initial calculator

Author: c71n93

week-15/CMakeLists.txt

@@ -1,4 +1,4 @@
-set(DIRS task-12-14 task-12-15)
+set(DIRS task-12-14 task-12-15 task-12-20)
 foreach(DIR ${DIRS})
     add_subdirectory(${DIR})
 endforeach()

week-15/task-12-20/CMakeLists.txt

@@ -0,0 +1,5 @@
+include_directories(include)
+
+add_subdirectory(test)
+
+add_executable(ae main.cpp)

week-15/task-12-20/include/calculator.hpp

@@ -0,0 +1,46 @@
+#pragma once
+
+#include <stack>
+#include <sstream>
+
+bool is_operator(char c) {
+    return c == '+' || c == '-' || c == '*' || c == '/';
+}
+
+int calculate(const std::string& str) {
+    std::stack<int> stack;
+    for (auto it = std::cbegin(str); it != std::cend(str);) {
+        if (static_cast<bool>(std::isspace(*it))) {
+            while (it != std::cend(str) && static_cast<bool>(std::isspace(*it))) { ++it; }
+        } else if (static_cast<bool>(std::isdigit(*it))) {
+            std::istringstream iss(std::string(it, std::cend(str)));
+            int val;
+            iss >> val;
+            stack.push(val);
+            std::advance(it, iss.tellg());
+        } else if (is_operator(*it)) {
+            const int b = stack.top(); stack.pop();
+            const int a = stack.top(); stack.pop();
+            switch (*it) {
+                case '+':
+                    stack.push(a + b);
+                    break;
+                case '-':
+                    stack.push(a - b);
+                    break;
+                case '*':
+                    stack.push(a * b);
+                    break;
+                case '/':
+                    stack.push(a / b);
+                    break;
+                default:
+                    throw std::runtime_error("unexpected operator");
+            }
+            ++it;
+        } else {
+            throw std::runtime_error("unexpected symbol");
+        }
+    }
+    return stack.top();
+}

week-15/task-12-20/main.cpp

@@ -0,0 +1,5 @@
+#include "calculator.hpp"
+
+int main() {
+    calculate("3 4 +");
+}

week-15/task-12-20/test/CMakeLists.txt

@@ -0,0 +1 @@
+cpp_test(test-12-20.cpp)

week-15/task-12-20/test/test-12-20.cpp

@@ -0,0 +1,43 @@
+#include "gtest/gtest.h"
+#include "calculator.hpp"
+
+TEST(RPNCalculatorTest, BasicOperations) {
+    EXPECT_EQ(calculate("3 4 +"), 7);      // 3 + 4
+    EXPECT_EQ(calculate("5 2 -"), 3);      // 5 - 2
+    EXPECT_EQ(calculate("2 3 *"), 6);      // 2 * 3
+    EXPECT_EQ(calculate("6 2 /"), 3);      // 6 / 2
+}
+
+TEST(RPNCalculatorTest, ComplexExpressions) {
+    EXPECT_EQ(calculate("3 4 2 * +"), 11);     // 3 + (4 * 2)
+    EXPECT_EQ(calculate("5 1 2 + 4 * + 3 -"), 14); // 5 + ((1+2)*4) - 3
+    EXPECT_EQ(calculate("4 2 5 * + 1 3 - /"), -7); // (4 + 2*5) / (1-3)
+}
+
+TEST(RPNCalculatorTest, EdgeCases) {
+    EXPECT_EQ(calculate("0 5 +"), 5);       // 0 + 5
+    EXPECT_EQ(calculate("1 1 -"), 0);       // 1 - 1
+    EXPECT_EQ(calculate("999 1 +"), 1000);  // large number
+    EXPECT_EQ(calculate("-5 3 +"), -2);     // negative number
+}
+
+TEST(RPNCalculatorTest, InvalidInput) {
+    EXPECT_THROW(calculate(""), std::invalid_argument);      // empty
+    EXPECT_THROW(calculate("3 +"), std::invalid_argument);   // missing operand
+    EXPECT_THROW(calculate("3 4 + -"), std::invalid_argument); // extra operator
+    EXPECT_THROW(calculate("a b +"), std::invalid_argument); // non-numbers
+    EXPECT_THROW(calculate("3 0 /"), std::runtime_error);    // division by zero
+}
+
+TEST(RPNCalculatorTest, WhitespaceHandling) {
+    EXPECT_EQ(calculate("  3   4  +  "), 7);  // extra spaces
+    EXPECT_EQ(calculate("3\n4\t+"), 7);       // different whitespace
+    EXPECT_EQ(calculate("3 4 + "), 7);        // trailing space
+}
+
+TEST(RPNCalculatorTest, MultiDigitNumbers) {
+    EXPECT_EQ(calculate("10 20 +"), 30);      // 10 + 20
+    EXPECT_EQ(calculate("100 50 -"), 50);     // 100 - 50
+    EXPECT_EQ(calculate("12 34 *"), 408);     // 12 * 34
+    EXPECT_EQ(calculate("100 5 /"), 20);      // 100 / 5
+}