1 /*

     2  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  */

    23 

    24 public class Surrogate {

    25 

    26     public static final int UCS4_SURROGATE_MIN = 0x10000;

    27     public static final int UCS4_MAX = (1 << 20) + UCS4_SURROGATE_MIN - 1;

    28 

    29     // UTF-16 surrogate-character ranges

    30     //

    31     public static final char MIN_HIGH = '\uD800';

    32     public static final char MAX_HIGH = '\uDBFF';

    33     public static final char MIN_LOW  = '\uDC00';

    34     public static final char MAX_LOW  = '\uDFFF';

    35     public static final char MIN = MIN_HIGH;

    36     public static final char MAX = MAX_LOW;

    37 

    38     public static boolean neededFor(int uc) {

    39         return (uc >= UCS4_SURROGATE_MIN) && (uc <= UCS4_MAX);

    40     }

    41 

    42     public static boolean isHigh(int c) {

    43         return (MIN_HIGH <= c) && (c <= MAX_HIGH);

    44     }

    45 

    46     static char high(int uc) {

    47         return (char)(0xd800 | (((uc - UCS4_SURROGATE_MIN) >> 10) & 0x3ff));

    48     }

    49 

    50     public static boolean isLow(int c) {

    51         return (MIN_LOW <= c) && (c <= MAX_LOW);

    52     }

    53 

    54     static char low(int uc) {

    55         return (char)(0xdc00 | ((uc - UCS4_SURROGATE_MIN) & 0x3ff));

    56     }

    57 

    58     public static boolean is(int c) {

    59         return (MIN <= c) && (c <= MAX);

    60     }

    61 

    62     static int toUCS4(char c, char d) {

    63         return (((c & 0x3ff) << 10) | (d & 0x3ff)) + 0x10000;

    64     }

    65 

    66 }