blob: 1e2bb20c4f896882b2145489ad3736a91513ee02 [file] [log] [blame]
// Copyright 2006-2008 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include <stdarg.h>
#include <limits.h>
#include "v8.h"
#include "conversions-inl.h"
#include "dtoa.h"
#include "factory.h"
#include "scanner.h"
namespace v8 {
namespace internal {
int HexValue(uc32 c) {
if ('0' <= c && c <= '9')
return c - '0';
if ('a' <= c && c <= 'f')
return c - 'a' + 10;
if ('A' <= c && c <= 'F')
return c - 'A' + 10;
return -1;
}
namespace {
// C++-style iterator adaptor for StringInputBuffer
// (unlike C++ iterators the end-marker has different type).
class StringInputBufferIterator {
public:
class EndMarker {};
explicit StringInputBufferIterator(StringInputBuffer* buffer);
int operator*() const;
void operator++();
bool operator==(EndMarker const&) const { return end_; }
bool operator!=(EndMarker const& m) const { return !end_; }
private:
StringInputBuffer* const buffer_;
int current_;
bool end_;
};
StringInputBufferIterator::StringInputBufferIterator(
StringInputBuffer* buffer) : buffer_(buffer) {
++(*this);
}
int StringInputBufferIterator::operator*() const {
return current_;
}
void StringInputBufferIterator::operator++() {
end_ = !buffer_->has_more();
if (!end_) {
current_ = buffer_->GetNext();
}
}
}
template <class Iterator, class EndMark>
static bool SubStringEquals(Iterator* current,
EndMark end,
const char* substring) {
ASSERT(**current == *substring);
for (substring++; *substring != '\0'; substring++) {
++*current;
if (*current == end || **current != *substring) return false;
}
++*current;
return true;
}
extern "C" double gay_strtod(const char* s00, const char** se);
// Maximum number of significant digits in decimal representation.
// The longest possible double in decimal representation is
// (2^53 - 1) * 2 ^ -1074 that is (2 ^ 53 - 1) * 5 ^ 1074 / 10 ^ 1074
// (768 digits). If we parse a number whose first digits are equal to a
// mean of 2 adjacent doubles (that could have up to 769 digits) the result
// must be rounded to the bigger one unless the tail consists of zeros, so
// we don't need to preserve all the digits.
const int kMaxSignificantDigits = 772;
static const double JUNK_STRING_VALUE = OS::nan_value();
// Returns true if a nonspace found and false if the end has reached.
template <class Iterator, class EndMark>
static inline bool AdvanceToNonspace(Iterator* current, EndMark end) {
while (*current != end) {
if (!Scanner::kIsWhiteSpace.get(**current)) return true;
++*current;
}
return false;
}
static bool isDigit(int x, int radix) {
return (x >= '0' && x <= '9' && x < '0' + radix)
|| (radix > 10 && x >= 'a' && x < 'a' + radix - 10)
|| (radix > 10 && x >= 'A' && x < 'A' + radix - 10);
}
static double SignedZero(bool sign) {
return sign ? -0.0 : 0.0;
}
// Parsing integers with radix 2, 4, 8, 16, 32. Assumes current != end.
template <int radix_log_2, class Iterator, class EndMark>
static double InternalStringToIntDouble(Iterator current,
EndMark end,
bool sign,
bool allow_trailing_junk) {
ASSERT(current != end);
// Skip leading 0s.
while (*current == '0') {
++current;
if (current == end) return SignedZero(sign);
}
int64_t number = 0;
int exponent = 0;
const int radix = (1 << radix_log_2);
do {
int digit;
if (*current >= '0' && *current <= '9' && *current < '0' + radix) {
digit = static_cast<char>(*current) - '0';
} else if (radix > 10 && *current >= 'a' && *current < 'a' + radix - 10) {
digit = static_cast<char>(*current) - 'a' + 10;
} else if (radix > 10 && *current >= 'A' && *current < 'A' + radix - 10) {
digit = static_cast<char>(*current) - 'A' + 10;
} else {
if (allow_trailing_junk || !AdvanceToNonspace(&current, end)) {
break;
} else {
return JUNK_STRING_VALUE;
}
}
number = number * radix + digit;
int overflow = static_cast<int>(number >> 53);
if (overflow != 0) {
// Overflow occurred. Need to determine which direction to round the
// result.
