1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mfbt/double-conversion/double-conversion.cc Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,892 @@
1.4 +// Copyright 2010 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
1.22 +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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
1.27 +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
1.28 +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
1.29 +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.30 +
1.31 +#include <limits.h>
1.32 +#include <math.h>
1.33 +
1.34 +#include "double-conversion.h"
1.35 +
1.36 +#include "bignum-dtoa.h"
1.37 +#include "fast-dtoa.h"
1.38 +#include "fixed-dtoa.h"
1.39 +#include "ieee.h"
1.40 +#include "strtod.h"
1.41 +#include "utils.h"
1.42 +
1.43 +namespace double_conversion {
1.44 +
1.45 +const DoubleToStringConverter& DoubleToStringConverter::EcmaScriptConverter() {
1.46 + int flags = UNIQUE_ZERO | EMIT_POSITIVE_EXPONENT_SIGN;
1.47 + static DoubleToStringConverter converter(flags,
1.48 + "Infinity",
1.49 + "NaN",
1.50 + 'e',
1.51 + -6, 21,
1.52 + 6, 0);
1.53 + return converter;
1.54 +}
1.55 +
1.56 +
1.57 +bool DoubleToStringConverter::HandleSpecialValues(
1.58 + double value,
1.59 + StringBuilder* result_builder) const {
1.60 + Double double_inspect(value);
1.61 + if (double_inspect.IsInfinite()) {
1.62 + if (infinity_symbol_ == NULL) return false;
1.63 + if (value < 0) {
1.64 + result_builder->AddCharacter('-');
1.65 + }
1.66 + result_builder->AddString(infinity_symbol_);
1.67 + return true;
1.68 + }
1.69 + if (double_inspect.IsNan()) {
1.70 + if (nan_symbol_ == NULL) return false;
1.71 + result_builder->AddString(nan_symbol_);
1.72 + return true;
1.73 + }
1.74 + return false;
1.75 +}
1.76 +
1.77 +
1.78 +void DoubleToStringConverter::CreateExponentialRepresentation(
1.79 + const char* decimal_digits,
1.80 + int length,
1.81 + int exponent,
1.82 + StringBuilder* result_builder) const {
1.83 + ASSERT(length != 0);
1.84 + result_builder->AddCharacter(decimal_digits[0]);
1.85 + if (length != 1) {
1.86 + result_builder->AddCharacter('.');
1.87 + result_builder->AddSubstring(&decimal_digits[1], length-1);
1.88 + }
1.89 + result_builder->AddCharacter(exponent_character_);
1.90 + if (exponent < 0) {
1.91 + result_builder->AddCharacter('-');
1.92 + exponent = -exponent;
1.93 + } else {
1.94 + if ((flags_ & EMIT_POSITIVE_EXPONENT_SIGN) != 0) {
1.95 + result_builder->AddCharacter('+');
1.96 + }
1.97 + }
1.98 + if (exponent == 0) {
1.99 + result_builder->AddCharacter('0');
1.100 + return;
1.101 + }
1.102 + ASSERT(exponent < 1e4);
1.103 + const int kMaxExponentLength = 5;
1.104 + char buffer[kMaxExponentLength + 1];
1.105 + buffer[kMaxExponentLength] = '\0';
1.106 + int first_char_pos = kMaxExponentLength;
1.107 + while (exponent > 0) {
1.108 + buffer[--first_char_pos] = '0' + (exponent % 10);
1.109 + exponent /= 10;
1.110 + }
1.111 + result_builder->AddSubstring(&buffer[first_char_pos],
1.112 + kMaxExponentLength - first_char_pos);
1.113 +}
1.114 +
1.115 +
1.116 +void DoubleToStringConverter::CreateDecimalRepresentation(
1.117 + const char* decimal_digits,
1.118 + int length,
1.119 + int decimal_point,
1.120 + int digits_after_point,
1.121 + StringBuilder* result_builder) const {
1.122 + // Create a representation that is padded with zeros if needed.
1.123 + if (decimal_point <= 0) {
1.124 + // "0.00000decimal_rep".
