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 // Copyright 2012 the V8 project authors. All rights reserved.
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 //       from this software without specific prior written permission.
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 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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 #ifndef DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_
 #define DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_
 
 #include "utils.h"
 
 namespace arrow_vendored {
 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
 }  // namespace arrow_vendored
 
 #endif  // DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_

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