runtime/JSCJSValue.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, 2012 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 "JSCJSValue.h"
  25
  26 #include "BooleanConstructor.h"
  27 #include "BooleanPrototype.h"
  28 #include "Error.h"
  29 #include "ExceptionHelpers.h"
  30 #include "GetterSetter.h"
  31 #include "JSCJSValueInlines.h"
  32 #include "JSFunction.h"
  33 #include "JSGlobalObject.h"
  34 #include "JSNotAnObject.h"
  35 #include "NumberObject.h"
  36 #include <wtf/MathExtras.h>
  37 #include <wtf/StringExtras.h>
  38
  39 namespace JSC {
  40
  41 static const double D32 = 4294967296.0;
  42
  43 // ECMA 9.4
  44 double JSValue::toInteger(ExecState* exec) const
  45 {
  46     if (isInt32())
  47         return asInt32();
  48     double d = toNumber(exec);
  49     return std::isnan(d) ? 0.0 : trunc(d);
  50 }
  51
  52 double JSValue::toIntegerPreserveNaN(ExecState* exec) const
  53 {
  54     if (isInt32())
  55         return asInt32();
  56     return trunc(toNumber(exec));
  57 }
  58
  59 double JSValue::toNumberSlowCase(ExecState* exec) const
  60 {
  61     ASSERT(!isInt32() && !isDouble());
  62     if (isCell())
  63         return asCell()->toNumber(exec);
  64     if (isTrue())
  65         return 1.0;
  66     return isUndefined() ? QNaN : 0; // null and false both convert to 0.
  67 }
  68
  69 JSObject* JSValue::toObjectSlowCase(ExecState* exec, JSGlobalObject* globalObject) const
  70 {
  71     ASSERT(!isCell());
  72
  73     if (isInt32() || isDouble())
  74         return constructNumber(exec, globalObject, asValue());
  75     if (isTrue() || isFalse())
  76         return constructBooleanFromImmediateBoolean(exec, globalObject, asValue());
  77
  78     ASSERT(isUndefinedOrNull());
  79     throwError(exec, createNotAnObjectError(exec, *this));
  80     return JSNotAnObject::create(exec);
  81 }
  82
  83 JSObject* JSValue::toThisObjectSlowCase(ExecState* exec) const
  84 {
  85     ASSERT(!isCell());
  86
  87     if (isInt32() || isDouble())
  88         return constructNumber(exec, exec->lexicalGlobalObject(), asValue());
  89     if (isTrue() || isFalse())
  90         return constructBooleanFromImmediateBoolean(exec, exec->lexicalGlobalObject(), asValue());
  91     ASSERT(isUndefinedOrNull());
  92     return exec->globalThisValue();
  93 }
  94
  95 JSObject* JSValue::synthesizePrototype(ExecState* exec) const
  96 {
  97     if (isCell()) {
  98         ASSERT(isString());
  99         return exec->lexicalGlobalObject()->stringPrototype();
 100     }
 101
 102     if (isNumber())
 103         return exec->lexicalGlobalObject()->numberPrototype();
 104     if (isBoolean())
 105         return exec->lexicalGlobalObject()->booleanPrototype();
 106
 107     ASSERT(isUndefinedOrNull());
 108     throwError(exec, createNotAnObjectError(exec, *this));
 109     return JSNotAnObject::create(exec);
 110 }
 111
 112 // ECMA 8.7.2
 113 void JSValue::putToPrimitive(ExecState* exec, PropertyName propertyName, JSValue value, PutPropertySlot& slot)
 114 {
 115     VM& vm = exec->vm();
 116
 117     unsigned index = propertyName.asIndex();
 118     if (index != PropertyName::NotAnIndex) {
 119         putToPrimitiveByIndex(exec, index, value, slot.isStrictMode());
 120         return;
 121     }
 122
 123     // Check if there are any setters or getters in the prototype chain
 124     JSObject* obj = synthesizePrototype(exec);
 125     JSValue prototype;
 126     if (propertyName != exec->propertyNames().underscoreProto) {
 127         for (; !obj->structure()->hasReadOnlyOrGetterSetterPropertiesExcludingProto(); obj = asObject(prototype)) {
 128             prototype = obj->prototype();
 129             if (prototype.isNull()) {
 130                 if (slot.isStrictMode())
 131                     throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
 132                 return;
 133             }
 134         }
 135     }
 136
 137     for (; ; obj = asObject(prototype)) {
 138         unsigned attributes;
 139         JSCell* specificValue;
 140         PropertyOffset offset = obj->structure()->get(vm, propertyName, attributes, specificValue);
 141         if (offset != invalidOffset) {
 142             if (attributes & ReadOnly) {
 143                 if (slot.isStrictMode())
