/* * Copyright (c) 2002-2006 Michael Niedermayer <michaelni@gmx.at> * Copyright (c) 2006 Oded Shimon <ods15@ods15.dyndns.org> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * simple arithmetic expression evaluator. * * see http://joe.hotchkiss.com/programming/eval/eval.html */ #include "libavutil/avutil.h"#include "eval.h" typedef struct Parser{    const AVClass *class;    int stack_index;    char *s;    const double *const_value;    const char * const *const_name;          // NULL terminated    double (* const *func1)(void *, double a);           // NULL terminated    const char * const *func1_name;          // NULL terminated    double (* const *func2)(void *, double a, double b); // NULL terminated    const char * const *func2_name;          // NULL terminated    void *opaque;    int log_offset;    void *log_ctx;#define VARS 10    double var[VARS];} Parser; static const AVClass class = { "Eval", av_default_item_name, NULL, LIBAVUTIL_VERSION_INT, offsetof(Parser,log_offset), offsetof(Parser,log_ctx) }; static const int8_t si_prefixes['z' - 'E' + 1]={    ['y'-'E']= -24,    ['z'-'E']= -21,    ['a'-'E']= -18,    ['f'-'E']= -15,    ['p'-'E']= -12,    ['n'-'E']= - 9,    ['u'-'E']= - 6,    ['m'-'E']= - 3,    ['c'-'E']= - 2,    ['d'-'E']= - 1,    ['h'-'E']=   2,    ['k'-'E']=   3,    ['K'-'E']=   3,    ['M'-'E']=   6,    ['G'-'E']=   9,    ['T'-'E']=  12,    ['P'-'E']=  15,    ['E'-'E']=  18,    ['Z'-'E']=  21,    ['Y'-'E']=  24,}; double av_strtod(const char *numstr, char **tail) {    double d;    char *next;    d = strtod(numstr, &next);    /* if parsing succeeded, check for and interpret postfixes */    if (next!=numstr) {         if(*next >= 'E' && *next <= 'z'){            int e= si_prefixes[*next - 'E'];            if(e){                if(next[1] == 'i'){                    d*= pow( 2, e/0.3);                    next+=2;                }else{                    d*= pow(10, e);                    next++;                }            }        }         if(*next=='B') {            d*=8;            next++;        }    }    /* if requested, fill in tail with the position after the last parsed       character */    if (tail)        *tail = next;    return d;} static int strmatch(const char *s, const char *prefix){    int i;    for(i=0; prefix[i]; i++){        if(prefix[i] != s[i]) return 0;    }    return 1;} struct AVExpr {    enum {        e_value, e_const, e_func0, e_func1, e_func2,        e_squish, e_gauss, e_ld,        e_mod, e_max, e_min, e_eq, e_gt, e_gte,        e_pow, e_mul, e_div, e_add,        e_last, e_st, e_while,    } type;    double value; // is sign in other types    union {        int const_index;        double (*func0)(double);        double (*func1)(void *, double);        double (*func2)(void *, double, double);    } a;    struct AVExpr *param[2];}; static double eval_expr(Parser * p, AVExpr * e) {    switch (e->type) {        case e_value:  return e->value;        case e_const:  return e->value * p->const_value[e->a.const_index];        case e_func0:  return e->value * e->a.func0(eval_expr(p, e->param[0]));        case e_func1:  return e->value * e->a.func1(p->opaque, eval_expr(p, e->param[0]));        case e_func2:  return e->value * e->a.func2(p->opaque, eval_expr(p, e->param[0]), eval_expr(p, e->param[1]));        case e_squish: return 1/(1+exp(4*eval_expr(p, e->param[0])));        case e_gauss: { double d = eval_expr(p, e->param[0]); return exp(-d*d/2)/sqrt(2*M_PI); }        case e_ld:     return e->value * p->var[av_clip(eval_expr(p, e->param[0]), 0, VARS-1)];        case e_while: {            double d = NAN;            while(eval_expr(p, e->param[0]))                d=eval_expr(p, e->param[1]);            return d;        }        default: {            double d = eval_expr(p, e->param[0]);            double d2 = eval_expr(p, e->param[1]);            switch (e->type) {                case e_mod: return e->value * (d - floor(d/d2)*d2);                case e_max: return e->value * (d >  d2 ?   d : d2);                case e_min: return e->value * (d <  d2 ?   d : d2);                case e_eq:  return e->value * (d == d2 ? 1.0 : 0.0);                case e_gt:  return e->value * (d >  d2 ? 1.0 : 0.0);                case e_gte: return e->value * (d >= d2 ? 