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 : Noncopyable { 38 public: 39 SmallStringsStorage(); 40 rep(unsigned char character)41 UString::Rep* rep(unsigned char character) { return &m_reps[character]; } 42 43 private: 44 UChar m_characters[numCharactersToStore]; 45 UString::BaseString m_base; 46 UString::Rep m_reps[numCharactersToStore]; 47 }; 48 SmallStringsStorage()49 SmallStringsStorage::SmallStringsStorage() 50 { 51 for (unsigned i = 0; i < numCharactersToStore; ++i) 52 m_characters[i] = i; 53 54 m_base.rc = numCharactersToStore + 1; 55 m_base.buf = m_characters; 56 m_base.len = numCharactersToStore; 57 m_base.offset = 0; 58 m_base._hash = 0; 59 m_base.m_baseString = 0; 60 m_base.preCapacity = 0; 61 m_base.usedPreCapacity = 0; 62 m_base.reportedCost = 0; 63 64 // make sure UString doesn't try to reuse the buffer by pretending we have one more character in it 65 m_base.usedCapacity = numCharactersToStore + 1; 66 m_base.capacity = numCharactersToStore + 1; 67 m_base.checkConsistency(); 68 69 memset(&m_reps, 0, sizeof(m_reps)); 70 for (unsigned i = 0; i < numCharactersToStore; ++i) { 71 m_reps[i].offset = i; 72 m_reps[i].len = 1; 73 m_reps[i].rc = 1; 74 m_reps[i].setBaseString(&m_base); 75 m_reps[i].checkConsistency(); 76 } 77 } 78 SmallStrings()79 SmallStrings::SmallStrings() 80 : m_emptyString(0) 81 , m_storage(0) 82 { 83 COMPILE_ASSERT(numCharactersToStore == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage); 84 85 for (unsigned i = 0; i < numCharactersToStore; ++i) 86 m_singleCharacterStrings[i] = 0; 87 } 88 ~SmallStrings()89 SmallStrings::~SmallStrings() 90 { 91 } 92 mark()93 void SmallStrings::mark() 94 { 95 if (m_emptyString && !m_emptyString->marked()) 96 m_emptyString->mark(); 97 for (unsigned i = 0; i < numCharactersToStore; ++i) { 98 if (m_singleCharacterStrings[i] && !m_singleCharacterStrings[i]->marked()) 99 m_singleCharacterStrings[i]->mark(); 100 } 101 } 102 count() const103 unsigned SmallStrings::count() const 104 { 105 unsigned count = 0; 106 if (m_emptyString) 107 ++count; 108 for (unsigned i = 0; i < numCharactersToStore; ++i) { 109 if (m_singleCharacterStrings[i]) 110 ++count; 111 } 112 return count; 113 } 114 createEmptyString(JSGlobalData * globalData)115 void SmallStrings::createEmptyString(JSGlobalData* globalData) 116 { 117 ASSERT(!m_emptyString); 118 m_emptyString = new (globalData) JSString(globalData, "", JSString::HasOtherOwner); 119 } 120 createSingleCharacterString(JSGlobalData * globalData,unsigned char character)121 void SmallStrings::createSingleCharacterString(JSGlobalData* globalData, unsigned char character) 122 { 123 if (!m_storage) 124 m_storage.set(new SmallStringsStorage); 125 ASSERT(!m_singleCharacterStrings[character]); 126 m_singleCharacterStrings[character] = new (globalData) JSString(globalData, m_storage->rep(character), JSString::HasOtherOwner); 127 } 128 singleCharacterStringRep(unsigned char character)129 UString::Rep* SmallStrings::singleCharacterStringRep(unsigned char character) 130 { 131 if (!m_storage) 132 m_storage.set(new SmallStringsStorage); 133 return m_storage->rep(character); 134 } 135 136 } // namespace JSC 137