tor-browser

Unicode.h (16658B)

---

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: set ts=8 sts=2 et sw=2 tw=80:
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef util_Unicode_h
#define util_Unicode_h

#include "mozilla/Casting.h"  // mozilla::AssertedCast

#include "jspubtd.h"

#include "util/UnicodeNonBMP.h"

namespace js {
namespace unicode {

extern const bool js_isidstart[];
extern const bool js_isident[];
extern const bool js_isspace[];

/*
* This namespace contains all the knowledge required to handle Unicode
* characters in JavaScript.
*
* SPACE
*   Every character that is either in the ECMAScript class WhiteSpace
*   (ES2016, § 11.2) or in LineTerminator (ES2016, § 11.3).
*
*   WhiteSpace
*    \u0009, \u000B, \u000C, \u0020, \u00A0 and \uFEFF
*    and every other Unicode character with the General Category "Zs".
*    See <http://www.unicode.org/reports/tr44/#UnicodeData.txt> for more
*    information about General Categories and the UnicodeData.txt file.
*
*   LineTerminator
*    \u000A, \u000D, \u2028, \u2029
*
* UNICODE_ID_START
*   These are all characters with the Unicode property «ID_Start».
*
* UNICODE_ID_CONTINUE_ONLY
*   These are all characters with the Unicode property «ID_Continue» minus all
*   characters with the Unicode property «ID_Start».
*   And additionally <ZWNJ> and <ZWJ>. (ES2016, § 11.6)
*
* UNICODE_ID_CONTINUE
*   These are all characters with the Unicode property «ID_Continue».
*   And additionally <ZWNJ> and <ZWJ>. (ES2016, § 11.6)
*
*   Attention: UNICODE_ID_START is _not_ IdentifierStart, but you could build
*   a matcher for the real IdentifierPart like this:
*
*   if char in ['$', '_']:
*      return True
*   if GetFlag(char) & UNICODE_ID_CONTINUE:
*      return True
*
*/

namespace CharFlag {
const uint8_t SPACE = 1 << 0;
const uint8_t UNICODE_ID_START = 1 << 1;
const uint8_t UNICODE_ID_CONTINUE_ONLY = 1 << 2;
const uint8_t UNICODE_ID_CONTINUE = UNICODE_ID_START + UNICODE_ID_CONTINUE_ONLY;
}  // namespace CharFlag

constexpr char16_t NO_BREAK_SPACE = 0x00A0;
constexpr char16_t MICRO_SIGN = 0x00B5;
constexpr char16_t LATIN_SMALL_LETTER_SHARP_S = 0x00DF;
constexpr char16_t LATIN_SMALL_LETTER_A_WITH_GRAVE = 0x00E0;
constexpr char16_t DIVISION_SIGN = 0x00F7;
constexpr char16_t LATIN_SMALL_LETTER_Y_WITH_DIAERESIS = 0x00FF;
constexpr char16_t LATIN_CAPITAL_LETTER_I_WITH_DOT_ABOVE = 0x0130;
constexpr char16_t COMBINING_DOT_ABOVE = 0x0307;
constexpr char16_t GREEK_CAPITAL_LETTER_SIGMA = 0x03A3;
constexpr char16_t GREEK_SMALL_LETTER_FINAL_SIGMA = 0x03C2;
constexpr char16_t GREEK_SMALL_LETTER_SIGMA = 0x03C3;
constexpr char16_t LINE_SEPARATOR = 0x2028;
constexpr char16_t PARA_SEPARATOR = 0x2029;
constexpr char16_t REPLACEMENT_CHARACTER = 0xFFFD;

const char16_t LeadSurrogateMin = 0xD800;
const char16_t LeadSurrogateMax = 0xDBFF;
const char16_t TrailSurrogateMin = 0xDC00;
const char16_t TrailSurrogateMax = 0xDFFF;

const char32_t UTF16Max = 0xFFFF;
const char32_t NonBMPMin = 0x10000;
const char32_t NonBMPMax = 0x10FFFF;

