parser.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

       Either "(int.class)" or "(String[].class)" is a not cast expression.
     */
    private ASTree parseCast(SymbolTable tbl) throws CompileError {
        int t = lex.lookAhead(1);
        if (isBuiltinType(t) && nextIsBuiltinCast()) {
            lex.get();  // '('
            lex.get();  // primitive type
            int dim = parseArrayDimension();
            if (lex.get() != ')')
                throw new CompileError(") is missing", lex);

            return new CastExpr(t, dim, parseUnaryExpr(tbl));
        }
        else if (t == Identifier && nextIsClassCast()) {
            lex.get();  // '('
            ASTList name = parseClassType(tbl);
            int dim = parseArrayDimension();
            if (lex.get() != ')')
                throw new CompileError(") is missing", lex);

            return new CastExpr(name, dim, parseUnaryExpr(tbl));
        }
        else
            return parsePostfix(tbl);
    }

    private boolean nextIsBuiltinCast() {
        int t;
        int i = 2;
        while ((t = lex.lookAhead(i++)) == '[')
            if (lex.lookAhead(i++) != ']')
                return false;

        return lex.lookAhead(i - 1) == ')';
    }

    private boolean nextIsClassCast() {
        int i = nextIsClassType(1);
        if (i < 0)
            return false;

        int t = lex.lookAhead(i);
        if (t != ')')
            return false;

        t = lex.lookAhead(i + 1);
        return t == '(' || t == NULL || t == StringL
               || t == Identifier || t == THIS || t == SUPER || t == NEW
               || t == TRUE || t == FALSE || t == LongConstant
               || t == IntConstant || t == CharConstant
               || t == DoubleConstant || t == FloatConstant;
    }

    private int nextIsClassType(int i) {
        int t;
        while (lex.lookAhead(++i) == '.')
            if (lex.lookAhead(++i) != Identifier)
                return -1;

        while ((t = lex.lookAhead(i++)) == '[')
            if (lex.lookAhead(i++) != ']')
                return -1;

        return i - 1;
    }

    /* array.dimension : [ "[" "]" ]*
     */
    private int parseArrayDimension() throws CompileError {
        int arrayDim = 0;
        while (lex.lookAhead() == '[') {
            ++arrayDim;
            lex.get();
            if (lex.get() != ']')
                throw new CompileError("] is missing", lex);
        }

        return arrayDim;
    }

    /* class.type : Identifier ( "." Identifier )*
     */
    private ASTList parseClassType(SymbolTable tbl) throws CompileError {
        ASTList list = null;
        for (;;) {
            if (lex.get() != Identifier)
                throw new SyntaxError(lex);

            list = ASTList.append(list, new Symbol(lex.getString()));
            if (lex.lookAhead() == '.')
                lex.get();
            else
                break;
        }

        return list;
    }

    /* postfix.expr : number.literal
     *              | primary.expr
     *              | method.expr
     *              | postfix.expr "++" | "--"
     *              | postfix.expr "[" array.size "]"
     *              | postfix.expr "." Identifier
     *              | postfix.expr ( "[" "]" )* "." CLASS
     *              | postfix.expr "#" Identifier
     *
     * "#" is not an operator of regular Java.  It separates
     * a class name and a member name in an expression for static member
     * access.  For example,
     *     java.lang.Integer.toString(3)        in regular Java
     * can be written like this:
     *     java.lang.Integer#toString(3)        for this compiler.
     */
    private ASTree parsePostfix(SymbolTable tbl) throws CompileError {
        int token = lex.lookAhead();
        switch (token) {    // see also parseUnaryExpr()
        case LongConstant :
        case IntConstant :
        case CharConstant :
            lex.get();
            return new IntConst(lex.getLong(), token);
        case DoubleConstant :
        case FloatConstant :
            lex.get();
            return new DoubleConst(lex.getDouble(), token);
        default :
            break;
        }

