Hw 11

pom.xml

@@ -45,6 +45,8 @@
 
         <jacoco-maven-plugin.version>0.8.10</jacoco-maven-plugin.version>
         <kotlin.version>1.9.20</kotlin.version>
+            <bytebuddy.version>1.14.8</bytebuddy.version>
+            <asm.version>9.6</asm.version>
         <jmh.version>1.37</jmh.version>
     </properties>
 
@@ -114,6 +116,22 @@
             <version>3.2.0</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.ow2.asm</groupId>
+            <artifactId>asm</artifactId>
+            <version>${asm.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>net.bytebuddy</groupId>
+            <artifactId>byte-buddy-agent</artifactId>
+            <version>${bytebuddy.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>net.bytebuddy</groupId>
+            <artifactId>byte-buddy</artifactId>
+            <version>${bytebuddy.version}</version>
+        </dependency>
         <!-- JMH -->
         <dependency>
             <groupId>org.openjdk.jmh</groupId>

src/main/java/edu/hw_11/ArithmeticUtils.java

@@ -0,0 +1,11 @@
+package edu.hw_11;
+
+public class ArithmeticUtils {
+
+    private ArithmeticUtils() {
+    }
+
+    public static int sum(int a, int b) {
+        return a + b;
+    }
+}

src/main/java/edu/hw_11/Multiplier.java

@@ -0,0 +1,11 @@
+package edu.hw_11;
+
+public class Multiplier {
+
+    private Multiplier() {
+    }
+
+    public static int multiply(int a, int b) {
+        return a * b;
+    }
+}

src/main/java/edu/hw_11/task3/Fib.java

@@ -0,0 +1,18 @@
+package edu.hw_11.task3;
+
+public class Fib {
+
+    private Fib() {
+    }
+
+    public static long fib(int n) {
+        long last = 0;
+        long next = 1;
+        for (int i = 0; i < n; i++) {
+            long oldLast = last;
+            last = next;
+            next = oldLast + next;
+        }
+        return last;
+    }
+}

src/main/java/edu/hw_11/task3/FibImplementation.java

@@ -0,0 +1,20 @@
+package edu.hw_11.task3;
+
+import net.bytebuddy.dynamic.scaffold.InstrumentedType;
+import net.bytebuddy.implementation.Implementation;
+import net.bytebuddy.implementation.bytecode.ByteCodeAppender;
+import org.jetbrains.annotations.NotNull;
+
+public enum FibImplementation implements Implementation {
+    INSTANCE;
+
+    @Override
+    public @NotNull ByteCodeAppender appender(@NotNull Target target) {
+        return FibMethod.INSTANCE;
+    }
+
+    @Override
+    public @NotNull InstrumentedType prepare(@NotNull InstrumentedType instrumentedType) {
+        return instrumentedType;
+    }
+}

src/main/java/edu/hw_11/task3/FibMethod.java

@@ -0,0 +1,31 @@
+package edu.hw_11.task3;
+
+import net.bytebuddy.description.method.MethodDescription;
+import net.bytebuddy.implementation.Implementation;
+import net.bytebuddy.implementation.bytecode.ByteCodeAppender;
+import net.bytebuddy.implementation.bytecode.StackManipulation;
+import net.bytebuddy.jar.asm.MethodVisitor;
+import org.jetbrains.annotations.NotNull;
+
+public enum FibMethod implements ByteCodeAppender {
+    INSTANCE;
+
+    @Override
+    public @NotNull Size apply(
+        @NotNull MethodVisitor mv,
+        Implementation.@NotNull Context implementationContext,
+        MethodDescription instrumentedMethod
+    ) {
+        if (!instrumentedMethod.getReturnType().asErasure().represents(long.class)) {
+            throw new IllegalArgumentException(instrumentedMethod + " must return long");
+        }
+        StackManipulation.Size operandStackSize = new StackManipulation.Compound(
+            FibNumber.INSTANCE
+        ).apply(mv, implementationContext);
+        return new Size(
+            operandStackSize.getMaximalSize(),
+            instrumentedMethod.getStackSize()
+        );
+    }
+}
+