int overflow_bits_count = 1;
while (overflow > 1) {
overflow_bits_count++;
overflow >>= 1;
}
int dropped_bits_mask = ((1 << overflow_bits_count) - 1);
int dropped_bits = static_cast<int>(number) & dropped_bits_mask;
number >>= overflow_bits_count;
exponent = overflow_bits_count;
bool zero_tail = true;
while (true) {
++current;
if (current == end || !isDigit(*current, radix)) break;
zero_tail = zero_tail && *current == '0';
exponent += radix_log_2;
}
if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
return JUNK_STRING_VALUE;
}
int middle_value = (1 << (overflow_bits_count - 1));
if (dropped_bits > middle_value) {
number++; // Rounding up.
} else if (dropped_bits == middle_value) {
// Rounding to even to consistency with decimals: half-way case rounds
// up if significant part is odd and down otherwise.
if ((number & 1) != 0 || !zero_tail) {
number++; // Rounding up.
}
}
// Rounding up may cause overflow.
if ((number & ((int64_t)1 << 53)) != 0) {
exponent++;
number >>= 1;
}
break;
}
++current;
} while (current != end);
ASSERT(number < ((int64_t)1 << 53));
ASSERT(static_cast<int64_t>(static_cast<double>(number)) == number);
if (exponent == 0) {
if (sign) {
if (number == 0) return -0.0;
number = -number;
}
return static_cast<double>(number);
}
ASSERT(number != 0);
// The double could be constructed faster from number (mantissa), exponent
// and sign. Assuming it's a rare case more simple code is used.
return static_cast<double>(sign ? -number : number) * pow(2.0, exponent);
}
template <class Iterator, class EndMark>
static double InternalStringToInt(Iterator current, EndMark end, int radix) {
const bool allow_trailing_junk = true;
const double empty_string_val = JUNK_STRING_VALUE;
if (!AdvanceToNonspace(&current, end)) return empty_string_val;
bool sign = false;
bool leading_zero = false;
if (*current == '+') {
// Ignore leading sign; skip following spaces.
++current;
if (!AdvanceToNonspace(&current, end)) return JUNK_STRING_VALUE;
} else if (*current == '-') {
++current;
if (!AdvanceToNonspace(&current, end)) return JUNK_STRING_VALUE;
sign = true;
}
if (radix == 0) {
// Radix detection.
if (*current == '0') {
++current;
if (current == end) return SignedZero(sign);
if (*current == 'x' || *current == 'X') {
radix = 16;
++current;
if (current == end) return JUNK_STRING_VALUE;
} else {
radix = 8;
leading_zero = true;
}
} else {
radix = 10;
}
} else if (radix == 16) {
if (*current == '0') {
// Allow "0x" prefix.
++current;
if (current == end) return SignedZero(sign);
if (*current == 'x' || *current == 'X') {
++current;
if (current == end) return JUNK_STRING_VALUE;
} else {
leading_zero = true;
}
}
}
if (radix < 2 || radix > 36) return JUNK_STRING_VALUE;
// Skip leading zeros.
while (*current == '0') {
leading_zero = true;
++current;
if (current == end) return SignedZero(sign);
}
if (!leading_zero && !isDigit(*current, radix)) {
return JUNK_STRING_VALUE;
}
if (IsPowerOf2(radix)) {
switch (radix) {
case 2:
return InternalStringToIntDouble<1>(
current, end, sign, allow_trailing_junk);
case 4:
return InternalStringToIntDouble<2>(
current, end, sign, allow_trailing_junk);
case 8:
return InternalStringToIntDouble<3>(
current, end, sign, allow_trailing_junk);
case 16:
return InternalStringToIntDouble<4>(
current, end, sign, allow_trailing_junk);
case 32:
return InternalStringToIntDouble<5>(
current, end, sign, allow_trailing_junk);
default:
UNREACHABLE();
}
}
if (radix == 10) {
// Parsing with strtod.
const int kMaxSignificantDigits = 309; // Doubles are less than 1.8e308.
