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/libavutil/eval.c

http://github.com/FFmpeg/FFmpeg
C | 792 lines | 705 code | 52 blank | 35 comment | 248 complexity | d02ba5c3a40fe2cf606e403259246480 MD5 | raw file
  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 FFmpeg.
  6 *
  7 * FFmpeg 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 * FFmpeg 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 FFmpeg; if not, write to the Free Software
 19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 20 */
 21
 22/**
 23 * @file
 24 * simple arithmetic expression evaluator.
 25 *
 26 * see http://joe.hotchkiss.com/programming/eval/eval.html
 27 */
 28
 29#include <float.h>
 30#include "attributes.h"
 31#include "avutil.h"
 32#include "common.h"
 33#include "eval.h"
 34#include "ffmath.h"
 35#include "internal.h"
 36#include "log.h"
 37#include "mathematics.h"
 38#include "time.h"
 39#include "avstring.h"
 40#include "timer.h"
 41#include "reverse.h"
 42
 43typedef struct Parser {
 44    const AVClass *class;
 45    int stack_index;
 46    char *s;
 47    const double *const_values;
 48    const char * const *const_names;          // NULL terminated
 49    double (* const *funcs1)(void *, double a);           // NULL terminated
 50    const char * const *func1_names;          // NULL terminated
 51    double (* const *funcs2)(void *, double a, double b); // NULL terminated
 52    const char * const *func2_names;          // NULL terminated
 53    void *opaque;
 54    int log_offset;
 55    void *log_ctx;
 56#define VARS 10
 57    double *var;
 58} Parser;
 59
 60static const AVClass eval_class = {
 61    .class_name                = "Eval",
 62    .item_name                 = av_default_item_name,
 63    .option                    = NULL,
 64    .version                   = LIBAVUTIL_VERSION_INT,
 65    .log_level_offset_offset   = offsetof(Parser, log_offset),
 66    .parent_log_context_offset = offsetof(Parser, log_ctx),
 67};
 68
 69static const struct {
 70    double bin_val;
 71    double dec_val;
 72    int8_t exp;
 73} si_prefixes['z' - 'E' + 1] = {
 74    ['y'-'E']= { 8.271806125530276749e-25, 1e-24, -24 },
 75    ['z'-'E']= { 8.4703294725430034e-22, 1e-21, -21 },
 76    ['a'-'E']= { 8.6736173798840355e-19, 1e-18, -18 },
 77    ['f'-'E']= { 8.8817841970012523e-16, 1e-15, -15 },
 78    ['p'-'E']= { 9.0949470177292824e-13, 1e-12, -12 },
 79    ['n'-'E']= { 9.3132257461547852e-10, 1e-9,  -9 },
 80    ['u'-'E']= { 9.5367431640625e-7, 1e-6, -6 },
 81    ['m'-'E']= { 9.765625e-4, 1e-3, -3 },
 82    ['c'-'E']= { 9.8431332023036951e-3, 1e-2, -2 },
 83    ['d'-'E']= { 9.921256574801246e-2, 1e-1, -1 },
 84    ['h'-'E']= { 1.0159366732596479e2, 1e2, 2 },
 85    ['k'-'E']= { 1.024e3, 1e3, 3 },
 86    ['K'-'E']= { 1.024e3, 1e3, 3 },
 87    ['M'-'E']= { 1.048576e6, 1e6, 6 },
 88    ['G'-'E']= { 1.073741824e9, 1e9, 9 },
 89    ['T'-'E']= { 1.099511627776e12, 1e12, 12 },
 90    ['P'-'E']= { 1.125899906842624e15, 1e15, 15 },
 91    ['E'-'E']= { 1.152921504606847e18, 1e18, 18 },
 92    ['Z'-'E']= { 1.1805916207174113e21, 1e21, 21 },
 93    ['Y'-'E']= { 1.2089258196146292e24, 1e24, 24 },
 94};
 95
 96static const struct {
 97    const char *name;
 98    double value;
 99} constants[] = {
100    { "E",   M_E   },
101    { "PI",  M_PI  },
102    { "PHI", M_PHI },
103    { "QP2LAMBDA", FF_QP2LAMBDA },
104};
105
106double av_strtod(const char *numstr, char **tail)
107{
108    double d;
109    char *next;
110    if(numstr[0]=='0' && (numstr[1]|0x20)=='x') {
111        d = strtoul(numstr, &next, 16);
112    } else
113        d = strtod(numstr, &next);
114    /* if parsing succeeded, check for and interpret postfixes */
115    if (next!=numstr) {
116        if (next[0] == 'd' && next[1] == 'B') {
117            /* treat dB as decibels instead of decibytes */
118            d = ff_exp10(d / 20);
119            next += 2;
120        } else if (*next >= 'E' && *next <= 'z') {
121            int e= si_prefixes[*next - 'E'].exp;
122            if (e) {
123                if (next[1] == 'i') {
