Lady’s Gitweb - Pisces/blob - iri.js

   1 // ♓🌟 Piscēs ∷ iri.js
   2 // ====================================================================
   3 //
   4 // Copyright © 2020, 2022–2023 Lady [@ Lady’s Computer].
   5 //
   6 // This Source Code Form is subject to the terms of the Mozilla Public
   7 // License, v. 2.0. If a copy of the MPL was not distributed with this
   8 // file, You can obtain one at <https://mozilla.org/MPL/2.0/>.
   9
  10 import { push, splice } from "./collection.js";
  11 import { bind, call } from "./function.js";
  12 import { objectCreate } from "./object.js";
  13 import {
  14   asciiUppercase,
  15   getFirstSubstringIndex,
  16   getLastSubstringIndex,
  17   join,
  18   Matcher,
  19   rawString,
  20   stringStartsWith,
  21   substring,
  22 } from "./string.js";
  23 import { ITERATOR } from "./value.js";
  24
  25 const sub·delims = rawString`[!\$&'()*+,;=]`;
  26 const gen·delims = rawString`[:/?#\[\]@]`;
  27 //deno-lint-ignore no-unused-vars
  28 const reserved = rawString`${gen·delims}|${sub·delims}`;
  29 const unreserved = rawString`[A-Za-z0-9\-\._~]`;
  30 const pct·encoded = rawString`%[0-9A-Fa-f][0-9A-Fa-f]`;
  31 const dec·octet =
  32   rawString`[0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]`;
  33 const IPv4address =
  34   rawString`(?:${dec·octet})\.(?:${dec·octet})\.(?:${dec·octet})\.(?:${dec·octet})`;
  35 const h16 = rawString`[0-9A-Fa-f]{1,4}`;
  36 const ls32 = rawString`(?:${h16}):(?:${h16})|${IPv4address}`;
  37 const IPv6address =
  38   rawString`(?:(?:${h16}):){6}(?:${ls32})|::(?:(?:${h16}):){5}(?:${ls32})|(?:${h16})?::(?:(?:${h16}):){4}(?:${ls32})|(?:(?:(?:${h16}):){0,1}(?:${h16}))?::(?:(?:${h16}):){3}(?:${ls32})|(?:(?:(?:${h16}):){0,2}(?:${h16}))?::(?:(?:${h16}):){2}(?:${ls32})|(?:(?:(?:${h16}):){0,3}(?:${h16}))?::(?:${h16}):(?:${ls32})|(?:(?:(?:${h16}):){0,4}(?:${h16}))?::(?:${ls32})|(?:(?:(?:${h16}):){0,5}(?:${h16}))?::(?:${h16})|(?:(?:(?:${h16}):){0,6}(?:${h16}))?::`;
  39 const IPvFuture =
  40   rawString`v[0-9A-Fa-f]{1,}\.(?:${unreserved}|${sub·delims}|:)`;
  41 const IP·literal = rawString`\[(?:${IPv6address}|${IPvFuture})\]`;
  42 const port = rawString`[0-9]*`;
  43 const scheme = rawString`[A-Za-z][A-Za-z0-9+\-\.]*`;
  44 const pchar =
  45   rawString`${unreserved}|${pct·encoded}|${sub·delims}|[:@]`;
  46 const fragment = rawString`(?:${pchar}|[/?])*`;
  47 const query = rawString`(?:${pchar}|[/?])*`;
  48 const segment·nz·nc =
  49   rawString`(?:${unreserved}|${pct·encoded}|${sub·delims}|@)+`;
  50 const segment·nz = rawString`(?:${pchar})+`;
  51 const segment = rawString`(?:${pchar})*`;
  52 const path·empty = rawString``;
  53 const path·rootless = rawString`(?:${segment·nz})(?:/(?:${segment}))*`;
  54 const path·noscheme =
  55   rawString`(?:${segment·nz·nc})(?:/(?:${segment}))*`;
  56 const path·absolute =
  57   rawString`/(?:(?:${segment·nz})(?:/(?:${segment}))*)?`;
  58 const path·abempty = rawString`(?:/(?:${segment}))*`;
  59 const path =
  60   rawString`${path·abempty}|${path·absolute}|${path·noscheme}|${path·rootless}|${path·empty}`;
  61 const reg·name =
