1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mfbt/double-conversion/double-conversion.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,538 @@
1.4 +// Copyright 2012 the V8 project authors. All rights reserved.
1.5 +// Redistribution and use in source and binary forms, with or without
1.6 +// modification, are permitted provided that the following conditions are
1.7 +// met:
1.8 +//
1.9 +// * Redistributions of source code must retain the above copyright
1.10 +// notice, this list of conditions and the following disclaimer.
1.11 +// * Redistributions in binary form must reproduce the above
1.12 +// copyright notice, this list of conditions and the following
1.13 +// disclaimer in the documentation and/or other materials provided
1.14 +// with the distribution.
1.15 +// * Neither the name of Google Inc. nor the names of its
1.16 +// contributors may be used to endorse or promote products derived
1.17 +// from this software without specific prior written permission.
1.18 +//
1.19 +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.20 +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.21 +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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1.23 +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
1.24 +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
1.25 +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
1.26 +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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1.30 +
1.31 +#ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
1.32 +#define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
1.33 +
1.34 +#include "mozilla/Types.h"
1.35 +#include "utils.h"
1.36 +
1.37 +namespace double_conversion {
1.38 +
1.39 +class DoubleToStringConverter {
1.40 + public:
1.41 + // When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint
1.42 + // or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the
1.43 + // function returns false.
1.44 + static const int kMaxFixedDigitsBeforePoint = 60;
1.45 + static const int kMaxFixedDigitsAfterPoint = 60;
1.46 +
1.47 + // When calling ToExponential with a requested_digits
1.48 + // parameter > kMaxExponentialDigits then the function returns false.
1.49 + static const int kMaxExponentialDigits = 120;
1.50 +
1.51 + // When calling ToPrecision with a requested_digits
1.52 + // parameter < kMinPrecisionDigits or requested_digits > kMaxPrecisionDigits
1.53 + // then the function returns false.
1.54 + static const int kMinPrecisionDigits = 1;
1.55 + static const int kMaxPrecisionDigits = 120;
1.56 +
1.57 + enum Flags {
1.58 + NO_FLAGS = 0,
1.59 + EMIT_POSITIVE_EXPONENT_SIGN = 1,
1.60 + EMIT_TRAILING_DECIMAL_POINT = 2,
1.61 + EMIT_TRAILING_ZERO_AFTER_POINT = 4,
1.62 + UNIQUE_ZERO = 8
1.63 + };
1.64 +
1.65 + // Flags should be a bit-or combination of the possible Flags-enum.
1.66 + // - NO_FLAGS: no special flags.
1.67 + // - EMIT_POSITIVE_EXPONENT_SIGN: when the number is converted into exponent
1.68 + // form, emits a '+' for positive exponents. Example: 1.2e+2.
1.69 + // - EMIT_TRAILING_DECIMAL_POINT: when the input number is an integer and is
1.70 + // converted into decimal format then a trailing decimal point is appended.
1.71 + // Example: 2345.0 is converted to "2345.".
1.72 + // - EMIT_TRAILING_ZERO_AFTER_POINT: in addition to a trailing decimal point
1.73 + // emits a trailing '0'-character. This flag requires the
1.74 + // EXMIT_TRAILING_DECIMAL_POINT flag.
1.75 + // Example: 2345.0 is converted to "2345.0".
1.76 + // - UNIQUE_ZERO: "-0.0" is converted to "0.0".
1.77 + //
1.78 + // Infinity symbol and nan_symbol provide the string representation for these
1.79 + // special values. If the string is NULL and the special value is encountered
1.80 + // then the conversion functions return false.
1.81 + //
1.82 + // The exponent_character is used in exponential representations. It is
1.83 + // usually 'e' or 'E'.
1.84 + //
1.85 + // When converting to the shortest representation the converter will
1.86 + // represent input numbers in decimal format if they are in the interval
1.87 + // [10^decimal_in_shortest_low; 10^decimal_in_shortest_high[
1.88 + // (lower boundary included, greater boundary excluded).