124                    d*= si_prefixes[*next - 'E'].bin_val;
125                    next+=2;
126                } else {
127                    d*= si_prefixes[*next - 'E'].dec_val;
128                    next++;
129                }
130            }
131        }
132
133        if (*next=='B') {
134            d*=8;
135            next++;
136        }
137    }
138    /* if requested, fill in tail with the position after the last parsed
139       character */
140    if (tail)
141        *tail = next;
142    return d;
143}
144
145#define IS_IDENTIFIER_CHAR(c) ((c) - '0' <= 9U || (c) - 'a' <= 25U || (c) - 'A' <= 25U || (c) == '_')
146
147static int strmatch(const char *s, const char *prefix)
148{
149    int i;
150    for (i=0; prefix[i]; i++) {
151        if (prefix[i] != s[i]) return 0;
152    }
153    /* return 1 only if the s identifier is terminated */
154    return !IS_IDENTIFIER_CHAR(s[i]);
155}
156
157struct AVExpr {
158    enum {
159        e_value, e_const, e_func0, e_func1, e_func2,
160        e_squish, e_gauss, e_ld, e_isnan, e_isinf,
161        e_mod, e_max, e_min, e_eq, e_gt, e_gte, e_lte, e_lt,
162        e_pow, e_mul, e_div, e_add,
163        e_last, e_st, e_while, e_taylor, e_root, e_floor, e_ceil, e_trunc, e_round,
164        e_sqrt, e_not, e_random, e_hypot, e_gcd,
165        e_if, e_ifnot, e_print, e_bitand, e_bitor, e_between, e_clip, e_atan2, e_lerp,
166        e_sgn,
167    } type;
168    double value; // is sign in other types
169    int const_index;
170    union {
171        double (*func0)(double);
172        double (*func1)(void *, double);
173        double (*func2)(void *, double, double);
174    } a;
175    struct AVExpr *param[3];
176    double *var;
177};
178
179static double etime(double v)
180{
181    return av_gettime() * 0.000001;
182}
183
184static double eval_expr(Parser *p, AVExpr *e)
185{
186    switch (e->type) {
187        case e_value:  return e->value;
188        case e_const:  return e->value * p->const_values[e->const_index];
189        case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));
190        case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));
191        case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));
192        case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));
193        case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }
194        case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];
195        case e_isnan:  return e->value * !!isnan(eval_expr(p, e->param[0]));
196        case e_isinf:  return e->value * !!isinf(eval_expr(p, e->param[0]));
197        case e_floor:  return e->value * floor(eval_expr(p, e->param[0]));
198        case e_ceil :  return e->value * ceil (eval_expr(p, e->param[0]));
199        case e_trunc:  return e->value * trunc(eval_expr(p, e->param[0]));
200        case e_round:  return e->value * round(eval_expr(p, e->param[0]));
201        case e_sgn:    return e->value * FFDIFFSIGN(eval_expr(p, e->param[0]), 0);
202        case e_sqrt:   return e->value * sqrt (eval_expr(p, e->param[0]));
203        case e_not:    return e->value * (eval_expr(p, e->param[0]) == 0);
204        case e_if:     return e->value * (eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) :
205                                          e->param[2] ? eval_expr(p, e->param[2]) : 0);
206        case e_ifnot:  return e->value * (!eval_expr(p, e->param[0]) ? eval_expr(p, e->param[1]) :
207                                          e->param[2] ? eval_expr(p, e->param[2]) : 0);
208        case e_clip: {
209            double x = eval_expr(p, e->param[0]);
210            double min = eval_expr(p, e->param[1]), max = eval_expr(p, e->param[2]);
211            if (isnan(min) || isnan(max) || isnan(x) || min > max)
212                return NAN;
213            return e->value * av_clipd(eval_expr(p, e->param[0]), min, max);
214        }
215        case e_between: {
216            double d = eval_expr(p, e->param[0]);
217            return e->value * (d >= eval_expr(p, e->param[1]) &&