class CharacterInfo {
 /*
  * upperCase and lowerCase normally store the delta between two
  * letters. For example the lower case alpha (a) has the char code
  * 97, and the upper case alpha (A) has 65. So for "a" we would
  * store -32 in upperCase (97 + (-32) = 65) and 0 in lowerCase,
  * because this char is already in lower case.
  * Well, not -32 exactly, but (2**16 - 32) to induce
  * unsigned overflow with identical mathematical behavior.
  * For upper case alpha, we would store 0 in upperCase and 32 in
  * lowerCase (65 + 32 = 97).
  *
  * We use deltas to reuse information for multiple characters. For
  * example the whole lower case latin alphabet fits into one entry,
  * because it's always a UnicodeLetter and upperCase contains
  * -32.
  */
public:
 uint16_t upperCase;
 uint16_t lowerCase;
 uint8_t flags;

 inline bool isSpace() const { return flags & CharFlag::SPACE; }

 inline bool isUnicodeIDStart() const {
   return flags & CharFlag::UNICODE_ID_START;
 }

 inline bool isUnicodeIDContinue() const {
   // Also matches <ZWNJ> and <ZWJ>!
   return flags & CharFlag::UNICODE_ID_CONTINUE;
 }
};

extern const uint8_t index1[];
extern const uint8_t index2[];
extern const CharacterInfo js_charinfo[];

constexpr size_t CharInfoShift = 6;

inline const CharacterInfo& CharInfo(char16_t code) {
 const size_t shift = CharInfoShift;
 size_t index = index1[code >> shift];
 index = index2[(index << shift) + (code & ((1 << shift) - 1))];

 return js_charinfo[index];
}

inline bool IsIdentifierStart(char16_t ch) {
 /*
  * ES2016 11.6 IdentifierStart
  *  $ (dollar sign)
  *  _ (underscore)
  *  or any character with the Unicode property «ID_Start».
  *
  * We use a lookup table for small and thus common characters for speed.
  */

 if (ch < 128) {
   return js_isidstart[ch];
 }

 return CharInfo(ch).isUnicodeIDStart();
}

inline bool IsIdentifierStartASCII(char ch) {
 MOZ_ASSERT(uint8_t(ch) < 128);
 return js_isidstart[uint8_t(ch)];
}

bool IsIdentifierStartNonBMP(char32_t codePoint);

inline bool IsIdentifierStart(char32_t codePoint) {
 if (MOZ_UNLIKELY(codePoint > UTF16Max)) {
   return IsIdentifierStartNonBMP(codePoint);
 }
 return IsIdentifierStart(char16_t(codePoint));
}

inline bool IsIdentifierPart(char16_t ch) {
 /*
  * ES2016 11.6 IdentifierPart
  *  $ (dollar sign)
  *  _ (underscore)
  *  <ZWNJ>
  *  <ZWJ>
  *  or any character with the Unicode property «ID_Continue».
  *
  * We use a lookup table for small and thus common characters for speed.
  */

 if (ch < 128) {
   return js_isident[ch];
 }

 return CharInfo(ch).isUnicodeIDContinue();
}

inline bool IsIdentifierPartASCII(char ch) {
 MOZ_ASSERT(uint8_t(ch) < 128);
 return js_isident[uint8_t(ch)];
}

bool IsIdentifierPartNonBMP(char32_t codePoint);

inline bool IsIdentifierPart(char32_t codePoint) {
 if (MOZ_UNLIKELY(codePoint > UTF16Max)) {
   return IsIdentifierPartNonBMP(codePoint);
 }
 return IsIdentifierPart(char16_t(codePoint));
}

inline bool IsUnicodeIDStart(char16_t ch) {
 return CharInfo(ch).isUnicodeIDStart();
}

bool IsUnicodeIDStartNonBMP(char32_t codePoint);

inline bool IsUnicodeIDStart(char32_t codePoint) {
 if (MOZ_UNLIKELY(codePoint > UTF16Max)) {
   return IsIdentifierStartNonBMP(codePoint);
 }
 return IsUnicodeIDStart(char16_t(codePoint));
}

