The Tor Browser: mfbt/double-conversion/double-conversion.h@97036ab72558 (annotated)

mfbt/double-conversion/double-conversion.h@97036ab72558 (annotated)

mfbt/double-conversion/double-conversion.h

Tue, 06 Jan 2015 21:39:09 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Tue, 06 Jan 2015 21:39:09 +0100
branch: TOR_BUG_9701
changeset 8: 97036ab72558
permissions: -rw-r--r--

Conditionally force memory storage according to privacy.thirdparty.isolate;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.

 // Copyright 2012 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
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #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_

The Tor Browser / annotate

mfbt/double-conversion/double-conversion.h@97036ab72558 (annotated)

mfbt/double-conversion/double-conversion.h