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| 1 // Copyright 2010 the V8 project authors. All rights reserved. | |
| 2 // Redistribution and use in source and binary forms, with or without | |
| 3 // modification, are permitted provided that the following conditions are | |
| 4 // met: | |
| 5 // | |
| 6 // * Redistributions of source code must retain the above copyright | |
| 7 // notice, this list of conditions and the following disclaimer. | |
| 8 // * Redistributions in binary form must reproduce the above | |
| 9 // copyright notice, this list of conditions and the following | |
| 10 // disclaimer in the documentation and/or other materials provided | |
| 11 // with the distribution. | |
| 12 // * Neither the name of Google Inc. nor the names of its | |
| 13 // contributors may be used to endorse or promote products derived | |
| 14 // from this software without specific prior written permission. | |
| 15 // | |
| 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 27 | |
| 28 #ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ | |
| 29 #define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ | |
| 30 | |
| 31 #include <wtf/dtoa/utils.h> | |
| 32 | |
| 33 namespace WTF { | |
| 34 | |
| 35 namespace double_conversion { | |
| 36 | |
| 37 class DoubleToStringConverter { | |
| 38 public: | |
| 39 // When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint | |
| 40 // or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the | |
| 41 // function returns false. | |
| 42 static const int kMaxFixedDigitsBeforePoint = 60; | |
| 43 static const int kMaxFixedDigitsAfterPoint = 60; | |
| 44 | |
| 45 // When calling ToExponential with a requested_digits | |
| 46 // parameter > kMaxExponentialDigits then the function returns false. | |
| 47 static const int kMaxExponentialDigits = 120; | |
| 48 | |
| 49 // When calling ToPrecision with a requested_digits | |
| 50 // parameter < kMinPrecisionDigits or requested_digits > kMaxPrecisionDi
gits | |
| 51 // then the function returns false. | |
| 52 static const int kMinPrecisionDigits = 1; | |
| 53 static const int kMaxPrecisionDigits = 120; | |
| 54 | |
| 55 enum Flags { | |
| 56 NO_FLAGS = 0, | |
| 57 EMIT_POSITIVE_EXPONENT_SIGN = 1, | |
| 58 EMIT_TRAILING_DECIMAL_POINT = 2, | |
| 59 EMIT_TRAILING_ZERO_AFTER_POINT = 4, | |
| 60 UNIQUE_ZERO = 8 | |
| 61 }; | |
| 62 | |
| 63 // Flags should be a bit-or combination of the possible Flags-enum. | |
| 64 // - NO_FLAGS: no special flags. | |
| 65 // - EMIT_POSITIVE_EXPONENT_SIGN: when the number is converted into exp
onent | |
| 66 // form, emits a '+' for positive exponents. Example: 1.2e+2. | |
| 67 // - EMIT_TRAILING_DECIMAL_POINT: when the input number is an integer a
nd is | |
| 68 // converted into decimal format then a trailing decimal point is app
ended. | |
| 69 // Example: 2345.0 is converted to "2345.". | |
| 70 // - EMIT_TRAILING_ZERO_AFTER_POINT: in addition to a trailing decimal
point | |
| 71 // emits a trailing '0'-character. This flag requires the | |
| 72 // EXMIT_TRAILING_DECIMAL_POINT flag. | |
| 73 // Example: 2345.0 is converted to "2345.0". | |
| 74 // - UNIQUE_ZERO: "-0.0" is converted to "0.0". | |
| 75 // | |
| 76 // Infinity symbol and nan_symbol provide the string representation for
these | |
| 77 // special values. If the string is NULL and the special value is encoun
tered | |
| 78 // then the conversion functions return false. | |
| 79 // | |
| 80 // The exponent_character is used in exponential representations. It is | |
| 81 // usually 'e' or 'E'. | |
| 82 // | |
| 83 // When converting to the shortest representation the converter will | |
| 84 // represent input numbers in decimal format if they are in the interval | |
| 85 // [10^decimal_in_shortest_low; 10^decimal_in_shortest_high[ | |
| 86 // (lower boundary included, greater boundary excluded). | |
| 87 // Example: with decimal_in_shortest_low = -6 and | |