        String str;
        ASTree index;
        ASTree expr = parsePrimaryExpr(tbl);
        int t;
        while (true) {
            switch (lex.lookAhead()) {
            case '(' :
                expr = parseMethodCall(tbl, expr);
                break;
            case '[' :
                if (lex.lookAhead(1) == ']') {
                    int dim = parseArrayDimension();
                    if (lex.get() != '.' || lex.get() != CLASS)
                        throw new SyntaxError(lex);

                    expr = parseDotClass(expr, dim);
                }
                else {
                    index = parseArrayIndex(tbl);
                    if (index == null)
                        throw new SyntaxError(lex);

                    expr = Expr.make(ARRAY, expr, index);
                }
                break;
            case PLUSPLUS :
            case MINUSMINUS :
                t = lex.get();
                expr = Expr.make(t, null, expr);
                break;
            case '.' :
                lex.get();
                t = lex.get();
                if (t == CLASS) {
                    expr = parseDotClass(expr, 0);
                }
                else if (t == Identifier) {
                    str = lex.getString();
                    expr = Expr.make('.', expr, new Member(str));
                }
                else
                    throw new CompileError("missing member name", lex);
                break;
            case '#' :
                lex.get();
                t = lex.get();
                if (t != Identifier)
                    throw new CompileError("missing static member name", lex);

                str = lex.getString();
                expr = Expr.make(MEMBER, new Symbol(toClassName(expr)),
                                 new Member(str));
                break;
            default :
                return expr;
            }
        }
    }

    /* Parse a .class expression on a class type.  For example,
     * String.class   => ('.' "String" "class")
     * String[].class => ('.' "[LString;" "class")
     */
    private ASTree parseDotClass(ASTree className, int dim)
        throws CompileError
    {
        String cname = toClassName(className);
        if (dim > 0) {
            StringBuffer sbuf = new StringBuffer();
            while (dim-- > 0)
                sbuf.append('[');

            sbuf.append('L').append(cname.replace('.', '/')).append(';');
            cname = sbuf.toString();
        }

        return Expr.make('.', new Symbol(cname), new Member("class"));
    }

    /* Parses a .class expression on a built-in type.  For example,
     * int.class   => ('#' "java.lang.Integer" "TYPE")
     * int[].class => ('.' "[I", "class")
     */
    private ASTree parseDotClass(int builtinType, int dim)
        throws CompileError
    {
        if (dim > 0) {
            String cname = CodeGen.toJvmTypeName(builtinType, dim);
            return Expr.make('.', new Symbol(cname), new Member("class"));
        }
        else {
            String cname;
            switch(builtinType) {
            case BOOLEAN :
                cname = "java.lang.Boolean";
                break;
            case BYTE :
                cname = "java.lang.Byte";
                break;
            case CHAR :
                cname = "java.lang.Character";
                break;
            case SHORT :
                cname = "java.lang.Short";
                break;
            case INT :
                cname = "java.lang.Integer";
                break;
            case LONG :
                cname = "java.lang.Long";
                break;
            case FLOAT :
                cname = "java.lang.Float";
                break;
            case DOUBLE :
                cname = "java.lang.Double";
                break;
            case VOID :
                cname = "java.lang.Void";
                break;
            default :
                throw new CompileError("invalid builtin type: "
                                       + builtinType);
            }

            return Expr.make(MEMBER, new Symbol(cname), new Member("TYPE"));
        }
    }

    /* method.call : method.expr "(" argument.list ")"
     * method.expr : THIS | SUPER | Identifier
     *             | postfix.expr "." Identifier
     *             | postfix.expr "#" Identifier
     */
    private ASTree parseMethodCall(SymbolTable tbl, ASTree expr)
        throws CompileError
    {
        if (expr instanceof Keyword) {
            int token = ((Keyword)expr).get();
            if (token != THIS && token != SUPER)
                throw new SyntaxError(lex);
        }
        else if (expr instanceof Symbol)        // Identifier
            ;
        else if (expr instanceof Expr) {
            int op = ((Expr)expr).getOperator();
            if (op != '.' && op != MEMBER)
                throw new SyntaxError(lex);
        }

        return CallExpr.makeCall(expr, parseArgumentList(tbl));
    }

    private String toClassName(ASTree name)
        throws CompileError
    {
        StringBuffer sbuf = new StringBuffer();
        toClassName(name, sbuf);
        return sbuf.toString();
    }

