| 1 | // Copyright 2012 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 |
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| 5 | // |
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| 27 | |
| 28 | #ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ |
| 29 | #define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ |
| 30 | |
| 31 | #include "utils.h" |
| 32 | |
| 33 | namespace double_conversion { |
| 34 | |
| 35 | class DoubleToStringConverter { |
| 36 | public: |
| 37 | // When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint |
| 38 | // or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the |
| 39 | // function returns false. |
| 40 | static const int kMaxFixedDigitsBeforePoint = 60; |
| 41 | static const int kMaxFixedDigitsAfterPoint = 60; |
| 42 | |
| 43 | // When calling ToExponential with a requested_digits |
| 44 | // parameter > kMaxExponentialDigits then the function returns false. |
| 45 | static const int kMaxExponentialDigits = 120; |
| 46 | |
| 47 | // When calling ToPrecision with a requested_digits |
| 48 | // parameter < kMinPrecisionDigits or requested_digits > kMaxPrecisionDigits |
| 49 | // then the function returns false. |
| 50 | static const int kMinPrecisionDigits = 1; |
| 51 | static const int kMaxPrecisionDigits = 120; |
| 52 | |
| 53 | enum Flags { |
| 54 | NO_FLAGS = 0, |
| 55 | EMIT_POSITIVE_EXPONENT_SIGN = 1, |
| 56 | EMIT_TRAILING_DECIMAL_POINT = 2, |
| 57 | EMIT_TRAILING_ZERO_AFTER_POINT = 4, |
| 58 | UNIQUE_ZERO = 8 |
| 59 | }; |
| 60 | |
| 61 | // Flags should be a bit-or combination of the possible Flags-enum. |
| 62 | // - NO_FLAGS: no special flags. |
| 63 | // - EMIT_POSITIVE_EXPONENT_SIGN: when the number is converted into exponent |
| 64 | // form, emits a '+' for positive exponents. Example: 1.2e+2. |
| 65 | // - EMIT_TRAILING_DECIMAL_POINT: when the input number is an integer and is |
| 66 | // converted into decimal format then a trailing decimal point is appended. |
| 67 | // Example: 2345.0 is converted to "2345.". |
| 68 | // - EMIT_TRAILING_ZERO_AFTER_POINT: in addition to a trailing decimal point |
| 69 | // emits a trailing '0'-character. This flag requires the |
| 70 | // EXMIT_TRAILING_DECIMAL_POINT flag. |
| 71 | // Example: 2345.0 is converted to "2345.0". |
| 72 | // - UNIQUE_ZERO: "-0.0" is converted to "0.0". |
| 73 | // |
| 74 | // Infinity symbol and nan_symbol provide the string representation for these |
| 75 | // special values. If the string is NULL and the special value is encountered |
| 76 | // then the conversion functions return false. |
| 77 | // |
| 78 | // The exponent_character is used in exponential representations. It is |
| 79 | // usually 'e' or 'E'. |
| 80 | // |
| 81 | // When converting to the shortest representation the converter will |
| 82 | // represent input numbers in decimal format if they are in the interval |
| 83 | // [10^decimal_in_shortest_low; 10^decimal_in_shortest_high[ |
| 84 | // (lower boundary included, greater boundary excluded). |
| 85 | // Example: with decimal_in_shortest_low = -6 and |
| 86 | // decimal_in_shortest_high = 21: |
| 87 | // ToShortest(0.000001) -> "0.000001" |
| 88 | // ToShortest(0.0000001) -> "1e-7" |
| 89 | // ToShortest(111111111111111111111.0) -> "111111111111111110000" |
| 90 | // ToShortest(100000000000000000000.0) -> "100000000000000000000" |
| 91 | // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21" |
| 92 | // |
| 93 | // When converting to precision mode the converter may add |
| 94 | // max_leading_padding_zeroes before returning the number in exponential |
| 95 | // format. |
| 96 | // Example with max_leading_padding_zeroes_in_precision_mode = 6. |
| 97 | // ToPrecision(0.0000012345, 2) -> "0.0000012" |
| 98 | // ToPrecision(0.00000012345, 2) -> "1.2e-7" |
| 99 | // Similarily the converter may add up to |