| 88 // decimal_in_shortest_high = 21: | |
| 89 // ToShortest(0.000001) -> "0.000001" | |
| 90 // ToShortest(0.0000001) -> "1e-7" | |
| 91 // ToShortest(111111111111111111111.0) -> "111111111111111110000" | |
| 92 // ToShortest(100000000000000000000.0) -> "100000000000000000000" | |
| 93 // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21" | |
| 94 // | |
| 95 // When converting to precision mode the converter may add | |
| 96 // max_leading_padding_zeroes before returning the number in exponential | |
| 97 // format. | |
| 98 // Example with max_leading_padding_zeroes_in_precision_mode = 6. | |
| 99 // ToPrecision(0.0000012345, 2) -> "0.0000012" | |
| 100 // ToPrecision(0.00000012345, 2) -> "1.2e-7" | |
| 101 // Similarily the converter may add up to | |
| 102 // max_trailing_padding_zeroes_in_precision_mode in precision mode to av
oid | |
| 103 // returning an exponential representation. A zero added by the | |
| 104 // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit. | |
| 105 // Examples for max_trailing_padding_zeroes_in_precision_mode = 1: | |
| 106 // ToPrecision(230.0, 2) -> "230" | |
| 107 // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT. | |
| 108 // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POIN
T. | |
| 109 DoubleToStringConverter(int flags, | |
| 110 const char* infinity_symbol, | |
| 111 const char* nan_symbol, | |
| 112 char exponent_character, | |
| 113 int decimal_in_shortest_low, | |
| 114 int decimal_in_shortest_high, | |
| 115 int max_leading_padding_zeroes_in_precision_mode
, | |
| 116 int max_trailing_padding_zeroes_in_precision_mod
e) | |
| 117 : flags_(flags), | |
| 118 infinity_symbol_(infinity_symbol), | |
| 119 nan_symbol_(nan_symbol), | |
| 120 exponent_character_(exponent_character), | |
| 121 decimal_in_shortest_low_(decimal_in_shortest_low), | |
| 122 decimal_in_shortest_high_(decimal_in_shortest_high), | |
| 123 max_leading_padding_zeroes_in_precision_mode_( | |
| 124 max_leading_padding_zeroes
_in_precision_mode), | |
| 125 max_trailing_padding_zeroes_in_precision_mode_( | |
| 126 max_trailing_padding_zero
es_in_precision_mode) { | |
| 127 // When 'trailing zero after the point' is set, then 'trailing point
' | |
| 128 // must be set too. | |
| 129 ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) || | |
| 130 !((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0)); | |
| 131 } | |
| 132 | |
| 133 // Returns a converter following the EcmaScript specification. | |
| 134 static const DoubleToStringConverter& EcmaScriptConverter(); | |
| 135 | |
| 136 // Computes the shortest string of digits that correctly represent the i
nput | |
| 137 // number. Depending on decimal_in_shortest_low and decimal_in_shortest_
high | |
| 138 // (see constructor) it then either returns a decimal representation, or
an | |
| 139 // exponential representation. | |
| 140 // Example with decimal_in_shortest_low = -6, | |
| 141 // decimal_in_shortest_high = 21, | |
| 142 // EMIT_POSITIVE_EXPONENT_SIGN activated, and | |
| 143 // EMIT_TRAILING_DECIMAL_POINT deactived: | |
| 144 // ToShortest(0.000001) -> "0.000001" | |
| 145 // ToShortest(0.0000001) -> "1e-7" | |
| 146 // ToShortest(111111111111111111111.0) -> "111111111111111110000" | |
| 147 // ToShortest(100000000000000000000.0) -> "100000000000000000000" | |
| 148 // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21" | |
| 149 // | |
| 150 // Note: the conversion may round the output if the returned string | |
| 151 // is accurate enough to uniquely identify the input-number. | |
| 152 // For example the most precise representation of the double 9e59 equals | |
| 153 // "899999999999999918767229449717619953810131273674690656206848", but | |
| 154 // the converter will return the shorter (but still correct) "9e59". | |
| 155 // | |
| 156 // Returns true if the conversion succeeds. The conversion always succee
ds | |
