2 * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at>
3 * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org>
5 * This file is part of Libav.
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.
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.
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
24 * simple arithmetic expression evaluator.
26 * see http://joe.hotchkiss.com/programming/eval/eval.html
33 typedef struct Parser {
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
50 static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) };
52 static const int8_t si_prefixes['z' - 'E' + 1] = {
75 double av_strtod(const char *numstr, char **tail)
79 d = strtod(numstr, &next);
80 /* if parsing succeeded, check for and interpret postfixes */
82 if (*next >= 'E' && *next <= 'z') {
83 int e= si_prefixes[*next - 'E'];
100 /* if requested, fill in tail with the position after the last parsed
107 #define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
109 static int strmatch(const char *s, const char *prefix)
112 for (i=0; prefix[i]; i++) {
113 if (prefix[i] != s[i]) return 0;
115 /* return 1 only if the s identifier is terminated */
116 return !IS_IDENTIFIER_CHAR(s[i]);
121 e_value, e_const, e_func0, e_func1, e_func2,
122 e_squish, e_gauss, e_ld, e_isnan,
123 e_mod, e_max, e_min, e_eq, e_gt, e_gte,
124 e_pow, e_mul, e_div, e_add,
125 e_last, e_st, e_while, e_floor, e_ceil, e_trunc,
128 double value; // is sign in other types
131 double (*func0)(double);
132 double (*func1)(void *, double);
133 double (*func2)(void *, double, double);
135 struct AVExpr *param[2];
138 static double eval_expr(Parser *p, AVExpr *e)
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;
157 while (eval_expr(p, e->param[0]))
158 d=eval_expr(p, e->param[1]);
162 double d = eval_expr(p, e->param[0]);
163 double d2 = eval_expr(p, e->param[1]);
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);
183 static int parse_expr(AVExpr **e, Parser *p);
185 void av_expr_free(AVExpr *e)
188 av_expr_free(e->param[0]);
189 av_expr_free(e->param[1]);
193 static int parse_primary(AVExpr **e, Parser *p)
195 AVExpr *d = av_mallocz(sizeof(AVExpr));
196 char *next = p->s, *s0 = p->s;
200 return AVERROR(ENOMEM);
203 d->value = av_strtod(p->s, &next);
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]);
217 d->a.const_index = i;
223 p->s= strchr(p->s, '(');
225 av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
228 return AVERROR(EINVAL);
231 if (*next == '(') { // special case do-nothing
233 if ((ret = parse_expr(&d, p)) < 0)
235 if (p->s[0] != ')') {
236 av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
238 return AVERROR(EINVAL);
244 if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
250 parse_expr(&d->param[1], p);
252 if (p->s[0] != ')') {
253 av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
255 return AVERROR(EINVAL);
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_gt; }
281 else if (strmatch(next, "lt" )) { AVExpr *tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }
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;
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];
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];
310 av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
312 return AVERROR(EINVAL);
319 static AVExpr *new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
321 AVExpr *e = av_mallocz(sizeof(AVExpr));
331 static int parse_pow(AVExpr **e, Parser *p, int *sign)
333 *sign= (*p->s == '+') - (*p->s == '-');
335 return parse_primary(e, p);
338 static int parse_factor(AVExpr **e, Parser *p)
340 int sign, sign2, ret;
341 AVExpr *e0, *e1, *e2;
342 if ((ret = parse_pow(&e0, p, &sign)) < 0)
347 if ((ret = parse_pow(&e2, p, &sign2)) < 0) {
351 e0 = new_eval_expr(e_pow, 1, e1, e2);
355 return AVERROR(ENOMEM);
357 if (e0->param[1]) e0->param[1]->value *= (sign2|1);
359 if (e0) e0->value *= (sign|1);
365 static int parse_term(AVExpr **e, Parser *p)
368 AVExpr *e0, *e1, *e2;
369 if ((ret = parse_factor(&e0, p)) < 0)
371 while (p->s[0]=='*' || p->s[0]=='/') {
374 if ((ret = parse_factor(&e2, p)) < 0) {
378 e0 = new_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
382 return AVERROR(ENOMEM);
389 static int parse_subexpr(AVExpr **e, Parser *p)
392 AVExpr *e0, *e1, *e2;
393 if ((ret = parse_term(&e0, p)) < 0)
395 while (*p->s == '+' || *p->s == '-') {
397 if ((ret = parse_term(&e2, p)) < 0) {
401 e0 = new_eval_expr(e_add, 1, e1, e2);
405 return AVERROR(ENOMEM);
413 static int parse_expr(AVExpr **e, Parser *p)
416 AVExpr *e0, *e1, *e2;
417 if (p->stack_index <= 0) //protect against stack overflows
418 return AVERROR(EINVAL);
421 if ((ret = parse_subexpr(&e0, p)) < 0)
423 while (*p->s == ';') {
426 if ((ret = parse_subexpr(&e2, p)) < 0) {
430 e0 = new_eval_expr(e_last, 1, e1, e2);
434 return AVERROR(ENOMEM);
443 static int verify_expr(AVExpr *e)
448 case e_const: return 1;
460 return verify_expr(e->param[0]);
461 default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);
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)
473 char *w = av_malloc(strlen(s) + 1);
479 return AVERROR(ENOMEM);
482 if (!isspace(*s++)) *wp++ = s[-1];
488 p.const_names = const_names;
490 p.func1_names = func1_names;
492 p.func2_names = func2_names;
493 p.log_offset = log_offset;
496 if ((ret = parse_expr(&e, &p)) < 0)
500 av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
501 ret = AVERROR(EINVAL);
504 if (!verify_expr(e)) {
506 ret = AVERROR(EINVAL);
515 double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
519 p.const_values = const_values;
521 return eval_expr(&p, e);
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)
531 int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
537 *d = av_expr_eval(e, const_values, opaque);
539 return isnan(*d) ? AVERROR(EINVAL) : 0;
546 static double const_values[] = {
552 static const char *const_names[] = {
558 int main(int argc, char **argv)
562 const char **expr, *exprs[] = {
568 "1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)",
589 "bar + PI + E + 100f*2 + foo",
590 "13k + 12f - foo(1, 2)",
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)",
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)",
600 "st(0, 1); while(lte(ld(0),100), st(1, ld(1)+ld(0)); st(0, ld(0)+1))",
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);
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);
635 if (argc > 1 && !strcmp(argv[1], "-t")) {
636 for (i = 0; i < 1050; i++) {
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");