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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/third_party/utf8-decoder/utf8-decoder.h"
     11 #include "src/utils.h"
     12 /**
     13  * \file
     14  * Definitions and convenience functions for working with unicode.
     15  */
     16 
     17 namespace unibrow {
     18 
     19 typedef unsigned int uchar;
     20 typedef unsigned char byte;
     21 
     22 /**
     23  * The max length of the result of converting the case of a single
     24  * character.
     25  */
     26 const int kMaxMappingSize = 4;
     27 
     28 template <class T, int size = 256>
     29 class Predicate {
     30  public:
     31   inline Predicate() { }
     32   inline bool get(uchar c);
     33 
     34  private:
     35   friend class Test;
     36   bool CalculateValue(uchar c);
     37   class CacheEntry {
     38    public:
     39     inline CacheEntry()
     40         : bit_field_(CodePointField::encode(0) | ValueField::encode(0)) {}
     41     inline CacheEntry(uchar code_point, bool value)
     42         : bit_field_(
     43               CodePointField::encode(CodePointField::kMask & code_point) |
     44               ValueField::encode(value)) {
     45       DCHECK_IMPLIES((CodePointField::kMask & code_point) != code_point,
     46                      code_point == static_cast<uchar>(-1));
     47     }
     48 
     49     uchar code_point() const { return CodePointField::decode(bit_field_); }
     50     bool value() const { return ValueField::decode(bit_field_); }
     51 
     52    private:
     53     class CodePointField : public v8::internal::BitField<uchar, 0, 21> {};
     54     class ValueField : public v8::internal::BitField<bool, 21, 1> {};
     55 
     56     uint32_t bit_field_;
     57   };
     58   static const int kSize = size;
     59   static const int kMask = kSize - 1;
     60   CacheEntry entries_[kSize];
     61 };
     62 
     63 
     64 // A cache used in case conversion.  It caches the value for characters
     65 // that either have no mapping or map to a single character independent
     66 // of context.  Characters that map to more than one character or that
     67 // map differently depending on context are always looked up.
     68 template <class T, int size = 256>
     69 class Mapping {
     70  public:
     71   inline Mapping() { }
     72   inline int get(uchar c, uchar n, uchar* result);
     73  private:
     74   friend class Test;
     75   int CalculateValue(uchar c, uchar n, uchar* result);
     76   struct CacheEntry {
     77     inline CacheEntry() : code_point_(kNoChar), offset_(0) { }
     78     inline CacheEntry(uchar code_point, signed offset)
     79       : code_point_(code_point),
     80         offset_(offset) { }
     81     uchar code_point_;
     82     signed offset_;
     83     static const int kNoChar = (1 << 21) - 1;
     84   };
     85   static const int kSize = size;
     86   static const int kMask = kSize - 1;
     87   CacheEntry entries_[kSize];
     88 };
     89 
     90 
     91 class UnicodeData {
     92  private:
     93   friend class Test;
     94   static int GetByteCount();
     95   static const uchar kMaxCodePoint;
     96 };
     97 
     98 
     99 class Utf16 {
    100  public:
    101   static const int kNoPreviousCharacter = -1;
    102   static inline bool IsSurrogatePair(int lead, int trail) {
    103     return IsLeadSurrogate(lead) && IsTrailSurrogate(trail);
    104   }
    105   static inline bool IsLeadSurrogate(int code) {
    106     return (code & 0xfc00) == 0xd800;
    107   }
    108   static inline bool IsTrailSurrogate(int code) {
    109     return (code & 0xfc00) == 0xdc00;
    110   }
    111 
    112   static inline int CombineSurrogatePair(uchar lead, uchar trail) {
    113     return 0x10000 + ((lead & 0x3ff) << 10) + (trail & 0x3ff);
    114   }
    115   static const uchar kMaxNonSurrogateCharCode = 0xffff;
    116   // Encoding a single UTF-16 code unit will produce 1, 2 or 3 bytes
    117   // of UTF-8 data.  The special case where the unit is a surrogate
    118   // trail produces 1 byte net, because the encoding of the pair is
    119   // 4 bytes and the 3 bytes that were used to encode the lead surrogate
    120   // can be reclaimed.
    121   static const int kMaxExtraUtf8BytesForOneUtf16CodeUnit = 3;
    122   // One UTF-16 surrogate is endoded (illegally) as 3 UTF-8 bytes.
    123   // The illegality stems from the surrogate not being part of a pair.
    124   static const int kUtf8BytesToCodeASurrogate = 3;
    125   static inline uint16_t LeadSurrogate(uint32_t char_code) {
    126     return 0xd800 + (((char_code - 0x10000) >> 10) & 0x3ff);
    127   }
    128   static inline uint16_t TrailSurrogate(uint32_t char_code) {
    129     return 0xdc00 + (char_code & 0x3ff);
    130   }
    131 };
    132 
    133 class V8_EXPORT_PRIVATE Utf8 {
    134  public:
    135   using State = Utf8DfaDecoder::State;
    136 
    137   static inline uchar Length(uchar chr, int previous);
    138   static inline unsigned EncodeOneByte(char* out, uint8_t c);
    139   static inline unsigned Encode(char* out,
    140                                 uchar c,
    141                                 int previous,
    142                                 bool replace_invalid = false);
    143   static uchar CalculateValue(const byte* str, size_t length, size_t* cursor);
    144 
    145   // The unicode replacement character, used to signal invalid unicode
    146   // sequences (e.g. an orphan surrogate) when converting to a UTF-8 encoding.
