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      1 // Copyright 2011 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef V8_UNICODE_H_
      6 #define V8_UNICODE_H_
      7 
      8 #include <sys/types.h>
      9 #include "src/globals.h"
     10 #include "src/utils.h"
     11 /**
     12  * \file
     13  * Definitions and convenience functions for working with unicode.
     14  */
     15 
     16 namespace unibrow {
     17 
     18 typedef unsigned int uchar;
     19 typedef unsigned char byte;
     20 
     21 /**
     22  * The max length of the result of converting the case of a single
     23  * character.
     24  */
     25 const int kMaxMappingSize = 4;
     26 
     27 template <class T, int size = 256>
     28 class Predicate {
     29  public:
     30   inline Predicate() { }
     31   inline bool get(uchar c);
     32 
     33  private:
     34   friend class Test;
     35   bool CalculateValue(uchar c);
     36   class CacheEntry {
     37    public:
     38     inline CacheEntry()
     39         : bit_field_(CodePointField::encode(0) | ValueField::encode(0)) {}
     40     inline CacheEntry(uchar code_point, bool value)
     41         : bit_field_(CodePointField::encode(code_point) |
     42                      ValueField::encode(value)) {}
     43 
     44     uchar code_point() const { return CodePointField::decode(bit_field_); }
     45     bool value() const { return ValueField::decode(bit_field_); }
     46 
     47    private:
     48     class CodePointField : public v8::internal::BitField<uchar, 0, 21> {};
     49     class ValueField : public v8::internal::BitField<bool, 21, 1> {};
     50 
     51     uint32_t bit_field_;
     52   };
     53   static const int kSize = size;
     54   static const int kMask = kSize - 1;
     55   CacheEntry entries_[kSize];
     56 };
     57 
     58 
     59 // A cache used in case conversion.  It caches the value for characters
     60 // that either have no mapping or map to a single character independent
     61 // of context.  Characters that map to more than one character or that
     62 // map differently depending on context are always looked up.
     63 template <class T, int size = 256>
     64 class Mapping {
     65  public:
     66   inline Mapping() { }
     67   inline int get(uchar c, uchar n, uchar* result);
     68  private:
     69   friend class Test;
     70   int CalculateValue(uchar c, uchar n, uchar* result);
     71   struct CacheEntry {
     72     inline CacheEntry() : code_point_(kNoChar), offset_(0) { }
     73     inline CacheEntry(uchar code_point, signed offset)
     74       : code_point_(code_point),
     75         offset_(offset) { }
     76     uchar code_point_;
     77     signed offset_;
     78     static const int kNoChar = (1 << 21) - 1;
     79   };
     80   static const int kSize = size;
     81   static const int kMask = kSize - 1;
     82   CacheEntry entries_[kSize];
     83 };
     84 
     85 
     86 class UnicodeData {
     87  private:
     88   friend class Test;
     89   static int GetByteCount();
     90   static const uchar kMaxCodePoint;
     91 };
     92 
     93 
     94 class Utf16 {
     95  public:
     96   static inline bool IsSurrogatePair(int lead, int trail) {
     97     return IsLeadSurrogate(lead) && IsTrailSurrogate(trail);
     98   }
     99   static inline bool IsLeadSurrogate(int code) {
    100     if (code == kNoPreviousCharacter) return false;
    101     return (code & 0xfc00) == 0xd800;
    102   }
    103   static inline bool IsTrailSurrogate(int code) {
    104     if (code == kNoPreviousCharacter) return false;
    105     return (code & 0xfc00) == 0xdc00;
    106   }
    107 
    108   static inline int CombineSurrogatePair(uchar lead, uchar trail) {
    109     return 0x10000 + ((lead & 0x3ff) << 10) + (trail & 0x3ff);
    110   }
    111   static const int kNoPreviousCharacter = -1;
    112   static const uchar kMaxNonSurrogateCharCode = 0xffff;
    113   // Encoding a single UTF-16 code unit will produce 1, 2 or 3 bytes
    114   // of UTF-8 data.  The special case where the unit is a surrogate
    115   // trail produces 1 byte net, because the encoding of the pair is
    116   // 4 bytes and the 3 bytes that were used to encode the lead surrogate
    117   // can be reclaimed.