| 100 | // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid |
| 101 | // returning an exponential representation. A zero added by the |
| 102 | // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit. |
| 103 | // Examples for max_trailing_padding_zeroes_in_precision_mode = 1: |
| 104 | // ToPrecision(230.0, 2) -> "230" |
| 105 | // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT. |
| 106 | // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT. |
| 107 | DoubleToStringConverter(int flags, |
| 108 | const char* infinity_symbol, |
| 109 | const char* nan_symbol, |
| 110 | char exponent_character, |
| 111 | int decimal_in_shortest_low, |
| 112 | int decimal_in_shortest_high, |
| 113 | int max_leading_padding_zeroes_in_precision_mode, |
| 114 | int max_trailing_padding_zeroes_in_precision_mode) |
| 115 | : flags_(flags), |
| 116 | infinity_symbol_(infinity_symbol), |
| 117 | nan_symbol_(nan_symbol), |
| 118 | exponent_character_(exponent_character), |
| 119 | decimal_in_shortest_low_(decimal_in_shortest_low), |
| 120 | decimal_in_shortest_high_(decimal_in_shortest_high), |
| 121 | max_leading_padding_zeroes_in_precision_mode_( |
| 122 | max_leading_padding_zeroes_in_precision_mode), |
| 123 | max_trailing_padding_zeroes_in_precision_mode_( |
| 124 | max_trailing_padding_zeroes_in_precision_mode) { |
| 125 | // When 'trailing zero after the point' is set, then 'trailing point' |
| 126 | // must be set too. |
| 127 | ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) || |
| 128 | !((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0)); |
| 129 | } |
| 130 | |
| 131 | // Returns a converter following the EcmaScript specification. |
| 132 | static const DoubleToStringConverter& EcmaScriptConverter(); |
| 133 | |
| 134 | // Computes the shortest string of digits that correctly represent the input |
| 135 | // number. Depending on decimal_in_shortest_low and decimal_in_shortest_high |
| 136 | // (see constructor) it then either returns a decimal representation, or an |
| 137 | // exponential representation. |
| 138 | // Example with decimal_in_shortest_low = -6, |
| 139 | // decimal_in_shortest_high = 21, |
| 140 | // EMIT_POSITIVE_EXPONENT_SIGN activated, and |
| 141 | // EMIT_TRAILING_DECIMAL_POINT deactived: |
| 142 | // ToShortest(0.000001) -> "0.000001" |
| 143 | // ToShortest(0.0000001) -> "1e-7" |
| 144 | // ToShortest(111111111111111111111.0) -> "111111111111111110000" |
| 145 | // ToShortest(100000000000000000000.0) -> "100000000000000000000" |
| 146 | // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21" |
| 147 | // |
| 148 | // Note: the conversion may round the output if the returned string |
| 149 | // is accurate enough to uniquely identify the input-number. |
| 150 | // For example the most precise representation of the double 9e59 equals |
| 151 | // "899999999999999918767229449717619953810131273674690656206848", but |
| 152 | // the converter will return the shorter (but still correct) "9e59". |
| 153 | // |
| 154 | // Returns true if the conversion succeeds. The conversion always succeeds |
| 155 | // except when the input value is special and no infinity_symbol or |
| 156 | // nan_symbol has been given to the constructor. |
| 157 | bool ToShortest(double value, StringBuilder* result_builder) const { |
| 158 | return ToShortestIeeeNumber(value, result_builder, SHORTEST); |
| 159 | } |
| 160 | |
| 161 | // Same as ToShortest, but for single-precision floats. |
| 162 | bool ToShortestSingle(float value, StringBuilder* result_builder) const { |
| 163 | return ToShortestIeeeNumber(value, result_builder, SHORTEST_SINGLE); |
| 164 | } |
| 165 | |
| 166 | |
| 167 | // Computes a decimal representation with a fixed number of digits after the |
| 168 | // decimal point. The last emitted digit is rounded. |
| 169 | // |
| 170 | // Examples: |
| 171 | // ToFixed(3.12, 1) -> "3.1" |
| 172 | // ToFixed(3.1415, 3) -> "3.142" |
