CSE2410 Fall 2014 Bounce

// Copyright 2011 the V8 project authors. All rights reserved.

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// modification, are permitted provided that the following conditions are

// met:

//

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#include <stdarg.h>

#include <limits.h>

#include <cmath>

#include "conversions-inl.h"

#include "dtoa.h"

#include "list-inl.h"

#include "strtod.h"

#include "utils.h"

#ifndef _STLP_VENDOR_CSTD

// STLPort doesn't import fpclassify into the std namespace.

using std::fpclassify;

#endif

namespace v8 {

namespace internal {

double StringToDouble(UnicodeCache* unicode_cache,

                      const char* str, int flags, double empty_string_val) {

  // We cast to const uint8_t* here to avoid instantiating the

  // InternalStringToDouble() template for const char* as well.

  const uint8_t* start = reinterpret_cast<const uint8_t*>(str);

  const uint8_t* end = start + StrLength(str);

  return InternalStringToDouble(unicode_cache, start, end, flags,

                                empty_string_val);

}

double StringToDouble(UnicodeCache* unicode_cache,

                      Vector<const char> str,

                      int flags,

                      double empty_string_val) {

  // We cast to const uint8_t* here to avoid instantiating the

  // InternalStringToDouble() template for const char* as well.

  const uint8_t* start = reinterpret_cast<const uint8_t*>(str.start());

  const uint8_t* end = start + str.length();

  return InternalStringToDouble(unicode_cache, start, end, flags,

                                empty_string_val);

}

double StringToDouble(UnicodeCache* unicode_cache,

                      Vector<const uc16> str,

                      int flags,

                      double empty_string_val) {

  const uc16* end = str.start() + str.length();

  return InternalStringToDouble(unicode_cache, str.start(), end, flags,

                                empty_string_val);

}

const char* DoubleToCString(double v, Vector<char> buffer) {

  switch (fpclassify(v)) {

    case FP_NAN: return "NaN";

    case FP_INFINITE: return (v < 0.0 ? "-Infinity" : "Infinity");

    case FP_ZERO: return "0";

    default: {

      SimpleStringBuilder builder(buffer.start(), buffer.length());

      int decimal_point;

      int sign;

      const int kV8DtoaBufferCapacity = kBase10MaximalLength + 1;

      char decimal_rep[kV8DtoaBufferCapacity];

      int length;

      DoubleToAscii(v, DTOA_SHORTEST, 0,

                    Vector<char>(decimal_rep, kV8DtoaBufferCapacity),

                    &sign, &length, &decimal_point);

      if (sign) builder.AddCharacter('-');

      if (length <= decimal_point && decimal_point <= 21) {

        // ECMA-262 section 9.8.1 step 6.

        builder.AddString(decimal_rep);

        builder.AddPadding('0', decimal_point - length);

      } else if (0 < decimal_point && decimal_point <= 21) {

        // ECMA-262 section 9.8.1 step 7.

        builder.AddSubstring(decimal_rep, decimal_point);

        builder.AddCharacter('.');

        builder.AddString(decimal_rep + decimal_point);

      } else if (decimal_point <= 0 && decimal_point > -6) {

        // ECMA-262 section 9.8.1 step 8.

        builder.AddString("0.");

        builder.AddPadding('0', -decimal_point);

        builder.AddString(decimal_rep);

      } else {

        // ECMA-262 section 9.8.1 step 9 and 10 combined.

        builder.AddCharacter(decimal_rep[0]);

        if (length != 1) {

          builder.AddCharacter('.');

          builder.AddString(decimal_rep + 1);

        }

        builder.AddCharacter('e');

        builder.AddCharacter((decimal_point >= 0) ? '+' : '-');

        int exponent = decimal_point - 1;

        if (exponent < 0) exponent = -exponent;

        builder.AddDecimalInteger(exponent);

      }

    return builder.Finalize();

    }

  }

}

const char* IntToCString(int n, Vector<char> buffer) {

  bool negative = false;

  if (n < 0) {

    // We must not negate the most negative int.

    if (n == kMinInt) return DoubleToCString(n, buffer);

    negative = true;

    n = -n;

  }

  // Build the string backwards from the least significant digit.

  int i = buffer.length();

  buffer[--i] = '\0';

  do {

    buffer[--i] = '0' + (n % 10);

    n /= 10;

  } while (n);

  if (negative) buffer[--i] = '-';

  return buffer.start() + i;

}

char* DoubleToFixedCString(double value, int f) {

  const int kMaxDigitsBeforePoint = 21;

  const double kFirstNonFixed = 1e21;

  const int kMaxDigitsAfterPoint = 20;

  ASSERT(f >= 0);

  ASSERT(f <= kMaxDigitsAfterPoint);

  bool negative = false;

  double abs_value = value;

  if (value < 0) {

    abs_value = -value;

    negative = true;

  }

  // If abs_value has more than kMaxDigitsBeforePoint digits before the point

  // use the non-fixed conversion routine.