    118   static const int kMaxExtraUtf8BytesForOneUtf16CodeUnit = 3;
    119   // One UTF-16 surrogate is endoded (illegally) as 3 UTF-8 bytes.
    120   // The illegality stems from the surrogate not being part of a pair.
    121   static const int kUtf8BytesToCodeASurrogate = 3;
    122   static inline uint16_t LeadSurrogate(uint32_t char_code) {
    123     return 0xd800 + (((char_code - 0x10000) >> 10) & 0x3ff);
    124   }
    125   static inline uint16_t TrailSurrogate(uint32_t char_code) {
    126     return 0xdc00 + (char_code & 0x3ff);
    127   }
    128 };
    129 
    130 
    131 class Utf8 {
    132  public:
    133   static inline uchar Length(uchar chr, int previous);
    134   static inline unsigned EncodeOneByte(char* out, uint8_t c);
    135   static inline unsigned Encode(char* out,
    136                                 uchar c,
    137                                 int previous,
    138                                 bool replace_invalid = false);
    139   static uchar CalculateValue(const byte* str, size_t length, size_t* cursor);
    140 
    141   // The unicode replacement character, used to signal invalid unicode
    142   // sequences (e.g. an orphan surrogate) when converting to a UTF-8 encoding.
    143   static const uchar kBadChar = 0xFFFD;
    144   static const unsigned kMaxEncodedSize   = 4;
    145   static const unsigned kMaxOneByteChar   = 0x7f;
    146   static const unsigned kMaxTwoByteChar   = 0x7ff;
    147   static const unsigned kMaxThreeByteChar = 0xffff;
    148   static const unsigned kMaxFourByteChar  = 0x1fffff;
    149 
    150   // A single surrogate is coded as a 3 byte UTF-8 sequence, but two together
    151   // that match are coded as a 4 byte UTF-8 sequence.
    152   static const unsigned kBytesSavedByCombiningSurrogates = 2;
    153   static const unsigned kSizeOfUnmatchedSurrogate = 3;
    154   // The maximum size a single UTF-16 code unit may take up when encoded as
    155   // UTF-8.
    156   static const unsigned kMax16BitCodeUnitSize  = 3;
    157   static inline uchar ValueOf(const byte* str, size_t length, size_t* cursor);
    158 };
    159 
    160 struct Uppercase {
    161   static bool Is(uchar c);
    162 };
    163 struct Lowercase {
    164   static bool Is(uchar c);
    165 };
    166 struct Letter {
    167   static bool Is(uchar c);
    168 };
    169 struct ID_Start {
    170   static bool Is(uchar c);
    171 };
    172 struct ID_Continue {
    173   static bool Is(uchar c);
    174 };
    175 struct WhiteSpace {
    176   static bool Is(uchar c);
    177 };
    178 struct LineTerminator {
    179   static bool Is(uchar c);
    180 };
    181 struct ToLowercase {
    182   static const int kMaxWidth = 3;
    183   static const bool kIsToLower = true;
    184   static int Convert(uchar c,
    185                      uchar n,
    186                      uchar* result,
    187                      bool* allow_caching_ptr);
    188 };
    189 struct ToUppercase {
    190   static const int kMaxWidth = 3;
    191   static const bool kIsToLower = false;
    192   static int Convert(uchar c,
    193                      uchar n,
    194                      uchar* result,
    195                      bool* allow_caching_ptr);
    196 };
    197 struct Ecma262Canonicalize {
    198   static const int kMaxWidth = 1;
    199   static int Convert(uchar c,
    200                      uchar n,
    201                      uchar* result,
    202                      bool* allow_caching_ptr);
    203 };
    204 struct Ecma262UnCanonicalize {
    205   static const int kMaxWidth = 4;
    206   static int Convert(uchar c,
    207                      uchar n,
    208                      uchar* result,
    209                      bool* allow_caching_ptr);
    210 };
    211 struct CanonicalizationRange {
    212   static const int kMaxWidth = 1;
    213   static int Convert(uchar c,
    214                      uchar n,
    215                      uchar* result,
    216                      bool* allow_caching_ptr);
    217 };
    218 
    219 }  // namespace unibrow
    220 
    221 #endif  // V8_UNICODE_H_
    222