// The buffer may contain up to kMaxSignificantDigits + 1 digits and a zero
// end.
const int kBufferSize = kMaxSignificantDigits + 2;
char buffer[kBufferSize];
int buffer_pos = 0;
while (*current >= '0' && *current <= '9') {
if (buffer_pos <= kMaxSignificantDigits) {
// If the number has more than kMaxSignificantDigits it will be parsed
// as infinity.
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos++] = static_cast<char>(*current);
}
++current;
if (current == end) break;
}
if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
return JUNK_STRING_VALUE;
}
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos++] = '\0';
return sign ? -gay_strtod(buffer, NULL) : gay_strtod(buffer, NULL);
}
// The following code causes accumulating rounding error for numbers greater
// than ~2^56. It's explicitly allowed in the spec: "if R is not 2, 4, 8, 10,
// 16, or 32, then mathInt may be an implementation-dependent approximation to
// the mathematical integer value" (15.1.2.2).
int lim_0 = '0' + (radix < 10 ? radix : 10);
int lim_a = 'a' + (radix - 10);
int lim_A = 'A' + (radix - 10);
// NOTE: The code for computing the value may seem a bit complex at
// first glance. It is structured to use 32-bit multiply-and-add
// loops as long as possible to avoid loosing precision.
double v = 0.0;
bool done = false;
do {
// Parse the longest part of the string starting at index j
// possible while keeping the multiplier, and thus the part
// itself, within 32 bits.
unsigned int part = 0, multiplier = 1;
while (true) {
int d;
if (*current >= '0' && *current < lim_0) {
d = *current - '0';
} else if (*current >= 'a' && *current < lim_a) {
d = *current - 'a' + 10;
} else if (*current >= 'A' && *current < lim_A) {
d = *current - 'A' + 10;
} else {
done = true;
break;
}
// Update the value of the part as long as the multiplier fits
// in 32 bits. When we can't guarantee that the next iteration
// will not overflow the multiplier, we stop parsing the part
// by leaving the loop.
const unsigned int kMaximumMultiplier = 0xffffffffU / 36;
uint32_t m = multiplier * radix;
if (m > kMaximumMultiplier) break;
part = part * radix + d;
multiplier = m;
ASSERT(multiplier > part);
++current;
if (current == end) {
done = true;
break;
}
}
// Update the value and skip the part in the string.
v = v * multiplier + part;
} while (!done);
if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
return JUNK_STRING_VALUE;
}
return sign ? -v : v;
}
// Converts a string to a double value. Assumes the Iterator supports
// the following operations:
// 1. current == end (other ops are not allowed), current != end.
// 2. *current - gets the current character in the sequence.
// 3. ++current (advances the position).
template <class Iterator, class EndMark>
static double InternalStringToDouble(Iterator current,
EndMark end,
int flags,
double empty_string_val) {
// To make sure that iterator dereferencing is valid the following
// convention is used:
// 1. Each '++current' statement is followed by check for equality to 'end'.
// 2. If AdvanceToNonspace returned false then current == end.
// 3. If 'current' becomes be equal to 'end' the function returns or goes to
// 'parsing_done'.
// 4. 'current' is not dereferenced after the 'parsing_done' label.
// 5. Code before 'parsing_done' may rely on 'current != end'.
if (!AdvanceToNonspace(&current, end)) return empty_string_val;
const bool allow_trailing_junk = (flags & ALLOW_TRAILING_JUNK) != 0;
// The longest form of simplified number is: "-<significant digits>'.1eXXX\0".
const int kBufferSize = kMaxSignificantDigits + 10;
char buffer[kBufferSize]; // NOLINT: size is known at compile time.
int buffer_pos = 0;
// Exponent will be adjusted if insignificant digits of the integer part
// or insignificant leading zeros of the fractional part are dropped.
int exponent = 0;
int significant_digits = 0;
int insignificant_digits = 0;
bool nonzero_digit_dropped = false;
bool fractional_part = false;
bool sign = false;
if (*current == '+') {
// Ignore leading sign; skip following spaces.
