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
// @ts-check
'use strict';
const { assert } = require('chai');
const PrismLoader = require('./helper/prism-loader');
const TestDiscovery = require('./helper/test-discovery');
const TestCase = require('./helper/test-case');
const { BFS, BFSPathToPrismTokenPath, parseRegex } = require('./helper/util');
const { languages } = require('../components.json');
const { visitRegExpAST } = require('regexpp');
const { transform, combineTransformers, getIntersectionWordSets, JS, Words, NFA, Transformers } = require('refa');
const scslre = require('scslre');
const { argv } = require('yargs');
const RAA = require('regexp-ast-analysis');
/**
* A map from language id to a list of code snippets in that language.
*
* @type {Map<string, string[]>}
*/
const testSnippets = new Map();
const testSuite = TestDiscovery.loadAllTests();
for (const [languageIdentifier, files] of testSuite) {
const lang = TestCase.parseLanguageNames(languageIdentifier).mainLanguage;
let snippets = testSnippets.get(lang);
if (snippets === undefined) {
snippets = [];
testSnippets.set(lang, snippets);
}
for (const file of files) {
snippets.push(TestCase.TestCaseFile.readFromFile(file).code);
}
}
for (const lang in languages) {
if (lang === 'meta' || (!!argv.language && lang !== argv.language)) {
continue;
}
describe(`Patterns of '${lang}'`, function () {
const Prism = PrismLoader.createInstance(lang);
testPatterns(Prism, lang);
});
let optional = toArray(languages[lang].optional);
let modify = toArray(languages[lang].modify);
if (optional.length > 0 || modify.length > 0) {
let name = `Patterns of '${lang}'`;
if (optional.length > 0) {
name += ` + optional dependencies '${optional.join("', '")}'`;
}
if (modify.length > 0) {
name += ` + modify dependencies '${modify.join("', '")}'`;
}
describe(name, function () {
const Prism = PrismLoader.createInstance([...optional, ...modify, lang]);
testPatterns(Prism, lang);
});
}
}
/**
* Tests all patterns in the given Prism instance.
*
* @param {any} Prism
* @param {string} mainLanguage
*
* @typedef {import("./helper/util").LiteralAST} LiteralAST
* @typedef {import("regexpp/ast").CapturingGroup} CapturingGroup
* @typedef {import("regexpp/ast").Element} Element
* @typedef {import("regexpp/ast").Group} Group
* @typedef {import("regexpp/ast").LookaroundAssertion} LookaroundAssertion
* @typedef {import("regexpp/ast").Pattern} Pattern
*/
function testPatterns(Prism, mainLanguage) {
/**
* Returns a list of relevant languages in the Prism instance.
*
* The list does not included readonly dependencies and aliases.
*
* @returns {string[]}
*/
function getRelevantLanguages() {
return [mainLanguage, ...toArray(languages[mainLanguage].modify)]
.filter(lang => lang in Prism.languages);
}
/**
* Invokes the given function on every pattern in `Prism.languages`.
*
* _Note:_ This will aggregate all errors thrown by the given callback and throw an aggregated error at the end
* of the iteration. You can also append any number of errors per callback using the `reportError` function.
*
* @param {(values: ForEachPatternCallbackValue) => void} callback
*
* @typedef ForEachPatternCallbackValue
* @property {RegExp} pattern
* @property {LiteralAST} ast
* @property {string} tokenPath
* @property {string} name
* @property {any} parent
* @property {boolean} lookbehind Whether the first capturing group of the pattern is a Prism lookbehind group.
