runtime/JSCell.cpp

   1 /*
   2  *  Copyright (C) 1999-2001 Harri Porten (porten@kde.org)
   3  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
   4  *  Copyright (C) 2003, 2007, 2008 Apple Inc. All rights reserved.
   5  *
   6  *  This library is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU Library General Public
   8  *  License as published by the Free Software Foundation; either
   9  *  version 2 of the License, or (at your option) any later version.
  10  *
  11  *  This library is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  *  Library General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU Library General Public License
  17  *  along with this library; see the file COPYING.LIB.  If not, write to
  18  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  19  *  Boston, MA 02110-1301, USA.
  20  *
  21  */
  22
  23 #include "config.h"
  24 #include "JSCell.h"
  25
  26 #include "JSFunction.h"
  27 #include "JSString.h"
  28 #include "JSObject.h"
  29 #include <wtf/MathExtras.h>
  30
  31 namespace JSC {
  32
  33 #if defined NAN && defined INFINITY
  34
  35 extern const double NaN = NAN;
  36 extern const double Inf = INFINITY;
  37
  38 #else // !(defined NAN && defined INFINITY)
  39
  40 // The trick is to define the NaN and Inf globals with a different type than the declaration.
  41 // This trick works because the mangled name of the globals does not include the type, although
  42 // I'm not sure that's guaranteed. There could be alignment issues with this, since arrays of
  43 // characters don't necessarily need the same alignment doubles do, but for now it seems to work.
  44 // It would be good to figure out a 100% clean way that still avoids code that runs at init time.
  45
  46 // Note, we have to use union to ensure alignment. Otherwise, NaN_Bytes can start anywhere,
  47 // while NaN_double has to be 4-byte aligned for 32-bits.
  48 // With -fstrict-aliasing enabled, unions are the only safe way to do type masquerading.
  49
  50 static const union {
  51     struct {
  52         unsigned char NaN_Bytes[8];
  53         unsigned char Inf_Bytes[8];
  54     } bytes;
  55
  56     struct {
  57         double NaN_Double;
  58         double Inf_Double;
  59     } doubles;
  60
  61 } NaNInf = { {
  62 #if PLATFORM(BIG_ENDIAN)
  63     { 0x7f, 0xf8, 0, 0, 0, 0, 0, 0 },
  64     { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 }
  65 #elif PLATFORM(MIDDLE_ENDIAN)
  66     { 0, 0, 0xf8, 0x7f, 0, 0, 0, 0 },
  67     { 0, 0, 0xf0, 0x7f, 0, 0, 0, 0 }
  68 #else
  69     { 0, 0, 0, 0, 0, 0, 0xf8, 0x7f },
  70     { 0, 0, 0, 0, 0, 0, 0xf0, 0x7f }
  71 #endif
  72 } } ;
  73
  74 extern const double NaN = NaNInf.doubles.NaN_Double;
  75 extern const double Inf = NaNInf.doubles.Inf_Double;
  76
  77 #endif // !(defined NAN && defined INFINITY)
  78
  79 void* JSCell::operator new(size_t size, ExecState* exec)
  80 {
  81 #ifdef JAVASCRIPTCORE_BUILDING_ALL_IN_ONE_FILE
  82     return exec->heap()->inlineAllocate(size);
  83 #else
  84     return exec->heap()->allocate(size);
  85 #endif
  86 }
  87
  88 bool JSCell::getUInt32(uint32_t&) const
  89 {
  90     return false;
  91 }
  92
  93 bool JSCell::getString(UString&stringValue) const
  94 {
  95     if (!isString())
  96         return false;
  97     stringValue = static_cast<const JSString*>(this)->value();
  98     return true;
  99 }
 100
 101 UString JSCell::getString() const
 102 {
 103     return isString() ? static_cast<const JSString*>(this)->value() : UString();
 104 }
 105
 106 JSObject* JSCell::getObject()
 107 {
 108     return isObject() ? static_cast<JSObject*>(this) : 0;
 109 }
 110
 111 const JSObject* JSCell::getObject() const
 112 {
 113     return isObject() ? static_cast<const JSObject*>(this) : 0;
 114 }
 115
 116 CallType JSCell::getCallData(CallData&)
 117 {
 118     return CallTypeNone;
 119 }
 120
 121 ConstructType JSCell::getConstructData(ConstructData&)
 122 {
 123     return ConstructTypeNone;
 124 }
 125
 126 bool JSCell::getOwnPropertySlot(ExecState* exec, const Identifier& identifier, PropertySlot& slot)
 127 {
 128     // This is not a general purpose implementation of getOwnPropertySlot.
 129     // It should only be called by JSValue::get.
 130     // It calls getPropertySlot, not getOwnPropertySlot.
 131     JSObject* object = toObject(exec);
 132     slot.setBase(object);
 133     if (!object->getPropertySlot(exec, identifier, slot))
 134         slot.setUndefined();
 135     return true;
 136 }
 137
 138 bool JSCell::getOwnPropertySlot(ExecState* exec, unsigned identifier, PropertySlot& slot)
 139 {
 140     // This is not a general purpose implementation of getOwnPropertySlot.
 141     // It should only be called by JSValue::get.
 142     // It calls getPropertySlot, not getOwnPropertySlot.
 143     JSObject* object = toObject(exec);
 144     slot.setBase(object);
 145     if (!object->getPropertySlot(exec, identifier, slot))
 146         slot.setUndefined();
 147     return true;
 148 }
 149
 150 void JSCell::put(ExecState* exec, const Identifier& identifier, JSValue value, PutPropertySlot& slot)
 151 {
 152     toObject(exec)->put(exec, identifier, value, slot);
 153 }
 154
 155 void JSCell::put(ExecState* exec, unsigned identifier, JSValue value)
 156 {
 157     toObject(exec)->put(exec, identifier, value);
 158 }
 159
 160 bool JSCell::deleteProperty(ExecState* exec, const Identifier& identifier)
 161 {
 162     return toObject(exec)->deleteProperty(exec, identifier);
 163 }
 164
 165 bool JSCell::deleteProperty(ExecState* exec, unsigned identifier)
 166 {
 167     return toObject(exec)->deleteProperty(exec, identifier);
 168 }
 169
 170 JSObject* JSCell::toThisObject(ExecState* exec) const
 171 {
 172     return toObject(exec);
 173 }
 174
 175 UString JSCell::toThisString(ExecState* exec) const
 176 {
 177     return toThisObject(exec)->toString(exec);
 178 }
 179
 180 JSString* JSCell::toThisJSString(ExecState* exec)
 181 {
 182     return jsString(exec, toThisString(exec));
 183 }
 184
 185 const ClassInfo* JSCell::classInfo() const
 186 {
 187     return 0;
 188 }
 189
 190 JSValue JSCell::getJSNumber()
 191 {
 192     return JSValue();
 193 }
 194
 195 bool JSCell::isGetterSetter() const
 196 {
 197     return false;
 198 }
 199
 200 } // namespace JSC