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

#include <frams/util/extvalue.h>
#include <frams/util/sstring.h>
#include <stack>
#include "fL_matheval.h"

// Used available operators in MathEvaluation

double madd(double left, double right)
{
        return left + right;
}

double msub(double left, double right)
{
        return left - right;
}

double mmul(double left, double right)
{
        return left * right;
}

double mand(double left, double right)
{
        return left && right;
}

double mor(double left, double right)
{
        return left || right;
}

double mgreater(double left, double right)
{
        return left > right;
}

double mless(double left, double right)
{
        return left < right;
}

double mequal(double left, double right)
{
        return left == right;
}

double mnotequal(double left, double right)
{
        return left != right;
}

double meqless(double left, double right)
{
        return left <= right;
}

double meqgreater(double left, double right)
{
        return left >= right;
}

// Methods for converting evaluation tokens to string

std::string MathEvaluation::Number::toString()
{
        return std::string(SString::valueOf(value).c_str());
}

std::string MathEvaluation::Variable::toString()
{
        if (id == -1) return std::string(1, VARIABLEPREFIX) + "t";
        return std::string(1, VARIABLEPREFIX) + std::to_string(id);
}

std::string MathEvaluation::Parenthesis::toString()
{
        return ptype == ParenthesisType::OPEN ? "(" : ")";
}

std::string MathEvaluation::Operator::toString()
{
        return opname;
}

void MathEvaluation::Number::operator=(const Number& src)
{
        value = src.value;
}

double MathEvaluation::Operator::execute(double left, double right)
{
        return operation(left, right);
}

void MathEvaluation::registerOperators()
{
        // list of available operators in MathEvaluation
        operators["+"] = new Operator(madd, 2, Associativity::LEFT, "+");
        operators["-"] = new Operator(msub, 2, Associativity::LEFT, "-");
        operators["*"] = new Operator(mmul, 3, Associativity::LEFT, "*");
        operators["&"] = new Operator(mand, 0, Associativity::LEFT, "&");
        operators["|"] = new Operator(mor, 0, Associativity::LEFT, "|");
        operators[">"] = new Operator(mgreater, 1, Associativity::LEFT, ">");
        operators["<"] = new Operator(mless, 1, Associativity::LEFT, "<");
        operators[">="] = new Operator(meqgreater, 1, Associativity::LEFT, ">=");
        operators["<="] = new Operator(meqless, 1, Associativity::LEFT, "<=");
        operators["="] = new Operator(mequal, 1, Associativity::RIGHT, "=");
        operators["~"] = new Operator(mnotequal, 1, Associativity::RIGHT, "~");
}

void MathEvaluation::clearPostfix()
{
        if (!postfixlist.empty())
        {
                for (Token *el : postfixlist)
                {
                        // only numbers or parenthesis should be removed - operators and
                        // variables are removed later during destruction of the
                        // MathEvaluation object
                        if (el->type == TokenType::NUMBER ||
                                el->type == TokenType::PARENTHESIS)
                                delete el;
                }
                postfixlist.clear();
        }
}

MathEvaluation::MathEvaluation(int varcount) : varcount(varcount), vars(varcount, NULL)
{
        registerOperators();
        for (int i = 0; i < varcount; i++)
        {
                vars[i] = new Variable(i);
        }
        t = new Variable(-1);
        t->value = 0;
}

MathEvaluation::~MathEvaluation()
{
        clearPostfix();

        std::unordered_map<std::string, Operator *>::iterator it;
        for (it = operators.begin(); it != operators.end(); it++)
        {
                delete it->second;
        }
        operators.clear();

        for (Variable *var : vars)
        {
                delete var;
        }
        vars.clear();
        delete t;
}

int MathEvaluation::convertString(std::string expression)
{
        clearPostfix(); //clear previous objects
        ExtValue val;

        unsigned int it = 0;

        std::list<Token*> operatorstack; // stores operators for later

        bool canbeunary = true; // used to determine if -/+ operators should be unary
        while (it < expression.size())
        {
                bool parsenumber = false;
                int oplen = 2; // first method checks if 2-character operators match, then 1-character

