/* FriBidi

 * fribidi-joining.h - Arabic joining algorithm

 *

 * Authors:

 *   Behdad Esfahbod, 2004

 *

 * Copyright (C) 2004 Sharif FarsiWeb, Inc

 * Copyright (C) 2004 Behdad Esfahbod

 * 

 * This library 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 2.1 of the License, or (at your option) any later version.

 * 

 * This library 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 library, in a file named COPYING; if not, write to the

 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,

 * Boston, MA 02110-1301, USA

 * 

 * For licensing issues, contact <fribidi.license@gmail.com>.

 */

#include "common.h"

#include <fribidi-joining.h>

#include "bidi-types.h"

#include "joining-types.h"

#ifdef DEBUG

/*======================================================================

 *  For debugging, define some functions for printing joining types and

 *  properties.

 *----------------------------------------------------------------------*/

static void

print_joining_types (

  /* input */

  const FriBidiLevel *embedding_levels,

  const FriBidiStrIndex len,

  const FriBidiJoiningType *jtypes

)

{

  register FriBidiStrIndex i;

  fribidi_assert (jtypes);

  MSG ("  Join. types: ");

  for (i = 0; i < len; i++)

    MSG2 ("%c", fribidi_char_from_joining_type (jtypes[i],

            !FRIBIDI_LEVEL_IS_RTL

            (embedding_levels[i])));

  MSG ("\n");

}

#endif /* DEBUG */

#define FRIBIDI_CONSISTENT_LEVEL(i) \

  (FRIBIDI_IS_EXPLICIT_OR_BN (bidi_types[(i)])  \

   ? FRIBIDI_SENTINEL  \

   : embedding_levels[(i)])

#define FRIBIDI_LEVELS_MATCH(i, j)  \

  ((i) == (j) || (i) == FRIBIDI_SENTINEL || (j) == FRIBIDI_SENTINEL)

FRIBIDI_ENTRY void

fribidi_join_arabic (

  /* input */

  const FriBidiCharType *bidi_types,

  const FriBidiStrIndex len,

  const FriBidiLevel *embedding_levels,

  /* input and output */

  FriBidiArabicProp *ar_props

)

{

  if UNLIKELY

    (len == 0) return;

  DBG ("in fribidi_join_arabic");

  fribidi_assert (bidi_types);

  fribidi_assert (embedding_levels);

  fribidi_assert (ar_props);

# if DEBUG

  if UNLIKELY

    (fribidi_debug_status ())

    {

      print_joining_types (embedding_levels, len, ar_props);

    }

# endif /* DEBUG */

  /* The joining algorithm turned out very very dirty :(.  That's what happens

   * when you follow the standard which has never been implemented closely

   * before.

   */

  /* 8.2 Arabic - Cursive Joining */

  DBG ("Arabic cursive joining");

  {

    /* The following do not need to be initialized as long as joins is

     * initialized to false.  We just do to turn off compiler warnings. */

    register FriBidiStrIndex saved = 0;

    register FriBidiLevel saved_level = FRIBIDI_SENTINEL;

    register fribidi_boolean saved_shapes = false;

    register FriBidiArabicProp saved_joins_following_mask = 0;

    register fribidi_boolean joins = false;

    register FriBidiStrIndex i;

    for (i = 0; i < len; i++)

      if (!FRIBIDI_IS_JOINING_TYPE_G (ar_props[i]))

  {

    register fribidi_boolean disjoin = false;

    register fribidi_boolean shapes = FRIBIDI_ARAB_SHAPES (ar_props[i]);

    register FriBidiLevel level = FRIBIDI_CONSISTENT_LEVEL (i);

    if (joins && !FRIBIDI_LEVELS_MATCH (saved_level, level))

      {

        disjoin = true;

        joins = false;

      }

    if (!FRIBIDI_IS_JOIN_SKIPPED (ar_props[i]))

      {

        register const FriBidiArabicProp joins_preceding_mask =

    FRIBIDI_JOINS_PRECEDING_MASK (level);

        if (!joins)

    {

      if (shapes)

        FRIBIDI_UNSET_BITS (ar_props[i], joins_preceding_mask);

    }

        else if (!FRIBIDI_TEST_BITS (ar_props[i], joins_preceding_mask))

          {

      disjoin = true;

    }

        else

          {

      register FriBidiStrIndex j;

      /* This is a FriBidi extension:  we set joining properties

       * for skipped characters in between, so we can put NSMs on tatweel

       * later if we want.  Useful on console for example.

       */

      for (j = saved + 1; j < i; j++)

        FRIBIDI_SET_BITS (ar_props[j], joins_preceding_mask | saved_joins_following_mask);

    }

      }

    if (disjoin && saved_shapes)

      FRIBIDI_UNSET_BITS (ar_props[saved], saved_joins_following_mask);

    if (!FRIBIDI_IS_JOIN_SKIPPED (ar_props[i]))

      {

        saved = i;

        saved_level = level;

        saved_shapes = shapes;

        saved_joins_following_mask =

    FRIBIDI_JOINS_FOLLOWING_MASK (level);

        joins =

    FRIBIDI_TEST_BITS (ar_props[i], saved_joins_following_mask);

      }

  }

    if ((joins) && saved_shapes)

      FRIBIDI_UNSET_BITS (ar_props[saved], saved_joins_following_mask);

  }

# if DEBUG

  if UNLIKELY

    (fribidi_debug_status ())

    {

      print_joining_types (embedding_levels, len, ar_props);

    }

# endif /* DEBUG */

  DBG ("leaving fribidi_join_arabic");

}

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