membercodegen.java

Javassist是一个开源的分析、编辑和创建Java字节码的类库。是由东京技术学院的数学和计算机科学系的 Shigeru Chiba 所创建的。它已加入了开放源代码JBoss 应用服务器项目,通过使

            if (s == null)
                break;          // int[][][] a = new int[3][4][];

            ++count;
            s.accept(this);
            if (exprType != INT)
                throw new CompileError("bad type for array size");
        }

        String desc;
        exprType = type;
        arrayDim = dim;
        if (type == CLASS) {
            className = resolveClassName(classname);
            desc = toJvmArrayName(className, dim);
        }
        else
            desc = toJvmTypeName(type, dim);

        bytecode.addMultiNewarray(desc, count);
    }

    public void atCallExpr(CallExpr expr) throws CompileError {
        String mname = null;
        CtClass targetClass = null;
        ASTree method = expr.oprand1();
        ASTList args = (ASTList)expr.oprand2();
        boolean isStatic = false;
        boolean isSpecial = false;
        int aload0pos = -1;

        MemberResolver.Method cached = expr.getMethod();
        if (method instanceof Member) {
            mname = ((Member)method).get();
            targetClass = thisClass;
            if (inStaticMethod || (cached != null && cached.isStatic()))
                isStatic = true;            // should be static
            else {
                aload0pos = bytecode.currentPc();
                bytecode.addAload(0);       // this
            }
        }
        else if (method instanceof Keyword) {   // constructor
            isSpecial = true;
            mname = MethodInfo.nameInit;        // <init>
            targetClass = thisClass;
            if (inStaticMethod)
                throw new CompileError("a constructor cannot be static");
            else
                bytecode.addAload(0);   // this

            if (((Keyword)method).get() == SUPER)
                targetClass = MemberResolver.getSuperclass(targetClass);
        }
        else if (method instanceof Expr) {
            Expr e = (Expr)method;
            mname = ((Symbol)e.oprand2()).get();
            int op = e.getOperator();
            if (op == MEMBER) {                 // static method
                targetClass
                    = resolver.lookupClass(((Symbol)e.oprand1()).get(), false);
                isStatic = true;
            }
            else if (op == '.') {
                ASTree target = e.oprand1();
                if (target instanceof Keyword)
                    if (((Keyword)target).get() == SUPER)
                        isSpecial = true;

                try {
                    target.accept(this);
                }
                catch (NoFieldException nfe) {
                    if (nfe.getExpr() != target)
                        throw nfe;

                    // it should be a static method.
                    exprType = CLASS;
                    arrayDim = 0;
                    className = nfe.getField(); // JVM-internal
                    resolver.recordPackage(className);
                    isStatic = true;
                }

                if (arrayDim > 0)
                    targetClass = resolver.lookupClass(javaLangObject, true);
                else if (exprType == CLASS /* && arrayDim == 0 */)
                    targetClass = resolver.lookupClassByJvmName(className);
                else
                    badMethod();
            }
            else
                badMethod();
        }
        else
            fatal();

        atMethodCallCore(targetClass, mname, args, isStatic, isSpecial,
                         aload0pos, cached);
    }

    private static void badMethod() throws CompileError {
        throw new CompileError("bad method");
    }

    /*
     * atMethodCallCore() is also called by doit() in NewExpr.ProceedForNew
     *
     * @param targetClass       the class at which method lookup starts.
     * @param found         not null if the method look has been already done.
     */
    public void atMethodCallCore(CtClass targetClass, String mname,
                        ASTList args, boolean isStatic, boolean isSpecial,
                        int aload0pos, MemberResolver.Method found)
        throws CompileError
    {
        int nargs = getMethodArgsLength(args);
        int[] types = new int[nargs];
        int[] dims = new int[nargs];
        String[] cnames = new String[nargs];

        if (!isStatic && found != null && found.isStatic()) {
            bytecode.addOpcode(POP);
            isStatic = true;
        }

        int stack = bytecode.getStackDepth();

        // generate code for evaluating arguments.
        atMethodArgs(args, types, dims, cnames);

        // used by invokeinterface
        int count = bytecode.getStackDepth() - stack + 1;

        if (found == null)
            found = resolver.lookupMethod(targetClass, thisClass, thisMethod,
                                          mname, types, dims, cnames);

        if (found == null) {
            String msg;
            if (mname.equals(MethodInfo.nameInit))
                msg = "constructor not found";
            else
                msg = "Method " + mname + " not found in "
                    + targetClass.getName();

            throw new CompileError(msg);
        }

        atMethodCallCore2(targetClass, mname, isStatic, isSpecial,
                          aload0pos, count, found);
    }

    private void atMethodCallCore2(CtClass targetClass, String mname,
                                   boolean isStatic, boolean isSpecial,
                                   int aload0pos, int count,
                                   MemberResolver.Method found)
        throws CompileError
    {
        CtClass declClass = found.declaring;
        MethodInfo minfo = found.info;
        String desc = minfo.getDescriptor();
        int acc = minfo.getAccessFlags();

        if (mname.equals(MethodInfo.nameInit)) {
            isSpecial = true;
            if (declClass != targetClass)
                throw new CompileError("no such a constructor");

