!7

set flag AllPublic.

!include once #1019934 // BCEL

import org.apache.bcel.Const;

import org.apache.bcel.generic.*;

replace BType with org.apache.bcel.generic.Type.

p {

  ClassGen cg = new("User123", "java.lang.Object", null,

    Const.ACC_PUBLIC, new S[] { className(IF0) });

  cg.addEmptyConstructor(Const.ACC_PUBLIC);

  // make code for get() method

  new InstructionList il;

  ConstantPoolGen cp = cg.getConstantPool();

  var factory = new InstructionFactory(cg);

  var mg = new MethodGen(Const.ACC_PUBLIC,

    new ObjectType(className(/*S*/O)), // String doesn't work

    new BType[] {}, null, "get", cg.getClassName(), il, cp);

  // create empty StringBuffer, store in local variable

  int iBuffer = 1; // local variable index

  il.append(factory.createNew("java.lang.StringBuffer"));

  il.append(InstructionConst.DUP);

  il.append(factory.createInvoke("java.lang.StringBuffer", "<init>", BType.VOID, new BType[] {}, Const.INVOKESPECIAL));

  il.append(new ASTORE(iBuffer));

  // Append twice

  for (string : ll("Hello ", "world")) {

    il.append(new ALOAD(iBuffer));

    il.append(new PUSH(cp, string));

    il.append(factory.createAppend(org.apache.bcel.generic.Type.OBJECT));

  }

  // call StringBuffer.toString() and return

  il.append(new ALOAD(iBuffer));

  il.append(factory.createInvoke("java.lang.StringBuffer", "toString",

    new ObjectType("java.lang.String"), new BType[] {}, Const.INVOKEVIRTUAL));

  il.append(InstructionConst.ARETURN);

  mg.stripAttributes(true);

  mg.setMaxStack();

  mg.setMaxLocals();

  cg.addMethod(mg.getMethod());

  // bake class

  JavaClass baked = cg.getJavaClass();

  // print class overview

  print(baked);

  // print the methods

  for (method : baked.getMethods()) {

    print("\n" + method);

    print(method.getCode());

  }

  byte[] bytes = baked.getBytes();

  var cl = new InMemoryClassLoader(myClassLoader());

  time "Defining class" {

    Class<? extends IF0> c = cast cl.defineAClass("User123", bytes);

  }

  print(c);

  IF0 f = newInstance(c);

  print(f);

  assertEqualsVerbose("Hello world", f!);

}