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 | |
34 | namespace JSC { |
35 | static const unsigned numCharactersToStore = 0x100; |
36 | |
37 | class SmallStringsStorage : public Noncopyable { |
38 | public: |
39 | SmallStringsStorage(); |
40 | |
41 | UString::Rep* rep(unsigned char character) { return &m_reps[character]; } |
42 | |
43 | private: |
44 | UString::Rep m_reps[numCharactersToStore]; |
45 | }; |
46 | |
47 | SmallStringsStorage::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 | |
57 | SmallStrings::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 | |
67 | SmallStrings::~SmallStrings() |
68 | { |
69 | } |
70 | |
71 | void 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 | |
81 | unsigned 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 | |
93 | void SmallStrings::createEmptyString(JSGlobalData* globalData) |
94 | { |
95 | ASSERT(!m_emptyString); |
96 | m_emptyString = new (globalData) JSString(globalData, "" , JSString::HasOtherOwner); |
97 | } |
98 | |
99 | void 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 | |
107 | UString::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 | |