summaryrefslogtreecommitdiffstats
path: root/src/mesa/shader/slang/slang_preprocess.c
blob: 244a09171c7db8f85d90d0c80e84c6df5454321a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
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
169
170
171
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
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
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
458
459
460
461
462
463
464
465
466
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
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
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
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
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
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
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
1025
1026
1027
1028
1029
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
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
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
/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 2005-2008  Brian Paul   All Rights Reserved.
 * Copyright (C) 2009 VMware, Inc.   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/**
 * \file slang_preprocess.c
 * slang preprocessor
 * \author Michal Krol
 */

#include "main/imports.h"
#include "shader/grammar/grammar_mesa.h"
#include "slang_preprocess.h"

LONGSTRING static const char *slang_pp_directives_syn =
#include "library/slang_pp_directives_syn.h"
;

LONGSTRING static const char *slang_pp_expression_syn =
#include "library/slang_pp_expression_syn.h"
;

LONGSTRING static const char *slang_pp_version_syn =
#include "library/slang_pp_version_syn.h"
;

static GLvoid
grammar_error_to_log (slang_info_log *log)
{
   char buf[1024];
   GLint pos;

   grammar_get_last_error ((byte *) (buf), sizeof (buf), &pos);
   if (buf[0] == 0) {
      _mesa_snprintf(buf, sizeof(buf), "Preprocessor error");
   }
   slang_info_log_error (log, buf);
}

GLboolean
_slang_preprocess_version (const char *text, GLuint *version, GLuint *eaten, slang_info_log *log)
{
   grammar id;
   byte *prod, *I;
   unsigned int size;

   id = grammar_load_from_text ((const byte *) (slang_pp_version_syn));
   if (id == 0) {
      grammar_error_to_log (log);
      return GL_FALSE;
   }

   if (!grammar_fast_check (id, (const byte *) (text), &prod, &size, 8)) {
      grammar_error_to_log (log);
      grammar_destroy (id);
      return GL_FALSE;
   }

   /* there can be multiple #version directives - grab the last one */
   I = &prod[size - 6];
   *version = (GLuint) (I[0]) + (GLuint) (I[1]) * 100;
   *eaten = (GLuint) (I[2]) + ((GLuint) (I[3]) << 8) + ((GLuint) (I[4]) << 16) + ((GLuint) (I[5]) << 24);

   grammar_destroy (id);
   grammar_alloc_free (prod);
   return GL_TRUE;
}

/*
 * The preprocessor does the following work.
 * 1. Remove comments. Each comment block is replaced with a single space and if the
 *    block contains new-lines, they are preserved. This ensures that line numbers
 *    stay the same and if a comment block delimits two tokens, the are delitmited
 *    by the space after comment removal.
 * 2. Remove preprocessor directives from the source string, checking their syntax and
 *    executing them if appropriate. Again, new-lines are preserved.
 * 3. Expand macros.
 * 4. Tokenize the source string by ensuring there is at least one space between every
 *    two adjacent tokens.
 */

#define PP_ANNOTATE 0

static GLvoid
pp_annotate (slang_string *output, const char *fmt, ...)
{
#if PP_ANNOTATE
   va_list va;
   char buffer[1024];

   va_start (va, fmt);
   _mesa_vsprintf (buffer, fmt, va);
   va_end (va);
   slang_string_pushs (output, buffer, _mesa_strlen (buffer));
#else
   (GLvoid) (output);
   (GLvoid) (fmt);
#endif
}

 /*
 * The expression is executed on a fixed-sized stack. The PUSH macro makes a runtime
 * check if the stack is not overflown by too complex expressions. In that situation the
 * GLSL preprocessor should report internal compiler error.
 * The BINARYDIV makes a runtime check if the divider is not 0. If it is, it reports
 * compilation error.
 */

#define EXECUTION_STACK_SIZE 1024

#define PUSH(x)\
   do {\
      if (sp == 0) {\
         slang_info_log_error (elog, "internal compiler error: preprocessor execution stack overflow.");\
         return GL_FALSE;\
      }\
      stack[--sp] = x;\
   } while (GL_FALSE)

#define POP(x)\
   do {\
      assert (sp < EXECUTION_STACK_SIZE);\
      x = stack[sp++];\
   } while (GL_FALSE)

#define BINARY(op)\
   do {\
      GLint a, b;\
      POP(b);\
      POP(a);\
      PUSH(a op b);\
   } while (GL_FALSE)

#define BINARYDIV(op)\
   do {\
      GLint a, b;\
      POP(b);\
      POP(a);\
      if (b == 0) {\
         slang_info_log_error (elog, "division by zero in preprocessor expression.");\
         return GL_FALSE;\
      }\
      PUSH(a op b);\
   } while (GL_FALSE)

