bidi.c 63.3 KB
Newer Older
Eli Zaretskii's avatar
Eli Zaretskii committed
1
/* Low-level bidirectional buffer-scanning functions for GNU Emacs.
2
   Copyright (C) 2000, 2001, 2004, 2005, 2009	Free Software Foundation, Inc.
Eli Zaretskii's avatar
Eli Zaretskii committed
3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

This file is part of GNU Emacs.

GNU Emacs is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Emacs 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 General Public License for more details.


You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.  */

22 23 24
/* Written by Eli Zaretskii <eliz@gnu.org>.

   A sequential implementation of the Unicode Bidirectional algorithm,
Eli Zaretskii's avatar
Eli Zaretskii committed
25 26 27 28 29 30 31 32 33 34 35 36 37 38
   as per UAX#9, a part of the Unicode Standard.

   Unlike the reference and most other implementations, this one is
   designed to be called once for every character in the buffer.

   The main entry point is bidi_get_next_char_visually.  Each time it
   is called, it finds the next character in the visual order, and
   returns its information in a special structure.  The caller is then
   expected to process this character for display or any other
   purposes, and call bidi_get_next_char_visually for the next
   character.  See the comments in bidi_get_next_char_visually for
   more details about its algorithm that finds the next visual-order
   character by resolving their levels on the fly.

39 40 41 42
   If you want to understand the code, you will have to read it
   together with the relevant portions of UAX#9.  The comments include
   references to UAX#9 rules, for that very reason.

Eli Zaretskii's avatar
Eli Zaretskii committed
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57
   A note about references to UAX#9 rules: if the reference says
   something like "X9/Retaining", it means that you need to refer to
   rule X9 and to its modifications decribed in the "Implementation
   Notes" section of UAX#9, under "Retaining Format Codes".  */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>

#ifdef HAVE_STRING_H
#include <string.h>
#endif

58 59
#include <setjmp.h>

Eli Zaretskii's avatar
Eli Zaretskii committed
60 61 62 63 64 65 66 67 68
#include "lisp.h"
#include "buffer.h"
#include "character.h"
#include "dispextern.h"

static int bidi_initialized = 0;

static Lisp_Object bidi_type_table;

69
/* FIXME: Remove these when bidi_explicit_dir_char uses a lookup table.  */
Eli Zaretskii's avatar
Eli Zaretskii committed
70 71 72 73 74 75 76 77 78
#define LRM_CHAR   0x200E
#define RLM_CHAR   0x200F
#define LRE_CHAR   0x202A
#define RLE_CHAR   0x202B
#define PDF_CHAR   0x202C
#define LRO_CHAR   0x202D
#define RLO_CHAR   0x202E

#define BIDI_EOB   -1
79
#define BIDI_BOB   -2		/* FIXME: Is this needed? */
Eli Zaretskii's avatar
Eli Zaretskii committed
80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100

/* Local data structures.  (Look in dispextern.h for the rest.)  */

/* What we need to know about the current paragraph.  */
struct bidi_paragraph_info {
  int start_bytepos;	/* byte position where it begins */
  int end_bytepos;	/* byte position where it ends */
  int embedding_level;	/* its basic embedding level */
  bidi_dir_t base_dir;	/* its base direction */
};

/* Data type for describing the bidirectional character categories.  */
typedef enum {
  UNKNOWN_BC,
  NEUTRAL,
  WEAK,
  STRONG
} bidi_category_t;

int bidi_ignore_explicit_marks_for_paragraph_level = 1;

101 102
static Lisp_Object fallback_paragraph_start_re, fallback_paragraph_separate_re;
static Lisp_Object Qparagraph_start, Qparagraph_separate;
Eli Zaretskii's avatar
Eli Zaretskii committed
103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124