| 173 | // ToFixed(1234.56789, 4) -> "1234.5679" |
| 174 | // ToFixed(1.23, 5) -> "1.23000" |
| 175 | // ToFixed(0.1, 4) -> "0.1000" |
| 176 | // ToFixed(1e30, 2) -> "1000000000000000019884624838656.00" |
| 177 | // ToFixed(0.1, 30) -> "0.100000000000000005551115123126" |
| 178 | // ToFixed(0.1, 17) -> "0.10000000000000001" |
| 179 | // |
| 180 | // If requested_digits equals 0, then the tail of the result depends on |
| 181 | // the EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT. |
| 182 | // Examples, for requested_digits == 0, |
| 183 | // let EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT be |
| 184 | // - false and false: then 123.45 -> 123 |
| 185 | // 0.678 -> 1 |
| 186 | // - true and false: then 123.45 -> 123. |
| 187 | // 0.678 -> 1. |
| 188 | // - true and true: then 123.45 -> 123.0 |
| 189 | // 0.678 -> 1.0 |
| 190 | // |
| 191 | // Returns true if the conversion succeeds. The conversion always succeeds |
| 192 | // except for the following cases: |
| 193 | // - the input value is special and no infinity_symbol or nan_symbol has |
| 194 | // been provided to the constructor, |
| 195 | // - 'value' > 10^kMaxFixedDigitsBeforePoint, or |
| 196 | // - 'requested_digits' > kMaxFixedDigitsAfterPoint. |
| 197 | // The last two conditions imply that the result will never contain more than |
| 198 | // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters |
| 199 | // (one additional character for the sign, and one for the decimal point). |
| 200 | bool ToFixed(double value, |
| 201 | int requested_digits, |
| 202 | StringBuilder* result_builder) const; |
| 203 | |
| 204 | // Computes a representation in exponential format with requested_digits |
| 205 | // after the decimal point. The last emitted digit is rounded. |
| 206 | // If requested_digits equals -1, then the shortest exponential representation |
| 207 | // is computed. |
| 208 | // |
| 209 | // Examples with EMIT_POSITIVE_EXPONENT_SIGN deactivated, and |
| 210 | // exponent_character set to 'e'. |
| 211 | // ToExponential(3.12, 1) -> "3.1e0" |
| 212 | // ToExponential(5.0, 3) -> "5.000e0" |
| 213 | // ToExponential(0.001, 2) -> "1.00e-3" |
| 214 | // ToExponential(3.1415, -1) -> "3.1415e0" |
| 215 | // ToExponential(3.1415, 4) -> "3.1415e0" |
| 216 | // ToExponential(3.1415, 3) -> "3.142e0" |
| 217 | // ToExponential(123456789000000, 3) -> "1.235e14" |
| 218 | // ToExponential(1000000000000000019884624838656.0, -1) -> "1e30" |
| 219 | // ToExponential(1000000000000000019884624838656.0, 32) -> |
| 220 | // "1.00000000000000001988462483865600e30" |
| 221 | // ToExponential(1234, 0) -> "1e3" |
| 222 | // |
| 223 | // Returns true if the conversion succeeds. The conversion always succeeds |
| 224 | // except for the following cases: |
| 225 | // - the input value is special and no infinity_symbol or nan_symbol has |
| 226 | // been provided to the constructor, |
| 227 | // - 'requested_digits' > kMaxExponentialDigits. |
| 228 | // The last condition implies that the result will never contain more than |
| 229 | // kMaxExponentialDigits + 8 characters (the sign, the digit before the |
| 230 | // decimal point, the decimal point, the exponent character, the |
| 231 | // exponent's sign, and at most 3 exponent digits). |
| 232 | bool ToExponential(double value, |
| 233 | int requested_digits, |
| 234 | StringBuilder* result_builder) const; |
| 235 | |
| 236 | // Computes 'precision' leading digits of the given 'value' and returns them |
| 237 | // either in exponential or decimal format, depending on |
| 238 | // max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the |
| 239 | // constructor). |
| 240 | // The last computed digit is rounded. |
| 241 | // |
| 242 | // Example with max_leading_padding_zeroes_in_precision_mode = 6. |
| 243 | // ToPrecision(0.0000012345, 2) -> "0.0000012" |