#define UNARY(op)\
   do {\
      GLint a;\
      POP(a);\
      PUSH(op a);\
   } while (GL_FALSE)

#define OP_END          0
#define OP_PUSHINT      1
#define OP_LOGICALOR    2
#define OP_LOGICALAND   3
#define OP_OR           4
#define OP_XOR          5
#define OP_AND          6
#define OP_EQUAL        7
#define OP_NOTEQUAL     8
#define OP_LESSEQUAL    9
#define OP_GREATEREQUAL 10
#define OP_LESS         11
#define OP_GREATER      12
#define OP_LEFTSHIFT    13
#define OP_RIGHTSHIFT   14
#define OP_ADD          15
#define OP_SUBTRACT     16
#define OP_MULTIPLY     17
#define OP_DIVIDE       18
#define OP_MODULUS      19
#define OP_PLUS         20
#define OP_MINUS        21
#define OP_NEGATE       22
#define OP_COMPLEMENT   23

static GLboolean
execute_expression (slang_string *output, const byte *code, GLuint *pi, GLint *result,
                    slang_info_log *elog)
{
   GLuint i = *pi;
   GLint stack[EXECUTION_STACK_SIZE];
   GLuint sp = EXECUTION_STACK_SIZE;

   while (code[i] != OP_END) {
      switch (code[i++]) {
         case OP_PUSHINT:
            i++;
            PUSH(_mesa_atoi ((const char *) (&code[i])));
            i += _mesa_strlen ((const char *) (&code[i])) + 1;
            break;
         case OP_LOGICALOR:
            BINARY(||);
            break;
         case OP_LOGICALAND:
            BINARY(&&);
            break;
         case OP_OR:
            BINARY(|);
            break;
         case OP_XOR:
            BINARY(^);
            break;
         case OP_AND:
            BINARY(&);
            break;
         case OP_EQUAL:
            BINARY(==);
            break;
         case OP_NOTEQUAL:
            BINARY(!=);
            break;
         case OP_LESSEQUAL:
            BINARY(<=);
            break;
         case OP_GREATEREQUAL:
            BINARY(>=);
            break;
         case OP_LESS:
            BINARY(<);
            break;
         case OP_GREATER:
            BINARY(>);
            break;
         case OP_LEFTSHIFT:
            BINARY(<<);
            break;
         case OP_RIGHTSHIFT:
            BINARY(>>);
            break;
         case OP_ADD:
            BINARY(+);
            break;
         case OP_SUBTRACT:
            BINARY(-);
            break;
         case OP_MULTIPLY:
            BINARY(*);
            break;
         case OP_DIVIDE:
            BINARYDIV(/);
            break;
         case OP_MODULUS:
            BINARYDIV(%);
            break;
         case OP_PLUS:
            UNARY(+);
            break;
         case OP_MINUS:
            UNARY(-);
            break;
         case OP_NEGATE:
            UNARY(!);
            break;
         case OP_COMPLEMENT:
            UNARY(~);
            break;
         default:
            assert (0);
      }
   }

   /* Write-back the index skipping the OP_END. */
   *pi = i + 1;

   /* There should be exactly one value left on the stack. This is our result. */
   POP(*result);
   pp_annotate (output, "%d ", *result);
   assert (sp == EXECUTION_STACK_SIZE);
   return GL_TRUE;
}

/*
 * Function execute_expressions() executes up to 2 expressions. The second expression is there
 * for the #line directive which takes 1 or 2 expressions that indicate line and file numbers.
 * If it fails, it returns 0. If it succeeds, it returns the number of executed expressions.
 */

#define EXP_END        0
#define EXP_EXPRESSION 1

static GLuint
execute_expressions (slang_string *output, grammar eid, const byte *expr, GLint results[2],
                     slang_info_log *elog)
{
   GLint success;
   byte *code;
   GLuint size, count = 0;

   success = grammar_fast_check (eid, expr, &code, &size, 64);
   if (success) {
      GLuint i = 0;

      while (code[i++] == EXP_EXPRESSION) {
         assert (count < 2);

         if (!execute_expression (output, code, &i, &results[count], elog)) {
            count = 0;
            break;
         }
         count++;
      }
      grammar_alloc_free (code);
   }
   else {
      slang_info_log_error (elog, "syntax error in preprocessor expression.");\
   }
   return count;
}