static void
bidi_initialize ()
{
  /* FIXME: This should come from the Unicode Database.  */
  struct {
    int from, to;
    bidi_type_t type;
  } bidi_type[] =
      { { 0x0000, 0x0008, WEAK_BN },
	{ 0x0009, 0x0000, NEUTRAL_S },
	{ 0x000A, 0x0000, NEUTRAL_B },
	{ 0x000B, 0x0000, NEUTRAL_S },
	{ 0x000C, 0x0000, NEUTRAL_WS },
	{ 0x000D, 0x0000, NEUTRAL_B },
	{ 0x000E, 0x001B, WEAK_BN },
	{ 0x001C, 0x001E, NEUTRAL_B },
	{ 0x001F, 0x0000, NEUTRAL_S },
	{ 0x0020, 0x0000, NEUTRAL_WS },
	{ 0x0021, 0x0022, NEUTRAL_ON },
	{ 0x0023, 0x0025, WEAK_ET },
	{ 0x0026, 0x002A, NEUTRAL_ON },
125
	{ 0x002B, 0x0000, WEAK_ES },
Eli Zaretskii's avatar
Eli Zaretskii committed
126
	{ 0x002C, 0x0000, WEAK_CS },
127 128
	{ 0x002D, 0x0000, WEAK_ES },
	{ 0x002E, 0x002F, WEAK_CS },
Eli Zaretskii's avatar
Eli Zaretskii committed
129 130 131 132 133 134 135 136 137 138 139 140
	{ 0x0030, 0x0039, WEAK_EN },
	{ 0x003A, 0x0000, WEAK_CS },
	{ 0x003B, 0x0040, NEUTRAL_ON },
	{ 0x005B, 0x0060, NEUTRAL_ON },
	{ 0x007B, 0x007E, NEUTRAL_ON },
	{ 0x007F, 0x0084, WEAK_BN },
	{ 0x0085, 0x0000, NEUTRAL_B },
	{ 0x0086, 0x009F, WEAK_BN },
	{ 0x00A0, 0x0000, WEAK_CS },
	{ 0x00A1, 0x0000, NEUTRAL_ON },
	{ 0x00A2, 0x00A5, WEAK_ET },
	{ 0x00A6, 0x00A9, NEUTRAL_ON },
141 142 143
	{ 0x00AB, 0x00AC, NEUTRAL_ON },
	{ 0x00AD, 0x0000, WEAK_BN },
	{ 0x00AE, 0x00Af, NEUTRAL_ON },
Eli Zaretskii's avatar
Eli Zaretskii committed
144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168
	{ 0x00B0, 0x00B1, WEAK_ET },
	{ 0x00B2, 0x00B3, WEAK_EN },
	{ 0x00B4, 0x0000, NEUTRAL_ON },
	{ 0x00B6, 0x00B8, NEUTRAL_ON },
	{ 0x00B9, 0x0000, WEAK_EN },
	{ 0x00BB, 0x00BF, NEUTRAL_ON },
	{ 0x00D7, 0x0000, NEUTRAL_ON },
	{ 0x00F7, 0x0000, NEUTRAL_ON },
	{ 0x02B9, 0x02BA, NEUTRAL_ON },
	{ 0x02C2, 0x02CF, NEUTRAL_ON },
	{ 0x02D2, 0x02DF, NEUTRAL_ON },
	{ 0x02E5, 0x02ED, NEUTRAL_ON },
	{ 0x0300, 0x036F, WEAK_NSM },
	{ 0x0374, 0x0375, NEUTRAL_ON },
	{ 0x037E, 0x0385, NEUTRAL_ON },
	{ 0x0387, 0x0000, NEUTRAL_ON },
	{ 0x03F6, 0x0000, NEUTRAL_ON },
	{ 0x0483, 0x0489, WEAK_NSM },
	{ 0x058A, 0x0000, NEUTRAL_ON },
	{ 0x0591, 0x05BD, WEAK_NSM },
	{ 0x05BE, 0x0000, STRONG_R },
	{ 0x05BF, 0x0000, WEAK_NSM },
	{ 0x05C0, 0x0000, STRONG_R },
	{ 0x05C1, 0x05C2, WEAK_NSM },
	{ 0x05C3, 0x0000, STRONG_R },
169 170 171
	{ 0x05C4, 0x05C5, WEAK_NSM },
	{ 0x05C6, 0x0000, STRONG_R },
	{ 0x05C7, 0x0000, WEAK_NSM },
Eli Zaretskii's avatar
Eli Zaretskii committed
172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390
	{ 0x05D0, 0x05F4, STRONG_R },
	{ 0x060C, 0x0000, WEAK_CS },
	{ 0x061B, 0x064A, STRONG_AL },
	{ 0x064B, 0x0655, WEAK_NSM },
	{ 0x0660, 0x0669, WEAK_AN },
	{ 0x066A, 0x0000, WEAK_ET },
	{ 0x066B, 0x066C, WEAK_AN },
	{ 0x066D, 0x066F, STRONG_AL },
	{ 0x0670, 0x0000, WEAK_NSM },
	{ 0x0671, 0x06D5, STRONG_AL },
	{ 0x06D6, 0x06DC, WEAK_NSM },
	{ 0x06DD, 0x0000, STRONG_AL },
	{ 0x06DE, 0x06E4, WEAK_NSM },
	{ 0x06E5, 0x06E6, STRONG_AL },
	{ 0x06E7, 0x06E8, WEAK_NSM },
	{ 0x06E9, 0x0000, NEUTRAL_ON },
	{ 0x06EA, 0x06ED, WEAK_NSM },
	{ 0x06F0, 0x06F9, WEAK_EN },
	{ 0x06FA, 0x070D, STRONG_AL },
	{ 0x070F, 0x0000, WEAK_BN },
	{ 0x0710, 0x0000, STRONG_AL },
	{ 0x0711, 0x0000, WEAK_NSM },
	{ 0x0712, 0x072C, STRONG_AL },
	{ 0x0730, 0x074A, WEAK_NSM },
	{ 0x0780, 0x07A5, STRONG_AL },
	{ 0x07A6, 0x07B0, WEAK_NSM },
	{ 0x07B1, 0x0000, STRONG_AL },
	{ 0x0901, 0x0902, WEAK_NSM },
	{ 0x093C, 0x0000, WEAK_NSM },
	{ 0x0941, 0x0948, WEAK_NSM },
	{ 0x094D, 0x0000, WEAK_NSM },
	{ 0x0951, 0x0954, WEAK_NSM },
	{ 0x0962, 0x0963, WEAK_NSM },
	{ 0x0981, 0x0000, WEAK_NSM },
	{ 0x09BC, 0x0000, WEAK_NSM },
	{ 0x09C1, 0x09C4, WEAK_NSM },
	{ 0x09CD, 0x0000, WEAK_NSM },
	{ 0x09E2, 0x09E3, WEAK_NSM },
	{ 0x09F2, 0x09F3, WEAK_ET },
	{ 0x0A02, 0x0000, WEAK_NSM },
	{ 0x0A3C, 0x0000, WEAK_NSM },
	{ 0x0A41, 0x0A4D, WEAK_NSM },
	{ 0x0A70, 0x0A71, WEAK_NSM },
	{ 0x0A81, 0x0A82, WEAK_NSM },
	{ 0x0ABC, 0x0000, WEAK_NSM },
	{ 0x0AC1, 0x0AC8, WEAK_NSM },
	{ 0x0ACD, 0x0000, WEAK_NSM },
	{ 0x0B01, 0x0000, WEAK_NSM },
	{ 0x0B3C, 0x0000, WEAK_NSM },
	{ 0x0B3F, 0x0000, WEAK_NSM },
	{ 0x0B41, 0x0B43, WEAK_NSM },
	{ 0x0B4D, 0x0B56, WEAK_NSM },
	{ 0x0B82, 0x0000, WEAK_NSM },
	{ 0x0BC0, 0x0000, WEAK_NSM },
	{ 0x0BCD, 0x0000, WEAK_NSM },
	{ 0x0C3E, 0x0C40, WEAK_NSM },
	{ 0x0C46, 0x0C56, WEAK_NSM },
	{ 0x0CBF, 0x0000, WEAK_NSM },
	{ 0x0CC6, 0x0000, WEAK_NSM },
	{ 0x0CCC, 0x0CCD, WEAK_NSM },
	{ 0x0D41, 0x0D43, WEAK_NSM },
	{ 0x0D4D, 0x0000, WEAK_NSM },
	{ 0x0DCA, 0x0000, WEAK_NSM },
	{ 0x0DD2, 0x0DD6, WEAK_NSM },
	{ 0x0E31, 0x0000, WEAK_NSM },
	{ 0x0E34, 0x0E3A, WEAK_NSM },
	{ 0x0E3F, 0x0000, WEAK_ET },
	{ 0x0E47, 0x0E4E, WEAK_NSM },
	{ 0x0EB1, 0x0000, WEAK_NSM },
	{ 0x0EB4, 0x0EBC, WEAK_NSM },
	{ 0x0EC8, 0x0ECD, WEAK_NSM },
	{ 0x0F18, 0x0F19, WEAK_NSM },
	{ 0x0F35, 0x0000, WEAK_NSM },
	{ 0x0F37, 0x0000, WEAK_NSM },
	{ 0x0F39, 0x0000, WEAK_NSM },
	{ 0x0F3A, 0x0F3D, NEUTRAL_ON },
	{ 0x0F71, 0x0F7E, WEAK_NSM },
	{ 0x0F80, 0x0F84, WEAK_NSM },
	{ 0x0F86, 0x0F87, WEAK_NSM },
	{ 0x0F90, 0x0FBC, WEAK_NSM },
	{ 0x0FC6, 0x0000, WEAK_NSM },
	{ 0x102D, 0x1030, WEAK_NSM },
	{ 0x1032, 0x1037, WEAK_NSM },
	{ 0x1039, 0x0000, WEAK_NSM },
	{ 0x1058, 0x1059, WEAK_NSM },
	{ 0x1680, 0x0000, NEUTRAL_WS },
	{ 0x169B, 0x169C, NEUTRAL_ON },
	{ 0x1712, 0x1714, WEAK_NSM },
	{ 0x1732, 0x1734, WEAK_NSM },
	{ 0x1752, 0x1753, WEAK_NSM },
	{ 0x1772, 0x1773, WEAK_NSM },
	{ 0x17B7, 0x17BD, WEAK_NSM },
	{ 0x17C6, 0x0000, WEAK_NSM },
	{ 0x17C9, 0x17D3, WEAK_NSM },
	{ 0x17DB, 0x0000, WEAK_ET },
	{ 0x1800, 0x180A, NEUTRAL_ON },
	{ 0x180B, 0x180D, WEAK_NSM },
	{ 0x180E, 0x0000, WEAK_BN },
	{ 0x18A9, 0x0000, WEAK_NSM },
	{ 0x1FBD, 0x0000, NEUTRAL_ON },
	{ 0x1FBF, 0x1FC1, NEUTRAL_ON },
	{ 0x1FCD, 0x1FCF, NEUTRAL_ON },
	{ 0x1FDD, 0x1FDF, NEUTRAL_ON },
	{ 0x1FED, 0x1FEF, NEUTRAL_ON },
	{ 0x1FFD, 0x1FFE, NEUTRAL_ON },
	{ 0x2000, 0x200A, NEUTRAL_WS },
	{ 0x200B, 0x200D, WEAK_BN },
	{ 0x200F, 0x0000, STRONG_R },
	{ 0x2010, 0x2027, NEUTRAL_ON },
	{ 0x2028, 0x0000, NEUTRAL_WS },
	{ 0x2029, 0x0000, NEUTRAL_B },
	{ 0x202A, 0x0000, LRE },
	{ 0x202B, 0x0000, RLE },
	{ 0x202C, 0x0000, PDF },
	{ 0x202D, 0x0000, LRO },
	{ 0x202E, 0x0000, RLO },
	{ 0x202F, 0x0000, NEUTRAL_WS },
	{ 0x2030, 0x2034, WEAK_ET },
	{ 0x2035, 0x2057, NEUTRAL_ON },
	{ 0x205F, 0x0000, NEUTRAL_WS },
	{ 0x2060, 0x206F, WEAK_BN },
	{ 0x2070, 0x0000, WEAK_EN },
	{ 0x2074, 0x2079, WEAK_EN },
	{ 0x207A, 0x207B, WEAK_ET },
	{ 0x207C, 0x207E, NEUTRAL_ON },
	{ 0x2080, 0x2089, WEAK_EN },
	{ 0x208A, 0x208B, WEAK_ET },
	{ 0x208C, 0x208E, NEUTRAL_ON },
	{ 0x20A0, 0x20B1, WEAK_ET },
	{ 0x20D0, 0x20EA, WEAK_NSM },
	{ 0x2100, 0x2101, NEUTRAL_ON },
	{ 0x2103, 0x2106, NEUTRAL_ON },
	{ 0x2108, 0x2109, NEUTRAL_ON },
	{ 0x2114, 0x0000, NEUTRAL_ON },
	{ 0x2116, 0x2118, NEUTRAL_ON },
	{ 0x211E, 0x2123, NEUTRAL_ON },
	{ 0x2125, 0x0000, NEUTRAL_ON },
	{ 0x2127, 0x0000, NEUTRAL_ON },
	{ 0x2129, 0x0000, NEUTRAL_ON },
	{ 0x212E, 0x0000, WEAK_ET },
	{ 0x2132, 0x0000, NEUTRAL_ON },
	{ 0x213A, 0x0000, NEUTRAL_ON },
	{ 0x2140, 0x2144, NEUTRAL_ON },
	{ 0x214A, 0x215F, NEUTRAL_ON },
	{ 0x2190, 0x2211, NEUTRAL_ON },
	{ 0x2212, 0x2213, WEAK_ET },
	{ 0x2214, 0x2335, NEUTRAL_ON },
	{ 0x237B, 0x2394, NEUTRAL_ON },
	{ 0x2396, 0x244A, NEUTRAL_ON },
	{ 0x2460, 0x249B, WEAK_EN },
	{ 0x24EA, 0x0000, WEAK_EN },
	{ 0x24EB, 0x2FFB, NEUTRAL_ON },
	{ 0x3000, 0x0000, NEUTRAL_WS },
	{ 0x3001, 0x3004, NEUTRAL_ON },
	{ 0x3008, 0x3020, NEUTRAL_ON },
	{ 0x302A, 0x302F, WEAK_NSM },
	{ 0x3030, 0x0000, NEUTRAL_ON },
	{ 0x3036, 0x3037, NEUTRAL_ON },
	{ 0x303D, 0x303F, NEUTRAL_ON },
	{ 0x3099, 0x309A, WEAK_NSM },
	{ 0x309B, 0x309C, NEUTRAL_ON },
	{ 0x30A0, 0x0000, NEUTRAL_ON },
	{ 0x30FB, 0x0000, NEUTRAL_ON },
	{ 0x3251, 0x325F, NEUTRAL_ON },
	{ 0x32B1, 0x32BF, NEUTRAL_ON },
	{ 0xA490, 0xA4C6, NEUTRAL_ON },
	{ 0xFB1D, 0x0000, STRONG_R },
	{ 0xFB1E, 0x0000, WEAK_NSM },
	{ 0xFB1F, 0xFB28, STRONG_R },
	{ 0xFB29, 0x0000, WEAK_ET },
	{ 0xFB2A, 0xFB4F, STRONG_R },
	{ 0xFB50, 0xFD3D, STRONG_AL },
	{ 0xFD3E, 0xFD3F, NEUTRAL_ON },
	{ 0xFD50, 0xFDFC, STRONG_AL },
	{ 0xFE00, 0xFE23, WEAK_NSM },
	{ 0xFE30, 0xFE4F, NEUTRAL_ON },
	{ 0xFE50, 0x0000, WEAK_CS },
	{ 0xFE51, 0x0000, NEUTRAL_ON },
	{ 0xFE52, 0x0000, WEAK_CS },
	{ 0xFE54, 0x0000, NEUTRAL_ON },
	{ 0xFE55, 0x0000, WEAK_CS },
	{ 0xFE56, 0xFE5E, NEUTRAL_ON },
	{ 0xFE5F, 0x0000, WEAK_ET },
	{ 0xFE60, 0xFE61, NEUTRAL_ON },
	{ 0xFE62, 0xFE63, WEAK_ET },
	{ 0xFE64, 0xFE68, NEUTRAL_ON },
	{ 0xFE69, 0xFE6A, WEAK_ET },
	{ 0xFE6B, 0x0000, NEUTRAL_ON },
	{ 0xFE70, 0xFEFC, STRONG_AL },
	{ 0xFEFF, 0x0000, WEAK_BN },
	{ 0xFF01, 0xFF02, NEUTRAL_ON },
	{ 0xFF03, 0xFF05, WEAK_ET },
	{ 0xFF06, 0xFF0A, NEUTRAL_ON },
	{ 0xFF0B, 0x0000, WEAK_ET },
	{ 0xFF0C, 0x0000, WEAK_CS },
	{ 0xFF0D, 0x0000, WEAK_ET },
	{ 0xFF0E, 0x0000, WEAK_CS },
	{ 0xFF0F, 0x0000, WEAK_ES },
	{ 0xFF10, 0xFF19, WEAK_EN },
	{ 0xFF1A, 0x0000, WEAK_CS },
	{ 0xFF1B, 0xFF20, NEUTRAL_ON },
	{ 0xFF3B, 0xFF40, NEUTRAL_ON },
	{ 0xFF5B, 0xFF65, NEUTRAL_ON },
	{ 0xFFE0, 0xFFE1, WEAK_ET },
	{ 0xFFE2, 0xFFE4, NEUTRAL_ON },
	{ 0xFFE5, 0xFFE6, WEAK_ET },
	{ 0xFFE8, 0xFFEE, NEUTRAL_ON },
	{ 0xFFF9, 0xFFFB, WEAK_BN },
	{ 0xFFFC, 0xFFFD, NEUTRAL_ON },
	{ 0x1D167, 0x1D169, WEAK_NSM },
	{ 0x1D173, 0x1D17A, WEAK_BN },
	{ 0x1D17B, 0x1D182, WEAK_NSM },
	{ 0x1D185, 0x1D18B, WEAK_NSM },
	{ 0x1D1AA, 0x1D1AD, WEAK_NSM },
	{ 0x1D7CE, 0x1D7FF, WEAK_EN },
	{ 0xE0001, 0xE007F, WEAK_BN } };
  int i;

