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