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

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 #ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_

 #define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_

 #include "mozilla/Types.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 = 60;

   // 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;

   enum Flags {

     NO_FLAGS = 0,

     EMIT_POSITIVE_EXPONENT_SIGN = 1,

     EMIT_TRAILING_DECIMAL_POINT = 2,

     EMIT_TRAILING_ZERO_AFTER_POINT = 4,

     UNIQUE_ZERO = 8

   };

   // 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

   //    EXMIT_TRAILING_DECIMAL_POINT flag.

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

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

   //

   // 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"

   // Similarily 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.

   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)

       : 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) {

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

     // must be set too.

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

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

   }

   // Returns a converter following the EcmaScript specification.

   static MFBT_API 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 deactived:

   //   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.

   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 will never contain more than

   // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters

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

   MFBT_API 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 will never contain 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).

   MFBT_API 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"

   // Similarily 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 will never contain more than

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

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

   MFBT_API bool ToPrecision(double value,

                    int precision,

                    bool* used_exponential_notation,

                    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

   };

   // 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 MFBT_DATA int kBase10MaximalLength = 17;

   // Converts the given double 'v' to ascii. '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 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 MFBT_API 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.

   MFBT_API 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.

   MFBT_API 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.

   MFBT_API void CreateExponentialRepresentation(const char* decimal_digits,

                                        int length,

                                        int exponent,

                                        StringBuilder* result_builder) const;

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

   MFBT_API 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_;

   DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter);

 };

 class StringToDoubleConverter {

  public:

   // Enumeration for allowing octals and ignoring junk when converting

   // strings to numbers.

   enum Flags {

     NO_FLAGS = 0,

     ALLOW_HEX = 1,

     ALLOW_OCTALS = 2,

     ALLOW_TRAILING_JUNK = 4,

     ALLOW_LEADING_SPACES = 8,

     ALLOW_TRAILING_SPACES = 16,

     ALLOW_SPACES_AFTER_SIGN = 32

   };

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

   //  - NO_FLAGS: no special flags.

   //  - ALLOW_HEX: recognizes the prefix "0x". Hex numbers may only be integers.

   //      Ex: StringToDouble("0x1234") -> 4660.0

   //          In StringToDouble("0x1234.56") the characters ".56" are trailing

   //          junk. The result of the call is hence dependent on

   //          the ALLOW_TRAILING_JUNK flag and/or the junk value.

   //      With this flag "0x" is a junk-string. Even with ALLOW_TRAILING_JUNK,

   //      the string will not be parsed as "0" followed by junk.

   //

   //  - ALLOW_OCTALS: recognizes the prefix "0" for octals:

   //      If a sequence of octal digits starts with '0', then the number is

   //      read as octal integer. Octal numbers may only be integers.

   //      Ex: StringToDouble("01234") -> 668.0

   //          StringToDouble("012349") -> 12349.0  // Not a sequence of octal

   //                                               // digits.

   //          In StringToDouble("01234.56") the characters ".56" are trailing

   //          junk. The result of the call is hence dependent on

   //          the ALLOW_TRAILING_JUNK flag and/or the junk value.

   //          In StringToDouble("01234e56") the characters "e56" are trailing

   //          junk, too.

   //  - ALLOW_TRAILING_JUNK: ignore trailing characters that are not part of

   //      a double literal.

   //  - ALLOW_LEADING_SPACES: skip over leading spaces.

   //  - ALLOW_TRAILING_SPACES: ignore trailing spaces.

   //  - ALLOW_SPACES_AFTER_SIGN: ignore spaces after the sign.

   //       Ex: StringToDouble("-   123.2") -> -123.2.

   //           StringToDouble("+   123.2") -> 123.2

   //

   // empty_string_value is returned when an empty string is given as input.

   // If ALLOW_LEADING_SPACES or ALLOW_TRAILING_SPACES are set, then a string

   // containing only spaces is converted to the 'empty_string_value', too.

   //

   // junk_string_value is returned when

   //  a) ALLOW_TRAILING_JUNK is not set, and a junk character (a character not

   //     part of a double-literal) is found.

   //  b) ALLOW_TRAILING_JUNK is set, but the string does not start with a

   //     double literal.

   //

   // infinity_symbol and nan_symbol are strings that are used to detect

   // inputs that represent infinity and NaN. They can be null, in which case

   // they are ignored.