| 244 | // ToPrecision(0.00000012345, 2) -> "1.2e-7" |
| 245 | // Similarily the converter may add up to |
| 246 | // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid |
| 247 | // returning an exponential representation. A zero added by the |
| 248 | // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit. |
| 249 | // Examples for max_trailing_padding_zeroes_in_precision_mode = 1: |
| 250 | // ToPrecision(230.0, 2) -> "230" |
| 251 | // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT. |
| 252 | // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT. |
| 253 | // Examples for max_trailing_padding_zeroes_in_precision_mode = 3, and no |
| 254 | // EMIT_TRAILING_ZERO_AFTER_POINT: |
| 255 | // ToPrecision(123450.0, 6) -> "123450" |
| 256 | // ToPrecision(123450.0, 5) -> "123450" |
| 257 | // ToPrecision(123450.0, 4) -> "123500" |
| 258 | // ToPrecision(123450.0, 3) -> "123000" |
| 259 | // ToPrecision(123450.0, 2) -> "1.2e5" |
| 260 | // |
| 261 | // Returns true if the conversion succeeds. The conversion always succeeds |
| 262 | // except for the following cases: |
| 263 | // - the input value is special and no infinity_symbol or nan_symbol has |
| 264 | // been provided to the constructor, |
| 265 | // - precision < kMinPericisionDigits |
| 266 | // - precision > kMaxPrecisionDigits |
| 267 | // The last condition implies that the result will never contain more than |
| 268 | // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the |
| 269 | // exponent character, the exponent's sign, and at most 3 exponent digits). |
| 270 | bool ToPrecision(double value, |
| 271 | int precision, |
| 272 | StringBuilder* result_builder) const; |
| 273 | |
| 274 | enum DtoaMode { |
| 275 | // Produce the shortest correct representation. |
| 276 | // For example the output of 0.299999999999999988897 is (the less accurate |
| 277 | // but correct) 0.3. |
| 278 | SHORTEST, |
| 279 | // Same as SHORTEST, but for single-precision floats. |
| 280 | SHORTEST_SINGLE, |
| 281 | // Produce a fixed number of digits after the decimal point. |
| 282 | // For instance fixed(0.1, 4) becomes 0.1000 |
| 283 | // If the input number is big, the output will be big. |
| 284 | FIXED, |
| 285 | // Fixed number of digits (independent of the decimal point). |
| 286 | PRECISION |
| 287 | }; |
| 288 | |
| 289 | // The maximal number of digits that are needed to emit a double in base 10. |
| 290 | // A higher precision can be achieved by using more digits, but the shortest |
| 291 | // accurate representation of any double will never use more digits than |
| 292 | // kBase10MaximalLength. |
| 293 | // Note that DoubleToAscii null-terminates its input. So the given buffer |
| 294 | // should be at least kBase10MaximalLength + 1 characters long. |
| 295 | static const int kBase10MaximalLength = 17; |
| 296 | |
| 297 | // Converts the given double 'v' to ascii. 'v' must not be NaN, +Infinity, or |
| 298 | // -Infinity. In SHORTEST_SINGLE-mode this restriction also applies to 'v' |
| 299 | // after it has been casted to a single-precision float. That is, in this |
| 300 | // mode static_cast<float>(v) must not be NaN, +Infinity or -Infinity. |
| 301 | // |
| 302 | // The result should be interpreted as buffer * 10^(point-length). |
| 303 | // |
| 304 | // The output depends on the given mode: |
| 305 | // - SHORTEST: produce the least amount of digits for which the internal |
| 306 | // identity requirement is still satisfied. If the digits are printed |
| 307 | // (together with the correct exponent) then reading this number will give |
| 308 | // 'v' again. The buffer will choose the representation that is closest to |
| 309 | // 'v'. If there are two at the same distance, than the one farther away |
| 310 | // from 0 is chosen (halfway cases - ending with 5 - are rounded up). |
| 311 | // In this mode the 'requested_digits' parameter is ignored. |