1.125 + result_builder->AddCharacter('0');
1.126 + if (digits_after_point > 0) {
1.127 + result_builder->AddCharacter('.');
1.128 + result_builder->AddPadding('0', -decimal_point);
1.129 + ASSERT(length <= digits_after_point - (-decimal_point));
1.130 + result_builder->AddSubstring(decimal_digits, length);
1.131 + int remaining_digits = digits_after_point - (-decimal_point) - length;
1.132 + result_builder->AddPadding('0', remaining_digits);
1.133 + }
1.134 + } else if (decimal_point >= length) {
1.135 + // "decimal_rep0000.00000" or "decimal_rep.0000"
1.136 + result_builder->AddSubstring(decimal_digits, length);
1.137 + result_builder->AddPadding('0', decimal_point - length);
1.138 + if (digits_after_point > 0) {
1.139 + result_builder->AddCharacter('.');
1.140 + result_builder->AddPadding('0', digits_after_point);
1.141 + }
1.142 + } else {
1.143 + // "decima.l_rep000"
1.144 + ASSERT(digits_after_point > 0);
1.145 + result_builder->AddSubstring(decimal_digits, decimal_point);
1.146 + result_builder->AddCharacter('.');
1.147 + ASSERT(length - decimal_point <= digits_after_point);
1.148 + result_builder->AddSubstring(&decimal_digits[decimal_point],
1.149 + length - decimal_point);
1.150 + int remaining_digits = digits_after_point - (length - decimal_point);
1.151 + result_builder->AddPadding('0', remaining_digits);
1.152 + }
1.153 + if (digits_after_point == 0) {
1.154 + if ((flags_ & EMIT_TRAILING_DECIMAL_POINT) != 0) {
1.155 + result_builder->AddCharacter('.');
1.156 + }
1.157 + if ((flags_ & EMIT_TRAILING_ZERO_AFTER_POINT) != 0) {
1.158 + result_builder->AddCharacter('0');
1.159 + }
1.160 + }
1.161 +}
1.162 +
1.163 +
1.164 +bool DoubleToStringConverter::ToShortestIeeeNumber(
1.165 + double value,
1.166 + StringBuilder* result_builder,
1.167 + DoubleToStringConverter::DtoaMode mode) const {
1.168 + ASSERT(mode == SHORTEST || mode == SHORTEST_SINGLE);
1.169 + if (Double(value).IsSpecial()) {
1.170 + return HandleSpecialValues(value, result_builder);
1.171 + }
1.172 +
1.173 + int decimal_point;
1.174 + bool sign;
1.175 + const int kDecimalRepCapacity = kBase10MaximalLength + 1;
1.176 + char decimal_rep[kDecimalRepCapacity];
1.177 + int decimal_rep_length;
1.178 +
1.179 + DoubleToAscii(value, mode, 0, decimal_rep, kDecimalRepCapacity,
1.180 + &sign, &decimal_rep_length, &decimal_point);
1.181 +
1.182 + bool unique_zero = (flags_ & UNIQUE_ZERO) != 0;
1.183 + if (sign && (value != 0.0 || !unique_zero)) {
1.184 + result_builder->AddCharacter('-');
1.185 + }
1.186 +
1.187 + int exponent = decimal_point - 1;
1.188 + if ((decimal_in_shortest_low_ <= exponent) &&
1.189 + (exponent < decimal_in_shortest_high_)) {
1.190 + CreateDecimalRepresentation(decimal_rep, decimal_rep_length,
1.191 + decimal_point,
1.192 + Max(0, decimal_rep_length - decimal_point),
1.193 + result_builder);
1.194 + } else {
1.195 + CreateExponentialRepresentation(decimal_rep, decimal_rep_length, exponent,
1.196 + result_builder);
1.197 + }
1.198 + return true;
1.199 +}
1.200 +
1.201 +
1.202 +bool DoubleToStringConverter::ToFixed(double value,
1.203 + int requested_digits,
1.204 + StringBuilder* result_builder) const {
1.205 + ASSERT(kMaxFixedDigitsBeforePoint == 60);
1.206 + const double kFirstNonFixed = 1e60;
1.207 +
1.208 + if (Double(value).IsSpecial()) {
1.209 + return HandleSpecialValues(value, result_builder);
1.210 + }
1.211 +
1.212 + if (requested_digits > kMaxFixedDigitsAfterPoint) return false;
1.213 + if (value >= kFirstNonFixed || value <= -kFirstNonFixed) return false;
1.214 +
1.215 + // Find a sufficiently precise decimal representation of n.
1.216 + int decimal_point;
1.217 + bool sign;
1.218 + // Add space for the '\0' byte.