  bidi_type_table = Fmake_char_table (Qnil, make_number (STRONG_L));
391
  staticpro (&bidi_type_table);
Eli Zaretskii's avatar
Eli Zaretskii committed
392 393

  for (i = 0; i < sizeof bidi_type / sizeof bidi_type[0]; i++)
394 395
    char_table_set_range (bidi_type_table, bidi_type[i].from,
			  bidi_type[i].to ? bidi_type[i].to : bidi_type[i].from,
Eli Zaretskii's avatar
Eli Zaretskii committed
396
			  make_number (bidi_type[i].type));
397 398 399 400 401 402 403 404 405 406 407 408 409 410 411

  fallback_paragraph_start_re =
    XSYMBOL (Fintern_soft (build_string ("paragraph-start"), Qnil))->value;
  if (!STRINGP (fallback_paragraph_start_re))
    fallback_paragraph_start_re = build_string ("\f\\|[ \t]*$");
  staticpro (&fallback_paragraph_start_re);
  Qparagraph_start = intern ("paragraph-start");
  staticpro (&Qparagraph_start);
  fallback_paragraph_separate_re =
    XSYMBOL (Fintern_soft (build_string ("paragraph-separate"), Qnil))->value;
  if (!STRINGP (fallback_paragraph_separate_re))
    fallback_paragraph_separate_re = build_string ("[ \t\f]*$");
  staticpro (&fallback_paragraph_separate_re);
  Qparagraph_separate = intern ("paragraph-separate");
  staticpro (&Qparagraph_separate);
Eli Zaretskii's avatar
Eli Zaretskii committed
412 413 414
  bidi_initialized = 1;
}

415 416
/* Return the bidi type of a character CH, subject to the current
   directional OVERRIDE.  */
Eli Zaretskii's avatar
Eli Zaretskii committed
417
bidi_type_t
418
bidi_get_type (int ch, bidi_dir_t override)
Eli Zaretskii's avatar
Eli Zaretskii committed
419
{
420 421
  bidi_type_t default_type;

422 423
  if (ch == BIDI_EOB)
    return NEUTRAL_B;
424 425
  if (ch < 0 || ch > MAX_CHAR)
    abort ();
426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457

  default_type = (bidi_type_t) XINT (CHAR_TABLE_REF (bidi_type_table, ch));

  if (override == NEUTRAL_DIR)
    return default_type;

  switch (default_type)
    {
      /* Although UAX#9 does not tell, it doesn't make sense to
	 override NEUTRAL_B and LRM/RLM characters.  */
      case NEUTRAL_B:
      case LRE:
      case LRO:
      case RLE:
      case RLO:
      case PDF:
	return default_type;
      default:
	switch (ch)
	  {
	    case LRM_CHAR:
	    case RLM_CHAR:
	      return default_type;
	    default:
	      if (override == L2R) /* X6 */
		return STRONG_L;
	      else if (override == R2L)
		return STRONG_R;
	      else
		abort ();	/* can't happen: handled above */
	  }
    }
Eli Zaretskii's avatar
Eli Zaretskii committed
458 459
}

460 461 462 463 464 465 466
void
bidi_check_type (bidi_type_t type)
{
  if (type < UNKNOWN_BT || type > NEUTRAL_ON)
    abort ();
}

Eli Zaretskii's avatar
Eli Zaretskii committed
467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501
/* Given a bidi TYPE of a character, return its category.  */
bidi_category_t
bidi_get_category (bidi_type_t type)
{
  switch (type)
    {
      case UNKNOWN_BT:
	return UNKNOWN_BC;
      case STRONG_L:
      case STRONG_R:
      case STRONG_AL:
      case LRE:
      case LRO:
      case RLE:
      case RLO:
	return STRONG;
      case PDF:		/* ??? really?? */
      case WEAK_EN:
      case WEAK_ES:
      case WEAK_ET:
      case WEAK_AN:
      case WEAK_CS:
      case WEAK_NSM:
      case WEAK_BN:
	return WEAK;
      case NEUTRAL_B:
      case NEUTRAL_S:
      case NEUTRAL_WS:
      case NEUTRAL_ON:
	return NEUTRAL;
      default:
	abort ();
    }
}

502 503 504 505
/* Return the mirrored character of C, if any.