* @property {CapturingGroup | undefined} lookbehindGroup
* @property {{ key: string, value: any }[]} path
* @property {(message: string) => void} reportError
*/
function forEachPattern(callback) {
const visited = new Set();
const errors = [];
/**
* @param {object} root
* @param {string} rootStr
*/
function traverse(root, rootStr) {
if (visited.has(root)) {
return;
}
visited.add(root);
BFS(root, path => {
const { key, value } = path[path.length - 1];
const tokenPath = BFSPathToPrismTokenPath(path, rootStr);
visited.add(value);
if (Object.prototype.toString.call(value) == '[object RegExp]') {
try {
let ast;
try {
ast = parseRegex(value);
} catch (error) {
throw new SyntaxError(`Invalid RegExp at ${tokenPath}\n\n${error.message}`);
}
const parent = path.length > 1 ? path[path.length - 2].value : undefined;
const lookbehind = key === 'pattern' && parent && !!parent.lookbehind;
const lookbehindGroup = lookbehind ? getFirstCapturingGroup(ast.pattern) : undefined;
callback({
pattern: value,
ast,
tokenPath,
name: key,
parent,
path,
lookbehind,
lookbehindGroup,
reportError: message => errors.push(message)
});
} catch (error) {
errors.push(error);
}
}
});
}
// static analysis
traverse(Prism.languages, 'Prism.languages');
// dynamic analysis
for (const lang of getRelevantLanguages()) {
const snippets = testSnippets.get(lang);
const grammar = Prism.languages[lang];
const oldTokenize = Prism.tokenize;
Prism.tokenize = function (_, grammar) {
const result = oldTokenize.apply(this, arguments);
traverse(grammar, lang + ': <Unknown>');
return result;
};
for (const snippet of (snippets || [])) {
Prism.highlight(snippet, grammar, lang);
}
Prism.tokenize = oldTokenize;
}
if (errors.length > 0) {
throw new Error(errors.map(e => String(e.message || e)).join('\n\n'));
}
}
/**
* Invokes the given callback for all capturing groups in the given pattern in left to right order.
*
* @param {Pattern} pattern
* @param {(values: ForEachCapturingGroupCallbackValue) => void} callback
*
* @typedef ForEachCapturingGroupCallbackValue
* @property {CapturingGroup} group
* @property {number} number Note: Starts at 1.
*/
function forEachCapturingGroup(pattern, callback) {
let number = 0;
visitRegExpAST(pattern, {
onCapturingGroupEnter(node) {
callback({
group: node,
number: ++number
});
}
});
}
it('- should not match the empty string', function () {
forEachPattern(({ ast, pattern, tokenPath }) => {
// test for empty string
const empty = RAA.isPotentiallyZeroLength(ast.pattern.alternatives);
assert.isFalse(empty, `${tokenPath}: ${pattern} should not match the empty string.\n\n`
+ `Patterns that do match the empty string can potentially cause infinitely many empty tokens. `
+ `Make sure that all patterns always consume at least one character.`);
});
});
it('- should have a capturing group if lookbehind is set to true', function () {
forEachPattern(({ ast, tokenPath, lookbehind }) => {
if (lookbehind) {
let hasCapturingGroup = false;
forEachCapturingGroup(ast.pattern, () => { hasCapturingGroup = true; });
if (!hasCapturingGroup) {
assert.fail(`${tokenPath}: The pattern is set to 'lookbehind: true' but does not have a capturing group.\n\n`
+ `Prism lookbehind groups use the captured text of the first capturing group to simulate a lookbehind. `
+ `Without a capturing group, a lookbehind is not possible.\n`
+ `To fix this, either add a capturing group for the lookbehind or remove the 'lookbehind' property.`);
}
}
});
});
it('- should not have lookbehind groups that can be preceded by other some characters', function () {
forEachPattern(({ tokenPath, lookbehindGroup }) => {
if (lookbehindGroup && !isFirstMatch(lookbehindGroup)) {
assert.fail(`${tokenPath}: The lookbehind group ${lookbehindGroup.raw} might be preceded by some characters.\n\n`
+ `Prism assumes that the lookbehind group, if captured, is the first thing matched by the regex. `
+ `If characters might precede the lookbehind group (e.g. /a?(b)c/), then Prism cannot correctly apply the lookbehind correctly in all cases.\n`
+ `To fix this, either remove the preceding characters or include them in the lookbehind group.`);
}
});
});
it('- should not have lookbehind groups that only have zero-width alternatives', function () {
forEachPattern(({ tokenPath, lookbehindGroup, reportError }) => {
