fribidi.c

GTK+-2.0源码之pango-1.15.6.tar.gz

  FriBidiLevel base_level, max_level;
  FriBidiCharType base_dir;
  TypeLink *type_rl_list, *explicits_list, *explicits_list_end, *pp;

  DBG ("Entering fribidi_analyse_string()\n");

  /* Determinate character types */
  DBG ("  Determine character types\n");
  {
    FriBidiCharType ored_types;
    FriBidiCharType anded_strongs;

    /* Run length encode the character types */
    type_rl_list = run_length_encode_types_utf8 (str, bytelen, len,
		   				 &ored_types, &anded_strongs);

    /* The case that all resolved levels will be ltr.
     * First, all strongs should be ltr, and one of the following:
     *
     *	o *pbase_dir doesn't have an rtl taste.
     *	o there are letters, and *pbase_dir is weak.
     */
    if (!FRIBIDI_IS_RTL (ored_types) &&
	     (!FRIBIDI_IS_RTL (*pbase_dir) ||
	      (FRIBIDI_IS_WEAK (*pbase_dir) && FRIBIDI_IS_LETTER (ored_types))
	     ))
      {
	/* all ltr */
	free_rl_list (type_rl_list);

	*ptype_rl_list = NULL;
	*pmax_level = 0;
	*pbase_dir = FRIBIDI_TYPE_LTR;

	return 0;
      }
    /* The case that all resolved levels will be rtl is much more complex.
     * First, there should be no numbers, all strongs be rtl, and one of
     * the following:
     *
     *	o *pbase_dir has an rtl taste (may be weak).
     *	o there are letters, and *pbase_dir is weak.
     */
    else if (!FRIBIDI_IS_NUMBER (ored_types) && FRIBIDI_IS_RTL (anded_strongs) &&
	     (FRIBIDI_IS_RTL (*pbase_dir) ||
	      (FRIBIDI_IS_WEAK (*pbase_dir) && FRIBIDI_IS_LETTER (ored_types))
	     ))
      {
	free_rl_list (type_rl_list);

	*ptype_rl_list = NULL;
	*pmax_level = 1;
	*pbase_dir = FRIBIDI_TYPE_RTL;

	return 0;
      }
  }
  DBG ("  Determine character types, Done\n");

  init_list (&explicits_list, &explicits_list_end);

  /* Find base level */
  DBG ("  Finding the base level\n");
  if (FRIBIDI_IS_STRONG (*pbase_dir))
    base_level = FRIBIDI_DIR_TO_LEVEL (*pbase_dir);
  /* P2. P3. Search for first strong character and use its direction as
     base direction */
  else
    {
      /* If no strong base_dir was found, resort to the weak direction
         that was passed on input. */
      base_level = FRIBIDI_DIR_TO_LEVEL (*pbase_dir);
      base_dir = FRIBIDI_TYPE_ON;
      for (pp = type_rl_list; pp; pp = pp->next)
	if (FRIBIDI_IS_LETTER (RL_TYPE (pp)))
	  {
	    base_level = FRIBIDI_DIR_TO_LEVEL (RL_TYPE (pp));
	    base_dir = FRIBIDI_LEVEL_TO_DIR (base_level);
	    break;
	  }
    }
  base_dir = FRIBIDI_LEVEL_TO_DIR (base_level);
  DBG2 ("  Base level : %c\n", fribidi_char_from_level (base_level));
  DBG2 ("  Base dir   : %c\n", fribidi_char_from_type (base_dir));
  DBG ("  Finding the base level, Done\n");

  /* Explicit Levels and Directions */
  DBG ("Explicit Levels and Directions\n");
  {
    /* X1. Begin by setting the current embedding level to the paragraph
       embedding level. Set the directional override status to neutral.
       Process each character iteratively, applying rules X2 through X9.
       Only embedding levels from 0 to 61 are valid in this phase. */
    FriBidiLevel level, new_level;
    FriBidiCharType override, new_override;
    FriBidiStrIndex i;
    int stack_size, over_pushed, first_interval;
    LevelInfo *status_stack;
    TypeLink temp_link;

    level = base_level;
    override = FRIBIDI_TYPE_ON;
    /* stack */
    stack_size = 0;
    over_pushed = 0;
    first_interval = 0;
    status_stack =
      (LevelInfo *) malloc (sizeof (LevelInfo) * (UNI_MAX_BIDI_LEVEL + 2));