// IsSpace checks if a code point is included in the merged set of WhiteSpace
// and LineTerminator specified by #sec-white-space and #sec-line-terminators.
// We combine them because nearly every calling function wants this, excepting
// only some tokenizer code that necessarily handles LineTerminator specially
// due to UTF-8/UTF-16 template specialization.
inline bool IsSpace(char16_t ch) {
 // ASCII code points are very common and must be handled quickly, so use a
 // lookup table for them.
 if (ch < 128) {
   return js_isspace[ch];
 }

 // NO-BREAK SPACE is supposed to be the most common non-ASCII WhiteSpace code
 // point, so inline its handling too.
 if (ch == NO_BREAK_SPACE) {
   return true;
 }

 return CharInfo(ch).isSpace();
}

inline bool IsSpace(JS::Latin1Char ch) {
 if (ch < 128) {
   return js_isspace[ch];
 }

 if (ch == NO_BREAK_SPACE) {
   return true;
 }

 MOZ_ASSERT(!CharInfo(ch).isSpace());
 return false;
}

inline bool IsSpace(char ch) {
 return IsSpace(static_cast<JS::Latin1Char>(ch));
}

// IsSpace(char32_t) must additionally exclude everything non-BMP.
inline bool IsSpace(char32_t ch) {
 if (ch < 128) {
   return js_isspace[ch];
 }

 if (ch == NO_BREAK_SPACE) {
   return true;
 }

 // An assertion in make_unicode.py:make_unicode_file guarantees that there are
 // no Space_Separator (Zs) code points outside the BMP.
 if (ch >= NonBMPMin) {
   return false;
 }

 return CharInfo(mozilla::AssertedCast<char16_t>(ch)).isSpace();
}

/*
* Returns the simple upper case mapping (possibly the identity mapping; see
* ChangesWhenUpperCasedSpecialCasing for details) of the given UTF-16 code
* unit.
*/
inline char16_t ToUpperCase(char16_t ch) {
 if (ch < 128) {
   if (ch >= 'a' && ch <= 'z') {
     return ch - ('a' - 'A');
   }
   return ch;
 }

 const CharacterInfo& info = CharInfo(ch);

 return uint16_t(ch) + info.upperCase;
}

/*
* Returns the simple lower case mapping (possibly the identity mapping; see
* ChangesWhenUpperCasedSpecialCasing for details) of the given UTF-16 code
* unit.
*/
inline char16_t ToLowerCase(char16_t ch) {
 if (ch < 128) {
   if (ch >= 'A' && ch <= 'Z') {
     return ch + ('a' - 'A');
   }
   return ch;
 }

 const CharacterInfo& info = CharInfo(ch);

 return uint16_t(ch) + info.lowerCase;
}

extern const JS::Latin1Char latin1ToLowerCaseTable[];

/*
* Returns the simple lower case mapping (possibly the identity mapping; see
* ChangesWhenUpperCasedSpecialCasing for details) of the given Latin-1 code
* point.
*/
inline JS::Latin1Char ToLowerCase(JS::Latin1Char ch) {
 return latin1ToLowerCaseTable[ch];
}

/*
* Returns the simple lower case mapping (possibly the identity mapping; see
* ChangesWhenUpperCasedSpecialCasing for details) of the given ASCII code
* point.
*/
inline char ToLowerCase(char ch) {
 MOZ_ASSERT(static_cast<unsigned char>(ch) < 128);
 return latin1ToLowerCaseTable[uint8_t(ch)];
}

/**
* Returns true iff ToUpperCase(ch) != ch.
*
* This function isn't guaranteed to correctly handle code points for which
* |ChangesWhenUpperCasedSpecialCasing| returns true, so it is *not* always the
* same as the value of the Changes_When_Uppercased Unicode property value for
* the code point.
*/
inline bool ChangesWhenUpperCased(char16_t ch) {
 if (ch < 128) {
   return ch >= 'a' && ch <= 'z';
 }
 return CharInfo(ch).upperCase != 0;
}