1.219 + const int kDecimalRepCapacity =
1.220 + kMaxFixedDigitsBeforePoint + kMaxFixedDigitsAfterPoint + 1;
1.221 + char decimal_rep[kDecimalRepCapacity];
1.222 + int decimal_rep_length;
1.223 + DoubleToAscii(value, FIXED, requested_digits,
1.224 + decimal_rep, kDecimalRepCapacity,
1.225 + &sign, &decimal_rep_length, &decimal_point);
1.226 +
1.227 + bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);
1.228 + if (sign && (value != 0.0 || !unique_zero)) {
1.229 + result_builder->AddCharacter('-');
1.230 + }
1.231 +
1.232 + CreateDecimalRepresentation(decimal_rep, decimal_rep_length, decimal_point,
1.233 + requested_digits, result_builder);
1.234 + return true;
1.235 +}
1.236 +
1.237 +
1.238 +bool DoubleToStringConverter::ToExponential(
1.239 + double value,
1.240 + int requested_digits,
1.241 + StringBuilder* result_builder) const {
1.242 + if (Double(value).IsSpecial()) {
1.243 + return HandleSpecialValues(value, result_builder);
1.244 + }
1.245 +
1.246 + if (requested_digits < -1) return false;
1.247 + if (requested_digits > kMaxExponentialDigits) return false;
1.248 +
1.249 + int decimal_point;
1.250 + bool sign;
1.251 + // Add space for digit before the decimal point and the '\0' character.
1.252 + const int kDecimalRepCapacity = kMaxExponentialDigits + 2;
1.253 + ASSERT(kDecimalRepCapacity > kBase10MaximalLength);
1.254 + char decimal_rep[kDecimalRepCapacity];
1.255 + int decimal_rep_length;
1.256 +
1.257 + if (requested_digits == -1) {
1.258 + DoubleToAscii(value, SHORTEST, 0,
1.259 + decimal_rep, kDecimalRepCapacity,
1.260 + &sign, &decimal_rep_length, &decimal_point);
1.261 + } else {
1.262 + DoubleToAscii(value, PRECISION, requested_digits + 1,
1.263 + decimal_rep, kDecimalRepCapacity,
1.264 + &sign, &decimal_rep_length, &decimal_point);
1.265 + ASSERT(decimal_rep_length <= requested_digits + 1);
1.266 +
1.267 + for (int i = decimal_rep_length; i < requested_digits + 1; ++i) {
1.268 + decimal_rep[i] = '0';
1.269 + }
1.270 + decimal_rep_length = requested_digits + 1;
1.271 + }
1.272 +
1.273 + bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);
1.274 + if (sign && (value != 0.0 || !unique_zero)) {
1.275 + result_builder->AddCharacter('-');
1.276 + }
1.277 +
1.278 + int exponent = decimal_point - 1;
1.279 + CreateExponentialRepresentation(decimal_rep,
1.280 + decimal_rep_length,
1.281 + exponent,
1.282 + result_builder);
1.283 + return true;
1.284 +}
1.285 +
1.286 +
1.287 +bool DoubleToStringConverter::ToPrecision(double value,
1.288 + int precision,
1.289 + bool* used_exponential_notation,
1.290 + StringBuilder* result_builder) const {
1.291 + *used_exponential_notation = false;
1.292 + if (Double(value).IsSpecial()) {
1.293 + return HandleSpecialValues(value, result_builder);
1.294 + }
1.295 +
1.296 + if (precision < kMinPrecisionDigits || precision > kMaxPrecisionDigits) {
1.297 + return false;
1.298 + }
1.299 +
1.300 + // Find a sufficiently precise decimal representation of n.
1.301 + int decimal_point;
1.302 + bool sign;
1.303 + // Add one for the terminating null character.
1.304 + const int kDecimalRepCapacity = kMaxPrecisionDigits + 1;
1.305 + char decimal_rep[kDecimalRepCapacity];
1.306 + int decimal_rep_length;
1.307 +
1.308 + DoubleToAscii(value, PRECISION, precision,
1.309 + decimal_rep, kDecimalRepCapacity,
1.310 + &sign, &decimal_rep_length, &decimal_point);
1.311 + ASSERT(decimal_rep_length <= precision);
1.312 +
1.313 + bool unique_zero = ((flags_ & UNIQUE_ZERO) != 0);
1.314 + if (sign && (value != 0.0 || !unique_zero)) {
1.315 + result_builder->AddCharacter('-');
1.316 + }
1.317 +
1.318 + // The exponent if we print the number as x.xxeyyy. That is with the
1.319 + // decimal point after the first digit.
1.320 + int exponent = decimal_point - 1;
1.321 +
1.322 + int extra_zero = ((flags_ & EMIT_TRAILING_ZERO_AFTER_POINT) != 0) ? 1 : 0;
1.323 + if ((-decimal_point + 1 > max_leading_padding_zeroes_in_precision_mode_) ||
1.324 + (decimal_point - precision + extra_zero >
1.325 + max_trailing_padding_zeroes_in_precision_mode_)) {
1.326 + // Fill buffer to contain 'precision' digits.
1.327 + // Usually the buffer is already at the correct length, but 'DoubleToAscii'
1.328 + // is allowed to return less characters.