218                               d <= eval_expr(p, e->param[2]));
219        }
220        case e_lerp: {
221            double v0 = eval_expr(p, e->param[0]);
222            double v1 = eval_expr(p, e->param[1]);
223            double f  = eval_expr(p, e->param[2]);
224            return v0 + (v1 - v0) * f;
225        }
226        case e_print: {
227            double x = eval_expr(p, e->param[0]);
228            int level = e->param[1] ? av_clip(eval_expr(p, e->param[1]), INT_MIN, INT_MAX) : AV_LOG_INFO;
229            av_log(p, level, "%f\n", x);
230            return x;
231        }
232        case e_random:{
233            int idx= av_clip(eval_expr(p, e->param[0]), 0, VARS-1);
234            uint64_t r= isnan(p->var[idx]) ? 0 : p->var[idx];
235            r= r*1664525+1013904223;
236            p->var[idx]= r;
237            return e->value * (r * (1.0/UINT64_MAX));
238        }
239        case e_while: {
240            double d = NAN;
241            while (eval_expr(p, e->param[0]))
242                d=eval_expr(p, e->param[1]);
243            return d;
244        }
245        case e_taylor: {
246            double t = 1, d = 0, v;
247            double x = eval_expr(p, e->param[1]);
248            int id = e->param[2] ? av_clip(eval_expr(p, e->param[2]), 0, VARS-1) : 0;
249            int i;
250            double var0 = p->var[id];
251            for(i=0; i<1000; i++) {
252                double ld = d;
253                p->var[id] = i;
254                v = eval_expr(p, e->param[0]);
255                d += t*v;
256                if(ld==d && v)
257                    break;
258                t *= x / (i+1);
259            }
260            p->var[id] = var0;
261            return d;
262        }
263        case e_root: {
264            int i, j;
265            double low = -1, high = -1, v, low_v = -DBL_MAX, high_v = DBL_MAX;
266            double var0 = p->var[0];
267            double x_max = eval_expr(p, e->param[1]);
268            for(i=-1; i<1024; i++) {
269                if(i<255) {
270                    p->var[0] = ff_reverse[i&255]*x_max/255;
271                } else {
272                    p->var[0] = x_max*pow(0.9, i-255);
273                    if (i&1) p->var[0] *= -1;
274                    if (i&2) p->var[0] += low;
275                    else     p->var[0] += high;
276                }
277                v = eval_expr(p, e->param[0]);
278                if (v<=0 && v>low_v) {
279                    low    = p->var[0];
280                    low_v  = v;
281                }
282                if (v>=0 && v<high_v) {
283                    high   = p->var[0];
284                    high_v = v;
285                }
286                if (low>=0 && high>=0){
287                    for (j=0; j<1000; j++) {
288                        p->var[0] = (low+high)*0.5;
289                        if (low == p->var[0] || high == p->var[0])
290                            break;
291                        v = eval_expr(p, e->param[0]);
292                        if (v<=0) low = p->var[0];
293                        if (v>=0) high= p->var[0];
294                        if (isnan(v)) {
295                            low = high = v;
296                            break;
297                        }
298                    }
299                    break;
300                }
301            }
302            p->var[0] = var0;
303            return -low_v<high_v ? low : high;
304        }
305        default: {
306            double d = eval_expr(p, e->param[0]);
307            double d2 = eval_expr(p, e->param[1]);
308            switch (e->type) {
309                case e_mod: return e->value * (d - floor((!CONFIG_FTRAPV || d2) ? d / d2 : d * INFINITY) * d2);
310                case e_gcd: return e->value * av_gcd(d,d2);
311                case e_max: return e->value * (d >  d2 ?   d : d2);
312                case e_min: return e->value * (d <  d2 ?   d : d2);
313                case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);
314                case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);
