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/* Line breaking of UTF-32 strings.
   Copyright (C) 2001-2003, 2006-2009 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2001.

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

   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 <http://www.gnu.org/licenses/>.  */

#include <config.h>

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

#include <stdlib.h>

#include "unilbrk/lbrktables.h"
#include "uniwidth/cjk.h"

void
u32_possible_linebreaks (const uint32_t *s, size_t n, const char *encoding, char *p)
{
  int LBP_AI_REPLACEMENT = (is_cjk_encoding (encoding) ? LBP_ID : LBP_AL);
  const uint32_t *s_end = s + n;
  int last_prop = LBP_BK; /* line break property of last non-space character */
  char *seen_space = NULL; /* Was a space seen after the last non-space character? */
  char *seen_space2 = NULL; /* At least two spaces after the last non-space? */

  while (s < s_end)
    {
      ucs4_t uc = *s;
      int prop = unilbrkprop_lookup (uc);

      if (prop == LBP_BK)
	{
	  /* Mandatory break.  */
	  *p = UC_BREAK_MANDATORY;
	  last_prop = LBP_BK;
	  seen_space = NULL;
	  seen_space2 = NULL;
	}
      else
	{
	  char *q;

	  /* Resolve property values whose behaviour is not fixed.  */
	  switch (prop)
	    {
	    case LBP_AI:
	      /* Resolve ambiguous.  */
	      prop = LBP_AI_REPLACEMENT;
	      break;
	    case LBP_CB:
	      /* This is arbitrary.  */
	      prop = LBP_ID;
	      break;
	    case LBP_SA:
	      /* We don't handle complex scripts yet.
		 Treat LBP_SA like LBP_XX.  */
	    case LBP_XX:
	      /* This is arbitrary.  */
	      prop = LBP_AL;
	      break;
	    }

	  /* Deal with spaces and combining characters.  */
	  q = p;
	  if (prop == LBP_SP)
	    {
	      /* Don't break just before a space.  */
	      *p = UC_BREAK_PROHIBITED;
	      seen_space2 = seen_space;
	      seen_space = p;
	    }
	  else if (prop == LBP_ZW)
	    {
	      /* Don't break just before a zero-width space.  */
	      *p = UC_BREAK_PROHIBITED;
	      last_prop = LBP_ZW;
	      seen_space = NULL;
	      seen_space2 = NULL;
	    }
	  else if (prop == LBP_CM)
	    {
	      /* Don't break just before a combining character, except immediately after a
		 zero-width space.  */
	      if (last_prop == LBP_ZW)
		{
		  /* Break after zero-width space.  */
		  *p = UC_BREAK_POSSIBLE;
		  /* A combining character turns a preceding space into LBP_ID.  */
		  last_prop = LBP_ID;
		}
	      else
		{
		  *p = UC_BREAK_PROHIBITED;
		  /* A combining character turns a preceding space into LBP_ID.  */
		  if (seen_space != NULL)
		    {
		      q = seen_space;
		      seen_space = seen_space2;
		      prop = LBP_ID;
		      goto lookup_via_table;
		    }
		}
	    }
	  else
	    {
	     lookup_via_table:
	      /* prop must be usable as an index for table 7.3 of UTR #14.  */
	      if (!(prop >= 0 && prop < sizeof (unilbrk_table) / sizeof (unilbrk_table[0])))
		abort ();

	      if (last_prop == LBP_BK)
		{
		  /* Don't break at the beginning of a line.  */
		  *q = UC_BREAK_PROHIBITED;
		}
	      else if (last_prop == LBP_ZW)
		{
		  /* Break after zero-width space.  */
		  *q = UC_BREAK_POSSIBLE;
		}
	      else
		{
		  switch (unilbrk_table [last_prop] [prop])
		    {
		    case D:
		      *q = UC_BREAK_POSSIBLE;
		      break;
		    case I:
		      *q = (seen_space != NULL ? UC_BREAK_POSSIBLE : UC_BREAK_PROHIBITED);
		      break;
		    case P:
		      *q = UC_BREAK_PROHIBITED;
		      break;
		    default:
		      abort ();
		    }
		}
	      last_prop = prop;
	      seen_space = NULL;
	      seen_space2 = NULL;
	    }
	}

      s++;
      p++;
    }
}