1.89 + // Example: with decimal_in_shortest_low = -6 and
1.90 + // decimal_in_shortest_high = 21:
1.91 + // ToShortest(0.000001) -> "0.000001"
1.92 + // ToShortest(0.0000001) -> "1e-7"
1.93 + // ToShortest(111111111111111111111.0) -> "111111111111111110000"
1.94 + // ToShortest(100000000000000000000.0) -> "100000000000000000000"
1.95 + // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"
1.96 + //
1.97 + // When converting to precision mode the converter may add
1.98 + // max_leading_padding_zeroes before returning the number in exponential
1.99 + // format.
1.100 + // Example with max_leading_padding_zeroes_in_precision_mode = 6.
1.101 + // ToPrecision(0.0000012345, 2) -> "0.0000012"
1.102 + // ToPrecision(0.00000012345, 2) -> "1.2e-7"
1.103 + // Similarily the converter may add up to
1.104 + // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid
1.105 + // returning an exponential representation. A zero added by the
1.106 + // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.
1.107 + // Examples for max_trailing_padding_zeroes_in_precision_mode = 1:
1.108 + // ToPrecision(230.0, 2) -> "230"
1.109 + // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT.
1.110 + // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.
1.111 + DoubleToStringConverter(int flags,
1.112 + const char* infinity_symbol,
1.113 + const char* nan_symbol,
1.114 + char exponent_character,
1.115 + int decimal_in_shortest_low,
1.116 + int decimal_in_shortest_high,
1.117 + int max_leading_padding_zeroes_in_precision_mode,
1.118 + int max_trailing_padding_zeroes_in_precision_mode)
1.119 + : flags_(flags),
1.120 + infinity_symbol_(infinity_symbol),
1.121 + nan_symbol_(nan_symbol),
1.122 + exponent_character_(exponent_character),
1.123 + decimal_in_shortest_low_(decimal_in_shortest_low),
1.124 + decimal_in_shortest_high_(decimal_in_shortest_high),
1.125 + max_leading_padding_zeroes_in_precision_mode_(
1.126 + max_leading_padding_zeroes_in_precision_mode),
1.127 + max_trailing_padding_zeroes_in_precision_mode_(
1.128 + max_trailing_padding_zeroes_in_precision_mode) {
1.129 + // When 'trailing zero after the point' is set, then 'trailing point'
1.130 + // must be set too.
1.131 + ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) ||
1.132 + !((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0));
1.133 + }
1.134 +
1.135 + // Returns a converter following the EcmaScript specification.
1.136 + static MFBT_API const DoubleToStringConverter& EcmaScriptConverter();
1.137 +
1.138 + // Computes the shortest string of digits that correctly represent the input
1.139 + // number. Depending on decimal_in_shortest_low and decimal_in_shortest_high
1.140 + // (see constructor) it then either returns a decimal representation, or an
1.141 + // exponential representation.
1.142 + // Example with decimal_in_shortest_low = -6,
1.143 + // decimal_in_shortest_high = 21,
1.144 + // EMIT_POSITIVE_EXPONENT_SIGN activated, and
1.145 + // EMIT_TRAILING_DECIMAL_POINT deactived:
1.146 + // ToShortest(0.000001) -> "0.000001"
1.147 + // ToShortest(0.0000001) -> "1e-7"
1.148 + // ToShortest(111111111111111111111.0) -> "111111111111111110000"
1.149 + // ToShortest(100000000000000000000.0) -> "100000000000000000000"
1.150 + // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21"
1.151 + //
1.152 + // Note: the conversion may round the output if the returned string
1.153 + // is accurate enough to uniquely identify the input-number.
1.154 + // For example the most precise representation of the double 9e59 equals
1.155 + // "899999999999999918767229449717619953810131273674690656206848", but
1.156 + // the converter will return the shorter (but still correct) "9e59".
1.157 + //
1.158 + // Returns true if the conversion succeeds. The conversion always succeeds
1.159 + // except when the input value is special and no infinity_symbol or
1.160 + // nan_symbol has been given to the constructor.
1.161 + bool ToShortest(double value, StringBuilder* result_builder) const {
1.162 + return ToShortestIeeeNumber(value, result_builder, SHORTEST);
1.163 + }
1.164 +
1.165 + // Same as ToShortest, but for single-precision floats.
1.166 + bool ToShortestSingle(float value, StringBuilder* result_builder) const {
1.167 + return ToShortestIeeeNumber(value, result_builder, SHORTEST_SINGLE);
1.168 + }
1.169 +
1.170 +
1.171 + // Computes a decimal representation with a fixed number of digits after the
1.172 + // decimal point. The last emitted digit is rounded.
1.173 + //
1.174 + // Examples:
1.175 + // ToFixed(3.12, 1) -> "3.1"
1.176 + // ToFixed(3.1415, 3) -> "3.142"
1.177 + // ToFixed(1234.56789, 4) -> "1234.5679"
1.178 + // ToFixed(1.23, 5) -> "1.23000"
1.179 + // ToFixed(0.1, 4) -> "0.1000"
1.180 + // ToFixed(1e30, 2) -> "1000000000000000019884624838656.00"
1.181 + // ToFixed(0.1, 30) -> "0.100000000000000005551115123126"
1.182 + // ToFixed(0.1, 17) -> "0.10000000000000001"
1.183 + //
1.184 + // If requested_digits equals 0, then the tail of the result depends on
1.185 + // the EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT.
1.186 + // Examples, for requested_digits == 0,
1.187 + // let EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT be
1.188 + // - false and false: then 123.45 -> 123
1.189 + // 0.678 -> 1
1.190 + // - true and false: then 123.45 -> 123.
1.191 + // 0.678 -> 1.
1.192 + // - true and true: then 123.45 -> 123.0
1.193 + // 0.678 -> 1.0
1.194 + //
1.195 + // Returns true if the conversion succeeds. The conversion always succeeds
1.196 + // except for the following cases:
1.197 + // - the input value is special and no infinity_symbol or nan_symbol has
1.198 + // been provided to the constructor,
1.199 + // - 'value' > 10^kMaxFixedDigitsBeforePoint, or
1.200 + // - 'requested_digits' > kMaxFixedDigitsAfterPoint.
1.201 + // The last two conditions imply that the result will never contain more than
1.202 + // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters
1.203 + // (one additional character for the sign, and one for the decimal point).
1.204 + MFBT_API bool ToFixed(double value,
1.205 + int requested_digits,
1.206 + StringBuilder* result_builder) const;
1.207 +
1.208 + // Computes a representation in exponential format with requested_digits
1.209 + // after the decimal point. The last emitted digit is rounded.
1.210 + // If requested_digits equals -1, then the shortest exponential representation
1.211 + // is computed.
1.212 + //
1.213 + // Examples with EMIT_POSITIVE_EXPONENT_SIGN deactivated, and
1.214 + // exponent_character set to 'e'.
1.215 + // ToExponential(3.12, 1) -> "3.1e0"
1.216 + // ToExponential(5.0, 3) -> "5.000e0"
1.217 + // ToExponential(0.001, 2) -> "1.00e-3"
1.218 + // ToExponential(3.1415, -1) -> "3.1415e0"
1.219 + // ToExponential(3.1415, 4) -> "3.1415e0"
1.220 + // ToExponential(3.1415, 3) -> "3.142e0"
1.221 + // ToExponential(123456789000000, 3) -> "1.235e14"
1.222 + // ToExponential(1000000000000000019884624838656.0, -1) -> "1e30"
1.223 + // ToExponential(1000000000000000019884624838656.0, 32) ->
1.224 + // "1.00000000000000001988462483865600e30"
1.225 + // ToExponential(1234, 0) -> "1e3"
1.226 + //
1.227 + // Returns true if the conversion succeeds. The conversion always succeeds
1.228 + // except for the following cases:
1.229 + // - the input value is special and no infinity_symbol or nan_symbol has
1.230 + // been provided to the constructor,
1.231 + // - 'requested_digits' > kMaxExponentialDigits.
1.232 + // The last condition implies that the result will never contain more than
1.233 + // kMaxExponentialDigits + 8 characters (the sign, the digit before the
1.234 + // decimal point, the decimal point, the exponent character, the
1.235 + // exponent's sign, and at most 3 exponent digits).