/**
* Returns true iff ToUpperCase(ch) != ch.
*
* This function isn't guaranteed to correctly handle code points for which
* |ChangesWhenUpperCasedSpecialCasing| returns true, so it is *not* always the
* same as the value of the Changes_When_Uppercased Unicode property value for
* the code point.
*/
inline bool ChangesWhenUpperCased(JS::Latin1Char ch) {
 if (MOZ_LIKELY(ch < 128)) {
   return ch >= 'a' && ch <= 'z';
 }

 // U+00B5 and U+00E0 to U+00FF, except U+00F7, have an uppercase form.
 bool hasUpper =
     ch == MICRO_SIGN || (((ch & ~0x1F) == LATIN_SMALL_LETTER_A_WITH_GRAVE) &&
                          ch != DIVISION_SIGN);
 MOZ_ASSERT(hasUpper == ChangesWhenUpperCased(char16_t(ch)));
 return hasUpper;
}

// Returns true iff ToLowerCase(ch) != ch.
inline bool ChangesWhenLowerCased(char16_t ch) {
 if (ch < 128) {
   return ch >= 'A' && ch <= 'Z';
 }
 return CharInfo(ch).lowerCase != 0;
}

// Returns true iff ToLowerCase(ch) != ch.
inline bool ChangesWhenLowerCased(JS::Latin1Char ch) {
 return latin1ToLowerCaseTable[ch] != ch;
}

#define CHECK_RANGE(FROM, TO, LEAD, TRAIL_FROM, TRAIL_TO, DIFF) \
 if (lead == LEAD && trail >= TRAIL_FROM && trail <= TRAIL_TO) return true;

inline bool ChangesWhenUpperCasedNonBMP(char16_t lead, char16_t trail) {
 FOR_EACH_NON_BMP_UPPERCASE(CHECK_RANGE)
 return false;
}

inline bool ChangesWhenLowerCasedNonBMP(char16_t lead, char16_t trail) {
 FOR_EACH_NON_BMP_LOWERCASE(CHECK_RANGE)
 return false;
}

#undef CHECK_RANGE

inline char16_t ToUpperCaseNonBMPTrail(char16_t lead, char16_t trail) {
#define CALC_TRAIL(FROM, TO, LEAD, TRAIL_FROM, TRAIL_TO, DIFF)  \
 if (lead == LEAD && trail >= TRAIL_FROM && trail <= TRAIL_TO) \
   return trail + DIFF;
 FOR_EACH_NON_BMP_UPPERCASE(CALC_TRAIL)
#undef CALL_TRAIL

 return trail;
}

inline char16_t ToLowerCaseNonBMPTrail(char16_t lead, char16_t trail) {
#define CALC_TRAIL(FROM, TO, LEAD, TRAIL_FROM, TRAIL_TO, DIFF)  \
 if (lead == LEAD && trail >= TRAIL_FROM && trail <= TRAIL_TO) \
   return trail + DIFF;
 FOR_EACH_NON_BMP_LOWERCASE(CALC_TRAIL)
#undef CALL_TRAIL

 return trail;
}

/*
* Returns true if, independent of language/locale, the given UTF-16 code unit
* has a special upper case mapping.
*
* Unicode defines two case mapping modes:
*
*   1. "simple case mappings" (defined in UnicodeData.txt) for one-to-one
*      mappings that are always the same regardless of locale or context
*      within a string (e.g. "a"→"A").
*   2. "special case mappings" (defined in SpecialCasing.txt) for mappings
*      that alter string length (e.g. uppercasing "ß"→"SS") or where different
*      mappings occur depending on language/locale (e.g. uppercasing "i"→"I"
*      usually but "i"→"İ" in Turkish) or context within the string (e.g.
*      lowercasing "Σ" U+03A3 GREEK CAPITAL LETTER SIGMA to "ς" U+03C2 GREEK
*      SMALL LETTER FINAL SIGMA when the sigma appears [roughly speaking] at
*      the end of a word but "ς" U+03C3 GREEK SMALL LETTER SIGMA anywhere
*      else).
*
* The ChangesWhenUpperCased*() functions defined above will return true for
* code points that have simple case mappings, but they may not return the
* right result for code points that have special case mappings.  To correctly
* support full case mappings for all code points, callers must determine
* whether this function returns true or false for the code point, then use
* AppendUpperCaseSpecialCasing in the former case and ToUpperCase in the
* latter.
*
* NOTE: All special upper case mappings are unconditional (that is, they don't
*       depend on language/locale or context within the string) in Unicode 10.
*/
bool ChangesWhenUpperCasedSpecialCasing(char16_t ch);

