eval.c
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1 /*
2  * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
3  * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
4  *
5  * This file is part of Libav.
6  *
7  * Libav is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * Libav is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with Libav; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
29 #include "avutil.h"
30 #include "eval.h"
31 #include "log.h"
32 
33 typedef struct Parser {
34  const AVClass *class;
36  char *s;
37  const double *const_values;
38  const char * const *const_names; // NULL terminated
39  double (* const *funcs1)(void *, double a); // NULL terminated
40  const char * const *func1_names; // NULL terminated
41  double (* const *funcs2)(void *, double a, double b); // NULL terminated
42  const char * const *func2_names; // NULL terminated
43  void *opaque;
45  void *log_ctx;
46 #define VARS 10
47  double var[VARS];
48 } Parser;
49 
50 static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
51 
52 static const int8_t si_prefixes['z' - 'E' + 1] = {
53  ['y'-'E']= -24,
54  ['z'-'E']= -21,
55  ['a'-'E']= -18,
56  ['f'-'E']= -15,
57  ['p'-'E']= -12,
58  ['n'-'E']= - 9,
59  ['u'-'E']= - 6,
60  ['m'-'E']= - 3,
61  ['c'-'E']= - 2,
62  ['d'-'E']= - 1,
63  ['h'-'E']= 2,
64  ['k'-'E']= 3,
65  ['K'-'E']= 3,
66  ['M'-'E']= 6,
67  ['G'-'E']= 9,
68  ['T'-'E']= 12,
69  ['P'-'E']= 15,
70  ['E'-'E']= 18,
71  ['Z'-'E']= 21,
72  ['Y'-'E']= 24,
73 };
74 
75 double av_strtod(const char *numstr, char **tail)
76 {
77  double d;
78  char *next;
79  d = strtod(numstr, &next);
80  /* if parsing succeeded, check for and interpret postfixes */
81  if (next!=numstr) {
82  if (*next >= 'E' && *next <= 'z') {
83  int e= si_prefixes[*next - 'E'];
84  if (e) {
85  if (next[1] == 'i') {
86  d*= pow( 2, e/0.3);
87  next+=2;
88  } else {
89  d*= pow(10, e);
90  next++;
91  }
92  }
93  }
94 
95  if (*next=='B') {
96  d*=8;
97  next++;
98  }
99  }
100  /* if requested, fill in tail with the position after the last parsed
101  character */
102  if (tail)
103  *tail = next;
104  return d;
105 }
106 
107 #define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
108 
109 static int strmatch(const char *s, const char *prefix)
110 {
111  int i;
112  for (i=0; prefix[i]; i++) {
113  if (prefix[i] != s[i]) return 0;
114  }
115  /* return 1 only if the s identifier is terminated */
116  return !IS_IDENTIFIER_CHAR(s[i]);
117 }
118 
119 struct AVExpr {
120  enum {
127  } type;
128  double value; // is sign in other types
129  union {
131  double (*func0)(double);
132  double (*func1)(void *, double);
133  double (*func2)(void *, double, double);
134  } a;
135  struct AVExpr *param[2];
136 };
137 
138 static double eval_expr(Parser *p, AVExpr *e)
139 {
140  switch (e->type) {
141  case e_value: return e->value;
142  case e_const: return e->value * p->const_values[e->a.const_index];
143  case e_func0: return e->value * e->a.func0(eval_expr(p, e->param[0]));
144  case e_func1: return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
145  case e_func2: return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
146  case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
147  case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