  if (abs_value >= kFirstNonFixed) {

    char arr[100];

    Vector<char> buffer(arr, ARRAY_SIZE(arr));

    return StrDup(DoubleToCString(value, buffer));

  }

  // Find a sufficiently precise decimal representation of n.

  int decimal_point;

  int sign;

  // Add space for the '\0' byte.

  const int kDecimalRepCapacity =

      kMaxDigitsBeforePoint + kMaxDigitsAfterPoint + 1;

  char decimal_rep[kDecimalRepCapacity];

  int decimal_rep_length;

  DoubleToAscii(value, DTOA_FIXED, f,

                Vector<char>(decimal_rep, kDecimalRepCapacity),

                &sign, &decimal_rep_length, &decimal_point);

  // Create a representation that is padded with zeros if needed.

  int zero_prefix_length = 0;

  int zero_postfix_length = 0;

  if (decimal_point <= 0) {

    zero_prefix_length = -decimal_point + 1;

    decimal_point = 1;

  }

  if (zero_prefix_length + decimal_rep_length < decimal_point + f) {

    zero_postfix_length = decimal_point + f - decimal_rep_length -

                          zero_prefix_length;

  }

  unsigned rep_length =

      zero_prefix_length + decimal_rep_length + zero_postfix_length;

  SimpleStringBuilder rep_builder(rep_length + 1);

  rep_builder.AddPadding('0', zero_prefix_length);

  rep_builder.AddString(decimal_rep);

  rep_builder.AddPadding('0', zero_postfix_length);

  char* rep = rep_builder.Finalize();

  // Create the result string by appending a minus and putting in a

  // decimal point if needed.

  unsigned result_size = decimal_point + f + 2;

  SimpleStringBuilder builder(result_size + 1);

  if (negative) builder.AddCharacter('-');

  builder.AddSubstring(rep, decimal_point);

  if (f > 0) {

    builder.AddCharacter('.');

    builder.AddSubstring(rep + decimal_point, f);

  }

  DeleteArray(rep);

  return builder.Finalize();

}

static char* CreateExponentialRepresentation(char* decimal_rep,

                                             int exponent,

                                             bool negative,

                                             int significant_digits) {

  bool negative_exponent = false;

  if (exponent < 0) {

    negative_exponent = true;

    exponent = -exponent;

  }

  // Leave room in the result for appending a minus, for a period, the

  // letter 'e', a minus or a plus depending on the exponent, and a

  // three digit exponent.

  unsigned result_size = significant_digits + 7;

  SimpleStringBuilder builder(result_size + 1);

  if (negative) builder.AddCharacter('-');

  builder.AddCharacter(decimal_rep[0]);

  if (significant_digits != 1) {

    builder.AddCharacter('.');

    builder.AddString(decimal_rep + 1);

    int rep_length = StrLength(decimal_rep);

    builder.AddPadding('0', significant_digits - rep_length);

  }

  builder.AddCharacter('e');

  builder.AddCharacter(negative_exponent ? '-' : '+');

  builder.AddDecimalInteger(exponent);

  return builder.Finalize();

}

char* DoubleToExponentialCString(double value, int f) {

  const int kMaxDigitsAfterPoint = 20;

  // f might be -1 to signal that f was undefined in JavaScript.

  ASSERT(f >= -1 && f <= kMaxDigitsAfterPoint);

  bool negative = false;

  if (value < 0) {

    value = -value;

    negative = true;

  }

  // Find a sufficiently precise decimal representation of n.

  int decimal_point;

  int sign;

  // f corresponds to the digits after the point. There is always one digit

  // before the point. The number of requested_digits equals hence f + 1.

  // And we have to add one character for the null-terminator.

  const int kV8DtoaBufferCapacity = kMaxDigitsAfterPoint + 1 + 1;

  // Make sure that the buffer is big enough, even if we fall back to the

  // shortest representation (which happens when f equals -1).

  ASSERT(kBase10MaximalLength <= kMaxDigitsAfterPoint + 1);

  char decimal_rep[kV8DtoaBufferCapacity];

  int decimal_rep_length;

  if (f == -1) {

    DoubleToAscii(value, DTOA_SHORTEST, 0,

                  Vector<char>(decimal_rep, kV8DtoaBufferCapacity),

                  &sign, &decimal_rep_length, &decimal_point);

    f = decimal_rep_length - 1;

  } else {

    DoubleToAscii(value, DTOA_PRECISION, f + 1,

                  Vector<char>(decimal_rep, kV8DtoaBufferCapacity),

                  &sign, &decimal_rep_length, &decimal_point);

  }

  ASSERT(decimal_rep_length > 0);

  ASSERT(decimal_rep_length <= f + 1);

  int exponent = decimal_point - 1;

  char* result =

      CreateExponentialRepresentation(decimal_rep, exponent, negative, f+1);

  return result;

}

char* DoubleToPrecisionCString(double value, int p) {

  const int kMinimalDigits = 1;

  const int kMaximalDigits = 21;

