src/cobalt/base/unicode/character.cc

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#include <algorithm>

#include "cobalt/base/unicode/character.h"

namespace base {
namespace unicode {
namespace {

// Takes a flattened list of closed intervals
template <class T, size_t size>
bool ValueInIntervalList(const T(&intervalList)[size], const T& value) {
  const T* bound =
      std::upper_bound(&intervalList[0], &intervalList[size], value);
  if ((bound - intervalList) % 2 == 1) return true;
  return bound > intervalList && *(bound - 1) == value;
}

}  // namespace

bool ContainsComplexScript(const UChar* characters, unsigned len) {
  static const UChar complexCodePathRanges[] = {
      // U+02E5 through U+02E9 (Modifier Letters : Tone letters)
      0x2E5, 0x2E9,
      // U+0300 through U+036F Combining diacritical marks
      0x300, 0x36F,
      // U+0591 through U+05CF excluding U+05BE Hebrew combining marks, ...
      0x0591, 0x05BD,
      // ... Hebrew punctuation Paseq, Sof Pasuq and Nun Hafukha
      0x05BF, 0x05CF,
      // U+0600 through U+109F Arabic, Syriac, Thaana, NKo, Samaritan, Mandaic,
      // Devanagari, Bengali, Gurmukhi, Gujarati, Oriya, Tamil, Telugu, Kannada,
      // Malayalam, Sinhala, Thai, Lao, Tibetan, Myanmar
      0x0600, 0x109F,
      // U+1100 through U+11FF Hangul Jamo (only Ancient Korean should be left
      // here if you precompose; Modern Korean will be precomposed as a result
      // of step A)
      0x1100, 0x11FF,
      // U+135D through U+135F Ethiopic combining marks
      0x135D, 0x135F,
      // U+1780 through U+18AF Tagalog, Hanunoo, Buhid, Taghanwa, Khmer,
      // Mongolian
      0x1700, 0x18AF,
      // U+1900 through U+194F Limbu (Unicode 4.0)
      0x1900, 0x194F,
      // U+1980 through U+19DF New Tai Lue
      0x1980, 0x19DF,
      // U+1A00 through U+1CFF Buginese, Tai Tham, Balinese, Batak, Lepcha,
      // Vedic
      0x1A00, 0x1CFF,
      // U+1DC0 through U+1DFF Combining diacritical mark supplement
      0x1DC0, 0x1DFF,
      // U+20D0 through U+20FF Combining marks for symbols
      0x20D0, 0x20FF,
      // U+2CEF through U+2CF1 Combining marks for Coptic
      0x2CEF, 0x2CF1,
      // U+302A through U+302F Ideographic and Hangul Tone marks
      0x302A, 0x302F,
      // Combining Katakana-Hiragana Voiced/Semi-voiced Sound Mark
      0x3099, 0x309A,
      // U+A67C through U+A67D Combining marks for old Cyrillic
      0xA67C, 0xA67D,
      // U+A6F0 through U+A6F1 Combining mark for Bamum
      0xA6F0, 0xA6F1,
      // U+A800 through U+ABFF Nagri, Phags-pa, Saurashtra, Devanagari Extended,
      // Hangul Jamo Ext. A, Javanese, Myanmar Extended A, Tai Viet, Meetei
      // Mayek
      0xA800, 0xABFF,
      // U+D7B0 through U+D7FF Hangul Jamo Ext. B
      0xD7B0, 0xD7FF,
      // U+FE00 through U+FE0F Unicode variation selectors
      0xFE00, 0xFE0F,
      // U+FE20 through U+FE2F Combining half marks
      0xFE20, 0xFE2F};

  for (unsigned i = 0; i < len; i++) {
    const UChar c = characters[i];

    // Shortcut for common case
    if (c < 0x2E5) {
      continue;
    }

    // Surrogate pairs
    if (c > 0xD7FF && c <= 0xDBFF) {
      if (i == len - 1) {
        continue;
      }