if (lookbehindGroup && RAA.isZeroLength(lookbehindGroup)) {
const groupContent = lookbehindGroup.raw.substr(1, lookbehindGroup.raw.length - 2);
const replacement = lookbehindGroup.alternatives.length === 1 ? groupContent : `(?:${groupContent})`;
reportError(`${tokenPath}: The lookbehind group ${lookbehindGroup.raw} does not consume characters.\n\n`
+ `Therefor it is not necessary to use a lookbehind group.\n`
+ `To fix this, replace the lookbehind group with ${replacement} and remove the 'lookbehind' property.`);
}
});
});
it('- should not have unused capturing groups', function () {
forEachPattern(({ ast, tokenPath, lookbehindGroup, reportError }) => {
forEachCapturingGroup(ast.pattern, ({ group, number }) => {
const isLookbehindGroup = group === lookbehindGroup;
if (group.references.length === 0 && !isLookbehindGroup) {
const fixes = [];
fixes.push(`Make this group a non-capturing group ('(?:...)' instead of '(...)'). (It's usually this option.)`);
fixes.push(`Reference this group with a backreference (use '\\${number}' for this).`);
if (number === 1 && !lookbehindGroup) {
if (isFirstMatch(group)) {
fixes.push(`Add a 'lookbehind: true' declaration.`);
} else {
fixes.push(`Add a 'lookbehind: true' declaration. (This group is not a valid lookbehind group because it can be preceded by some characters.)`);
}
}
reportError(`${tokenPath}: Unused capturing group ${group.raw}.\n\n`
+ `Unused capturing groups generally degrade the performance of regular expressions. `
+ `They might also be a sign that a backreference is incorrect or that a 'lookbehind: true' declaration in missing.\n`
+ `To fix this, do one of the following:\n`
+ fixes.map(f => '- ' + f).join('\n'));
}
});
});
});
it('- should have nice names and aliases', function () {
const niceName = /^[a-z][a-z\d]*(?:-[a-z\d]+)*$/;
function testName(name, desc = 'token name') {
if (!niceName.test(name)) {
assert.fail(`The ${desc} '${name}' does not match ${niceName}.\n\n`
+ `To fix this, choose a name that matches the above regular expression.`);
}
}
forEachPattern(({ name, parent, tokenPath, path }) => {
// token name
let offset = 1;
if (name == 'pattern') { // regex can be inside an object
offset++;
}
if (Array.isArray(path[path.length - 1 - offset].value)) { // regex/regex object can be inside an array
offset++;
}
const patternName = path[path.length - offset].key;
testName(patternName);
// check alias
if (name == 'pattern' && 'alias' in parent) {
const alias = parent.alias;
if (typeof alias === 'string') {
testName(alias, `alias of '${tokenPath}'`);
} else if (Array.isArray(alias)) {
alias.forEach(name => testName(name, `alias of '${tokenPath}'`));
}
}
});
});
it('- should not use octal escapes', function () {
forEachPattern(({ ast, tokenPath, reportError }) => {
visitRegExpAST(ast.pattern, {
onCharacterEnter(node) {
if (/^\\(?:[1-9]|\d{2,})$/.test(node.raw)) {
reportError(`${tokenPath}: Octal escape ${node.raw}.\n\n`
+ `Octal escapes can be confused with backreferences, so please do not use them.\n`
+ `To fix this, use a different escape method. `
+ `Note that this could also be an invalid backreference, so be sure to carefully analyse the pattern.`);
}
}
});
});
});
it('- should not cause exponential backtracking', function () {
replaceRegExpProto(exec => {
return function (input) {
checkExponentialBacktracking('<Unknown>', this);
return exec.call(this, input);
};
}, () => {
forEachPattern(({ pattern, ast, tokenPath }) => {
checkExponentialBacktracking(tokenPath, pattern, ast);
});
});
});
it('- should not cause polynomial backtracking', function () {
replaceRegExpProto(exec => {
return function (input) {
checkPolynomialBacktracking('<Unknown>', this);
return exec.call(this, input);
};
}, () => {
forEachPattern(({ pattern, ast, tokenPath }) => {
checkPolynomialBacktracking(tokenPath, pattern, ast);
});
});
});
}
/**
* Returns the first capturing group in the given pattern.
*
* @param {Pattern} pattern
* @returns {CapturingGroup | undefined}
*/
function getFirstCapturingGroup(pattern) {
let cap = undefined;
try {
visitRegExpAST(pattern, {
onCapturingGroupEnter(node) {
cap = node;
throw new Error('stop');
}
});
} catch (error) {
// ignore errors
}
return cap;
}
/**
* Returns whether the given element will always at the start of the whole match.