/*
 * The pp_symbol structure is used to hold macro definitions and macro formal parameters. The
 * pp_symbols strcture is a collection of pp_symbol. It is used both for storing macro formal
 * parameters and all global macro definitions. Making this unification wastes some memory,
 * becuse macro formal parameters don't need further lists of symbols. We lose 8 bytes per
 * formal parameter here, but making this we can use the same code to substitute macro parameters
 * as well as macros in the source string.
 */

typedef struct
{
   struct pp_symbol_ *symbols;
   GLuint count;
} pp_symbols;

static GLvoid
pp_symbols_init (pp_symbols *self)
{
   self->symbols = NULL;
   self->count = 0;
}

static GLvoid
pp_symbols_free (pp_symbols *);

typedef struct pp_symbol_
{
   slang_string name;
   slang_string replacement;
   pp_symbols parameters;
} pp_symbol;

static GLvoid
pp_symbol_init (pp_symbol *self)
{
   slang_string_init (&self->name);
   slang_string_init (&self->replacement);
   pp_symbols_init (&self->parameters);
}

static GLvoid
pp_symbol_free (pp_symbol *self)
{
   slang_string_free (&self->name);
   slang_string_free (&self->replacement);
   pp_symbols_free (&self->parameters);
}

static GLvoid
pp_symbol_reset (pp_symbol *self)
{
   /* Leave symbol name intact. */
   slang_string_reset (&self->replacement);
   pp_symbols_free (&self->parameters);
   pp_symbols_init (&self->parameters);
}

static GLvoid
pp_symbols_free (pp_symbols *self)
{
   GLuint i;

   for (i = 0; i < self->count; i++)
      pp_symbol_free (&self->symbols[i]);
   _mesa_free (self->symbols);
}

static pp_symbol *
pp_symbols_push (pp_symbols *self)
{
   self->symbols = (pp_symbol *) (_mesa_realloc (self->symbols, self->count * sizeof (pp_symbol),
                                                 (self->count + 1) * sizeof (pp_symbol)));
   if (self->symbols == NULL)
      return NULL;
   pp_symbol_init (&self->symbols[self->count]);
   return &self->symbols[self->count++];
}

static GLboolean
pp_symbols_erase (pp_symbols *self, pp_symbol *symbol)
{
   assert (symbol >= self->symbols && symbol < self->symbols + self->count);

   self->count--;
   pp_symbol_free (symbol);
   if (symbol < self->symbols + self->count)
      _mesa_memcpy (symbol, symbol + 1, sizeof (pp_symbol) * (self->symbols + self->count - symbol));
   self->symbols = (pp_symbol *) (_mesa_realloc (self->symbols, (self->count + 1) * sizeof (pp_symbol),
                                                 self->count * sizeof (pp_symbol)));
   return self->symbols != NULL;
}

static pp_symbol *
pp_symbols_find (pp_symbols *self, const char *name)
{
   GLuint i;

   for (i = 0; i < self->count; i++)
      if (_mesa_strcmp (name, slang_string_cstr (&self->symbols[i].name)) == 0)
         return &self->symbols[i];
   return NULL;
}

/*
 * The condition context of a single #if/#else/#endif level. Those can be nested, so there
 * is a stack of condition contexts.
 * There is a special global context on the bottom of the stack. It is there to simplify
 * context handling.
 */

typedef struct
{
   GLboolean current;         /* The condition value of this level. */
   GLboolean effective;       /* The effective product of current condition, outer level conditions
                               * and position within #if-#else-#endif sections. */
   GLboolean else_allowed;    /* TRUE if in #if-#else section, FALSE if in #else-#endif section
                               * and for global context. */
   GLboolean endif_required;  /* FALSE for global context only. */
} pp_cond_ctx;

/* Should be enuff. */
#define CONDITION_STACK_SIZE 64

typedef struct
{
   pp_cond_ctx stack[CONDITION_STACK_SIZE];
   pp_cond_ctx *top;
} pp_cond_stack;

static GLboolean
pp_cond_stack_push (pp_cond_stack *self, slang_info_log *elog)
{
   if (self->top == self->stack) {
      slang_info_log_error (elog, "internal compiler error: preprocessor condition stack overflow.");
      return GL_FALSE;
   }
   self->top--;
   return GL_TRUE;
}

static GLvoid
pp_cond_stack_reevaluate (pp_cond_stack *self)
{
   /* There must be at least 2 conditions on the stack - one global and one being evaluated. */
   assert (self->top <= &self->stack[CONDITION_STACK_SIZE - 2]);

   self->top->effective = self->top->current && self->top[1].effective;
}


/**
 * Extension enables through #extension directive.
 * NOTE: Currently, only enable/disable state is stored.
 */
typedef struct
{
   GLboolean ARB_draw_buffers;
   GLboolean ARB_texture_rectangle;
} pp_ext;


/**
 * Disable all extensions. Called at startup and on #extension all: disable.
 */
static GLvoid
pp_ext_disable_all(pp_ext *self)
{
   _mesa_memset(self, 0, sizeof(self));
}