 144                     throwError(exec, createTypeError(exec, StrictModeReadonlyPropertyWriteError));
 145                 return;
 146             }
 147
 148             JSValue gs = obj->getDirect(offset);
 149             if (gs.isGetterSetter()) {
 150                 JSObject* setterFunc = asGetterSetter(gs)->setter();
 151                 if (!setterFunc) {
 152                     if (slot.isStrictMode())
 153                         throwError(exec, createTypeError(exec, ASCIILiteral("setting a property that has only a getter")));
 154                     return;
 155                 }
 156
 157                 CallData callData;
 158                 CallType callType = setterFunc->methodTable()->getCallData(setterFunc, callData);
 159                 MarkedArgumentBuffer args;
 160                 args.append(value);
 161
 162                 // If this is WebCore's global object then we need to substitute the shell.
 163                 call(exec, setterFunc, callType, callData, *this, args);
 164                 return;
 165             }
 166
 167             // If there's an existing property on the object or one of its
 168             // prototypes it should be replaced, so break here.
 169             break;
 170         }
 171
 172         prototype = obj->prototype();
 173         if (prototype.isNull())
 174             break;
 175     }
 176
 177     if (slot.isStrictMode())
 178         throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
 179     return;
 180 }
 181
 182 void JSValue::putToPrimitiveByIndex(ExecState* exec, unsigned propertyName, JSValue value, bool shouldThrow)
 183 {
 184     if (propertyName > MAX_ARRAY_INDEX) {
 185         PutPropertySlot slot(shouldThrow);
 186         putToPrimitive(exec, Identifier::from(exec, propertyName), value, slot);
 187         return;
 188     }
 189
 190     if (synthesizePrototype(exec)->attemptToInterceptPutByIndexOnHoleForPrototype(exec, *this, propertyName, value, shouldThrow))
 191         return;
 192
 193     if (shouldThrow)
 194         throwTypeError(exec, StrictModeReadonlyPropertyWriteError);
 195 }
 196
 197 void JSValue::dump(PrintStream& out) const
 198 {
 199     if (!*this)
 200         out.print("<JSValue()>");
 201     else if (isInt32())
 202         out.printf("Int32: %d", asInt32());
 203     else if (isDouble()) {
 204 #if USE(JSVALUE64)
 205         out.printf("Double: %lld, %lf", (long long)reinterpretDoubleToInt64(asDouble()), asDouble());
 206 #else
 207         union {
 208             double asDouble;
 209             uint32_t asTwoInt32s[2];
 210         } u;
 211         u.asDouble = asDouble();
 212         out.printf("Double: %08x:%08x, %lf", u.asTwoInt32s[1], u.asTwoInt32s[0], asDouble());
 213 #endif
 214     } else if (isCell()) {
 215         if (asCell()->inherits(&JSString::s_info)) {
 216             JSString* string = jsCast<JSString*>(asCell());
 217             out.print("String: ");
 218             if (string->isRope())
 219                 out.print("(rope) ");
 220             out.print(string->tryGetValue());
 221         } else if (asCell()->inherits(&Structure::s_info)) {
 222             Structure* structure = jsCast<Structure*>(asCell());
 223             out.print(
 224                 "Structure: ", RawPointer(structure), ": ", structure->classInfo()->className,
 225                 ", ", IndexingTypeDump(structure->indexingTypeIncludingHistory()));
 226         } else {
 227             out.print("Cell: ", RawPointer(asCell()));
 228             if (isObject() && asObject(*this)->butterfly())
 229                 out.print("->", RawPointer(asObject(*this)->butterfly()));
 230             out.print(
 231                 " (", RawPointer(asCell()->structure()), ": ", asCell()->structure()->classInfo()->className,
 232                 ", ", IndexingTypeDump(asCell()->structure()->indexingTypeIncludingHistory()), ")");
 233         }
 234     } else if (isTrue())
 235         out.print("True");
 236     else if (isFalse())
 237         out.print("False");
 238     else if (isNull())
 239         out.print("Null");
 240     else if (isUndefined())
 241         out.print("Undefined");
 242     else
 243         out.print("INVALID");
 244 }
 245
 246 // This in the ToInt32 operation is defined in section 9.5 of the ECMA-262 spec.