src/main/java/edu/hw_11/task3/FibNumber.java

@@ -0,0 +1,55 @@
+package edu.hw_11.task3;
+
+import net.bytebuddy.implementation.Implementation;
+import net.bytebuddy.implementation.bytecode.StackManipulation;
+import net.bytebuddy.jar.asm.Label;
+import net.bytebuddy.jar.asm.MethodVisitor;
+import net.bytebuddy.jar.asm.Opcodes;
+import org.jetbrains.annotations.NotNull;
+
+@SuppressWarnings("MagicNumber")
+enum FibNumber implements StackManipulation {
+
+    INSTANCE; // singleton
+
+    @Override
+    public boolean isValid() {
+        return true;
+    }
+
+    @SuppressWarnings({"LineLength", "MultipleStringLiterals"})
+    @Override
+    public @NotNull Size apply(
+        MethodVisitor methodVisitor,
+        Implementation.@NotNull Context implementationContext
+    ) {
+        methodVisitor.visitCode();
+        // if (n <= 1)
+        Label l1 = new Label();
+        methodVisitor.visitVarInsn(Opcodes.ILOAD, 0);
+        methodVisitor.visitInsn(Opcodes.ICONST_1);
+        methodVisitor.visitJumpInsn(Opcodes.IF_ICMPGT, l1);
+        // return n
+        methodVisitor.visitVarInsn(Opcodes.ILOAD, 0);
+        methodVisitor.visitInsn(Opcodes.I2L);
+        methodVisitor.visitInsn(Opcodes.LRETURN);
+        // if (n > 1)
+        methodVisitor.visitLabel(l1);
+        methodVisitor.visitFrame(Opcodes.F_SAME, 0, null, 0, null);
+        // fib(n - 1)
+        methodVisitor.visitVarInsn(Opcodes.ILOAD, 0);
+        methodVisitor.visitInsn(Opcodes.ICONST_1);
+        methodVisitor.visitInsn(Opcodes.ISUB);
+        methodVisitor.visitMethodInsn(Opcodes.INVOKESTATIC, "edu/hw_11/FibExample", "fib", "(I)J", false);
+        // fib(n - 2)
+        methodVisitor.visitVarInsn(Opcodes.ILOAD, 0);
+        methodVisitor.visitInsn(Opcodes.ICONST_2);
+        methodVisitor.visitInsn(Opcodes.ISUB);
+        methodVisitor.visitMethodInsn(Opcodes.INVOKESTATIC, "edu/hw_11/FibExample", "fib", "(I)J", false);
+        // fib(n - 1) + fib(n - 2);
+        methodVisitor.visitInsn(Opcodes.LADD);
+        methodVisitor.visitInsn(Opcodes.LRETURN);
+        methodVisitor.visitEnd();
+        return new Size(-1, 4);
+    }
+}

src/test/java/edu/hw_11/FibExample.java

@@ -0,0 +1,19 @@
+package edu.hw_11;
+
+public class FibExample {
+    private FibExample() {
+    }
+
+    @SuppressWarnings("MagicNumber")
+    public static long fib(int n) {
+        long last = 10;
+        long next = 111;
+        for (int i = 0; i < n; i++) {
+            long oldLast = last;
+            last = next;
+            next = oldLast - next;
+        }
+        return last;
+    }
+
+}

src/test/java/edu/hw_11/Task1Test.java

@@ -0,0 +1,27 @@
+package edu.hw_11;
+
+import java.lang.reflect.InvocationTargetException;
+import net.bytebuddy.ByteBuddy;
+import net.bytebuddy.implementation.FixedValue;
+import org.junit.jupiter.api.Test;
+import static net.bytebuddy.matcher.ElementMatchers.named;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+public class Task1Test {
+    @Test
+    void generateClassThatPrintsHello()
+        throws NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException {
+        String hello = new ByteBuddy()
+            .subclass(Object.class)
+            .name("example.Type")
+            .method(named("toString")).intercept(FixedValue.value("Hello ByteBuddy!"))
+            .make()
+            .load(getClass().getClassLoader())
+            .getLoaded()
+            .getConstructor()
+            .newInstance()
+            .toString();
+
+        assertThat(hello).isEqualTo("Hello ByteBuddy!");
+    }
+}

src/test/java/edu/hw_11/Task2Test.java

@@ -0,0 +1,32 @@
+package edu.hw_11;
+
+import net.bytebuddy.ByteBuddy;
+import net.bytebuddy.description.type.TypeDescription;
+import net.bytebuddy.dynamic.ClassFileLocator;
+import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
+import net.bytebuddy.implementation.MethodDelegation;
+import net.bytebuddy.jar.asm.Opcodes;
+import net.bytebuddy.pool.TypePool;
+import org.junit.jupiter.api.Test;
+import java.lang.reflect.InvocationTargetException;
+import static net.bytebuddy.matcher.ElementMatchers.named;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+public class Task2Test {
+    @Test
+    void multipliesInsteadOfAdding() {
+        TypeDescription typeDescription = TypePool.Default.ofSystemLoader()
+            .describe("edu.hw_11.ArithmeticUtils")
+            .resolve();
+        new ByteBuddy()
+            .redefine(typeDescription, ClassFileLocator.ForClassLoader.ofSystemLoader())
+            .method(named("sum")).intercept(MethodDelegation.to(Multiplier.class))
+            .make()
+            .load(ClassLoader.getSystemClassLoader(), ClassLoadingStrategy.Default.INJECTION);
+
+        int result = ArithmeticUtils
+            .sum(1, 2);
+
+        assertThat(result).isEqualTo(2);
+    }
+}

src/test/java/edu/hw_11/Task3Test.java

@@ -0,0 +1,30 @@
+package edu.hw_11;
+
+import edu.hw_11.task3.FibImplementation;
+import net.bytebuddy.ByteBuddy;
+import net.bytebuddy.description.type.TypeDescription;
+import net.bytebuddy.dynamic.ClassFileLocator;
+import net.bytebuddy.dynamic.loading.ClassLoadingStrategy;
+import net.bytebuddy.pool.TypePool;
+import org.junit.jupiter.api.Test;
+import static net.bytebuddy.matcher.ElementMatchers.named;
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+
+public class Task3Test {
+    @Test
+    void countsFibGenerated() {
+        TypeDescription typeDescription = TypePool.Default.ofSystemLoader()
+            .describe("edu.hw_11.FibExample")
+            .resolve();
+
+
+        new ByteBuddy()
+            .redefine(typeDescription, ClassFileLocator.ForClassLoader.ofSystemLoader())
+            .method(named("fib")).intercept(FibImplementation.INSTANCE)
+            .make()
+            .load(ClassLoader.getSystemClassLoader(), ClassLoadingStrategy.Default.INJECTION);
+
+            assertThat(FibExample.fib(6)).isEqualTo(8L);
+
+    }
+}