feat: 계산기 구현

.gitattributes

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+#
+# https://help.github.com/articles/dealing-with-line-endings/
+#
+# Linux start script should use lf
+/gradlew        text eol=lf
+
+# These are Windows script files and should use crlf
+*.bat           text eol=crlf
+

.gitignore

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+# Created by https://www.toptal.com/developers/gitignore/api/java,gradle,intellij+all
+# Edit at https://www.toptal.com/developers/gitignore?templates=java,gradle,intellij+all
+
+### Intellij+all ###
+# Covers JetBrains IDEs: IntelliJ, RubyMine, PhpStorm, AppCode, PyCharm, CLion, Android Studio, WebStorm and Rider
+# Reference: https://intellij-support.jetbrains.com/hc/en-us/articles/206544839
+
+# User-specific stuff
+.idea/**/workspace.xml
+.idea/**/tasks.xml
+.idea/**/usage.statistics.xml
+.idea/**/dictionaries
+.idea/**/shelf
+
+# AWS User-specific
+.idea/**/aws.xml
+
+# Generated files
+.idea/**/contentModel.xml
+
+# Sensitive or high-churn files
+.idea/**/dataSources/
+.idea/**/dataSources.ids
+.idea/**/dataSources.local.xml
+.idea/**/sqlDataSources.xml
+.idea/**/dynamic.xml
+.idea/**/uiDesigner.xml
+.idea/**/dbnavigator.xml
+
+# Gradle
+.idea/**/gradle.xml
+.idea/**/libraries
+
+# Gradle and Maven with auto-import
+# When using Gradle or Maven with auto-import, you should exclude module files,
+# since they will be recreated, and may cause churn.  Uncomment if using
+# auto-import.
+# .idea/artifacts
+# .idea/compiler.xml
+# .idea/jarRepositories.xml
+# .idea/modules.xml
+# .idea/*.iml
+# .idea/modules
+# *.iml
+# *.ipr
+
+# CMake
+cmake-build-*/
+
+# Mongo Explorer plugin
+.idea/**/mongoSettings.xml
+
+# File-based project format
+*.iws
+
+# IntelliJ
+out/
+
+# mpeltonen/sbt-idea plugin
+.idea_modules/
+
+# JIRA plugin
+atlassian-ide-plugin.xml
+
+# Cursive Clojure plugin
+.idea/replstate.xml
+
+# SonarLint plugin
+.idea/sonarlint/
+
+# Crashlytics plugin (for Android Studio and IntelliJ)
+com_crashlytics_export_strings.xml
+crashlytics.properties
+crashlytics-build.properties
+fabric.properties
+
+# Editor-based Rest Client
+.idea/httpRequests
+
+# Android studio 3.1+ serialized cache file
+.idea/caches/build_file_checksums.ser
+
+### Intellij+all Patch ###
+# Ignore everything but code style settings and run configurations
+# that are supposed to be shared within teams.
+
+.idea/*
+
+!.idea/codeStyles
+!.idea/runConfigurations
+
+### Java ###
+# Compiled class file
+*.class
+
+# Log file
+*.log
+
+# BlueJ files
+*.ctxt
+
+# Mobile Tools for Java (J2ME)
+.mtj.tmp/
+
+# Package Files #
+*.jar
+*.war
+*.nar
+*.ear
+*.zip
+*.tar.gz
+*.rar
+
+# virtual machine crash logs, see http://www.java.com/en/download/help/error_hotspot.xml
+hs_err_pid*
+replay_pid*
+
+### Gradle ###
+.gradle
+**/build/
+!src/**/build/
+
+# Ignore Gradle GUI config
+gradle-app.setting
+
+# Avoid ignoring Gradle wrapper jar file (.jar files are usually ignored)
+!gradle-wrapper.jar
+
+# Avoid ignore Gradle wrappper properties
+!gradle-wrapper.properties
+
+# Cache of project
+.gradletasknamecache
+
+# Eclipse Gradle plugin generated files
+# Eclipse Core
+.project
+# JDT-specific (Eclipse Java Development Tools)
+.classpath
+
+### Gradle Patch ###
+# Java heap dump
+*.hprof
+
+# End of https://www.toptal.com/developers/gitignore/api/java,gradle,intellij+all

app/build.gradle

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+/*
+ * This file was generated by the Gradle 'init' task.
+ *
+ * This generated file contains a sample Java application project to get you started.
+ * For more details take a look at the 'Building Java & JVM projects' chapter in the Gradle
+ * User Manual available at https://docs.gradle.org/8.1.1/userguide/building_java_projects.html
+ */
+
+plugins {
+    // Apply the application plugin to add support for building a CLI application in Java.
+    id 'application'
+}
+
+repositories {
+    // Use Maven Central for resolving dependencies.
+    mavenCentral()
+}
+
+dependencies {
+    // Use JUnit Jupiter for testing.
+    testImplementation 'org.junit.jupiter:junit-jupiter:5.9.1'
+    testImplementation "org.assertj:assertj-core:3.11.1"
+
+    // This dependency is used by the application.
+    implementation 'com.google.guava:guava:31.1-jre'
+}
+
+// Apply a specific Java toolchain to ease working on different environments.
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(11)
+    }
+}
+
+application {
+    // Define the main class for the application.
+    mainClass = 'java.calculator.Main'
+}
+
+tasks.named('test') {
+    // Use JUnit Platform for unit tests.
+    useJUnitPlatform()
+}

