// Copyright 2010 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 "wtf/dtoa/utils.h"
namespace WTF {
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;
// 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,
// 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.
// 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.
// - 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 (+ 1 for the null-character) limits the size of
// the output. 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:
// 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:
// Performs the conversion.
// The output parameter 'processed_characters_count' is set to the number
// of characters that have been processed to read the number.
static double StringToDouble(const char* buffer, size_t length, size_t* processed_characters_count);
private:
DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter);
};
} // namespace double_conversion
} // namespace WTF
#endif // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_