  ASSERT(p >= kMinimalDigits && p <= kMaximalDigits);

  USE(kMinimalDigits);

  bool negative = false;

  if (value < 0) {

    value = -value;

    negative = true;

  }

  // Find a sufficiently precise decimal representation of n.

  int decimal_point;

  int sign;

  // Add one for the terminating null character.

  const int kV8DtoaBufferCapacity = kMaximalDigits + 1;

  char decimal_rep[kV8DtoaBufferCapacity];

  int decimal_rep_length;

  DoubleToAscii(value, DTOA_PRECISION, p,

                Vector<char>(decimal_rep, kV8DtoaBufferCapacity),

                &sign, &decimal_rep_length, &decimal_point);

  ASSERT(decimal_rep_length <= p);

  int exponent = decimal_point - 1;

  char* result = NULL;

  if (exponent < -6 || exponent >= p) {

    result =

        CreateExponentialRepresentation(decimal_rep, exponent, negative, p);

  } else {

    // Use fixed notation.

    //

    // Leave room in the result for appending a minus, a period and in

    // the case where decimal_point is not positive for a zero in

    // front of the period.

    unsigned result_size = (decimal_point <= 0)

        ? -decimal_point + p + 3

        : p + 2;

    SimpleStringBuilder builder(result_size + 1);

    if (negative) builder.AddCharacter('-');

    if (decimal_point <= 0) {

      builder.AddString("0.");

      builder.AddPadding('0', -decimal_point);

      builder.AddString(decimal_rep);

      builder.AddPadding('0', p - decimal_rep_length);

    } else {

      const int m = Min(decimal_rep_length, decimal_point);

      builder.AddSubstring(decimal_rep, m);

      builder.AddPadding('0', decimal_point - decimal_rep_length);

      if (decimal_point < p) {

        builder.AddCharacter('.');

        const int extra = negative ? 2 : 1;

        if (decimal_rep_length > decimal_point) {

          const int len = StrLength(decimal_rep + decimal_point);

          const int n = Min(len, p - (builder.position() - extra));

          builder.AddSubstring(decimal_rep + decimal_point, n);

        }

        builder.AddPadding('0', extra + (p - builder.position()));

      }

    }

    result = builder.Finalize();

  }

  return result;

}

char* DoubleToRadixCString(double value, int radix) {

  ASSERT(radix >= 2 && radix <= 36);

  // Character array used for conversion.

  static const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyz";

  // Buffer for the integer part of the result. 1024 chars is enough

  // for max integer value in radix 2.  We need room for a sign too.

  static const int kBufferSize = 1100;

  char integer_buffer[kBufferSize];

  integer_buffer[kBufferSize - 1] = '\0';

  // Buffer for the decimal part of the result.  We only generate up

  // to kBufferSize - 1 chars for the decimal part.

  char decimal_buffer[kBufferSize];

  decimal_buffer[kBufferSize - 1] = '\0';

  // Make sure the value is positive.

  bool is_negative = value < 0.0;

  if (is_negative) value = -value;

  // Get the integer part and the decimal part.

  double integer_part = floor(value);

  double decimal_part = value - integer_part;

  // Convert the integer part starting from the back.  Always generate

  // at least one digit.

  int integer_pos = kBufferSize - 2;

  do {

    integer_buffer[integer_pos--] =

        chars[static_cast<int>(fmod(integer_part, radix))];

    integer_part /= radix;

  } while (integer_part >= 1.0);

  // Sanity check.

  ASSERT(integer_pos > 0);

  // Add sign if needed.

  if (is_negative) integer_buffer[integer_pos--] = '-';

  // Convert the decimal part.  Repeatedly multiply by the radix to

  // generate the next char.  Never generate more than kBufferSize - 1

  // chars.

  //

  // TODO(1093998): We will often generate a full decimal_buffer of

  // chars because hitting zero will often not happen.  The right

  // solution would be to continue until the string representation can

  // be read back and yield the original value.  To implement this

  // efficiently, we probably have to modify dtoa.

  int decimal_pos = 0;

  while ((decimal_part > 0.0) && (decimal_pos < kBufferSize - 1)) {

    decimal_part *= radix;

    decimal_buffer[decimal_pos++] =

        chars[static_cast<int>(floor(decimal_part))];

    decimal_part -= floor(decimal_part);

  }

  decimal_buffer[decimal_pos] = '\0';

  // Compute the result size.

  int integer_part_size = kBufferSize - 2 - integer_pos;

  // Make room for zero termination.

  unsigned result_size = integer_part_size + decimal_pos;

  // If the number has a decimal part, leave room for the period.

  if (decimal_pos > 0) result_size++;

  // Allocate result and fill in the parts.

  SimpleStringBuilder builder(result_size + 1);

  builder.AddSubstring(integer_buffer + integer_pos + 1, integer_part_size);

  if (decimal_pos > 0) builder.AddCharacter('.');

  builder.AddSubstring(decimal_buffer, decimal_pos);

  return builder.Finalize();

}

} }  // namespace v8::internal