315                case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);
316                case e_lt:  return e->value * (d <  d2 ? 1.0 : 0.0);
317                case e_lte: return e->value * (d <= d2 ? 1.0 : 0.0);
318                case e_pow: return e->value * pow(d, d2);
319                case e_mul: return e->value * (d * d2);
320                case e_div: return e->value * ((!CONFIG_FTRAPV || d2 ) ? (d / d2) : d * INFINITY);
321                case e_add: return e->value * (d + d2);
322                case e_last:return e->value * d2;
323                case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);
324                case e_hypot:return e->value * hypot(d, d2);
325                case e_atan2:return e->value * atan2(d, d2);
326                case e_bitand: return isnan(d) || isnan(d2) ? NAN : e->value * ((long int)d & (long int)d2);
327                case e_bitor:  return isnan(d) || isnan(d2) ? NAN : e->value * ((long int)d | (long int)d2);
328            }
329        }
330    }
331    return NAN;
332}
333
334static int parse_expr(AVExpr **e, Parser *p);
335
336void av_expr_free(AVExpr *e)
337{
338    if (!e) return;
339    av_expr_free(e->param[0]);
340    av_expr_free(e->param[1]);
341    av_expr_free(e->param[2]);
342    av_freep(&e->var);
343    av_freep(&e);
344}
345
346static int parse_primary(AVExpr **e, Parser *p)
347{
348    AVExpr *d = av_mallocz(sizeof(AVExpr));
349    char *next = p->s, *s0 = p->s;
350    int ret, i;
351
352    if (!d)
353        return AVERROR(ENOMEM);
354
355    /* number */
356    d->value = av_strtod(p->s, &next);
357    if (next != p->s) {
358        d->type = e_value;
359        p->s= next;
360        *e = d;
361        return 0;
362    }
363    d->value = 1;
364
365    /* named constants */
366    for (i=0; p->const_names && p->const_names[i]; i++) {
367        if (strmatch(p->s, p->const_names[i])) {
368            p->s+= strlen(p->const_names[i]);
369            d->type = e_const;
370            d->const_index = i;
371            *e = d;
372            return 0;
373        }
374    }
375    for (i = 0; i < FF_ARRAY_ELEMS(constants); i++) {
376        if (strmatch(p->s, constants[i].name)) {
377            p->s += strlen(constants[i].name);
378            d->type = e_value;
379            d->value = constants[i].value;
380            *e = d;
381            return 0;
382        }
383    }
384
385    p->s= strchr(p->s, '(');
386    if (!p->s) {
387        av_log(p, AV_LOG_ERROR, "Undefined constant or missing '(' in '%s'\n", s0);
388        p->s= next;
389        av_expr_free(d);
390        return AVERROR(EINVAL);
391    }
392    p->s++; // "("
393    if (*next == '(') { // special case do-nothing
394        av_freep(&d);
395        if ((ret = parse_expr(&d, p)) < 0)
396            return ret;
397        if (p->s[0] != ')') {
398            av_log(p, AV_LOG_ERROR, "Missing ')' in '%s'\n", s0);
399            av_expr_free(d);
400            return AVERROR(EINVAL);
401        }
402        p->s++; // ")"
403        *e = d;
404        return 0;
405    }
406    if ((ret = parse_expr(&(d->param[0]), p)) < 0) {
407        av_expr_free(d);
408        return ret;
409    }
410    if (p->s[0]== ',') {
411        p->s++; // ","
412        parse_expr(&d->param[1], p);
413    }
414    if (p->s[0]== ',') {
415        p->s++; // ","
416        parse_expr(&d->param[2], p);
417    }
418    if (p->s[0] != ')') {
419        av_log(p, AV_LOG_ERROR, "Missing ')' or too many args in '%s'\n", s0);
420        av_expr_free(d);
421        return AVERROR(EINVAL);
422    }
423    p->s++; // ")"
424
425    d->type = e_func0;
426         if (strmatch(next, "sinh"  )) d->a.func0 = sinh;
427    else if (strmatch(next, "cosh"  )) d->a.func0 = cosh;
428    else if (strmatch(next, "tanh"  )) d->a.func0 = tanh;
429    else if (strmatch(next, "sin"   )) d->a.func0 = sin;
430    else if (strmatch(next, "cos"   )) d->a.func0 = cos;
431    else if (strmatch(next, "tan"   )) d->a.func0 = tan;
432    else if (strmatch(next, "atan"  )) d->a.func0 = atan;