   Note: The conditions in UAX#9 clause L4 must be tested by the
   caller.  */
Eli Zaretskii's avatar
Eli Zaretskii committed
506 507 508 509 510 511
/* FIXME: exceedingly temporary!  Should consult the Unicode database
   of character properties.  */
int
bidi_mirror_char (int c)
{
  static const char mirrored_pairs[] = "()<>[]{}";
512
  const char *p = c > 0 && c < 128 ? strchr (mirrored_pairs, c) : NULL;
Eli Zaretskii's avatar
Eli Zaretskii committed
513 514 515 516 517

  if (p)
    {
      size_t i = p - mirrored_pairs;

518
      return mirrored_pairs [(i ^ 1)];
Eli Zaretskii's avatar
Eli Zaretskii committed
519 520 521 522 523 524 525 526 527 528 529
    }
  return c;
}

/* Copy the bidi iterator from FROM to TO.  To save cycles, this only
   copies the part of the level stack that is actually in use.  */
static inline void
bidi_copy_it (struct bidi_it *to, struct bidi_it *from)
{
  int i;

530 531
  /* Copy everything except the level stack and beyond.  */
  memcpy (to, from, ((size_t)&((struct bidi_it *)0)->level_stack[0]));
Eli Zaretskii's avatar
Eli Zaretskii committed
532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672

  /* Copy the active part of the level stack.  */
  to->level_stack[0] = from->level_stack[0]; /* level zero is always in use */
  for (i = 1; i <= from->stack_idx; i++)
    to->level_stack[i] = from->level_stack[i];
}

/* Caching the bidi iterator states.  */

static struct bidi_it bidi_cache[1000]; /* FIXME: make this dynamically allocated! */
static int bidi_cache_idx;
static int bidi_cache_last_idx;

static inline void
bidi_cache_reset (void)
{
  bidi_cache_idx = 0;
  bidi_cache_last_idx = -1;
}

static inline void
bidi_cache_fetch_state (int idx, struct bidi_it *bidi_it)
{
  int current_scan_dir = bidi_it->scan_dir;

  if (idx < 0 || idx >= bidi_cache_idx)
    abort ();

  bidi_copy_it (bidi_it, &bidi_cache[idx]);
  bidi_it->scan_dir = current_scan_dir;
  bidi_cache_last_idx = idx;
}

/* Find a cached state with a given CHARPOS and resolved embedding
   level less or equal to LEVEL.  if LEVEL is -1, disregard the
   resolved levels in cached states.  DIR, if non-zero, means search
   in that direction from the last cache hit.  */
static inline int
bidi_cache_search (int charpos, int level, int dir)
{
  int i, i_start;

  if (bidi_cache_idx)
    {
      if (charpos < bidi_cache[bidi_cache_last_idx].charpos)
	dir = -1;
      else if (charpos > bidi_cache[bidi_cache_last_idx].charpos)
	dir = 1;
      if (dir)
	i_start = bidi_cache_last_idx;
      else
	{
	  dir = -1;
	  i_start = bidi_cache_idx - 1;
	}

      if (dir < 0)
	{
	  /* Linear search for now; FIXME!  */
	  for (i = i_start; i >= 0; i--)
	    if (bidi_cache[i].charpos == charpos
		&& (level == -1 || bidi_cache[i].resolved_level <= level))
	      return i;
	}
      else
	{
	  for (i = i_start; i < bidi_cache_idx; i++)
	    if (bidi_cache[i].charpos == charpos
		&& (level == -1 || bidi_cache[i].resolved_level <= level))
	      return i;
	}
    }

  return -1;
}

/* Find a cached state where the resolved level changes to a value
   that is lower than LEVEL, and return its cache slot index.  DIR is
   the direction to search, starting with the last used cache slot.
   BEFORE, if non-zero, means return the index of the slot that is
   ``before'' the level change in the search direction.  That is,
   given the cached levels like this:

	 1122333442211
	  AB        C

   and assuming we are at the position cached at the slot marked with
   C, searching backwards (DIR = -1) for LEVEL = 2 will return the
   index of slot B or A, depending whether BEFORE is, respectively,
   non-zero or zero.  */
static int
bidi_cache_find_level_change (int level, int dir, int before)
{
  if (bidi_cache_idx)
    {
      int i = dir ? bidi_cache_last_idx : bidi_cache_idx - 1;
      int incr = before ? 1 : 0;

      if (!dir)
	dir = -1;
      else if (!incr)
	i += dir;

      if (dir < 0)
	{
	  while (i >= incr)
	    {
	      if (bidi_cache[i - incr].resolved_level >= 0
		  && bidi_cache[i - incr].resolved_level < level)
		return i;
	      i--;
	    }
	}
      else
	{
	  while (i < bidi_cache_idx - incr)
	    {
	      if (bidi_cache[i + incr].resolved_level >= 0
		  && bidi_cache[i + incr].resolved_level < level)
		return i;
	      i++;
	    }
	}
    }

  return -1;
}

static inline void
bidi_cache_iterator_state (struct bidi_it *bidi_it, int resolved)
{
  int idx;

  /* We should never cache on backward scans.  */
  if (bidi_it->scan_dir == -1)
    abort ();
  idx = bidi_cache_search (bidi_it->charpos, -1, 1);

  if (idx < 0)
    {
      idx = bidi_cache_idx;
673
      /* Don't overrun the cache limit.  */
Eli Zaretskii's avatar
Eli Zaretskii committed
674 675
      if (idx > sizeof (bidi_cache) / sizeof (bidi_cache[0]) - 1)
	abort ();
676 677 678 679
      /* Don't violate cache integrity: character positions should
	 correspond to cache positions 1:1.  */
      if (idx > 0 && bidi_it->charpos != bidi_cache[idx - 1].charpos + 1)
	abort ();
Eli Zaretskii's avatar
Eli Zaretskii committed
680 681 682
      bidi_copy_it (&bidi_cache[idx], bidi_it);
      if (!resolved)
	bidi_cache[idx].resolved_level = -1;
683
      bidi_cache[idx].new_paragraph = 0;
Eli Zaretskii's avatar
Eli Zaretskii committed
684 685 686 687 688 689
    }
  else
    {
      /* Copy only the members which could have changed, to avoid
	 costly copying of the entire struct.  */
      bidi_cache[idx].type = bidi_it->type;
690
      bidi_check_type (bidi_it->type);
691 692
      bidi_cache[idx].type_after_w1 = bidi_it->type_after_w1;
      bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736
      if (resolved)
	bidi_cache[idx].resolved_level = bidi_it->resolved_level;
      else
	bidi_cache[idx].resolved_level = -1;
      bidi_cache[idx].invalid_levels = bidi_it->invalid_levels;
      bidi_cache[idx].invalid_rl_levels = bidi_it->invalid_rl_levels;
      bidi_cache[idx].next_for_neutral = bidi_it->next_for_neutral;
      bidi_cache[idx].next_for_ws = bidi_it->next_for_ws;
      bidi_cache[idx].ignore_bn_limit = bidi_it->ignore_bn_limit;
    }

  bidi_cache_last_idx = idx;
  if (idx >= bidi_cache_idx)
    bidi_cache_idx = idx + 1;
}

static inline bidi_type_t
bidi_cache_find (int charpos, int level, struct bidi_it *bidi_it)
{
  int i = bidi_cache_search (charpos, level, bidi_it->scan_dir);

  if (i >= 0)
    {
      bidi_dir_t current_scan_dir = bidi_it->scan_dir;

      *bidi_it = bidi_cache[i];
      bidi_cache_last_idx = i;
      /* Don't let scan direction from from the cached state override
	 the current scan direction.  */
      bidi_it->scan_dir = current_scan_dir;
      return bidi_it->type;
    }

  return UNKNOWN_BT;
}

static inline int
bidi_peek_at_next_level (struct bidi_it *bidi_it)
{
  if (bidi_cache_idx == 0 || bidi_cache_last_idx == -1)
    abort ();
  return bidi_cache[bidi_cache_last_idx + bidi_it->scan_dir].resolved_level;
}

737 738 739 740 741 742
/* Check if buffer position CHARPOS/BYTEPOS is the end of a paragraph.
   Value is the non-negative length of the paragraph separator
   following the buffer position, -1 if position is at the beginning
   of a new paragraph, or -2 if position is neither at beginning nor
   at end of a paragraph.  */
EMACS_INT
743
bidi_at_paragraph_end (EMACS_INT charpos, EMACS_INT bytepos)
Eli Zaretskii's avatar
Eli Zaretskii committed
744
{
745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763
  Lisp_Object sep_re = Fbuffer_local_value (Qparagraph_separate,
					    Fcurrent_buffer ());
  Lisp_Object start_re = Fbuffer_local_value (Qparagraph_start,
					      Fcurrent_buffer ());
  EMACS_INT val;

  if (!STRINGP (sep_re))
    sep_re = fallback_paragraph_separate_re;
  if (!STRINGP (start_re))
    start_re = fallback_paragraph_start_re;

  val = fast_looking_at (sep_re, charpos, bytepos, ZV, ZV_BYTE, Qnil);
  if (val < 0)
    {
      if (fast_looking_at (start_re, charpos, bytepos, ZV, ZV_BYTE, Qnil) >= 0)
	val = -1;
      else
	val = -2;
    }
Eli Zaretskii's avatar
Eli Zaretskii committed
764

765
  return val;
Eli Zaretskii's avatar
Eli Zaretskii committed
766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783
}

/* Determine the start-of-run (sor) directional type given the two
   embedding levels on either side of the run boundary.  Also, update
   the saved info about previously seen characters, since that info is
   generally valid for a single level run.  */
static inline void
bidi_set_sor_type (struct bidi_it *bidi_it, int level_before, int level_after)
{
  int higher_level = level_before > level_after ? level_before : level_after;

  /* The prev_was_pdf gork is required for when we have several PDFs
     in a row.  In that case, we want to compute the sor type for the
     next level run only once: when we see the first PDF.  That's
     because the sor type depends only on the higher of the two levels
     that we find on the two sides of the level boundary (see UAX#9,
     clause X10), and so we don't need to know the final embedding
     level to which we descend after processing all the PDFs.  */
784
  if (!bidi_it->prev_was_pdf || level_before < level_after)
Eli Zaretskii's avatar
Eli Zaretskii committed
785 786 787 788 789 790
    /* FIXME: should the default sor direction be user selectable?  */
    bidi_it->sor = (higher_level & 1) != 0 ? R2L : L2R;
  if (level_before > level_after)
    bidi_it->prev_was_pdf = 1;

  bidi_it->prev.type = UNKNOWN_BT;
791 792
  bidi_it->last_strong.type = bidi_it->last_strong.type_after_w1 =
    bidi_it->last_strong.orig_type = UNKNOWN_BT;
Eli Zaretskii's avatar
Eli Zaretskii committed
793 794 795
  bidi_it->prev_for_neutral.type = bidi_it->sor == R2L ? STRONG_R : STRONG_L;
  bidi_it->prev_for_neutral.charpos = bidi_it->charpos;
  bidi_it->prev_for_neutral.bytepos = bidi_it->bytepos;
796 797
  bidi_it->next_for_neutral.type = bidi_it->next_for_neutral.type_after_w1 =
    bidi_it->next_for_neutral.orig_type = UNKNOWN_BT;
Eli Zaretskii's avatar
Eli Zaretskii committed
798 799 800
  bidi_it->ignore_bn_limit = 0; /* meaning it's unknown */
}

