mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-22 12:51:42 +03:00
537 lines
26 KiB
C
537 lines
26 KiB
C
|
// 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 "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 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).
|
||
|
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).
|
||
|
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).
|
||
|
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
|
||
|
};
|
||
|
|
||
|
// 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;
|
||
|
|
||
|
// 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 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_;
|
||
|
|
||
|
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_
|