/* Word breaks in UTF-8/UTF-16/UTF-32 strings.  -*- coding: utf-8 -*-
   Copyright (C) 2009-2018 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2009.

   This program is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

void
FUNC (const UNIT *s, size_t n, char *p)
{
  if (n > 0)
    {
      const UNIT *s_end = s + n;

      /* Word break property of the last character.
         -1 at the very beginning of the string.  */
      int last_char_prop = -1;

      /* Format and Extend characters are ignored; this means, the mostly used
         unit is the complex character (= character with subsequent ignored
         characters).
         Word break property of the last complex character.
         -1 at the very beginning of the string.  */
      int last_compchar_prop = -1;
      char *last_compchar_ptr = NULL;

      /* For recognizing rules involving 3 complex characters:
         Word break property of the second-to-last complex character.
         -1 at the very beginning of the string.  */
      int secondlast_compchar_prop = -1;

      size_t ri_count = 0;

      /* Don't break inside multibyte characters.  */
      memset (p, 0, n);

      while (s < s_end)
        {
          ucs4_t uc;
          int count = U_MBTOUC_UNSAFE (&uc, s, s_end - s);
          int prop = uc_wordbreak_property (uc);

          /* No break at the start of the string.  */
          if (last_char_prop >= 0)
            {
              /* No break between CR and LF (WB3).  */
              if (last_char_prop == WBP_CR && prop == WBP_LF)
                /* *p = 0 */;
              /* Break before and after newlines (WB3a, WB3b).  */
              else if ((last_char_prop == WBP_CR
                        || last_char_prop == WBP_LF
                        || last_char_prop == WBP_NEWLINE)
                       || (prop == WBP_CR
                           || prop == WBP_LF
                           || prop == WBP_NEWLINE))
                *p = 1;
              /* No break within emoji zwj sequence (WB3c).  */
              else if (last_char_prop == WBP_ZWJ &&
                       (prop == WBP_GAZ || prop == WBP_EBG))
                /* *p = 0 */;
              /* Ignore Format and Extend characters.  */
              else if (!(prop == WBP_EXTEND || prop == WBP_FORMAT || prop == WBP_ZWJ))
                {
                  /* No break in these situations (see UAX #29):

                      secondlast          last             current

    (ALetter | HL)   (MidLetter | MidNumLet | SQ) × (ALetter | HL)      (WB7)
    (ALetter | HL) × (MidLetter | MidNumLet | SQ)   (ALetter | HL)      (WB6)
                  Numeric   (MidNum | MidNumLet | SQ)    × Numeric      (WB11)
                  Numeric × (MidNum | MidNumLet | SQ)      Numeric      (WB12)
                                                        HL × DQ HL      (WB7b)
                                                        HL DQ × HL      (WB7c)
                                                ^ (RI RI)* RI × RI      (WB15)
                                            [^RI] (RI RI)* RI × RI      (WB16)
                   */
                  /* No break across certain punctuation.  Also, disable word
                     breaks that were recognized earlier (due to lookahead of
                     only one complex character).  */
                  if (((prop == WBP_ALETTER
                        || prop == WBP_HL)
                       && (last_compchar_prop == WBP_MIDLETTER
                           || last_compchar_prop == WBP_MIDNUMLET
                           || last_compchar_prop == WBP_SQ)
                       && (secondlast_compchar_prop == WBP_ALETTER
                           || secondlast_compchar_prop == WBP_HL))
                      || (prop == WBP_NUMERIC
                          && (last_compchar_prop == WBP_MIDNUM
                              || last_compchar_prop == WBP_MIDNUMLET
                              || last_compchar_prop == WBP_SQ)
                          && secondlast_compchar_prop == WBP_NUMERIC)
                      || (prop == WBP_HL
                          && last_compchar_prop == WBP_DQ
                          && secondlast_compchar_prop == WBP_HL))
                    {
                      *last_compchar_ptr = 0;
                      /* *p = 0; */
                    }
                  /* Break before RI, if odd number of RI's are
                     preceding (WB15, WB16).  */
                  else if (last_compchar_prop == WBP_RI && prop == WBP_RI)
                    {
                      if (ri_count % 2 == 0)
                        *p = 1;
                      /* else *p = 0 */
                    }
                  /* Break after Format and Extend character.  */
                  else if (last_compchar_prop == WBP_EXTEND
                           || last_compchar_prop == WBP_FORMAT)
                    *p = 1;
                  else
                    {
                      int last_compchar_index =
                        uniwbrk_prop_index[last_compchar_prop];
                      int index = uniwbrk_prop_index[prop];

                      /* Break between unknown pair (WB999).  */
                      if (last_compchar_index < 0 || index < 0)
                        *p = 1;
                      /* Perform a single table lookup.  */
                      else if (uniwbrk_table[last_compchar_index][index])
                        *p = 1;
                      /* else *p = 0; */
                    }
                }
            }

          last_char_prop = prop;

          /* Ignore Format and Extend characters, except at the
             start of the line.  */
          if (last_compchar_prop < 0
              || last_compchar_prop == WBP_CR
              || last_compchar_prop == WBP_LF
              || last_compchar_prop == WBP_NEWLINE
              || !(prop == WBP_EXTEND || prop == WBP_FORMAT || prop == WBP_ZWJ))
            {
              secondlast_compchar_prop = last_compchar_prop;
              last_compchar_prop = prop;
              last_compchar_ptr = p;

              if (prop == WBP_RI)
                ri_count++;
              else
                ri_count = 0;
            }

          s += count;
          p += count;
        }
    }
}
