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spullaraspullara
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compile the class guard
1 parent 39f4096 commit a0230a2

4 files changed

Lines changed: 170 additions & 3 deletions

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‎compiler/pom.xml‎

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@@ -53,6 +53,18 @@
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<version>12.0</version>
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</dependency>
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<!-- ASM -->
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<dependency>
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<groupId>org.ow2.asm</groupId>
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<artifactId>asm-commons</artifactId>
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<version>4.0</version>
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</dependency>
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<dependency>
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<groupId>org.ow2.asm</groupId>
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<artifactId>asm-util</artifactId>
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<version>4.0</version>
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</dependency>
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<!-- Scala -->
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<dependency>
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<groupId>org.scala-lang</groupId>

‎compiler/src/main/java/com/github/mustachejava/reflect/ClassGuard.java‎

Lines changed: 59 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,12 @@
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package com.github.mustachejava.reflect;
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import com.google.common.base.Predicate;
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import org.objectweb.asm.ClassWriter;
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import org.objectweb.asm.Label;
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import org.objectweb.asm.Type;
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import org.objectweb.asm.commons.GeneratorAdapter;
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import org.objectweb.asm.commons.Method;
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import static org.objectweb.asm.commons.GeneratorAdapter.*;
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/**
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* Ensure that the class of the current scope is that same as when this wrapper was generated.
@@ -9,7 +15,7 @@
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* Time: 9:23 AM
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* To change this template use File | Settings | File Templates.
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*/
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public class ClassGuard implements Predicate<Object[]> {
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public class ClassGuard implements Guard {
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private final Class classGuard;
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private final int scopeIndex;
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@@ -33,6 +39,56 @@ public boolean equals(Object o) {
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public boolean apply(Object[] scopes) {
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if (scopes == null || scopes.length <= scopeIndex) return false;
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Object scope = scopes[scopeIndex];
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return (scope == null && classGuard == null) || (scope != null && classGuard == scope.getClass());
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if (scope != null && classGuard != scope.getClass()) return false;
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if (scope == null && classGuard != null) return false;
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return true;
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}
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@Override
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public void addGuard(Label returnFalse, GeneratorAdapter gm, GeneratorAdapter sm, ClassWriter cw, int id, String className) {
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// Add the field for the class guard
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cw.visitField(ACC_PUBLIC | ACC_STATIC, "classGuard" + id, "Ljava/lang/Class;", null, null);
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// Initialize the field
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sm.push(classGuard.getName());
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sm.invokeStatic(Type.getType(Class.class), Method.getMethod("Class forName(String)"));
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sm.putStatic(Type.getType(className), "classGuard" + id, Type.getType(Class.class));
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Label next = new Label();
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Label scopeIsNull = new Label();
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gm.loadArg(0); // scopes
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gm.ifNull(returnFalse); // if scopes == null return false
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gm.loadArg(0); // scopes
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gm.arrayLength(); // scopes.length
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gm.push(scopeIndex);
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gm.ifICmp(LE, returnFalse); // scopes.length <= scopeIndex return false
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gm.loadArg(0); // scopes
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gm.push(scopeIndex);
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gm.arrayLoad(Type.getType(Object.class)); // Object[]
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int scopeLocal = gm.newLocal(Type.getType(Object.class));
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gm.storeLocal(scopeLocal);
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int classGuardLocal = gm.newLocal(Type.getType(Class.class));
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gm.getStatic(Type.getType(className), "classGuard" + id, Type.getType(Class.class));
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gm.storeLocal(classGuardLocal);
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gm.loadLocal(scopeLocal);
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gm.ifNull(scopeIsNull); // after here scope is not null
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gm.loadLocal(scopeLocal);
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gm.invokeVirtual(Type.getType(Object.class), Method.getMethod("Class getClass()")); // scope.getClass()
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gm.loadLocal(classGuardLocal);
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gm.ifCmp(Type.getType(Class.class), NE, returnFalse); // if they are not equal return false
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gm.goTo(next); // next guard
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gm.visitLabel(scopeIsNull); // after here scope is null
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gm.loadLocal(classGuardLocal);
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gm.ifNonNull(returnFalse); // if there is a class guard, return false
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gm.visitLabel(next); // end of method
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}
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}

