137 lines
3.1 KiB
C++
137 lines
3.1 KiB
C++
#include "RPN.hpp"
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#include <algorithm>
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#include <iostream>
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#include <iterator>
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#include <sstream>
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#include <list>
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#include <string>
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/**
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* @brief Check if the input string is valid
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*
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* @param str input of the user
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* @return true if the input is valid
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*/
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bool check_input(std::string str) {
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std::string allowed = "0123456789 +-*/";
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for (std::string::const_iterator it = str.begin(); it != str.end(); ++it) {
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if (allowed.find(*it) == std::string::npos)
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return false;
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}
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return true;
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}
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/**
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* @brief split the input string into a list of tokens
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*
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* @param input input of the user (already checked)
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* @return std::list<tok> list of tokens
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*/
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std::list<tok> split_to_list(const std::string& input) {
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std::istringstream iss(input);
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std::string token;
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std::list<tok> tokens;
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e_op op;
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int tmp;
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while (iss >> token) {
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op = NUM;
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tmp = 0;
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if (token == "*") {
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op = MUL;
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}
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else if (token == "/") {
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op = DIV;
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}
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else if (token == "+") {
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op = ADD;
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}
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else if (token == "-") {
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op = SUB;
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}
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else {
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op = NUM;
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tmp = std::strtol(token.c_str(), 0, 10);
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}
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tok to_push = {op, tmp};
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tokens.push_back(to_push);
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}
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return tokens;
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}
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/**
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* @brief Execute the RPN algorithm
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*
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* @param tokens list of tokens
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* @return true if the execution was successful
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*/
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bool exec_rpn(std::list<tok> tokens) {
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if (tokens.size() < 3) {
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std::cerr << CLR_RED << "Error:\tNot enough operands" << CLR_RESET << std::endl;
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return false;
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}
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std::list<int> numbers;
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while (!tokens.empty()) {
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tok current = tokens.front();
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tokens.pop_front();
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if (current.type == NUM) {
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numbers.push_back(current.value);
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}
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else if (current.type == ADD || current.type == SUB || current.type == MUL || current.type == DIV) {
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if (numbers.size() < 2) {
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std::cerr << CLR_RED << "Error:\tNot enough operands for operator" << CLR_RESET << std::endl;
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return false;
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}
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int b = numbers.back();
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numbers.pop_back();
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int a = numbers.back();
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numbers.pop_back();
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if (current.type == ADD)
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numbers.push_back(a + b);
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else if (current.type == SUB)
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numbers.push_back(a - b);
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else if (current.type == MUL)
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numbers.push_back(a * b);
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else if (current.type == DIV) {
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if (b == 0) {
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std::cerr << CLR_RED << "Error:\tDivision by zero" << CLR_RESET << std::endl;
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return false;
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}
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numbers.push_back(a / b);
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}
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}
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else {
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std::cerr << CLR_RED << "Error:\tInvalid token" << CLR_RESET << std::endl;
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return false;
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}
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}
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if (numbers.size() != 1) {
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std::cerr << CLR_RED << "Error:\tInvalid final stack state" << CLR_RESET << std::endl;
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return false;
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}
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std::cout << CLR_GREEN << "Result:\t" << numbers.back() << CLR_RESET << std::endl;
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return true;
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}
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int main(int argc, char **argv) {
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if (argc != 2) {
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std::cerr << CLR_RED << "Usage:\t" << argv[0] << " <string>" << CLR_RESET << std::endl;
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return 1;
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}
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std::string input = argv[1];
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if (!check_input(input)) {
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std::cerr << CLR_RED << "Error:\tYour input can only have digits, spaces and the operators '+' '-' '*' '/'" << CLR_RESET << std::endl;
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return 1;
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} else {
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std::list<tok> tokens = split_to_list(input);
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exec_rpn(tokens);
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}
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}
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