1.236 + MFBT_API bool ToExponential(double value,
1.237 + int requested_digits,
1.238 + StringBuilder* result_builder) const;
1.239 +
1.240 + // Computes 'precision' leading digits of the given 'value' and returns them
1.241 + // either in exponential or decimal format, depending on
1.242 + // max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the
1.243 + // constructor).
1.244 + // The last computed digit is rounded.
1.245 + //
1.246 + // Example with max_leading_padding_zeroes_in_precision_mode = 6.
1.247 + // ToPrecision(0.0000012345, 2) -> "0.0000012"
1.248 + // ToPrecision(0.00000012345, 2) -> "1.2e-7"
1.249 + // Similarily the converter may add up to
1.250 + // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid
1.251 + // returning an exponential representation. A zero added by the
1.252 + // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit.
1.253 + // Examples for max_trailing_padding_zeroes_in_precision_mode = 1:
1.254 + // ToPrecision(230.0, 2) -> "230"
1.255 + // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT.
1.256 + // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT.
1.257 + // Examples for max_trailing_padding_zeroes_in_precision_mode = 3, and no
1.258 + // EMIT_TRAILING_ZERO_AFTER_POINT:
1.259 + // ToPrecision(123450.0, 6) -> "123450"
1.260 + // ToPrecision(123450.0, 5) -> "123450"
1.261 + // ToPrecision(123450.0, 4) -> "123500"
1.262 + // ToPrecision(123450.0, 3) -> "123000"
1.263 + // ToPrecision(123450.0, 2) -> "1.2e5"
1.264 + //
1.265 + // Returns true if the conversion succeeds. The conversion always succeeds
1.266 + // except for the following cases:
1.267 + // - the input value is special and no infinity_symbol or nan_symbol has
1.268 + // been provided to the constructor,
1.269 + // - precision < kMinPericisionDigits
1.270 + // - precision > kMaxPrecisionDigits
1.271 + // The last condition implies that the result will never contain more than
1.272 + // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the
1.273 + // exponent character, the exponent's sign, and at most 3 exponent digits).
1.274 + MFBT_API bool ToPrecision(double value,
1.275 + int precision,
1.276 + bool* used_exponential_notation,
1.277 + StringBuilder* result_builder) const;
1.278 +
1.279 + enum DtoaMode {
1.280 + // Produce the shortest correct representation.
1.281 + // For example the output of 0.299999999999999988897 is (the less accurate
1.282 + // but correct) 0.3.
1.283 + SHORTEST,
1.284 + // Same as SHORTEST, but for single-precision floats.
1.285 + SHORTEST_SINGLE,
1.286 + // Produce a fixed number of digits after the decimal point.
1.287 + // For instance fixed(0.1, 4) becomes 0.1000
1.288 + // If the input number is big, the output will be big.
1.289 + FIXED,
1.290 + // Fixed number of digits (independent of the decimal point).
1.291 + PRECISION
1.292 + };
1.293 +
1.294 + // The maximal number of digits that are needed to emit a double in base 10.
1.295 + // A higher precision can be achieved by using more digits, but the shortest
1.296 + // accurate representation of any double will never use more digits than
1.297 + // kBase10MaximalLength.
1.298 + // Note that DoubleToAscii null-terminates its input. So the given buffer
1.299 + // should be at least kBase10MaximalLength + 1 characters long.
1.300 + static const MFBT_DATA int kBase10MaximalLength = 17;
1.301 +
1.302 + // Converts the given double 'v' to ascii. 'v' must not be NaN, +Infinity, or
1.303 + // -Infinity. In SHORTEST_SINGLE-mode this restriction also applies to 'v'
1.304 + // after it has been casted to a single-precision float. That is, in this
1.305 + // mode static_cast<float>(v) must not be NaN, +Infinity or -Infinity.
1.306 + //
1.307 + // The result should be interpreted as buffer * 10^(point-length).
1.308 + //
1.309 + // The output depends on the given mode:
1.310 + // - SHORTEST: produce the least amount of digits for which the internal
1.311 + // identity requirement is still satisfied. If the digits are printed
1.312 + // (together with the correct exponent) then reading this number will give
1.313 + // 'v' again. The buffer will choose the representation that is closest to
1.314 + // 'v'. If there are two at the same distance, than the one farther away
1.315 + // from 0 is chosen (halfway cases - ending with 5 - are rounded up).
1.316 + // In this mode the 'requested_digits' parameter is ignored.
1.317 + // - SHORTEST_SINGLE: same as SHORTEST but with single-precision.
1.318 + // - FIXED: produces digits necessary to print a given number with
1.319 + // 'requested_digits' digits after the decimal point. The produced digits
1.320 + // might be too short in which case the caller has to fill the remainder
1.321 + // with '0's.
1.322 + // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2.
1.323 + // Halfway cases are rounded towards +/-Infinity (away from 0). The call
1.324 + // toFixed(0.15, 2) thus returns buffer="2", point=0.
1.325 + // The returned buffer may contain digits that would be truncated from the
1.326 + // shortest representation of the input.
1.327 + // - PRECISION: produces 'requested_digits' where the first digit is not '0'.
1.328 + // Even though the length of produced digits usually equals
1.329 + // 'requested_digits', the function is allowed to return fewer digits, in
1.330 + // which case the caller has to fill the missing digits with '0's.
1.331 + // Halfway cases are again rounded away from 0.
1.332 + // DoubleToAscii expects the given buffer to be big enough to hold all
1.333 + // digits and a terminating null-character. In SHORTEST-mode it expects a
1.334 + // buffer of at least kBase10MaximalLength + 1. In all other modes the
1.335 + // requested_digits parameter and the padding-zeroes limit the size of the
1.336 + // output. Don't forget the decimal point, the exponent character and the
1.337 + // terminating null-character when computing the maximal output size.
1.338 + // The given length is only used in debug mode to ensure the buffer is big
1.339 + // enough.
1.340 + static MFBT_API void DoubleToAscii(double v,
1.341 + DtoaMode mode,
1.342 + int requested_digits,
1.343 + char* buffer,
1.344 + int buffer_length,
1.345 + bool* sign,
1.346 + int* length,
1.347 + int* point);
1.348 +
1.349 + private:
1.350 + // Implementation for ToShortest and ToShortestSingle.
1.351 + MFBT_API bool ToShortestIeeeNumber(double value,
1.352 + StringBuilder* result_builder,
1.353 + DtoaMode mode) const;
1.354 +
1.355 + // If the value is a special value (NaN or Infinity) constructs the
1.356 + // corresponding string using the configured infinity/nan-symbol.
1.357 + // If either of them is NULL or the value is not special then the
1.358 + // function returns false.
1.359 + MFBT_API bool HandleSpecialValues(double value, StringBuilder* result_builder) const;
1.360 + // Constructs an exponential representation (i.e. 1.234e56).
1.361 + // The given exponent assumes a decimal point after the first decimal digit.
1.362 + MFBT_API void CreateExponentialRepresentation(const char* decimal_digits,
1.363 + int length,
1.364 + int exponent,
1.365 + StringBuilder* result_builder) const;
1.366 + // Creates a decimal representation (i.e 1234.5678).
1.367 + MFBT_API void CreateDecimalRepresentation(const char* decimal_digits,
1.368 + int length,
1.369 + int decimal_point,
1.370 + int digits_after_point,
1.371 + StringBuilder* result_builder) const;
1.372 +
1.373 + const int flags_;
1.374 + const char* const infinity_symbol_;
1.375 + const char* const nan_symbol_;
1.376 + const char exponent_character_;
1.377 + const int decimal_in_shortest_low_;
1.378 + const int decimal_in_shortest_high_;
1.379 + const int max_leading_padding_zeroes_in_precision_mode_;
1.380 + const int max_trailing_padding_zeroes_in_precision_mode_;
1.381 +
1.382 + DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter);
1.383 +};
1.384 +
1.385 +
1.386 +class StringToDoubleConverter {
1.387 + public:
1.388 + // Enumeration for allowing octals and ignoring junk when converting
1.389 + // strings to numbers.
1.390 + enum Flags {
1.391 + NO_FLAGS = 0,
1.392 + ALLOW_HEX = 1,
1.393 + ALLOW_OCTALS = 2,
1.394 + ALLOW_TRAILING_JUNK = 4,
1.395 + ALLOW_LEADING_SPACES = 8,
1.396 + ALLOW_TRAILING_SPACES = 16,
1.397 + ALLOW_SPACES_AFTER_SIGN = 32
1.398 + };
1.399 +
1.400 + // Flags should be a bit-or combination of the possible Flags-enum.
1.401 + // - NO_FLAGS: no special flags.
1.402 + // - ALLOW_HEX: recognizes the prefix "0x". Hex numbers may only be integers.
1.403 + // Ex: StringToDouble("0x1234") -> 4660.0
1.404 + // In StringToDouble("0x1234.56") the characters ".56" are trailing
1.405 + // junk. The result of the call is hence dependent on
1.406 + // the ALLOW_TRAILING_JUNK flag and/or the junk value.
1.407 + // With this flag "0x" is a junk-string. Even with ALLOW_TRAILING_JUNK,
1.408 + // the string will not be parsed as "0" followed by junk.
1.409 + //
1.410 + // - ALLOW_OCTALS: recognizes the prefix "0" for octals:
1.411 + // If a sequence of octal digits starts with '0', then the number is
1.412 + // read as octal integer. Octal numbers may only be integers.
1.413 + // Ex: StringToDouble("01234") -> 668.0
1.414 + // StringToDouble("012349") -> 12349.0 // Not a sequence of octal
1.415 + // // digits.
1.416 + // In StringToDouble("01234.56") the characters ".56" are trailing
1.417 + // junk. The result of the call is hence dependent on
1.418 + // the ALLOW_TRAILING_JUNK flag and/or the junk value.
1.419 + // In StringToDouble("01234e56") the characters "e56" are trailing
1.420 + // junk, too.
1.421 + // - ALLOW_TRAILING_JUNK: ignore trailing characters that are not part of
1.422 + // a double literal.
1.423 + // - ALLOW_LEADING_SPACES: skip over leading spaces.
1.424 + // - ALLOW_TRAILING_SPACES: ignore trailing spaces.
1.425 + // - ALLOW_SPACES_AFTER_SIGN: ignore spaces after the sign.
1.426 + // Ex: StringToDouble("- 123.2") -> -123.2.
1.427 + // StringToDouble("+ 123.2") -> 123.2
1.428 + //
1.429 + // empty_string_value is returned when an empty string is given as input.
1.430 + // If ALLOW_LEADING_SPACES or ALLOW_TRAILING_SPACES are set, then a string
1.431 + // containing only spaces is converted to the 'empty_string_value', too.
1.432 + //
1.433 + // junk_string_value is returned when
1.434 + // a) ALLOW_TRAILING_JUNK is not set, and a junk character (a character not
1.435 + // part of a double-literal) is found.
1.436 + // b) ALLOW_TRAILING_JUNK is set, but the string does not start with a
1.437 + // double literal.
1.438 + //
1.439 + // infinity_symbol and nan_symbol are strings that are used to detect
1.440 + // inputs that represent infinity and NaN. They can be null, in which case
1.441 + // they are ignored.
1.442 + // The conversion routine first reads any possible signs. Then it compares the
1.443 + // following character of the input-string with the first character of
1.444 + // the infinity, and nan-symbol. If either matches, the function assumes, that
1.445 + // a match has been found, and expects the following input characters to match
1.446 + // the remaining characters of the special-value symbol.
1.447 + // This means that the following restrictions apply to special-value symbols:
1.448 + // - they must not start with signs ('+', or '-'),
1.449 + // - they must not have the same first character.
1.450 + // - they must not start with digits.
1.451 + //
1.452 + // Examples:
1.453 + // flags = ALLOW_HEX | ALLOW_TRAILING_JUNK,
1.454 + // empty_string_value = 0.0,
1.455 + // junk_string_value = NaN,
1.456 + // infinity_symbol = "infinity",
1.457 + // nan_symbol = "nan":
1.458 + // StringToDouble("0x1234") -> 4660.0.
1.459 + // StringToDouble("0x1234K") -> 4660.0.
1.460 + // StringToDouble("") -> 0.0 // empty_string_value.
