// Copyright 2012 the V8 project authors. All rights reserved.

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#ifndef DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_

#define DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_

#include "utils.h"

namespace double_conversion {

class DoubleToStringConverter {

 public:

  // When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint

  // or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the

  // function returns false.

  static const int kMaxFixedDigitsBeforePoint = 60;

  static const int kMaxFixedDigitsAfterPoint = 100;

  // When calling ToExponential with a requested_digits

  // parameter > kMaxExponentialDigits then the function returns false.

  static const int kMaxExponentialDigits = 120;

  // When calling ToPrecision with a requested_digits

  // parameter < kMinPrecisionDigits or requested_digits > kMaxPrecisionDigits

  // then the function returns false.

  static const int kMinPrecisionDigits = 1;

  static const int kMaxPrecisionDigits = 120;

  // The maximal number of digits that are needed to emit a double in base 10.

  // A higher precision can be achieved by using more digits, but the shortest

  // accurate representation of any double will never use more digits than

  // kBase10MaximalLength.

  // Note that DoubleToAscii null-terminates its input. So the given buffer

  // should be at least kBase10MaximalLength + 1 characters long.

  static const int kBase10MaximalLength = 17;

  // The maximal number of digits that are needed to emit a single in base 10.

  // A higher precision can be achieved by using more digits, but the shortest

  // accurate representation of any single will never use more digits than

  // kBase10MaximalLengthSingle.

  static const int kBase10MaximalLengthSingle = 9;

  // The length of the longest string that 'ToShortest' can produce when the

  // converter is instantiated with EcmaScript defaults (see

  // 'EcmaScriptConverter')

  // This value does not include the trailing '\0' character.

  // This amount of characters is needed for negative values that hit the

  // 'decimal_in_shortest_low' limit. For example: "-0.0000033333333333333333"

  static const int kMaxCharsEcmaScriptShortest = 25;

  enum Flags {

    NO_FLAGS = 0,

    EMIT_POSITIVE_EXPONENT_SIGN = 1,

    EMIT_TRAILING_DECIMAL_POINT = 2,

    EMIT_TRAILING_ZERO_AFTER_POINT = 4,

    UNIQUE_ZERO = 8,

    NO_TRAILING_ZERO = 16,

    EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL = 32,

    EMIT_TRAILING_ZERO_AFTER_POINT_IN_EXPONENTIAL = 64

  };

  // Flags should be a bit-or combination of the possible Flags-enum.

  //  - NO_FLAGS: no special flags.

  //  - EMIT_POSITIVE_EXPONENT_SIGN: when the number is converted into exponent

  //    form, emits a '+' for positive exponents. Example: 1.2e+2.

  //  - EMIT_TRAILING_DECIMAL_POINT: when the input number is an integer and is

  //    converted into decimal format then a trailing decimal point is appended.

  //    Example: 2345.0 is converted to "2345.".

  //  - EMIT_TRAILING_ZERO_AFTER_POINT: in addition to a trailing decimal point

  //    emits a trailing '0'-character. This flag requires the

  //    EMIT_TRAILING_DECIMAL_POINT flag.

  //    Example: 2345.0 is converted to "2345.0".

  //  - UNIQUE_ZERO: "-0.0" is converted to "0.0".

  //  - NO_TRAILING_ZERO: Trailing zeros are removed from the fractional portion

  //    of the result in precision mode. Matches printf's %g.

  //    When EMIT_TRAILING_ZERO_AFTER_POINT is also given, one trailing zero is

  //    preserved.

  //  - EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL: when the input number has

  //    exactly one significant digit and is converted into exponent form then a

  //    trailing decimal point is appended to the significand in shortest mode

  //    or in precision mode with one requested digit.

  //  - EMIT_TRAILING_ZERO_AFTER_POINT_IN_EXPONENTIAL: in addition to a trailing

  //    decimal point emits a trailing '0'-character. This flag requires the

  //    EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL flag.

  //

  // Infinity symbol and nan_symbol provide the string representation for these

  // special values. If the string is NULL and the special value is encountered

  // then the conversion functions return false.

  //

  // The exponent_character is used in exponential representations. It is

  // usually 'e' or 'E'.