   // The conversion routine first reads any possible signs. Then it compares the

   // following character of the input-string with the first character of

   // the infinity, and nan-symbol. If either matches, the function assumes, that

   // a match has been found, and expects the following input characters to match

   // the remaining characters of the special-value symbol.

   // This means that the following restrictions apply to special-value symbols:

   //  - they must not start with signs ('+', or '-'),

   //  - they must not have the same first character.

   //  - they must not start with digits.

   //

   // Examples:

   //  flags = ALLOW_HEX | ALLOW_TRAILING_JUNK,

   //  empty_string_value = 0.0,

   //  junk_string_value = NaN,

   //  infinity_symbol = "infinity",

   //  nan_symbol = "nan":

   //    StringToDouble("0x1234") -> 4660.0.

   //    StringToDouble("0x1234K") -> 4660.0.

   //    StringToDouble("") -> 0.0  // empty_string_value.

   //    StringToDouble(" ") -> NaN  // junk_string_value.

   //    StringToDouble(" 1") -> NaN  // junk_string_value.

   //    StringToDouble("0x") -> NaN  // junk_string_value.

   //    StringToDouble("-123.45") -> -123.45.

   //    StringToDouble("--123.45") -> NaN  // junk_string_value.

   //    StringToDouble("123e45") -> 123e45.

   //    StringToDouble("123E45") -> 123e45.

   //    StringToDouble("123e+45") -> 123e45.

   //    StringToDouble("123E-45") -> 123e-45.

   //    StringToDouble("123e") -> 123.0  // trailing junk ignored.

   //    StringToDouble("123e-") -> 123.0  // trailing junk ignored.

   //    StringToDouble("+NaN") -> NaN  // NaN string literal.

   //    StringToDouble("-infinity") -> -inf.  // infinity literal.

   //    StringToDouble("Infinity") -> NaN  // junk_string_value.

   //

   //  flags = ALLOW_OCTAL | ALLOW_LEADING_SPACES,

   //  empty_string_value = 0.0,

   //  junk_string_value = NaN,

   //  infinity_symbol = NULL,

   //  nan_symbol = NULL:

   //    StringToDouble("0x1234") -> NaN  // junk_string_value.

   //    StringToDouble("01234") -> 668.0.

   //    StringToDouble("") -> 0.0  // empty_string_value.

   //    StringToDouble(" ") -> 0.0  // empty_string_value.

   //    StringToDouble(" 1") -> 1.0

   //    StringToDouble("0x") -> NaN  // junk_string_value.

   //    StringToDouble("0123e45") -> NaN  // junk_string_value.

   //    StringToDouble("01239E45") -> 1239e45.

   //    StringToDouble("-infinity") -> NaN  // junk_string_value.

   //    StringToDouble("NaN") -> NaN  // junk_string_value.

   StringToDoubleConverter(int flags,

                           double empty_string_value,

                           double junk_string_value,

                           const char* infinity_symbol,

                           const char* nan_symbol)

       : flags_(flags),

         empty_string_value_(empty_string_value),

         junk_string_value_(junk_string_value),

         infinity_symbol_(infinity_symbol),

         nan_symbol_(nan_symbol) {

   }

   // Performs the conversion.

   // The output parameter 'processed_characters_count' is set to the number

   // of characters that have been processed to read the number.

   // Spaces than are processed with ALLOW_{LEADING|TRAILING}_SPACES are included

   // in the 'processed_characters_count'. Trailing junk is never included.

   double StringToDouble(const char* buffer,

                         int length,

                         int* processed_characters_count) const {

     return StringToIeee(buffer, length, processed_characters_count, true);

   }

   // Same as StringToDouble but reads a float.

   // Note that this is not equivalent to static_cast<float>(StringToDouble(...))

   // due to potential double-rounding.

   float StringToFloat(const char* buffer,

                       int length,

                       int* processed_characters_count) const {

     return static_cast<float>(StringToIeee(buffer, length,

                                            processed_characters_count, false));

   }

  private:

   const int flags_;

   const double empty_string_value_;

   const double junk_string_value_;

   const char* const infinity_symbol_;

   const char* const nan_symbol_;

   double StringToIeee(const char* buffer,

                       int length,

                       int* processed_characters_count,

                       bool read_as_double) const;

   DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter);

 };

 }  // namespace double_conversion

 #endif  // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_