    for (pp = type_rl_list->next; pp->next; pp = pp->next)
      {
	FriBidiCharType this_type = RL_TYPE (pp);
	if (FRIBIDI_IS_EXPLICIT_OR_BN (this_type))
	  {
	    if (FRIBIDI_IS_STRONG (this_type))
	      {			/* LRE, RLE, LRO, RLO */
		/* 1. Explicit Embeddings */
		/*   X2. With each RLE, compute the least greater odd embedding level. */
		/*   X3. With each LRE, compute the least greater even embedding level. */
		/* 2. Explicit Overrides */
		/*   X4. With each RLO, compute the least greater odd embedding level. */
		/*   X5. With each LRO, compute the least greater even embedding level. */
		new_override = FRIBIDI_EXPLICIT_TO_OVERRIDE_DIR (this_type);
		for (i = 0; i < RL_LEN (pp); i++)
		  {
		    new_level =
		      ((level + FRIBIDI_DIR_TO_LEVEL (this_type) + 2) & ~1) -
		      FRIBIDI_DIR_TO_LEVEL (this_type);
		    PUSH_STATUS;
		  }
	      }
	    else if (this_type == FRIBIDI_TYPE_PDF)
	      {
		/* 3. Terminating Embeddings and overrides */
		/*   X7. With each PDF, determine the matching embedding or
		   override code. */
		for (i = 0; i < RL_LEN (pp); i++)
		  POP_STATUS;
	      }
	    /* X9. Remove all RLE, LRE, RLO, LRO, PDF, and BN codes. */
	    /* Remove element and add it to explicits_list */
	    temp_link.next = pp->next;
	    pp->level = FRIBIDI_LEVEL_REMOVED;
	    move_element_before (pp, explicits_list_end);
	    pp = &temp_link;
	  }
	else
	  {
	    /* X6. For all typed besides RLE, LRE, RLO, LRO, and PDF:
	       a. Set the level of the current character to the current
	       embedding level.
	       b. Whenever the directional override status is not neutral,
	       reset the current character type to the directional override
	       status. */
	    RL_LEVEL (pp) = level;
	    if (!FRIBIDI_IS_NEUTRAL (override))
	      RL_TYPE (pp) = override;
	  }
	/* X8. All explicit directional embeddings and overrides are
	   completely terminated at the end of each paragraph. Paragraph
	   separators are not included in the embedding. */
	/* This function is running on a single paragraph, so we can do
	   X8 after all the input is processed. */
      }

    /* Implementing X8. It has no effect on a single paragraph! */
    level = base_level;
    override = FRIBIDI_TYPE_ON;
    stack_size = 0;
    over_pushed = 0;

    free (status_stack);
  }
  /* X10. The remaining rules are applied to each run of characters at the
     same level. For each run, determine the start-of-level-run (sor) and
     end-of-level-run (eor) type, either L or R. This depends on the
     higher of the two levels on either side of the boundary (at the start
     or end of the paragraph, the level of the 'other' run is the base
     embedding level). If the higher level is odd, the type is R, otherwise
     it is L. */
  /* Resolving Implicit Levels can be done out of X10 loop, so only change
     of Resolving Weak Types and Resolving Neutral Types is needed. */

  compact_list (type_rl_list);

  /* 4. Resolving weak types */
  DBG ("Resolving weak types\n");
  {
    FriBidiCharType last_strong, prev_type_org;
    fribidi_boolean w4;

    last_strong = base_dir;

    for (pp = type_rl_list->next; pp->next; pp = pp->next)
      {
	FriBidiCharType prev_type, this_type, next_type;

	prev_type = PREV_TYPE_OR_SOR (pp);
	this_type = RL_TYPE (pp);
	next_type = NEXT_TYPE_OR_EOR (pp);

	if (FRIBIDI_IS_STRONG (prev_type))
	  last_strong = prev_type;

	/* W1. NSM
	   Examine each non-spacing mark (NSM) in the level run, and change the
	   type of the NSM to the type of the previous character. If the NSM
	   is at the start of the level run, it will get the type of sor. */
	/* Implementation note: it is important that if the previous character
	   is not sor, then we should merge this run with the previous,
	   because of rules like W5, that we assume all of a sequence of
	   adjacent ETs are in one TypeLink. */
	if (this_type == FRIBIDI_TYPE_NSM)
	  {
	    if (RL_LEVEL (pp->prev) == RL_LEVEL (pp))
	      pp = merge_with_prev (pp);
	    else
	      RL_TYPE (pp) = prev_type;
	    continue;		/* As we know the next condition cannot be true. */
	  }

	/* W2: European numbers. */
	if (this_type == FRIBIDI_TYPE_EN && last_strong == FRIBIDI_TYPE_AL)
	  {
	    RL_TYPE (pp) = FRIBIDI_TYPE_AN;