*
* @param {Element} element
* @returns {boolean}
*/
function isFirstMatch(element) {
const parent = element.parent;
switch (parent.type) {
case 'Alternative': {
// all elements before this element have to of zero length
if (!parent.elements.slice(0, parent.elements.indexOf(element)).every(RAA.isZeroLength)) {
return false;
}
const grandParent = parent.parent;
if (grandParent.type === 'Pattern') {
return true;
} else {
return isFirstMatch(grandParent);
}
}
case 'Quantifier':
if (parent.max >= 2) {
return false;
} else {
return isFirstMatch(parent);
}
default:
throw new Error(`Internal error: The given node should not be a '${element.type}'.`);
}
}
/**
* Returns whether the given node either is or is a child of what is effectively a Kleene star.
*
* @param {import("regexpp/ast").Node} node
* @returns {boolean}
*/
function underAStar(node) {
return RAA.getEffectiveMaximumRepetition(node) > 10;
}
/**
* @param {Iterable<T>} iter
* @returns {T | undefined}
* @template T
*/
function firstOf(iter) {
const [first] = iter;
return first;
}
/**
* A set of all safe (non-exponentially backtracking) RegExp literals (string).
*
* @type {Set<string | RegExp>}
*/
const expoSafeRegexes = new Set();
/** @type {Transformers.CreationOptions} */
const options = {
ignoreOrder: true,
ignoreAmbiguity: true
};
const transformer = combineTransformers([
Transformers.inline(options),
Transformers.removeDeadBranches(options),
Transformers.unionCharacters(options),
Transformers.moveUpEmpty(options),
Transformers.nestedQuantifiers(options),
Transformers.sortAssertions(options),
Transformers.removeUnnecessaryAssertions(options),
Transformers.applyAssertions(options),
]);
/**
* @param {string} path
* @param {RegExp} pattern
* @param {LiteralAST} [ast]
* @returns {void}
*/
function checkExponentialBacktracking(path, pattern, ast) {
if (expoSafeRegexes.has(pattern)) {
// we know that the pattern won't cause exp backtracking because we checked before
return;
}
const patternStr = String(pattern);
if (expoSafeRegexes.has(patternStr)) {
// we know that the pattern won't cause exp backtracking because we checked before
return;
}
if (!ast) {
ast = parseRegex(pattern);
}
const parser = JS.Parser.fromAst(ast);
/**
* Parses the given element and creates its NFA.
*
* @param {import("refa").JS.ParsableElement} element
* @returns {NFA}
*/
function toNFA(element) {
let { expression, maxCharacter } = parser.parseElement(element, {
maxBackreferenceWords: 1000,
backreferences: 'disable'
});
return NFA.fromRegex(transform(transformer, expression), { maxCharacter }, { assertions: 'disable' });
}
/**
* Checks whether the alternatives of the given node are disjoint. If the alternatives are not disjoint
* and the give node is a descendant of an effective Kleene star, then an error will be thrown.
*
* @param {CapturingGroup | Group | LookaroundAssertion} node
* @returns {void}
*/
function checkDisjointAlternatives(node) {
if (!underAStar(node) || node.alternatives.length < 2) {
return;
}
const alternatives = node.alternatives;
const total = toNFA(alternatives[0]);
total.withoutEmptyWord();
for (let i = 1, l = alternatives.length; i < l; i++) {
const a = alternatives[i];
const current = toNFA(a);
current.withoutEmptyWord();
if (!total.isDisjointWith(current)) {
assert.fail(`${path}: The alternative \`${a.raw}\` is not disjoint with at least one previous alternative.`
+ ` This will cause exponential backtracking.`
+ `\n\nTo fix this issue, you have to rewrite the ${node.type} \`${node.raw}\`.`
+ ` The goal is that all of its alternatives are disjoint.`
+ ` This means that if a (sub-)string is matched by the ${node.type}, then only one of its alternatives can match the (sub-)string.`
+ `\n\nExample: \`(?:[ab]|\\w|::)+\``
+ `\nThe alternatives of the group are not disjoint because the string "a" can be matched by both \`[ab]\` and \`\\w\`.`
+ ` In this example, the pattern can easily be fixed because the \`[ab]\` is a subset of the \`\\w\`, so its enough to remove the \`[ab]\` alternative to get \`(?:\\w|::)+\` as the fixed pattern.`
+ `\nIn the real world, patterns can be a lot harder to fix.`
+ ` If you are trying to make the tests pass for a pull request but can\'t fix the issue yourself, then make the pull request (or commit) anyway.`
+ ` A maintainer will help you.`
+ `\n\nFull pattern:\n${pattern}`);
} else if (i !== l - 1) {
total.union(current);
}
}
}
visitRegExpAST(ast.pattern, {
onCapturingGroupLeave: checkDisjointAlternatives,
onGroupLeave: checkDisjointAlternatives,
onAssertionLeave(node) {
if (node.kind === 'lookahead' || node.kind === 'lookbehind') {
checkDisjointAlternatives(node);
}
},
onQuantifierLeave(node) {
if (node.max < 10) {
return; // not a star
}
if (node.element.type !== 'CapturingGroup' && node.element.type !== 'Group') {
return; // not a group
}
// The idea here is the following:
//
// We have found a part `A*` of the regex (`A` is assumed to not accept the empty word). Let `I` be
// the intersection of `A` and `A{2,}`. If `I` is not empty, then there exists a non-empty word `w`
// that is accepted by both `A` and `A{2,}`. That means that there exists some `m>1` for which `w`
// is accepted by `A{m}`.