/**
 * Called during preprocessor initialization to set the initial enable/disable
 * state of extensions.
 */
static GLvoid
pp_ext_init(pp_ext *self, const struct gl_extensions *extensions)
{
   pp_ext_disable_all (self);
   if (extensions->ARB_draw_buffers)
      self->ARB_draw_buffers = GL_TRUE;
   if (extensions->NV_texture_rectangle)
      self->ARB_texture_rectangle = GL_TRUE;
}

/**
 * Called in response to #extension directives to enable/disable
 * the named extension.
 */
static GLboolean
pp_ext_set(pp_ext *self, const char *name, GLboolean enable)
{
   if (_mesa_strcmp (name, "GL_ARB_draw_buffers") == 0)
      self->ARB_draw_buffers = enable;
   else if (_mesa_strcmp (name, "GL_ARB_texture_rectangle") == 0)
      self->ARB_texture_rectangle = enable;
   else
      return GL_FALSE;
   return GL_TRUE;
}


/**
 * Called in response to #pragma.  For example, "#pragma debug(on)" would
 * call this function as pp_pragma("debug", "on").
 * At this time, pragmas are silently ignored.
 */
static void
pp_pragma(const char *pragma, const char *param)
{
#if 0
   printf("#pragma %s %s\n", pragma, param);
#endif
}


/**
 * The state of preprocessor: current line, file and version number, list
 * of all defined macros and the #if/#endif context.
 */
typedef struct
{
   GLint line;
   GLint file;
   GLint version;
   pp_symbols symbols;
   pp_ext ext;
   slang_info_log *elog;
   pp_cond_stack cond;
} pp_state;

static GLvoid
pp_state_init (pp_state *self, slang_info_log *elog,
               const struct gl_extensions *extensions)
{
   self->line = 0;
   self->file = 1;
#if FEATURE_es2_glsl
   self->version = 100;
#else
   self->version = 110;
#endif
   pp_symbols_init (&self->symbols);
   pp_ext_init (&self->ext, extensions);
   self->elog = elog;

   /* Initialize condition stack and create the global context. */
   self->cond.top = &self->cond.stack[CONDITION_STACK_SIZE - 1];
   self->cond.top->current = GL_TRUE;
   self->cond.top->effective = GL_TRUE;
   self->cond.top->else_allowed = GL_FALSE;
   self->cond.top->endif_required = GL_FALSE;
}

static GLvoid
pp_state_free (pp_state *self)
{
   pp_symbols_free (&self->symbols);
}

#define IS_FIRST_ID_CHAR(x) (((x) >= 'a' && (x) <= 'z') || ((x) >= 'A' && (x) <= 'Z') || (x) == '_')
#define IS_NEXT_ID_CHAR(x) (IS_FIRST_ID_CHAR(x) || ((x) >= '0' && (x) <= '9'))
#define IS_WHITE(x) ((x) == ' ' || (x) == '\n')
#define IS_NULL(x) ((x) == '\0')

#define SKIP_WHITE(x) do { while (IS_WHITE(*(x))) (x)++; } while (GL_FALSE)

typedef struct
{
   slang_string *output;
   const char *input;
   pp_state *state;
} expand_state;

static GLboolean
expand_defined (expand_state *e, slang_string *buffer)
{
   GLboolean in_paren = GL_FALSE;
   const char *id;

   /* Parse the optional opening parenthesis. */
   SKIP_WHITE(e->input);
   if (*e->input == '(') {
      e->input++;
      in_paren = GL_TRUE;
      SKIP_WHITE(e->input);
   }

   /* Parse operand. */
   if (!IS_FIRST_ID_CHAR(*e->input)) {
      slang_info_log_error (e->state->elog,
                            "preprocess error: identifier expected after operator 'defined'.");
      return GL_FALSE;
   }
   slang_string_reset (buffer);
   slang_string_pushc (buffer, *e->input++);
   while (IS_NEXT_ID_CHAR(*e->input))
      slang_string_pushc (buffer, *e->input++);
   id = slang_string_cstr (buffer);

   /* Check if the operand is defined. Output 1 if it is defined, output 0 if not. */
   if (pp_symbols_find (&e->state->symbols, id) == NULL)
      slang_string_pushs (e->output, " 0 ", 3);
   else
      slang_string_pushs (e->output, " 1 ", 3);

   /* Parse the closing parentehesis if the opening one was there. */
   if (in_paren) {
      SKIP_WHITE(e->input);
      if (*e->input != ')') {
         slang_info_log_error (e->state->elog, "preprocess error: ')' expected.");
         return GL_FALSE;
      }
      e->input++;
      SKIP_WHITE(e->input);
   }
   return GL_TRUE;
}

static GLboolean
expand (expand_state *, pp_symbols *);

static GLboolean
expand_symbol (expand_state *e, pp_symbol *symbol)
{
   expand_state es;