801
static void
802 803 804 805 806 807 808 809 810
bidi_line_init (struct bidi_it *bidi_it)
{
  bidi_it->scan_dir = 1; /* FIXME: do we need to have control on this? */
  bidi_it->resolved_level = bidi_it->level_stack[0].level;
  bidi_it->level_stack[0].override = NEUTRAL_DIR; /* X1 */
  bidi_it->invalid_levels = 0;
  bidi_it->invalid_rl_levels = -1;
  bidi_it->next_en_pos = -1;
  bidi_it->next_for_ws.type = UNKNOWN_BT;
811 812
  bidi_set_sor_type (bidi_it,
		     bidi_it->paragraph_dir == R2L ? 1 : 0,
813 814 815 816 817 818 819 820
		     bidi_it->level_stack[0].level); /* X10 */

  bidi_cache_reset ();
}

/* Find the beginning of this paragraph by looking back in the buffer.
   Value is the byte position of the paragraph's beginning.  */
static EMACS_INT
821
bidi_find_paragraph_start (EMACS_INT pos, EMACS_INT pos_byte)
822
{
823
  Lisp_Object re = Fbuffer_local_value (Qparagraph_start, Fcurrent_buffer ());
824 825 826 827 828 829 830
  EMACS_INT limit = ZV, limit_byte = ZV_BYTE;

  if (!STRINGP (re))
    re = fallback_paragraph_start_re;
  while (pos_byte > BEGV_BYTE
	 && fast_looking_at (re, pos, pos_byte, limit, limit_byte, Qnil) < 0)
    {
831 832
      pos = find_next_newline_no_quit (pos - 1, -1);
      pos_byte = CHAR_TO_BYTE (pos);
833
    }
834
  return pos_byte;
835 836
}

837
/* Determine the direction, a.k.a. base embedding level, of the
838 839 840 841 842 843 844
   paragraph we are about to iterate through.  If DIR is either L2R or
   R2L, just use that.  Otherwise, determine the paragraph direction
   from the first strong character of the paragraph.

   Note that this gives the paragraph separator the same direction as
   the preceding paragraph, even though Emacs generally views the
   separartor as not belonging to any paragraph.  */
Eli Zaretskii's avatar
Eli Zaretskii committed
845 846 847
void
bidi_paragraph_init (bidi_dir_t dir, struct bidi_it *bidi_it)
{
848
  EMACS_INT bytepos = bidi_it->bytepos;
849

850 851 852
  /* Special case for an empty buffer. */
  if (bytepos == BEGV_BYTE && bytepos == ZV_BYTE)
    dir = L2R;
853
  /* We should never be called at EOB or before BEGV.  */
854
  else if (bytepos >= ZV_BYTE || bytepos < BEGV_BYTE)
855 856
    abort ();

857 858 859 860 861 862 863 864 865 866
  if (dir == L2R)
    {
      bidi_it->paragraph_dir = L2R;
      bidi_it->new_paragraph = 0;
    }
  else if (dir == R2L)
    {
      bidi_it->paragraph_dir = R2L;
      bidi_it->new_paragraph = 0;
    }
Eli Zaretskii's avatar
Eli Zaretskii committed
867 868
  else if (dir == NEUTRAL_DIR)	/* P2 */
    {
869 870 871
      int ch, ch_len;
      EMACS_INT pos;
      bidi_type_t type;
872 873 874 875
      EMACS_INT sep_len;

      /* If we are inside a paragraph separator, we are just waiting
	 for the separator to be exhausted; use the previous paragraph
876 877 878 879
	 direction.  But don't do that if we have been just reseated,
	 because we need to reinitialize below in that case.  */
      if (!bidi_it->first_elt
	  && bidi_it->charpos < bidi_it->separator_limit)
880 881
	return;

882
      /* If we are on a newline, get past it to where the next
883 884 885
	 paragraph might start.  But don't do that at BEGV since then
	 we are potentially in a new paragraph that doesn't yet
	 exist.  */
886
      pos = bidi_it->charpos;
887
      if (bytepos > BEGV_BYTE && FETCH_CHAR (bytepos) == '\n')
888
	{
889
	  bytepos++;
890
	  pos++;
891
	}
892 893 894 895

      /* We are either at the beginning of a paragraph or in the
	 middle of it.  Find where this paragraph starts.  */
      bytepos = bidi_find_paragraph_start (pos, bytepos);
896 897 898

      /* We should always be at the beginning of a new line at this
	 point.  */
899
      if (!(bytepos == BEGV_BYTE || FETCH_CHAR (bytepos - 1) == '\n'))
900 901
	abort ();

902 903
      bidi_it->separator_limit = -1;
      bidi_it->new_paragraph = 0;
904 905
      ch = FETCH_CHAR (bytepos);
      ch_len = CHAR_BYTES (ch);
906
      pos = BYTE_TO_CHAR (bytepos);
907
      type = bidi_get_type (ch, NEUTRAL_DIR);
Eli Zaretskii's avatar
Eli Zaretskii committed
908

909
      for (pos++, bytepos += ch_len;
Eli Zaretskii's avatar
Eli Zaretskii committed
910 911 912 913 914 915 916 917
	   /* NOTE: UAX#9 says to search only for L, AL, or R types of
	      characters, and ignore RLE, RLO, LRE, and LRO.  However,
	      I'm not sure it makes sense to omit those 4; should try
	      with and without that to see the effect.  */
	   (bidi_get_category (type) != STRONG)
	     || (bidi_ignore_explicit_marks_for_paragraph_level
		 && (type == RLE || type == RLO
		     || type == LRE || type == LRO));
918
	   type = bidi_get_type (ch, NEUTRAL_DIR))
Eli Zaretskii's avatar
Eli Zaretskii committed
919
	{
920
	  if (type == NEUTRAL_B && bidi_at_paragraph_end (pos, bytepos) >= -1)
Eli Zaretskii's avatar
Eli Zaretskii committed
921
	    break;
922 923 924 925 926 927
	  if (bytepos >= ZV_BYTE)
	    {
	      /* Pretend there's a paragraph separator at end of buffer.  */
	      type = NEUTRAL_B;
	      break;
	    }
Eli Zaretskii's avatar
Eli Zaretskii committed
928 929 930
	  FETCH_CHAR_ADVANCE (ch, pos, bytepos);
	}
      if (type == STRONG_R || type == STRONG_AL) /* P3 */
931 932 933
	bidi_it->paragraph_dir = R2L;
      else if (type == STRONG_L)
	bidi_it->paragraph_dir = L2R;
Eli Zaretskii's avatar
Eli Zaretskii committed
934
    }
935 936
  else
    abort ();
Eli Zaretskii's avatar
Eli Zaretskii committed
937

938 939 940
  /* Contrary to UAX#9 clause P3, we only default the paragraph
     direction to L2R if we have no previous usable paragraph
     direction.  */
941
  if (bidi_it->paragraph_dir == NEUTRAL_DIR)
942
    bidi_it->paragraph_dir = L2R; /* P3 and ``higher protocols'' */
943
  if (bidi_it->paragraph_dir == R2L)
944
    bidi_it->level_stack[0].level = 1;
945
  else
946
    bidi_it->level_stack[0].level = 0;
947 948

  bidi_line_init (bidi_it);
Eli Zaretskii's avatar
Eli Zaretskii committed
949 950
}

951 952
/* Do whatever UAX#9 clause X8 says should be done at paragraph's
   end.  */
Eli Zaretskii's avatar
Eli Zaretskii committed
953 954 955 956 957 958 959 960 961
static inline void
bidi_set_paragraph_end (struct bidi_it *bidi_it)
{
  bidi_it->invalid_levels = 0;
  bidi_it->invalid_rl_levels = -1;
  bidi_it->stack_idx = 0;
  bidi_it->resolved_level = bidi_it->level_stack[0].level;
}