1.329 + for (int i = decimal_rep_length; i < precision; ++i) {
1.330 + decimal_rep[i] = '0';
1.331 + }
1.332 +
1.333 + *used_exponential_notation = true;
1.334 + CreateExponentialRepresentation(decimal_rep,
1.335 + precision,
1.336 + exponent,
1.337 + result_builder);
1.338 + } else {
1.339 + CreateDecimalRepresentation(decimal_rep, decimal_rep_length, decimal_point,
1.340 + Max(0, precision - decimal_point),
1.341 + result_builder);
1.342 + }
1.343 + return true;
1.344 +}
1.345 +
1.346 +
1.347 +static BignumDtoaMode DtoaToBignumDtoaMode(
1.348 + DoubleToStringConverter::DtoaMode dtoa_mode) {
1.349 + switch (dtoa_mode) {
1.350 + case DoubleToStringConverter::SHORTEST: return BIGNUM_DTOA_SHORTEST;
1.351 + case DoubleToStringConverter::SHORTEST_SINGLE:
1.352 + return BIGNUM_DTOA_SHORTEST_SINGLE;
1.353 + case DoubleToStringConverter::FIXED: return BIGNUM_DTOA_FIXED;
1.354 + case DoubleToStringConverter::PRECISION: return BIGNUM_DTOA_PRECISION;
1.355 + default:
1.356 + UNREACHABLE();
1.357 + return BIGNUM_DTOA_SHORTEST; // To silence compiler.
1.358 + }
1.359 +}
1.360 +
1.361 +
1.362 +void DoubleToStringConverter::DoubleToAscii(double v,
1.363 + DtoaMode mode,
1.364 + int requested_digits,
1.365 + char* buffer,
1.366 + int buffer_length,
1.367 + bool* sign,
1.368 + int* length,
1.369 + int* point) {
1.370 + Vector<char> vector(buffer, buffer_length);
1.371 + ASSERT(!Double(v).IsSpecial());
1.372 + ASSERT(mode == SHORTEST || mode == SHORTEST_SINGLE || requested_digits >= 0);
1.373 +
1.374 + if (Double(v).Sign() < 0) {
1.375 + *sign = true;
1.376 + v = -v;
1.377 + } else {
1.378 + *sign = false;
1.379 + }
1.380 +
1.381 + if (mode == PRECISION && requested_digits == 0) {
1.382 + vector[0] = '\0';
1.383 + *length = 0;
1.384 + return;
1.385 + }
1.386 +
1.387 + if (v == 0) {
1.388 + vector[0] = '0';
1.389 + vector[1] = '\0';
1.390 + *length = 1;
1.391 + *point = 1;
1.392 + return;
1.393 + }
1.394 +
1.395 + bool fast_worked;
1.396 + switch (mode) {
1.397 + case SHORTEST:
1.398 + fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST, 0, vector, length, point);
1.399 + break;
1.400 + case SHORTEST_SINGLE:
1.401 + fast_worked = FastDtoa(v, FAST_DTOA_SHORTEST_SINGLE, 0,
1.402 + vector, length, point);
1.403 + break;
1.404 + case FIXED:
1.405 + fast_worked = FastFixedDtoa(v, requested_digits, vector, length, point);
1.406 + break;
1.407 + case PRECISION:
1.408 + fast_worked = FastDtoa(v, FAST_DTOA_PRECISION, requested_digits,
1.409 + vector, length, point);
1.410 + break;
1.411 + default:
1.412 + UNREACHABLE();
1.413 + fast_worked = false;
1.414 + }
1.415 + if (fast_worked) return;
1.416 +
1.417 + // If the fast dtoa didn't succeed use the slower bignum version.
1.418 + BignumDtoaMode bignum_mode = DtoaToBignumDtoaMode(mode);
1.419 + BignumDtoa(v, bignum_mode, requested_digits, vector, length, point);
1.420 + vector[*length] = '\0';
1.421 +}
1.422 +
1.423 +
1.424 +// Consumes the given substring from the iterator.
1.425 +// Returns false, if the substring does not match.
1.426 +static bool ConsumeSubString(const char** current,
1.427 + const char* end,
1.428 + const char* substring) {
1.429 + ASSERT(**current == *substring);
1.430 + for (substring++; *substring != '\0'; substring++) {
1.431 + ++*current;
1.432 + if (*current == end || **current != *substring) return false;
1.433 + }
1.434 + ++*current;
1.435 + return true;
1.436 +}
1.437 +
1.438 +
1.439 +// Maximum number of significant digits in decimal representation.
