// Copyright 2010 the V8 project authors. All rights reserved.

// Redistribution and use in source and binary forms, with or without

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

// met:

//

//     * Redistributions of source code must retain the above copyright

//       notice, this list of conditions and the following disclaimer.

//     * Redistributions in binary form must reproduce the above

//       copyright notice, this list of conditions and the following

//       disclaimer in the documentation and/or other materials provided

//       with the distribution.

//     * Neither the name of Google Inc. nor the names of its

//       contributors may be used to endorse or promote products derived

//       from this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR

// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT

// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include <algorithm>

#include <climits>

#include <cmath>

#include "double-to-string.h"

#include "bignum-dtoa.h"

#include "fast-dtoa.h"

#include "fixed-dtoa.h"

#include "ieee.h"

#include "utils.h"

namespace double_conversion {

const DoubleToStringConverter& DoubleToStringConverter::EcmaScriptConverter() {

  int flags = UNIQUE_ZERO | EMIT_POSITIVE_EXPONENT_SIGN;

  static DoubleToStringConverter converter(flags,

                                           "Infinity",

                                           "NaN",

                                           'e',

                                           -6, 21,

                                           6, 0);

  return converter;

}

bool DoubleToStringConverter::HandleSpecialValues(

    double value,

    StringBuilder* result_builder) const {

  Double double_inspect(value);

  if (double_inspect.IsInfinite()) {

    if (infinity_symbol_ == DOUBLE_CONVERSION_NULLPTR) return false;

    if (value < 0) {

      result_builder->AddCharacter('-');

    }

    result_builder->AddString(infinity_symbol_);

    return true;

  }

  if (double_inspect.IsNan()) {

    if (nan_symbol_ == DOUBLE_CONVERSION_NULLPTR) return false;

    result_builder->AddString(nan_symbol_);

    return true;

  }

  return false;

}

void DoubleToStringConverter::CreateExponentialRepresentation(

    const char* decimal_digits,

    int length,

    int exponent,

    StringBuilder* result_builder) const {

  DOUBLE_CONVERSION_ASSERT(length != 0);

  result_builder->AddCharacter(decimal_digits[0]);

  if (length == 1) {

    if ((flags_ & EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL) != 0) {

      result_builder->AddCharacter('.');

      if ((flags_ & EMIT_TRAILING_ZERO_AFTER_POINT_IN_EXPONENTIAL) != 0) {

          result_builder->AddCharacter('0');

      }

    }

  } else {

    result_builder->AddCharacter('.');

    result_builder->AddSubstring(&decimal_digits[1], length-1);

  }

  result_builder->AddCharacter(exponent_character_);

  if (exponent < 0) {

    result_builder->AddCharacter('-');

    exponent = -exponent;

  } else {

    if ((flags_ & EMIT_POSITIVE_EXPONENT_SIGN) != 0) {

      result_builder->AddCharacter('+');

    }

  }

  DOUBLE_CONVERSION_ASSERT(exponent < 1e4);

  // Changing this constant requires updating the comment of DoubleToStringConverter constructor

  const int kMaxExponentLength = 5;

  char buffer[kMaxExponentLength + 1];

  buffer[kMaxExponentLength] = '\0';

  int first_char_pos = kMaxExponentLength;

  if (exponent == 0) {

    buffer[--first_char_pos] = '0';

  } else {

    while (exponent > 0) {

      buffer[--first_char_pos] = '0' + (exponent % 10);

      exponent /= 10;

    }

  }

  // Add prefix '0' to make exponent width >= min(min_exponent_with_, kMaxExponentLength)

  // For example: convert 1e+9 -> 1e+09, if min_exponent_with_ is set to 2

  while(kMaxExponentLength - first_char_pos < std::min(min_exponent_width_, kMaxExponentLength)) {

    buffer[--first_char_pos] = '0';

  }

  result_builder->AddSubstring(&buffer[first_char_pos],

                               kMaxExponentLength - first_char_pos);