1.0 : 0.0);                case e_pow: return e->value * pow(d, d2);                case e_mul: return e->value * (d * d2);                case e_div: return e->value * (d / d2);                case e_add: return e->value * (d + d2);                case e_last:return e->value * d2;                case e_st : return e->value * (p->var[av_clip(d, 0, VARS-1)]= d2);            }        }    }    return NAN;} static AVExpr * parse_expr(Parser *p); void ff_free_expr(AVExpr * e) {    if (!e) return;    ff_free_expr(e->param[0]);    ff_free_expr(e->param[1]);    av_freep(&e);} static AVExpr * parse_primary(Parser *p) {    AVExpr * d = av_mallocz(sizeof(AVExpr));    char *next= p->s;    int i;     if (!d)        return NULL;     /* number */    d->value = av_strtod(p->s, &next);    if(next != p->s){        d->type = e_value;        p->s= next;        return d;    }    d->value = 1;     /* named constants */    for(i=0; p->const_name && p->const_name[i]; i++){        if(strmatch(p->s, p->const_name[i])){            p->s+= strlen(p->const_name[i]);            d->type = e_const;            d->a.const_index = i;            return d;        }    }     p->s= strchr(p->s, '(');    if(p->s==NULL){        av_log(p, AV_LOG_ERROR, "undefined constant or missing (\n");        p->s= next;        ff_free_expr(d);        return NULL;    }    p->s++; // "("    if (*next == '(') { // special case do-nothing        av_freep(&d);        d = parse_expr(p);        if(p->s[0] != ')'){            av_log(p, AV_LOG_ERROR, "missing )\n");            ff_free_expr(d);            return NULL;        }        p->s++; // ")"        return d;    }    d->param[0] = parse_expr(p);    if(p->s[0]== ','){        p->s++; // ","        d->param[1] = parse_expr(p);    }    if(p->s[0] != ')'){        av_log(p, AV_LOG_ERROR, "missing )\n");        ff_free_expr(d);        return NULL;    }    p->s++; // ")"     d->type = e_func0;         if( strmatch(next, "sinh"  ) ) d->a.func0 = sinh;    else if( strmatch(next, "cosh"  ) ) d->a.func0 = cosh;    else if( strmatch(next, "tanh"  ) ) d->a.func0 = tanh;    else if( strmatch(next, "sin"   ) ) d->a.func0 = sin;    else if( strmatch(next, "cos"   ) ) d->a.func0 = cos;    else if( strmatch(next, "tan"   ) ) d->a.func0 = tan;    else if( strmatch(next, "atan"  ) ) d->a.func0 = atan;    else if( strmatch(next, "asin"  ) ) d->a.func0 = asin;    else if( strmatch(next, "acos"  ) ) d->a.func0 = acos;    else if( strmatch(next, "exp"   ) ) d->a.func0 = exp;    else if( strmatch(next, "log"   ) ) d->a.func0 = log;    else if( strmatch(next, "abs"   ) ) d->a.func0 = fabs;    else if( strmatch(next, "squish") ) d->type = e_squish;    else if( strmatch(next, "gauss" ) ) d->type = e_gauss;    else if( strmatch(next, "mod"   ) ) d->type = e_mod;    else if( strmatch(next, "max"   ) ) d->type = e_max;    else if( strmatch(next, "min"   ) ) d->type = e_min;    else if( strmatch(next, "eq"    ) ) d->type = e_eq;    else if( strmatch(next, "gte"   ) ) d->type = e_gte;    else if( strmatch(next, "gt"    ) ) d->type = e_gt;    else if( strmatch(next, "lte"   ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gt; }    else if( strmatch(next, "lt"    ) ) { AVExpr * tmp = d->param[1]; d->param[1] = d->param[0]; d->param[0] = tmp; d->type = e_gte; }    else if( strmatch(next, "ld"    ) ) d->type = e_ld;    else if( strmatch(next, "st"    ) ) d->type = e_st;    else if( strmatch(next, "while" ) ) d->type = e_while;    else {        for(i=0; p->func1_name && p->func1_name[i]; i++){            if(strmatch(next, p->func1_name[i])){                d->a.func1 = p->func1[i];                d->type = e_func1;                return d;            }        }         for(i=0; p->func2_name && p->func2_name[i]; i++){            if(strmatch(next, p->func2_name[i])){                d->a.func2 = p->func2[i];                d->type = e_func2;                return d;            }        }         av_log(p, AV_LOG_ERROR, "unknown function\n");        ff_free_expr(d);        return NULL;    }     return d;} static AVExpr * new_eval_expr(int type, int value, AVExpr *p0, AVExpr *p1){    AVExpr * e = av_mallocz(sizeof(AVExpr));    if (!e)        return NULL;    e->type     =type   ;    e->value    =value  ;    e->param[0] =p0     ;    e->param[1] =p1     ;    return e;} static AVExpr * parse_pow(Parser *p, int *sign){    *sign= (*p->s == '+') - (*p->s == '-');    p->s += *sign&1;    return parse_primary(p);} static AVExpr * parse_factor(Parser *p){    int sign, sign2;    AVExpr * e = parse_pow(p, &sign);    while(p->s[0]=='^'){        p->s++;        e= new_eval_expr(e_pow, 1, e, parse_pow(p, &sign2));        if (!e)            return NULL;        if (e->param[1]) e->param[1]->value *= (sign2|1);    }    if (e) e->value *= (sign|1);    return e;} static AVExpr * parse_term(Parser *p){    AVExpr * e = parse_factor(p);    while(p->s[0]=='*' || p->s[0]=='/'){        int c= *p->s++;        e= new_eval_expr(c == '*' ? e_mul : e_div, 1, e, parse_factor(p));        if (!e)            return NULL;    }    return e;} static AVExpr * parse_subexpr(Parser *p) {    AVExpr * e = parse_term(p);    while(*p->s == '+' || *p->s == '-') {        e= new_eval_expr(e_add, 1, e, parse_term(p));        if (!e)            return NULL;    };     return e;} static AVExpr * parse_expr(Parser *p) {    AVExpr * e;     if(p->stack_index <= 0) //protect against stack overflows        return NULL;    p->stack_index--;     e = parse_subexpr(p);     while(*p->s == ';') {        p->s++;        e= new_eval_expr(e_last, 1, e, parse_subexpr(p));        if (!e)            return NULL;    };     p->stack_index++;     return e;} static int verify_expr(AVExpr * e) {    if (!e) return 0;    switch (e->type) {        case e_value:        case e_const: return 1;        case e_func0:        case e_func1:        case e_squish:        case e_ld:        case e_gauss: return verify_expr(e->param[0]);        default: return verify_expr(e->param[0]) && verify_expr(e->param[1]);    }} AVExpr *ff_parse_expr(const char *s,                      const char * const *const_name,                      const char * const *func1_name, double (* const *func1)(void *, double),                      const char * const *func2_name, double (* const *func2)(void *, double, double),                      int log_offset, void *log_ctx){    Parser p;    AVExpr *e = NULL;    char *w = av_malloc(strlen(s) + 1);    char *wp = w;     if (!w)        goto end;     while (*s)        if (!isspace(*s++)) *wp++ = s[-1];    *wp++ = 0;     p.class      = &class;    p.stack_index=100;    p.s= w;    p.const_name = const_name;    p.func1      = func1;    p.func1_name = func1_name;    p.func2      = func2;    p.func2_name = func2_name;    p.log_offset = log_offset;    p.log_ctx    = log_ctx;     e = parse_expr(&p);    if (!verify_expr(e)) {        ff_free_expr(e);        e = NULL;    }end:    av_free(w);    return e;} double ff_eval_expr(AVExpr * e, const double *const_value, void *opaque) {    Parser p;     p.const_value= const_value;    p.opaque     = opaque;    return eval_expr(&p, e);} double ff_parse_and_eval_expr(const char *s,                              const char * const *const_name, const double *const_value,                              const char * const *func1_name, double (* const *func1)(void *, double),                              const char * const *func2_name, double (* const *func2)(void *, double, double),                              void *opaque, int log_offset, void *log_ctx){    AVExpr *e = ff_parse_expr(s, const_name, func1_name, func1, func2_name, func2, log_offset, log_ctx);    double d;    if (!e) return NAN;    d = ff_eval_expr(e, const_value, opaque);    ff_free_expr(e);    return d;} #ifdef TEST#undef printfstatic double const_values[]={    M_PI,    M_E,    0};static const char *const_names[]={    "PI",    "E",    0};int main(void){    int i;    printf("%f == 12.7\n", ff_parse_and_eval_expr("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_names, const_values, NULL, NULL, NULL, NULL, NULL, 0, NULL));    printf("%f == 0.931322575\n", ff_parse_and_eval_expr("80G/80Gi", const_names, const_values, NULL, NULL, NULL, NULL, NULL, NULL));     for(i=0; i<1050; i++){        START_TIMER            ff_parse_and_eval_expr("1+(5-2)^(3-1)+1/2+sin(PI)-max(-2.2,-3.1)", const_names, const_values, NULL, NULL, NULL, NULL, NULL, 0, NULL);        STOP_TIMER("ff_parse_and_eval_expr")    }    return 0;}#endif