1.440 +// The longest possible double in decimal representation is
1.441 +// (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074
1.442 +// (768 digits). If we parse a number whose first digits are equal to a
1.443 +// mean of 2 adjacent doubles (that could have up to 769 digits) the result
1.444 +// must be rounded to the bigger one unless the tail consists of zeros, so
1.445 +// we don't need to preserve all the digits.
1.446 +const int kMaxSignificantDigits = 772;
1.447 +
1.448 +
1.449 +// Returns true if a nonspace found and false if the end has reached.
1.450 +static inline bool AdvanceToNonspace(const char** current, const char* end) {
1.451 + while (*current != end) {
1.452 + if (**current != ' ') return true;
1.453 + ++*current;
1.454 + }
1.455 + return false;
1.456 +}
1.457 +
1.458 +
1.459 +static bool isDigit(int x, int radix) {
1.460 + return (x >= '0' && x <= '9' && x < '0' + radix)
1.461 + || (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
1.462 + || (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
1.463 +}
1.464 +
1.465 +
1.466 +static double SignedZero(bool sign) {
1.467 + return sign ? -0.0 : 0.0;
1.468 +}
1.469 +
1.470 +
1.471 +// Parsing integers with radix 2, 4, 8, 16, 32. Assumes current != end.
1.472 +template <int radix_log_2>
1.473 +static double RadixStringToIeee(const char* current,
1.474 + const char* end,
1.475 + bool sign,
1.476 + bool allow_trailing_junk,
1.477 + double junk_string_value,
1.478 + bool read_as_double,
1.479 + const char** trailing_pointer) {
1.480 + ASSERT(current != end);
1.481 +
1.482 + const int kDoubleSize = Double::kSignificandSize;
1.483 + const int kSingleSize = Single::kSignificandSize;
1.484 + const int kSignificandSize = read_as_double? kDoubleSize: kSingleSize;
1.485 +
1.486 + // Skip leading 0s.
1.487 + while (*current == '0') {
1.488 + ++current;
1.489 + if (current == end) {
1.490 + *trailing_pointer = end;
1.491 + return SignedZero(sign);
1.492 + }
1.493 + }
1.494 +
1.495 + int64_t number = 0;
1.496 + int exponent = 0;
1.497 + const int radix = (1 << radix_log_2);
1.498 +
1.499 + do {
1.500 + int digit;
1.501 + if (*current >= '0' && *current <= '9' && *current < '0' + radix) {
1.502 + digit = static_cast<char>(*current) - '0';
1.503 + } else if (radix > 10 && *current >= 'a' && *current < 'a' + radix - 10) {
1.504 + digit = static_cast<char>(*current) - 'a' + 10;
1.505 + } else if (radix > 10 && *current >= 'A' && *current < 'A' + radix - 10) {
1.506 + digit = static_cast<char>(*current) - 'A' + 10;
1.507 + } else {
1.508 + if (allow_trailing_junk || !AdvanceToNonspace(¤t, end)) {
1.509 + break;
1.510 + } else {
1.511 + return junk_string_value;
1.512 + }
1.513 + }
1.514 +
1.515 + number = number * radix + digit;
1.516 + int overflow = static_cast<int>(number >> kSignificandSize);
1.517 + if (overflow != 0) {
1.518 + // Overflow occurred. Need to determine which direction to round the
1.519 + // result.
1.520 + int overflow_bits_count = 1;
1.521 + while (overflow > 1) {
1.522 + overflow_bits_count++;
1.523 + overflow >>= 1;
1.524 + }
1.525 +
1.526 + int dropped_bits_mask = ((1 << overflow_bits_count) - 1);
1.527 + int dropped_bits = static_cast<int>(number) & dropped_bits_mask;
1.528 + number >>= overflow_bits_count;
1.529 + exponent = overflow_bits_count;
1.530 +
1.531 + bool zero_tail = true;
1.532 + while (true) {
1.533 + ++current;
1.534 + if (current == end || !isDigit(*current, radix)) break;
1.535 + zero_tail = zero_tail && *current == '0';
1.536 + exponent += radix_log_2;
1.537 + }
1.538 +
1.539 + if (!allow_trailing_junk && AdvanceToNonspace(¤t, end)) {
1.540 + return junk_string_value;
1.541 + }
1.542 +
1.543 + int middle_value = (1 << (overflow_bits_count - 1));
1.544 + if (dropped_bits > middle_value) {
1.545 + number++; // Rounding up.
1.546 + } else if (dropped_bits == middle_value) {
1.547 + // Rounding to even to consistency with decimals: half-way case rounds
1.548 + // up if significant part is odd and down otherwise.
1.549 + if ((number & 1) != 0 || !zero_tail) {
1.550 + number++; // Rounding up.