148  case e_ld: return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
149  case e_isnan: return e->value * !!isnan(eval_expr(p, e->param[0]));
150  case e_floor: return e->value * floor(eval_expr(p, e->param[0]));
151  case e_ceil : return e->value * ceil (eval_expr(p, e->param[0]));
152  case e_trunc: return e->value * trunc(eval_expr(p, e->param[0]));
153  case e_sqrt: return e->value * sqrt (eval_expr(p, e->param[0]));
154  case e_not: return e->value * eval_expr(p, e->param[0]) == 0;
155  case e_while: {
156  double d = NAN;
157  while (eval_expr(p, e->param[0]))
158  d=eval_expr(p, e->param[1]);
159  return d;
160  }
161  default: {
162  double d = eval_expr(p, e->param[0]);
163  double d2 = eval_expr(p, e->param[1]);
164  switch (e->type) {
165  case e_mod: return e->value * (d - floor(d/d2)*d2);
166  case e_max: return e->value * (d > d2 ? d : d2);
167  case e_min: return e->value * (d < d2 ? d : d2);
168  case e_eq: return e->value * (d == d2 ? 1.0 : 0.0);
169  case e_gt: return e->value * (d > d2 ? 1.0 : 0.0);
170  case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
171  case e_pow: return e->value * pow(d, d2);
172  case e_mul: return e->value * (d * d2);
173  case e_div: return e->value * (d / d2);
174  case e_add: return e->value * (d + d2);
175  case e_last:return e->value * d2;
176  case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
177  }
178  }
179  }
180  return NAN;
181 }
182 
183 static int parse_expr(AVExpr **e, Parser *p);
184 
186 {
187  if (!e) return;
188  av_expr_free(e->param[0]);
189  av_expr_free(e->param[1]);
190  av_freep(&e);
191 }
192 
193 static int parse_primary(AVExpr **e, Parser *p)
194 {
195  AVExpr *d = av_mallocz(sizeof(AVExpr));
196  char *next = p->s, *s0 = p->s;
197  int ret, i;
198 
199  if (!d)
200  return AVERROR(ENOMEM);
201 
202  /* number */
203  d->value = av_strtod(p->s, &next);
204  if (next != p->s) {
205  d->type = e_value;
206  p->s= next;
207  *e = d;
208  return 0;
209  }
210  d->value = 1;
211 
212  /* named constants */
213  for (i=0; p->const_names && p->const_names[i]; i++) {
214  if (strmatch(p->s, p->const_names[i])) {
215  p->s+= strlen(p->const_names[i]);
216  d->type = e_const;
217  d->a.const_index = i;
218  *e = d;
219  return 0;
220  }
221  }
222 
223  p->s= strchr(p->s, '(');
224  if (p->s==NULL) {
225  av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
226  p->s= next;
227  av_expr_free(d);
228  return AVERROR(EINVAL);
229  }
230  p->s++; // "("
231  if (*next == '(') { // special case do-nothing
232  av_freep(&d);
233  if ((ret = parse_expr(&d, p)) < 0)
234  return ret;
235  if (p->s[0] != ')') {
236  av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
237  av_expr_free(d);
238  return AVERROR(EINVAL);
239  }
240  p->s++; // ")"
241  *e = d;
242  return 0;
243  }
244  if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
245  av_expr_free(d);
246  return ret;
247  }
248  if (p->s[0]== ',') {
249  p->s++; // ","
250  parse_expr(&d->param[1], p);
251  }
252  if (p->s[0] != ')') {
253  av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
254  av_expr_free(d);
255  return AVERROR(EINVAL);
256  }
257  p->s++; // ")"
258 
259  d->type = e_func0;
260  if (strmatch(next, "sinh" )) d->a.func0 = sinh;
261  else if (strmatch(next, "cosh" )) d->a.func0 = cosh;
