[4기 - 전선희] 1~2주차 과제 : 계산기 구현 미션 제출합니다. (2차)

src/main/java/com/programmers/App.java

@@ -1,14 +1,15 @@
 package com.programmers;
 
 import com.programmers.engine.JavaCalculator;
-import com.programmers.engine.model.Result;
+import com.programmers.engine.model.ResultManager;
+import com.programmers.engine.module.BasicCalculator;
 
 public class App {
     public static void main(String[] args) {
         Console console = new Console();
-        Result result = new Result();
+        ResultManager resultManager = new ResultManager();
         BasicCalculator bc = new BasicCalculator();
 
-        new JavaCalculator(console, console, result, bc).run();
+        new JavaCalculator(console, console, resultManager, bc).run();
     }
 }

src/main/java/com/programmers/Console.java

@@ -3,6 +3,7 @@
 import com.programmers.engine.io.Input;
 import com.programmers.engine.io.Output;
 
+import java.util.Map;
 import java.util.Scanner;
 
 public class Console implements Input, Output {
@@ -28,4 +29,20 @@ public String getExpression() {
         System.out.println("계산하고자 하는 식을 입력해주세요!");
         return sc.nextLine();
     }
+
+    @Override
+    public void readAllResults(Map<Integer, String> map) {
+        if (map.isEmpty()) {
+            System.out.println("계산 이력이 없습니다.");
+            return;
+        }
+        System.out.println();
+        map.forEach((key, value) -> System.out.println(value));
+        System.out.println();
+    }
+
+    @Override
+    public void printAnswer(int answer) {
+        System.out.println(answer);
+    }
 }

src/main/java/com/programmers/engine/JavaCalculator.java

@@ -1,29 +1,40 @@
 package com.programmers.engine;
 
-import com.programmers.BasicCalculator;
+import com.programmers.engine.module.BasicCalculator;
 import com.programmers.engine.io.Input;
 import com.programmers.engine.io.Output;
-import com.programmers.engine.model.Result;
+import com.programmers.engine.model.Menu;
+import com.programmers.engine.model.ResultManager;
 import lombok.AllArgsConstructor;
 
 @AllArgsConstructor
 public class JavaCalculator implements Runnable{
     private final Input input;
     private final Output output;
-    private final Result result;
+    private final ResultManager resultManager;
     private final BasicCalculator bc;
 
     @Override
     public void run() {
-        boolean isExecutable = true;
-        while (isExecutable) {
+        while (true) {
             output.showMenu();
-            switch (input.selectMenu()) {
-                case 1 -> result.readAllResults();
-                case 2 -> result.save(bc.doCalculate(input.getExpression()));
-                case 3 -> isExecutable = false;
+            Menu menu = Menu.matchMenu(input.selectMenu());
+
+            switch (menu) {
+                case LOOK_UP -> output.readAllResults(resultManager.readAllResults());
+                case CALCULATE -> calculate();
+                case EXIT -> {
+                    return;
+                }
                 default -> output.inputError();
             }
         }
     }
+
+    private void calculate() {
+        String expression = input.getExpression();
+        int answer = bc.doCalculate(expression);
+        output.printAnswer(answer);
+        resultManager.save(expression, answer);
+    }
 }

src/main/java/com/programmers/engine/io/Output.java

@@ -1,6 +1,10 @@
 package com.programmers.engine.io;
 
+import java.util.Map;
+
 public interface Output {
     void showMenu();
     void inputError();
+    void readAllResults(Map<Integer, String> map);
+    void printAnswer(int answer);
 }

src/main/java/com/programmers/engine/model/Menu.java

@@ -0,0 +1,22 @@
+package com.programmers.engine.model;
+
+import java.util.Arrays;
+
+public enum Menu {
+    LOOK_UP("1"),
+    CALCULATE("2"),
+    EXIT("3");
+
+    private final String menu;
+
+    Menu(String menu) {
+        this.menu = menu;
+    }
+
+    public static Menu matchMenu(int number) {
+        return Arrays.stream(values())
+                .filter(v -> number == Integer.parseInt(v.menu))
+                .findFirst()
+                .orElseThrow(IllegalStateException::new);
+    }
+}