 247 // Note that this operation is identical to ToUInt32 other than to interpretation
 248 // of the resulting bit-pattern (as such this metod is also called to implement
 249 // ToUInt32).
 250 //
 251 // The operation can be descibed as round towards zero, then select the 32 least
 252 // bits of the resulting value in 2s-complement representation.
 253 int32_t toInt32(double number)
 254 {
 255     int64_t bits = WTF::bitwise_cast<int64_t>(number);
 256     int32_t exp = (static_cast<int32_t>(bits >> 52) & 0x7ff) - 0x3ff;
 257
 258     // If exponent < 0 there will be no bits to the left of the decimal point
 259     // after rounding; if the exponent is > 83 then no bits of precision can be
 260     // left in the low 32-bit range of the result (IEEE-754 doubles have 52 bits
 261     // of fractional precision).
 262     // Note this case handles 0, -0, and all infinte, NaN, & denormal value.
 263     if (exp < 0 || exp > 83)
 264         return 0;
 265
 266     // Select the appropriate 32-bits from the floating point mantissa.  If the
 267     // exponent is 52 then the bits we need to select are already aligned to the
 268     // lowest bits of the 64-bit integer representation of tghe number, no need
 269     // to shift.  If the exponent is greater than 52 we need to shift the value
 270     // left by (exp - 52), if the value is less than 52 we need to shift right
 271     // accordingly.
 272     int32_t result = (exp > 52)
 273         ? static_cast<int32_t>(bits << (exp - 52))
 274         : static_cast<int32_t>(bits >> (52 - exp));
 275
 276     // IEEE-754 double precision values are stored omitting an implicit 1 before
 277     // the decimal point; we need to reinsert this now.  We may also the shifted
 278     // invalid bits into the result that are not a part of the mantissa (the sign
 279     // and exponent bits from the floatingpoint representation); mask these out.
 280     if (exp < 32) {
 281         int32_t missingOne = 1 << exp;
 282         result &= missingOne - 1;
 283         result += missingOne;
 284     }
 285
 286     // If the input value was negative (we could test either 'number' or 'bits',
 287     // but testing 'bits' is likely faster) invert the result appropriately.
 288     return bits < 0 ? -result : result;
 289 }
 290
 291 bool JSValue::isValidCallee()
 292 {
 293     return asObject(asCell())->globalObject();
 294 }
 295
 296 JSString* JSValue::toStringSlowCase(ExecState* exec) const
 297 {
 298     VM& vm = exec->vm();
 299     ASSERT(!isString());
 300     if (isInt32())
 301         return jsString(&vm, vm.numericStrings.add(asInt32()));
 302     if (isDouble())
 303         return jsString(&vm, vm.numericStrings.add(asDouble()));
 304     if (isTrue())
 305         return vm.smallStrings.trueString();
 306     if (isFalse())
 307         return vm.smallStrings.falseString();
 308     if (isNull())
 309         return vm.smallStrings.nullString();
 310     if (isUndefined())
 311         return vm.smallStrings.undefinedString();
 312
 313     ASSERT(isCell());
 314     JSValue value = asCell()->toPrimitive(exec, PreferString);
 315     if (exec->hadException())
 316         return jsEmptyString(exec);
 317     ASSERT(!value.isObject());
 318     return value.toString(exec);
 319 }
 320
 321 String JSValue::toWTFStringSlowCase(ExecState* exec) const
 322 {
 323     return inlineJSValueNotStringtoString(*this, exec);
 324 }
 325
 326 } // namespace JSC