262  else if (strmatch(next, "tanh" )) d->a.func0 = tanh;
263  else if (strmatch(next, "sin" )) d->a.func0 = sin;
264  else if (strmatch(next, "cos" )) d->a.func0 = cos;
265  else if (strmatch(next, "tan" )) d->a.func0 = tan;
266  else if (strmatch(next, "atan" )) d->a.func0 = atan;
267  else if (strmatch(next, "asin" )) d->a.func0 = asin;
268  else if (strmatch(next, "acos" )) d->a.func0 = acos;
269  else if (strmatch(next, "exp" )) d->a.func0 = exp;
270  else if (strmatch(next, "log" )) d->a.func0 = log;
271  else if (strmatch(next, "abs" )) d->a.func0 = fabs;
272  else if (strmatch(next, "squish")) d->type = e_squish;
273  else if (strmatch(next, "gauss" )) d->type = e_gauss;
274  else if (strmatch(next, "mod" )) d->type = e_mod;
275  else if (strmatch(next, "max" )) d->type = e_max;
276  else if (strmatch(next, "min" )) d->type = e_min;
277  else if (strmatch(next, "eq" )) d->type = e_eq;
278  else if (strmatch(next, "gte" )) d->type = e_gte;
279  else if (strmatch(next, "gt" )) d->type = e_gt;
280  else if (strmatch(next, "lte" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
281  else if (strmatch(next, "lt" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }
282  else if (strmatch(next, "ld" )) d->type = e_ld;
283  else if (strmatch(next, "isnan" )) d->type = e_isnan;
284  else if (strmatch(next, "st" )) d->type = e_st;
285  else if (strmatch(next, "while" )) d->type = e_while;
286  else if (strmatch(next, "floor" )) d->type = e_floor;
287  else if (strmatch(next, "ceil" )) d->type = e_ceil;
288  else if (strmatch(next, "trunc" )) d->type = e_trunc;
289  else if (strmatch(next, "sqrt" )) d->type = e_sqrt;
290  else if (strmatch(next, "not" )) d->type = e_not;
291  else {
292  for (i=0; p->func1_names && p->func1_names[i]; i++) {
293  if (strmatch(next, p->func1_names[i])) {
294  d->a.func1 = p->funcs1[i];
295  d->type = e_func1;
296  *e = d;
297  return 0;
298  }
299  }
300 
301  for (i=0; p->func2_names && p->func2_names[i]; i++) {
302  if (strmatch(next, p->func2_names[i])) {
303  d->a.func2 = p->funcs2[i];
304  d->type = e_func2;
305  *e = d;
306  return 0;
307  }
308  }
309 
310  av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
311  av_expr_free(d);
312  return AVERROR(EINVAL);
313  }
314 
315  *e = d;
316  return 0;
317 }
318 
319 static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
320 {
321  AVExpr *e = av_mallocz(sizeof(AVExpr));
322  if (!e)
323  return NULL;
324  e->type =type ;
325  e->value =value ;
326  e->param[0] =p0 ;
327  e->param[1] =p1 ;
328  return e;
329 }
330 
331 static int parse_pow(AVExpr **e, Parser *p, int *sign)
332 {
333  *sign= (*p->s == '+') - (*p->s == '-');
334  p->s += *sign&1;
335  return parse_primary(e, p);
336 }
337 
338 static int parse_factor(AVExpr **e, Parser *p)
339 {
340  int sign, sign2, ret;
341  AVExpr *e0, *e1, *e2;
342  if ((ret = parse_pow(&e0, p, &sign)) < 0)
343  return ret;
344  while(p->s[0]=='^'){
345  e1 = e0;
346  p->s++;
347  if ((ret = parse_pow(&e2, p, &sign2)) < 0) {
348  av_expr_free(e1);
349  return ret;
350  }
351  e0 = new_eval_expr(e_pow, 1, e1, e2);
352  if (!e0) {
353  av_expr_free(e1);
354  av_expr_free(e2);
355  return AVERROR(ENOMEM);
356  }
357  if (e0->param[1]) e0->param[1]->value *= (sign2|1);
358  }
359  if (e0) e0->value *= (sign|1);
360 
361  *e = e0;