// This means that there are at least two ways `A*` can accept `w`. It can be accepted as `A` or as
// `A{m}`. Hence there are at least 2^n ways for `A*` to accept the word `w{n}`. This is the main
// requirement for exponential backtracking.
//
// This is actually only a crude approximation for the real analysis that would have to be done. We
// would actually have to check the intersection `A{p}` and `A{p+1,}` for all p>0. However, in most
// cases, the approximation is good enough.
const nfa = toNFA(node.element);
nfa.withoutEmptyWord();
const twoStar = nfa.copy();
twoStar.quantify(2, Infinity);
if (!nfa.isDisjointWith(twoStar)) {
const word = Words.pickMostReadableWord(firstOf(getIntersectionWordSets(nfa, twoStar)));
const example = Words.fromUnicodeToString(word);
assert.fail(`${path}: The quantifier \`${node.raw}\` ambiguous for all words ${JSON.stringify(example)}.repeat(n) for any n>1.`
+ ` This will cause exponential backtracking.`
+ `\n\nTo fix this issue, you have to rewrite the element (let's call it E) of the quantifier.`
+ ` The goal is modify E such that it is disjoint with repetitions of itself.`
+ ` This means that if a (sub-)string is matched by E, then it must not be possible for E{2}, E{3}, E{4}, etc. to match that (sub-)string.`
+ `\n\nExample 1: \`(?:\\w+|::)+\``
+ `\nThe problem lies in \`\\w+\` because \`\\w+\` and \`(?:\\w+){2}\` are not disjoint as the string "aa" is fully matched by both.`
+ ` In this example, the pattern can easily be fixed by changing \`\\w+\` to \`\\w\`.`
+ `\nExample 2: \`(?:\\w|Foo)+\``
+ `\nThe problem lies in \`\\w\` and \`Foo\` because the string "Foo" can be matched as either repeating \`\\w\` 3 times or by using the \`Foo\` alternative once.`
+ ` In this example, the pattern can easily be fixed because the \`Foo\` alternative is redundant can can be removed.`
+ `\nExample 3: \`(?:\\.\\w+(?:<.*?>)?)+\``
+ `\nThe problem lies in \`<.*?>\`. The string ".a<>.a<>" can be matched as either \`\\. \\w < . . . . >\` or \`\\. \\w < > \\. \\w < >\`.`
+ ` When it comes to exponential backtracking, it doesn't matter whether a quantifier is greedy or lazy.`
+ ` This means that the lazy \`.*?\` can jump over \`>\`.`
+ ` In this example, the pattern can easily be fixed because we just have to prevent \`.*?\` jumping over \`>\`.`
+ ` This can done by replacing \`<.*?>\` with \`<[^\\r\\n>]*>\`.`
+ `\n\nIn the real world, patterns can be a lot harder to fix.`
+ ` If you are trying to make this test pass for a pull request but can\'t fix the issue yourself, then make the pull request (or commit) anyway, a maintainer will help you.`
+ `\n\nFull pattern:\n${pattern}`);
}
},
});
expoSafeRegexes.add(pattern);
expoSafeRegexes.add(patternStr);
}
/**
* A set of all safe (non-polynomially backtracking) RegExp literals (string).
