text: // Copyright 2011 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_UNICODE_H_
  #define V8_UNICODE_H_
  
  #include <sys/types.h>
  #include "src/globals.h"
  #include "src/utils.h"
  /**
   * \file
   * Definitions and convenience functions for working with unicode.
   */
  
  namespace unibrow {
  
  typedef unsigned int uchar;
  typedef unsigned char byte;
  
  /**
   * The max length of the result of converting the case of a single
   * character.
   */
  const int kMaxMappingSize = 4;
  
  template <class T, int size = 256>
  class Predicate {
   public:
    inline Predicate() { }
    inline bool get(uchar c);
  
   private:
    friend class Test;
    bool CalculateValue(uchar c);
    class CacheEntry {
     public:
      inline CacheEntry()
          : bit_field_(CodePointField::encode(0) | ValueField::encode(0)) {}
      inline CacheEntry(uchar code_point, bool value)
          : bit_field_(CodePointField::encode(code_point) |
                       ValueField::encode(value)) {}
  
      uchar code_point() const { return CodePointField::decode(bit_field_); }
      bool value() const { return ValueField::decode(bit_field_); }
  
     private:
      class CodePointField : public v8::internal::BitField<uchar, 0, 21> {};
      class ValueField : public v8::internal::BitField<bool, 21, 1> {};
  
      uint32_t bit_field_;
    };
    static const int kSize = size;
    static const int kMask = kSize - 1;
    CacheEntry entries_[kSize];
  };
  
  
  // A cache used in case conversion.  It caches the value for characters
  // that either have no mapping or map to a single character independent
  // of context.  Characters that map to more than one character or that
  // map differently depending on context are always looked up.
  template <class T, int size = 256>
  class Mapping {
   public:
    inline Mapping() { }
    inline int get(uchar c, uchar n, uchar* result);
   private:
    friend class Test;
    int CalculateValue(uchar c, uchar n, uchar* result);
    struct CacheEntry {
      inline CacheEntry() : code_point_(kNoChar), offset_(0) { }
      inline CacheEntry(uchar code_point, signed offset)
        : code_point_(code_point),
          offset_(offset) { }
      uchar code_point_;
      signed offset_;
      static const int kNoChar = (1 << 21) - 1;
    };
    static const int kSize = size;
    static const int kMask = kSize - 1;
    CacheEntry entries_[kSize];
  };
  
  
  class UnicodeData {
   private:
    friend class Test;
    static int GetByteCount();
    static const uchar kMaxCodePoint;
  };
  
  
  class Utf16 {
   public:
    static inline bool IsSurrogatePair(int lead, int trail) {
      return IsLeadSurrogate(lead) && IsTrailSurrogate(trail);
    }
    static inline bool IsLeadSurrogate(int code) {
      if (code == kNoPreviousCharacter) return false;
      return (code & 0xfc00) == 0xd800;
    }
    static inline bool IsTrailSurrogate(int code) {
      if (code == kNoPreviousCharacter) return false;
      return (code & 0xfc00) == 0xdc00;
    }
  
    static inline int CombineSurrogatePair(uchar lead, uchar trail) {
      return 0x10000 + ((lead & 0x3ff) << 10) + (trail & 0x3ff);
    }
    static const int kNoPreviousCharacter = -1;
    static const uchar kMaxNonSurrogateCharCode = 0xffff;
    // Encoding a single UTF-16 code unit will produce 1, 2 or 3 bytes
    // of UTF-8 data.  The special case where the unit is a surrogate
    // trail produces 1 byte net, because the encoding of the pair is
    // 4 bytes and the 3 bytes that were used to encode the lead surrogate
    // can be reclaimed.
    static const int kMaxExtraUtf8BytesForOneUtf16CodeUnit = 3;
    // One UTF-16 surrogate is endoded (illegally) as 3 UTF-8 bytes.
    // The illegality stems from the surrogate not being part of a pair.
    static const int kUtf8BytesToCodeASurrogate = 3;
    static inline uint16_t LeadSurrogate(uint32_t char_code) {
      return 0xd800 + (((char_code - 0x10000) >> 10) & 0x3ff);
    }
    static inline uint16_t TrailSurrogate(uint32_t char_code) {
      return 0xdc00 + (char_code & 0x3ff);
    }
  };
  
  
  class Utf8 {
   public:
    static inline uchar Length(uchar chr, int previous);
    static inline unsigned EncodeOneByte(char* out, uint8_t c);
    static inline unsigned Encode(char* out,
                                  uchar c,
                                  int previous,
                                  bool replace_invalid = false);
    static uchar CalculateValue(const byte* str, size_t length, size_t* cursor);
  
    // The unicode replacement character, used to signal invalid unicode
    // sequences (e.g. an orphan surrogate) when converting to a UTF-8 encoding.
    static const uchar kBadChar = 0xFFFD;
    static const unsigned kMaxEncodedSize   = 4;
    static const unsigned kMaxOneByteChar   = 0x7f;
    static const unsigned kMaxTwoByteChar   = 0x7ff;
    static const unsigned kMaxThreeByteChar = 0xffff;
    static const unsigned kMaxFourByteChar  = 0x1fffff;
  
    // A single surrogate is coded as a 3 byte UTF-8 sequence, but two together
    // that match are coded as a 4 byte UTF-8 sequence.
    static const unsigned kBytesSavedByCombiningSurrogates = 2;
    static const unsigned kSizeOfUnmatchedSurrogate = 3;
    // The maximum size a single UTF-16 code unit may take up when encoded as
    // UTF-8.
    static const unsigned kMax16BitCodeUnitSize  = 3;
    static inline uchar ValueOf(const byte* str, size_t length, size_t* cursor);
  
    // Excludes non-characters from the set of valid code points.
    static inline bool IsValidCharacter(uchar c);
  
    static bool Validate(const byte* str, size_t length);
  };
  
  struct Uppercase {
    static bool Is(uchar c);
  };
  struct Lowercase {
    static bool Is(uchar c);
  };
  struct Letter {
    static bool Is(uchar c);
  };
  struct ID_Start {
    static bool Is(uchar c);
  };
  struct ID_Continue {
    static bool Is(uchar c);
  };
  struct WhiteSpace {
    static bool Is(uchar c);
  };
  struct LineTerminator {
    static bool Is(uchar c);
  };
  struct ToLowercase {
    static const int kMaxWidth = 3;
    static const bool kIsToLower = true;
    static int Convert(uchar c,
                       uchar n,
                       uchar* result,
                       bool* allow_caching_ptr);
  };
  struct ToUppercase {
    static const int kMaxWidth = 3;
    static const bool kIsToLower = false;
    static int Convert(uchar c,
                       uchar n,
                       uchar* result,
                       bool* allow_caching_ptr);
  };
  struct Ecma262Canonicalize {
    static const int kMaxWidth = 1;
    static int Convert(uchar c,
                       uchar n,
                       uchar* result,
                       bool* allow_caching_ptr);
  };
  struct Ecma262UnCanonicalize {
    static const int kMaxWidth = 4;
    static int Convert(uchar c,
                       uchar n,
                       uchar* result,
                       bool* allow_caching_ptr);
  };
  struct CanonicalizationRange {
    static const int kMaxWidth = 1;
    static int Convert(uchar c,
                       uchar n,
                       uchar* result,
                       bool* allow_caching_ptr);
  };
  
  }  // namespace unibrow
  
  #endif  // V8_UNICODE_H_
  