  62   rawString`(?:${unreserved}|${pct·encoded}|${sub·delims})*`;
  63 const host = rawString`${IP·literal}|${IPv4address}|${reg·name}`;
  64 const userinfo =
  65   rawString`(?:${unreserved}|${pct·encoded}|${sub·delims}|:)*`;
  66 const authority =
  67   rawString`(?:(?:${userinfo})@)?(?:${host})(?::(?:${port}))?`;
  68 const relative·part =
  69   rawString`//(?:${authority})(?:${path·abempty})|(?:${path·absolute})|(?:${path·noscheme})|(?:${path·empty})`;
  70 const relative·ref =
  71   rawString`(?:${relative·part})(?:\?(?:${query}))?(?:#(?:${fragment}))?`;
  72 const hier·part =
  73   rawString`//(?:${authority})(?:${path·abempty})|(?:${path·absolute})|(?:${path·rootless})|(?:${path·empty})`;
  74 const absolute·URI =
  75   rawString`(?:${scheme}):(?:${hier·part})(?:\?(?:${query}))?`;
  76 const URI =
  77   rawString`(?:${scheme}):(?:${hier·part})(?:\?(?:${query}))?(?:#(?:${fragment}))?`;
  78 const URI·reference = rawString`(?:${URI})|(?:${relative·ref})`;
  79
  80 const iprivate =
  81   rawString`[\u{E000}-\u{F8FF}\u{F0000}-\u{FFFFD}\u{100000}-\u{10FFFD}]`;
  82 const ucschar =
  83   rawString`[\u{A0}-\u{D7FF}\u{F900}-\u{FDCF}\u{FDF0}-\u{FFEF}\u{10000}-\u{1FFFD}\u{20000}-\u{2FFFD}\u{30000}-\u{3FFFD}\u{40000}-\u{4FFFD}\u{50000}-\u{5FFFD}\u{60000}-\u{6FFFD}\u{70000}-\u{7FFFD}\u{80000}-\u{8FFFD}\u{90000}-\u{9FFFD}\u{A0000}-\u{AFFFD}\u{B0000}-\u{BFFFD}\u{C0000}-\u{CFFFD}\u{D0000}-\u{DFFFD}\u{E0000}-\u{EFFFD}]`;
  84 const iunreserved = rawString`[A-Za-z0-9\-\._~]|${ucschar}`;
  85 const ipchar =
  86   rawString`${iunreserved}|${pct·encoded}|${sub·delims}|[:@]`;
  87 const ifragment = rawString`(?:${ipchar}|[/?])*`;
  88 const iquery = rawString`(?:${ipchar}|${iprivate}|[/?])*`;
  89 const isegment·nz·nc =
  90   rawString`(?:${iunreserved}|${pct·encoded}|${sub·delims}|@)+`;
  91 const isegment·nz = rawString`(?:${ipchar})+`;
  92 const isegment = rawString`(?:${ipchar})*`;
  93 const ipath·empty = rawString``;
  94 const ipath·rootless =
  95   rawString`(?:${isegment·nz})(?:/(?:${isegment}))*`;
  96 const ipath·noscheme =
  97   rawString`(?:${isegment·nz·nc})(?:/(?:${isegment}))*`;
  98 const ipath·absolute =
  99   rawString`/(?:(?:${isegment·nz})(?:/(?:${isegment}))*)?`;
 100 const ipath·abempty = rawString`(?:/(?:${isegment}))*`;
 101 const ipath =
 102   rawString`${ipath·abempty}|${ipath·absolute}|${ipath·noscheme}|${ipath·rootless}|${ipath·empty}`;
 103 const ireg·name =
 104   rawString`(?:${iunreserved}|${pct·encoded}|${sub·delims})*`;
 105 const ihost = rawString`${IP·literal}|${IPv4address}|${ireg·name}`;
 106 const iuserinfo =
 107   rawString`(?:${iunreserved}|${pct·encoded}|${sub·delims}|:)*`;
 108 const iauthority =
 109   rawString`(?:(?:${iuserinfo})@)?(?:${ihost})(?::(?:${port}))?`;
 110 const irelative·part =
 111   rawString`//(?:${iauthority})(?:${ipath·abempty})|(?:${ipath·absolute})|(?:${ipath·noscheme})|(?:${ipath·empty})`;
 112 const irelative·ref =
 113   rawString`(?:${irelative·part})(?:\?(?:${iquery}))?(?:#(?:${ifragment}))?`;
 114 const ihier·part =
 115   rawString`//(?:${iauthority})(?:${ipath·abempty})|(?:${ipath·absolute})|(?:${ipath·rootless})|(?:${ipath·empty})`;