433    else if (strmatch(next, "asin"  )) d->a.func0 = asin;
434    else if (strmatch(next, "acos"  )) d->a.func0 = acos;
435    else if (strmatch(next, "exp"   )) d->a.func0 = exp;
436    else if (strmatch(next, "log"   )) d->a.func0 = log;
437    else if (strmatch(next, "abs"   )) d->a.func0 = fabs;
438    else if (strmatch(next, "time"  )) d->a.func0 = etime;
439    else if (strmatch(next, "squish")) d->type = e_squish;
440    else if (strmatch(next, "gauss" )) d->type = e_gauss;
441    else if (strmatch(next, "mod"   )) d->type = e_mod;
442    else if (strmatch(next, "max"   )) d->type = e_max;
443    else if (strmatch(next, "min"   )) d->type = e_min;
444    else if (strmatch(next, "eq"    )) d->type = e_eq;
445    else if (strmatch(next, "gte"   )) d->type = e_gte;
446    else if (strmatch(next, "gt"    )) d->type = e_gt;
447    else if (strmatch(next, "lte"   )) d->type = e_lte;
448    else if (strmatch(next, "lt"    )) d->type = e_lt;
449    else if (strmatch(next, "ld"    )) d->type = e_ld;
450    else if (strmatch(next, "isnan" )) d->type = e_isnan;
451    else if (strmatch(next, "isinf" )) d->type = e_isinf;
452    else if (strmatch(next, "st"    )) d->type = e_st;
453    else if (strmatch(next, "while" )) d->type = e_while;
454    else if (strmatch(next, "taylor")) d->type = e_taylor;
455    else if (strmatch(next, "root"  )) d->type = e_root;
456    else if (strmatch(next, "floor" )) d->type = e_floor;
457    else if (strmatch(next, "ceil"  )) d->type = e_ceil;
458    else if (strmatch(next, "trunc" )) d->type = e_trunc;
459    else if (strmatch(next, "round" )) d->type = e_round;
460    else if (strmatch(next, "sqrt"  )) d->type = e_sqrt;
461    else if (strmatch(next, "not"   )) d->type = e_not;
462    else if (strmatch(next, "pow"   )) d->type = e_pow;
463    else if (strmatch(next, "print" )) d->type = e_print;
464    else if (strmatch(next, "random")) d->type = e_random;
465    else if (strmatch(next, "hypot" )) d->type = e_hypot;
466    else if (strmatch(next, "gcd"   )) d->type = e_gcd;
467    else if (strmatch(next, "if"    )) d->type = e_if;
468    else if (strmatch(next, "ifnot" )) d->type = e_ifnot;
469    else if (strmatch(next, "bitand")) d->type = e_bitand;
470    else if (strmatch(next, "bitor" )) d->type = e_bitor;
471    else if (strmatch(next, "between"))d->type = e_between;
472    else if (strmatch(next, "clip"  )) d->type = e_clip;
473    else if (strmatch(next, "atan2" )) d->type = e_atan2;
474    else if (strmatch(next, "lerp"  )) d->type = e_lerp;
475    else if (strmatch(next, "sgn"   )) d->type = e_sgn;
476    else {
477        for (i=0; p->func1_names && p->func1_names[i]; i++) {
478            if (strmatch(next, p->func1_names[i])) {
479                d->a.func1 = p->funcs1[i];
480                d->type = e_func1;
481                d->const_index = i;
482                *e = d;
483                return 0;
484            }
485        }
486
487        for (i=0; p->func2_names && p->func2_names[i]; i++) {
488            if (strmatch(next, p->func2_names[i])) {
489                d->a.func2 = p->funcs2[i];
490                d->type = e_func2;
491                d->const_index = i;
492                *e = d;
493                return 0;
494            }
495        }
496
497        av_log(p, AV_LOG_ERROR, "Unknown function in '%s'\n", s0);
498        av_expr_free(d);
499        return AVERROR(EINVAL);
500    }
501
502    *e = d;
503    return 0;
504}
505
506static AVExpr *make_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1)
507{
508    AVExpr *e = av_mallocz(sizeof(AVExpr));
509    if (!e)
510        return NULL;
511    e->type     =type   ;
512    e->value    =value  ;
513    e->param[0] =p0     ;
514    e->param[1] =p1     ;
515    return e;
516}
517
518static int parse_pow(AVExpr **e, Parser *p, int *sign)
519{
520    *sign= (*p->s == '+') - (*p->s == '-');
521    p->s += *sign&1;
522    return parse_primary(e, p);
523}
524
525static int parse_dB(AVExpr **e, Parser *p, int *sign)
526{
527    /* do not filter out the negative sign when parsing a dB value.