    147   static const uchar kBadChar = 0xFFFD;
    148   static const uchar kBufferEmpty = 0x0;
    149   static const uchar kIncomplete = 0xFFFFFFFC;  // any non-valid code point.
    150   static const unsigned kMaxEncodedSize   = 4;
    151   static const unsigned kMaxOneByteChar   = 0x7f;
    152   static const unsigned kMaxTwoByteChar   = 0x7ff;
    153   static const unsigned kMaxThreeByteChar = 0xffff;
    154   static const unsigned kMaxFourByteChar  = 0x1fffff;
    155 
    156   // A single surrogate is coded as a 3 byte UTF-8 sequence, but two together
    157   // that match are coded as a 4 byte UTF-8 sequence.
    158   static const unsigned kBytesSavedByCombiningSurrogates = 2;
    159   static const unsigned kSizeOfUnmatchedSurrogate = 3;
    160   // The maximum size a single UTF-16 code unit may take up when encoded as
    161   // UTF-8.
    162   static const unsigned kMax16BitCodeUnitSize  = 3;
    163   static inline uchar ValueOf(const byte* str, size_t length, size_t* cursor);
    164 
    165   typedef uint32_t Utf8IncrementalBuffer;
    166   static uchar ValueOfIncremental(byte next_byte, size_t* cursor, State* state,
    167                                   Utf8IncrementalBuffer* buffer);
    168   static uchar ValueOfIncrementalFinish(State* state);
    169 
    170   // Excludes non-characters from the set of valid code points.
    171   static inline bool IsValidCharacter(uchar c);
    172 
    173   // Validate if the input has a valid utf-8 encoding. Unlike JS source code
    174   // this validation function will accept any unicode code point, including
    175   // kBadChar and BOMs.
    176   //
    177   // This method checks for:
    178   // - valid utf-8 endcoding (e.g. no over-long encodings),
    179   // - absence of surrogates,
    180   // - valid code point range.
    181   static bool ValidateEncoding(const byte* str, size_t length);
    182 };
    183 
    184 struct Uppercase {
    185   static bool Is(uchar c);
    186 };
    187 struct Letter {
    188   static bool Is(uchar c);
    189 };
    190 #ifndef V8_INTL_SUPPORT
    191 struct V8_EXPORT_PRIVATE ID_Start {
    192   static bool Is(uchar c);
    193 };
    194 struct V8_EXPORT_PRIVATE ID_Continue {
    195   static bool Is(uchar c);
    196 };
    197 struct V8_EXPORT_PRIVATE WhiteSpace {
    198   static bool Is(uchar c);
    199 };
    200 #endif  // !V8_INTL_SUPPORT
    201 
    202 // LineTerminator:       'JS_Line_Terminator' in point.properties
    203 // ES#sec-line-terminators lists exactly 4 code points:
    204 // LF (U+000A), CR (U+000D), LS(U+2028), PS(U+2029)
    205 V8_INLINE bool IsLineTerminator(uchar c) {
    206   return c == 0x000A || c == 0x000D || c == 0x2028 || c == 0x2029;
    207 }
    208 
    209 V8_INLINE bool IsStringLiteralLineTerminator(uchar c) {
    210   return c == 0x000A || c == 0x000D;
    211 }
    212 
    213 #ifndef V8_INTL_SUPPORT
    214 struct ToLowercase {
    215   static const int kMaxWidth = 3;
    216   static const bool kIsToLower = true;
    217   static int Convert(uchar c,
    218                      uchar n,
    219                      uchar* result,
    220                      bool* allow_caching_ptr);
    221 };
    222 struct ToUppercase {
    223   static const int kMaxWidth = 3;
    224   static const bool kIsToLower = false;
    225   static int Convert(uchar c,
    226                      uchar n,
    227                      uchar* result,
    228                      bool* allow_caching_ptr);
    229 };
    230 #endif
    231 struct Ecma262Canonicalize {
    232   static const int kMaxWidth = 1;
    233   static int Convert(uchar c,
    234                      uchar n,
    235                      uchar* result,
    236                      bool* allow_caching_ptr);
    237 };
    238 struct Ecma262UnCanonicalize {
    239   static const int kMaxWidth = 4;
    240   static int Convert(uchar c,
    241                      uchar n,
    242                      uchar* result,
    243                      bool* allow_caching_ptr);
    244 };
    245 struct CanonicalizationRange {
    246   static const int kMaxWidth = 1;
    247   static int Convert(uchar c,
    248                      uchar n,
    249                      uchar* result,
    250                      bool* allow_caching_ptr);
    251 };
    252 
    253 }  // namespace unibrow
    254 
    255 #endif  // V8_UNICODE_H_
    256