  //

  // When converting to the shortest representation the converter will

  // represent input numbers in decimal format if they are in the interval

  // [10^decimal_in_shortest_low; 10^decimal_in_shortest_high[

  //    (lower boundary included, greater boundary excluded).

  // Example: with decimal_in_shortest_low = -6 and

  //               decimal_in_shortest_high = 21:

  //   ToShortest(0.000001)  -> "0.000001"

  //   ToShortest(0.0000001) -> "1e-7"

  //   ToShortest(111111111111111111111.0)  -> "111111111111111110000"

  //   ToShortest(100000000000000000000.0)  -> "100000000000000000000"

  //   ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"

  //

  // When converting to precision mode the converter may add

  // max_leading_padding_zeroes before returning the number in exponential

  // format.

  // Example with max_leading_padding_zeroes_in_precision_mode = 6.

  //   ToPrecision(0.0000012345, 2) -> "0.0000012"

  //   ToPrecision(0.00000012345, 2) -> "1.2e-7"

  // Similarly the converter may add up to

  // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid

  // returning an exponential representation. A zero added by the

  // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.

  // Examples for max_trailing_padding_zeroes_in_precision_mode = 1:

  //   ToPrecision(230.0, 2) -> "230"

  //   ToPrecision(230.0, 2) -> "230."  with EMIT_TRAILING_DECIMAL_POINT.

  //   ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.

  //

  // When converting numbers with exactly one significant digit to exponent

  // form in shortest mode or in precision mode with one requested digit, the

  // EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT flags have

  // no effect. Use the EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL flag to

  // append a decimal point in this case and the

  // EMIT_TRAILING_ZERO_AFTER_POINT_IN_EXPONENTIAL flag to also append a

  // '0'-character in this case.

  // Example with decimal_in_shortest_low = 0:

  //   ToShortest(0.0009) -> "9e-4"

  //     with EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL deactivated.

  //   ToShortest(0.0009) -> "9.e-4"

  //     with EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL activated.

  //   ToShortest(0.0009) -> "9.0e-4"

  //     with EMIT_TRAILING_DECIMAL_POINT_IN_EXPONENTIAL activated and

  //     EMIT_TRAILING_ZERO_AFTER_POINT_IN_EXPONENTIAL activated.

  //

  // The min_exponent_width is used for exponential representations.

  // The converter adds leading '0's to the exponent until the exponent

  // is at least min_exponent_width digits long.

  // The min_exponent_width is clamped to 5.

  // As such, the exponent may never have more than 5 digits in total.

  DoubleToStringConverter(int flags,

                          const char* infinity_symbol,

                          const char* nan_symbol,

                          char exponent_character,

                          int decimal_in_shortest_low,

                          int decimal_in_shortest_high,

                          int max_leading_padding_zeroes_in_precision_mode,

                          int max_trailing_padding_zeroes_in_precision_mode,

                          int min_exponent_width = 0)

      : flags_(flags),

        infinity_symbol_(infinity_symbol),

        nan_symbol_(nan_symbol),

        exponent_character_(exponent_character),

        decimal_in_shortest_low_(decimal_in_shortest_low),

        decimal_in_shortest_high_(decimal_in_shortest_high),

        max_leading_padding_zeroes_in_precision_mode_(

            max_leading_padding_zeroes_in_precision_mode),

        max_trailing_padding_zeroes_in_precision_mode_(

            max_trailing_padding_zeroes_in_precision_mode),

        min_exponent_width_(min_exponent_width) {

    // When 'trailing zero after the point' is set, then 'trailing point'

    // must be set too.

    DOUBLE_CONVERSION_ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) ||

        !((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0));

  }

  // Returns a converter following the EcmaScript specification.

  //

  // Flags: UNIQUE_ZERO and EMIT_POSITIVE_EXPONENT_SIGN.

  // Special values: "Infinity" and "NaN".

  // Lower case 'e' for exponential values.