528       for example, -3dB is not the same as -(3dB) */
529    if (*p->s == '-') {
530        char *next;
531        double av_unused ignored = strtod(p->s, &next);
532        if (next != p->s && next[0] == 'd' && next[1] == 'B') {
533            *sign = 0;
534            return parse_primary(e, p);
535        }
536    }
537    return parse_pow(e, p, sign);
538}
539
540static int parse_factor(AVExpr **e, Parser *p)
541{
542    int sign, sign2, ret;
543    AVExpr *e0, *e1, *e2;
544    if ((ret = parse_dB(&e0, p, &sign)) < 0)
545        return ret;
546    while(p->s[0]=='^'){
547        e1 = e0;
548        p->s++;
549        if ((ret = parse_dB(&e2, p, &sign2)) < 0) {
550            av_expr_free(e1);
551            return ret;
552        }
553        e0 = make_eval_expr(e_pow, 1, e1, e2);
554        if (!e0) {
555            av_expr_free(e1);
556            av_expr_free(e2);
557            return AVERROR(ENOMEM);
558        }
559        if (e0->param[1]) e0->param[1]->value *= (sign2|1);
560    }
561    if (e0) e0->value *= (sign|1);
562
563    *e = e0;
564    return 0;
565}
566
567static int parse_term(AVExpr **e, Parser *p)
568{
569    int ret;
570    AVExpr *e0, *e1, *e2;
571    if ((ret = parse_factor(&e0, p)) < 0)
572        return ret;
573    while (p->s[0]=='*' || p->s[0]=='/') {
574        int c= *p->s++;
575        e1 = e0;
576        if ((ret = parse_factor(&e2, p)) < 0) {
577            av_expr_free(e1);
578            return ret;
579        }
580        e0 = make_eval_expr(c == '*' ? e_mul : e_div, 1, e1, e2);
581        if (!e0) {
582            av_expr_free(e1);
583            av_expr_free(e2);
584            return AVERROR(ENOMEM);
585        }
586    }
587    *e = e0;
588    return 0;
589}
590
591static int parse_subexpr(AVExpr **e, Parser *p)
592{
593    int ret;
594    AVExpr *e0, *e1, *e2;
595    if ((ret = parse_term(&e0, p)) < 0)
596        return ret;
597    while (*p->s == '+' || *p->s == '-') {
598        e1 = e0;
599        if ((ret = parse_term(&e2, p)) < 0) {
600            av_expr_free(e1);
601            return ret;
602        }
603        e0 = make_eval_expr(e_add, 1, e1, e2);
604        if (!e0) {
605            av_expr_free(e1);
606            av_expr_free(e2);
607            return AVERROR(ENOMEM);
608        }
609    };
610
611    *e = e0;
612    return 0;
613}
614
615static int parse_expr(AVExpr **e, Parser *p)
616{
617    int ret;
618    AVExpr *e0, *e1, *e2;
619    if (p->stack_index <= 0) //protect against stack overflows
620        return AVERROR(EINVAL);
621    p->stack_index--;
622
623    if ((ret = parse_subexpr(&e0, p)) < 0)
624        return ret;
625    while (*p->s == ';') {
626        p->s++;
627        e1 = e0;
628        if ((ret = parse_subexpr(&e2, p)) < 0) {
629            av_expr_free(e1);
630            return ret;
631        }
632        e0 = make_eval_expr(e_last, 1, e1, e2);
633        if (!e0) {
634            av_expr_free(e1);
635            av_expr_free(e2);
636            return AVERROR(ENOMEM);
637        }
638    };
639
640    p->stack_index++;
641    *e = e0;
642    return 0;
643}
644
645static int verify_expr(AVExpr *e)
646{
647    if (!e) return 0;
648    switch (e->type) {
649        case e_value:
650        case e_const: return 1;
651        case e_func0:
652        case e_func1:
653        case e_squish:
654        case e_ld:
655        case e_gauss:
656        case e_isnan:
657        case e_isinf:
658        case e_floor:
659        case e_ceil:
660        case e_trunc:
661        case e_round:
662        case e_sqrt:
663        case e_not:
664        case e_random:
665        case e_sgn:
666            return verify_expr(e->param[0]) && !e->param[1];
667        case e_print:
668            return verify_expr(e->param[0])
669                   && (!e->param[1] || verify_expr(e->param[1]));
670        case e_if:
671        case e_ifnot:
672        case e_taylor:
673            return verify_expr(e->param[0]) && verify_expr(e->param[1])
674                   && (!e->param[2] || verify_expr(e->param[2]));
675        case e_between:
676        case e_clip:
677        case e_lerp:
678            return verify_expr(e->param[0]) &&
679                   verify_expr(e->param[1]) &&
680                   verify_expr(e->param[2]);
681        default: return verify_expr(e->param[0]) && verify_expr(e->param[1]) && !e->param[2];
682    }
683}
684
685int av_expr_parse(AVExpr **expr, const char *s,
686                  const char * const *const_names,
687                  const char * const *func1_names, double (* const *funcs1)(void *, double),
688                  const char * const *func2_names, double (* const *funcs2)(void *, double, double),
689                  int log_offset, void *log_ctx)
690{
691    Parser p = { 0 };
692    AVExpr *e = NULL;
693    char *w = av_malloc(strlen(s) + 1);
694    char *wp = w;
695    const char *s0 = s;
696    int ret = 0;
697
698    if (!w)
699        return AVERROR(ENOMEM);
700
701    while (*s)
702        if (!av_isspace(*s++)) *wp++ = s[-1];
703    *wp++ = 0;
704
705    p.class      = &eval_class;
706    p.stack_index=100;
707    p.s= w;
708    p.const_names = const_names;
709    p.funcs1      = funcs1;
710    p.func1_names = func1_names;
711    p.funcs2      = funcs2;
712    p.func2_names = func2_names;
713    p.log_offset = log_offset;
714    p.log_ctx    = log_ctx;
715
716    if ((ret = parse_expr(&e, &p)) < 0)
717        goto end;
718    if (*p.s) {
719        av_log(&p, AV_LOG_ERROR, "Invalid chars '%s' at the end of expression '%s'\n", p.s, s0);
720        ret = AVERROR(EINVAL);
721        goto end;
722    }
723    if (!verify_expr(e)) {
724        ret = AVERROR(EINVAL);
725        goto end;
726    }
727    e->var= av_mallocz(sizeof(double) *VARS);
728    if (!e->var) {
729        ret = AVERROR(ENOMEM);
730        goto end;
731    }
732    *expr = e;
733    e = NULL;
734end:
735    av_expr_free(e);
736    av_free(w);
737    return ret;
738}
739
740static int expr_count(AVExpr *e, unsigned *counter, int size, int type)
741{
742    int i;
743
744    if (!e || !counter || !size)
745        return AVERROR(EINVAL);
746
747    for (i = 0; e->type != type && i < 3 && e->param[i]; i++)
748        expr_count(e->param[i], counter, size, type);
749
750    if (e->type == type && e->const_index < size)
751        counter[e->const_index]++;
752
753    return 0;
754}
755
756int av_expr_count_vars(AVExpr *e, unsigned *counter, int size)
757{
758    return expr_count(e, counter, size, e_const);
759}
760
761int av_expr_count_func(AVExpr *e, unsigned *counter, int size, int arg)
762{
763    return expr_count(e, counter, size, ((int[]){e_const, e_func1, e_func2})[arg]);
764}
765
766double av_expr_eval(AVExpr *e, const double *const_values, void *opaque)
767{
768    Parser p = { 0 };
769    p.var= e->var;
770
771    p.const_values = const_values;
772    p.opaque     = opaque;
773    return eval_expr(&p, e);
774}
775
776int av_expr_parse_and_eval(double *d, const char *s,
777                           const char * const *const_names, const double *const_values,
778                           const char * const *func1_names, double (* const *funcs1)(void *, double),
779                           const char * const *func2_names, double (* const *funcs2)(void *, double, double),
780                           void *opaque, int log_offset, void *log_ctx)
781{
782    AVExpr *e = NULL;
783    int ret = av_expr_parse(&e, s, const_names, func1_names, funcs1, func2_names, funcs2, log_offset, log_ctx);
784
785    if (ret < 0) {
786        *d = NAN;
787        return ret;
788    }
789    *d = av_expr_eval(e, const_values, opaque);
790    av_expr_free(e);
791    return isnan(*d) ? AVERROR(EINVAL) : 0;
792}