 116 const absolute·IRI =
 117   rawString`(?:${scheme}):(?:${ihier·part})(?:\?(?:${iquery}))?`;
 118 const IRI =
 119   rawString`(?:${scheme}):(?:${ihier·part})(?:\?(?:${iquery}))?(?:#(?:${ifragment}))?`;
 120 const IRI·reference = rawString`(?:${IRI})|(?:${irelative·ref})`;
 121
 122 const leiri·iprivate =
 123   rawString`[\u{E000}-\u{F8FF}\u{E0000}-\u{E0FFF}\u{F0000}-\u{FFFFD}\u{100000}-\u{10FFFD}]`;
 124 const leiri·ucschar =
 125   rawString`[ <>"{}|\\^${"\x60"}\u{0}-\u{1F}\u{7F}-\u{D7FF}\u{E000}-\u{FFFD}\u{10000}-\u{10FFFF}]`;
 126 const leiri·iunreserved =
 127   rawString`[A-Za-z0-9\-\._~]|${leiri·ucschar}`;
 128 const leiri·ipchar =
 129   rawString`${leiri·iunreserved}|${pct·encoded}|${sub·delims}|[:@]`;
 130 const leiri·ifragment = rawString`(?:${leiri·ipchar}|[/?])*`;
 131 const leiri·iquery =
 132   rawString`(?:${leiri·ipchar}|${leiri·iprivate}|[/?])*`;
 133 const leiri·isegment·nz·nc =
 134   rawString`(?:${leiri·iunreserved}|${pct·encoded}|${sub·delims}|@)+`;
 135 const leiri·isegment·nz = rawString`(?:${leiri·ipchar})+`;
 136 const leiri·isegment = rawString`(?:${leiri·ipchar})*`;
 137 const leiri·ipath·empty = rawString``;
 138 const leiri·ipath·rootless =
 139   rawString`(?:${leiri·isegment·nz})(?:/(?:${leiri·isegment}))*`;
 140 const leiri·ipath·noscheme =
 141   rawString`(?:${leiri·isegment·nz·nc})(?:/(?:${leiri·isegment}))*`;
 142 const leiri·ipath·absolute =
 143   rawString`/(?:(?:${leiri·isegment·nz})(?:/(?:${leiri·isegment}))*)?`;
 144 const leiri·ipath·abempty = rawString`(?:/(?:${leiri·isegment}))*`;
 145 const leiri·ipath =
 146   rawString`${leiri·ipath·abempty}|${leiri·ipath·absolute}|${leiri·ipath·noscheme}|${leiri·ipath·rootless}|${leiri·ipath·empty}`;
 147 const leiri·ireg·name =
 148   rawString`(?:${leiri·iunreserved}|${pct·encoded}|${sub·delims})*`;
 149 const leiri·ihost =
 150   rawString`${IP·literal}|${IPv4address}|${leiri·ireg·name}`;
 151 const leiri·iuserinfo =
 152   rawString`(?:${leiri·iunreserved}|${pct·encoded}|${sub·delims}|:)*`;
 153 const leiri·iauthority =
 154   rawString`(?:(?:${leiri·iuserinfo})@)?(?:${leiri·ihost})(?::(?:${port}))?`;
 155 const leiri·irelative·part =
 156   rawString`//(?:${leiri·iauthority})(?:${leiri·ipath·abempty})|(?:${leiri·ipath·absolute})|(?:${leiri·ipath·noscheme})|(?:${leiri·ipath·empty})`;
 157 const leiri·irelative·ref =
 158   rawString`(?:${leiri·irelative·part})(?:\?(?:${leiri·iquery}))?(?:#(?:${leiri·ifragment}))?`;
 159 const leiri·ihier·part =
 160   rawString`//(?:${leiri·iauthority})(?:${leiri·ipath·abempty})|(?:${leiri·ipath·absolute})|(?:${leiri·ipath·rootless})|(?:${leiri·ipath·empty})`;
 161 const absolute·LEIRI =
 162   rawString`(?:${scheme}):(?:${leiri·ihier·part})(?:\?(?:${leiri·iquery}))?`;
 163 const LEIRI =
 164   rawString`(?:${scheme}):(?:${leiri·ihier·part})(?:\?(?:${leiri·iquery}))?(?:#(?:${leiri·ifragment}))?`;
 165 const LEIRI·reference =
 166   rawString`(?:${LEIRI})|(?:${leiri·irelative·ref})`;
 167
 168 export const {
 169   /**
 170    * Recomposes an (L·E·)I·R·I reference from its component parts.