  // decimal_in_shortest_low: -6

  // decimal_in_shortest_high: 21

  // max_leading_padding_zeroes_in_precision_mode: 6

  // max_trailing_padding_zeroes_in_precision_mode: 0

  static const DoubleToStringConverter& EcmaScriptConverter();

  // Computes the shortest string of digits that correctly represent the input

  // number. Depending on decimal_in_shortest_low and decimal_in_shortest_high

  // (see constructor) it then either returns a decimal representation, or an

  // exponential representation.

  // Example with decimal_in_shortest_low = -6,

  //              decimal_in_shortest_high = 21,

  //              EMIT_POSITIVE_EXPONENT_SIGN activated, and

  //              EMIT_TRAILING_DECIMAL_POINT deactivated:

  //   ToShortest(0.000001)  -> "0.000001"

  //   ToShortest(0.0000001) -> "1e-7"

  //   ToShortest(111111111111111111111.0)  -> "111111111111111110000"

  //   ToShortest(100000000000000000000.0)  -> "100000000000000000000"

  //   ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"

  //

  // Note: the conversion may round the output if the returned string

  // is accurate enough to uniquely identify the input-number.

  // For example the most precise representation of the double 9e59 equals

  // "899999999999999918767229449717619953810131273674690656206848", but

  // the converter will return the shorter (but still correct) "9e59".

  //

  // Returns true if the conversion succeeds. The conversion always succeeds

  // except when the input value is special and no infinity_symbol or

  // nan_symbol has been given to the constructor.

  //

  // The length of the longest result is the maximum of the length of the

  // following string representations (each with possible examples):

  // - NaN and negative infinity: "NaN", "-Infinity", "-inf".

  // - -10^(decimal_in_shortest_high - 1):

  //      "-100000000000000000000", "-1000000000000000.0"

  // - the longest string in range [0; -10^decimal_in_shortest_low]. Generally,

  //   this string is 3 + kBase10MaximalLength - decimal_in_shortest_low.

  //   (Sign, '0', decimal point, padding zeroes for decimal_in_shortest_low,

  //   and the significant digits).

  //      "-0.0000033333333333333333", "-0.0012345678901234567"

  // - the longest exponential representation. (A negative number with

  //   kBase10MaximalLength significant digits).

  //      "-1.7976931348623157e+308", "-1.7976931348623157E308"

  // In addition, the buffer must be able to hold the trailing '\0' character.

  bool ToShortest(double value, StringBuilder* result_builder) const {

    return ToShortestIeeeNumber(value, result_builder, SHORTEST);

  }

  // Same as ToShortest, but for single-precision floats.

  bool ToShortestSingle(float value, StringBuilder* result_builder) const {

    return ToShortestIeeeNumber(value, result_builder, SHORTEST_SINGLE);

  }

  // Computes a decimal representation with a fixed number of digits after the

  // decimal point. The last emitted digit is rounded.

  //

  // Examples:

  //   ToFixed(3.12, 1) -> "3.1"

  //   ToFixed(3.1415, 3) -> "3.142"

  //   ToFixed(1234.56789, 4) -> "1234.5679"

  //   ToFixed(1.23, 5) -> "1.23000"

  //   ToFixed(0.1, 4) -> "0.1000"

  //   ToFixed(1e30, 2) -> "1000000000000000019884624838656.00"

  //   ToFixed(0.1, 30) -> "0.100000000000000005551115123126"

  //   ToFixed(0.1, 17) -> "0.10000000000000001"

  //

  // If requested_digits equals 0, then the tail of the result depends on

  // the EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT.

  // Examples, for requested_digits == 0,

  //   let EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT be

  //    - false and false: then 123.45 -> 123

  //                             0.678 -> 1

  //    - true and false: then 123.45 -> 123.

  //                            0.678 -> 1.

  //    - true and true: then 123.45 -> 123.0

  //                           0.678 -> 1.0

  //

  // Returns true if the conversion succeeds. The conversion always succeeds

  // except for the following cases:

  //   - the input value is special and no infinity_symbol or nan_symbol has

  //     been provided to the constructor,

  //   - 'value' > 10^kMaxFixedDigitsBeforePoint, or

  //   - 'requested_digits' > kMaxFixedDigitsAfterPoint.

  // The last two conditions imply that the result for non-special values never

  // contains more than

  //  1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters

  // (one additional character for the sign, and one for the decimal point).

  // In addition, the buffer must be able to hold the trailing '\0' character.

  bool ToFixed(double value,

               int requested_digits,

               StringBuilder* result_builder) const;

  // Computes a representation in exponential format with requested_digits

  // after the decimal point. The last emitted digit is rounded.

  // If requested_digits equals -1, then the shortest exponential representation

  // is computed.

  //

  // Examples with EMIT_POSITIVE_EXPONENT_SIGN deactivated, and

  //               exponent_character set to 'e'.

  //   ToExponential(3.12, 1) -> "3.1e0"

  //   ToExponential(5.0, 3) -> "5.000e0"

  //   ToExponential(0.001, 2) -> "1.00e-3"

  //   ToExponential(3.1415, -1) -> "3.1415e0"

  //   ToExponential(3.1415, 4) -> "3.1415e0"

  //   ToExponential(3.1415, 3) -> "3.142e0"

  //   ToExponential(123456789000000, 3) -> "1.235e14"

  //   ToExponential(1000000000000000019884624838656.0, -1) -> "1e30"

  //   ToExponential(1000000000000000019884624838656.0, 32) ->

  //                     "1.00000000000000001988462483865600e30"

  //   ToExponential(1234, 0) -> "1e3"

  //

  // Returns true if the conversion succeeds. The conversion always succeeds

  // except for the following cases:

  //   - the input value is special and no infinity_symbol or nan_symbol has

  //     been provided to the constructor,

  //   - 'requested_digits' > kMaxExponentialDigits.

  //

  // The last condition implies that the result never contains more than

  // kMaxExponentialDigits + 8 characters (the sign, the digit before the

  // decimal point, the decimal point, the exponent character, the

  // exponent's sign, and at most 3 exponent digits).

  // In addition, the buffer must be able to hold the trailing '\0' character.

  bool ToExponential(double value,

                     int requested_digits,

                     StringBuilder* result_builder) const;

  // Computes 'precision' leading digits of the given 'value' and returns them

  // either in exponential or decimal format, depending on

  // max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the

  // constructor).

  // The last computed digit is rounded.

  //

  // Example with max_leading_padding_zeroes_in_precision_mode = 6.

  //   ToPrecision(0.0000012345, 2) -> "0.0000012"

  //   ToPrecision(0.00000012345, 2) -> "1.2e-7"

  // Similarly the converter may add up to

  // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid

  // returning an exponential representation. A zero added by the

  // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.

  // Examples for max_trailing_padding_zeroes_in_precision_mode = 1:

  //   ToPrecision(230.0, 2) -> "230"

  //   ToPrecision(230.0, 2) -> "230."  with EMIT_TRAILING_DECIMAL_POINT.

  //   ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.

  // Examples for max_trailing_padding_zeroes_in_precision_mode = 3, and no

  //    EMIT_TRAILING_ZERO_AFTER_POINT:

  //   ToPrecision(123450.0, 6) -> "123450"

  //   ToPrecision(123450.0, 5) -> "123450"

  //   ToPrecision(123450.0, 4) -> "123500"

  //   ToPrecision(123450.0, 3) -> "123000"

  //   ToPrecision(123450.0, 2) -> "1.2e5"

  //

  // Returns true if the conversion succeeds. The conversion always succeeds

  // except for the following cases:

  //   - the input value is special and no infinity_symbol or nan_symbol has

  //     been provided to the constructor,

  //   - precision < kMinPericisionDigits

  //   - precision > kMaxPrecisionDigits

  //

  // The last condition implies that the result never contains more than

  // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the

  // exponent character, the exponent's sign, and at most 3 exponent digits).

  // In addition, the buffer must be able to hold the trailing '\0' character.

  bool ToPrecision(double value,

                   int precision,

                   StringBuilder* result_builder) const;

  enum DtoaMode {

    // Produce the shortest correct representation.

    // For example the output of 0.299999999999999988897 is (the less accurate

    // but correct) 0.3.

    SHORTEST,

    // Same as SHORTEST, but for single-precision floats.

    SHORTEST_SINGLE,

    // Produce a fixed number of digits after the decimal point.

    // For instance fixed(0.1, 4) becomes 0.1000

    // If the input number is big, the output will be big.