app/src/main/java/Main.java

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+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+
+import calculator.Calculator;
+
+import java.io.IOException;
+
+public class Main {
+    public static void main(String[] args) throws IOException {
+        Calculator calculator = new Calculator();
+        calculator.run();
+    }
+}

app/src/main/java/Print/Choice.java

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+package Print;
+
+public class Choice {
+    public static void printChoice() {
+        System.out.println("0. 종료");
+        System.out.println("1. 조회");
+        System.out.println("2. 계산");
+
+        System.out.println();
+        System.out.print("선택: ");
+    }
+}

app/src/main/java/calculator/Calculator.java

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+package calculator;
+
+import function.Calculation;
+import function.Storage;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+
+import static Print.Choice.printChoice;
+import static validator.Validator.checkChoiceNum;
+
+public class Calculator {
+    public void run() throws IOException {
+        BufferedReader br;
+        Storage storage = new Storage();
+        Calculation calculation = new Calculation();
+
+        while (true) {
+            printChoice();
+
+            br = new BufferedReader(new InputStreamReader(System.in));
+            int choice = checkChoiceNum(Integer.parseInt(br.readLine()));
+            System.out.println();
+
+            if (choice == 0) {
+                break;
+            } else if (choice == 1) {
+                System.out.println(storage.print());
+            } else {
+                br = new BufferedReader(new InputStreamReader(System.in));
+                String expression = br.readLine();
+                String result = convertByType(calculation.calculatePostfix(calculation.convertPostfix(expression)));
+
+                storage.store(expression + " = " + result);
+                System.out.println(result);
+                System.out.println();
+            }
+        }
+    }
+
+    private String convertByType(double result) {
+        if (result == (int) result) {
+            return String.valueOf((int) result);
+        }
+        return String.valueOf(result);
+    }
+}

app/src/main/java/function/Calculation.java

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+package function;
+
+import operator.Operator;
+
+import java.util.Stack;
+
+import static validator.Validator.checkPositiveNum;
+import static validator.Validator.checkValidOperator;
+
+public class Calculation {
+    private static int priority(char operator) {
+        if (operator == '(' || operator == ')') {
+            return 0;
+        } else if (operator == '+' || operator == '-') {
+            return 1;
+        } else if (operator == '*' || operator == '/') {
+            return 2;
+        }
+        return -1;
+    }
+
+    public String convertPostfix(String expression) {
+        Stack<Character> stack = new Stack<>();
+        StringBuilder sb = new StringBuilder();
+
+        String[] split = expression.split(" ");
+
+        for (String now : split) {
+            if (checkPositiveNum(now)) {
+                sb.append(now).append(" ");
+                continue;
+            }
+
+            char c = checkValidOperator(now.charAt(0));
+
+            switch (c) {
+                case '(':
+                    stack.add(c);
+                    break;
+
+                case ')':
+                    while (!stack.isEmpty() && !(stack.peek() == '(')) {
+                        sb.append(stack.pop()).append(" ");
+                    }
+                    stack.pop();
+                    break;
+                default:
+                    while (!stack.isEmpty() && priority(stack.peek()) >= priority(c)) {
+                        sb.append(stack.pop()).append(" ");
+                    }
+                    stack.add(c);
+                    break;
+            }
+        }
+
+        while (!stack.isEmpty()) {
+            sb.append(stack.pop()).append(" ");
+        }
+
+        return sb.toString();
+    }
+
+    public double calculatePostfix(String postfix) {
+        String[] pfs = postfix.split(" ");
+        Stack<String> stack = new Stack<>();
+        Operator operator = new Operator();
+
+        for (String pf : pfs) {
+            if (checkPositiveNum(pf)) {
+                stack.add(pf);
+                continue;
+            }
+
+            char op = pf.charAt(0);
+            double numEnd = Double.parseDouble(stack.pop());
+            double numFront = Double.parseDouble(stack.pop());
+
+            String result = "";
+            switch (op) {
+                case '+':
+                    result = String.valueOf(operator.add(numFront, numEnd));
+                    break;
+                case '-':
+                    result = String.valueOf(operator.subtract(numFront, numEnd));
+                    break;
+                case '*':
+                    result = String.valueOf(operator.multiply(numFront, numEnd));
+                    break;
+                case '/':
+                    result = String.valueOf(operator.divide(numFront, numEnd));
+                    break;
+            }
+
+            stack.add(result);
+        }
+
+        return Double.parseDouble(stack.pop());
+    }
+}