source: cpp/frams/genetics/fL/fL_matheval.h @ 780

#ifndef _FL_MATHEVAL_H_
#define _FL_MATHEVAL_H_

#include <string>
#include <unordered_map>
#include <list>
#include <vector>

#define VARIABLEPREFIX '$'

/** @name Available operators for MathEvaluation */
//@{
double madd(double left, double right); ///<add
double msub(double left, double right); ///<subtract
double mmul(double left, double right); ///<multiply
double mand(double left, double right); ///<and
double mor(double left, double right); ///<or
double mgreater(double left, double right); ///<greater than
double mless(double left, double right); ///<less than
double mequal(double left, double right); ///<equal to
double mnotequal(double left, double right); ///<not equal to
double meqless(double left, double right); ///<less or equal
double meqgreater(double left, double right); ///<greater or equal
//@}

/**
 * Class for performing simple mathematical parsing and evaluations of expressions
 * stored in strings. At first, the class object converts given string into list
 * of objects that can be described as Reverse Polish Notation, or suffix notation.
 * From this notation object can efficiently perform calculations for different
 * values of variables, without re-tokenizing of a string.
 */
class MathEvaluation
{
        /// determines to whih class token belongs
        enum TokenType {
                NUMBER, ///<Number token
                PARENTHESIS, ///<Parenthesis token
                OPERATOR,  ///<Operator token
                VARIABLE ///<Variable token
        };
        /// associativity of operator
        enum Associativity {
                RIGHT,
                LEFT
        };
        /// determines if parenthesis is opening of closing
        enum ParenthesisType {
                OPEN,
                CLOSE
        };

        /**
         * Simplest token of MathEvaluation Reverse Polish Notation. Every class used
         * in RPN notation should inherit from this class.
         */
        class Token
        {
        public:
                TokenType type; ///<type of token
                /**
                 * Method is used during converting list of token objects into infix
                 * notation. Every class should implement this method and provide useful
                 * and valid information for infix notation.
                 * @return stringified token
                 */
                virtual std::string toString() = 0;
                Token(TokenType type) : type(type) {}
                virtual ~Token() {}
        };

        /**
         * Describes all numbers available in object infix notation.
         */
        class Number : public Token
        {
        public:
                double value; ///<value of stored number
                Number(double value) : Token(TokenType::NUMBER), value(value)
                { }
                ~Number() {}
                std::string toString();
                /**
                 * Copies value field from given source.
                 * @param src other Number object
                 */
                void operator=(const Number& src);
        };

        /**
         * Special type of Number object, which holds external variables, represented
         * as $id, where id is a number.
         */
        class Variable : public Number
        {
        public:
                int id; ///<id of Variable object. Object is accessed via $id
                Variable(int id) : Number(0), id(id)
                {
                        type = TokenType::VARIABLE;
                }
                ~Variable() {}
                std::string toString();
        };

        /**
         * Class describing operator in RPN objects. It holds informations about
         * precedence, associativity and symbol of the operator. Operator can have 1
         * or 2 characters, not more or less. Operator requires function that takes
         * two doubles and returns double value -- the result of this function is the
         * result of operator execution.
         */
        class Operator : public Token
        {
                double(*operation)(double left, double right); ///<field holding pointer to operator function
        public:
                int precedence; ///<precedence of the operator
                Associativity assoc; ///<associativity of the operator
                std::string opname; ///<symbol of the operator, can have 1 or 2 characters

                /**
                 * Uses method pointed by 'operation' pointer to return operator result
                 * for a given numbers.
                 * @param left number on the left side of the operator
                 * @param right number on the right side of the operator
                 * @return operator result
                 */
                double execute(double left, double right);

                Operator(double(*operation)(double left, double right), int precedence,
                        Associativity assoc, std::string opname) :
                        Token(TokenType::OPERATOR),
                        operation(operation),
                        precedence(precedence),
                        assoc(assoc),
                        opname(opname)
                { }
                ~Operator() {}
                std::string toString();
        };

        /**
         * Class represents parenthesis token. Parenthesis are considered only during
         * creation of RPN notation - the notation itself does not contain any
         * parenthesis, because the order of calculation is determined directly by
         * operators and numbers order.
         */
        class Parenthesis : public Token
        {
        public:
                ParenthesisType ptype; ///<determines if parenthesis is open or closed
                Parenthesis(ParenthesisType ptype) :
                        Token(TokenType::PARENTHESIS),
                        ptype(ptype)
                { }
                ~Parenthesis() { }
                std::string toString();
        };

        /**
         * Clears postfix objects stored in MathEvaluation object.
         */
        void clearPostfix();

        /**
         * Registers operators available in MathEvaluation object. Default operators
         * are +, -, *, &, |, >, <, >=, <=, =, ~, where ~ is inequality.
         * Registered operators can have maximally two characters, otherwise they are
         * ignored.
         */
        void registerOperators();

        std::unordered_map<std::string, Operator *> operators; ///<map containing available operators for MathEvaluation
        std::list<Token *> postfixlist; ///<list with tokens ordered as postfix (RPN) notation of the given string
        int varcount; ///<amount of variables declared for this MathEvaluation object
        std::vector<Variable *> vars; ///<vector of variables, default values are 0
        Variable *t; ///<additional t variable, that can act as time for evaluation
public:

        /**
         * Default constructor. It registers operators for MathEvaluation and prepares
         * vector of variables.
         */
        MathEvaluation(int varcount);

        /**
         * Destructor is responsible for clearing all objects in postfix, all operator
         * objects and all variables.
         */
        ~MathEvaluation();

        /**
         * Converts string to std::list of tokens in postfix order that can be later
         * evaluated. Detailed description of algorithm can be found in source of
         * method.
         * @param expression infix mathematical expression
         * @return 0 if conversion is successful, or -1 if an error occurred
         */
        int convertString(std::string expression);

        /**
         * Evaluates expression stored in postfix list. It takes into account changes
         * made by modifyVariable method. This method should be called if the only
         * thing changed in expression are variable values - it saves time because
         * it uses objects created during convertString or evaluate method.
         * @param res reference to the variable, in which result will be stored
         * @return 0 if evaluation went successful, or -1 if an error occurred
         */
        int evaluateRPN(double &res);

        /**
         * Performs convertString and evaluateRPN methods respectively. It holds
         * objects created by convertString method.
         * @param expression infix mathematical expression
         * @param result reference to the variable, in which result will be stored
         * @return 0 if evaluation went successful, otherwise it returns the error of previous functions
         */
        int evaluate(std::string expression, double &result);

        /**
         * Sets variable with index i with value val.
         * @param i id of variable, -1 if changed variable should be variable 't' (time)
         * @param val new value
         */
        void modifyVariable(int i, double val);

        /**
         * Converts stored RPN list to infix string.
         * @param result reference to variable that will hold the result
         * @return 0 if method went successful, or -1 if an error occurred
         */
        int RPNToInfix(std::string &result);
};

#endif // _FL_MATHEVAL_H_