| 157 // except when the input value is special and no infinity_symbol or | |
| 158 // nan_symbol has been given to the constructor. | |
| 159 bool ToShortest(double value, StringBuilder* result_builder) const; | |
| 160 | |
| 161 | |
| 162 // Computes a decimal representation with a fixed number of digits after
the | |
| 163 // decimal point. The last emitted digit is rounded. | |
| 164 // | |
| 165 // Examples: | |
| 166 // ToFixed(3.12, 1) -> "3.1" | |
| 167 // ToFixed(3.1415, 3) -> "3.142" | |
| 168 // ToFixed(1234.56789, 4) -> "1234.5679" | |
| 169 // ToFixed(1.23, 5) -> "1.23000" | |
| 170 // ToFixed(0.1, 4) -> "0.1000" | |
| 171 // ToFixed(1e30, 2) -> "1000000000000000019884624838656.00" | |
| 172 // ToFixed(0.1, 30) -> "0.100000000000000005551115123126" | |
| 173 // ToFixed(0.1, 17) -> "0.10000000000000001" | |
| 174 // | |
| 175 // If requested_digits equals 0, then the tail of the result depends on | |
| 176 // the EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT. | |
| 177 // Examples, for requested_digits == 0, | |
| 178 // let EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT
be | |
| 179 // - false and false: then 123.45 -> 123 | |
| 180 // 0.678 -> 1 | |
| 181 // - true and false: then 123.45 -> 123. | |
| 182 // 0.678 -> 1. | |
| 183 // - true and true: then 123.45 -> 123.0 | |
| 184 // 0.678 -> 1.0 | |
| 185 // | |
| 186 // Returns true if the conversion succeeds. The conversion always succee
ds | |
| 187 // except for the following cases: | |
| 188 // - the input value is special and no infinity_symbol or nan_symbol h
as | |
| 189 // been provided to the constructor, | |
| 190 // - 'value' > 10^kMaxFixedDigitsBeforePoint, or | |
| 191 // - 'requested_digits' > kMaxFixedDigitsAfterPoint. | |
| 192 // The last two conditions imply that the result will never contain more
than | |
| 193 // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint charac
ters | |
| 194 // (one additional character for the sign, and one for the decimal point
). | |
| 195 bool ToFixed(double value, | |
| 196 int requested_digits, | |
| 197 StringBuilder* result_builder) const; | |
| 198 | |
| 199 // Computes a representation in exponential format with requested_digits | |
| 200 // after the decimal point. The last emitted digit is rounded. | |
| 201 // If requested_digits equals -1, then the shortest exponential represen
tation | |
| 202 // is computed. | |
| 203 // | |
| 204 // Examples with EMIT_POSITIVE_EXPONENT_SIGN deactivated, and | |
| 205 // exponent_character set to 'e'. | |
| 206 // ToExponential(3.12, 1) -> "3.1e0" | |
| 207 // ToExponential(5.0, 3) -> "5.000e0" | |
| 208 // ToExponential(0.001, 2) -> "1.00e-3" | |
| 209 // ToExponential(3.1415, -1) -> "3.1415e0" | |
| 210 // ToExponential(3.1415, 4) -> "3.1415e0" | |
| 211 // ToExponential(3.1415, 3) -> "3.142e0" | |
| 212 // ToExponential(123456789000000, 3) -> "1.235e14" | |
| 213 // ToExponential(1000000000000000019884624838656.0, -1) -> "1e30" | |
| 214 // ToExponential(1000000000000000019884624838656.0, 32) -> | |
| 215 // "1.00000000000000001988462483865600e30" | |
| 216 // ToExponential(1234, 0) -> "1e3" | |
| 217 // | |
| 218 // Returns true if the conversion succeeds. The conversion always succee
ds | |
| 219 // except for the following cases: | |
| 220 // - the input value is special and no infinity_symbol or nan_symbol h
as | |
| 221 // been provided to the constructor, | |
| 222 // - 'requested_digits' > kMaxExponentialDigits. | |
| 223 // The last condition implies that the result will never contain more th
an | |
| 224 // kMaxExponentialDigits + 8 characters (the sign, the digit before the | |
| 225 // decimal point, the decimal point, the exponent character, the | |
| 226 // exponent's sign, and at most 3 exponent digits). | |
| 227 bool ToExponential(double value, | |
| 228 int requested_digits, | |
| 229 StringBuilder* result_builder) const; | |
| 230 | |
| 231 // Computes 'precision' leading digits of the given 'value' and returns
