lex.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

                            ungetc(c);
                            return IntConstant;
                        }
                    }
                }
            }

        value = c - '0';
        while ('0' <= c2 && c2 <= '9') {
            value = value * 10 + c2 - '0';
            c2 = getc();
        }

        token.longValue = value;
        if (c2 == 'F' || c2 == 'f') {
            token.doubleValue = (double)value;
            return FloatConstant;
        }
        else if (c2 == 'E' || c2 == 'e'
                 || c2 == 'D' || c2 == 'd' || c2 == '.') {
            StringBuffer tbuf = textBuffer;
            tbuf.setLength(0);
            tbuf.append(value);
            return readDouble(tbuf, c2, token);
        }
        else if (c2 == 'L' || c2 == 'l')
            return LongConstant;
        else {
            ungetc(c2);
            return IntConstant;
        }
    }

    private int readDouble(StringBuffer sbuf, int c, Token token) {
        if (c != 'E' && c != 'e' && c != 'D' && c != 'd') {
            sbuf.append((char)c);
            for (;;) {
                c = getc();
                if ('0' <= c && c <= '9')
                    sbuf.append((char)c);
                else
                    break;
            }
        }

        if (c == 'E' || c == 'e') {
            sbuf.append((char)c);
            c = getc();
            if (c == '+' || c == '-') {
                sbuf.append((char)c);
                c = getc();
            }

            while ('0' <= c && c <= '9') {
                sbuf.append((char)c);
                c = getc();
            }
        }

        try {
            token.doubleValue = Double.parseDouble(sbuf.toString());
        }
        catch (NumberFormatException e) {
            return BadToken;
        }

        if (c == 'F' || c == 'f')
            return FloatConstant;
        else {
            if (c != 'D' && c != 'd')
                ungetc(c);

            return DoubleConstant;
        }
    }

    // !"#$%&'(    )*+,-./0    12345678    9:;<=>?
    private static final int[] equalOps
        =  { NEQ, 0, 0, 0, MOD_E, AND_E, 0, 0,
             0, MUL_E, PLUS_E, 0, MINUS_E, 0, DIV_E, 0,
             0, 0, 0, 0, 0, 0, 0, 0,
             0, 0, 0, LE, EQ, GE, 0 };

    private int readSeparator(int c) {
        int c2, c3;
        if ('!' <= c && c <= '?') {
            int t = equalOps[c - '!'];
            if (t == 0) 
                return c;
            else {
                c2 = getc();
                if (c == c2)
                    switch (c) {
                    case '=' :
                        return EQ;
                    case '+' :
                        return PLUSPLUS;
                    case '-' :
                        return MINUSMINUS;
                    case '&' :
                        return ANDAND;
                    case '<' :
                        c3 = getc();
                        if (c3 == '=')
                            return LSHIFT_E;
                        else {
                            ungetc(c3);
                            return LSHIFT;
                        }
                    case '>' :
                        c3 = getc();
                        if (c3 == '=')
                            return RSHIFT_E;
                        else if (c3 == '>') {
                            c3 = getc();
                            if (c3 == '=')
                                return ARSHIFT_E;
                            else {
                                ungetc(c3);
                                return ARSHIFT;
                            }
                        }
                        else {
                            ungetc(c3);
                            return RSHIFT;
                        }
                    default :
                        break;
                    }
                else if (c2 == '=')
                    return t;
            }
        }
        else if (c == '^') {
            c2 = getc();
            if (c2 == '=')
                return EXOR_E;
        }
        else if (c == '|') {
            c2 = getc();
            if (c2 == '=')
                return OR_E;
            else if (c2 == '|')
                return OROR;
        }
        else
            return c;

        ungetc(c2);
        return c;
    }

    private int readIdentifier(int c, Token token) {
        StringBuffer tbuf = textBuffer;
        tbuf.setLength(0);

        do {
            tbuf.append((char)c);
            c = getc();
        } while (Character.isJavaIdentifierPart((char)c));

        ungetc(c);

        String name = tbuf.toString();
        int t = ktable.lookup(name);
        if (t >= 0)
            return t;
        else {
            /* tbuf.toString() is executed quickly since it does not
             * need memory copy.  Using a hand-written extensible
             * byte-array class instead of StringBuffer is not a good idea
             * for execution speed.  Converting a byte array to a String
             * object is very slow.  Using an extensible char array
             * might be OK.
             */
            token.textValue = name;
            return Identifier;
        }
    }

    private static final KeywordTable ktable = new KeywordTable();

    static {
        ktable.append("abstract", ABSTRACT);
        ktable.append("boolean", BOOLEAN);
        ktable.append("break", BREAK);
        ktable.append("byte", BYTE);
        ktable.append("case", CASE);
        ktable.append("catch", CATCH);
        ktable.append("char", CHAR);
        ktable.append("class", CLASS);
        ktable.append("const", CONST);
        ktable.append("continue", CONTINUE);
        ktable.append("default", DEFAULT);
        ktable.append("do", DO);
        ktable.append("double", DOUBLE);
        ktable.append("else", ELSE);
        ktable.append("extends", EXTENDS);
        ktable.append("false", FALSE);
        ktable.append("final", FINAL);
        ktable.append("finally", FINALLY);
        ktable.append("float", FLOAT);
        ktable.append("for", FOR);
        ktable.append("goto", GOTO);
        ktable.append("if", IF);
        ktable.append("implements", IMPLEMENTS);
        ktable.append("import", IMPORT);
        ktable.append("instanceof", INSTANCEOF);
        ktable.append("int", INT);
        ktable.append("interface", INTERFACE);
        ktable.append("long", LONG);
        ktable.append("native", NATIVE);
        ktable.append("new", NEW);
        ktable.append("null", NULL);
        ktable.append("package", PACKAGE);
        ktable.append("private", PRIVATE);
        ktable.append("protected", PROTECTED);
        ktable.append("public", PUBLIC);
        ktable.append("return", RETURN);
        ktable.append("short", SHORT);
        ktable.append("static", STATIC);
        ktable.append("strictfp", STRICT);
        ktable.append("super", SUPER);
        ktable.append("switch", SWITCH);
        ktable.append("synchronized", SYNCHRONIZED);
        ktable.append("this", THIS);
        ktable.append("throw", THROW);
        ktable.append("throws", THROWS);
        ktable.append("transient", TRANSIENT);
        ktable.append("true", TRUE);
        ktable.append("try", TRY);
        ktable.append("void", VOID);
        ktable.append("volatile", VOLATILE);
        ktable.append("while", WHILE);
    }

    private static boolean isBlank(int c) {
        return c == ' ' || c == '\t' || c == '\f' || c == '\r'
            || c == '\n';
    }

    private static boolean isDigit(int c) {
        return '0' <= c && c <= '9';
    }

    private void ungetc(int c) {
        lastChar = c;
    }

    public String getTextAround() {
        int begin = position - 10;
        if (begin < 0)
            begin = 0;

        int end = position + 10;
        if (end > maxlen)
            end = maxlen;

        return input.substring(begin, end);
    }

    private int getc() {
        if (lastChar < 0)
            if (position < maxlen)
                return input.charAt(position++);
            else
                return -1;
        else {
            int c = lastChar;
            lastChar = -1;
            return c;
        }
    }
}