runtime/SmallStrings.h

   1 /*
   2  * Copyright (C) 2008, 2009 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 #ifndef SmallStrings_h
  27 #define SmallStrings_h
  28
  29 #include "UString.h"
  30 #include <wtf/FixedArray.h>
  31 #include <wtf/OwnPtr.h>
  32
  33 #define JSC_COMMON_STRINGS_EACH_NAME(macro) \
  34     macro(boolean) \
  35     macro(false) \
  36     macro(function) \
  37     macro(number) \
  38     macro(null) \
  39     macro(object) \
  40     macro(undefined) \
  41     macro(string) \
  42     macro(true)
  43
  44 namespace JSC {
  45
  46     class HeapRootVisitor;
  47     class JSGlobalData;
  48     class JSString;
  49     class SmallStringsStorage;
  50     class SlotVisitor;
  51
  52     static const unsigned maxSingleCharacterString = 0xFF;
  53
  54     class SmallStrings {
  55         WTF_MAKE_NONCOPYABLE(SmallStrings);
  56     public:
  57         SmallStrings();
  58         ~SmallStrings();
  59
  60         JSString* emptyString(JSGlobalData* globalData)
  61         {
  62             if (!m_emptyString)
  63                 createEmptyString(globalData);
  64             return m_emptyString;
  65         }
  66
  67         JSString* singleCharacterString(JSGlobalData* globalData, unsigned char character)
  68         {
  69             if (!m_singleCharacterStrings[character])
  70                 createSingleCharacterString(globalData, character);
  71             return m_singleCharacterStrings[character];
  72         }
  73
  74         JS_EXPORT_PRIVATE StringImpl* singleCharacterStringRep(unsigned char character);
  75
  76         void finalizeSmallStrings();
  77
  78         JSString** singleCharacterStrings() { return &m_singleCharacterStrings[0]; }
  79
  80 #define JSC_COMMON_STRINGS_ACCESSOR_DEFINITION(name) \
  81         JSString* name##String(JSGlobalData* globalData) const \
  82         { \
  83             if (!m_##name) \
  84                 initialize(globalData, m_##name, #name); \
  85             return m_##name; \
  86         }
  87         JSC_COMMON_STRINGS_EACH_NAME(JSC_COMMON_STRINGS_ACCESSOR_DEFINITION)
  88 #undef JSC_COMMON_STRINGS_ACCESSOR_DEFINITION
  89
  90     private:
  91         static const unsigned singleCharacterStringCount = maxSingleCharacterString + 1;
  92
  93         JS_EXPORT_PRIVATE void createEmptyString(JSGlobalData*);
  94         JS_EXPORT_PRIVATE void createSingleCharacterString(JSGlobalData*, unsigned char);
  95
  96         void initialize(JSGlobalData* globalData, JSString*& string, const char* value) const;
  97
  98         JSString* m_emptyString;
  99 #define JSC_COMMON_STRINGS_ATTRIBUTE_DECLARATION(name) mutable JSString* m_##name;
 100         JSC_COMMON_STRINGS_EACH_NAME(JSC_COMMON_STRINGS_ATTRIBUTE_DECLARATION)
 101 #undef JSC_COMMON_STRINGS_ATTRIBUTE_DECLARATION
 102         JSString* m_singleCharacterStrings[singleCharacterStringCount];
 103         OwnPtr<SmallStringsStorage> m_storage;
 104     };
 105
 106 } // namespace JSC
 107
 108 #endif // SmallStrings_h