            if (declClass != thisClass && AccessFlag.isPrivate(acc)) {
                desc = getAccessibleConstructor(desc, declClass, minfo);
                bytecode.addOpcode(Opcode.ACONST_NULL); // the last parameter
            }
        }
        else if (AccessFlag.isPrivate(acc))
            if (declClass == thisClass)
                isSpecial = true;
            else {
                isSpecial = false;
                isStatic = true;
                String origDesc = desc;
                if ((acc & AccessFlag.STATIC) == 0)
                    desc = Descriptor.insertParameter(declClass.getName(),
                                                      origDesc);

                acc = AccessFlag.setPackage(acc) | AccessFlag.STATIC;
                mname = getAccessiblePrivate(mname, origDesc, desc,
                                             minfo, declClass);
            }

        boolean popTarget = false;
        if ((acc & AccessFlag.STATIC) != 0) {
            if (!isStatic) {
                /* this method is static but the target object is
                   on stack.  It must be popped out.  If aload0pos >= 0,
                   then the target object was pushed by aload_0.  It is
                   overwritten by NOP.
                */
                isStatic = true;
                if (aload0pos >= 0)
                    bytecode.write(aload0pos, NOP);
                else
                    popTarget = true;
            }

            bytecode.addInvokestatic(declClass, mname, desc);
        }
        else if (isSpecial)    // if (isSpecial && notStatic(acc))
            bytecode.addInvokespecial(declClass, mname, desc);
        else if (declClass.isInterface())
            bytecode.addInvokeinterface(declClass, mname, desc, count);
        else
            if (isStatic)
                throw new CompileError(mname + " is not static");
            else
                bytecode.addInvokevirtual(declClass, mname, desc);

        setReturnType(desc, isStatic, popTarget);
    }

    /*
     * Finds (or adds if necessary) a hidden accessor if the method
     * is in an enclosing class.
     *
     * @param desc          the descriptor of the method.
     * @param declClass     the class declaring the method.
     */
    protected String getAccessiblePrivate(String methodName, String desc,
                                          String newDesc, MethodInfo minfo,
                                          CtClass declClass)
        throws CompileError
    {
        if (isEnclosing(declClass, thisClass)) {
            AccessorMaker maker = declClass.getAccessorMaker();
            if (maker != null)
                return maker.getMethodAccessor(methodName, desc, newDesc,
                                               minfo);
        }

        throw new CompileError("Method " + methodName
                               + " is private");
    }

    /*
     * Finds (or adds if necessary) a hidden constructor if the given
     * constructor is in an enclosing class.
     *
     * @param desc          the descriptor of the constructor.
     * @param declClass     the class declaring the constructor.
     * @param minfo         the method info of the constructor.
     * @return the descriptor of the hidden constructor.
     */
    protected String getAccessibleConstructor(String desc, CtClass declClass,
                                              MethodInfo minfo)
        throws CompileError
    {
        if (isEnclosing(declClass, thisClass)) {
            AccessorMaker maker = declClass.getAccessorMaker();
            if (maker != null)
                return maker.getConstructor(declClass, desc, minfo);
        }

        throw new CompileError("the called constructor is private in "
                               + declClass.getName());
    }

    private boolean isEnclosing(CtClass outer, CtClass inner) {
        try {
            while (inner != null) {
                inner = inner.getDeclaringClass();
                if (inner == outer)
                    return true;
            }
        }
        catch (NotFoundException e) {}
        return false;   
    }

    public int getMethodArgsLength(ASTList args) {
        return ASTList.length(args);
    }

    public void atMethodArgs(ASTList args, int[] types, int[] dims,
                             String[] cnames) throws CompileError {
        int i = 0;
        while (args != null) {
            ASTree a = args.head();
            a.accept(this);
            types[i] = exprType;
            dims[i] = arrayDim;
            cnames[i] = className;
            ++i;
            args = args.tail();
        }
    }

    void setReturnType(String desc, boolean isStatic, boolean popTarget)
        throws CompileError
    {
        int i = desc.indexOf(')');
        if (i < 0)
            badMethod();

        char c = desc.charAt(++i);
        int dim = 0;
        while (c == '[') {
            ++dim;
            c = desc.charAt(++i);
        }

        arrayDim = dim;
        if (c == 'L') {
            int j = desc.indexOf(';', i + 1);
            if (j < 0)
                badMethod();

            exprType = CLASS;
            className = desc.substring(i + 1, j);
        }
        else {
            exprType = MemberResolver.descToType(c);
            className = null;
        }

        int etype = exprType;
        if (isStatic) {
            if (popTarget) {
                if (is2word(etype, dim)) {
                    bytecode.addOpcode(DUP2_X1);
                    bytecode.addOpcode(POP2);
                    bytecode.addOpcode(POP);
                }
                else if (etype == VOID)
                    bytecode.addOpcode(POP);
                else {
                    bytecode.addOpcode(SWAP);
                    bytecode.addOpcode(POP);
                }
            }
        }
    }

    protected void atFieldAssign(Expr expr, int op, ASTree left,
                        ASTree right, boolean doDup) throws CompileError
    {
        CtField f = fieldAccess(left, false);
        boolean is_static = resultStatic;
        if (op != '=' && !is_static)
            bytecode.addOpcode(DUP);

        int fi;
        if (op == '=') {
            FieldInfo finfo = f.getFieldInfo2();
            setFieldType(finfo);
            AccessorMaker maker = isAccessibleField(f, finfo);            
            if (maker == null)