++current;
if (!AdvanceToNonspace(&current, end)) return JUNK_STRING_VALUE;
} else if (*current == '-') {
buffer[buffer_pos++] = '-';
++current;
if (!AdvanceToNonspace(&current, end)) return JUNK_STRING_VALUE;
sign = true;
}
static const char kInfinitySymbol[] = "Infinity";
if (*current == kInfinitySymbol[0]) {
if (!SubStringEquals(&current, end, kInfinitySymbol)) {
return JUNK_STRING_VALUE;
}
if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
return JUNK_STRING_VALUE;
}
ASSERT(buffer_pos == 0 || buffer[0] == '-');
return buffer_pos > 0 ? -V8_INFINITY : V8_INFINITY;
}
bool leading_zero = false;
if (*current == '0') {
++current;
if (current == end) return SignedZero(sign);
leading_zero = true;
// It could be hexadecimal value.
if ((flags & ALLOW_HEX) && (*current == 'x' || *current == 'X')) {
++current;
if (current == end || !isDigit(*current, 16)) {
return JUNK_STRING_VALUE; // "0x".
}
bool sign = (buffer_pos > 0 && buffer[0] == '-');
return InternalStringToIntDouble<4>(current,
end,
sign,
allow_trailing_junk);
}
// Ignore leading zeros in the integer part.
while (*current == '0') {
++current;
if (current == end) return SignedZero(sign);
}
}
bool octal = leading_zero && (flags & ALLOW_OCTALS) != 0;
// Copy significant digits of the integer part (if any) to the buffer.
while (*current >= '0' && *current <= '9') {
if (significant_digits < kMaxSignificantDigits) {
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos++] = static_cast<char>(*current);
significant_digits++;
// Will later check if it's an octal in the buffer.
} else {
insignificant_digits++; // Move the digit into the exponential part.
nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
}
octal = octal && *current < '8';
++current;
if (current == end) goto parsing_done;
}
if (significant_digits == 0) {
octal = false;
}
if (*current == '.') {
++current;
if (current == end) {
if (significant_digits == 0 && !leading_zero) {
return JUNK_STRING_VALUE;
} else {
goto parsing_done;
}
}
if (significant_digits == 0) {
// octal = false;
// Integer part consists of 0 or is absent. Significant digits start after
// leading zeros (if any).
while (*current == '0') {
++current;
if (current == end) return SignedZero(sign);
exponent--; // Move this 0 into the exponent.
}
}
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos++] = '.';
fractional_part = true;
// There is the fractional part.
while (*current >= '0' && *current <= '9') {
if (significant_digits < kMaxSignificantDigits) {
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos++] = static_cast<char>(*current);
significant_digits++;
} else {
// Ignore insignificant digits in the fractional part.
nonzero_digit_dropped = nonzero_digit_dropped || *current != '0';
}
++current;
if (current == end) goto parsing_done;
}
}
if (!leading_zero && exponent == 0 && significant_digits == 0) {
// If leading_zeros is true then the string contains zeros.
// If exponent < 0 then string was [+-]\.0*...
// If significant_digits != 0 the string is not equal to 0.
// Otherwise there are no digits in the string.
return JUNK_STRING_VALUE;
}
// Parse exponential part.
if (*current == 'e' || *current == 'E') {
if (octal) return JUNK_STRING_VALUE;
++current;
if (current == end) {
if (allow_trailing_junk) {
goto parsing_done;
} else {
return JUNK_STRING_VALUE;
}
}
char sign = '+';
if (*current == '+' || *current == '-') {
sign = static_cast<char>(*current);
++current;
if (current == end) {
if (allow_trailing_junk) {
goto parsing_done;
} else {
return JUNK_STRING_VALUE;
}
}
}
if (current == end || *current < '0' || *current > '9') {
if (allow_trailing_junk) {
goto parsing_done;
} else {
return JUNK_STRING_VALUE;
}
}
const int max_exponent = INT_MAX / 2;
ASSERT(-max_exponent / 2 <= exponent && exponent <= max_exponent / 2);
int num = 0;
do {
// Check overflow.
