gecko/intl/unicharutil/util/nsBidiUtils.cpp

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * 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/. */
#include "nsBidiUtils.h"
#include "nsCharTraits.h"
#include "nsUnicodeProperties.h"

#define ARABIC_TO_HINDI_DIGIT_INCREMENT (START_HINDI_DIGITS - START_ARABIC_DIGITS)
#define PERSIAN_TO_HINDI_DIGIT_INCREMENT (START_HINDI_DIGITS - START_FARSI_DIGITS)
#define ARABIC_TO_PERSIAN_DIGIT_INCREMENT (START_FARSI_DIGITS - START_ARABIC_DIGITS)
#define NUM_TO_ARABIC(c) \
  ((((c)>=START_HINDI_DIGITS) && ((c)<=END_HINDI_DIGITS)) ? \
   ((c) - (uint16_t)ARABIC_TO_HINDI_DIGIT_INCREMENT) : \
   ((((c)>=START_FARSI_DIGITS) && ((c)<=END_FARSI_DIGITS)) ? \
    ((c) - (uint16_t)ARABIC_TO_PERSIAN_DIGIT_INCREMENT) : \
     (c)))
#define NUM_TO_HINDI(c) \
  ((((c)>=START_ARABIC_DIGITS) && ((c)<=END_ARABIC_DIGITS)) ? \
   ((c) + (uint16_t)ARABIC_TO_HINDI_DIGIT_INCREMENT): \
   ((((c)>=START_FARSI_DIGITS) && ((c)<=END_FARSI_DIGITS)) ? \
    ((c) + (uint16_t)PERSIAN_TO_HINDI_DIGIT_INCREMENT) : \
     (c)))
#define NUM_TO_PERSIAN(c) \
  ((((c)>=START_HINDI_DIGITS) && ((c)<=END_HINDI_DIGITS)) ? \
   ((c) - (uint16_t)PERSIAN_TO_HINDI_DIGIT_INCREMENT) : \
   ((((c)>=START_ARABIC_DIGITS) && ((c)<=END_ARABIC_DIGITS)) ? \
    ((c) + (uint16_t)ARABIC_TO_PERSIAN_DIGIT_INCREMENT) : \
     (c)))

PRUnichar HandleNumberInChar(PRUnichar aChar, bool aPrevCharArabic, uint32_t aNumFlag)
{
  // IBMBIDI_NUMERAL_NOMINAL *
  // IBMBIDI_NUMERAL_REGULAR
  // IBMBIDI_NUMERAL_HINDICONTEXT
  // IBMBIDI_NUMERAL_ARABIC
  // IBMBIDI_NUMERAL_HINDI

  switch (aNumFlag) {
    case IBMBIDI_NUMERAL_HINDI:
      return NUM_TO_HINDI(aChar);
    case IBMBIDI_NUMERAL_ARABIC:
      return NUM_TO_ARABIC(aChar);
    case IBMBIDI_NUMERAL_PERSIAN:
      return NUM_TO_PERSIAN(aChar);
    case IBMBIDI_NUMERAL_REGULAR:
    case IBMBIDI_NUMERAL_HINDICONTEXT:
    case IBMBIDI_NUMERAL_PERSIANCONTEXT:
      // for clipboard handling
      //XXX do we really want to convert numerals when copying text?
      if (aPrevCharArabic) {
        if (aNumFlag == IBMBIDI_NUMERAL_PERSIANCONTEXT)
          return NUM_TO_PERSIAN(aChar);
        else
          return NUM_TO_HINDI(aChar);
      }
      else
        return NUM_TO_ARABIC(aChar);
    case IBMBIDI_NUMERAL_NOMINAL:
    default:
      return aChar;
  }
}

nsresult HandleNumbers(PRUnichar* aBuffer, uint32_t aSize, uint32_t aNumFlag)
{
  uint32_t i;

  switch (aNumFlag) {
    case IBMBIDI_NUMERAL_HINDI:
    case IBMBIDI_NUMERAL_ARABIC:
    case IBMBIDI_NUMERAL_PERSIAN:
    case IBMBIDI_NUMERAL_REGULAR:
    case IBMBIDI_NUMERAL_HINDICONTEXT:
    case IBMBIDI_NUMERAL_PERSIANCONTEXT:
      for (i=0;i<aSize;i++)
        aBuffer[i] = HandleNumberInChar(aBuffer[i], !!(i>0 ? aBuffer[i-1] : 0), aNumFlag);
      break;
    case IBMBIDI_NUMERAL_NOMINAL:
    default:
      break;
  }
  return NS_OK;
}

#define LRM_CHAR 0x200e
#define LRE_CHAR 0x202a
#define RLO_CHAR 0x202e
bool IsBidiControl(uint32_t aChar)
{
  // This method is used when stripping Bidi control characters for
  // display, so it will return TRUE for LRM, RLM, LRE, RLE, PDF, LRO and RLO
  return ((LRE_CHAR <= aChar && aChar <= RLO_CHAR) ||
          ((aChar)&0xfffffe)==LRM_CHAR);
}

bool HasRTLChars(const nsAString& aString)
{
// This is used to determine whether to enable bidi if a string has 
// right-to-left characters. To simplify things, anything that could be a
// surrogate or RTL presentation form is covered just by testing >= 0xD800).
// It's fine to enable bidi in rare cases where it actually isn't needed.
  int32_t length = aString.Length();
  for (int32_t i = 0; i < length; i++) {
    PRUnichar ch = aString.CharAt(i);
    if (ch >= 0xD800 || IS_IN_BMP_RTL_BLOCK(ch)) {
      return true;
    }
  }
  return false;
}