962
/* Initialize the bidi iterator from buffer position CHARPOS.  */
Eli Zaretskii's avatar
Eli Zaretskii committed
963
void
964
bidi_init_it (EMACS_INT charpos, EMACS_INT bytepos, struct bidi_it *bidi_it)
Eli Zaretskii's avatar
Eli Zaretskii committed
965 966 967
{
  if (! bidi_initialized)
    bidi_initialize ();
968 969
  bidi_it->charpos = charpos;
  bidi_it->bytepos = bytepos;
970 971 972
  bidi_it->first_elt = 1;
  bidi_set_paragraph_end (bidi_it);
  bidi_it->new_paragraph = 1;
973
  bidi_it->separator_limit = -1;
974
  bidi_it->paragraph_dir = NEUTRAL_DIR;
Eli Zaretskii's avatar
Eli Zaretskii committed
975
  bidi_it->type = NEUTRAL_B;
976
  bidi_it->type_after_w1 = UNKNOWN_BT;
Eli Zaretskii's avatar
Eli Zaretskii committed
977 978
  bidi_it->orig_type = UNKNOWN_BT;
  bidi_it->prev_was_pdf = 0;
979 980 981
  bidi_it->prev.type = bidi_it->prev.type_after_w1 = UNKNOWN_BT;
  bidi_it->last_strong.type = bidi_it->last_strong.type_after_w1 =
    bidi_it->last_strong.orig_type = UNKNOWN_BT;
Eli Zaretskii's avatar
Eli Zaretskii committed
982 983
  bidi_it->next_for_neutral.charpos = -1;
  bidi_it->next_for_neutral.type =
984 985
    bidi_it->next_for_neutral.type_after_w1 =
    bidi_it->next_for_neutral.orig_type = UNKNOWN_BT;
Eli Zaretskii's avatar
Eli Zaretskii committed
986 987
  bidi_it->prev_for_neutral.charpos = -1;
  bidi_it->prev_for_neutral.type =
988 989
    bidi_it->prev_for_neutral.type_after_w1 =
    bidi_it->prev_for_neutral.orig_type = UNKNOWN_BT;
Eli Zaretskii's avatar
Eli Zaretskii committed
990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024
  bidi_it->sor = L2R;	 /* FIXME: should it be user-selectable? */
}

/* Push the current embedding level and override status; reset the
   current level to LEVEL and the current override status to OVERRIDE.  */
static inline void
bidi_push_embedding_level (struct bidi_it *bidi_it,
			   int level, bidi_dir_t override)
{
  bidi_it->stack_idx++;
  if (bidi_it->stack_idx >= BIDI_MAXLEVEL)
    abort ();
  bidi_it->level_stack[bidi_it->stack_idx].level = level;
  bidi_it->level_stack[bidi_it->stack_idx].override = override;
}

/* Pop the embedding level and directional override status from the
   stack, and return the new level.  */
static inline int
bidi_pop_embedding_level (struct bidi_it *bidi_it)
{
  /* UAX#9 says to ignore invalid PDFs.  */
  if (bidi_it->stack_idx > 0)
    bidi_it->stack_idx--;
  return bidi_it->level_stack[bidi_it->stack_idx].level;
}

/* Record in SAVED_INFO the information about the current character.  */
static inline void
bidi_remember_char (struct bidi_saved_info *saved_info,
		    struct bidi_it *bidi_it)
{
  saved_info->charpos = bidi_it->charpos;
  saved_info->bytepos = bidi_it->bytepos;
  saved_info->type = bidi_it->type;
1025
  bidi_check_type (bidi_it->type);
1026 1027
  saved_info->type_after_w1 = bidi_it->type_after_w1;
  bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
1028
  saved_info->orig_type = bidi_it->orig_type;
1029
  bidi_check_type (bidi_it->orig_type);
Eli Zaretskii's avatar
Eli Zaretskii committed
1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072
}

/* Resolve the type of a neutral character according to the type of
   surrounding strong text and the current embedding level.  */
static inline bidi_type_t
bidi_resolve_neutral_1 (bidi_type_t prev_type, bidi_type_t next_type, int lev)
{
  /* N1: European and Arabic numbers are treated as though they were R.  */
  if (next_type == WEAK_EN || next_type == WEAK_AN)
    next_type = STRONG_R;
  if (prev_type == WEAK_EN || prev_type == WEAK_AN)
    prev_type = STRONG_R;

  if (next_type == prev_type)	/* N1 */
    return next_type;
  else if ((lev & 1) == 0)	/* N2 */
    return STRONG_L;
  else
    return STRONG_R;
}

static inline int
bidi_explicit_dir_char (int c)
{
  /* FIXME: this should be replaced with a lookup table with suitable
     bits set, like standard C ctype macros do.  */
  return (c == LRE_CHAR || c == LRO_CHAR
	  || c == RLE_CHAR || c == RLO_CHAR || c == PDF_CHAR);
}

/* A helper function for bidi_resolve_explicit.  It advances to the
   next character in logical order and determines the new embedding
   level and directional override, but does not take into account
   empty embeddings.  */
static int
bidi_resolve_explicit_1 (struct bidi_it *bidi_it)
{
  int curchar;
  bidi_type_t type;
  int current_level;
  int new_level;
  bidi_dir_t override;

1073 1074
  if (bidi_it->bytepos < BEGV_BYTE	/* after reseat to BEGV? */
      || bidi_it->first_elt)
1075
    {
1076 1077 1078 1079
      bidi_it->first_elt = 0;
      if (bidi_it->charpos < BEGV)
	bidi_it->charpos = BEGV;
      bidi_it->bytepos = CHAR_TO_BYTE (bidi_it->charpos);
1080
    }
1081
  else if (bidi_it->bytepos < ZV_BYTE)	/* don't move at ZV */
Eli Zaretskii's avatar
Eli Zaretskii committed
1082 1083
    {
      bidi_it->charpos++;
1084 1085
      if (bidi_it->ch_len == 0)
	abort ();
Eli Zaretskii's avatar
Eli Zaretskii committed
1086 1087 1088 1089 1090 1091 1092 1093 1094
      bidi_it->bytepos += bidi_it->ch_len;
    }

  current_level = bidi_it->level_stack[bidi_it->stack_idx].level; /* X1 */
  override = bidi_it->level_stack[bidi_it->stack_idx].override;
  new_level = current_level;

  /* in case it is a unibyte character (not yet implemented) */
  /* _fetch_multibyte_char_len = 1; */
1095 1096 1097 1098 1099 1100 1101 1102 1103 1104
  if (bidi_it->bytepos >= ZV_BYTE)
    {
      curchar = BIDI_EOB;
      bidi_it->ch_len = 1;
    }
  else
    {
      curchar = FETCH_CHAR (bidi_it->bytepos);
      bidi_it->ch_len = CHAR_BYTES (curchar);
    }
Eli Zaretskii's avatar
Eli Zaretskii committed
1105 1106
  bidi_it->ch = curchar;

1107 1108 1109 1110 1111
  /* Don't apply directional override here, as all the types we handle
     below will not be affected by the override anyway, and we need
     the original type unaltered.  The override will be applied in
     bidi_resolve_weak.  */
  type = bidi_get_type (curchar, NEUTRAL_DIR);
1112 1113
  bidi_it->orig_type = type;
  bidi_check_type (bidi_it->orig_type);
Eli Zaretskii's avatar
Eli Zaretskii committed
1114 1115 1116 1117

  if (type != PDF)
    bidi_it->prev_was_pdf = 0;

1118
  bidi_it->type_after_w1 = UNKNOWN_BT;
Eli Zaretskii's avatar
Eli Zaretskii committed
1119 1120 1121 1122 1123

  switch (type)
    {
      case RLE:	/* X2 */
      case RLO:	/* X4 */
1124 1125
	bidi_it->type_after_w1 = type;
	bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
1126 1127 1128 1129 1130 1131 1132 1133
	type = WEAK_BN; /* X9/Retaining */
	if (bidi_it->ignore_bn_limit <= 0)
	  {
	    if (current_level <= BIDI_MAXLEVEL - 4)
	      {
		/* Compute the least odd embedding level greater than
		   the current level.  */
		new_level = ((current_level + 1) & ~1) + 1;
1134
		if (bidi_it->type_after_w1 == RLE)
Eli Zaretskii's avatar
Eli Zaretskii committed
1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150
		  override = NEUTRAL_DIR;
		else
		  override = R2L;
		if (current_level == BIDI_MAXLEVEL - 4)
		  bidi_it->invalid_rl_levels = 0;
		bidi_push_embedding_level (bidi_it, new_level, override);
	      }
	    else
	      {
		bidi_it->invalid_levels++;
		/* See the commentary about invalid_rl_levels below.  */
		if (bidi_it->invalid_rl_levels < 0)
		  bidi_it->invalid_rl_levels = 0;
		bidi_it->invalid_rl_levels++;
	      }
	  }
1151
	else if (bidi_it->prev.type_after_w1 == WEAK_EN /* W5/Retaining */
Eli Zaretskii's avatar
Eli Zaretskii committed
1152 1153 1154 1155 1156
		 || bidi_it->next_en_pos > bidi_it->charpos)
	  type = WEAK_EN;
	break;
      case LRE:	/* X3 */
      case LRO:	/* X5 */
1157 1158
	bidi_it->type_after_w1 = type;
	bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
1159 1160 1161 1162 1163 1164 1165 1166
	type = WEAK_BN; /* X9/Retaining */
	if (bidi_it->ignore_bn_limit <= 0)
	  {
	    if (current_level <= BIDI_MAXLEVEL - 5)
	      {
		/* Compute the least even embedding level greater than
		   the current level.  */
		new_level = ((current_level + 2) & ~1);
1167
		if (bidi_it->type_after_w1 == LRE)
Eli Zaretskii's avatar
Eli Zaretskii committed
1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186
		  override = NEUTRAL_DIR;
		else
		  override = L2R;
		bidi_push_embedding_level (bidi_it, new_level, override);
	      }
	    else
	      {
		bidi_it->invalid_levels++;
		/* invalid_rl_levels counts invalid levels encountered
		   while the embedding level was already too high for
		   LRE/LRO, but not for RLE/RLO.  That is because
		   there may be exactly one PDF which we should not
		   ignore even though invalid_levels is non-zero.
		   invalid_rl_levels helps to know what PDF is
		   that.  */
		if (bidi_it->invalid_rl_levels >= 0)
		  bidi_it->invalid_rl_levels++;
	      }
	  }
1187
	else if (bidi_it->prev.type_after_w1 == WEAK_EN /* W5/Retaining */
Eli Zaretskii's avatar
Eli Zaretskii committed
1188 1189 1190 1191
		 || bidi_it->next_en_pos > bidi_it->charpos)
	  type = WEAK_EN;
	break;
      case PDF:	/* X7 */
1192 1193
	bidi_it->type_after_w1 = type;
	bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212
	type = WEAK_BN; /* X9/Retaining */
	if (bidi_it->ignore_bn_limit <= 0)
	  {
	    if (!bidi_it->invalid_rl_levels)
	      {
		new_level = bidi_pop_embedding_level (bidi_it);
		bidi_it->invalid_rl_levels = -1;
		if (bidi_it->invalid_levels)
		  bidi_it->invalid_levels--;
		/* else nothing: UAX#9 says to ignore invalid PDFs */
	      }
	    if (!bidi_it->invalid_levels)
	      new_level = bidi_pop_embedding_level (bidi_it);
	    else
	      {
		bidi_it->invalid_levels--;
		bidi_it->invalid_rl_levels--;
	      }
	  }
1213
	else if (bidi_it->prev.type_after_w1 == WEAK_EN /* W5/Retaining */
Eli Zaretskii's avatar
Eli Zaretskii committed
1214 1215 1216 1217 1218 1219 1220 1221 1222
		 || bidi_it->next_en_pos > bidi_it->charpos)
	  type = WEAK_EN;
	break;
      default:
	/* Nothing.  */
	break;
    }

  bidi_it->type = type;
1223
  bidi_check_type (bidi_it->type);
Eli Zaretskii's avatar
Eli Zaretskii committed
1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241

  return new_level;
}

/* Given an iterator state in BIDI_IT, advance one character position
   in the buffer to the next character (in the logical order), resolve
   any explicit embeddings and directional overrides, and return the
   embedding level of the character after resolving explicit
   directives and ignoring empty embeddings.  */
static int
bidi_resolve_explicit (struct bidi_it *bidi_it)
{
  int prev_level = bidi_it->level_stack[bidi_it->stack_idx].level;
  int new_level  = bidi_resolve_explicit_1 (bidi_it);

  if (prev_level < new_level
      && bidi_it->type == WEAK_BN
      && bidi_it->ignore_bn_limit == 0 /* only if not already known */
1242
      && bidi_it->ch != BIDI_EOB       /* not already at EOB */
Eli Zaretskii's avatar
Eli Zaretskii committed
1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289
      && bidi_explicit_dir_char (FETCH_CHAR (bidi_it->bytepos
					     + bidi_it->ch_len)))
    {
      /* Avoid pushing and popping embedding levels if the level run
	 is empty, as this breaks level runs where it shouldn't.
	 UAX#9 removes all the explicit embedding and override codes,
	 so empty embeddings disappear without a trace.  We need to
	 behave as if we did the same.  */
      struct bidi_it saved_it;
      int level = prev_level;

      bidi_copy_it (&saved_it, bidi_it);

      while (bidi_explicit_dir_char (FETCH_CHAR (bidi_it->bytepos
						 + bidi_it->ch_len)))
	{
	  level = bidi_resolve_explicit_1 (bidi_it);
	}

      if (level == prev_level)	/* empty embedding */
	saved_it.ignore_bn_limit = bidi_it->charpos + 1;
      else			/* this embedding is non-empty */
	saved_it.ignore_bn_limit = -1;

      bidi_copy_it (bidi_it, &saved_it);
      if (bidi_it->ignore_bn_limit > 0)
	{
	  /* We pushed a level, but we shouldn't have.  Undo that. */
	  if (!bidi_it->invalid_rl_levels)
	    {
	      new_level = bidi_pop_embedding_level (bidi_it);
	      bidi_it->invalid_rl_levels = -1;
	      if (bidi_it->invalid_levels)
		bidi_it->invalid_levels--;
	    }
	  if (!bidi_it->invalid_levels)
	    new_level = bidi_pop_embedding_level (bidi_it);
	  else
	    {
	      bidi_it->invalid_levels--;
	      bidi_it->invalid_rl_levels--;
	    }
	}
    }

  if (bidi_it->type == NEUTRAL_B)	/* X8 */
    {
1290
      bidi_set_paragraph_end (bidi_it);
1291 1292
      /* This is needed by bidi_resolve_weak below, and in L1.  */
      bidi_it->type_after_w1 = bidi_it->type;
1293
      bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332
    }

  return new_level;
}

/* Advance in the buffer, resolve weak types and return the type of
   the next character after weak type resolution.  */
bidi_type_t
bidi_resolve_weak (struct bidi_it *bidi_it)
{
  bidi_type_t type;
  bidi_dir_t override;
  int prev_level = bidi_it->level_stack[bidi_it->stack_idx].level;
  int new_level  = bidi_resolve_explicit (bidi_it);
  int next_char;
  bidi_type_t type_of_next;
  struct bidi_it saved_it;

  type = bidi_it->type;
  override = bidi_it->level_stack[bidi_it->stack_idx].override;

  if (type == UNKNOWN_BT
      || type == LRE
      || type == LRO
      || type == RLE
      || type == RLO
      || type == PDF)
    abort ();

  if (new_level != prev_level
      || bidi_it->type == NEUTRAL_B)
    {
      /* We've got a new embedding level run, compute the directional
         type of sor and initialize per-run variables (UAX#9, clause
         X10).  */
      bidi_set_sor_type (bidi_it, prev_level, new_level);
    }
  else if (type == NEUTRAL_S || type == NEUTRAL_WS
	   || type == WEAK_BN || type == STRONG_AL)
1333 1334
    bidi_it->type_after_w1 = type;	/* needed in L1 */
  bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
1335 1336 1337 1338 1339 1340 1341

  /* Level and directional override status are already recorded in
     bidi_it, and do not need any change; see X6.  */
  if (override == R2L)		/* X6 */
    type = STRONG_R;
  else if (override == L2R)
    type = STRONG_L;
1342
  else
Eli Zaretskii's avatar
Eli Zaretskii committed
1343
    {
1344
      if (type == WEAK_NSM)	/* W1 */
Eli Zaretskii's avatar
Eli Zaretskii committed
1345
	{
1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358
	  /* Note that we don't need to consider the case where the
	     prev character has its type overridden by an RLO or LRO:
	     such characters are outside the current level run, and
	     thus not relevant to this NSM.  Thus, NSM gets the
	     orig_type of the previous character.  */
	  if (bidi_it->prev.type != UNKNOWN_BT)
	    type = bidi_it->prev.orig_type;
	  else if (bidi_it->sor == R2L)
	    type = STRONG_R;
	  else if (bidi_it->sor == L2R)
	    type = STRONG_L;
	  else /* shouldn't happen! */
	    abort ();
Eli Zaretskii's avatar
Eli Zaretskii committed
1359
	}
1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371
      if (type == WEAK_EN	/* W2 */
	  && bidi_it->last_strong.type_after_w1 == STRONG_AL)
	type = WEAK_AN;
      else if (type == STRONG_AL) /* W3 */
	type = STRONG_R;
      else if ((type == WEAK_ES	/* W4 */
		&& bidi_it->prev.type_after_w1 == WEAK_EN
		&& bidi_it->prev.orig_type == WEAK_EN)
	       || (type == WEAK_CS
		   && ((bidi_it->prev.type_after_w1 == WEAK_EN
			&& bidi_it->prev.orig_type == WEAK_EN)
		       || bidi_it->prev.type_after_w1 == WEAK_AN)))
Eli Zaretskii's avatar
Eli Zaretskii committed
1372
	{
1373 1374 1375
	  next_char =
	    bidi_it->bytepos + bidi_it->ch_len >= ZV_BYTE
	    ? BIDI_EOB : FETCH_CHAR (bidi_it->bytepos + bidi_it->ch_len);
1376
	  type_of_next = bidi_get_type (next_char, override);
Eli Zaretskii's avatar
Eli Zaretskii committed
1377

1378
	  if (type_of_next == WEAK_BN
Eli Zaretskii's avatar
Eli Zaretskii committed
1379 1380 1381 1382
	      || bidi_explicit_dir_char (next_char))
	    {
	      bidi_copy_it (&saved_it, bidi_it);
	      while (bidi_resolve_explicit (bidi_it) == new_level
1383
		     && bidi_it->type == WEAK_BN)
Eli Zaretskii's avatar
Eli Zaretskii committed
1384 1385 1386 1387
		;
	      type_of_next = bidi_it->type;
	      bidi_copy_it (bidi_it, &saved_it);
	    }
1388 1389 1390 1391 1392 1393 1394 1395 1396 1397