}

void DoubleToStringConverter::CreateDecimalRepresentation(

    const char* decimal_digits,

    int length,

    int decimal_point,

    int digits_after_point,

    StringBuilder* result_builder) const {

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

  if (decimal_point <= 0) {

      // "0.00000decimal_rep" or "0.000decimal_rep00".

    result_builder->AddCharacter('0');

    if (digits_after_point > 0) {

      result_builder->AddCharacter('.');

      result_builder->AddPadding('0', -decimal_point);

      DOUBLE_CONVERSION_ASSERT(length <= digits_after_point - (-decimal_point));

      result_builder->AddSubstring(decimal_digits, length);

      int remaining_digits = digits_after_point - (-decimal_point) - length;

      result_builder->AddPadding('0', remaining_digits);

    }

  } else if (decimal_point >= length) {

    // "decimal_rep0000.00000" or "decimal_rep.0000".

    result_builder->AddSubstring(decimal_digits, length);

    result_builder->AddPadding('0', decimal_point - length);

    if (digits_after_point > 0) {

      result_builder->AddCharacter('.');

      result_builder->AddPadding('0', digits_after_point);

    }

  } else {

    // "decima.l_rep000".

    DOUBLE_CONVERSION_ASSERT(digits_after_point > 0);

    result_builder->AddSubstring(decimal_digits, decimal_point);

    result_builder->AddCharacter('.');

    DOUBLE_CONVERSION_ASSERT(length - decimal_point <= digits_after_point);

    result_builder->AddSubstring(&decimal_digits[decimal_point],

                                 length - decimal_point);

    int remaining_digits = digits_after_point - (length - decimal_point);

    result_builder->AddPadding('0', remaining_digits);

  }

  if (digits_after_point == 0) {

    if ((flags_ & EMIT_TRAILING_DECIMAL_POINT) != 0) {

      result_builder->AddCharacter('.');

    }

    if ((flags_ & EMIT_TRAILING_ZERO_AFTER_POINT) != 0) {

      result_builder->AddCharacter('0');

    }

  }

}

bool DoubleToStringConverter::ToShortestIeeeNumber(

    double value,

    StringBuilder* result_builder,

    DoubleToStringConverter::DtoaMode mode) const {

  DOUBLE_CONVERSION_ASSERT(mode == SHORTEST || mode == SHORTEST_SINGLE);

  if (Double(value).IsSpecial()) {

    return HandleSpecialValues(value, result_builder);

  }

  int decimal_point = 0;

  bool sign;

  const int kDecimalRepCapacity = kBase10MaximalLength + 1;

  char decimal_rep[kDecimalRepCapacity];

  int decimal_rep_length;

  DoubleToAscii(value, mode, 0, decimal_rep, kDecimalRepCapacity,

                &sign, &decimal_rep_length, &decimal_point);

  bool unique_zero = (flags_ & UNIQUE_ZERO) != 0;

  if (sign && (value != 0.0 || !unique_zero)) {

    result_builder->AddCharacter('-');

  }

  int exponent = decimal_point - 1;

  if ((decimal_in_shortest_low_ <= exponent) &&

      (exponent < decimal_in_shortest_high_)) {

    CreateDecimalRepresentation(decimal_rep, decimal_rep_length,

                                decimal_point,

                                (std::max)(0, decimal_rep_length - decimal_point),

                                result_builder);

  } else {

    CreateExponentialRepresentation(decimal_rep, decimal_rep_length, exponent,

                                    result_builder);

  }

  return true;

}

bool DoubleToStringConverter::ToFixed(double value,

                                      int requested_digits,

                                      StringBuilder* result_builder) const {

  DOUBLE_CONVERSION_ASSERT(kMaxFixedDigitsBeforePoint == 60);

  const double kFirstNonFixed = 1e60;

  if (Double(value).IsSpecial()) {

    return HandleSpecialValues(value, result_builder);

  }

  if (requested_digits > kMaxFixedDigitsAfterPoint) return false;

  if (value >= kFirstNonFixed || value <= -kFirstNonFixed) return false;

