JavaScriptCore/kjs/number_object.cpp

// -*- c-basic-offset: 2 -*-
/*
 *  Copyright (C) 1999-2000,2003 Harri Porten (porten@kde.org)
 *  Copyright (C) 2007 Apple Inc. All rights reserved.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#include "config.h"
#include "number_object.h"
#include "number_object.lut.h"

#include "dtoa.h"
#include "error_object.h"
#include "operations.h"
#include <wtf/MathExtras.h>
#include <wtf/Vector.h>

using namespace KJS;

// ------------------------------ NumberInstance ----------------------------

const ClassInfo NumberInstance::info = {"Number", 0, 0, 0};

NumberInstance::NumberInstance(JSObject *proto)
  : JSWrapperObject(proto)
{
}
// ------------------------------ NumberPrototype ---------------------------

// ECMA 15.7.4

NumberPrototype::NumberPrototype(ExecState *exec,
                                       ObjectPrototype *objProto,
                                       FunctionPrototype *funcProto)
  : NumberInstance(objProto)
{
  setInternalValue(jsNumber(0));

  // The constructor will be added later, after NumberObjectImp has been constructed

  putDirectFunction(new NumberProtoFunc(exec, funcProto, NumberProtoFunc::ToString,       1, exec->propertyNames().toString), DontEnum);
  putDirectFunction(new NumberProtoFunc(exec, funcProto, NumberProtoFunc::ToLocaleString, 0, exec->propertyNames().toLocaleString), DontEnum);
  putDirectFunction(new NumberProtoFunc(exec, funcProto, NumberProtoFunc::ValueOf,        0, exec->propertyNames().valueOf), DontEnum);
  putDirectFunction(new NumberProtoFunc(exec, funcProto, NumberProtoFunc::ToFixed,        1, exec->propertyNames().toFixed), DontEnum);
  putDirectFunction(new NumberProtoFunc(exec, funcProto, NumberProtoFunc::ToExponential,  1, exec->propertyNames().toExponential), DontEnum);
  putDirectFunction(new NumberProtoFunc(exec, funcProto, NumberProtoFunc::ToPrecision,    1, exec->propertyNames().toPrecision), DontEnum);
}


// ------------------------------ NumberProtoFunc ---------------------------

NumberProtoFunc::NumberProtoFunc(ExecState* exec, FunctionPrototype* funcProto, int i, int len, const Identifier& name)
   : InternalFunctionImp(funcProto, name)
   , id(i)
{
  putDirect(exec->propertyNames().length, len, DontDelete|ReadOnly|DontEnum);
}

static UString integer_part_noexp(double d)
{
    int decimalPoint;
    int sign;
    char *result = kjs_dtoa(d, 0, 0, &decimalPoint, &sign, NULL);
    size_t length = strlen(result);
    
    UString str = sign ? "-" : "";
    if (decimalPoint == 9999) {
        str += UString(result);
    } else if (decimalPoint <= 0) {
        str += UString("0");
    } else {
        Vector<char, 1024> buf(decimalPoint + 1);
        
        if (static_cast<int>(length) <= decimalPoint) {
            strcpy(buf.data(), result);
            memset(buf.data() + length, '0', decimalPoint - length);
        } else
            strncpy(buf.data(), result, decimalPoint);
        
        buf[decimalPoint] = '\0';
        str += UString(buf.data());
    }
    
    kjs_freedtoa(result);
    
    return str;
}

static UString char_sequence(char c, int count)
{
    Vector<char, 2048> buf(count + 1, c);
    buf[count] = '\0';

    return UString(buf.data());
}

static double intPow10(int e)
{
  // This function uses the "exponentiation by squaring" algorithm and
  // long double to quickly and precisely calculate integer powers of 10.0.

  // This is a handy workaround for <rdar://problem/4494756>

  if (e == 0)
    return 1.0;

  bool negative = e < 0;
  unsigned exp = negative ? -e : e;

  long double result = 10.0;
  bool foundOne = false;
  for (int bit = 31; bit >= 0; bit--) {
    if (!foundOne) {
      if ((exp >> bit) & 1)
        foundOne = true;
    } else {
      result = result * result;
      if ((exp >> bit) & 1)
        result = result * 10.0;
    }
  }

  if (negative)
    return static_cast<double>(1.0 / result);
  return static_cast<double>(result);
}

// ECMA 15.7.4.2 - 15.7.4.7
JSValue *NumberProtoFunc::callAsFunction(ExecState *exec, JSObject *thisObj, const List &args)
{
  // no generic function. "this" has to be a Number object
  if (!thisObj->inherits(&NumberInstance::info))
    return throwError(exec, TypeError);

  JSValue *v = static_cast<NumberInstance*>(thisObj)->internalValue();
  switch (id) {
  case ToString: {
    double dradix = 10;
    if (!args.isEmpty())
      dradix = args[0]->toInteger(exec);
    if (dradix >= 2 && dradix <= 36 && dradix != 10) { // false for NaN
      int radix = static_cast<int>(dradix);
      const char digits[] = "0123456789abcdefghijklmnopqrstuvwxyz";
      // INT_MAX results in 1024 characters left of the dot with radix 2
      // give the same space on the right side. safety checks are in place
      // unless someone finds a precise rule.
      char s[2048 + 3];
      double x = v->toNumber(exec);
      if (isNaN(x) || isInf(x))
        return jsString(UString::from(x));