int digit = *current - '0';
if (num >= max_exponent / 10
&& !(num == max_exponent / 10 && digit <= max_exponent % 10)) {
num = max_exponent;
} else {
num = num * 10 + digit;
}
++current;
} while (current != end && *current >= '0' && *current <= '9');
exponent += (sign == '-' ? -num : num);
}
if (!allow_trailing_junk && AdvanceToNonspace(&current, end)) {
return JUNK_STRING_VALUE;
}
parsing_done:
exponent += insignificant_digits;
if (octal) {
bool sign = buffer[0] == '-';
int start_pos = (sign ? 1 : 0);
return InternalStringToIntDouble<3>(buffer + start_pos,
buffer + buffer_pos,
sign,
allow_trailing_junk);
}
if (nonzero_digit_dropped) {
if (insignificant_digits) buffer[buffer_pos++] = '.';
buffer[buffer_pos++] = '1';
}
// If the number has no more than kMaxDigitsInInt digits and doesn't have
// fractional part it could be parsed faster (without checks for
// spaces, overflow, etc.).
const int kMaxDigitsInInt = 9 * sizeof(int) / 4; // NOLINT
if (exponent != 0) {
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos++] = 'e';
if (exponent < 0) {
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos++] = '-';
exponent = -exponent;
}
if (exponent > 999) exponent = 999; // Result will be Infinity or 0 or -0.
const int exp_digits = 3;
for (int i = 0; i < exp_digits; i++) {
buffer[buffer_pos + exp_digits - 1 - i] = '0' + exponent % 10;
exponent /= 10;
}
ASSERT(exponent == 0);
buffer_pos += exp_digits;
} else if (!fractional_part && significant_digits <= kMaxDigitsInInt) {
if (significant_digits == 0) return SignedZero(sign);
ASSERT(buffer_pos > 0);
int num = 0;
int start_pos = (buffer[0] == '-' ? 1 : 0);
for (int i = start_pos; i < buffer_pos; i++) {
ASSERT(buffer[i] >= '0' && buffer[i] <= '9');
num = 10 * num + (buffer[i] - '0');
}
return static_cast<double>(start_pos == 0 ? num : -num);
}
ASSERT(buffer_pos < kBufferSize);
buffer[buffer_pos] = '\0';
return gay_strtod(buffer, NULL);
}
double StringToDouble(String* str, int flags, double empty_string_val) {
StringShape shape(str);
if (shape.IsSequentialAscii()) {
const char* begin = SeqAsciiString::cast(str)->GetChars();
const char* end = begin + str->length();
return InternalStringToDouble(begin, end, flags, empty_string_val);
} else if (shape.IsSequentialTwoByte()) {
const uc16* begin = SeqTwoByteString::cast(str)->GetChars();
const uc16* end = begin + str->length();
return InternalStringToDouble(begin, end, flags, empty_string_val);
} else {
StringInputBuffer buffer(str);
return InternalStringToDouble(StringInputBufferIterator(&buffer),
StringInputBufferIterator::EndMarker(),
flags,
empty_string_val);
}
}
double StringToInt(String* str, int radix) {
StringShape shape(str);
if (shape.IsSequentialAscii()) {
const char* begin = SeqAsciiString::cast(str)->GetChars();
const char* end = begin + str->length();
return InternalStringToInt(begin, end, radix);
} else if (shape.IsSequentialTwoByte()) {
const uc16* begin = SeqTwoByteString::cast(str)->GetChars();
const uc16* end = begin + str->length();
return InternalStringToInt(begin, end, radix);
} else {
StringInputBuffer buffer(str);
return InternalStringToInt(StringInputBufferIterator(&buffer),
StringInputBufferIterator::EndMarker(),
radix);
}
}
double StringToDouble(const char* str, int flags, double empty_string_val) {
