simple cmd implementation

Author: a5right

Diff for: .gitattributes

@@ -0,0 +1,9 @@
+#
+# 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
+

Diff for: .gitignore

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+# Ignore Gradle project-specific cache directory
+.gradle
+.idea
+
+# Ignore Gradle build output directory
+build
+app/bin

Diff for: 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/8.0.2/userguide/building_java_projects.html
+ */
+
+plugins {
+    // Apply the application plugin to add support for building a CLI application in Java.
+    id 'application'
+    id 'java'
+}
+
+
+sourceCompatibility = "1.8";
+
+
+repositories {
+    // Use Maven Central for resolving dependencies.
+    mavenCentral()
+}
+
+dependencies {
+    // Use JUnit Jupiter for testing.
+    testImplementation 'org.junit.jupiter:junit-jupiter:5.9.1'
+
+    // This dependency is used by the application.
+//    implementation 'com.google.guava:guava:31.1-jre'
+
+    implementation 'commons-cli:commons-cli:1.4'
+}
+
+application {
+    // Define the main class for the application.
+    mainClass = 'write.your.own.jvm.App'
+}
+
+tasks.named('test') {
+    // Use JUnit Platform for unit tests.
+    useJUnitPlatform()
+}
+
+if (hasProperty('buildScan')) {
+    buildScan {
+        termsOfServiceUrl = 'https://gradle.com/terms-of-service'
+        termsOfServiceAgree = 'yes'
+    }
+}

Diff for: app/src/main/java/write/your/own/jvm/Cmd.java

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+package write.your.own.jvm;
+
+
+import org.apache.commons.cli.*;
+
+import java.util.Arrays;
+import java.util.List;
+
+
+public class Cmd {
+    private final String classpath;
+    private final String mainClass;
+    private final List<String> args;
+
+    public Cmd(String classpath, String mainClass, List<String> args) {
+        this.classpath = classpath;
+        this.mainClass = mainClass;
+        this.args = args;
+    }
+
+    public static Cmd parseArgs(String[] args) {
+        // create Options object
+        Options options = new Options();
+        // add option
+        options.addOption("h", false, "print help message");
+        options.addOption("v", false, "print version");
+        // -cp equals -classpath
+        options.addOption("cp", true, "class path where to find");
+
+        try {
+            // Create a parser
+            CommandLineParser parser = new DefaultParser();
+            // parse the options passed as command line arguments
+            CommandLine commandLine = parser.parse(options, args);
+            if (commandLine.hasOption("h")) {
+                printHelp();
+                System.exit(0);
+            }
+
+            if (commandLine.hasOption("v")) {
+                printVersion();
+            }
+
+            if (commandLine.hasOption("cp")) {
+                printClasspath(commandLine.getOptionValue("cp"));
+            }
+            String cp = commandLine.getOptionValue("cp");
+            String[] leftArgs = commandLine.getArgs();
+            return new Cmd(cp, leftArgs[0], Arrays.asList(leftArgs).subList(1, leftArgs.length));
+        } catch (ParseException e) {
+            e.printStackTrace();
+            printHelp();
+        }
+        return null;
+    }
+
+    private static void printClasspath(String classpath) {
+        Log.d("classpath: " + classpath);
+    }
+
+    private static void printVersion() {
+        Log.d("version: 0.1.0");
+    }
+
+    private static void printHelp() {
+        Log.d("usage: <mc> [args] [-options]");
+        Log.d("mc: main class name");
+        Log.d("args: main class args");
+        Log.d(" -h      usage help");
+        Log.d(" -v      current version");
+        Log.d(" -cp     class path which need to load");
+    }
+
+    public String getClasspath() {
+        return classpath;
+    }
+
+    public String getMainClass() {
+        return mainClass;
+    }
+
+    public List<String> getArgs() {
+        return args;
+    }
+}

Diff for: app/src/main/java/write/your/own/jvm/Log.java

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+package write.your.own.jvm;
+
+public class Log {
+    public static void d(String message) {
+        System.out.println(message);
+    }
+
+}

Diff for: app/src/main/java/write/your/own/jvm/Main.java

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+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+package write.your.own.jvm;
+
+public class Main {
+    public static void main(String[] args) {
+        Cmd cmd = Cmd.parseArgs(args);
+        printArgs(cmd);
+    }
+
+    private static void printArgs(Cmd cmd) {
+        Log.d("classpath: " + cmd.getClasspath());
+        Log.d("main class: " + cmd.getMainClass());
+        Log.d("args: " + cmd.getArgs().toString());
+    }
+}

Diff for: app/src/test/java/write/your/own/jvm/MainTest.java

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+/*
+ * This Java source file was generated by the Gradle 'init' task.
+ */
+package write.your.own.jvm;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+class MainTest {
+    @Test void appHasAGreeting() {
+//        App classUnderTest = new App();
+//        assertNotNull(classUnderTest.getGreeting(), "app should have a greeting");
+    }
+}

Diff for: gradle/wrapper/gradle-wrapper.jar

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+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.0.2-bin.zip
+networkTimeout=10000
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists