420 lines
20 KiB
C++
420 lines
20 KiB
C++
// © 2018 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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//
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// From the double-conversion library. Original license:
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//
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// Copyright 2012 the V8 project authors. All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following
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// disclaimer in the documentation and/or other materials provided
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// with the distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
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#include "unicode/utypes.h"
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#if !UCONFIG_NO_FORMATTING
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#ifndef DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_
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#define DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_
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// ICU PATCH: Customize header file paths for ICU.
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#include "double-conversion-utils.h"
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// ICU PATCH: Wrap in ICU namespace
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U_NAMESPACE_BEGIN
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namespace double_conversion {
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class DoubleToStringConverter {
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public:
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#if 0 // not needed for ICU
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// When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint
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// or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the
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// function returns false.
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static const int kMaxFixedDigitsBeforePoint = 60;
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static const int kMaxFixedDigitsAfterPoint = 60;
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// When calling ToExponential with a requested_digits
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// parameter > kMaxExponentialDigits then the function returns false.
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static const int kMaxExponentialDigits = 120;
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// When calling ToPrecision with a requested_digits
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// parameter < kMinPrecisionDigits or requested_digits > kMaxPrecisionDigits
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// then the function returns false.
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static const int kMinPrecisionDigits = 1;
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static const int kMaxPrecisionDigits = 120;
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enum Flags {
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NO_FLAGS = 0,
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EMIT_POSITIVE_EXPONENT_SIGN = 1,
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EMIT_TRAILING_DECIMAL_POINT = 2,
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EMIT_TRAILING_ZERO_AFTER_POINT = 4,
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UNIQUE_ZERO = 8
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};
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// Flags should be a bit-or combination of the possible Flags-enum.
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// - NO_FLAGS: no special flags.
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// - EMIT_POSITIVE_EXPONENT_SIGN: when the number is converted into exponent
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// form, emits a '+' for positive exponents. Example: 1.2e+2.
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// - EMIT_TRAILING_DECIMAL_POINT: when the input number is an integer and is
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// converted into decimal format then a trailing decimal point is appended.
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// Example: 2345.0 is converted to "2345.".
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// - EMIT_TRAILING_ZERO_AFTER_POINT: in addition to a trailing decimal point
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// emits a trailing '0'-character. This flag requires the
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// EXMIT_TRAILING_DECIMAL_POINT flag.
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// Example: 2345.0 is converted to "2345.0".
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// - UNIQUE_ZERO: "-0.0" is converted to "0.0".
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//
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// Infinity symbol and nan_symbol provide the string representation for these
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// special values. If the string is NULL and the special value is encountered
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// then the conversion functions return false.
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//
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// The exponent_character is used in exponential representations. It is
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// usually 'e' or 'E'.
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//
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// When converting to the shortest representation the converter will
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// represent input numbers in decimal format if they are in the interval
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// [10^decimal_in_shortest_low; 10^decimal_in_shortest_high[
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// (lower boundary included, greater boundary excluded).
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// Example: with decimal_in_shortest_low = -6 and
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// decimal_in_shortest_high = 21:
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// ToShortest(0.000001) -> "0.000001"
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// ToShortest(0.0000001) -> "1e-7"
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// ToShortest(111111111111111111111.0) -> "111111111111111110000"
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// ToShortest(100000000000000000000.0) -> "100000000000000000000"
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// ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"
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//
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// When converting to precision mode the converter may add
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// max_leading_padding_zeroes before returning the number in exponential
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// format.
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// Example with max_leading_padding_zeroes_in_precision_mode = 6.
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// ToPrecision(0.0000012345, 2) -> "0.0000012"
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// ToPrecision(0.00000012345, 2) -> "1.2e-7"
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// Similarily the converter may add up to
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// max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid
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// returning an exponential representation. A zero added by the
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// EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.
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// Examples for max_trailing_padding_zeroes_in_precision_mode = 1:
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// ToPrecision(230.0, 2) -> "230"
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// ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT.
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// ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.
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//
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// The min_exponent_width is used for exponential representations.
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// The converter adds leading '0's to the exponent until the exponent
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// is at least min_exponent_width digits long.
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// The min_exponent_width is clamped to 5.
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// As such, the exponent may never have more than 5 digits in total.
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DoubleToStringConverter(int flags,
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const char* infinity_symbol,
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const char* nan_symbol,
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char exponent_character,
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int decimal_in_shortest_low,
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int decimal_in_shortest_high,
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int max_leading_padding_zeroes_in_precision_mode,
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int max_trailing_padding_zeroes_in_precision_mode,
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int min_exponent_width = 0)
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: flags_(flags),
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infinity_symbol_(infinity_symbol),
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nan_symbol_(nan_symbol),
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exponent_character_(exponent_character),
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decimal_in_shortest_low_(decimal_in_shortest_low),
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decimal_in_shortest_high_(decimal_in_shortest_high),
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max_leading_padding_zeroes_in_precision_mode_(
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max_leading_padding_zeroes_in_precision_mode),
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max_trailing_padding_zeroes_in_precision_mode_(
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max_trailing_padding_zeroes_in_precision_mode),
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min_exponent_width_(min_exponent_width) {
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// When 'trailing zero after the point' is set, then 'trailing point'
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// must be set too.
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DOUBLE_CONVERSION_ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) ||
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!((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0));
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}
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// Returns a converter following the EcmaScript specification.
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static const DoubleToStringConverter& EcmaScriptConverter();
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// Computes the shortest string of digits that correctly represent the input
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// number. Depending on decimal_in_shortest_low and decimal_in_shortest_high
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// (see constructor) it then either returns a decimal representation, or an
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// exponential representation.
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// Example with decimal_in_shortest_low = -6,
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// decimal_in_shortest_high = 21,
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// EMIT_POSITIVE_EXPONENT_SIGN activated, and
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// EMIT_TRAILING_DECIMAL_POINT deactived:
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// ToShortest(0.000001) -> "0.000001"
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// ToShortest(0.0000001) -> "1e-7"
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// ToShortest(111111111111111111111.0) -> "111111111111111110000"
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// ToShortest(100000000000000000000.0) -> "100000000000000000000"
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// ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"
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//
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// Note: the conversion may round the output if the returned string
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// is accurate enough to uniquely identify the input-number.
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// For example the most precise representation of the double 9e59 equals
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// "899999999999999918767229449717619953810131273674690656206848", but
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// the converter will return the shorter (but still correct) "9e59".
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//
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// Returns true if the conversion succeeds. The conversion always succeeds
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// except when the input value is special and no infinity_symbol or
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// nan_symbol has been given to the constructor.
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bool ToShortest(double value, StringBuilder* result_builder) const {
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return ToShortestIeeeNumber(value, result_builder, SHORTEST);
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}
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// Same as ToShortest, but for single-precision floats.
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bool ToShortestSingle(float value, StringBuilder* result_builder) const {
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return ToShortestIeeeNumber(value, result_builder, SHORTEST_SINGLE);
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}
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// Computes a decimal representation with a fixed number of digits after the
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// decimal point. The last emitted digit is rounded.
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//
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// Examples:
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// ToFixed(3.12, 1) -> "3.1"
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// ToFixed(3.1415, 3) -> "3.142"
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// ToFixed(1234.56789, 4) -> "1234.5679"
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// ToFixed(1.23, 5) -> "1.23000"
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// ToFixed(0.1, 4) -> "0.1000"
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// ToFixed(1e30, 2) -> "1000000000000000019884624838656.00"
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// ToFixed(0.1, 30) -> "0.100000000000000005551115123126"
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// ToFixed(0.1, 17) -> "0.10000000000000001"
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//
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// If requested_digits equals 0, then the tail of the result depends on
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// the EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT.
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// Examples, for requested_digits == 0,
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// let EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT be
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// - false and false: then 123.45 -> 123
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// 0.678 -> 1
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// - true and false: then 123.45 -> 123.
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// 0.678 -> 1.
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// - true and true: then 123.45 -> 123.0
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// 0.678 -> 1.0
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//
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// Returns true if the conversion succeeds. The conversion always succeeds
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// except for the following cases:
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// - the input value is special and no infinity_symbol or nan_symbol has
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// been provided to the constructor,
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// - 'value' > 10^kMaxFixedDigitsBeforePoint, or
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// - 'requested_digits' > kMaxFixedDigitsAfterPoint.
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// The last two conditions imply that the result will never contain more than
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// 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters
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// (one additional character for the sign, and one for the decimal point).
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bool ToFixed(double value,
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int requested_digits,
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StringBuilder* result_builder) const;
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// Computes a representation in exponential format with requested_digits
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// after the decimal point. The last emitted digit is rounded.
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// If requested_digits equals -1, then the shortest exponential representation
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// is computed.
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//
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// Examples with EMIT_POSITIVE_EXPONENT_SIGN deactivated, and
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// exponent_character set to 'e'.
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// ToExponential(3.12, 1) -> "3.1e0"
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// ToExponential(5.0, 3) -> "5.000e0"
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// ToExponential(0.001, 2) -> "1.00e-3"
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// ToExponential(3.1415, -1) -> "3.1415e0"
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// ToExponential(3.1415, 4) -> "3.1415e0"
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// ToExponential(3.1415, 3) -> "3.142e0"
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// ToExponential(123456789000000, 3) -> "1.235e14"
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// ToExponential(1000000000000000019884624838656.0, -1) -> "1e30"
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// ToExponential(1000000000000000019884624838656.0, 32) ->
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// "1.00000000000000001988462483865600e30"
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// ToExponential(1234, 0) -> "1e3"
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//
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// Returns true if the conversion succeeds. The conversion always succeeds
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// except for the following cases:
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// - the input value is special and no infinity_symbol or nan_symbol has
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// been provided to the constructor,
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// - 'requested_digits' > kMaxExponentialDigits.
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// The last condition implies that the result will never contain more than
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// kMaxExponentialDigits + 8 characters (the sign, the digit before the
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// decimal point, the decimal point, the exponent character, the
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// exponent's sign, and at most 3 exponent digits).
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bool ToExponential(double value,
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int requested_digits,
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StringBuilder* result_builder) const;
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// Computes 'precision' leading digits of the given 'value' and returns them
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// either in exponential or decimal format, depending on
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// max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the
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// constructor).
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// The last computed digit is rounded.
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//
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// Example with max_leading_padding_zeroes_in_precision_mode = 6.
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// ToPrecision(0.0000012345, 2) -> "0.0000012"
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// ToPrecision(0.00000012345, 2) -> "1.2e-7"
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// Similarily the converter may add up to
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// max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid
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// returning an exponential representation. A zero added by the
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// EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.
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// Examples for max_trailing_padding_zeroes_in_precision_mode = 1:
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// ToPrecision(230.0, 2) -> "230"
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// ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT.
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// ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.
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// Examples for max_trailing_padding_zeroes_in_precision_mode = 3, and no
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// EMIT_TRAILING_ZERO_AFTER_POINT:
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// ToPrecision(123450.0, 6) -> "123450"
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// ToPrecision(123450.0, 5) -> "123450"
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// ToPrecision(123450.0, 4) -> "123500"
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// ToPrecision(123450.0, 3) -> "123000"
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// ToPrecision(123450.0, 2) -> "1.2e5"
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//
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// Returns true if the conversion succeeds. The conversion always succeeds
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// except for the following cases:
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// - the input value is special and no infinity_symbol or nan_symbol has
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// been provided to the constructor,
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// - precision < kMinPericisionDigits
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// - precision > kMaxPrecisionDigits
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// The last condition implies that the result will never contain more than
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// kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the
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// exponent character, the exponent's sign, and at most 3 exponent digits).
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bool ToPrecision(double value,
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int precision,
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StringBuilder* result_builder) const;
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#endif // not needed for ICU
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enum DtoaMode {
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// Produce the shortest correct representation.
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// For example the output of 0.299999999999999988897 is (the less accurate
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// but correct) 0.3.
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SHORTEST,
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// Same as SHORTEST, but for single-precision floats.
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SHORTEST_SINGLE,
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// Produce a fixed number of digits after the decimal point.
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// For instance fixed(0.1, 4) becomes 0.1000
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// If the input number is big, the output will be big.
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FIXED,
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// Fixed number of digits (independent of the decimal point).
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PRECISION
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};
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// The maximal number of digits that are needed to emit a double in base 10.
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// A higher precision can be achieved by using more digits, but the shortest
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// accurate representation of any double will never use more digits than
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// kBase10MaximalLength.
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// Note that DoubleToAscii null-terminates its input. So the given buffer
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// should be at least kBase10MaximalLength + 1 characters long.