*
* @type {Set<string | RegExp>}
*/
const polySafeRegexes = new Set();
/**
* @param {string} path
* @param {RegExp} pattern
* @param {LiteralAST} [ast]
* @returns {void}
*/
function checkPolynomialBacktracking(path, pattern, ast) {
if (polySafeRegexes.has(pattern)) {
// we know that the pattern won't cause poly backtracking because we checked before
return;
}
const patternStr = String(pattern);
if (polySafeRegexes.has(patternStr)) {
// we know that the pattern won't cause poly backtracking because we checked before
return;
}
if (!ast) {
ast = parseRegex(pattern);
}
const result = scslre.analyse(ast, { maxReports: 1, reportTypes: { 'Move': false } });
if (result.reports.length > 0) {
const report = result.reports[0];
let rangeOffset;
let rangeStr;
let rangeHighlight;
switch (report.type) {
case 'Trade': {
const start = Math.min(report.startQuant.start, report.endQuant.start);
const end = Math.max(report.startQuant.end, report.endQuant.end);
rangeOffset = start + 1;
rangeStr = patternStr.substring(start + 1, end + 1);
rangeHighlight = highlight([
{ ...report.startQuant, label: 'start' },
{ ...report.endQuant, label: 'end' }
], -start);
break;
}
case 'Self': {
rangeOffset = report.parentQuant.start + 1;
rangeStr = patternStr.substring(report.parentQuant.start + 1, report.parentQuant.end + 1);
rangeHighlight = highlight([{ ...report.quant, label: 'self' }], -report.parentQuant.start);
break;
}
case 'Move': {
rangeOffset = 1;
rangeStr = patternStr.substring(1, report.quant.end + 1);
rangeHighlight = highlight([report.quant]);
break;
}
default:
throw new Error('Invalid report type. This should never happen.');
}
const attackChar = `/${report.character.literal.source}/${report.character.literal.flags}`;
const fixed = report.fix();
assert.fail(
`${path}: ${report.exponential ? 'Exponential' : 'Polynomial'} backtracking. `
+ `By repeating any character that matches ${attackChar}, an attack string can be created.`
+ `\n`
+ `\n${indent(rangeStr)}`
+ `\n${indent(rangeHighlight)}`
+ `\n`
+ `\nFull pattern:`
+ `\n${patternStr}`
+ `\n${indent(rangeHighlight, ' '.repeat(rangeOffset))}`
+ `\n`
+ `\n` + (fixed ? `Fixed:\n/${fixed.source}/${fixed.flags}` : `Fix not available.`)
);
}
polySafeRegexes.add(pattern);
polySafeRegexes.add(patternStr);
}
/**
* @param {Highlight[]} highlights
* @param {number} [offset]
* @returns {string}
*
* @typedef Highlight
* @property {number} start
* @property {number} end
* @property {string} [label]
*/
function highlight(highlights, offset = 0) {
highlights.sort((a, b) => a.start - b.start);
const lines = [];
while (highlights.length > 0) {
const newHighlights = [];
let l = '';
for (const highlight of highlights) {
const start = highlight.start + offset;
const end = highlight.end + offset;
if (start < l.length) {
newHighlights.push(highlight);
} else {
l += ' '.repeat(start - l.length);
l += '^';
l += '~'.repeat(end - start - 1);
if (highlight.label) {
l += '[' + highlight.label + ']';
}
}
}
lines.push(l);
highlights = newHighlights;
}
return lines.join('\n');
}
/**
* @param {string} str
* @param {string} amount
* @returns {string}
*/
function indent(str, amount = ' ') {
return str.split(/\r?\n/).map(m => m === '' ? '' : amount + m).join('\n');
}
/**
* @param {(exec: RegExp["exec"]) => RegExp["exec"]} execSupplier
* @param {() => void} fn
*/
function replaceRegExpProto(execSupplier, fn) {
const oldExec = RegExp.prototype.exec;
const oldTest = RegExp.prototype.test;
const newExec = execSupplier(oldExec);
RegExp.prototype.exec = newExec;
RegExp.prototype.test = function (input) {
return newExec.call(this, input) !== null;
};
let error;
try {
fn();
} catch (e) {
error = e;
}
RegExp.prototype.exec = oldExec;
RegExp.prototype.test = oldTest;
if (error) {
throw error;
}
}
/**
* @param {undefined | null | T | T[]} value
* @returns {T[]}
* @template T
*/
function toArray(value) {
if (Array.isArray(value)) {
return value;
} else if (value != null) {
return [value];
} else {
return [];
}
}