 171    *
 172    * See §5.3 of R·F·C 3986.
 173    */
 174   composeReference,
 175
 176   /**
 177    * Converts an L·E·I·R·I to the corresponding I·R·I by
 178    * percent‐encoding unsupported characters.
 179    *
 180    * This function is somewhat complex because the I·R·I syntax allows
 181    * private·use characters *only* in the query.
 182    */
 183   escapeForIRI,
 184
 185   /**
 186    * Converts an (L·E·)I·R·I to the corresponding U·R·I by
 187    * percent‐encoding unsupported characters.
 188    *
 189    * This does not punycode the authority.
 190    */
 191   escapeForURI,
 192
 193   /**
 194    * Removes all dot segments ("." or "..") from the provided
 195    * (L·E·)I·R·I.
 196    *
 197    * See §5.2.4 of R·F·C 3986.
 198    */
 199   removeDotSegments,
 200 } = (() => {
 201   const TE = TextEncoder;
 202   const { toString: numberToString } = Number.prototype;
 203   const { encode: teEncode } = TE.prototype;
 204
 205   const { [ITERATOR]: arrayIterator } = Array.prototype;
 206   const {
 207     next: arrayIteratorNext,
 208   } = Object.getPrototypeOf([][ITERATOR]());
 209   const {
 210     next: generatorIteratorNext,
 211   } = Object.getPrototypeOf(function* () {}.prototype);
 212   const { [ITERATOR]: stringIterator } = String.prototype;
 213   const {
 214     next: stringIteratorNext,
 215   } = Object.getPrototypeOf(""[ITERATOR]());
 216
 217   const iriCharacterIterablePrototype = {
 218     [ITERATOR]() {
 219       return {
 220         next: bind(
 221           stringIteratorNext,
 222           call(stringIterator, this.source, []),
 223           [],
 224         ),
 225       };
 226     },
 227   };
 228   const iriGeneratorIterablePrototype = {
 229     [ITERATOR]() {
 230       return {
 231         next: bind(generatorIteratorNext, this.generator(), []),
 232       };
 233     },
 234   };
 235   const iriSegmentIterablePrototype = {
 236     [ITERATOR]() {
 237       return {
 238         next: bind(
 239           arrayIteratorNext,
 240           call(arrayIterator, this.segments, []),
 241           [],
 242         ),
 243       };
 244     },
 245   };
 246
 247   return {
 248     composeReference: ($) =>
 249       join(
 250         objectCreate(
 251           iriGeneratorIterablePrototype,
 252           {
 253             generator: {
 254               value: function* () {
 255                 const { scheme, authority, path, query, fragment } = $;
 256                 if (scheme != null) {
 257                   // A scheme is present.
 258                   yield scheme;
 259                   yield ":";
 260                 } else {
 261                   // No scheme is present.
 262                   /* do nothing */
 263                 }
 264                 if (authority != null) {
 265                   // An authority is present.
 266                   yield "//";
 267                   yield authority;
 268                 } else {
 269                   // No authority is present.
 270                   /* do nothing */
 271                 }
 272                 yield path ?? "";
 273                 if (query != null) {
 274                   // A query is present.
 275                   yield "?";
 276                   yield query;
 277                 } else {
 278                   // No query is present.
 279                   /* do nothing */
 280                 }
 281                 if (fragment != null) {
 282                   // A fragment is present.
 283                   yield "#";
 284                   yield fragment;
 285                 } else {
 286                   // No fragment is present.
