourceIndex(util.getArg(aArgs, 'source')) === -1) {
        continue;
      }
      var generatedPosition = section.consumer.generatedPositionFor(aArgs);
      if (generatedPosition) {
        var ret = {
          line: generatedPosition.line +
            (section.generatedOffset.generatedLine - 1),
          column: generatedPosition.column +
            (section.generatedOffset.generatedLine === generatedPosition.line
             ? section.generatedOffset.generatedColumn - 1
             : 0)
        };
        return ret;
      }
    }

    return {
      line: null,
      column: null
    };
  };

/**
 * Parse the mappings in a string in to a data structure which we can easily
 * query (the ordered arrays in the `this.__generatedMappings` and
 * `this.__originalMappings` properties).
 */
IndexedSourceMapConsumer.prototype._parseMappings =
  function IndexedSourceMapConsumer_parseMappings(aStr, aSourceRoot) {
    this.__generatedMappings = [];
    this.__originalMappings = [];
    for (var i = 0; i < this._sections.length; i++) {
      var section = this._sections[i];
      var sectionMappings = section.consumer._generatedMappings;
      for (var j = 0; j < sectionMappings.length; j++) {
        var mapping = sectionMappings[j];

        var source = section.consumer._sources.at(mapping.source);
        source = util.computeSourceURL(section.consumer.sourceRoot, source, this._sourceMapURL);
        this._sources.add(source);
        source = this._sources.indexOf(source);

        var name = null;
        if (mapping.name) {
          name = section.consumer._names.at(mapping.name);
          this._names.add(name);
          name = this._names.indexOf(name);
        }

        // The mappings coming from the consumer for the section have
        // generated positions relative to the start of the section, so we
        // need to offset them to be relative to the start of the concatenated
        // generated file.
        var adjustedMapping = {
          source: source,
          generatedLine: mapping.generatedLine +
            (section.generatedOffset.generatedLine - 1),
          generatedColumn: mapping.generatedColumn +
            (section.generatedOffset.generatedLine === mapping.generatedLine
            ? section.generatedOffset.generatedColumn - 1
            : 0),
          originalLine: mapping.originalLine,
          originalColumn: mapping.originalColumn,
          name: name
        };

        this.__generatedMappings.push(adjustedMapping);
        if (typeof adjustedMapping.originalLine === 'number') {
          this.__originalMappings.push(adjustedMapping);
        }
      }
    }

    quickSort(this.__generatedMappings, util.compareByGeneratedPositionsDeflated);
    quickSort(this.__originalMappings, util.compareByOriginalPositions);
  };

exports.IndexedSourceMapConsumer = IndexedSourceMapConsumer;