   /* If the macro has some parameters, we need to parse them. */
   if (symbol->parameters.count != 0) {
      GLuint i;

      /* Parse the opening parenthesis. */
      SKIP_WHITE(e->input);
      if (*e->input != '(') {
         slang_info_log_error (e->state->elog, "preprocess error: '(' expected.");
         return GL_FALSE;
      }
      e->input++;
      SKIP_WHITE(e->input);

      /* Parse macro actual parameters. This can be anything, separated by a colon.
       */
      for (i = 0; i < symbol->parameters.count; i++) {
         GLuint nested_paren_count = 0; /* track number of nested parentheses */

         if (*e->input == ')') {
            slang_info_log_error (e->state->elog, "preprocess error: unexpected ')'.");
            return GL_FALSE;
         }

         /* Eat all characters up to the comma or closing parentheses. */
         pp_symbol_reset (&symbol->parameters.symbols[i]);
         while (!IS_NULL(*e->input)) {
            /* Exit loop only when all nested parens have been eaten. */
            if (nested_paren_count == 0 && (*e->input == ',' || *e->input == ')'))
               break;

            /* Actually count nested parens here. */
            if (*e->input == '(')
               nested_paren_count++;
            else if (*e->input == ')')
               nested_paren_count--;

            slang_string_pushc (&symbol->parameters.symbols[i].replacement, *e->input++);
         }

         /* If it was not the last paremeter, skip the comma. Otherwise, skip the
          * closing parentheses. */
         if (i + 1 == symbol->parameters.count) {
            /* This is the last paremeter - skip the closing parentheses. */
            if (*e->input != ')') {
               slang_info_log_error (e->state->elog, "preprocess error: ')' expected.");
               return GL_FALSE;
            }
            e->input++;
            SKIP_WHITE(e->input);
         }
         else {
            /* Skip the separating comma. */
            if (*e->input != ',') {
               slang_info_log_error (e->state->elog, "preprocess error: ',' expected.");
               return GL_FALSE;
            }
            e->input++;
            SKIP_WHITE(e->input);
         }
      }
   }

   /* Expand the macro. Use its parameters as a priority symbol list to expand
    * macro parameters correctly. */
   es.output = e->output;
   es.input = slang_string_cstr (&symbol->replacement);
   es.state = e->state;
   slang_string_pushc (e->output, ' ');
   if (!expand (&es, &symbol->parameters))
      return GL_FALSE;
   slang_string_pushc (e->output, ' ');
   return GL_TRUE;
}

/*
 * Function expand() expands source text from <input> to <output>. The expansion is made using
 * the list passed in <symbols> parameter. It allows us to expand macro formal parameters with
 * actual parameters. The global list of symbols from pp state is used when doing a recursive
 * call of expand().
 */

static GLboolean
expand (expand_state *e, pp_symbols *symbols)
{
   while (!IS_NULL(*e->input)) {
      if (IS_FIRST_ID_CHAR(*e->input)) {
         slang_string buffer;
         const char *id;

         /* Parse the identifier. */
         slang_string_init (&buffer);
         slang_string_pushc (&buffer, *e->input++);
         while (IS_NEXT_ID_CHAR(*e->input))
            slang_string_pushc (&buffer, *e->input++);
         id = slang_string_cstr (&buffer);

         /* Now check if the identifier is special in some way. The "defined" identifier is
          * actually an operator that we must handle here and expand it either to " 0 " or " 1 ".
          * The other identifiers start with "__" and we expand it to appropriate values
          * taken from the preprocessor state. */
         if (_mesa_strcmp (id, "defined") == 0) {
            if (!expand_defined (e, &buffer))
               return GL_FALSE;
         }
         else if (_mesa_strcmp (id, "__LINE__") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, e->state->line);
            slang_string_pushc (e->output, ' ');
         }
         else if (_mesa_strcmp (id, "__FILE__") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, e->state->file);
            slang_string_pushc (e->output, ' ');
         }
         else if (_mesa_strcmp (id, "__VERSION__") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, e->state->version);
            slang_string_pushc (e->output, ' ');
         }
#if FEATURE_es2_glsl
         else if (_mesa_strcmp (id, "GL_ES") == 0 ||
                  _mesa_strcmp (id, "GL_FRAGMENT_PRECISION_HIGH") == 0) {
            slang_string_pushc (e->output, ' ');
            slang_string_pushi (e->output, '1');
            slang_string_pushc (e->output, ' ');
         }
#endif
         else {
            pp_symbol *symbol;

            /* The list of symbols from <symbols> take precedence over the list from <state>.
             * Note that in some cases this is the same list so avoid double look-up. */
            symbol = pp_symbols_find (symbols, id);
            if (symbol == NULL && symbols != &e->state->symbols)
               symbol = pp_symbols_find (&e->state->symbols, id);

