1/*
2 * [The "BSD license"]
3 *  Copyright (c) 2010 Terence Parr
4 *  All rights reserved.
5 *
6 *  Redistribution and use in source and binary forms, with or without
7 *  modification, are permitted provided that the following conditions
8 *  are met:
9 *  1. Redistributions of source code must retain the above copyright
10 *      notice, this list of conditions and the following disclaimer.
11 *  2. Redistributions in binary form must reproduce the above copyright
12 *      notice, this list of conditions and the following disclaimer in the
13 *      documentation and/or other materials provided with the distribution.
14 *  3. The name of the author may not be used to endorse or promote products
15 *      derived from this software without specific prior written permission.
16 *
17 *  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 *  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 *  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 *  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 *  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29package org.antlr.codegen;
30
31public class JavaScriptTarget extends Target {
32    /** Convert an int to a JavaScript Unicode character literal.
33     *
34     *  The current JavaScript spec (ECMA-262) doesn't provide for octal
35     *  notation in String literals, although some implementations support it.
36     *  This method overrides the parent class so that characters will always
37     *  be encoded as Unicode literals (e.g. \u0011).
38     */
39    public String encodeIntAsCharEscape(int v) {
40        String hex = Integer.toHexString(v|0x10000).substring(1,5);
41        return "\\u"+hex;
42    }
43
44    /** Convert long to two 32-bit numbers separted by a comma.
45     *  JavaScript does not support 64-bit numbers, so we need to break
46     *  the number into two 32-bit literals to give to the Bit.  A number like
47     *  0xHHHHHHHHLLLLLLLL is broken into the following string:
48     *  "0xLLLLLLLL, 0xHHHHHHHH"
49     *  Note that the low order bits are first, followed by the high order bits.
50     *  This is to match how the BitSet constructor works, where the bits are
51     *  passed in in 32-bit chunks with low-order bits coming first.
52     *
53     *  Note: stole the following two methods from the ActionScript target.
54     */
55    public String getTarget64BitStringFromValue(long word) {
56        StringBuffer buf = new StringBuffer(22); // enough for the two "0x", "," and " "
57        buf.append("0x");
58        writeHexWithPadding(buf, Integer.toHexString((int)(word & 0x00000000ffffffffL)));
59        buf.append(", 0x");
60        writeHexWithPadding(buf, Integer.toHexString((int)(word >> 32)));
61
62        return buf.toString();
63    }
64
65    private void writeHexWithPadding(StringBuffer buf, String digits) {
66        digits = digits.toUpperCase();
67        int padding = 8 - digits.length();
68        // pad left with zeros
69        for (int i=1; i<=padding; i++) {
70            buf.append('0');
71        }
72        buf.append(digits);
73    }
74}
75