 287                   /* do nothing */
 288                 }
 289               },
 290             },
 291           },
 292         ),
 293         "",
 294       ),
 295     escapeForIRI: ($) => {
 296       const components = parseReference($);
 297
 298       // The path will always be present (although perhaps empty) on a
 299       // successful parse. If it isn’t (and parsing failed), treat the
 300       // entire input as the path.
 301       components.path ??= `${$}`;
 302
 303       // Escape disallowed codepoints in each component and compose an
 304       // I·R·I from the result.
 305       const reference = objectCreate(null);
 306       for (const componentName in components) {
 307         const componentValue = components[componentName];
 308         reference[componentName] = componentValue == null
 309           ? undefined
 310           : join(
 311             objectCreate(
 312               iriGeneratorIterablePrototype,
 313               {
 314                 generator: {
 315                   value: function* () {
 316                     const encoder = new TE();
 317                     for (
 318                       const character of objectCreate(
 319                         iriCharacterIterablePrototype,
 320                         { source: { value: componentValue } },
 321                       )
 322                     ) {
 323                       if (
 324                         new Matcher(
 325                           `${leiri·ucschar}|${leiri·iprivate}`,
 326                         )(character) &&
 327                         !new Matcher(
 328                           `${ucschar}${
 329                             componentName == "query"
 330                               ? `|${iprivate}`
 331                               : ""
 332                           }`,
 333                         )(character)
 334                       ) {
 335                         // This codepoint needs to be escaped.
 336                         const encoded = call(teEncode, encoder, [
 337                           character,
 338                         ]);
 339                         for (
 340                           let index = 0;
 341                           index < encoded.length;
 342                           ++index
 343                         ) {
 344                           const byte = encoded[index];
 345                           yield `%${byte < 0x10 ? "0" : ""}${
 346                             asciiUppercase(
 347                               call(numberToString, byte, [0x10]),
 348                             )
 349                           }`;
 350                         }
 351                       } else {
 352                         // This codepoint does not need escaping.
 353                         yield character;
 354                       }
 355                     }
 356                   },
 357                 },
 358               },
 359             ),
 360             "",
 361           );
 362       }
 363       return composeReference(reference);
 364     },
 365     escapeForURI: ($) =>
 366       join(
 367         objectCreate(
 368           iriGeneratorIterablePrototype,
 369           {
 370             generator: {
 371               value: function* () {
 372                 const encoder = new TE();
 373                 for (
 374                   const character of objectCreate(
 375                     iriCharacterIterablePrototype,
 376                     { source: { value: `${$}` } },
 377                   )
 378                 ) {
 379                   if (
 380                     new Matcher(
 381                       `${leiri·ucschar}|${leiri·iprivate}`,
 382                     )(character)
 383                   ) {
 384                     // This codepoint needs to be escaped.
 385                     const encoded = call(teEncode, encoder, [
 386                       character,
 387                     ]);
 388                     for (
 389                       let index = 0;
 390                       index < encoded.length;
 391                       ++index
 392                     ) {
 393                       const byte = encoded[index];
 394                       yield `%${byte < 0x10 ? "0" : ""}${
 395                         asciiUppercase(
 396                           call(numberToString, byte, [0x10]),
 397                         )
 398                       }`;
 399                     }
 400                   } else {
 401                     // This codepoint does not need escaping.
 402                     yield character;
 403                   }
 404                 }
 405               },
 406             },
 407           },
 408         ),
 409         "",
 410       ),
 411     removeDotSegments: ($) => {
 412       const input = `${$}`;
 413       const output = [];
 414       const { length } = input;
 415       let index = 0;
 416       while (index < length) {
 417         if (stringStartsWith(input, "../", index)) {
 418           // The input starts with a double leader; drop it. This can
 419           // only occur at the beginning of the input.
 420           index += 3;
 421         } else if (stringStartsWith(input, "./", index)) {
 422           // The input starts with a single leader; drop it. This can
 423           // only occur at the beginning of the input.
 424           index += 2;
 425         } else if (stringStartsWith(input, "/./", index)) {
 426           // The input starts with a slash, single leader, and another
 427           // slash. Ignore it, and move the input to just before the
 428           // second slash.
 429           index += 2;
 430         } else if (
 431           stringStartsWith(input, "/.", index) && index + 2 == length
 432         ) {
 433           // The input starts with a slash and single leader, and this
 434           // exhausts the string. Push an empty segment and move the
 435           // index to the end of the string.
