!include once #1019934 // BCEL

sclass MethodMaker {
  replace Type with org.apache.bcel.generic.Type.
  
  ClassGen cg;
  MethodGen mg;
  new InstructionList il;
  ConstantPoolGen cp;
  InstructionFactory factory;
  int frameSize;
  
  *(ClassGen *cg, S methodName, Class returnType, Class... argumentTypes) {
    cp = cg.getConstantPool();
    factory = new InstructionFactory(cg);
  
    Type[] argTypes = wrapTypes(argumentTypes);
      
    mg = new MethodGen(Const.ACC_PUBLIC,
      new ObjectType(returnType),
      argTypes, null /* argNames */, methodName, cg.getClassName(), il, cp);
      
    frameSize = l(argTypes)+1; // assume method is not static
  }

  Type[] wrapTypes(Class[] classes) {  
    Type[] types = new[l(classes)];
    for i over classes:
      types[i] = wrapType(classes[i]);
  }
  
  Type wrapType(Class c) {
    ret c == null ?: new ObjectType(className(c));
  }

  // create local variable and return its index
  int newLocalVar() { ret ++frameSize; }
  
  selfType newObject(Class c, Class... argTypes) {
    il.append(factory.createNew(className(c)));
    il.append(InstructionConst.DUP);
    Constructor ctor = findConstructor_onTypes(c, argTypes);
    il.append(factory.createInvoke(className(c), "<init>",
      Type.VOID, wrapTypes(ctor.getParameterTypes()),
      Const.INVOKESPECIAL));
    this;
  }
  
  // store object in local variable
  selfType astore(int var) {
    il.append(new ASTORE(var));
    this;
  }

  selfType aload(int var) {  
    il.append(new ALOAD(var));
    this;
  }
  
  selfType stringConstant(S s) {
    il.append(new PUSH(cp, s));
    this;
  }
  
  selfType invokeVirtual(Class c, S methodName, Class returnType,
    Class... argTypes) {
    Method m = findMethod_onTypes(argTypes);
    il.append(factory.createInvoke(className(c), methodName,
      wrapType(m.getReturnType()),
      wrapTypes(m.getArgumentTypes()), Const.INVOKEVIRTUAL));
    this;
  }
  
  selfType areturn() {
    il.append(InstructionConst.ARETURN);
    this;
  }

  void done() {
    mg.stripAttributes(true);
    mg.setMaxStack();
    mg.setMaxLocals();
    cg.addMethod(mg.getMethod());
  }
}