  // Find a sufficiently precise decimal representation of n.

  int decimal_point;

  bool sign;

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

  const int kDecimalRepCapacity =

      kMaxFixedDigitsBeforePoint + kMaxFixedDigitsAfterPoint + 1;

  char decimal_rep[kDecimalRepCapacity];

  int decimal_rep_length;

  DoubleToAscii(value, FIXED, requested_digits,

                decimal_rep, kDecimalRepCapacity,

                &sign, &decimal_rep_length, &decimal_point);

  bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);

  if (sign && (value != 0.0 || !unique_zero)) {

    result_builder->AddCharacter('-');

  }

  CreateDecimalRepresentation(decimal_rep, decimal_rep_length, decimal_point,

                              requested_digits, result_builder);

  return true;

}

bool DoubleToStringConverter::ToExponential(

    double value,

    int requested_digits,

    StringBuilder* result_builder) const {

  if (Double(value).IsSpecial()) {

    return HandleSpecialValues(value, result_builder);

  }

  if (requested_digits < -1) return false;

  if (requested_digits > kMaxExponentialDigits) return false;

  int decimal_point;

  bool sign;

  // Add space for digit before the decimal point and the '\0' character.

  const int kDecimalRepCapacity = kMaxExponentialDigits + 2;

  DOUBLE_CONVERSION_ASSERT(kDecimalRepCapacity > kBase10MaximalLength);

  char decimal_rep[kDecimalRepCapacity];

#ifndef NDEBUG

  // Problem: there is an assert in StringBuilder::AddSubstring() that

  // will pass this buffer to strlen(), and this buffer is not generally

  // null-terminated.

  memset(decimal_rep, 0, sizeof(decimal_rep));

#endif

  int decimal_rep_length;

  if (requested_digits == -1) {

    DoubleToAscii(value, SHORTEST, 0,

                  decimal_rep, kDecimalRepCapacity,

                  &sign, &decimal_rep_length, &decimal_point);

  } else {

    DoubleToAscii(value, PRECISION, requested_digits + 1,

                  decimal_rep, kDecimalRepCapacity,

                  &sign, &decimal_rep_length, &decimal_point);

    DOUBLE_CONVERSION_ASSERT(decimal_rep_length <= requested_digits + 1);

    for (int i = decimal_rep_length; i < requested_digits + 1; ++i) {

      decimal_rep[i] = '0';

    }

    decimal_rep_length = requested_digits + 1;

  }

  bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);

  if (sign && (value != 0.0 || !unique_zero)) {

    result_builder->AddCharacter('-');

  }

  int exponent = decimal_point - 1;

  CreateExponentialRepresentation(decimal_rep,

                                  decimal_rep_length,

                                  exponent,

                                  result_builder);

  return true;

}

bool DoubleToStringConverter::ToPrecision(double value,

                                          int precision,

                                          StringBuilder* result_builder) const {

  if (Double(value).IsSpecial()) {

    return HandleSpecialValues(value, result_builder);

  }

  if (precision < kMinPrecisionDigits || precision > kMaxPrecisionDigits) {

    return false;

  }

  // Find a sufficiently precise decimal representation of n.

  int decimal_point;

  bool sign;

  // Add one for the terminating null character.

  const int kDecimalRepCapacity = kMaxPrecisionDigits + 1;

  char decimal_rep[kDecimalRepCapacity];

  int decimal_rep_length;

  DoubleToAscii(value, PRECISION, precision,

                decimal_rep, kDecimalRepCapacity,

                &sign, &decimal_rep_length, &decimal_point);

  DOUBLE_CONVERSION_ASSERT(decimal_rep_length <= precision);

  bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);

  if (sign && (value != 0.0 || !unique_zero)) {

    result_builder->AddCharacter('-');

  }

  // The exponent if we print the number as x.xxeyyy. That is with the

  // decimal point after the first digit.