1.551 + }
1.552 + }
1.553 +
1.554 + // Rounding up may cause overflow.
1.555 + if ((number & ((int64_t)1 << kSignificandSize)) != 0) {
1.556 + exponent++;
1.557 + number >>= 1;
1.558 + }
1.559 + break;
1.560 + }
1.561 + ++current;
1.562 + } while (current != end);
1.563 +
1.564 + ASSERT(number < ((int64_t)1 << kSignificandSize));
1.565 + ASSERT(static_cast<int64_t>(static_cast<double>(number)) == number);
1.566 +
1.567 + *trailing_pointer = current;
1.568 +
1.569 + if (exponent == 0) {
1.570 + if (sign) {
1.571 + if (number == 0) return -0.0;
1.572 + number = -number;
1.573 + }
1.574 + return static_cast<double>(number);
1.575 + }
1.576 +
1.577 + ASSERT(number != 0);
1.578 + return Double(DiyFp(number, exponent)).value();
1.579 +}
1.580 +
1.581 +
1.582 +double StringToDoubleConverter::StringToIeee(
1.583 + const char* input,
1.584 + int length,
1.585 + int* processed_characters_count,
1.586 + bool read_as_double) const {
1.587 + const char* current = input;
1.588 + const char* end = input + length;
1.589 +
1.590 + *processed_characters_count = 0;
1.591 +
1.592 + const bool allow_trailing_junk = (flags_ & ALLOW_TRAILING_JUNK) != 0;
1.593 + const bool allow_leading_spaces = (flags_ & ALLOW_LEADING_SPACES) != 0;
1.594 + const bool allow_trailing_spaces = (flags_ & ALLOW_TRAILING_SPACES) != 0;
1.595 + const bool allow_spaces_after_sign = (flags_ & ALLOW_SPACES_AFTER_SIGN) != 0;
1.596 +
1.597 + // To make sure that iterator dereferencing is valid the following
1.598 + // convention is used:
1.599 + // 1. Each '++current' statement is followed by check for equality to 'end'.
1.600 + // 2. If AdvanceToNonspace returned false then current == end.
1.601 + // 3. If 'current' becomes equal to 'end' the function returns or goes to
1.602 + // 'parsing_done'.
1.603 + // 4. 'current' is not dereferenced after the 'parsing_done' label.
1.604 + // 5. Code before 'parsing_done' may rely on 'current != end'.
1.605 + if (current == end) return empty_string_value_;
1.606 +
1.607 + if (allow_leading_spaces || allow_trailing_spaces) {
1.608 + if (!AdvanceToNonspace(¤t, end)) {
1.609 + *processed_characters_count = current - input;
1.610 + return empty_string_value_;
1.611 + }
1.612 + if (!allow_leading_spaces && (input != current)) {
1.613 + // No leading spaces allowed, but AdvanceToNonspace moved forward.
1.614 + return junk_string_value_;
1.615 + }
1.616 + }
1.617 +
1.618 + // The longest form of simplified number is: "-<significant digits>.1eXXX\0".
1.619 + const int kBufferSize = kMaxSignificantDigits + 10;
1.620 + char buffer[kBufferSize]; // NOLINT: size is known at compile time.
1.621 + int buffer_pos = 0;
1.622 +
1.623 + // Exponent will be adjusted if insignificant digits of the integer part
1.624 + // or insignificant leading zeros of the fractional part are dropped.
1.625 + int exponent = 0;
1.626 + int significant_digits = 0;
1.627 + int insignificant_digits = 0;
1.628 + bool nonzero_digit_dropped = false;
1.629 +
1.630 + bool sign = false;
1.631 +
1.632 + if (*current == '+' || *current == '-') {
1.633 + sign = (*current == '-');
1.634 + ++current;
1.635 + const char* next_non_space = current;
1.636 + // Skip following spaces (if allowed).
1.637 + if (!AdvanceToNonspace(&next_non_space, end)) return junk_string_value_;
1.638 + if (!allow_spaces_after_sign && (current != next_non_space)) {
1.639 + return junk_string_value_;
1.640 + }
1.641 + current = next_non_space;
1.642 + }
1.643 +
1.644 + if (infinity_symbol_ != NULL) {
1.645 + if (*current == infinity_symbol_[0]) {
1.646 + if (!ConsumeSubString(¤t, end, infinity_symbol_)) {
1.647 + return junk_string_value_;
1.648 + }
1.649 +
1.650 + if (!(allow_trailing_spaces || allow_trailing_junk) && (current != end)) {
1.651 + return junk_string_value_;
1.652 + }
1.653 + if (!allow_trailing_junk && AdvanceToNonspace(¤t, end)) {
1.654 + return junk_string_value_;
1.655 + }
1.656 +
1.657 + ASSERT(buffer_pos == 0);
1.658 + *processed_characters_count = current - input;
1.659 + return sign ? -Double::Infinity() : Double::Infinity();
1.660 + }
1.661 + }
1.662 +
1.663 + if (nan_symbol_ != NULL) {
1.664 + if (*current == nan_symbol_[0]) {
1.665 + if (!ConsumeSubString(¤t, end, nan_symbol_)) {
1.666 + return junk_string_value_;
1.667 + }
1.668 +
1.669 + if (!(allow_trailing_spaces || allow_trailing_junk) && (current != end)) {
1.670 + return junk_string_value_;
1.671 + }
1.672 + if (!allow_trailing_junk && AdvanceToNonspace(¤t, end)) {
1.673 + return junk_string_value_;
1.674 + }
1.675 +
1.676 + ASSERT(buffer_pos == 0);
1.677 + *processed_characters_count = current - input;
1.678 + return sign ? -Double::NaN() : Double::NaN();
1.679 + }
1.680 + }
1.681 +
1.682 + bool leading_zero = false;
1.683 + if (*current == '0') {
1.684 + ++current;
1.685 + if (current == end) {
1.686 + *processed_characters_count = current - input;
1.687 + return SignedZero(sign);
1.688 + }
1.689 +
1.690 + leading_zero = true;
1.691 +
1.692 + // It could be hexadecimal value.
1.693 + if ((flags_ & ALLOW_HEX) && (*current == 'x' || *current == 'X')) {
1.694 + ++current;
1.695 + if (current == end || !isDigit(*current, 16)) {
1.696 + return junk_string_value_; // "0x".
1.697 + }
1.698 +
1.699 + const char* tail_pointer = NULL;
1.700 + double result = RadixStringToIeee<4>(current,
1.701 + end,
1.702 + sign,
1.703 + allow_trailing_junk,
1.704 + junk_string_value_,
1.705 + read_as_double,
1.706 + &tail_pointer);
1.707 + if (tail_pointer != NULL) {
1.708 + if (allow_trailing_spaces) AdvanceToNonspace(&tail_pointer, end);
1.709 + *processed_characters_count = tail_pointer - input;
1.710 + }
1.711 + return result;
1.712 + }
1.713 +
1.714 + // Ignore leading zeros in the integer part.
1.715 + while (*current == '0') {
1.716 + ++current;
1.717 + if (current == end) {
1.718 + *processed_characters_count = current - input;
1.719 + return SignedZero(sign);
1.720 + }
1.721 + }
1.722 + }
1.723 +
1.724 + bool octal = leading_zero && (flags_ & ALLOW_OCTALS) != 0;
1.725 +
1.726 + // Copy significant digits of the integer part (if any) to the buffer.
1.727 + while (*current >= '0' && *current <= '9') {
1.728 + if (significant_digits < kMaxSignificantDigits) {
1.729 + ASSERT(buffer_pos < kBufferSize);
1.730 + buffer[buffer_pos++] = static_cast<char>(*current);
1.731 + significant_digits++;
1.732 + // Will later check if it's an octal in the buffer.
1.733 + } else {
1.734 + insignificant_digits++; // Move the digit into the exponential part.
1.735 + nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
1.736 + }
1.737 + octal = octal && *current < '8';
1.738 + ++current;
1.739 + if (current == end) goto parsing_done;
1.740 + }
1.741 +
1.742 + if (significant_digits == 0) {
1.743 + octal = false;
1.744 + }
1.745 +
1.746 + if (*current == '.') {
1.747 + if (octal && !allow_trailing_junk) return junk_string_value_;
1.748 + if (octal) goto parsing_done;
1.749 +
1.750 + ++current;
1.751 + if (current == end) {
1.752 + if (significant_digits == 0 && !leading_zero) {
1.753 + return junk_string_value_;
1.754 + } else {
1.755 + goto parsing_done;
1.756 + }
1.757 + }
1.758 +
1.759 + if (significant_digits == 0) {
1.760 + // octal = false;
1.761 + // Integer part consists of 0 or is absent. Significant digits start after
1.762 + // leading zeros (if any).
1.763 + while (*current == '0') {
1.764 + ++current;
1.765 + if (current == end) {
1.766 + *processed_characters_count = current - input;
1.767 + return SignedZero(sign);
1.768 + }
1.769 + exponent--; // Move this 0 into the exponent.
1.770 + }
1.771 + }
1.772 +
1.773 + // There is a fractional part.
1.774 + // We don't emit a '.', but adjust the exponent instead.
