unicode.cc.svn-base

Google浏览器V8内核代码

// Copyright 2007-2008 the V8 project authors. All rights reserved.
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//
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// This file was generated at 2008-09-08 11:13:45.862026

#include "unicode-inl.h"
#include <cstdlib>
#include <cstdio>

namespace unibrow {

/**
 * \file
 * Implementations of functions for working with unicode.
 */

typedef signed short int16_t;  // NOLINT
typedef unsigned short uint16_t;  // NOLINT

// All access to the character table should go through this function.
template <int D>
static inline uchar TableGet(const uint16_t* table, int index) {
  return table[D * index];
}

static inline uchar GetEntry(uint16_t entry) {
  return entry & 0x7fff;
}

static inline bool IsStart(uint16_t entry) {
  return (entry & (1 << 15)) != 0;
}

/**
 * Look up a character in the unicode table using a mix of binary and
 * interpolation search.  For a uniformly distributed array
 * interpolation search beats binary search by a wide margin.  However,
 * in this case interpolation search degenerates because of some very
 * high values in the lower end of the table so this function uses a
 * combination.  The average number of steps to look up the information
 * about a character is around 10, slightly higher if there is no
 * information available about the character.
 */
static bool LookupPredicate(const uint16_t* table, uint16_t size, uchar chr) {
  static const int kEntryDist = 1;
  uint16_t value = chr & 0x7fff;
  unsigned int low = 0;
  unsigned int high = size - 1;
  while (high != low) {
    unsigned int mid = low + ((high - low) >> 1);
    uchar current_value = GetEntry(TableGet<kEntryDist>(table, mid));
    // If we've found an entry less than or equal to this one, and the
    // next one is not also less than this one, we've arrived.
    if ((current_value <= value) &&
        (mid + 1 == size ||
         GetEntry(TableGet<kEntryDist>(table, mid + 1)) > value)) {
      low = mid;
      break;
    } else if (current_value < value) {
      low = mid + 1;
    } else if (current_value > value) {
      // If we've just checked the bottom-most value and it's not
      // the one we're looking for, we're done.
      if (mid == 0) break;
      high = mid - 1;
    }
  }
  uint16_t field = TableGet<kEntryDist>(table, low);
  return (GetEntry(field) == value) ||
          (GetEntry(field) < value && IsStart(field));
}

struct MultiCharacterSpecialCase {
  uint16_t length;
  uchar chars[kMaxCaseConvertedSize];
};

// Look up the mapping for the given character in the specified table,
// which is of the specified length and uses the specified special case
// mapping for multi-char mappings.  The next parameter is the character
// following the one to map.  The result will be written in to the result
// buffer and the number of characters written will be returned.  Finally,
// if the allow_caching_ptr is non-null then false will be stored in
// it if the result contains multiple characters or depends on the
// context.
static int LookupMapping(const uint16_t* table, uint16_t size,
    const MultiCharacterSpecialCase* multi_chars, uchar chr, uchar next,
    uchar* result, bool* allow_caching_ptr) {
  static const int kEntryDist = 2;
  uint16_t value = chr & 0x7fff;
  unsigned int low = 0;
  unsigned int high = size - 1;
  while (high != low) {
    unsigned int mid = low + ((high - low) >> 1);
    uchar current_value = GetEntry(TableGet<kEntryDist>(table, mid));
    // If we've found an entry less than or equal to this one, and the next one
    // is not also less than this one, we've arrived.
    if ((current_value <= value) &&
        (mid + 1 == size ||
         GetEntry(TableGet<kEntryDist>(table, mid + 1)) > value)) {
      low = mid;
      break;
    } else if (current_value < value) {
      low = mid + 1;
    } else if (current_value > value) {
      // If we've just checked the bottom-most value and it's not
      // the one we're looking for, we're done.
      if (mid == 0) break;
      high = mid - 1;
    }
  }
  uint16_t field = TableGet<kEntryDist>(table, low);
  bool found = (GetEntry(field) == value) ||
               (GetEntry(field) < value && IsStart(field));
  if (found) {
    int16_t value = table[2 * low + 1];
    if (value == 0) {
      // 0 means not present
      return 0;
    } else if ((value & 3) == 0) {
      // Low bits 0 means a constant offset from the given character.
      result[0] = chr + (value >> 2);
      return 1;
    } else if ((value & 3) == 1) {
      // Low bits 1 means a special case mapping
      if (allow_caching_ptr) *allow_caching_ptr = false;
      const MultiCharacterSpecialCase& mapping = multi_chars[value >> 2];
      for (int i = 0; i < mapping.length; i++)