  int exponent = decimal_point - 1;

  int extra_zero = ((flags_ & EMIT_TRAILING_ZERO_AFTER_POINT) != 0) ? 1 : 0;

  bool as_exponential =

      (-decimal_point + 1 > max_leading_padding_zeroes_in_precision_mode_) ||

      (decimal_point - precision + extra_zero >

       max_trailing_padding_zeroes_in_precision_mode_);

  if ((flags_ & NO_TRAILING_ZERO) != 0) {

    // Truncate trailing zeros that occur after the decimal point (if exponential,

    // that is everything after the first digit).

    int stop = as_exponential ? 1 : std::max(1, decimal_point);

    while (decimal_rep_length > stop && decimal_rep[decimal_rep_length - 1] == '0') {

      --decimal_rep_length;

    }

    // Clamp precision to avoid the code below re-adding the zeros.

    precision = std::min(precision, decimal_rep_length);

  }

  if (as_exponential) {

    // Fill buffer to contain 'precision' digits.

    // Usually the buffer is already at the correct length, but 'DoubleToAscii'

    // is allowed to return less characters.

    for (int i = decimal_rep_length; i < precision; ++i) {

      decimal_rep[i] = '0';

    }

    CreateExponentialRepresentation(decimal_rep,

                                    precision,

                                    exponent,

                                    result_builder);

  } else {

    CreateDecimalRepresentation(decimal_rep, decimal_rep_length, decimal_point,

                                (std::max)(0, precision - decimal_point),

                                result_builder);

  }

  return true;

}

static BignumDtoaMode DtoaToBignumDtoaMode(

    DoubleToStringConverter::DtoaMode dtoa_mode) {

  switch (dtoa_mode) {

    case DoubleToStringConverter::SHORTEST:  return BIGNUM_DTOA_SHORTEST;

    case DoubleToStringConverter::SHORTEST_SINGLE:

        return BIGNUM_DTOA_SHORTEST_SINGLE;

    case DoubleToStringConverter::FIXED:     return BIGNUM_DTOA_FIXED;

    case DoubleToStringConverter::PRECISION: return BIGNUM_DTOA_PRECISION;

    default:

      DOUBLE_CONVERSION_UNREACHABLE();

  }

}

void DoubleToStringConverter::DoubleToAscii(double v,

                                            DtoaMode mode,

                                            int requested_digits,

                                            char* buffer,

                                            int buffer_length,

                                            bool* sign,

                                            int* length,

                                            int* point) {

  Vector<char> vector(buffer, buffer_length);

  DOUBLE_CONVERSION_ASSERT(!Double(v).IsSpecial());

  DOUBLE_CONVERSION_ASSERT(mode == SHORTEST || mode == SHORTEST_SINGLE || requested_digits >= 0);

  if (Double(v).Sign() < 0) {

    *sign = true;

    v = -v;

  } else {

    *sign = false;

  }

  if (mode == PRECISION && requested_digits == 0) {

    vector[0] = '\0';

    *length = 0;

    *point = 0;

    return;

  }

  if (v == 0) {

    vector[0] = '0';

    vector[1] = '\0';

    *length = 1;

    *point = 1;

    return;

  }

  bool fast_worked;

  switch (mode) {

    case SHORTEST:

      fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST, 0, vector, length, point);

      break;

    case SHORTEST_SINGLE:

      fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST_SINGLE, 0,

                             vector, length, point);

      break;

    case FIXED:

      fast_worked = FastFixedDtoa(v, requested_digits, vector, length, point);

      break;

    case PRECISION:

      fast_worked = FastDtoa(v, FAST_DTOA_PRECISION, requested_digits,

                             vector, length, point);

      break;

    default:

      fast_worked = false;

      DOUBLE_CONVERSION_UNREACHABLE();

  }

  if (fast_worked) return;

  // If the fast dtoa didn't succeed use the slower bignum version.

  BignumDtoaMode bignum_mode = DtoaToBignumDtoaMode(mode);

  BignumDtoa(v, bignum_mode, requested_digits, vector, length, point);

  vector[*length] = '\0';

}

}  // namespace double_conversion