| 312 | // - SHORTEST_SINGLE: same as SHORTEST but with single-precision. |
| 313 | // - FIXED: produces digits necessary to print a given number with |
| 314 | // 'requested_digits' digits after the decimal point. The produced digits |
| 315 | // might be too short in which case the caller has to fill the remainder |
| 316 | // with '0's. |
| 317 | // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. |
| 318 | // Halfway cases are rounded towards +/-Infinity (away from 0). The call |
| 319 | // toFixed(0.15, 2) thus returns buffer="2", point=0. |
| 320 | // The returned buffer may contain digits that would be truncated from the |
| 321 | // shortest representation of the input. |
| 322 | // - PRECISION: produces 'requested_digits' where the first digit is not '0'. |
| 323 | // Even though the length of produced digits usually equals |
| 324 | // 'requested_digits', the function is allowed to return fewer digits, in |
| 325 | // which case the caller has to fill the missing digits with '0's. |
| 326 | // Halfway cases are again rounded away from 0. |
| 327 | // DoubleToAscii expects the given buffer to be big enough to hold all |
| 328 | // digits and a terminating null-character. In SHORTEST-mode it expects a |
| 329 | // buffer of at least kBase10MaximalLength + 1. In all other modes the |
| 330 | // requested_digits parameter and the padding-zeroes limit the size of the |
| 331 | // output. Don't forget the decimal point, the exponent character and the |
| 332 | // terminating null-character when computing the maximal output size. |
| 333 | // The given length is only used in debug mode to ensure the buffer is big |
| 334 | // enough. |
| 335 | static void DoubleToAscii(double v, |
| 336 | DtoaMode mode, |
| 337 | int requested_digits, |
| 338 | char* buffer, |
| 339 | int buffer_length, |
| 340 | bool* sign, |
| 341 | int* length, |
| 342 | int* point); |
| 343 | |
| 344 | private: |
| 345 | // Implementation for ToShortest and ToShortestSingle. |
| 346 | bool ToShortestIeeeNumber(double value, |
| 347 | StringBuilder* result_builder, |
| 348 | DtoaMode mode) const; |
| 349 | |
| 350 | // If the value is a special value (NaN or Infinity) constructs the |
| 351 | // corresponding string using the configured infinity/nan-symbol. |
| 352 | // If either of them is NULL or the value is not special then the |
| 353 | // function returns false. |
| 354 | bool HandleSpecialValues(double value, StringBuilder* result_builder) const; |
| 355 | // Constructs an exponential representation (i.e. 1.234e56). |
| 356 | // The given exponent assumes a decimal point after the first decimal digit. |
| 357 | void CreateExponentialRepresentation(const char* decimal_digits, |
| 358 | int length, |
| 359 | int exponent, |
| 360 | StringBuilder* result_builder) const; |
| 361 | // Creates a decimal representation (i.e 1234.5678). |
| 362 | void CreateDecimalRepresentation(const char* decimal_digits, |
| 363 | int length, |
| 364 | int decimal_point, |
| 365 | int digits_after_point, |
| 366 | StringBuilder* result_builder) const; |
| 367 | |
| 368 | const int flags_; |
| 369 | const char* const infinity_symbol_; |
| 370 | const char* const nan_symbol_; |
| 371 | const char exponent_character_; |
| 372 | const int decimal_in_shortest_low_; |
| 373 | const int decimal_in_shortest_high_; |
| 374 | const int max_leading_padding_zeroes_in_precision_mode_; |
| 375 | const int max_trailing_padding_zeroes_in_precision_mode_; |
| 376 | |
| 377 | DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter); |
| 378 | }; |
| 379 | |
| 380 | |
| 381 | class StringToDoubleConverter { |
| 382 | public: |
| 383 | // Enumeration for allowing octals and ignoring junk when converting |
| 384 | // strings to numbers. |
| 385 | enum Flags { |
| 386 | NO_FLAGS = 0, |
| 387 | ALLOW_HEX = 1, |
| 388 | ALLOW_OCTALS = 2, |
| 389 | ALLOW_TRAILING_JUNK = 4, |