/*
* Returns the length of the upper case mapping of |ch|.
*
* This function asserts if |ch| doesn't have a special upper case mapping.
*/
size_t LengthUpperCaseSpecialCasing(char16_t ch);

/*
* Appends the upper case mapping of |ch| to the given output buffer,
* starting at the provided index.
*
* This function asserts if |ch| doesn't have a special upper case mapping.
*/
void AppendUpperCaseSpecialCasing(char16_t ch, char16_t* elements,
                                 size_t* index);

class FoldingInfo {
public:
 uint16_t folding;
};

extern const uint8_t folding_index1[];
extern const uint8_t folding_index2[];
extern const FoldingInfo js_foldinfo[];

inline const FoldingInfo& CaseFoldInfo(char16_t code) {
 const size_t shift = 5;
 size_t index = folding_index1[code >> shift];
 index = folding_index2[(index << shift) + (code & ((1 << shift) - 1))];
 return js_foldinfo[index];
}

inline char16_t FoldCase(char16_t ch) {
 const FoldingInfo& info = CaseFoldInfo(ch);
 return uint16_t(ch) + info.folding;
}

inline bool IsSupplementary(char32_t codePoint) {
 return codePoint >= NonBMPMin && codePoint <= NonBMPMax;
}

inline bool IsLeadSurrogate(char32_t codePoint) {
 return codePoint >= LeadSurrogateMin && codePoint <= LeadSurrogateMax;
}

inline bool IsTrailSurrogate(char32_t codePoint) {
 return codePoint >= TrailSurrogateMin && codePoint <= TrailSurrogateMax;
}

/**
* True iff the given value is a UTF-16 surrogate.
*
* This function is intended for use in contexts where 32-bit values may need
* to be tested to see if they reside in the surrogate range, so it doesn't
* just take char16_t.
*/
inline bool IsSurrogate(char32_t codePoint) {
 return LeadSurrogateMin <= codePoint && codePoint <= TrailSurrogateMax;
}

inline char16_t LeadSurrogate(char32_t codePoint) {
 MOZ_ASSERT(IsSupplementary(codePoint));

 return char16_t((codePoint >> 10) + (LeadSurrogateMin - (NonBMPMin >> 10)));
}

inline char16_t TrailSurrogate(char32_t codePoint) {
 MOZ_ASSERT(IsSupplementary(codePoint));

 return char16_t((codePoint & 0x3FF) | TrailSurrogateMin);
}

inline void UTF16Encode(char32_t codePoint, char16_t* lead, char16_t* trail) {
 MOZ_ASSERT(IsSupplementary(codePoint));

 *lead = LeadSurrogate(codePoint);
 *trail = TrailSurrogate(codePoint);
}

inline void UTF16Encode(char32_t codePoint, char16_t* elements,
                       unsigned* index) {
 if (!IsSupplementary(codePoint)) {
   elements[(*index)++] = char16_t(codePoint);
 } else {
   elements[(*index)++] = LeadSurrogate(codePoint);
   elements[(*index)++] = TrailSurrogate(codePoint);
 }
}

inline char32_t UTF16Decode(char16_t lead, char16_t trail) {
 MOZ_ASSERT(IsLeadSurrogate(lead));
 MOZ_ASSERT(IsTrailSurrogate(trail));

 return (lead << 10) + trail +
        (NonBMPMin - (LeadSurrogateMin << 10) - TrailSurrogateMin);
}

} /* namespace unicode */
} /* namespace js */

#endif /* util_Unicode_h */