src/main/java/com/programmers/engine/model/Operator.java

@@ -0,0 +1,35 @@
+package com.programmers.engine.model;
+
+import lombok.Getter;
+
+import java.util.Arrays;
+import java.util.function.BiFunction;
+
+@Getter
+public enum Operator {
+    ADD("+", 1, (a, b) -> a + b),
+    SUBTRACTION("-", 1, (a, b) -> a - b),
+    MULTIPLY("*", 2, (a, b) -> a * b),
+    DIVIDE("/", 2, (a, b) -> b / a);
+
+    private final String symbol;
+    private final int priority;
+    private final BiFunction<Integer, Integer, Integer> action;
+
+    Operator(String symbol, int priority, BiFunction<Integer, Integer, Integer> action) {
+        this.symbol = symbol;
+        this.priority = priority;
+        this.action = action;
+    }
+
+    public static Operator matchOperator(String operator) {
+        return Arrays.stream(values())
+                .filter(v -> operator.equals(v.symbol))
+                .findFirst()
+                .orElseThrow(IllegalArgumentException::new);
+    }
+
+    public int calculate(int a, int b) {
+        return action.apply(a, b);
+    }
+}

src/main/java/com/programmers/engine/model/ResultManager.java

@@ -0,0 +1,17 @@
+package com.programmers.engine.model;
+
+import java.util.HashMap;
+import java.util.Map;
+
+public class ResultManager {
+    private final Map<Integer, String> results = new HashMap<>();
+    private int key = 0;
+
+    public void save(String expression, int answer) {
+        results.put(++key, expression + " = " + String.valueOf(answer));
+    }
+
+    public Map<Integer, String> readAllResults() {
+        return results;
+    }
+}

src/main/java/com/programmers/engine/module/BasicCalculator.java

@@ -0,0 +1,16 @@
+package com.programmers.engine.module;
+
+import com.programmers.engine.module.convert.AnswerConverter;
+import com.programmers.engine.module.convert.PostfixConverter;
+import java.util.List;
+
+public class BasicCalculator {
+    private final PostfixConverter postfixConverter = new PostfixConverter();
+    private final AnswerConverter answerConverter = new AnswerConverter();
+
+    public int doCalculate(String expression) {
+        List<String> postfixList =  postfixConverter.convertInfixToPostfix(expression);
+        return answerConverter.convertPostfixToAnswer(postfixList);
+    }
+
+}

src/main/java/com/programmers/engine/module/convert/AnswerConverter.java

@@ -0,0 +1,23 @@
+package com.programmers.engine.module.convert;
+
+import com.programmers.engine.model.Operator;
+
+import java.util.List;
+import java.util.Stack;
+
+public class AnswerConverter {
+    public int convertPostfixToAnswer(List<String> list) {
+        Stack<Integer> st = new Stack<>();
+        for (String now : list) {
+            if (!now.equals("+") && !now.equals("-") && !now.equals("*") && !now.equals("/")) {
+                st.push(Integer.parseInt(now));
+                continue;
+            }
+            Operator operator = Operator.matchOperator(now);
+            int x = st.pop();
+            int y = st.pop();
+            st.push(operator.calculate(x, y));
+        }
+        return st.pop();
+    }
+}

src/main/java/com/programmers/engine/module/convert/PostfixConverter.java

@@ -0,0 +1,28 @@
+package com.programmers.engine.module.convert;
+
+import com.programmers.engine.model.Operator;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Stack;
+
+public class PostfixConverter {
+
+    public List<String> convertInfixToPostfix(String expression) {
+        String[] strArr = expression.split(" ");
+        List<String> output = new ArrayList<>();
+        Stack<String> st = new Stack<>();
+
+        for (String now: strArr) {
+            if (now.equals("+") || now.equals("-") || now.equals("*") || now.equals("/")) {
+                while (!st.isEmpty() && Operator.matchOperator(st.peek()).getPriority() >= Operator.matchOperator(now).getPriority()) {
+                    output.add(st.pop());
+                }
+                st.push(now);
+                continue;
+            }
+            output.add(now);
+        }
+        while (!st.isEmpty()) output.add(st.pop());
+        return output;
+    }
+}