them | |
| 232 // either in exponential or decimal format, depending on | |
| 233 // max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the | |
| 234 // constructor). | |
| 235 // The last computed digit is rounded. | |
| 236 // | |
| 237 // Example with max_leading_padding_zeroes_in_precision_mode = 6. | |
| 238 // ToPrecision(0.0000012345, 2) -> "0.0000012" | |
| 239 // ToPrecision(0.00000012345, 2) -> "1.2e-7" | |
| 240 // Similarily the converter may add up to | |
| 241 // max_trailing_padding_zeroes_in_precision_mode in precision mode to av
oid | |
| 242 // returning an exponential representation. A zero added by the | |
| 243 // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit. | |
| 244 // Examples for max_trailing_padding_zeroes_in_precision_mode = 1: | |
| 245 // ToPrecision(230.0, 2) -> "230" | |
| 246 // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT. | |
| 247 // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POIN
T. | |
| 248 // Examples for max_trailing_padding_zeroes_in_precision_mode = 3, and n
o | |
| 249 // EMIT_TRAILING_ZERO_AFTER_POINT: | |
| 250 // ToPrecision(123450.0, 6) -> "123450" | |
| 251 // ToPrecision(123450.0, 5) -> "123450" | |
| 252 // ToPrecision(123450.0, 4) -> "123500" | |
| 253 // ToPrecision(123450.0, 3) -> "123000" | |
| 254 // ToPrecision(123450.0, 2) -> "1.2e5" | |
| 255 // | |
| 256 // Returns true if the conversion succeeds. The conversion always succee
ds | |
| 257 // except for the following cases: | |
| 258 // - the input value is special and no infinity_symbol or nan_symbol h
as | |
| 259 // been provided to the constructor, | |
| 260 // - precision < kMinPericisionDigits | |
| 261 // - precision > kMaxPrecisionDigits | |
| 262 // The last condition implies that the result will never contain more th
an | |
| 263 // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the | |
| 264 // exponent character, the exponent's sign, and at most 3 exponent digit
s). | |
| 265 bool ToPrecision(double value, | |
| 266 int precision, | |
| 267 StringBuilder* result_builder) const; | |
| 268 | |
| 269 enum DtoaMode { | |
| 270 // Produce the shortest correct representation. | |
| 271 // For example the output of 0.299999999999999988897 is (the less ac
curate | |
| 272 // but correct) 0.3. | |
| 273 SHORTEST, | |
| 274 // Produce a fixed number of digits after the decimal point. | |
| 275 // For instance fixed(0.1, 4) becomes 0.1000 | |
| 276 // If the input number is big, the output will be big. | |
| 277 FIXED, | |
| 278 // Fixed number of digits (independent of the decimal point). | |
| 279 PRECISION | |
| 280 }; | |
| 281 | |
| 282 // The maximal number of digits that are needed to emit a double in base
10. | |
| 283 // A higher precision can be achieved by using more digits, but the shor
test | |
| 284 // accurate representation of any double will never use more digits than | |
| 285 // kBase10MaximalLength. | |
| 286 // Note that DoubleToAscii null-terminates its input. So the given buffe
r | |
| 287 // should be at least kBase10MaximalLength + 1 characters long. | |
| 288 static const int kBase10MaximalLength = 17; | |
| 289 | |
| 290 // Converts the given double 'v' to ascii. | |
| 291 // The result should be interpreted as buffer * 10^(point-length). | |
| 292 // | |
| 293 // The output depends on the given mode: | |
| 294 // - SHORTEST: produce the least amount of digits for which the interna
l | |
| 295 // identity requirement is still satisfied. If the digits are printed | |
| 296 // (together with the correct exponent) then reading this number will
give | |
| 297 // 'v' again. The buffer will choose the representation that is closes
t to | |
| 298 // 'v'. If there are two at the same distance, than the one farther aw
ay | |
| 299 // from 0 is chosen (halfway cases - ending with 5 - are rounded up). | |
| 300 // In this mode the 'requested_digits' parameter is ignored. | |