	  /* If the next character is EN, but the last strong-type
	     character is AL, that next EN will be changed to AN when
	     we process it in W2 above.  So in that case, this ES
	     should not be changed into EN.  */
	  if (type == WEAK_ES
	      && type_of_next == WEAK_EN
	      && bidi_it->last_strong.type_after_w1 != STRONG_AL)
	    type = WEAK_EN;
	  else if (type == WEAK_CS)
Eli Zaretskii's avatar
Eli Zaretskii committed
1398
	    {
1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443
	      if (bidi_it->prev.type_after_w1 == WEAK_AN
		  && (type_of_next == WEAK_AN
		      /* If the next character is EN, but the last
			 strong-type character is AL, EN will be later
			 changed to AN when we process it in W2 above.
			 So in that case, this ES should not be
			 changed into EN.  */
		      || (type_of_next == WEAK_EN
			  && bidi_it->last_strong.type_after_w1 == STRONG_AL)))
		type = WEAK_AN;
	      else if (bidi_it->prev.type_after_w1 == WEAK_EN
		       && type_of_next == WEAK_EN
		       && bidi_it->last_strong.type_after_w1 != STRONG_AL)
		type = WEAK_EN;
	    }
	}
      else if (type == WEAK_ET	/* W5: ET with EN before or after it */
	       || type == WEAK_BN)	/* W5/Retaining */
	{
	  if (bidi_it->prev.type_after_w1 == WEAK_EN /* ET/BN w/EN before it */
	      || bidi_it->next_en_pos > bidi_it->charpos)
	    type = WEAK_EN;
	  else			/* W5: ET/BN with EN after it.  */
	    {
	      EMACS_INT en_pos = bidi_it->charpos + 1;

	      next_char =
		bidi_it->bytepos + bidi_it->ch_len >= ZV_BYTE
		? BIDI_EOB : FETCH_CHAR (bidi_it->bytepos + bidi_it->ch_len);
	      type_of_next = bidi_get_type (next_char, override);

	      if (type_of_next == WEAK_ET
		  || type_of_next == WEAK_BN
		  || bidi_explicit_dir_char (next_char))
		{
		  bidi_copy_it (&saved_it, bidi_it);
		  while (bidi_resolve_explicit (bidi_it) == new_level
			 && (bidi_it->type == WEAK_BN
			     || bidi_it->type == WEAK_ET))
		    ;
		  type_of_next = bidi_it->type;
		  en_pos = bidi_it->charpos;
		  bidi_copy_it (bidi_it, &saved_it);
		}
	      if (type_of_next == WEAK_EN)
Eli Zaretskii's avatar
Eli Zaretskii committed
1444
		{
1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455
		  /* If the last strong character is AL, the EN we've
		     found will become AN when we get to it (W2). */
		  if (bidi_it->last_strong.type_after_w1 != STRONG_AL)
		    {
		      type = WEAK_EN;
		      /* Remember this EN position, to speed up processing
			 of the next ETs.  */
		      bidi_it->next_en_pos = en_pos;
		    }
		  else if (type == WEAK_BN)
		    type = NEUTRAL_ON; /* W6/Retaining */
Eli Zaretskii's avatar
Eli Zaretskii committed
1456 1457 1458 1459 1460 1461
		}
	    }
	}
    }

  if (type == WEAK_ES || type == WEAK_ET || type == WEAK_CS /* W6 */
1462 1463 1464 1465
      || (type == WEAK_BN
	  && (bidi_it->prev.type_after_w1 == WEAK_CS	    /* W6/Retaining */
	      || bidi_it->prev.type_after_w1 == WEAK_ES
	      || bidi_it->prev.type_after_w1 == WEAK_ET)))
Eli Zaretskii's avatar
Eli Zaretskii committed
1466 1467 1468 1469 1470 1471
    type = NEUTRAL_ON;

  /* Store the type we've got so far, before we clobber it with strong
     types in W7 and while resolving neutral types.  But leave alone
     the original types that were recorded above, because we will need
     them for the L1 clause.  */
1472 1473 1474
  if (bidi_it->type_after_w1 == UNKNOWN_BT)
    bidi_it->type_after_w1 = type;
  bidi_check_type (bidi_it->type_after_w1);
Eli Zaretskii's avatar
Eli Zaretskii committed
1475 1476 1477

  if (type == WEAK_EN)	/* W7 */
    {
1478
      if ((bidi_it->last_strong.type_after_w1 == STRONG_L)
Eli Zaretskii's avatar
Eli Zaretskii committed
1479 1480 1481 1482 1483
	  || (bidi_it->last_strong.type == UNKNOWN_BT && bidi_it->sor == L2R))
	type = STRONG_L;
    }

  bidi_it->type = type;
1484
  bidi_check_type (bidi_it->type);
Eli Zaretskii's avatar
Eli Zaretskii committed
1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537
  return type;
}

bidi_type_t
bidi_resolve_neutral (struct bidi_it *bidi_it)
{
  int prev_level = bidi_it->level_stack[bidi_it->stack_idx].level;
  bidi_type_t type = bidi_resolve_weak (bidi_it);
  int current_level = bidi_it->level_stack[bidi_it->stack_idx].level;

  if (!(type == STRONG_R
	|| type == STRONG_L
	|| type == WEAK_BN
	|| type == WEAK_EN
	|| type == WEAK_AN
	|| type == NEUTRAL_B
	|| type == NEUTRAL_S
	|| type == NEUTRAL_WS
	|| type == NEUTRAL_ON))
    abort ();

  if (bidi_get_category (type) == NEUTRAL
      || (type == WEAK_BN && prev_level == current_level))
    {
      if (bidi_it->next_for_neutral.type != UNKNOWN_BT)
	type = bidi_resolve_neutral_1 (bidi_it->prev_for_neutral.type,
				       bidi_it->next_for_neutral.type,
				       current_level);
      else
	{
	  /* Arrrgh!!  The UAX#9 algorithm is too deeply entrenched in
	     the assumption of batch-style processing; see clauses W4,
	     W5, and especially N1, which require to look far forward
	     (as well as back) in the buffer.  May the fleas of a
	     thousand camels infest the armpits of those who design
	     supposedly general-purpose algorithms by looking at their
	     own implementations, and fail to consider other possible
	     implementations!  */
	  struct bidi_it saved_it;
	  bidi_type_t next_type;

	  if (bidi_it->scan_dir == -1)
	    abort ();

	  bidi_copy_it (&saved_it, bidi_it);
	  /* Scan the text forward until we find the first non-neutral
	     character, and then use that to resolve the neutral we
	     are dealing with now.  We also cache the scanned iterator
	     states, to salvage some of the effort later.  */
	  bidi_cache_iterator_state (bidi_it, 0);
	  do {
	    /* Record the info about the previous character, so that
	       it will be cached below with this state.  */
1538
	    if (bidi_it->type_after_w1 != WEAK_BN /* W1/Retaining */
Eli Zaretskii's avatar
Eli Zaretskii committed
1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581
		&& bidi_it->type != WEAK_BN)
	      bidi_remember_char (&bidi_it->prev, bidi_it);
	    type = bidi_resolve_weak (bidi_it);
	    /* Paragraph separators have their levels fully resolved
	       at this point, so cache them as resolved.  */
	    bidi_cache_iterator_state (bidi_it, type == NEUTRAL_B);
	    /* FIXME: implement L1 here, by testing for a newline and
	       resetting the level for any sequence of whitespace
	       characters adjacent to it.  */
	  } while (!(type == NEUTRAL_B
		     || (type != WEAK_BN
			 && bidi_get_category (type) != NEUTRAL)
		     /* This is all per level run, so stop when we
			reach the end of this level run.  */
		     || bidi_it->level_stack[bidi_it->stack_idx].level !=
		     current_level));

	  bidi_remember_char (&saved_it.next_for_neutral, bidi_it);

	  switch (type)
	    {
	      case STRONG_L:
	      case STRONG_R:
	      case STRONG_AL:
		next_type = type;
		break;
	      case WEAK_EN:
	      case WEAK_AN:
		/* N1: ``European and Arabic numbers are treated as
		   though they were R.''  */
		next_type = STRONG_R;
		saved_it.next_for_neutral.type = STRONG_R;
		break;
	      case WEAK_BN:
		if (!bidi_explicit_dir_char (bidi_it->ch))
		  abort ();		/* can't happen: BNs are skipped */
		/* FALLTHROUGH */
	      case NEUTRAL_B:
		/* Marched all the way to the end of this level run.
		   We need to use the eor type, whose information is
		   stored by bidi_set_sor_type in the prev_for_neutral
		   member.  */
		if (saved_it.type != WEAK_BN
1582
		    || bidi_get_category (bidi_it->prev.type_after_w1) == NEUTRAL)
Eli Zaretskii's avatar
Eli Zaretskii committed
1583 1584 1585
		  {
		    next_type = bidi_it->prev_for_neutral.type;
		    saved_it.next_for_neutral.type = next_type;
1586
		    bidi_check_type (next_type);
Eli Zaretskii's avatar
Eli Zaretskii committed
1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601
		  }
		else
		  {
		    /* This is a BN which does not adjoin neutrals.
		       Leave its type alone.  */
		    bidi_copy_it (bidi_it, &saved_it);
		    return bidi_it->type;
		  }
		break;
	      default:
		abort ();
	    }
	  type = bidi_resolve_neutral_1 (saved_it.prev_for_neutral.type,
					 next_type, current_level);
	  saved_it.type = type;