	    /* Resolving dependency of loops for rules W1 and W2, so we
	       can merge them in one loop. */
	    if (next_type == FRIBIDI_TYPE_NSM)
	      RL_TYPE (pp->next) = FRIBIDI_TYPE_AN;
	  }
      }


    last_strong = base_dir;
    /* Resolving dependency of loops for rules W4 and W5, W5 may
       want to prevent W4 to take effect in the next turn, do this 
       through "w4". */
    w4 = FRIBIDI_TRUE;
    /* Resolving dependency of loops for rules W4 and W5 with W7,
       W7 may change an EN to L but it sets the prev_type_org if needed,
       so W4 and W5 in next turn can still do their works. */
    prev_type_org = FRIBIDI_TYPE_ON;

    for (pp = type_rl_list->next; pp->next; pp = pp->next)
      {
	FriBidiCharType prev_type, this_type, next_type;

	prev_type = PREV_TYPE_OR_SOR (pp);
	this_type = RL_TYPE (pp);
	next_type = NEXT_TYPE_OR_EOR (pp);

	if (FRIBIDI_IS_STRONG (prev_type))
	  last_strong = prev_type;

	/* W3: Change ALs to R. */
	if (this_type == FRIBIDI_TYPE_AL)
	  {
	    RL_TYPE (pp) = FRIBIDI_TYPE_RTL;
	    w4 = FRIBIDI_TRUE;
	    prev_type_org = FRIBIDI_TYPE_ON;
	    continue;
	  }

	/* W4. A single european separator changes to a european number.
	   A single common separator between two numbers of the same type
	   changes to that type. */
	if (w4
	    && RL_LEN (pp) == 1 && FRIBIDI_IS_ES_OR_CS (this_type)
	    && FRIBIDI_IS_NUMBER (prev_type_org) && prev_type_org == next_type
	    && (prev_type_org == FRIBIDI_TYPE_EN
		|| this_type == FRIBIDI_TYPE_CS))
	  {
	    RL_TYPE (pp) = prev_type;
	    this_type = RL_TYPE (pp);
	  }
	w4 = FRIBIDI_TRUE;

	/* W5. A sequence of European terminators adjacent to European
	   numbers changes to All European numbers. */
	if (this_type == FRIBIDI_TYPE_ET
	    && (prev_type_org == FRIBIDI_TYPE_EN
		|| next_type == FRIBIDI_TYPE_EN))
	  {
	    RL_TYPE (pp) = FRIBIDI_TYPE_EN;
	    w4 = FRIBIDI_FALSE;
	    this_type = RL_TYPE (pp);
	  }

	/* W6. Otherwise change separators and terminators to other neutral. */
	if (FRIBIDI_IS_NUMBER_SEPARATOR_OR_TERMINATOR (this_type))
	  RL_TYPE (pp) = FRIBIDI_TYPE_ON;

	/* W7. Change european numbers to L. */
	if (this_type == FRIBIDI_TYPE_EN && last_strong == FRIBIDI_TYPE_LTR)
	  {
	    RL_TYPE (pp) = FRIBIDI_TYPE_LTR;
	    prev_type_org = (RL_LEVEL (pp) == RL_LEVEL (pp->next) ?
			     FRIBIDI_TYPE_EN : FRIBIDI_TYPE_ON);
	  }
	else
	  prev_type_org = PREV_TYPE_OR_SOR (pp->next);
      }
  }

  compact_neutrals (type_rl_list);

  /* 5. Resolving Neutral Types */
  DBG ("Resolving neutral types\n");
  {
    /* N1. and N2.
       For each neutral, resolve it. */
    for (pp = type_rl_list->next; pp->next; pp = pp->next)
      {
	FriBidiCharType prev_type, this_type, next_type;

	/* "European and arabic numbers are treated as though they were R"
	   FRIBIDI_CHANGE_NUMBER_TO_RTL does this. */
	this_type = FRIBIDI_CHANGE_NUMBER_TO_RTL (RL_TYPE (pp));
	prev_type = FRIBIDI_CHANGE_NUMBER_TO_RTL (PREV_TYPE_OR_SOR (pp));
	next_type = FRIBIDI_CHANGE_NUMBER_TO_RTL (NEXT_TYPE_OR_EOR (pp));

	if (FRIBIDI_IS_NEUTRAL (this_type))
	  RL_TYPE (pp) = (prev_type == next_type) ?
	    /* N1. */ prev_type :
	    /* N2. */ FRIBIDI_EMBEDDING_DIRECTION (pp);
      }
  }

  compact_list (type_rl_list);