1.775 + while (*current >= '0' && *current <= '9') {
1.776 + if (significant_digits < kMaxSignificantDigits) {
1.777 + ASSERT(buffer_pos < kBufferSize);
1.778 + buffer[buffer_pos++] = static_cast<char>(*current);
1.779 + significant_digits++;
1.780 + exponent--;
1.781 + } else {
1.782 + // Ignore insignificant digits in the fractional part.
1.783 + nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
1.784 + }
1.785 + ++current;
1.786 + if (current == end) goto parsing_done;
1.787 + }
1.788 + }
1.789 +
1.790 + if (!leading_zero && exponent == 0 && significant_digits == 0) {
1.791 + // If leading_zeros is true then the string contains zeros.
1.792 + // If exponent < 0 then string was [+-]\.0*...
1.793 + // If significant_digits != 0 the string is not equal to 0.
1.794 + // Otherwise there are no digits in the string.
1.795 + return junk_string_value_;
1.796 + }
1.797 +
1.798 + // Parse exponential part.
1.799 + if (*current == 'e' || *current == 'E') {
1.800 + if (octal && !allow_trailing_junk) return junk_string_value_;
1.801 + if (octal) goto parsing_done;
1.802 + ++current;
1.803 + if (current == end) {
1.804 + if (allow_trailing_junk) {
1.805 + goto parsing_done;
1.806 + } else {
1.807 + return junk_string_value_;
1.808 + }
1.809 + }
1.810 + char sign = '+';
1.811 + if (*current == '+' || *current == '-') {
1.812 + sign = static_cast<char>(*current);
1.813 + ++current;
1.814 + if (current == end) {
1.815 + if (allow_trailing_junk) {
1.816 + goto parsing_done;
1.817 + } else {
1.818 + return junk_string_value_;
1.819 + }
1.820 + }
1.821 + }
1.822 +
1.823 + if (current == end || *current < '0' || *current > '9') {
1.824 + if (allow_trailing_junk) {
1.825 + goto parsing_done;
1.826 + } else {
1.827 + return junk_string_value_;
1.828 + }
1.829 + }
1.830 +
1.831 + const int max_exponent = INT_MAX / 2;
1.832 + ASSERT(-max_exponent / 2 <= exponent && exponent <= max_exponent / 2);
1.833 + int num = 0;
1.834 + do {
1.835 + // Check overflow.
1.836 + int digit = *current - '0';
1.837 + if (num >= max_exponent / 10
1.838 + && !(num == max_exponent / 10 && digit <= max_exponent % 10)) {
1.839 + num = max_exponent;
1.840 + } else {
1.841 + num = num * 10 + digit;
1.842 + }
1.843 + ++current;
1.844 + } while (current != end && *current >= '0' && *current <= '9');
1.845 +
1.846 + exponent += (sign == '-' ? -num : num);
1.847 + }
1.848 +
1.849 + if (!(allow_trailing_spaces || allow_trailing_junk) && (current != end)) {
1.850 + return junk_string_value_;
1.851 + }
1.852 + if (!allow_trailing_junk && AdvanceToNonspace(¤t, end)) {
1.853 + return junk_string_value_;
1.854 + }
1.855 + if (allow_trailing_spaces) {
1.856 + AdvanceToNonspace(¤t, end);
1.857 + }
1.858 +
1.859 + parsing_done:
1.860 + exponent += insignificant_digits;
1.861 +
1.862 + if (octal) {
1.863 + double result;
1.864 + const char* tail_pointer = NULL;
1.865 + result = RadixStringToIeee<3>(buffer,
1.866 + buffer + buffer_pos,
1.867 + sign,
1.868 + allow_trailing_junk,
1.869 + junk_string_value_,
1.870 + read_as_double,
1.871 + &tail_pointer);
1.872 + ASSERT(tail_pointer != NULL);
1.873 + *processed_characters_count = current - input;
1.874 + return result;
1.875 + }
1.876 +
1.877 + if (nonzero_digit_dropped) {
1.878 + buffer[buffer_pos++] = '1';
1.879 + exponent--;
1.880 + }
1.881 +
1.882 + ASSERT(buffer_pos < kBufferSize);
1.883 + buffer[buffer_pos] = '\0';
1.884 +
1.885 + double converted;
1.886 + if (read_as_double) {
1.887 + converted = Strtod(Vector<const char>(buffer, buffer_pos), exponent);
1.888 + } else {
1.889 + converted = Strtof(Vector<const char>(buffer, buffer_pos), exponent);
1.890 + }
1.891 + *processed_characters_count = current - input;
1.892 + return sign? -converted: converted;
1.893 +}
1.894 +
1.895 +} // namespace double_conversion
