/* * simple arithmetic expression evaluator * * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at> * * This library 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 of the License, or (at your option) any later version. * * This library 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 this library; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA * *//** * @file eval.c * simple arithmetic expression evaluator. * * see http://joe.hotchkiss.com/programming/eval/eval.html */#include <stdio.h>#include <stdlib.h>#include <string.h>#include <math.h>#ifndef NAN  #define NAN 0#endif#ifndef M_PI#define M_PI 3.14159265358979323846#endif#define STACK_SIZE 100typedef struct Parser{    double stack[STACK_SIZE];    int stack_index;    char *s;    double *const_value;    const char **const_name;          // NULL terminated    double (**func1)(void *, double a); // NULL terminated    const char **func1_name;          // NULL terminated    double (**func2)(void *, double a, double b); // NULL terminated    char **func2_name;          // NULL terminated    void *opaque;} Parser;static void evalExpression(Parser *p);static void push(Parser *p, double d){    if(p->stack_index+1>= STACK_SIZE){        fprintf(stderr, "stack overflow in the parser\n");        return;    }    p->stack[ p->stack_index++ ]= d;//printf("push %f\n", d); fflush(stdout);}static double pop(Parser *p){    if(p->stack_index<=0){        fprintf(stderr, "stack underflow in the parser\n");        return NAN;    }//printf("pop\n"); fflush(stdout);    return p->stack[ --p->stack_index ];}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;}static void evalPrimary(Parser *p){    double d, d2=NAN;    char *next= p->s;    int i;    /* number */    d= strtod(p->s, &next);    if(next != p->s){        push(p, d);        p->s= next;        return;    }    /* named constants */    for(i=0; p->const_name[i]; i++){        if(strmatch(p->s, p->const_name[i])){            push(p, p->const_value[i]);            p->s+= strlen(p->const_name[i]);            return;        }    }    p->s= strchr(p->s, '(');    if(p->s==NULL){        fprintf(stderr, "Parser: missing ( in \"%s\"\n", next);        return;    }    p->s++; // "("    evalExpression(p);    d= pop(p);    if(p->s[0]== ','){        p->s++; // ","        evalExpression(p);        d2= pop(p);    }    if(p->s[0] != ')'){        fprintf(stderr, "Parser: missing ) in \"%s\"\n", next);        return;    }    p->s++; // ")"         if( strmatch(next, "sinh"  ) ) d= sinh(d);    else if( strmatch(next, "cosh"  ) ) d= cosh(d);    else if( strmatch(next, "tanh"  ) ) d= tanh(d);    else if( strmatch(next, "sin"   ) ) d= sin(d);    else if( strmatch(next, "cos"   ) ) d= cos(d);    else if( strmatch(next, "tan"   ) ) d= tan(d);    else if( strmatch(next, "exp"   ) ) d= exp(d);    else if( strmatch(next, "log"   ) ) d= log(d);    else if( strmatch(next, "squish") ) d= 1/(1+exp(4*d));    else if( strmatch(next, "gauss" ) ) d= exp(-d*d/2)/sqrt(2*M_PI);    else if( strmatch(next, "abs"   ) ) d= fabs(d);    else if( strmatch(next, "max"   ) ) d= d > d2 ? d : d2;    else if( strmatch(next, "min"   ) ) d= d < d2 ? d : d2;    else if( strmatch(next, "gt"    ) ) d= d > d2 ? 1.0 : 0.0;    else if( strmatch(next, "gte"    ) ) d= d >= d2 ? 1.0 : 0.0;    else if( strmatch(next, "lt"    ) ) d= d > d2 ? 0.0 : 1.0;    else if( strmatch(next, "lte"    ) ) d= d >= d2 ? 0.0 : 1.0;    else if( strmatch(next, "eq"    ) ) d= d == d2 ? 1.0 : 0.0;//    else if( strmatch(next, "l1"    ) ) d= 1 + d2*(d - 1);//    else if( strmatch(next, "sq01"  ) ) d= (d >= 0.0 && d <=1.0) ? 1.0 : 0.0;    else{        int error=1;        for(i=0; p->func1_name && p->func1_name[i]; i++){            if(strmatch(next, p->func1_name[i])){                d= p->func1[i](p->opaque, d);                error=0;                break;            }        }        for(i=0; p->func2_name && p->func2_name[i]; i++){            if(strmatch(next, p->func2_name[i])){                d= p->func2[i](p->opaque, d, d2);                error=0;                break;            }        }        if(error){            fprintf(stderr, "Parser: unknown function in \"%s\"\n", next);            return;        }    }    push(p, d);}static void evalPow(Parser *p){    int neg= 0;    if(p->s[0]=='+') p->s++;    if(p->s[0]=='-'){        neg= 1;        p->s++;    }    if(p->s[0]=='('){        p->s++;;        evalExpression(p);        if(p->s[0]!=')')            fprintf(stderr, "Parser: missing )\n");        p->s++;    }else{        evalPrimary(p);    }    if(neg) push(p, -pop(p));}static void evalFactor(Parser *p){    evalPow(p);    while(p->s[0]=='^'){        double d;        p->s++;        evalPow(p);        d= pop(p);        push(p, pow(pop(p), d));    }}static void evalTerm(Parser *p){    evalFactor(p);    while(p->s[0]=='*' || p->s[0]=='/'){        int inv= p->s[0]=='/';        double d;        p->s++;        evalFactor(p);        d= pop(p);        if(inv) d= 1.0/d;        push(p, d * pop(p));    }}static void evalExpression(Parser *p){    evalTerm(p);    while(p->s[0]=='+' || p->s[0]=='-'){        int sign= p->s[0]=='-';        double d;        p->s++;        evalTerm(p);        d= pop(p);        if(sign) d= -d;        push(p, d + pop(p));    }}double x264_eval(char *s, double *const_value, const char **const_name,                 double (**func1)(void *, double), const char **func1_name,                 double (**func2)(void *, double, double), char **func2_name,                 void *opaque){    Parser p;    p.stack_index=0;    p.s= s;    p.const_value= const_value;    p.const_name = const_name;    p.func1      = func1;    p.func1_name = func1_name;    p.func2      = func2;    p.func2_name = func2_name;    p.opaque     = opaque;    evalExpression(&p);    return pop(&p);}