 436           push(output, "/");
 437           index = length;
 438         } else if (stringStartsWith(input, "/../", index)) {
 439           // The input starts with a slash, double leader, and another
 440           // slash. Drop a segment from the output, and move the input
 441           // to just before the second slash.
 442           index += 3;
 443           splice(output, -1, 1);
 444         } else if (
 445           stringStartsWith(input, "/..", index) && index + 3 == length
 446         ) {
 447           // The input starts with a slash and single leader, and this
 448           // exhausts the string. Drop a segment from the output, push
 449           // an empty segment, and move the index to the end of the
 450           // string.
 451           splice(output, -1, 1, "/");
 452           index = length;
 453         } else if (
 454           stringStartsWith(input, ".", index) && index + 1 == length ||
 455           stringStartsWith(input, "..", index) && index + 2 == length
 456         ) {
 457           // The input starts with a single or double leader, and this
 458           // exhausts the string. Do nothing (this can only occur at
 459           // the beginning of input) and move the index to the end of
 460           // the string.
 461           index = length;
 462         } else {
 463           // The input does not start with a leader. Advance the index
 464           // to the position before the next slash and push the segment
 465           // between the old and new positions.
 466           const nextIndex = getFirstSubstringIndex(
 467             input,
 468             "/",
 469             index + 1,
 470           );
 471           if (nextIndex == -1) {
 472             // No slash remains; set index to the end of the string.
 473             push(output, substring(input, index));
 474             index = length;
 475           } else {
 476             // There are further path segments.
 477             push(output, substring(input, index, nextIndex));
 478             index = nextIndex;
 479           }
 480         }
 481       }
 482       return join(
 483         objectCreate(
 484           iriSegmentIterablePrototype,
 485           { segments: { value: output } },
 486         ),
 487         "",
 488       );
 489     },
 490   };
 491 })();
 492
 493 export const {
 494   isAbsoluteIRI, // I·R·I with no fragment
 495   isAbsoluteLEIRI, // L·E·I·R·I with no fragment
 496   isAbsoluteURI, // U·R·I with no fragment
 497   isIRI,
 498   isIRIPath,
 499   isIRIReference,
 500   isIRISuffix, // only authority, path, query, fragment
 501   isLEIRI,
 502   isLEIRIPath,
 503   isLEIRIReference,
 504   isLEIRISuffix, // only authority, path, query, fragment
 505   isURI,
 506   isURIPath,
 507   isURIReference,
 508   isURISuffix, // only authority, path, query, fragment
 509 } = Object.fromEntries(
 510   Object.entries({
 511     isAbsoluteIRI: absolute·IRI,
 512     isAbsoluteLEIRI: absolute·LEIRI,
 513     isAbsoluteURI: absolute·URI,
 514     isIRI: IRI,
 515     isIRIPath: ipath,
 516     isIRIReference: IRI·reference,
 517     isIRISuffix:
 518       rawString`(?:${iauthority})(?:${ipath·abempty})(?:\?(?:${iquery}))?(?:#(?:${ifragment}))?`,
 519     isLEIRI: LEIRI,
 520     isLEIRIPath: leiri·ipath,
 521     isLEIRIReference: LEIRI·reference,
 522     isLEIRISuffix:
 523       rawString`(?:${leiri·iauthority})(?:${leiri·ipath·abempty})(?:\?(?:${leiri·iquery}))?(?:#(?:${leiri·ifragment}))?`,
 524     isURI: URI,
 525     isURIPath: path,
 526     isURIReference: URI·reference,
 527     isURISuffix:
 528       rawString`(?:${authority})(?:${path·abempty})(?:\?(?:${query}))?(?:#(?:${fragment}))?`,
 529   }).map(
 530     ([key, value]) => [key, new Matcher(rawString`^(?:${value})$`)],
 531   ),
 532 );
 533
 534 /**
 535  * Returns the result of merging the provided reference path with the
 536  * provided base path.
 537  *
 538  * See §5.2.3 of R·F·C 3986.
 539  */
 540 export const mergePaths = (base, reference) => {
 541   const baseStr = `${base}` || "/";
 542   return `${
 543     substring(baseStr, 0, getLastSubstringIndex(baseStr, "/") + 1)
 544   }${reference}`;
 545 };
 546
 547 export const {
 548   /**
 549    * Returns the `scheme`, `authority`, `path`, `query`, and `fragment`
 550    * of the provided (L·E·)I·R·I reference.