      UChar next = characters[++i];
      if (!U16_IS_TRAIL(next)) {
        continue;
      }

      UChar32 supplementaryCharacter = U16_GET_SUPPLEMENTARY(c, next);

      // U+1F1E6 through U+1F1FF Regional Indicator Symbols
      if (supplementaryCharacter < 0x1F1E6) {
        continue;
      }
      if (supplementaryCharacter <= 0x1F1FF) {
        return true;
      }

      // Man and Woman Emojies, in order to support emoji joiner combinations
      // for family and couple pictographs.
      // Compare http://unicode.org/reports/tr51/#Emoji_ZWJ_Sequences
      if (supplementaryCharacter < 0x1F468) {
        continue;
      }
      if (supplementaryCharacter <= 0x1F469) {
        return true;
      }

      // U+E0100 through U+E01EF Unicode variation selectors.
      if (supplementaryCharacter < 0xE0100) {
        continue;
      }
      if (supplementaryCharacter <= 0xE01EF) {
        return true;
      }

      // FIXME: Check for Brahmi (U+11000 block), Kaithi (U+11080 block) and
      // other complex scripts in plane 1 or higher.
      continue;
    }

    // Search for other Complex cases
    if (ValueInIntervalList(complexCodePathRanges, c)) {
      return true;
    }
  }

  return false;
}

bool TreatAsSpace(UChar32 c) {
  return c == kSpaceCharacter || c == kHorizontalTabulationCharacter ||
         c == kNewLineCharacter || c == kFormFeedCharacter ||
         c == kCarriageReturnCharacter || c == kNoBreakSpaceCharacter;
}

bool TreatAsZeroWidthSpace(UChar32 c) {
  if (TreatAsZeroWidthSpaceInComplexScript(c)) {
    return true;
  }

  switch (c) {
    case kActivateArabicFormShapingCharacter:
    case kActivateSymmetricSwappingCharacter:
    case kArabicLetterMarkCharacter:
    case kFirstStrongIsolateCharacter:
    case kInhibitArabicFormShapingCharacter:
    case kInhibitSymmetricSwappingCharacter:
    case kLeftToRightIsolateCharacter:
    case kNationalDigitShapesCharacter:
    case kNominalDigitShapesCharacter:
    case kPopDirectionalFormattingCharacter:
    case kPopDirectionalIsolateCharacter:
    case kRightToLeftIsolateCharacter:
    case kSoftHyphenCharacter:
    case kZeroWidthNonJoinerCharacter:
    case kZeroWidthJoinerCharacter:
      return true;
  }

  return false;
}

bool TreatAsZeroWidthSpaceInComplexScript(UChar32 c) {
  return c < 0x20                    // ASCII Control Characters
         || (c >= 0x7F && c < 0xA0)  // ASCII Delete .. No-break spaceCharacter
         || c == kZeroWidthSpaceCharacter ||
         (c >= kLeftToRightMarkCharacter && c <= kRightToLeftMarkCharacter) ||
         (c >= kLeftToRightEmbeddingCharacter &&
          c <= kRightToLeftOverrideCharacter) ||
         c == kZeroWidthNoBreakSpaceCharacter ||
         c == kObjectReplacementCharacter || IsEmojiModifier(c);
}

bool IsEmojiModifier(UChar32 c) { return c >= 0x1F3FB && c <= 0x1F3FF; }

UChar32 NormalizeSpaces(UChar32 character) {
  if (TreatAsSpace(character)) {
    return kSpaceCharacter;
  }

  if (TreatAsZeroWidthSpace(character)) {
    return kZeroWidthSpaceCharacter;
  }

  return character;
}

UChar32 NormalizeSpacesInComplexScript(UChar32 character) {
  if (TreatAsSpace(character)) {
    return kSpaceCharacter;
  }

  if (TreatAsZeroWidthSpaceInComplexScript(character)) {
    return kZeroWidthSpaceCharacter;
  }

  return character;
}

}  // namespace unicode
}  // namespace base