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static const int kBase10MaximalLength = 17;
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// Converts the given double 'v' to digit characters. 'v' must not be NaN,
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// +Infinity, or -Infinity. In SHORTEST_SINGLE-mode this restriction also
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// applies to 'v' after it has been casted to a single-precision float. That
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// is, in this mode static_cast<float>(v) must not be NaN, +Infinity or
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// -Infinity.
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//
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// The result should be interpreted as buffer * 10^(point-length).
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//
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// The digits are written to the buffer in the platform's charset, which is
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// often UTF-8 (with ASCII-range digits) but may be another charset, such
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// as EBCDIC.
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//
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// The output depends on the given mode:
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// - SHORTEST: produce the least amount of digits for which the internal
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// identity requirement is still satisfied. If the digits are printed
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// (together with the correct exponent) then reading this number will give
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// 'v' again. The buffer will choose the representation that is closest to
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// 'v'. If there are two at the same distance, than the one farther away
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// from 0 is chosen (halfway cases - ending with 5 - are rounded up).
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// In this mode the 'requested_digits' parameter is ignored.
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// - SHORTEST_SINGLE: same as SHORTEST but with single-precision.
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// - FIXED: produces digits necessary to print a given number with
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// 'requested_digits' digits after the decimal point. The produced digits
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// might be too short in which case the caller has to fill the remainder
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// with '0's.
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// Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.
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// Halfway cases are rounded towards +/-Infinity (away from 0). The call
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// toFixed(0.15, 2) thus returns buffer="2", point=0.
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// The returned buffer may contain digits that would be truncated from the
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// shortest representation of the input.
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// - PRECISION: produces 'requested_digits' where the first digit is not '0'.
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// Even though the length of produced digits usually equals
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// 'requested_digits', the function is allowed to return fewer digits, in
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// which case the caller has to fill the missing digits with '0's.
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// Halfway cases are again rounded away from 0.
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// DoubleToAscii expects the given buffer to be big enough to hold all
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// digits and a terminating null-character. In SHORTEST-mode it expects a
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// buffer of at least kBase10MaximalLength + 1. In all other modes the
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// requested_digits parameter and the padding-zeroes limit the size of the
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// output. Don't forget the decimal point, the exponent character and the
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// terminating null-character when computing the maximal output size.
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// The given length is only used in debug mode to ensure the buffer is big
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// enough.
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// ICU PATCH: Export this as U_I18N_API for unit tests.
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static void U_I18N_API DoubleToAscii(double v,
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DtoaMode mode,
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int requested_digits,
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char* buffer,
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int buffer_length,
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bool* sign,
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int* length,
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int* point);
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#if 0 // not needed for ICU
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private:
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// Implementation for ToShortest and ToShortestSingle.
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bool ToShortestIeeeNumber(double value,
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StringBuilder* result_builder,
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DtoaMode mode) const;
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// If the value is a special value (NaN or Infinity) constructs the
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// corresponding string using the configured infinity/nan-symbol.
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// If either of them is NULL or the value is not special then the
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// function returns false.
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bool HandleSpecialValues(double value, StringBuilder* result_builder) const;
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// Constructs an exponential representation (i.e. 1.234e56).
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// The given exponent assumes a decimal point after the first decimal digit.
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void CreateExponentialRepresentation(const char* decimal_digits,
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int length,
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int exponent,
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StringBuilder* result_builder) const;
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// Creates a decimal representation (i.e 1234.5678).
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void CreateDecimalRepresentation(const char* decimal_digits,
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int length,
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int decimal_point,
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int digits_after_point,
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StringBuilder* result_builder) const;
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const int flags_;
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const char* const infinity_symbol_;
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const char* const nan_symbol_;
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const char exponent_character_;
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const int decimal_in_shortest_low_;
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const int decimal_in_shortest_high_;
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const int max_leading_padding_zeroes_in_precision_mode_;
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const int max_trailing_padding_zeroes_in_precision_mode_;
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const int min_exponent_width_;
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#endif // not needed for ICU
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DOUBLE_CONVERSION_DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter);
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};
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} // namespace double_conversion
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// ICU PATCH: Close ICU namespace
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U_NAMESPACE_END
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#endif // DOUBLE_CONVERSION_DOUBLE_TO_STRING_H_
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#endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING
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