    private void toClassName(ASTree name, StringBuffer sbuf)
        throws CompileError
    {
        if (name instanceof Symbol) {
            sbuf.append(((Symbol)name).get());
            return;
        }
        else if (name instanceof Expr) {
            Expr expr = (Expr)name;
            if (expr.getOperator() == '.') {
                toClassName(expr.oprand1(), sbuf);
                sbuf.append('.');
                toClassName(expr.oprand2(), sbuf);
                return;
            }
        }

        throw new CompileError("bad static member access", lex);
    }

    /* primary.expr : THIS | SUPER | TRUE | FALSE | NULL
     *              | StringL
     *              | Identifier
     *              | NEW new.expr
     *              | "(" expression ")"
     *              | builtin.type ( "[" "]" )* "." CLASS
     *
     * Identifier represents either a local variable name, a member name,
     * or a class name.
     */
    private ASTree parsePrimaryExpr(SymbolTable tbl) throws CompileError {
        int t;
        String name;
        Declarator decl;
        ASTree expr;

        switch (t = lex.get()) {
        case THIS :
        case SUPER :
        case TRUE :
        case FALSE :
        case NULL :
            return new Keyword(t);
        case Identifier :
            name = lex.getString();
            decl = tbl.lookup(name);
            if (decl == null)
                return new Member(name);        // this or static member
            else
                return new Variable(name, decl); // local variable
        case StringL :
            return new StringL(lex.getString());
        case NEW :
            return parseNew(tbl);
        case '(' :
            expr = parseExpression(tbl);
            if (lex.get() == ')')
                return expr;
            else
                throw new CompileError(") is missing", lex);
        default :
            if (isBuiltinType(t) || t == VOID) {
                int dim = parseArrayDimension();
                if (lex.get() == '.' && lex.get() == CLASS)
                    return parseDotClass(t, dim);
            }

            throw new SyntaxError(lex);
        }
    }

    /* new.expr : class.type "(" argument.list ")"
     *          | class.type     array.size [ array.initializer ]
     *          | primitive.type array.size [ array.initializer ]
     */
    private NewExpr parseNew(SymbolTable tbl) throws CompileError {
        ArrayInit init = null;
        int t = lex.lookAhead();
        if (isBuiltinType(t)) {
            lex.get();
            ASTList size = parseArraySize(tbl);
            if (lex.lookAhead() == '{')
                init = parseArrayInitializer(tbl);

            return new NewExpr(t, size, init);
        }
        else if (t == Identifier) {
            ASTList name = parseClassType(tbl);
            t = lex.lookAhead();
            if (t == '(') {
                ASTList args = parseArgumentList(tbl);
                return new NewExpr(name, args);
            }
            else if (t == '[') {
                ASTList size = parseArraySize(tbl);
                if (lex.lookAhead() == '{')
                    init = parseArrayInitializer(tbl);

                return NewExpr.makeObjectArray(name, size, init);
            }
        }

        throw new SyntaxError(lex);
    }

    /* array.size : [ array.index ]*
     */
    private ASTList parseArraySize(SymbolTable tbl) throws CompileError {
        ASTList list = null;
        while (lex.lookAhead() == '[')
            list = ASTList.append(list, parseArrayIndex(tbl));

        return list;
    }

    /* array.index : "[" [ expression ] "]"
     */
    private ASTree parseArrayIndex(SymbolTable tbl) throws CompileError {
        lex.get();      // '['
        if (lex.lookAhead() == ']') {
            lex.get();
            return null;
        }
        else {
            ASTree index = parseExpression(tbl);
            if (lex.get() != ']')
                throw new CompileError("] is missing", lex);

            return index;
        }
    }

    /* argument.list : "(" [ expression [ "," expression ]* ] ")"
     */
    private ASTList parseArgumentList(SymbolTable tbl) throws CompileError {
        if (lex.get() != '(')
            throw new CompileError("( is missing", lex);

        ASTList list = null;
        if (lex.lookAhead() != ')')
            for (;;) {
                list = ASTList.append(list, parseExpression(tbl));
                if (lex.lookAhead() == ',')
                    lex.get();
                else
                    break;
            }

        if (lex.get() != ')')
            throw new CompileError(") is missing", lex);

        return list;
    }
}