            /* If the symbol was found, recursively expand its definition. */
            if (symbol != NULL) {
               if (!expand_symbol (e, symbol)) {
                  slang_string_free (&buffer);
                  return GL_FALSE;
               }
            }
            else {
               slang_string_push (e->output, &buffer);
            }
         }
         slang_string_free (&buffer);
      }
      else if (IS_WHITE(*e->input)) {
         slang_string_pushc (e->output, *e->input++);
      }
      else {
         while (!IS_WHITE(*e->input) && !IS_NULL(*e->input) && !IS_FIRST_ID_CHAR(*e->input))
            slang_string_pushc (e->output, *e->input++);
      }
   }
   return GL_TRUE;
}

static GLboolean
parse_if (slang_string *output, const byte *prod, GLuint *pi, GLint *result, pp_state *state,
          grammar eid)
{
   const char *text;
   GLuint len;

   text = (const char *) (&prod[*pi]);
   len = _mesa_strlen (text);

   if (state->cond.top->effective) {
      slang_string expr;
      GLuint count;
      GLint results[2];
      expand_state es;

      /* Expand the expression. */
      slang_string_init (&expr);
      es.output = &expr;
      es.input = text;
      es.state = state;
      if (!expand (&es, &state->symbols))
         return GL_FALSE;

      /* Execute the expression. */
      count = execute_expressions (output, eid, (const byte *) (slang_string_cstr (&expr)),
                                   results, state->elog);
      slang_string_free (&expr);
      if (count != 1)
         return GL_FALSE;
      *result = results[0];
   }
   else {
      /* The directive is dead. */
      *result = 0;
   }

   *pi += len + 1;
   return GL_TRUE;
}

#define ESCAPE_TOKEN 0

#define TOKEN_END       0
#define TOKEN_DEFINE    1
#define TOKEN_UNDEF     2
#define TOKEN_IF        3
#define TOKEN_ELSE      4
#define TOKEN_ELIF      5
#define TOKEN_ENDIF     6
#define TOKEN_ERROR     7
#define TOKEN_PRAGMA    8
#define TOKEN_EXTENSION 9
#define TOKEN_LINE      10

#define PARAM_END       0
#define PARAM_PARAMETER 1

#define BEHAVIOR_REQUIRE 1
#define BEHAVIOR_ENABLE  2
#define BEHAVIOR_WARN    3
#define BEHAVIOR_DISABLE 4

#define PRAGMA_NO_PARAM  0
#define PRAGMA_PARAM     1


static GLboolean
preprocess_source (slang_string *output, const char *source,
                   grammar pid, grammar eid,
                   slang_info_log *elog,
                   const struct gl_extensions *extensions)
{
   static const char *predefined[] = {
      "__FILE__",
      "__LINE__",
      "__VERSION__",
#if FEATURE_es2_glsl
      "GL_ES",
      "GL_FRAGMENT_PRECISION_HIGH",
#endif
      NULL
   };
   byte *prod;
   GLuint size, i;
   pp_state state;

   if (!grammar_fast_check (pid, (const byte *) (source), &prod, &size, 65536)) {
      grammar_error_to_log (elog);
      return GL_FALSE;
   }

   pp_state_init (&state, elog, extensions);

   /* add the predefined symbols to the symbol table */
   for (i = 0; predefined[i]; i++) {
      pp_symbol *symbol = NULL;
      symbol = pp_symbols_push(&state.symbols);
      assert(symbol);
      slang_string_pushs(&symbol->name,
                         predefined[i], _mesa_strlen(predefined[i]));
   }

   i = 0;
   while (i < size) {
      if (prod[i] != ESCAPE_TOKEN) {
         if (state.cond.top->effective) {
            slang_string input;
            expand_state es;

            /* Eat only one line of source code to expand it.
             * FIXME: This approach has one drawback. If a macro with parameters spans across
             *        multiple lines, the preprocessor will raise an error. */
            slang_string_init (&input);
            while (prod[i] != '\0' && prod[i] != '\n')
               slang_string_pushc (&input, prod[i++]);
            if (prod[i] != '\0')
               slang_string_pushc (&input, prod[i++]);

            /* Increment line number. */
            state.line++;

            es.output = output;
            es.input = slang_string_cstr (&input);
            es.state = &state;
            if (!expand (&es, &state.symbols))
               goto error;

            slang_string_free (&input);
         }
         else {
            /* Condition stack is disabled - keep track on line numbers and output only newlines. */
            if (prod[i] == '\n') {
               state.line++;
               /*pp_annotate (output, "%c", prod[i]);*/
            }
            else {
               /*pp_annotate (output, "%c", prod[i]);*/
            }
            i++;
         }
      }
      else {
         const char *id;
         GLuint idlen;
         GLubyte token;

         i++;
         token = prod[i++];
         switch (token) {

         case TOKEN_END:
            /* End of source string.
               * Check if all #ifs have been terminated by matching #endifs.
               * On condition stack there should be only the global condition context. */
            if (state.cond.top->endif_required) {
               slang_info_log_error (elog, "end of source without matching #endif.");
               return GL_FALSE;
            }
            break;

         case TOKEN_DEFINE:
            {
               pp_symbol *symbol = NULL;