‎compiler/src/main/java/com/github/mustachejava/reflect/Guard.java‎

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Original file line numberDiff line numberDiff line change
@@ -0,0 +1,14 @@
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package com.github.mustachejava.reflect;
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import com.google.common.base.Predicate;
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import org.objectweb.asm.ClassWriter;
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import org.objectweb.asm.Label;
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import org.objectweb.asm.Opcodes;
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import org.objectweb.asm.commons.GeneratorAdapter;
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/**
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* Optimize guards
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*/
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public interface Guard extends Predicate<Object[]>, Opcodes {
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void addGuard(Label returnFalse, GeneratorAdapter gm, GeneratorAdapter cm, ClassWriter cw, int id, String className);
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}

‎compiler/src/test/java/com/github/mustachejava/reflect/CompiledGuard.java‎

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Original file line numberDiff line numberDiff line change
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package com.github.mustachejava.reflect;
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import org.junit.Test;
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import org.objectweb.asm.ClassWriter;
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import org.objectweb.asm.Label;
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import org.objectweb.asm.Opcodes;
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import org.objectweb.asm.Type;
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import org.objectweb.asm.commons.GeneratorAdapter;
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import java.lang.reflect.InvocationTargetException;
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import static junit.framework.Assert.assertFalse;
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import static junit.framework.Assert.assertTrue;
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import static org.objectweb.asm.commons.Method.getMethod;
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/**
17+
* Test our guard compilations
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*/
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public class CompiledGuard implements Opcodes {
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@Test
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public void testGuard() {
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ClassGuard stringClassGuard = new ClassGuard(0, "");
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assertTrue("string is ok", stringClassGuard.apply(new Object[]{"test"}));
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assertFalse("integer is not ok", stringClassGuard.apply(new Object[]{1}));
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}
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public interface TestGuard {
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boolean test(Object[] scopes);
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}
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@Test
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public void testCompiledGuard() throws NoSuchMethodException, InvocationTargetException, IllegalAccessException, InstantiationException {
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ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
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String className = "Test";
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cw.visit(V1_6, ACC_PUBLIC + ACC_SUPER, className, null, "java/lang/Object", new String[]{TestGuard.class.getName().replace(".", "/")});
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cw.visitSource("Test.java", null);
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GeneratorAdapter cm = new GeneratorAdapter(ACC_PUBLIC, getMethod("void <init> ()"), null, null, cw);
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cm.loadThis();
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cm.invokeConstructor(Type.getType(Object.class), getMethod("void <init> ()"));
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cm.returnValue();
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cm.endMethod();
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GeneratorAdapter sm = new GeneratorAdapter(ACC_PUBLIC | ACC_STATIC, getMethod("void <clinit> ()"), null, null, cw);
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{
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GeneratorAdapter gm = new GeneratorAdapter(ACC_PUBLIC, getMethod("boolean test(Object[])"), null, null, cw);
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Label returnFalse = new Label();
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ClassGuard stringClassGuard = new ClassGuard(0, "");
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stringClassGuard.addGuard(returnFalse, gm, sm, cw, 0, className);
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// Makes it through the guard, success
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gm.push(true);
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gm.returnValue();
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// Jumps to returnFalse, failure
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gm.visitLabel(returnFalse);
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gm.push(false);
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gm.returnValue();
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gm.endMethod();
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}
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sm.returnValue();
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sm.endMethod();
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cw.visitEnd();
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Class<?> aClass = defineClass(className, cw.toByteArray());
68+
TestGuard testGuard = (TestGuard) aClass.getConstructor().newInstance();
69+
assertTrue("string is ok", testGuard.test(new Object[]{"test"}));
70+
assertFalse("integer is not ok", testGuard.test(new Object[]{1}));
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}
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private static final DefiningClassLoader cl = new DefiningClassLoader();
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75+
private static class DefiningClassLoader extends ClassLoader {
76+
public Class<?> defineClass(final String name, final byte[] b) {
77+
return defineClass(name, b, 0, b.length);
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}
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}
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81+
public static Class<?> defineClass(String name, byte[] b) {
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return cl.defineClass(name, b);
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}
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}

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