| 390 | ALLOW_LEADING_SPACES = 8, |
| 391 | ALLOW_TRAILING_SPACES = 16, |
| 392 | ALLOW_SPACES_AFTER_SIGN = 32 |
| 393 | }; |
| 394 | |
| 395 | // Flags should be a bit-or combination of the possible Flags-enum. |
| 396 | // - NO_FLAGS: no special flags. |
| 397 | // - ALLOW_HEX: recognizes the prefix "0x". Hex numbers may only be integers. |
| 398 | // Ex: StringToDouble("0x1234") -> 4660.0 |
| 399 | // In StringToDouble("0x1234.56") the characters ".56" are trailing |
| 400 | // junk. The result of the call is hence dependent on |
| 401 | // the ALLOW_TRAILING_JUNK flag and/or the junk value. |
| 402 | // With this flag "0x" is a junk-string. Even with ALLOW_TRAILING_JUNK, |
| 403 | // the string will not be parsed as "0" followed by junk. |
| 404 | // |
| 405 | // - ALLOW_OCTALS: recognizes the prefix "0" for octals: |
| 406 | // If a sequence of octal digits starts with '0', then the number is |
| 407 | // read as octal integer. Octal numbers may only be integers. |
| 408 | // Ex: StringToDouble("01234") -> 668.0 |
| 409 | // StringToDouble("012349") -> 12349.0 // Not a sequence of octal |
| 410 | // // digits. |
| 411 | // In StringToDouble("01234.56") the characters ".56" are trailing |
| 412 | // junk. The result of the call is hence dependent on |
| 413 | // the ALLOW_TRAILING_JUNK flag and/or the junk value. |
| 414 | // In StringToDouble("01234e56") the characters "e56" are trailing |
| 415 | // junk, too. |
| 416 | // - ALLOW_TRAILING_JUNK: ignore trailing characters that are not part of |
| 417 | // a double literal. |
| 418 | // - ALLOW_LEADING_SPACES: skip over leading whitespace, including spaces, |
| 419 | // new-lines, and tabs. |
| 420 | // - ALLOW_TRAILING_SPACES: ignore trailing whitespace. |
| 421 | // - ALLOW_SPACES_AFTER_SIGN: ignore whitespace after the sign. |
| 422 | // Ex: StringToDouble("- 123.2") -> -123.2. |
| 423 | // StringToDouble("+ 123.2") -> 123.2 |
| 424 | // |
| 425 | // empty_string_value is returned when an empty string is given as input. |
| 426 | // If ALLOW_LEADING_SPACES or ALLOW_TRAILING_SPACES are set, then a string |
| 427 | // containing only spaces is converted to the 'empty_string_value', too. |
| 428 | // |
| 429 | // junk_string_value is returned when |
| 430 | // a) ALLOW_TRAILING_JUNK is not set, and a junk character (a character not |
| 431 | // part of a double-literal) is found. |
| 432 | // b) ALLOW_TRAILING_JUNK is set, but the string does not start with a |
| 433 | // double literal. |
| 434 | // |
| 435 | // infinity_symbol and nan_symbol are strings that are used to detect |
| 436 | // inputs that represent infinity and NaN. They can be null, in which case |
| 437 | // they are ignored. |
| 438 | // The conversion routine first reads any possible signs. Then it compares the |
| 439 | // following character of the input-string with the first character of |
| 440 | // the infinity, and nan-symbol. If either matches, the function assumes, that |
| 441 | // a match has been found, and expects the following input characters to match |
| 442 | // the remaining characters of the special-value symbol. |
| 443 | // This means that the following restrictions apply to special-value symbols: |
| 444 | // - they must not start with signs ('+', or '-'), |
| 445 | // - they must not have the same first character. |
| 446 | // - they must not start with digits. |
| 447 | // |
| 448 | // Examples: |
| 449 | // flags = ALLOW_HEX | ALLOW_TRAILING_JUNK, |
| 450 | // empty_string_value = 0.0, |
| 451 | // junk_string_value = NaN, |
| 452 | // infinity_symbol = "infinity", |
| 453 | // nan_symbol = "nan": |
| 454 | // StringToDouble("0x1234") -> 4660.0. |
| 455 | // StringToDouble("0x1234K") -> 4660.0. |
| 456 | // StringToDouble("") -> 0.0 // empty_string_value. |
| 457 | // StringToDouble(" ") -> NaN // junk_string_value. |
| 458 | // StringToDouble(" 1") -> NaN // junk_string_value. |
| 459 | // StringToDouble("0x") -> NaN // junk_string_value. |
| 460 | // StringToDouble("-123.45") -> -123.45. |
| 461 | // StringToDouble("--123.45") -> NaN // junk_string_value. |
| 462 | // StringToDouble("123e45") -> 123e45. |
| 463 | // StringToDouble("123E45") -> 123e45. |
| 464 | // StringToDouble("123e+45") -> 123e45. |
| 465 | // StringToDouble("123E-45") -> 123e-45. |
| 466 | // StringToDouble("123e") -> 123.0 // trailing junk ignored. |
| 467 | // StringToDouble("123e-") -> 123.0 // trailing junk ignored. |
| 468 | // StringToDouble("+NaN") -> NaN // NaN string literal. |
| 469 | // StringToDouble("-infinity") -> -inf. // infinity literal. |
| 470 | // StringToDouble("Infinity") -> NaN // junk_string_value. |
| 471 | // |
| 472 | // flags = ALLOW_OCTAL | ALLOW_LEADING_SPACES, |
| 473 | // empty_string_value = 0.0, |
| 474 | // junk_string_value = NaN, |
| 475 | // infinity_symbol = NULL, |
| 476 | // nan_symbol = NULL: |
| 477 | // StringToDouble("0x1234") -> NaN // junk_string_value. |
| 478 | // StringToDouble("01234") -> 668.0. |
| 479 | // StringToDouble("") -> 0.0 // empty_string_value. |
| 480 | // StringToDouble(" ") -> 0.0 // empty_string_value. |
| 481 | // StringToDouble(" 1") -> 1.0 |
| 482 | // StringToDouble("0x") -> NaN // junk_string_value. |
| 483 | // StringToDouble("0123e45") -> NaN // junk_string_value. |
| 484 | // StringToDouble("01239E45") -> 1239e45. |
| 485 | // StringToDouble("-infinity") -> NaN // junk_string_value. |
| 486 | // StringToDouble("NaN") -> NaN // junk_string_value. |
| 487 | StringToDoubleConverter(int flags, |
| 488 | double empty_string_value, |
| 489 | double junk_string_value, |
| 490 | const char* infinity_symbol, |
| 491 | const char* nan_symbol) |
| 492 | : flags_(flags), |
| 493 | empty_string_value_(empty_string_value), |
| 494 | junk_string_value_(junk_string_value), |
| 495 | infinity_symbol_(infinity_symbol), |
| 496 | nan_symbol_(nan_symbol) { |
| 497 | } |
| 498 | |
| 499 | // Performs the conversion. |
| 500 | // The output parameter 'processed_characters_count' is set to the number |
| 501 | // of characters that have been processed to read the number. |
| 502 | // Spaces than are processed with ALLOW_{LEADING|TRAILING}_SPACES are included |
| 503 | // in the 'processed_characters_count'. Trailing junk is never included. |
| 504 | double StringToDouble(const char* buffer, |
| 505 | int length, |
| 506 | int* processed_characters_count) const; |
| 507 | |
| 508 | // Same as StringToDouble above but for 16 bit characters. |
| 509 | double StringToDouble(const uc16* buffer, |
| 510 | int length, |
| 511 | int* processed_characters_count) const; |
| 512 | |
| 513 | // Same as StringToDouble but reads a float. |
| 514 | // Note that this is not equivalent to static_cast<float>(StringToDouble(...)) |
| 515 | // due to potential double-rounding. |
| 516 | float StringToFloat(const char* buffer, |
| 517 | int length, |
| 518 | int* processed_characters_count) const; |
| 519 | |
| 520 | // Same as StringToFloat above but for 16 bit characters. |
| 521 | float StringToFloat(const uc16* buffer, |
| 522 | int length, |
| 523 | int* processed_characters_count) const; |
| 524 | |
| 525 | private: |
| 526 | const int flags_; |
| 527 | const double empty_string_value_; |
| 528 | const double junk_string_value_; |
| 529 | const char* const infinity_symbol_; |
| 530 | const char* const nan_symbol_; |
| 531 | |
| 532 | template <class Iterator> |
| 533 | double StringToIeee(Iterator start_pointer, |
| 534 | int length, |
| 535 | bool read_as_double, |
| 536 | int* processed_characters_count) const; |
| 537 | |
| 538 | DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter); |
| 539 | }; |
| 540 | |
| 541 | } // namespace double_conversion |
| 542 | |
| 543 | #endif // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ |
| 544 | |