               /* Parse macro name. */
               id = (const char *) (&prod[i]);
               idlen = _mesa_strlen (id);
               if (state.cond.top->effective) {
                  pp_annotate (output, "// #define %s(", id);

                  /* If the symbol is already defined, override it. */
                  symbol = pp_symbols_find (&state.symbols, id);
                  if (symbol == NULL) {
                     symbol = pp_symbols_push (&state.symbols);
                     if (symbol == NULL)
                        goto error;
                     slang_string_pushs (&symbol->name, id, idlen);
                  }
                  else {
                     pp_symbol_reset (symbol);
                  }
               }
               i += idlen + 1;

               /* Parse optional macro parameters. */
               while (prod[i++] != PARAM_END) {
                  if (state.cond.top->effective) {
                     pp_symbol *param;

                     id = (const char *) (&prod[i]);
                     idlen = _mesa_strlen (id);
                     pp_annotate (output, "%s, ", id);
                     param = pp_symbols_push (&symbol->parameters);
                     if (param == NULL)
                        goto error;
                     slang_string_pushs (&param->name, id, idlen);
                  }
                  i += idlen + 1;
               }

               /* Parse macro replacement. */
               id = (const char *) (&prod[i]);
               idlen = _mesa_strlen (id);
               if (state.cond.top->effective) {
                  pp_annotate (output, ") %s", id);
                  slang_string_pushs (&symbol->replacement, id, idlen);
               }
               i += idlen + 1;
            }
            break;

         case TOKEN_UNDEF:
            id = (const char *) (&prod[i]);
            i += _mesa_strlen (id) + 1;
            if (state.cond.top->effective) {
               pp_symbol *symbol;

               pp_annotate (output, "// #undef %s", id);
               /* Try to find symbol with given name and remove it. */
               symbol = pp_symbols_find (&state.symbols, id);
               if (symbol != NULL)
                  if (!pp_symbols_erase (&state.symbols, symbol))
                     goto error;
            }
            break;

         case TOKEN_IF:
            {
               GLint result;

               /* Parse #if expression end execute it. */
               pp_annotate (output, "// #if ");
               if (!parse_if (output, prod, &i, &result, &state, eid))
                  goto error;

               /* Push new condition on the stack. */
               if (!pp_cond_stack_push (&state.cond, state.elog))
                  goto error;
               state.cond.top->current = result ? GL_TRUE : GL_FALSE;
               state.cond.top->else_allowed = GL_TRUE;
               state.cond.top->endif_required = GL_TRUE;
               pp_cond_stack_reevaluate (&state.cond);
            }
            break;

         case TOKEN_ELSE:
            /* Check if #else is alloved here. */
            if (!state.cond.top->else_allowed) {
               slang_info_log_error (elog, "#else without matching #if.");
               goto error;
            }

            /* Negate current condition and reevaluate it. */
            state.cond.top->current = !state.cond.top->current;
            state.cond.top->else_allowed = GL_FALSE;
            pp_cond_stack_reevaluate (&state.cond);
            if (state.cond.top->effective)
               pp_annotate (output, "// #else");
            break;

         case TOKEN_ELIF:
            /* Check if #elif is alloved here. */
            if (!state.cond.top->else_allowed) {
               slang_info_log_error (elog, "#elif without matching #if.");
               goto error;
            }

            /* Negate current condition and reevaluate it. */
            state.cond.top->current = !state.cond.top->current;
            pp_cond_stack_reevaluate (&state.cond);

            if (state.cond.top->effective)
               pp_annotate (output, "// #elif ");

            {
               GLint result;

               /* Parse #elif expression end execute it. */
               if (!parse_if (output, prod, &i, &result, &state, eid))
                  goto error;

               /* Update current condition and reevaluate it. */
               state.cond.top->current = result ? GL_TRUE : GL_FALSE;
               pp_cond_stack_reevaluate (&state.cond);
            }
            break;

         case TOKEN_ENDIF:
            /* Check if #endif is alloved here. */
            if (!state.cond.top->endif_required) {
               slang_info_log_error (elog, "#endif without matching #if.");
               goto error;
            }

            /* Pop the condition off the stack. */
            state.cond.top++;
            if (state.cond.top->effective)
               pp_annotate (output, "// #endif");
            break;

         case TOKEN_EXTENSION:
            /* Parse the extension name. */
            id = (const char *) (&prod[i]);
            i += _mesa_strlen (id) + 1;
            if (state.cond.top->effective)
               pp_annotate (output, "// #extension %s: ", id);

