1/*
2 * Copyright (C) 2008 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1.  Redistributions of source code must retain the above copyright
9 *     notice, this list of conditions and the following disclaimer.
10 * 2.  Redistributions in binary form must reproduce the above copyright
11 *     notice, this list of conditions and the following disclaimer in the
12 *     documentation and/or other materials provided with the distribution.
13 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
14 *     its contributors may be used to endorse or promote products derived
15 *     from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY 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
29#ifndef AtomicStringHash_h
30#define AtomicStringHash_h
31
32#include "wtf/text/AtomicString.h"
33#include "wtf/HashTraits.h"
34
35namespace WTF {
36
37    struct AtomicStringHash {
38        static unsigned hash(const AtomicString& key)
39        {
40            return key.impl()->existingHash();
41        }
42
43        static bool equal(const AtomicString& a, const AtomicString& b)
44        {
45            return a == b;
46        }
47
48        static const bool safeToCompareToEmptyOrDeleted = false;
49    };
50
51    // AtomicStringHash is the default hash for AtomicString
52    template<> struct HashTraits<WTF::AtomicString> : GenericHashTraits<WTF::AtomicString> {
53        // Unlike other types, we can return a const reference for AtomicString's empty value (nullAtom).
54        typedef const WTF::AtomicString& PeekOutType;
55
56        static const WTF::AtomicString& emptyValue() { return nullAtom; }
57        static PeekOutType peek(const WTF::AtomicString& value) { return value; }
58
59        static const bool emptyValueIsZero = true;
60        static void constructDeletedValue(WTF::AtomicString& slot, bool) { new (NotNull, &slot) WTF::AtomicString(HashTableDeletedValue); }
61        static bool isDeletedValue(const WTF::AtomicString& slot) { return slot.isHashTableDeletedValue(); }
62    };
63
64}
65
66using WTF::AtomicStringHash;
67
68#endif
69