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 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
14 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
17 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
18 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
19 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
20 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
21 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
23 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#include "config.h"
27#include "SmallStrings.h"
28
29#include "JSGlobalObject.h"
30#include "JSString.h"
31
32#include <wtf/Noncopyable.h>
33
34namespace JSC {
35static const unsigned numCharactersToStore = 0x100;
36
37class SmallStringsStorage : public Noncopyable {
38public:
39 SmallStringsStorage();
40
41 UString::Rep* rep(unsigned char character) { return &m_reps[character]; }
42
43private:
44 UString::Rep m_reps[numCharactersToStore];
45};
46
47SmallStringsStorage::SmallStringsStorage()
48{
49 UChar* characterBuffer = 0;
50 RefPtr<UStringImpl> baseString = UStringImpl::createUninitialized(length: numCharactersToStore, output&: characterBuffer);
51 for (unsigned i = 0; i < numCharactersToStore; ++i) {
52 characterBuffer[i] = i;
53 new (&m_reps[i]) UString::Rep(&characterBuffer[i], 1, PassRefPtr<UStringImpl>(baseString));
54 }
55}
56
57SmallStrings::SmallStrings()
58 : m_emptyString(0)
59 , m_storage(0)
60{
61 COMPILE_ASSERT(numCharactersToStore == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage);
62
63 for (unsigned i = 0; i < numCharactersToStore; ++i)
64 m_singleCharacterStrings[i] = 0;
65}
66
67SmallStrings::~SmallStrings()
68{
69}
70
71void SmallStrings::markChildren(MarkStack& markStack)
72{
73 if (m_emptyString)
74 markStack.append(cell: m_emptyString);
75 for (unsigned i = 0; i < numCharactersToStore; ++i) {
76 if (m_singleCharacterStrings[i])
77 markStack.append(cell: m_singleCharacterStrings[i]);
78 }
79}
80
81unsigned SmallStrings::count() const
82{
83 unsigned count = 0;
84 if (m_emptyString)
85 ++count;
86 for (unsigned i = 0; i < numCharactersToStore; ++i) {
87 if (m_singleCharacterStrings[i])
88 ++count;
89 }
90 return count;
91}
92
93void SmallStrings::createEmptyString(JSGlobalData* globalData)
94{
95 ASSERT(!m_emptyString);
96 m_emptyString = new (globalData) JSString(globalData, "", JSString::HasOtherOwner);
97}
98
99void SmallStrings::createSingleCharacterString(JSGlobalData* globalData, unsigned char character)
100{
101 if (!m_storage)
102 m_storage.set(new SmallStringsStorage);
103 ASSERT(!m_singleCharacterStrings[character]);
104 m_singleCharacterStrings[character] = new (globalData) JSString(globalData, m_storage->rep(character), JSString::HasOtherOwner);
105}
106
107UString::Rep* SmallStrings::singleCharacterStringRep(unsigned char character)
108{
109 if (!m_storage)
110 m_storage.set(new SmallStringsStorage);
111 return m_storage->rep(character);
112}
113
114} // namespace JSC
115

source code of qtscript/src/3rdparty/javascriptcore/JavaScriptCore/runtime/SmallStrings.cpp