            /* Parse and apply extension behavior. */
            if (state.cond.top->effective) {
               switch (prod[i++]) {

               case BEHAVIOR_REQUIRE:
                  pp_annotate (output, "require");
                  if (!pp_ext_set (&state.ext, id, GL_TRUE)) {
                     if (_mesa_strcmp (id, "all") == 0) {
                        slang_info_log_error (elog, "require: bad behavior for #extension all.");
                        goto error;
                     }
                     else {
                        slang_info_log_error (elog, "%s: required extension is not supported.", id);
                        goto error;
                     }
                  }
                  break;

               case BEHAVIOR_ENABLE:
                  pp_annotate (output, "enable");
                  if (!pp_ext_set (&state.ext, id, GL_TRUE)) {
                     if (_mesa_strcmp (id, "all") == 0) {
                        slang_info_log_error (elog, "enable: bad behavior for #extension all.");
                        goto error;
                     }
                     else {
                        slang_info_log_warning (elog, "%s: enabled extension is not supported.", id);
                     }
                  }
                  break;

               case BEHAVIOR_WARN:
                  pp_annotate (output, "warn");
                  if (!pp_ext_set (&state.ext, id, GL_TRUE)) {
                     if (_mesa_strcmp (id, "all") != 0) {
                        slang_info_log_warning (elog, "%s: enabled extension is not supported.", id);
                     }
                  }
                  break;

               case BEHAVIOR_DISABLE:
                  pp_annotate (output, "disable");
                  if (!pp_ext_set (&state.ext, id, GL_FALSE)) {
                     if (_mesa_strcmp (id, "all") == 0) {
                        pp_ext_disable_all (&state.ext);
                     }
                     else {
                        slang_info_log_warning (elog, "%s: disabled extension is not supported.", id);
                     }
                  }
                  break;

               default:
                  assert (0);
               }
            }
            break;

         case TOKEN_PRAGMA:
            {
               GLint have_param;
               const char *pragma, *param;

               pragma = (const char *) (&prod[i]);
               i += _mesa_strlen(pragma) + 1;
               have_param = (prod[i++] == PRAGMA_PARAM);
               if (have_param) {
                  param = (const char *) (&prod[i]);
                  i += _mesa_strlen(param) + 1;
               }
               else {
                  param = NULL;
               }
               pp_pragma(pragma, param);
            }
            break;

         case TOKEN_LINE:
            id = (const char *) (&prod[i]);
            i += _mesa_strlen (id) + 1;

            if (state.cond.top->effective) {
               slang_string buffer;
               GLuint count;
               GLint results[2];
               expand_state es;

               slang_string_init (&buffer);
               state.line++;
               es.output = &buffer;
               es.input = id;
               es.state = &state;
               if (!expand (&es, &state.symbols))
                  goto error;

               pp_annotate (output, "// #line ");
               count = execute_expressions (output, eid,
                                             (const byte *) (slang_string_cstr (&buffer)),
                                             results, state.elog);
               slang_string_free (&buffer);
               if (count == 0)
                  goto error;

               state.line = results[0] - 1;
               if (count == 2)
                  state.file = results[1];
            }
            break;
         }
      }
   }

   /* Check for missing #endifs. */
   if (state.cond.top->endif_required) {
      slang_info_log_error (elog, "#endif expected but end of source found.");
      goto error;
   }

   grammar_alloc_free(prod);
   pp_state_free (&state);
   return GL_TRUE;

error:
   grammar_alloc_free(prod);
   pp_state_free (&state);
   return GL_FALSE;
}


/**
 * Run preprocessor on source code.
 * \param extensions  indicates which GL extensions are enabled
 * \param output  the post-process results
 * \param input  the input text
 * \param elog  log to record warnings, errors
 * \return GL_TRUE for success, GL_FALSE for error
 */
GLboolean
_slang_preprocess_directives(slang_string *output,
                             const char *input,
                             slang_info_log *elog,
                             const struct gl_extensions *extensions)
{
   grammar pid, eid;
   GLboolean success;

   pid = grammar_load_from_text ((const byte *) (slang_pp_directives_syn));
   if (pid == 0) {
      grammar_error_to_log (elog);
      return GL_FALSE;
   }
   eid = grammar_load_from_text ((const byte *) (slang_pp_expression_syn));
   if (eid == 0) {
      grammar_error_to_log (elog);
      grammar_destroy (pid);
      return GL_FALSE;
   }
   success = preprocess_source (output, input, pid, eid, elog, extensions);
   grammar_destroy (eid);
   grammar_destroy (pid);
   return success;
}