                // if following letters describe variable
                if (expression[it] == VARIABLEPREFIX ||
                        (canbeunary && strchr("+-", expression[it]) &&
                        it + 1 < expression.size() &&
                        expression[it + 1] == VARIABLEPREFIX))
                {
                        // determine if before variable there is an unary operator '-'
                        // if yes, the variable will be negated
                        double mult = expression[it] == '-' ? -1 : 1;
                        it += expression[it] == VARIABLEPREFIX ? 1 : 2;
                        // if there is no space after '$' character, return error
                        if (it >= expression.size())
                        {
                                std::string message = "Evaluation error: Invalid variable '";
                                message += expression.substr(it) + "'";
                                logMessage("MathEvaluation", "convertString", LOG_ERROR, message.c_str());
                                while (!operatorstack.empty())
                                {
                                        if (operatorstack.back()->type != TokenType::OPERATOR)
                                        {
                                                delete operatorstack.back();
                                                operatorstack.pop_back();
                                        }
                                }
                                return -1;
                        }

                        //determine id of variable
                        const char *ptr = expression[it] == 't' ? expression.c_str() + it + 1 : val.parseNumber(expression.c_str() + it, ExtPType::TInt);
                        int index = expression[it] == 't' ? -1 : val.getInt();
                        bool invalidid = false;
                        // if id is parsed properly
                        if (ptr) // if current element is number, then add it to RPN
                        {
                                // if id is exceeding available amount of variables, then variable
                                // is invalid
                                if (index >= varcount)
                                {
                                        invalidid = true;
                                }
                                else
                                {
                                        Variable *v = index == -1 ? t : vars[index];
                                        // if variable had unary '-', then is multiplied by -1
                                        // multiplying value stored in variable would change value
                                        // in every occurrence of variable
                                        if (mult == -1)
                                        {
                                                postfixlist.push_back(new Number(-1));
                                                postfixlist.push_back(v);
                                                postfixlist.push_back(operators["*"]);
                                        }
                                        // push pointer to a variable in order to make evaluation
                                        // reusable for other values of variables
                                        else
                                        {
                                                postfixlist.push_back(v);
                                        }
                                        int offset = ptr - (expression.c_str() + it);
                                        it += offset;
                                        // after variable there cannot be unary operator
                                        canbeunary = false;
                                }
                        }
                        // if parsing of variable went wrong, then return error message
                        if (!ptr || invalidid)
                        {
                                std::string message = "Evaluation error: Invalid variable '";
                                message += expression.substr(it) + "'";
                                logMessage("MathEvaluation", "convertString", LOG_ERROR, message.c_str());
                                while (!operatorstack.empty())
                                {
                                        if (operatorstack.back()->type != TokenType::OPERATOR)
                                        {
                                                delete operatorstack.back();
                                                operatorstack.pop_back();
                                        }
                                }
                                return -1;
                        }
                }
                // if current characters describe operators
                else if ((it + 1 < expression.size() && operators.find(expression.substr(it, oplen)) != operators.end())
                        || operators.find(expression.substr(it, --oplen)) != operators.end())
                {
                        // if operator is + or - and from context it is known that it is
                        // unary version of one of those operators, then move control to
                        // number parsing
                        if (canbeunary && strchr("+-", expression[it]) &&
                                it + 1 < expression.size() && isdigit(expression[it + 1]))
                        {
                                parsenumber = true;
                        }
                        else
                        {
                                // otherwise prepare pointer to a given operator
                                Operator *newop = operators[expression.substr(it, oplen)];

                                bool finished = operatorstack.empty();

                                // before operator will be put onto the operator stack, all operators
                                // with higher precedence than the current operator should be popped
                                // from the stack and added to postfix list
                                while (!finished)
                                {

