runtime/PropertySlot.h

   1 /*
   2  *  Copyright (C) 2005, 2007, 2008 Apple Inc. All rights reserved.
   3  *
   4  *  This library is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU Library General Public
   6  *  License as published by the Free Software Foundation; either
   7  *  version 2 of the License, or (at your option) any later version.
   8  *
   9  *  This library is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  *  Library General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU Library General Public License
  15  *  along with this library; see the file COPYING.LIB.  If not, write to
  16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  17  *  Boston, MA 02110-1301, USA.
  18  *
  19  */
  20
  21 #ifndef PropertySlot_h
  22 #define PropertySlot_h
  23
  24 #include "Identifier.h"
  25 #include "JSValue.h"
  26 #include "Register.h"
  27 #include <wtf/Assertions.h>
  28 #include <wtf/NotFound.h>
  29
  30 namespace JSC {
  31
  32     class ExecState;
  33     class JSObject;
  34
  35 #define JSC_VALUE_SLOT_MARKER 0
  36 #define JSC_REGISTER_SLOT_MARKER reinterpret_cast<GetValueFunc>(1)
  37
  38     class PropertySlot {
  39     public:
  40         PropertySlot()
  41         {
  42             clearBase();
  43             clearOffset();
  44             clearValue();
  45         }
  46
  47         explicit PropertySlot(const JSValue base)
  48             : m_slotBase(base)
  49         {
  50             clearOffset();
  51             clearValue();
  52         }
  53
  54         typedef JSValue (*GetValueFunc)(ExecState*, const Identifier&, const PropertySlot&);
  55
  56         JSValue getValue(ExecState* exec, const Identifier& propertyName) const
  57         {
  58             if (m_getValue == JSC_VALUE_SLOT_MARKER)
  59                 return *m_data.valueSlot;
  60             if (m_getValue == JSC_REGISTER_SLOT_MARKER)
  61                 return (*m_data.registerSlot).jsValue();
  62             return m_getValue(exec, propertyName, *this);
  63         }
  64
  65         JSValue getValue(ExecState* exec, unsigned propertyName) const
  66         {
  67             if (m_getValue == JSC_VALUE_SLOT_MARKER)
  68                 return *m_data.valueSlot;
  69             if (m_getValue == JSC_REGISTER_SLOT_MARKER)
  70                 return (*m_data.registerSlot).jsValue();
  71             return m_getValue(exec, Identifier::from(exec, propertyName), *this);
  72         }
  73
  74         bool isCacheable() const { return m_offset != WTF::notFound; }
  75         size_t cachedOffset() const
  76         {
  77             ASSERT(isCacheable());
  78             return m_offset;
  79         }
  80
  81         void setValueSlot(JSValue* valueSlot)
  82         {
  83             ASSERT(valueSlot);
  84             clearBase();
  85             clearOffset();
  86             m_getValue = JSC_VALUE_SLOT_MARKER;
  87             m_data.valueSlot = valueSlot;
  88         }
  89
  90         void setValueSlot(JSValue slotBase, JSValue* valueSlot)
  91         {
  92             ASSERT(valueSlot);
  93             m_getValue = JSC_VALUE_SLOT_MARKER;
  94             m_slotBase = slotBase;
  95             m_data.valueSlot = valueSlot;
  96         }
  97
  98         void setValueSlot(JSValue slotBase, JSValue* valueSlot, size_t offset)
  99         {
 100             ASSERT(valueSlot);
 101             m_getValue = JSC_VALUE_SLOT_MARKER;
 102             m_slotBase = slotBase;
 103             m_data.valueSlot = valueSlot;
 104             m_offset = offset;
 105         }
 106
 107         void setValue(JSValue value)
 108         {
 109             ASSERT(value);
 110             clearBase();
 111             clearOffset();
 112             m_getValue = JSC_VALUE_SLOT_MARKER;
 113             m_value = value;
 114             m_data.valueSlot = &m_value;
 115         }
 116
 117         void setRegisterSlot(Register* registerSlot)
 118         {
 119             ASSERT(registerSlot);
 120             clearBase();
 121             clearOffset();
 122             m_getValue = JSC_REGISTER_SLOT_MARKER;
 123             m_data.registerSlot = registerSlot;
 124         }
 125
 126         void setCustom(JSValue slotBase, GetValueFunc getValue)
 127         {
 128             ASSERT(slotBase);
 129             ASSERT(getValue);
 130             m_getValue = getValue;
 131             m_slotBase = slotBase;
 132         }
 133
 134         void setCustomIndex(JSValue slotBase, unsigned index, GetValueFunc getValue)
 135         {
 136             ASSERT(slotBase);
 137             ASSERT(getValue);
 138             m_getValue = getValue;
 139             m_slotBase = slotBase;
 140             m_data.index = index;
 141         }
 142
 143         void setGetterSlot(JSObject* getterFunc)
 144         {
 145             ASSERT(getterFunc);
 146             m_getValue = functionGetter;
 147             m_data.getterFunc = getterFunc;
 148         }
 149
 150         void setUndefined()
 151         {
 152             setValue(jsUndefined());
 153         }
 154
 155         JSValue slotBase() const
 156         {
 157             return m_slotBase;
 158         }
 159
 160         void setBase(JSValue base)
 161         {
 162             ASSERT(m_slotBase);
 163             ASSERT(base);
 164             m_slotBase = base;
 165         }
 166
 167         void clearBase()
 168         {
 169 #ifndef NDEBUG
 170             m_slotBase = JSValue();
 171 #endif
 172         }
 173
 174         void clearValue()
 175         {
 176 #ifndef NDEBUG
 177             m_value = JSValue();
 178 #endif
 179         }
 180
 181         void clearOffset()
 182         {
 183             // Clear offset even in release builds, in case this PropertySlot has been used before.
 184             // (For other data members, we don't need to clear anything because reuse would meaningfully overwrite them.)
 185             m_offset = WTF::notFound;
 186         }
 187
 188         unsigned index() const { return m_data.index; }
 189
 190     private:
 191         static JSValue functionGetter(ExecState*, const Identifier&, const PropertySlot&);
 192
 193         GetValueFunc m_getValue;
 194
 195         JSValue m_slotBase;
 196         union {
 197             JSObject* getterFunc;
 198             JSValue* valueSlot;
 199             Register* registerSlot;
 200             unsigned index;
 201         } m_data;
 202
 203         JSValue m_value;
 204
 205         size_t m_offset;
 206     };
 207
 208 } // namespace JSC
 209
 210 #endif // PropertySlot_h