      // apply algorithm on absolute value. add sign later.
      bool neg = false;
      if (x < 0.0) {
        neg = true;
        x = -x;
      }
      // convert integer portion
      double f = floor(x);
      double d = f;
      char *dot = s + sizeof(s) / 2;
      char *p = dot;
      *p = '\0';
      do {
        *--p = digits[static_cast<int>(fmod(d, radix))];
        d /= radix;
      } while ((d <= -1.0 || d >= 1.0) && p > s);
      // any decimal fraction ?
      d = x - f;
      const double eps = 0.001; // TODO: guessed. base on radix ?
      if (d < -eps || d > eps) {
        *dot++ = '.';
        do {
          d *= radix;
          *dot++ = digits[static_cast<int>(d)];
          d -= static_cast<int>(d);
        } while ((d < -eps || d > eps) && dot - s < static_cast<int>(sizeof(s)) - 1);
        *dot = '\0';
      }
      // add sign if negative
      if (neg)
        *--p = '-';
      return jsString(p);
    } else
      return jsString(v->toString(exec));
  }
  case ToLocaleString: /* TODO */
    return jsString(v->toString(exec));
  case ValueOf:
    return jsNumber(v->toNumber(exec));
  case ToFixed: 
  {
      JSValue *fractionDigits = args[0];
      double df = fractionDigits->toInteger(exec);
      if (fractionDigits->isUndefined())
            df = 0;
      if (!(df >= 0 && df <= 20)) // true for NaN
          return throwError(exec, RangeError, "toFixed() digits argument must be between 0 and 20");
      int f = (int)df;
      
      double x = v->toNumber(exec);
      if (isNaN(x))
          return jsString("NaN");
      
      UString s = "";
      if (x < 0) {
          s += "-";
          x = -x;
      }
      
      if (x >= pow(10.0, 21.0))
          return jsString(s+UString::from(x));
      
      double n = floor(x*pow(10.0, f));
      if (fabs(n / pow(10.0, f) - x) >= fabs((n + 1) / pow(10.0, f) - x))
          n++;
      
      UString m = integer_part_noexp(n);
      
      int k = m.size();
      if (k <= f) {
          UString z = "";
          for (int i = 0; i < f+1-k; i++)
              z += "0";
          m = z + m;
          k = f + 1;
          assert(k == m.size());
      }
      if (k-f < m.size())
          return jsString(s+m.substr(0,k-f)+"."+m.substr(k-f));
      else
          return jsString(s+m.substr(0,k-f));
  }
  case ToExponential: {
      double x = v->toNumber(exec);
      
      if (isNaN(x) || isInf(x))
          return jsString(UString::from(x));
      
      JSValue *fractionDigits = args[0];
      double df = fractionDigits->toInteger(exec);
      if (!fractionDigits->isUndefined() && !(df >= 0 && df <= 20)) // true for NaN
          return throwError(exec, RangeError, "toExponential() argument must between 0 and 20");
      int f = (int)df;
      
      int decimalAdjust = 0;
      if (!fractionDigits->isUndefined()) {
          double logx = floor(log10(fabs(x)));
          x /= pow(10.0, logx);
          double fx = floor(x * pow(10.0, f)) / pow(10.0, f);
          double cx = ceil(x * pow(10.0, f)) / pow(10.0, f);
          
          if (fabs(fx-x) < fabs(cx-x))
              x = fx;
          else
              x = cx;
          
          decimalAdjust = static_cast<int>(logx);
      }
      
      char buf[80];
      int decimalPoint;
      int sign;
      
      if (isNaN(x))
          return jsString("NaN");
      
      char *result = kjs_dtoa(x, 0, 0, &decimalPoint, &sign, NULL);
      size_t length = strlen(result);
      decimalPoint += decimalAdjust;
      
      int i = 0;
      if (sign) {
          buf[i++] = '-';
      }
      
      if (decimalPoint == 999) {
          strcpy(buf + i, result);
      } else {
          buf[i++] = result[0];
          
          if (fractionDigits->isUndefined())
              f = static_cast<int>(length) - 1;
          
          if (length > 1 && f > 0) {
              buf[i++] = '.';
              int haveFDigits = static_cast<int>(length) - 1;
              if (f < haveFDigits) {
                  strncpy(buf+i,result+1, f);
                  i += f;
              }
              else {
                  strcpy(buf+i,result+1);
                  i += static_cast<int>(length) - 1;
                  for (int j = 0; j < f-haveFDigits; j++)
                      buf[i++] = '0';
              }
          }
          
          buf[i++] = 'e';
          buf[i++] = (decimalPoint >= 0) ? '+' : '-';
          // decimalPoint can't be more than 3 digits decimal given the
          // nature of float representation
          int exponential = decimalPoint - 1;
          if (exponential < 0) {
              exponential = exponential * -1;
          }
          if (exponential >= 100) {
              buf[i++] = static_cast<char>('0' + exponential / 100);
          }
          if (exponential >= 10) {
              buf[i++] = static_cast<char>('0' + (exponential % 100) / 10);
          }
          buf[i++] = static_cast<char>('0' + exponential % 10);
          buf[i++] = '\0';
      }
      
      assert(i <= 80);
      
      kjs_freedtoa(result);
      
      return jsString(buf);
  }
  case ToPrecision:
  {
      int e = 0;
      UString m;
      
      double dp = args[0]->toInteger(exec);
      double x = v->toNumber(exec);
      if (isNaN(dp) || isNaN(x) || isInf(x))
          return jsString(v->toString(exec));
      