362  return 0;
363 }
364 
365 static int parse_term(AVExpr **e, Parser *p)
366 {
367  int ret;
368  AVExpr *e0, *e1, *e2;
369  if ((ret = parse_factor(&e0, p)) < 0)
370  return ret;
371  while (p->s[0]=='*' || p->s[0]=='/') {
372  int c= *p->s++;
373  e1 = e0;
374  if ((ret = parse_factor(&e2, p)) < 0) {
375  av_expr_free(e1);
376  return ret;
377  }
378  e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
379  if (!e0) {
380  av_expr_free(e1);
381  av_expr_free(e2);
382  return AVERROR(ENOMEM);
383  }
384  }
385  *e = e0;
386  return 0;
387 }
388 
389 static int parse_subexpr(AVExpr **e, Parser *p)
390 {
391  int ret;
392  AVExpr *e0, *e1, *e2;
393  if ((ret = parse_term(&e0, p)) < 0)
394  return ret;
395  while (*p->s == '+' || *p->s == '-') {
396  e1 = e0;
397  if ((ret = parse_term(&e2, p)) < 0) {
398  av_expr_free(e1);
399  return ret;
400  }
401  e0 = new_eval_expr(e_add, 1, e1, e2);
402  if (!e0) {
403  av_expr_free(e1);
404  av_expr_free(e2);
405  return AVERROR(ENOMEM);
406  }
407  };
408 
409  *e = e0;
410  return 0;
411 }
412 
413 static int parse_expr(AVExpr **e, Parser *p)
414 {
415  int ret;
416  AVExpr *e0, *e1, *e2;
417  if (p->stack_index <= 0) //protect against stack overflows
418  return AVERROR(EINVAL);
419  p->stack_index--;
420 
421  if ((ret = parse_subexpr(&e0, p)) < 0)
422  return ret;
423  while (*p->s == ';') {
424  p->s++;
425  e1 = e0;
426  if ((ret = parse_subexpr(&e2, p)) < 0) {
427  av_expr_free(e1);
428  return ret;
429  }
430  e0 = new_eval_expr(e_last, 1, e1, e2);
431  if (!e0) {
432  av_expr_free(e1);
433  av_expr_free(e2);
434  return AVERROR(ENOMEM);
435  }
436  };
437 
438  p->stack_index++;
439  *e = e0;
440  return 0;
441 }
442 
443 static int verify_expr(AVExpr *e)
444 {
445  if (!e) return 0;
446  switch (e->type) {
447  case e_value:
448  case e_const: return 1;
449  case e_func0:
450  case e_func1:
451  case e_squish:
452  case e_ld:
453  case e_gauss:
454  case e_isnan:
455  case e_floor:
456  case e_ceil:
457  case e_trunc:
458  case e_sqrt:
459  case e_not:
460  return verify_expr(e->param[0]);
461  default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
462  }
463 }
464 
465 int av_expr_parse(AVExpr **expr, const char *s,
466  const char * const *const_names,
467  const char * const *func1_names, double (* const *funcs1)(void *, double),
468  const char * const *func2_names, double (* const *funcs2)(void *, double, double),
469  int log_offset, void *log_ctx)
470 {
471  Parser p = { 0 };
472  AVExpr *e = NULL;
473  char *w = av_malloc(strlen(s) + 1);
474  char *wp = w;
475  const char *s0 = s;
476  int ret = 0;
477 
478  if (!w)
479  return AVERROR(ENOMEM);
480 
481  while (*s)
482  if (!isspace(*s++)) *wp++ = s[-1];
483  *wp++ = 0;
484 
485  p.class = &class;
486  p.stack_index=100;
487  p.s= w;
489  p.funcs1 = funcs1;
490  p.func1_names = func1_names;
491  p.funcs2 = funcs2;
492  p.func2_names = func2_names;
493  p.log_offset = log_offset;
494  p.log_ctx = log_ctx;
495 
496  if ((ret = parse_expr(&e, &p)) < 0)
497  goto end;
498  if (*p.s) {
499  av_expr_free(e);
500  av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
501  ret = AVERROR(EINVAL);
502  goto end;
503  }
504  if (!verify_expr(e)) {
505  av_expr_free(e);
506  ret = AVERROR(EINVAL);
507  goto end;
508  }
509  *expr = e;
