evaluator.cpp

#include "evaluator.h"
#include <stack>
#include <cmath>
#include <stdexcept>

double Evaluator::evaluate(const std::vector<Token>& postfix) {
    std::stack<double> stack;

    for (const Token& tok : postfix) {
        if (tok.type == TokenType::NUMBER) {
            stack.push(tok.number);
        }
        else if (tok.type == TokenType::VARIABLE) {
            stack.push(variables.get(tok.value));
        }
        else if (tok.type == TokenType::OPERATOR) {
            if (tok.value == "u-") {
                double a = stack.top(); stack.pop();
                stack.push(-a);
                continue;
            }
            double b = stack.top(); stack.pop();
            double a = stack.top(); stack.pop();
            stack.push(applyOp(tok.value, a, b));
        }
        else if (tok.type == TokenType::FUNCTION) {
            double arg = stack.top(); stack.pop();
            stack.push(applyFunc(tok.value, arg));
        }
    }

    return stack.top();
}

double Evaluator::applyOp(const std::string& op, double a, double b) const {
    if (op == "+") return a + b;
    if (op == "-") return a - b;
    if (op == "*") return a * b;
    if (op == "%") return std::fmod(a, b);
    if (op == "^") return std::pow(a, b);
    if (op == "/") {
        if (b == 0) throw std::runtime_error("division by zero");
        return a / b;
    }
    throw std::runtime_error("unknown operator: " + op);
}

double Evaluator::applyFunc(const std::string& fn, double arg) const {
    if (fn == "sqrt") {
        if (arg < 0) throw std::runtime_error("sqrt of negative number");
        return std::sqrt(arg);
    }
    if (fn == "sin")  return std::sin(arg * M_PI / 180.0);
    if (fn == "cos")  return std::cos(arg * M_PI / 180.0);
    if (fn == "tan")  return std::tan(arg * M_PI / 180.0);
    if (fn == "log")  return std::log10(arg);
    if (fn == "log2") return std::log2(arg);
    if (fn == "ln")   return std::log(arg);
    if (fn == "abs")  return std::abs(arg);
    if (fn == "floor") return std::floor(arg);
    if (fn == "ceil") return std::ceil(arg);

    throw std::runtime_error("unknown function: " + fn);
}