    FIXED,

    // Fixed number of digits (independent of the decimal point).

    PRECISION

  };

  // Converts the given double 'v' to digit characters. 'v' must not be NaN,

  // +Infinity, or -Infinity. In SHORTEST_SINGLE-mode this restriction also

  // applies to 'v' after it has been casted to a single-precision float. That

  // is, in this mode static_cast<float>(v) must not be NaN, +Infinity or

  // -Infinity.

  //

  // The result should be interpreted as buffer * 10^(point-length).

  //

  // The digits are written to the buffer in the platform's charset, which is

  // often UTF-8 (with ASCII-range digits) but may be another charset, such

  // as EBCDIC.

  //

  // The output depends on the given mode:

  //  - SHORTEST: produce the least amount of digits for which the internal

  //   identity requirement is still satisfied. If the digits are printed

  //   (together with the correct exponent) then reading this number will give

  //   'v' again. The buffer will choose the representation that is closest to

  //   'v'. If there are two at the same distance, than the one farther away

  //   from 0 is chosen (halfway cases - ending with 5 - are rounded up).

  //   In this mode the 'requested_digits' parameter is ignored.

  //  - SHORTEST_SINGLE: same as SHORTEST but with single-precision.

  //  - FIXED: produces digits necessary to print a given number with

  //   'requested_digits' digits after the decimal point. The produced digits

  //   might be too short in which case the caller has to fill the remainder

  //   with '0's.

  //   Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.

  //   Halfway cases are rounded towards +/-Infinity (away from 0). The call

  //   toFixed(0.15, 2) thus returns buffer="2", point=0.

  //   The returned buffer may contain digits that would be truncated from the

  //   shortest representation of the input.

  //  - PRECISION: produces 'requested_digits' where the first digit is not '0'.

  //   Even though the length of produced digits usually equals

  //   'requested_digits', the function is allowed to return fewer digits, in

  //   which case the caller has to fill the missing digits with '0's.

  //   Halfway cases are again rounded away from 0.

  // DoubleToAscii expects the given buffer to be big enough to hold all

  // digits and a terminating null-character. In SHORTEST-mode it expects a

  // buffer of at least kBase10MaximalLength + 1. In all other modes the

  // requested_digits parameter and the padding-zeroes limit the size of the

  // output. Don't forget the decimal point, the exponent character and the

  // terminating null-character when computing the maximal output size.

  // The given length is only used in debug mode to ensure the buffer is big

  // enough.

  static void DoubleToAscii(double v,

                            DtoaMode mode,

                            int requested_digits,

                            char* buffer,

                            int buffer_length,

                            bool* sign,

                            int* length,

                            int* point);

 private:

  // Implementation for ToShortest and ToShortestSingle.

  bool ToShortestIeeeNumber(double value,

                            StringBuilder* result_builder,

                            DtoaMode mode) const;

  // If the value is a special value (NaN or Infinity) constructs the

  // corresponding string using the configured infinity/nan-symbol.

  // If either of them is NULL or the value is not special then the

  // function returns false.

  bool HandleSpecialValues(double value, StringBuilder* result_builder) const;

  // Constructs an exponential representation (i.e. 1.234e56).

  // The given exponent assumes a decimal point after the first decimal digit.

  void CreateExponentialRepresentation(const char* decimal_digits,

                                       int length,

                                       int exponent,

                                       StringBuilder* result_builder) const;

  // Creates a decimal representation (i.e 1234.5678).

  void CreateDecimalRepresentation(const char* decimal_digits,

                                   int length,

                                   int decimal_point,

                                   int digits_after_point,

                                   StringBuilder* result_builder) const;

  const int flags_;

  const char* const infinity_symbol_;

  const char* const nan_symbol_;

  const char exponent_character_;

  const int decimal_in_shortest_low_;

  const int decimal_in_shortest_high_;

  const int max_leading_padding_zeroes_in_precision_mode_;

  const int max_trailing_padding_zeroes_in_precision_mode_;

  const int min_exponent_width_;

  DOUBLE_CONVERSION_DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter);

};

}  // namespace double_conversion

#endif  // DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_