| 301 // - FIXED: produces digits necessary to print a given number with | |
| 302 // 'requested_digits' digits after the decimal point. The produced dig
its | |
| 303 // might be too short in which case the caller has to fill the remaind
er | |
| 304 // with '0's. | |
| 305 // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-
2. | |
| 306 // Halfway cases are rounded towards +/-Infinity (away from 0). The ca
ll | |
| 307 // toFixed(0.15, 2) thus returns buffer="2", point=0. | |
| 308 // The returned buffer may contain digits that would be truncated from
the | |
| 309 // shortest representation of the input. | |
| 310 // - PRECISION: produces 'requested_digits' where the first digit is no
t '0'. | |
| 311 // Even though the length of produced digits usually equals | |
| 312 // 'requested_digits', the function is allowed to return fewer digits,
in | |
| 313 // which case the caller has to fill the missing digits with '0's. | |
| 314 // Halfway cases are again rounded away from 0. | |
| 315 // DoubleToAscii expects the given buffer to be big enough to hold all | |
| 316 // digits and a terminating null-character. In SHORTEST-mode it expects
a | |
| 317 // buffer of at least kBase10MaximalLength + 1. In all other modes the | |
| 318 // requested_digits parameter (+ 1 for the null-character) limits the si
ze of | |
| 319 // the output. The given length is only used in debug mode to ensure the | |
| 320 // buffer is big enough. | |
| 321 static void DoubleToAscii(double v, | |
| 322 DtoaMode mode, | |
| 323 int requested_digits, | |
| 324 char* buffer, | |
| 325 int buffer_length, | |
| 326 bool* sign, | |
| 327 int* length, | |
| 328 int* point); | |
| 329 | |
| 330 private: | |
| 331 // If the value is a special value (NaN or Infinity) constructs the | |
| 332 // corresponding string using the configured infinity/nan-symbol. | |
| 333 // If either of them is NULL or the value is not special then the | |
| 334 // function returns false. | |
| 335 bool HandleSpecialValues(double value, StringBuilder* result_builder) co
nst; | |
| 336 // Constructs an exponential representation (i.e. 1.234e56). | |
| 337 // The given exponent assumes a decimal point after the first decimal di
git. | |
| 338 void CreateExponentialRepresentation(const char* decimal_digits, | |
| 339 int length, | |
| 340 int exponent, | |
| 341 StringBuilder* result_builder) cons
t; | |
| 342 // Creates a decimal representation (i.e 1234.5678). | |
| 343 void CreateDecimalRepresentation(const char* decimal_digits, | |
| 344 int length, | |
| 345 int decimal_point, | |
| 346 int digits_after_point, | |
| 347 StringBuilder* result_builder) const; | |
| 348 | |
| 349 const int flags_; | |
| 350 const char* const infinity_symbol_; | |
| 351 const char* const nan_symbol_; | |
| 352 const char exponent_character_; | |
| 353 const int decimal_in_shortest_low_; | |
| 354 const int decimal_in_shortest_high_; | |
| 355 const int max_leading_padding_zeroes_in_precision_mode_; | |
| 356 const int max_trailing_padding_zeroes_in_precision_mode_; | |
| 357 | |
| 358 DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter); | |
| 359 }; | |
| 360 | |
| 361 | |
| 362 class StringToDoubleConverter { | |
| 363 public: | |
| 364 // Performs the conversion. | |
| 365 // The output parameter 'processed_characters_count' is set to the numbe
r | |
| 366 // of characters that have been processed to read the number. | |
| 367 WTF_EXPORT_PRIVATE static double StringToDouble(const char* buffer, size
_t length, size_t* processed_characters_count); | |
| 368 | |
| 369 private: | |
| 370 DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter); | |
| 371 }; | |
| 372 | |
| 373 } // namespace double_conversion | |
| 374 | |
| 375 } // namespace WTF | |
| 376 | |
| 377 #endif // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ | |
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