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_MARKER 0
  36 #define INDEX_GETTER_MARKER reinterpret_cast<GetValueFunc>(2)
  37 #define GETTER_FUNCTION_MARKER reinterpret_cast<GetValueFunc>(3)
  38
  39     class PropertySlot {
  40     public:
  41         enum CachedPropertyType {
  42             Uncacheable,
  43             Getter,
  44             Custom,
  45             Value
  46         };
  47
  48         PropertySlot()
  49             : m_cachedPropertyType(Uncacheable)
  50         {
  51             clearBase();
  52             clearOffset();
  53             clearValue();
  54         }
  55
  56         explicit PropertySlot(const JSValue base)
  57             : m_slotBase(base)
  58             , m_cachedPropertyType(Uncacheable)
  59         {
  60             clearOffset();
  61             clearValue();
  62         }
  63
  64         typedef JSValue (*GetValueFunc)(ExecState*, JSValue slotBase, const Identifier&);
  65         typedef JSValue (*GetIndexValueFunc)(ExecState*, JSValue slotBase, unsigned);
  66
  67         JSValue getValue(ExecState* exec, const Identifier& propertyName) const
  68         {
  69             if (m_getValue == JSC_VALUE_MARKER)
  70                 return m_value;
  71             if (m_getValue == INDEX_GETTER_MARKER)
  72                 return m_getIndexValue(exec, slotBase(), index());
  73             if (m_getValue == GETTER_FUNCTION_MARKER)
  74                 return functionGetter(exec);
  75             return m_getValue(exec, slotBase(), propertyName);
  76         }
  77
  78         JSValue getValue(ExecState* exec, unsigned propertyName) const
  79         {
  80             if (m_getValue == JSC_VALUE_MARKER)
  81                 return m_value;
  82             if (m_getValue == INDEX_GETTER_MARKER)
  83                 return m_getIndexValue(exec, m_slotBase, m_data.index);
  84             if (m_getValue == GETTER_FUNCTION_MARKER)
  85                 return functionGetter(exec);
  86             return m_getValue(exec, slotBase(), Identifier::from(exec, propertyName));
  87         }
  88
  89         CachedPropertyType cachedPropertyType() const { return m_cachedPropertyType; }
  90         bool isCacheable() const { return m_cachedPropertyType != Uncacheable; }
  91         bool isCacheableValue() const { return m_cachedPropertyType == Value; }
  92         size_t cachedOffset() const
  93         {
  94             ASSERT(isCacheable());
  95             return m_offset;
  96         }
  97
  98         void setValue(JSValue slotBase, JSValue value)
  99         {
 100             ASSERT(value);
 101             clearOffset();
 102             m_getValue = JSC_VALUE_MARKER;
 103             m_slotBase = slotBase;
 104             m_value = value;
 105         }
 106
 107         void setValue(JSValue slotBase, JSValue value, size_t offset)
 108         {
 109             ASSERT(value);
 110             m_getValue = JSC_VALUE_MARKER;
 111             m_slotBase = slotBase;
 112             m_value = value;
 113             m_offset = offset;
 114             m_cachedPropertyType = Value;
 115         }
 116
 117         void setValue(JSValue value)
 118         {
 119             ASSERT(value);
 120             clearBase();
 121             clearOffset();
 122             m_getValue = JSC_VALUE_MARKER;
 123             m_value = value;
 124         }
 125
 126         void setCustom(JSValue slotBase, GetValueFunc getValue)
 127         {
 128             ASSERT(slotBase);
 129             ASSERT(getValue);
 130             m_getValue = getValue;
 131             m_getIndexValue = 0;
 132             m_slotBase = slotBase;
 133         }
 134
 135         void setCacheableCustom(JSValue slotBase, GetValueFunc getValue)
 136         {
 137             ASSERT(slotBase);
 138             ASSERT(getValue);
 139             m_getValue = getValue;
 140             m_getIndexValue = 0;
 141             m_slotBase = slotBase;
 142             m_cachedPropertyType = Custom;
 143         }
 144
 145         void setCustomIndex(JSValue slotBase, unsigned index, GetIndexValueFunc getIndexValue)
 146         {
 147             ASSERT(slotBase);
 148             ASSERT(getIndexValue);
 149             m_getValue = INDEX_GETTER_MARKER;
 150             m_getIndexValue = getIndexValue;
 151             m_slotBase = slotBase;
 152             m_data.index = index;
 153         }
 154
 155         void setGetterSlot(JSObject* getterFunc)
 156         {
 157             ASSERT(getterFunc);
 158             m_thisValue = m_slotBase;
 159             m_getValue = GETTER_FUNCTION_MARKER;
 160             m_data.getterFunc = getterFunc;
 161         }
 162
 163         void setCacheableGetterSlot(JSValue slotBase, JSObject* getterFunc, unsigned offset)
 164         {
 165             ASSERT(getterFunc);
 166             m_getValue = GETTER_FUNCTION_MARKER;
 167             m_thisValue = m_slotBase;
 168             m_slotBase = slotBase;
 169             m_data.getterFunc = getterFunc;
 170             m_offset = offset;
 171             m_cachedPropertyType = Getter;
 172         }
 173
 174         void setUndefined()
 175         {
 176             setValue(jsUndefined());
 177         }
 178
 179         JSValue slotBase() const
 180         {
 181             return m_slotBase;
 182         }
 183
 184         void setBase(JSValue base)
 185         {
 186             ASSERT(m_slotBase);
 187             ASSERT(base);
 188             m_slotBase = base;
 189         }
 190
 191         void clearBase()
 192         {
 193 #ifndef NDEBUG
 194             m_slotBase = JSValue();
 195 #endif
 196         }
 197
 198         void clearValue()
 199         {
 200 #ifndef NDEBUG
 201             m_value = JSValue();
 202 #endif
 203         }
 204
 205         void clearOffset()
 206         {
 207             // Clear offset even in release builds, in case this PropertySlot has been used before.
 208             // (For other data members, we don't need to clear anything because reuse would meaningfully overwrite them.)
 209             m_offset = 0;
 210             m_cachedPropertyType = Uncacheable;
 211         }
 212
 213         unsigned index() const { return m_data.index; }
 214
 215         GetValueFunc customGetter() const
 216         {
 217             ASSERT(m_cachedPropertyType == Custom);
 218             return m_getValue;
 219         }
 220     private:
 221         JS_EXPORT_PRIVATE JSValue functionGetter(ExecState*) const;
 222
 223         GetValueFunc m_getValue;
 224         GetIndexValueFunc m_getIndexValue;
 225
 226         JSValue m_slotBase;
 227         union {
 228             JSObject* getterFunc;
 229             unsigned index;
 230         } m_data;
 231
 232         JSValue m_value;
 233         JSValue m_thisValue;
 234
 235         size_t m_offset;
 236         CachedPropertyType m_cachedPropertyType;
 237     };
 238
 239 } // namespace JSC
 240
 241 #endif // PropertySlot_h