const char* end = str + StrLength(str);
return InternalStringToDouble(str, end, flags, empty_string_val);
}
extern "C" char* dtoa(double d, int mode, int ndigits,
int* decpt, int* sign, char** rve);
extern "C" void freedtoa(char* s);
const char* DoubleToCString(double v, Vector<char> buffer) {
StringBuilder builder(buffer.start(), buffer.length());
switch (fpclassify(v)) {
case FP_NAN:
builder.AddString("NaN");
break;
case FP_INFINITE:
if (v < 0.0) {
builder.AddString("-Infinity");
} else {
builder.AddString("Infinity");
}
break;
case FP_ZERO:
builder.AddCharacter('0');
break;
default: {
int decimal_point;
int sign;
char* decimal_rep;
bool used_gay_dtoa = false;
const int kV8DtoaBufferCapacity = kBase10MaximalLength + 1;
char v8_dtoa_buffer[kV8DtoaBufferCapacity];
int length;
if (DoubleToAscii(v, DTOA_SHORTEST, 0,
Vector<char>(v8_dtoa_buffer, kV8DtoaBufferCapacity),
&sign, &length, &decimal_point)) {
decimal_rep = v8_dtoa_buffer;
} else {
decimal_rep = dtoa(v, 0, 0, &decimal_point, &sign, NULL);
used_gay_dtoa = true;
length = StrLength(decimal_rep);
}
if (sign) builder.AddCharacter('-');
if (length <= decimal_point && decimal_point <= 21) {
// ECMA-262 section 9.8.1 step 6.
builder.AddString(decimal_rep);
builder.AddPadding('0', decimal_point - length);
} else if (0 < decimal_point && decimal_point <= 21) {
// ECMA-262 section 9.8.1 step 7.
builder.AddSubstring(decimal_rep, decimal_point);
builder.AddCharacter('.');
builder.AddString(decimal_rep + decimal_point);
} else if (decimal_point <= 0 && decimal_point > -6) {
// ECMA-262 section 9.8.1 step 8.
builder.AddString("0.");
builder.AddPadding('0', -decimal_point);
builder.AddString(decimal_rep);
} else {
// ECMA-262 section 9.8.1 step 9 and 10 combined.
builder.AddCharacter(decimal_rep[0]);
if (length != 1) {
builder.AddCharacter('.');
builder.AddString(decimal_rep + 1);
}
builder.AddCharacter('e');
builder.AddCharacter((decimal_point >= 0) ? '+' : '-');
int exponent = decimal_point - 1;
if (exponent < 0) exponent = -exponent;
builder.AddFormatted("%d", exponent);
}
if (used_gay_dtoa) freedtoa(decimal_rep);
}
}
return builder.Finalize();
}
const char* IntToCString(int n, Vector<char> buffer) {
bool negative = false;
if (n < 0) {
// We must not negate the most negative int.
if (n == kMinInt) return DoubleToCString(n, buffer);
negative = true;
n = -n;
}
// Build the string backwards from the least significant digit.
int i = buffer.length();
buffer[--i] = '\0';
do {
buffer[--i] = '0' + (n % 10);
n /= 10;
} while (n);
if (negative) buffer[--i] = '-';
return buffer.start() + i;
}
char* DoubleToFixedCString(double value, int f) {
const int kMaxDigitsBeforePoint = 20;
const double kFirstNonFixed = 1e21;
const int kMaxDigitsAfterPoint = 20;
ASSERT(f >= 0);
ASSERT(f <= kMaxDigitsAfterPoint);
bool negative = false;
double abs_value = value;
if (value < 0) {
abs_value = -value;
negative = true;
}
// If abs_value has more than kMaxDigitsBeforePoint digits before the point
// use the non-fixed conversion routine.
if (abs_value >= kFirstNonFixed) {
char arr[100];
Vector<char> buffer(arr, ARRAY_SIZE(arr));
return StrDup(DoubleToCString(value, buffer));
}
// Find a sufficiently precise decimal representation of n.
int decimal_point;
int sign;
// Add space for the '.' and the '\0' byte.