510 end:
511  av_free(w);
512  return ret;
513 }
514 
515 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
516 {
517  Parser p = { 0 };
518 
520  p.opaque = opaque;
521  return eval_expr(&p, e);
522 }
523 
524 int av_expr_parse_and_eval(double *d, const char *s,
525  const char * const *const_names, const double *const_values,
526  const char * const *func1_names, double (* const *funcs1)(void *, double),
527  const char * const *func2_names, double (* const *funcs2)(void *, double, double),
528  void *opaque, int log_offset, void *log_ctx)
529 {
530  AVExpr *e = NULL;
531  int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
532 
533  if (ret < 0) {
534  *d = NAN;
535  return ret;
536  }
537  *d = av_expr_eval(e, const_values, opaque);
538  av_expr_free(e);
539  return isnan(*d) ? AVERROR(EINVAL) : 0;
540 }
541 
542 #ifdef TEST
543 #undef printf
544 #include <string.h>
545 
546 static double const_values[] = {
547  M_PI,
548  M_E,
549  0
550 };
551 
552 static const char *const_names[] = {
553  "PI",
554  "E",
555  0
556 };
557 
558 int main(int argc, char **argv)
559 {
560  int i;
561  double d;
562  const char **expr, *exprs[] = {
563  "",
564  "1;2",
565  "-20",
566  "-PI",
567  "+PI",
568  "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
569  "80G/80Gi",
570  "1k",
571  "1Gi",
572  "1gi",
573  "1GiFoo",
574  "1k+1k",
575  "1Gi*3foo",
576  "foo",
577  "foo(",
578  "foo()",
579  "foo)",
580  "sin",
581  "sin(",
582  "sin()",
583  "sin)",
584  "sin 10",
585  "sin(1,2,3)",
586  "sin(1 )",
587  "1",
588  "1foo",
589  "bar + PI + E + 100f*2 + foo",
590  "13k + 12f - foo(1, 2)",
591  "1gi",
592  "1Gi",
593  "st(0, 123)",
594  "st(1, 123); ld(1)",
595  /* compute 1+2+...+N */
596  "st(0, 1); while(lte(ld(0), 100), st(1, ld(1)+ld(0));st(0, ld(0)+1)); ld(1)",
597  /* compute Fib(N) */
598  "st(1, 1); st(2, 2); st(0, 1); while(lte(ld(0),10), st(3, ld(1)+ld(2)); st(1, ld(2)); st(2, ld(3)); st(0, ld(0)+1)); ld(3)",
599  "while(0, 10)",
600  "st(0, 1); while(lte(ld(0),100), st(1, ld(1)+ld(0)); st(0, ld(0)+1))",
601  "isnan(1)",
602  "isnan(NAN)",
603  "floor(NAN)",
604  "floor(123.123)",
605  "floor(-123.123)",
606  "trunc(123.123)",
607  "trunc(-123.123)",
608  "ceil(123.123)",
609  "ceil(-123.123)",
610  "sqrt(1764)",
611  "isnan(sqrt(-1))",
612  "not(1)",
613  "not(NAN)",
614  "not(0)",
615  NULL
616  };
617 
618  for (expr = exprs; *expr; expr++) {
619  printf("Evaluating '%s'\n", *expr);
620  av_expr_parse_and_eval(&d, *expr,
621  const_names, const_values,
622  NULL, NULL, NULL, NULL, NULL, 0, NULL);
623  printf("'%s' -> %f\n\n", *expr, d);
624  }
625 
626  av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
627  const_names, const_values,
628  NULL, NULL, NULL, NULL, NULL, 0, NULL);
629  printf("%f == 12.7\n", d);
630  av_expr_parse_and_eval(&d, "80G/80Gi",
631  const_names, const_values,
632  NULL, NULL, NULL, NULL, NULL, 0, NULL);
633  printf("%f == 0.931322575\n", d);
634 
635  if (argc > 1 && !strcmp(argv[1], "-t")) {
636  for (i = 0; i < 1050; i++) {
637  START_TIMER;
638  av_expr_parse_and_eval(&d, "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
639  const_names, const_values,
640  NULL, NULL, NULL, NULL, NULL, 0, NULL);
641  STOP_TIMER("av_expr_parse_and_eval");
642  }
643  }
644 
645  return 0;
646 }
647 #endif