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 CPU(BIG_ENDIAN)
  63     { 0x7f, 0xf8, 0, 0, 0, 0, 0, 0 },
  64     { 0x7f, 0xf0, 0, 0, 0, 0, 0, 0 }
  65 #elif CPU(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 bool JSCell::getUInt32(uint32_t&) const
  80 {
  81     return false;
  82 }
  83
  84 bool JSCell::getString(ExecState* exec, UString&stringValue) const
  85 {
  86     if (!isString())
  87         return false;
  88     stringValue = static_cast<const JSString*>(this)->value(exec);
  89     return true;
  90 }
  91
  92 UString JSCell::getString(ExecState* exec) const
  93 {
  94     return isString() ? static_cast<const JSString*>(this)->value(exec) : UString();
  95 }
  96
  97 JSObject* JSCell::getObject()
  98 {
  99     return isObject() ? asObject(this) : 0;
 100 }
 101
 102 const JSObject* JSCell::getObject() const
 103 {
 104     return isObject() ? static_cast<const JSObject*>(this) : 0;
 105 }
 106
 107 CallType JSCell::getCallData(CallData&)
 108 {
 109     return CallTypeNone;
 110 }
 111
 112 ConstructType JSCell::getConstructData(ConstructData&)
 113 {
 114     return ConstructTypeNone;
 115 }
 116
 117 bool JSCell::getOwnPropertySlot(ExecState* exec, const Identifier& identifier, PropertySlot& slot)
 118 {
 119     // This is not a general purpose implementation of getOwnPropertySlot.
 120     // It should only be called by JSValue::get.
 121     // It calls getPropertySlot, not getOwnPropertySlot.
 122     JSObject* object = toObject(exec);
 123     slot.setBase(object);
 124     if (!object->getPropertySlot(exec, identifier, slot))
 125         slot.setUndefined();
 126     return true;
 127 }
 128
 129 bool JSCell::getOwnPropertySlot(ExecState* exec, unsigned identifier, PropertySlot& slot)
 130 {
 131     // This is not a general purpose implementation of getOwnPropertySlot.
 132     // It should only be called by JSValue::get.
 133     // It calls getPropertySlot, not getOwnPropertySlot.
 134     JSObject* object = toObject(exec);
 135     slot.setBase(object);
 136     if (!object->getPropertySlot(exec, identifier, slot))
 137         slot.setUndefined();
 138     return true;
 139 }
 140
 141 void JSCell::put(ExecState* exec, const Identifier& identifier, JSValue value, PutPropertySlot& slot)
 142 {
 143     toObject(exec)->put(exec, identifier, value, slot);
 144 }
 145
 146 void JSCell::put(ExecState* exec, unsigned identifier, JSValue value)
 147 {
 148     toObject(exec)->put(exec, identifier, value);
 149 }
 150
 151 bool JSCell::deleteProperty(ExecState* exec, const Identifier& identifier)
 152 {
 153     return toObject(exec)->deleteProperty(exec, identifier);
 154 }
 155
 156 bool JSCell::deleteProperty(ExecState* exec, unsigned identifier)
 157 {
 158     return toObject(exec)->deleteProperty(exec, identifier);
 159 }
 160
 161 JSObject* JSCell::toThisObject(ExecState* exec) const
 162 {
 163     return toObject(exec);
 164 }
 165
 166 const ClassInfo* JSCell::classInfo() const
 167 {
 168     return 0;
 169 }
 170
 171 JSValue JSCell::getJSNumber()
 172 {
 173     return JSValue();
 174 }
 175
 176 bool JSCell::isGetterSetter() const
 177 {
 178     return false;
 179 }
 180
 181 JSValue JSCell::toPrimitive(ExecState*, PreferredPrimitiveType) const
 182 {
 183     ASSERT_NOT_REACHED();
 184     return JSValue();
 185 }
 186
 187 bool JSCell::getPrimitiveNumber(ExecState*, double&, JSValue&)
 188 {
 189     ASSERT_NOT_REACHED();
 190     return false;
 191 }
 192
 193 bool JSCell::toBoolean(ExecState*) const
 194 {
 195     ASSERT_NOT_REACHED();
 196     return false;
 197 }
 198
 199 double JSCell::toNumber(ExecState*) const
 200 {
 201     ASSERT_NOT_REACHED();
 202     return 0;
 203 }
 204
 205 UString JSCell::toString(ExecState*) const
 206 {
 207     ASSERT_NOT_REACHED();
 208     return UString();
 209 }
 210
 211 JSObject* JSCell::toObject(ExecState*) const
 212 {
 213     ASSERT_NOT_REACHED();
 214     return 0;
 215 }
 216
 217 } // namespace JSC