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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 19:33:14 +0000 |
commit | 36d22d82aa202bb199967e9512281e9a53db42c9 (patch) | |
tree | 105e8c98ddea1c1e4784a60a5a6410fa416be2de /js/src/irregexp/imported/special-case.h | |
parent | Initial commit. (diff) | |
download | firefox-esr-upstream.tar.xz firefox-esr-upstream.zip |
Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'js/src/irregexp/imported/special-case.h')
-rw-r--r-- | js/src/irregexp/imported/special-case.h | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/js/src/irregexp/imported/special-case.h b/js/src/irregexp/imported/special-case.h new file mode 100644 index 0000000000..ea511af5a4 --- /dev/null +++ b/js/src/irregexp/imported/special-case.h @@ -0,0 +1,127 @@ +// Copyright 2019 the V8 project authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +#ifndef V8_REGEXP_SPECIAL_CASE_H_ +#define V8_REGEXP_SPECIAL_CASE_H_ + +#ifdef V8_INTL_SUPPORT +#include "irregexp/RegExpShim.h" + +#include "unicode/uchar.h" +#include "unicode/uniset.h" +#include "unicode/unistr.h" + +namespace v8 { +namespace internal { + +// Sets of Unicode characters that need special handling under "i" mode + +// For non-unicode ignoreCase matches (aka "i", not "iu"), ECMA 262 +// defines slightly different case-folding rules than Unicode. An +// input character should match a pattern character if the result of +// the Canonicalize algorithm is the same for both characters. +// +// Roughly speaking, for "i" regexps, Canonicalize(c) is the same as +// c.toUpperCase(), unless a) c.toUpperCase() is a multi-character +// string, or b) c is non-ASCII, and c.toUpperCase() is ASCII. See +// https://tc39.es/ecma262/#sec-runtime-semantics-canonicalize-ch for +// the precise definition. +// +// While compiling such regular expressions, we need to compute the +// set of characters that should match a given input character. (See +// GetCaseIndependentLetters and CharacterRange::AddCaseEquivalents.) +// For almost all characters, this can be efficiently computed using +// UnicodeSet::closeOver(USET_CASE_INSENSITIVE). These sets represent +// the remaining special cases. +// +// For a character c, the rules are as follows: +// +// 1. If c is in neither IgnoreSet nor SpecialAddSet, then calling +// UnicodeSet::closeOver(USET_CASE_INSENSITIVE) on a UnicodeSet +// containing c will produce the set of characters that should +// match /c/i (or /[c]/i), and only those characters. +// +// 2. If c is in IgnoreSet, then the only character it should match is +// itself. However, closeOver will add additional incorrect +// matches. For example, consider SHARP S: 'ß' (U+00DF) and 'ẞ' +// (U+1E9E). Although closeOver('ß') = "ßẞ", uppercase('ß') is +// "SS". Step 3.e therefore requires that 'ß' canonicalizes to +// itself, and should not match 'ẞ'. In these cases, we can skip +// the closeOver entirely, because it will never add an equivalent +// character. +// +// 3. If c is in SpecialAddSet, then it should match at least one +// character other than itself. However, closeOver will add at +// least one additional incorrect match. For example, consider the +// letter 'k'. Closing over 'k' gives "kKK" (lowercase k, uppercase +// K, U+212A KELVIN SIGN). However, because of step 3.g, KELVIN +// SIGN should not match either of the other two characters. As a +// result, "k" and "K" are in SpecialAddSet (and KELVIN SIGN is in +// IgnoreSet). To find the correct matches for characters in +// SpecialAddSet, we closeOver the original character, but filter +// out the results that do not have the same canonical value. +// +// The contents of these sets are calculated at build time by +// src/regexp/gen-regexp-special-case.cc, which generates +// gen/src/regexp/special-case.cc. This is done by iterating over the +// result of closeOver for each BMP character, and finding sets for +// which at least one character has a different canonical value than +// another character. Characters that match no other characters in +// their equivalence class are added to IgnoreSet. Characters that +// match at least one other character are added to SpecialAddSet. +// +// For unicode ignoreCase ("iu" and "iv"), +// UnicodeSet::closeOver(USET_CASE_INSENSITIVE) adds all characters that are in +// the same equivalence class. This includes characaters that are in the same +// equivalence class using full case folding. According to the spec, only +// simple case folding shall be considered. We therefore create +// UnicodeNonSimpleCloseOverSet containing all characters for which +// UnicodeSet::closeOver adds characters that are not simple case folds. This +// set should be used similar to IgnoreSet described above. + +class RegExpCaseFolding final : public AllStatic { + public: + static const icu::UnicodeSet& IgnoreSet(); + static const icu::UnicodeSet& SpecialAddSet(); + static const icu::UnicodeSet& UnicodeNonSimpleCloseOverSet(); + + // This implements ECMAScript 2020 21.2.2.8.2 (Runtime Semantics: + // Canonicalize) step 3, which is used to determine whether + // characters match when ignoreCase is true and unicode is false. + static UChar32 Canonicalize(UChar32 ch) { + // a. Assert: ch is a UTF-16 code unit. + CHECK_LE(ch, 0xffff); + + // b. Let s be the String value consisting of the single code unit ch. + icu::UnicodeString s(ch); + + // c. Let u be the same result produced as if by performing the algorithm + // for String.prototype.toUpperCase using s as the this value. + // d. Assert: Type(u) is String. + icu::UnicodeString& u = s.toUpper(); + + // e. If u does not consist of a single code unit, return ch. + if (u.length() != 1) { + return ch; + } + + // f. Let cu be u's single code unit element. + UChar32 cu = u.char32At(0); + + // g. If the value of ch >= 128 and the value of cu < 128, return ch. + if (ch >= 128 && cu < 128) { + return ch; + } + + // h. Return cu. + return cu; + } +}; + +} // namespace internal +} // namespace v8 + +#endif // V8_INTL_SUPPORT + +#endif // V8_REGEXP_SPECIAL_CASE_H_ |