const int kDecimalRepCapacity =
kMaxDigitsBeforePoint + kMaxDigitsAfterPoint + 2;
char decimal_rep[kDecimalRepCapacity];
int decimal_rep_length;
bool status = DoubleToAscii(value, DTOA_FIXED, f,
Vector<char>(decimal_rep, kDecimalRepCapacity),
&sign, &decimal_rep_length, &decimal_point);
USE(status);
ASSERT(status);
// Create a representation that is padded with zeros if needed.
int zero_prefix_length = 0;
int zero_postfix_length = 0;
if (decimal_point <= 0) {
zero_prefix_length = -decimal_point + 1;
decimal_point = 1;
}
if (zero_prefix_length + decimal_rep_length < decimal_point + f) {
zero_postfix_length = decimal_point + f - decimal_rep_length -
zero_prefix_length;
}
unsigned rep_length =
zero_prefix_length + decimal_rep_length + zero_postfix_length;
StringBuilder rep_builder(rep_length + 1);
rep_builder.AddPadding('0', zero_prefix_length);
rep_builder.AddString(decimal_rep);
rep_builder.AddPadding('0', zero_postfix_length);
char* rep = rep_builder.Finalize();
// Create the result string by appending a minus and putting in a
// decimal point if needed.
unsigned result_size = decimal_point + f + 2;
StringBuilder builder(result_size + 1);
if (negative) builder.AddCharacter('-');
builder.AddSubstring(rep, decimal_point);
if (f > 0) {
builder.AddCharacter('.');
builder.AddSubstring(rep + decimal_point, f);
}
DeleteArray(rep);
return builder.Finalize();
}
static char* CreateExponentialRepresentation(char* decimal_rep,
int exponent,
bool negative,
int significant_digits) {
bool negative_exponent = false;
if (exponent < 0) {
negative_exponent = true;
exponent = -exponent;
}
// Leave room in the result for appending a minus, for a period, the
// letter 'e', a minus or a plus depending on the exponent, and a
// three digit exponent.
unsigned result_size = significant_digits + 7;
StringBuilder builder(result_size + 1);
if (negative) builder.AddCharacter('-');
builder.AddCharacter(decimal_rep[0]);
if (significant_digits != 1) {
builder.AddCharacter('.');
builder.AddString(decimal_rep + 1);
int rep_length = StrLength(decimal_rep);
builder.AddPadding('0', significant_digits - rep_length);
}
builder.AddCharacter('e');
builder.AddCharacter(negative_exponent ? '-' : '+');
builder.AddFormatted("%d", exponent);
return builder.Finalize();
}
char* DoubleToExponentialCString(double value, int f) {
// f might be -1 to signal that f was undefined in JavaScript.
ASSERT(f >= -1 && f <= 20);
bool negative = false;
if (value < 0) {
value = -value;
negative = true;
}
// Find a sufficiently precise decimal representation of n.
int decimal_point;
int sign;
char* decimal_rep = NULL;
if (f == -1) {
decimal_rep = dtoa(value, 0, 0, &decimal_point, &sign, NULL);
f = StrLength(decimal_rep) - 1;
} else {
decimal_rep = dtoa(value, 2, f + 1, &decimal_point, &sign, NULL);
}
int decimal_rep_length = StrLength(decimal_rep);
ASSERT(decimal_rep_length > 0);
ASSERT(decimal_rep_length <= f + 1);
USE(decimal_rep_length);
int exponent = decimal_point - 1;
char* result =
CreateExponentialRepresentation(decimal_rep, exponent, negative, f+1);
freedtoa(decimal_rep);
return result;
}
char* DoubleToPrecisionCString(double value, int p) {
ASSERT(p >= 1 && p <= 21);
bool negative = false;
if (value < 0) {
value = -value;
negative = true;
}
// Find a sufficiently precise decimal representation of n.
int decimal_point;
int sign;
char* decimal_rep = dtoa(value, 2, p, &decimal_point, &sign, NULL);
int decimal_rep_length = StrLength(decimal_rep);
ASSERT(decimal_rep_length <= p);
int exponent = decimal_point - 1;
char* result = NULL;
if (exponent < -6 || exponent >= p) {
result =
CreateExponentialRepresentation(decimal_rep, exponent, negative, p);
} else {
// Use fixed notation.
