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Diffstat (limited to 'js/src/new-regexp/special-case.h')
| -rw-r--r-- | js/src/new-regexp/special-case.h | 117 |
1 files changed, 0 insertions, 117 deletions
diff --git a/js/src/new-regexp/special-case.h b/js/src/new-regexp/special-case.h deleted file mode 100644 index 31dfd7858..000000000 --- a/js/src/new-regexp/special-case.h +++ /dev/null @@ -1,117 +0,0 @@ -// 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 "new-regexp/regexp-shim.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. - -class RegExpCaseFolding final : public AllStatic { - public: - static const icu::UnicodeSet& IgnoreSet(); - static const icu::UnicodeSet& SpecialAddSet(); - - // 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_ |