1.461 + // StringToDouble(" ") -> NaN // junk_string_value.
1.462 + // StringToDouble(" 1") -> NaN // junk_string_value.
1.463 + // StringToDouble("0x") -> NaN // junk_string_value.
1.464 + // StringToDouble("-123.45") -> -123.45.
1.465 + // StringToDouble("--123.45") -> NaN // junk_string_value.
1.466 + // StringToDouble("123e45") -> 123e45.
1.467 + // StringToDouble("123E45") -> 123e45.
1.468 + // StringToDouble("123e+45") -> 123e45.
1.469 + // StringToDouble("123E-45") -> 123e-45.
1.470 + // StringToDouble("123e") -> 123.0 // trailing junk ignored.
1.471 + // StringToDouble("123e-") -> 123.0 // trailing junk ignored.
1.472 + // StringToDouble("+NaN") -> NaN // NaN string literal.
1.473 + // StringToDouble("-infinity") -> -inf. // infinity literal.
1.474 + // StringToDouble("Infinity") -> NaN // junk_string_value.
1.475 + //
1.476 + // flags = ALLOW_OCTAL | ALLOW_LEADING_SPACES,
1.477 + // empty_string_value = 0.0,
1.478 + // junk_string_value = NaN,
1.479 + // infinity_symbol = NULL,
1.480 + // nan_symbol = NULL:
1.481 + // StringToDouble("0x1234") -> NaN // junk_string_value.
1.482 + // StringToDouble("01234") -> 668.0.
1.483 + // StringToDouble("") -> 0.0 // empty_string_value.
1.484 + // StringToDouble(" ") -> 0.0 // empty_string_value.
1.485 + // StringToDouble(" 1") -> 1.0
1.486 + // StringToDouble("0x") -> NaN // junk_string_value.
1.487 + // StringToDouble("0123e45") -> NaN // junk_string_value.
1.488 + // StringToDouble("01239E45") -> 1239e45.
1.489 + // StringToDouble("-infinity") -> NaN // junk_string_value.
1.490 + // StringToDouble("NaN") -> NaN // junk_string_value.
1.491 + StringToDoubleConverter(int flags,
1.492 + double empty_string_value,
1.493 + double junk_string_value,
1.494 + const char* infinity_symbol,
1.495 + const char* nan_symbol)
1.496 + : flags_(flags),
1.497 + empty_string_value_(empty_string_value),
1.498 + junk_string_value_(junk_string_value),
1.499 + infinity_symbol_(infinity_symbol),
1.500 + nan_symbol_(nan_symbol) {
1.501 + }
1.502 +
1.503 + // Performs the conversion.
1.504 + // The output parameter 'processed_characters_count' is set to the number
1.505 + // of characters that have been processed to read the number.
1.506 + // Spaces than are processed with ALLOW_{LEADING|TRAILING}_SPACES are included
1.507 + // in the 'processed_characters_count'. Trailing junk is never included.
1.508 + double StringToDouble(const char* buffer,
1.509 + int length,
1.510 + int* processed_characters_count) const {
1.511 + return StringToIeee(buffer, length, processed_characters_count, true);
1.512 + }
1.513 +
1.514 + // Same as StringToDouble but reads a float.
1.515 + // Note that this is not equivalent to static_cast<float>(StringToDouble(...))
1.516 + // due to potential double-rounding.
1.517 + float StringToFloat(const char* buffer,
1.518 + int length,
1.519 + int* processed_characters_count) const {
1.520 + return static_cast<float>(StringToIeee(buffer, length,
1.521 + processed_characters_count, false));
1.522 + }
1.523 +
1.524 + private:
1.525 + const int flags_;
1.526 + const double empty_string_value_;
1.527 + const double junk_string_value_;
1.528 + const char* const infinity_symbol_;
1.529 + const char* const nan_symbol_;
1.530 +
1.531 + double StringToIeee(const char* buffer,
1.532 + int length,
1.533 + int* processed_characters_count,
1.534 + bool read_as_double) const;
1.535 +
1.536 + DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter);
1.537 +};
1.538 +
1.539 +} // namespace double_conversion
1.540 +
1.541 +#endif // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_
