/* Grapheme cluster break function.
   Copyright (C) 2010-2018 Free Software Foundation, Inc.
   Written by Ben Pfaff <blp@cs.stanford.edu>, 2010.

   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/>.  */

#include <config.h>

/* Specification.  */
#include "unigbrk.h"

/* Evaluates to true if there is an extended grapheme cluster break between
   code points with GBP_* values A and B, false if there is not.  The comments
   are the grapheme cluster boundary rules from in UAX #29. */
#define UC_IS_GRAPHEME_BREAK(A, B)                                      \
  (/* GB1 and GB2 are covered--just use a GBP_CONTROL character, such   \
      as 0, for sot and eot. */                                         \
                                                                        \
   /* GB3 */                                                            \
   (A) == GBP_CR && (B) == GBP_LF ? false :                             \
                                                                        \
   /* GB4 */                                                            \
   (A) == GBP_CONTROL || (A) == GBP_CR || (A) == GBP_LF ? true :        \
                                                                        \
   /* GB5 */                                                            \
   (B) == GBP_CONTROL || (B) == GBP_CR || (B) == GBP_LF ? true :        \
                                                                        \
   /* GB6 */                                                            \
   (A) == GBP_L && ((B) == GBP_L || (B) == GBP_V                        \
                    || (B) == GBP_LV || (B) == GBP_LVT) ? false :       \
                                                                        \
   /* GB7 */                                                            \
   ((A) == GBP_LV || (A) == GBP_V)                                      \
   && ((B) == GBP_V || (B) == GBP_T) ? false :                          \
                                                                        \
   /* GB8 */                                                            \
   ((A) == GBP_LVT || (A) == GBP_T) && (B) == GBP_T ? false :           \
                                                                        \
   /* GB9 */                                                            \
   (B) == GBP_EXTEND || (B) == GBP_ZWJ ? false :                        \
                                                                        \
   /* GB9a */                                                           \
   (B) == GBP_SPACINGMARK ? false :                                     \
                                                                        \
   /* GB9b */                                                           \
   (A) == GBP_PREPEND ? false :                                         \
                                                                        \
   /* GB10 -- incomplete */                                             \
   ((A) == GBP_EB || (A) == GBP_EBG) && (B) == GBP_EM ? false :         \
                                                                        \
   /* GB11 */                                                           \
   (A) == GBP_ZWJ && ((B) == GBP_GAZ || (B) == GBP_EBG) ? false         \
                                                                        \
   /* GB999 */                                                          \
   : true)

#define UC_GRAPHEME_BREAKS_FOR(A)                                       \
  (  (UC_IS_GRAPHEME_BREAK(A, GBP_OTHER)       << GBP_OTHER)            \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_CR)          << GBP_CR)               \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_LF)          << GBP_LF)               \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_CONTROL)     << GBP_CONTROL)          \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_EXTEND)      << GBP_EXTEND)           \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_PREPEND)     << GBP_PREPEND)          \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_SPACINGMARK) << GBP_SPACINGMARK)      \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_L)           << GBP_L)                \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_V)           << GBP_V)                \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_T)           << GBP_T)                \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_LV)          << GBP_LV)               \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_LVT)         << GBP_LVT)              \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_RI)          << GBP_RI)               \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_ZWJ)         << GBP_ZWJ)              \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_EB)          << GBP_EB)               \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_EM)          << GBP_EM)               \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_GAZ)         << GBP_GAZ)              \
   | (UC_IS_GRAPHEME_BREAK(A, GBP_EBG)         << GBP_EBG))

static const unsigned long int gb_table[18] =
  {
    UC_GRAPHEME_BREAKS_FOR(0),  /* GBP_OTHER */
    UC_GRAPHEME_BREAKS_FOR(1),  /* GBP_CR */
    UC_GRAPHEME_BREAKS_FOR(2),  /* GBP_LF */
    UC_GRAPHEME_BREAKS_FOR(3),  /* GBP_CONTROL */
    UC_GRAPHEME_BREAKS_FOR(4),  /* GBP_EXTEND */
    UC_GRAPHEME_BREAKS_FOR(5),  /* GBP_PREPEND */
    UC_GRAPHEME_BREAKS_FOR(6),  /* GBP_SPACINGMARK */
    UC_GRAPHEME_BREAKS_FOR(7),  /* GBP_L */
    UC_GRAPHEME_BREAKS_FOR(8),  /* GBP_V */
    UC_GRAPHEME_BREAKS_FOR(9),  /* GBP_T */
    UC_GRAPHEME_BREAKS_FOR(10), /* GBP_LV */
    UC_GRAPHEME_BREAKS_FOR(11), /* GBP_LVT */
    UC_GRAPHEME_BREAKS_FOR(12), /* GBP_RI */
    UC_GRAPHEME_BREAKS_FOR(13), /* GBP_ZWJ */
    UC_GRAPHEME_BREAKS_FOR(14), /* GBP_EB */
    UC_GRAPHEME_BREAKS_FOR(15), /* GBP_EM */
    UC_GRAPHEME_BREAKS_FOR(16), /* GBP_GAZ */
    UC_GRAPHEME_BREAKS_FOR(17), /* GBP_EBG */
  };

bool
uc_is_grapheme_break (ucs4_t a, ucs4_t b)
{
  int a_gcp, b_gcp;

  if ((a | b) < 0x300)
    {
      /* GB3 is the only relevant rule for this case. */
      return a != '\r' || b != '\n';
    }

  a_gcp = uc_graphemeclusterbreak_property (a);
  b_gcp = uc_graphemeclusterbreak_property (b);
  return (gb_table[a_gcp] >> b_gcp) & 1;
}
