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 "WriteBarrier.h"
  30
  31 #include <wtf/FixedArray.h>
  32 #include <wtf/Noncopyable.h>
  33 #include <wtf/OwnPtr.h>
  34
  35 #define JSC_COMMON_STRINGS_EACH_NAME(macro) \
  36     macro(boolean) \
  37     macro(false) \
  38     macro(function) \
  39     macro(number) \
  40     macro(null) \
  41     macro(object) \
  42     macro(undefined) \
  43     macro(string) \
  44     macro(true)
  45
  46 namespace WTF {
  47 class StringImpl;
  48 }
  49
  50 namespace JSC {
  51
  52     class HeapRootVisitor;
  53     class VM;
  54     class JSString;
  55     class SmallStringsStorage;
  56     class SlotVisitor;
  57
  58     static const unsigned maxSingleCharacterString = 0xFF;
  59
  60     class SmallStrings {
  61         WTF_MAKE_NONCOPYABLE(SmallStrings);
  62     public:
  63         SmallStrings();
  64         ~SmallStrings();
  65
  66         JSString* emptyString()
  67         {
  68             return m_emptyString;
  69         }
  70
  71         JSString* singleCharacterString(VM* vm, unsigned char character)
  72         {
  73             if (!m_singleCharacterStrings[character])
  74                 createSingleCharacterString(vm, character);
  75             return m_singleCharacterStrings[character];
  76         }
  77
  78         JS_EXPORT_PRIVATE WTF::StringImpl* singleCharacterStringRep(unsigned char character);
  79
  80         void finalizeSmallStrings();
  81
  82         JSString** singleCharacterStrings() { return &m_singleCharacterStrings[0]; }
  83
  84         void initializeCommonStrings(VM&);
  85         void visitStrongReferences(SlotVisitor&);
  86
  87 #define JSC_COMMON_STRINGS_ACCESSOR_DEFINITION(name) \
  88         JSString* name##String() const \
  89         { \
  90             return m_##name; \
  91         }
  92         JSC_COMMON_STRINGS_EACH_NAME(JSC_COMMON_STRINGS_ACCESSOR_DEFINITION)
  93 #undef JSC_COMMON_STRINGS_ACCESSOR_DEFINITION
  94
  95     private:
  96         static const unsigned singleCharacterStringCount = maxSingleCharacterString + 1;
  97
  98         JS_EXPORT_PRIVATE void createEmptyString(VM*);
  99         JS_EXPORT_PRIVATE void createSingleCharacterString(VM*, unsigned char);
 100
 101         void initialize(VM* vm, JSString*& string, const char* value) const;
 102
 103         JSString* m_emptyString;
 104 #define JSC_COMMON_STRINGS_ATTRIBUTE_DECLARATION(name) JSString* m_##name;
 105         JSC_COMMON_STRINGS_EACH_NAME(JSC_COMMON_STRINGS_ATTRIBUTE_DECLARATION)
 106 #undef JSC_COMMON_STRINGS_ATTRIBUTE_DECLARATION
 107         JSString* m_singleCharacterStrings[singleCharacterStringCount];
 108         OwnPtr<SmallStringsStorage> m_storage;
 109     };
 110
 111 } // namespace JSC
 112
 113 #endif // SmallStrings_h