      UString s = "";
      if (x < 0) {
          s = "-";
          x = -x;
      }
      
      if (!(dp >= 1 && dp <= 21)) // true for NaN
          return throwError(exec, RangeError, "toPrecision() argument must be between 1 and 21");
      int p = (int)dp;
      
      if (x != 0) {
          e = static_cast<int>(log10(x));
          double tens = intPow10(e - p + 1);
          double n = floor(x / tens);
          if (n < intPow10(p - 1)) {
              e = e - 1;
              tens = intPow10(e - p + 1);
              n = floor(x / tens);
          }
          
          if (fabs((n + 1.0) * tens - x) <= fabs(n * tens - x))
            ++n;
          assert(intPow10(p - 1) <= n);
          assert(n < intPow10(p));
          
          m = integer_part_noexp(n);
          if (e < -6 || e >= p) {
              if (m.size() > 1)
                  m = m.substr(0,1)+"."+m.substr(1);
              if (e >= 0)
                  return jsString(s+m+"e+"+UString::from(e));
              else
                  return jsString(s+m+"e-"+UString::from(-e));
          }
      }
      else {
          m = char_sequence('0',p);
          e = 0;
      }
      
      if (e == p-1) {
          return jsString(s+m);
      }
      else if (e >= 0) {
          if (e+1 < m.size())
              return jsString(s+m.substr(0,e+1)+"."+m.substr(e+1));
          else
              return jsString(s+m.substr(0,e+1));
      }
      else {
          return jsString(s+"0."+char_sequence('0',-(e+1))+m);
      }
   }
      
 }
  return NULL;
}

// ------------------------------ NumberObjectImp ------------------------------

const ClassInfo NumberObjectImp::info = {"Function", &InternalFunctionImp::info, &numberTable, 0};

/* Source for number_object.lut.h
@begin numberTable 5
  NaN                   NumberObjectImp::NaNValue       DontEnum|DontDelete|ReadOnly
  NEGATIVE_INFINITY     NumberObjectImp::NegInfinity    DontEnum|DontDelete|ReadOnly
  POSITIVE_INFINITY     NumberObjectImp::PosInfinity    DontEnum|DontDelete|ReadOnly
  MAX_VALUE             NumberObjectImp::MaxValue       DontEnum|DontDelete|ReadOnly
  MIN_VALUE             NumberObjectImp::MinValue       DontEnum|DontDelete|ReadOnly
@end
*/
NumberObjectImp::NumberObjectImp(ExecState* exec, FunctionPrototype* funcProto, NumberPrototype* numberProto)
  : InternalFunctionImp(funcProto)
{
  // Number.Prototype
  putDirect(exec->propertyNames().prototype, numberProto,DontEnum|DontDelete|ReadOnly);

  // no. of arguments for constructor
  putDirect(exec->propertyNames().length, jsNumber(1), ReadOnly|DontDelete|DontEnum);
}

bool NumberObjectImp::getOwnPropertySlot(ExecState* exec, const Identifier& propertyName, PropertySlot& slot)
{
  return getStaticValueSlot<NumberObjectImp, InternalFunctionImp>(exec, &numberTable, this, propertyName, slot);
}

JSValue *NumberObjectImp::getValueProperty(ExecState *, int token) const
{
  // ECMA 15.7.3
  switch(token) {
  case NaNValue:
    return jsNaN();
  case NegInfinity:
    return jsNumber(-Inf);
  case PosInfinity:
    return jsNumber(Inf);
  case MaxValue:
    return jsNumber(1.7976931348623157E+308);
  case MinValue:
    return jsNumber(5E-324);
  }
  return jsNull();
}

bool NumberObjectImp::implementsConstruct() const
{
  return true;
}


// ECMA 15.7.1
JSObject *NumberObjectImp::construct(ExecState *exec, const List &args)
{
  JSObject *proto = exec->lexicalInterpreter()->builtinNumberPrototype();
  NumberInstance *obj(new NumberInstance(proto));

  double n;
  if (args.isEmpty())
    n = 0;
  else
    n = args[0]->toNumber(exec);

  obj->setInternalValue(jsNumber(n));

  return obj;
}

// ECMA 15.7.2
JSValue *NumberObjectImp::callAsFunction(ExecState *exec, JSObject* /*thisObj*/, const List &args)
{
  if (args.isEmpty())
    return jsNumber(0);
  else
    return jsNumber(args[0]->toNumber(exec));
}