 551    *
 552    * `path` will always be defined for valid references, and will be
 553    * undefined for values which are not valid L·E·I·R·Is.
 554    */
 555   parseReference,
 556 } = (() => {
 557   const RE = RegExp;
 558   const { prototype: rePrototype } = RE;
 559   const { exec: reExec } = rePrototype;
 560   return {
 561     parseReference: ($) => {
 562       const re = new RE(
 563         rawString`^(?:(?<absolute·scheme>${scheme}):(?://(?<absolute·authority>${leiri·iauthority})(?<absolute·patha>${leiri·ipath·abempty})|(?<absolute·pathb>(?:${leiri·ipath·absolute})|(?:${leiri·ipath·rootless})|(?:${leiri·ipath·empty})))(?:\?(?<absolute·query>${leiri·iquery}))?(?:#(?<absolute·fragment>${leiri·ifragment}))?|(?://(?<relative·authority>${leiri·iauthority})(?<relative·patha>${leiri·ipath·abempty})|(?<relative·pathb>(?:${leiri·ipath·absolute})|(?:${leiri·ipath·noscheme})|(?:${leiri·ipath·empty})))(?:\?(?<relative·query>${leiri·iquery}))?(?:#(?<relative·fragment>${leiri·ifragment}))?)$`,
 564         "u",
 565       );
 566       const {
 567         absolute·scheme,
 568         absolute·authority,
 569         absolute·patha,
 570         absolute·pathb,
 571         absolute·query,
 572         absolute·fragment,
 573         relative·authority,
 574         relative·patha,
 575         relative·pathb,
 576         relative·query,
 577         relative·fragment,
 578       } = call(reExec, re, [$])?.groups ?? {};
 579       return {
 580         scheme: absolute·scheme,
 581         authority: absolute·authority ?? relative·authority,
 582         path: absolute·patha ?? absolute·pathb ?? relative·patha ??
 583           relative·pathb,
 584         query: absolute·query ?? relative·query,
 585         fragment: absolute·fragment ?? relative·fragment,
 586       };
 587     },
 588   };
 589 })();
 590
 591 /**
 592  * Resolves the provided reference relative to the provided base
 593  * (L·E·)I·R·I.
 594  *
 595  * See §5.2 of R·F·C 3986.
 596  */
 597 export const resolveReference = (R, Base = location ?? "") => {
 598   const {
 599     scheme: Base·scheme,
 600     authority: Base·authority,
 601     path: Base·path,
 602     query: Base·query,
 603   } = parseReference(Base);
 604   if (Base·scheme == null) {
 605     // Base I·R·I’s must be valid I·R·I’s, meaning they must have a
 606     // scheme.
 607     throw new TypeError(
 608       `Piscēs: Base did not have a scheme: ${Base}.`,
 609     );
 610   } else {
 611     // The provided Base I·R·I is valid.
 612     const {
 613       scheme: R·scheme,
 614       authority: R·authority,
 615       path: R·path,
 616       query: R·query,
 617       fragment: R·fragment,
 618     } = parseReference(R);
 619     return composeReference(
 620       R·scheme != null
 621         ? {
 622           scheme: R·scheme,
 623           authority: R·authority,
 624           path: removeDotSegments(R·path),
 625           query: R·query,
 626           fragment: R·fragment,
 627         }
 628         : R·authority != null
 629         ? {
 630           scheme: Base·scheme,
 631           authority: R·authority,
 632           path: removeDotSegments(R·path),
 633           query: R·query,
 634           fragment: R·fragment,
 635         }
 636         : !R·path
 637         ? {
 638           scheme: Base·scheme,
 639           authority: Base·authority,
 640           path: Base·path,
 641           query: R·query ?? Base·query,
 642           fragment: R·fragment,
 643         }
 644         : {
 645           scheme: Base·scheme,
 646           authority: Base·authority,
 647           path: R·path[0] == "/"
 648             ? removeDotSegments(R·path)
 649             : removeDotSegments(mergePaths(Base·path, R·path)),
 650           query: R·query,
 651           fragment: R·fragment,
 652         },
 653     );
 654   }
 655 };