ExprtkWrapper.cpp

/**
 * DESCRIPTION OF THE FILE
 *
 * @author Michal Kravčenko
 * @date 4.9.18 -
 */

#include "ExprtkWrapper.h"
#include "exprtk.hpp"


typedef exprtk::symbol_table<double> symbol_table_t;
typedef exprtk::expression<double>     expression_t;
typedef exprtk::parser<double>             parser_t;

class ExprtkWrapper :: ExprtkWrapperImpl {

public:

    /**
     *
     */
    expression_t *expression = nullptr;

    /**
     *
     */
    symbol_table_t *symbol_table = nullptr;

    /**
     *
     */
    parser_t * parser = nullptr;

    /**
     * variables
     */
    double x, y, z, t, f;

    /**
     * referential expression string
     */
    std::string expression_str;
};

ExprtkWrapper::ExprtkWrapper( std::string expression_string ) {

    this->p_impl->expression_str = expression_string;

    this->p_impl->symbol_table = new symbol_table_t( );

    this->p_impl->symbol_table->add_variable("x", this->p_impl->x);
    this->p_impl->symbol_table->add_variable("y", this->p_impl->y);
    this->p_impl->symbol_table->add_variable("z", this->p_impl->z);
    this->p_impl->symbol_table->add_variable("t", this->p_impl->t);
    this->p_impl->symbol_table->add_variable("f", this->p_impl->z);

    this->p_impl->expression = new expression_t( );
    this->p_impl->expression->register_symbol_table( *this->p_impl->symbol_table );

    this->p_impl->parser = new parser_t( );
    this->p_impl->parser->compile(this->p_impl->expression_str, *this->p_impl->expression );
}


ExprtkWrapper::~ExprtkWrapper() {

    if( this->p_impl->expression ){
        delete this->p_impl->expression;
        this->p_impl->expression = nullptr;
    }

    if( this->p_impl->symbol_table ){
        delete this->p_impl->symbol_table;
        this->p_impl->symbol_table = nullptr;
    }

    if( this->p_impl->parser ){
        delete this->p_impl->parser;
        this->p_impl->parser = nullptr;
    }

}

double ExprtkWrapper::eval(double x1, double x2, double x3, double x4) {

    this->p_impl->x = x1;
    this->p_impl->y = x2;
    this->p_impl->z = x3;
    this->p_impl->t = x4;

    return this->p_impl->expression->value();
}

double ExprtkWrapper::eval(std::vector<double> &p) {


    if(p.size() > 0){
        this->p_impl->x = p[0];
    }
    if(p.size() > 1){
        this->p_impl->y = p[1];
    }
    if(p.size() > 2){
        this->p_impl->z = p[2];
    }
    if(p.size() > 3){
        this->p_impl->t = p[3];
    }

    double result = this->p_impl->expression->value();

    return result;
}