                                        Token *curr = operatorstack.back();
                                        // when token in the operator stack is opened parenthesis,
                                        // then the process of taking operators from stack stops.
                                        if (curr->type == TokenType::PARENTHESIS)
                                        {
                                                Parenthesis *par = (Parenthesis *)curr;
                                                if (par->ptype == ParenthesisType::OPEN)
                                                {
                                                        finished = true;
                                                }
                                        }
                                        else
                                        {
                                                // if current operator in stack is left-associated and
                                                // its precedence is equal or greater than precedence of
                                                // new operator than current operator is taken from stack
                                                // and added to postfixlist. If current operator is
                                                // right-associated, then its precedence must be strictly
                                                // higher than new operator precedence
                                                Operator *op = (Operator *)curr;
                                                if (newop->assoc == Associativity::LEFT && newop->precedence <= op->precedence)
                                                {
                                                        postfixlist.push_back(op);
                                                        operatorstack.pop_back();
                                                }
                                                else if (newop->assoc == Associativity::RIGHT && newop->precedence < op->precedence)
                                                {
                                                        postfixlist.push_back(op);
                                                        operatorstack.pop_back();
                                                }
                                                else
                                                {
                                                        finished = true;
                                                }
                                        }
                                        finished = finished || operatorstack.empty();
                                }
                                // after operator there cannot be unary operator - wrap it in
                                // parenthesis
                                canbeunary = false;
                                // add new operator to stack
                                operatorstack.push_back(newop);
                                it += oplen;
                        }
                }
                else if (expression[it] == '(' || expression[it] == ')')
                {
                        // if current character is open parenthesis, then add it to
                        // the operator stack
                        if (expression[it] == '(')
                        {
                                Parenthesis *par = new Parenthesis(ParenthesisType::OPEN);
                                // after open parenthesis there can be unary operator
                                canbeunary = true;
                                operatorstack.push_back(par);
                        }
                        else
                        {
                                // if current character is closed parenthesis, then all operators
                                // are popped from stack into postfix list until first open
                                // parenthesis is found
                                bool finpop = false;
                                while (!finpop)
                                {
                                        // if there is no more operators in the stack, then parenthesis
                                        // is mismatched
                                        if (operatorstack.empty())
                                        {
                                                logMessage("MathEvaluation", "convertString", LOG_ERROR, "Evaluation error: Parenthesis mismatch");
                                                return -1;
                                        }
                                        Token *curr = operatorstack.back();
                                        if (curr->type == TokenType::PARENTHESIS)
                                        {
                                                // if corresponding parenthesis is found, then opening
                                                // parenthesis is deleted and removed from stack - postfix
                                                // notation does not have parenthesis
                                                Parenthesis *par = (Parenthesis *)curr;
                                                if (par->ptype == ParenthesisType::OPEN)
                                                {
                                                        delete par;
                                                        operatorstack.pop_back();
                                                        finpop = true;
                                                }
                                        }
                                        else
                                        {
                                                postfixlist.push_back(curr);
                                                operatorstack.pop_back();
                                        }
                                }
                                // after closed parenthesis unary operators does not exist
                                canbeunary = false;
                        }
                        it++;
                }
                else if (isspace(expression[it])) // all whitespaces are skipped
                {
                        it++;
                }
                else // if above conditions are not satisfied, then method assumes that
                {    // characters describe number
                        parsenumber = true;
                }
                if (parsenumber)
                {
                        // if parsing went successfully, then push number to postfix list
                        const char *ptr = val.parseNumber(expression.c_str() + it, ExtPType::TDouble);
                        if (ptr) // if current element is number, then add it to RPN
                        {
                                Number *num = new Number(val.getDouble());
                                postfixlist.push_back(num);
                                int offset = ptr - (expression.c_str() + it);
                                it += offset;
                                // There are no unary operators after number
                                canbeunary = false;
                        }
                        else
                        {
                                // otherwise return error
                                std::string message = "Evaluation error: Invalid letter '";
                                message += expression[it];
                                message += "'";
                                logMessage("MathEvaluation", "convertString", LOG_ERROR, message.c_str());
                                while (!operatorstack.empty())
                                {
                                        if (operatorstack.back()->type != TokenType::OPERATOR)
                                        {
                                                delete operatorstack.back();
                                                operatorstack.pop_back();
                                        }
                                }
                                return -1;
                        }
                }
        }

        // Pop remaining operators from stack and add them to the postfix list
        while (!operatorstack.empty())
        {
                Token *curr = operatorstack.back();
                if (curr->type == TokenType::OPERATOR)
                {
                        postfixlist.push_back(curr);
                        operatorstack.pop_back();
                }
                else
                {
                        // if current token in the stack is open parenthesis, then mismatch
                        // occured
                        logMessage("MathEvaluation", "convertString", LOG_ERROR, "Evaluation error: Parenthesis mismatch");
                        while (!operatorstack.empty())
                        {
                                if (operatorstack.back()->type != TokenType::OPERATOR)
                                {
                                        delete operatorstack.back();
                                        operatorstack.pop_back();
                                }
                        }
                        return -1;
                }
        }

        return 0;
}

int MathEvaluation::evaluateRPN(double &res)
{
        // stack holds number used during operator execution
        std::stack<Number *> numberstack;