  /* 6. Resolving implicit levels */
  DBG ("Resolving implicit levels\n");
  {
    max_level = base_level;

    for (pp = type_rl_list->next; pp->next; pp = pp->next)
      {
	FriBidiCharType this_type;
	int level;

	this_type = RL_TYPE (pp);
	level = RL_LEVEL (pp);

	/* I1. Even */
	/* I2. Odd */
	if (FRIBIDI_IS_NUMBER (this_type))
	  RL_LEVEL (pp) = (level + 2) & ~1;
	else
	  RL_LEVEL (pp) = (level ^ FRIBIDI_DIR_TO_LEVEL (this_type)) +
	    (level & 1);

	if (RL_LEVEL (pp) > max_level)
	  max_level = RL_LEVEL (pp);
      }
  }

  compact_list (type_rl_list);

/* Reinsert the explicit codes & bn's that already removed, from the
   explicits_list to type_rl_list. */
  DBG ("Reinserting explicit codes\n");
  {
    TypeLink *p;

    override_list (type_rl_list, explicits_list);
    p = type_rl_list->next;
    if (p->level < 0)
      p->level = base_level;
    for (; p->next; p = p->next)
      if (p->level < 0)
	p->level = p->prev->level;
  }

  DBG ("Reset the embedding levels\n");
  {
    int j, k, state, pos;
    TypeLink *p, *q, *list, *list_end;

    const char *strp = str + bytelen;

    /* L1. Reset the embedding levels of some chars. */
    init_list (&list, &list_end);
    q = list_end;
    state = 1;
    pos = *len - 1;
    for (j = *len - 1; j >= -1; j--)
      {
	/* if state is on at the very first of string, do this too. */
	if (j >= 0)
	  k = fribidi_get_type (g_utf8_get_char (strp = g_utf8_prev_char (strp)));
	else
	  k = FRIBIDI_TYPE_ON;
	if (!state && FRIBIDI_IS_SEPARATOR (k))
	  {
	    state = 1;
	    pos = j;
	  }
	else if (state && !FRIBIDI_IS_EXPLICIT_OR_SEPARATOR_OR_BN_OR_WS (k))
	  {
	    state = 0;
	    p = new_type_link ();
	    p->prev = p->next = NULL;
	    p->pos = j + 1;
	    p->len = pos - j;
	    p->type = base_dir;
	    p->level = base_level;
	    move_element_before (p, q);
	    q = p;
	  }
      }
    override_list (type_rl_list, list);
  }

  *ptype_rl_list = type_rl_list;
  *pmax_level = max_level;
  *pbase_dir = base_dir;

  DBG ("Leaving fribidi_analyse_string()\n");
  return 1;
}

/*======================================================================
 *  fribidi_log2vis_get_embedding_levels() is used in order to just get
 *  the embedding levels.
 *----------------------------------------------------------------------*/
FRIBIDI_API FriBidiLevel *
fribidi_log2vis_get_embedding_levels_new_utf8 (	/* input */
				       const char *str,
				       int bytelen,
				       FriBidiCharType *pbase_dir)
{
  TypeLink *type_rl_list, *pp;
  FriBidiLevel max_level, *embedding_level_list;
  FriBidiStrIndex len;

  DBG ("Entering fribidi_log2vis_get_embedding_levels()\n");

  if (bytelen == 0)
    {
      DBG ("Leaving fribidi_log2vis_get_embedding_levels()\n");
      return NULL;
    }

  if (!fribidi_analyse_string_utf8 (str, bytelen, pbase_dir,
			  /* output */
			  &len, &type_rl_list, &max_level))
    {
     /* unidirectional.  return all-zero or all-one embedding levels */

     if (max_level)
       {
         embedding_level_list = g_new (FriBidiLevel, len);
	 /* assumes sizeof(FriBidiLevel) == 1, which is true! */
	 memset (embedding_level_list, max_level, len);
	 return embedding_level_list;
       }
     else
       {
         return g_new0 (FriBidiLevel, len);
       }
    }

  embedding_level_list = g_new (FriBidiLevel, len);
  for (pp = type_rl_list->next; pp->next; pp = pp->next)
    {
      FriBidiStrIndex i, pos = RL_POS (pp), len = RL_LEN (pp);
      FriBidiLevel level = RL_LEVEL (pp);
      for (i = 0; i < len; i++)
	embedding_level_list[pos + i] = level;
    }

  free_rl_list (type_rl_list);

  DBG ("Leaving fribidi_log2vis_get_embedding_levels()\n");
  return embedding_level_list;
}