//
// Leave room in the result for appending a minus, a period and in
// the case where decimal_point is not positive for a zero in
// front of the period.
unsigned result_size = (decimal_point <= 0)
? -decimal_point + p + 3
: p + 2;
StringBuilder builder(result_size + 1);
if (negative) builder.AddCharacter('-');
if (decimal_point <= 0) {
builder.AddString("0.");
builder.AddPadding('0', -decimal_point);
builder.AddString(decimal_rep);
builder.AddPadding('0', p - decimal_rep_length);
} else {
const int m = Min(decimal_rep_length, decimal_point);
builder.AddSubstring(decimal_rep, m);
builder.AddPadding('0', decimal_point - decimal_rep_length);
if (decimal_point < p) {
builder.AddCharacter('.');
const int extra = negative ? 2 : 1;
if (decimal_rep_length > decimal_point) {
const int len = StrLength(decimal_rep + decimal_point);
const int n = Min(len, p - (builder.position() - extra));
builder.AddSubstring(decimal_rep + decimal_point, n);
}
builder.AddPadding('0', extra + (p - builder.position()));
}
}
result = builder.Finalize();
}
freedtoa(decimal_rep);
return result;
}
char* DoubleToRadixCString(double value, int radix) {
ASSERT(radix >= 2 && radix <= 36);
// Character array used for conversion.
static const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyz";
// Buffer for the integer part of the result. 1024 chars is enough
// for max integer value in radix 2. We need room for a sign too.
static const int kBufferSize = 1100;
char integer_buffer[kBufferSize];
integer_buffer[kBufferSize - 1] = '\0';
// Buffer for the decimal part of the result. We only generate up
// to kBufferSize - 1 chars for the decimal part.
char decimal_buffer[kBufferSize];
decimal_buffer[kBufferSize - 1] = '\0';
// Make sure the value is positive.
bool is_negative = value < 0.0;
if (is_negative) value = -value;
// Get the integer part and the decimal part.
double integer_part = floor(value);
double decimal_part = value - integer_part;
// Convert the integer part starting from the back. Always generate
// at least one digit.
int integer_pos = kBufferSize - 2;
do {
integer_buffer[integer_pos--] =
chars[static_cast<int>(modulo(integer_part, radix))];
integer_part /= radix;
} while (integer_part >= 1.0);
// Sanity check.
ASSERT(integer_pos > 0);
// Add sign if needed.
if (is_negative) integer_buffer[integer_pos--] = '-';
// Convert the decimal part. Repeatedly multiply by the radix to
// generate the next char. Never generate more than kBufferSize - 1
// chars.
//
// TODO(1093998): We will often generate a full decimal_buffer of
// chars because hitting zero will often not happen. The right
// solution would be to continue until the string representation can
// be read back and yield the original value. To implement this
// efficiently, we probably have to modify dtoa.
int decimal_pos = 0;
while ((decimal_part > 0.0) && (decimal_pos < kBufferSize - 1)) {
decimal_part *= radix;
decimal_buffer[decimal_pos++] =
chars[static_cast<int>(floor(decimal_part))];
decimal_part -= floor(decimal_part);
}
decimal_buffer[decimal_pos] = '\0';
// Compute the result size.
int integer_part_size = kBufferSize - 2 - integer_pos;
// Make room for zero termination.
unsigned result_size = integer_part_size + decimal_pos;
// If the number has a decimal part, leave room for the period.
if (decimal_pos > 0) result_size++;
// Allocate result and fill in the parts.
StringBuilder builder(result_size + 1);
builder.AddSubstring(integer_buffer + integer_pos + 1, integer_part_size);
if (decimal_pos > 0) builder.AddCharacter('.');
builder.AddSubstring(decimal_buffer, decimal_pos);
return builder.Finalize();
}
} } // namespace v8::internal