        for (std::list<Token *>::iterator it = postfixlist.begin(); it != postfixlist.end(); it++)
        {
                Token *tok = (*it);
                // if token is number or variable - add it to number stack
                if (tok->type == TokenType::NUMBER || tok->type == TokenType::VARIABLE)
                {
                        Number *num = new Number(((Number *)tok)->value);
                        numberstack.push(num);
                }
                else
                {
                        // the token is an operator
                        Operator *op = (Operator *)tok;
                        // if there isn't at least 2 elements in number stack, then return error
                        if (numberstack.size() < 2)
                        {
                                logMessage("MathEvaluation", "convertString", LOG_ERROR, "Evaluation error: The math expression is not complete");
                                while (!numberstack.empty())
                                {
                                        if (numberstack.top()->type == TokenType::NUMBER) delete numberstack.top();
                                        numberstack.pop();
                                }
                                return -1;
                        }
                        // otherwise, pop two top elements from number stack and use them
                        // with current operator
                        double right = numberstack.top()->value;
                        if (numberstack.top()->type == TokenType::NUMBER) delete numberstack.top();
                        numberstack.pop();
                        double left = numberstack.top()->value;
                        if (numberstack.top()->type == TokenType::NUMBER) delete numberstack.top();
                        numberstack.pop();
                        double result = op->execute(left, right);
                        Number *newnum = new Number(result);
                        // Push operation result to number stack
                        numberstack.push(newnum);
                }
        }

        // in the end of processing, only 1 element should be available in number stack.
        // Otherwise expression was not complete and error will be returned
        if (numberstack.size() != 1)
        {
                logMessage("MathEvaluation", "convertString", LOG_ERROR, "Evaluation error: The math expression is not complete");
                while (!numberstack.empty())
                {
                        if (numberstack.top()->type == TokenType::NUMBER) delete numberstack.top();
                        numberstack.pop();
                }
                return -1;
        }

        res = numberstack.top()->value;
        if (numberstack.top()->type == TokenType::NUMBER) delete numberstack.top();
        numberstack.pop();
        return 0;
}

void MathEvaluation::modifyVariable(int i, double val)
{
        if (i == -1)
        {
                t->value = val;
        }
        else
        {
                if (!vars[i])
                {
                        vars[i] = new Variable(i);
                }
                vars[i]->value = val;
        }
}

int MathEvaluation::evaluate(std::string expression, double &result)
{
        int res = convertString(expression);
        if (res != 0) return res;
        return evaluateRPN(result);
}

int MathEvaluation::RPNToInfix(std::string &result)
{
        // stack holds stringified chunk and its precedence
        std::stack<std::pair<std::string, int>> chunks;
        // foreach token in postfix list
        for (Token *tok : postfixlist)
        {
                // if token is not an operator, push stringified variable or number
                // on top of stack
                if (tok->type != TokenType::OPERATOR)
                {
                        // number or variable has no precedence
                        chunks.push({ tok->toString(), -1 });
                }
                else // if token is an operator
                {
                        Operator *op = (Operator *)tok;
                        int prec = op->precedence;
                        // if there are not at least two stringified chunks in stack, return error
                        if (chunks.size() < 2)
                        {
                                logMessage("MathEvaluation", "RPNToInfix", LOG_ERROR,
                                        "Could not convert RPN notation to infix notation");
                                return -1;
                        }
                        // pop first chunk
                        std::pair<std::string, int> right = chunks.top();
                        chunks.pop();
                        if (right.second != -1 && right.second < op->precedence)
                        {
                                // if chunk on the right of operator has lower precedence than
                                // this operator, then wrap it with parenthesis
                                right.first = std::string(1, '(') + right.first + std::string(1, ')');
                        }
                        else if (right.second >= op->precedence)
                        {
                                prec = right.second;
                        }
                        std::pair<std::string, int> left = chunks.top();
                        chunks.pop();
                        if (left.second != -1 && left.second < op->precedence)
                        {
                                // if chunk on the left of operator has lower precedence than
                                // this operator, then wrap it with parenthesis
                                left.first = std::string(1, '(') + left.first + std::string(1, ')');
                        }
                        std::string res = left.first + op->toString() + right.first;
                        // add summed chunk
                        chunks.push({ res, prec });
                }
        }
        // if there is more than one chunk then return error
        if (chunks.size() != 1)
        {
                logMessage("MathEvaluation", "RPNToInfix", LOG_ERROR,
                        "Could not convert RPN notation to infix notation");
                return -1;
        }
        result = chunks.top().first;
        chunks.pop();
        return 0;
}