// Copyright 2011 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "src/conversions.h"
#include <limits.h>
#include <stdarg.h>
#include <cmath>
#include "src/allocation.h"
#include "src/assert-scope.h"
#include "src/char-predicates-inl.h"
#include "src/codegen.h"
#include "src/conversions-inl.h"
#include "src/dtoa.h"
#include "src/factory.h"
#include "src/handles.h"
#include "src/list-inl.h"
#include "src/strtod.h"
#include "src/utils.h"
#ifndef _STLP_VENDOR_CSTD
// STLPort doesn't import fpclassify into the std namespace.
using std::fpclassify;
#endif
namespace v8 {
namespace internal {
namespace {
// C++-style iterator adaptor for StringCharacterStream
// (unlike C++ iterators the end-marker has different type).
class StringCharacterStreamIterator {
public:
class EndMarker {};
explicit StringCharacterStreamIterator(StringCharacterStream* stream);
uint16_t operator*() const;
void operator++();
bool operator==(EndMarker const&) const { return end_; }
bool operator!=(EndMarker const& m) const { return !end_; }
private:
StringCharacterStream* const stream_;
uint16_t current_;
bool end_;
};
StringCharacterStreamIterator::StringCharacterStreamIterator(
StringCharacterStream* stream) : stream_(stream) {
++(*this);
}
uint16_t StringCharacterStreamIterator::operator*() const {
return current_;
}
void StringCharacterStreamIterator::operator++() {
end_ = !stream_->HasMore();
if (!end_) {
current_ = stream_->GetNext();
}
}
} // End anonymous namespace.
double StringToDouble(UnicodeCache* unicode_cache,
const char* str, int flags, double empty_string_val) {
// We cast to const uint8_t* here to avoid instantiating the
// InternalStringToDouble() template for const char* as well.
const uint8_t* start = reinterpret_cast<const uint8_t*>(str);
const uint8_t* end = start + StrLength(str);
return InternalStringToDouble(unicode_cache, start, end, flags,
empty_string_val);
}
double StringToDouble(UnicodeCache* unicode_cache,
Vector<const uint8_t> str,
int flags,
double empty_string_val) {
// We cast to const uint8_t* here to avoid instantiating the
// InternalStringToDouble() template for const char* as well.
const uint8_t* start = reinterpret_cast<const uint8_t*>(str.start());
const uint8_t* end = start + str.length();
return InternalStringToDouble(unicode_cache, start, end, flags,
empty_string_val);
}
double StringToDouble(UnicodeCache* unicode_cache,
Vector<const uc16> str,
int flags,
double empty_string_val) {
const uc16* end = str.start() + str.length();
return InternalStringToDouble(unicode_cache, str.start(), end, flags,
empty_string_val);
}
// Converts a string into an integer.
double StringToInt(UnicodeCache* unicode_cache,
Vector<const uint8_t> vector,
int radix) {
return InternalStringToInt(
unicode_cache, vector.start(), vector.start() + vector.length(), radix);
}
double StringToInt(UnicodeCache* unicode_cache,
Vector<const uc16> vector,
int radix) {
return InternalStringToInt(
unicode_cache, vector.start(), vector.start() + vector.length(), radix);
}
const char* DoubleToCString(double v, Vector<char> buffer) {
switch (fpclassify(v)) {
case FP_NAN: return "NaN";
case FP_INFINITE: return (v < 0.0 ? "-Infinity" : "Infinity");
case FP_ZERO: return "0";
default: {
SimpleStringBuilder builder(buffer.start(), buffer.length());
int decimal_point;
int sign;
const int kV8DtoaBufferCapacity = kBase10MaximalLength + 1;
char decimal_rep[kV8DtoaBufferCapacity];
int length;
DoubleToAscii(v, DTOA_SHORTEST, 0,
Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
&sign, &length, &decimal_point);
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.AddDecimalInteger(exponent);
}
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 = 21;
const double kFirstNonFixed = 1e21;
const int kMaxDigitsAfterPoint = 20;
DCHECK(f >= 0);
DCHECK(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, arraysize(arr));
return StrDup(DoubleToCString(value, buffer));
}
// Find a sufficiently precise decimal representation of n.
int decimal_point;
int sign;
// Add space for the '\0' byte.
const int kDecimalRepCapacity =
kMaxDigitsBeforePoint + kMaxDigitsAfterPoint + 1;
char decimal_rep[kDecimalRepCapacity];
int decimal_rep_length;
DoubleToAscii(value, DTOA_FIXED, f,
Vector<char>(decimal_rep, kDecimalRepCapacity),
&sign, &decimal_rep_length, &decimal_point);
// 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;
SimpleStringBuilder 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;
SimpleStringBuilder 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;
SimpleStringBuilder 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.AddDecimalInteger(exponent);
return builder.Finalize();
}
char* DoubleToExponentialCString(double value, int f) {
const int kMaxDigitsAfterPoint = 20;
// f might be -1 to signal that f was undefined in JavaScript.
DCHECK(f >= -1 && f <= kMaxDigitsAfterPoint);
bool negative = false;
if (value < 0) {
value = -value;
negative = true;
}
// Find a sufficiently precise decimal representation of n.
int decimal_point;
int sign;
// f corresponds to the digits after the point. There is always one digit
// before the point. The number of requested_digits equals hence f + 1.
// And we have to add one character for the null-terminator.
const int kV8DtoaBufferCapacity = kMaxDigitsAfterPoint + 1 + 1;
// Make sure that the buffer is big enough, even if we fall back to the
// shortest representation (which happens when f equals -1).
DCHECK(kBase10MaximalLength <= kMaxDigitsAfterPoint + 1);
char decimal_rep[kV8DtoaBufferCapacity];
int decimal_rep_length;
if (f == -1) {
DoubleToAscii(value, DTOA_SHORTEST, 0,
Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
&sign, &decimal_rep_length, &decimal_point);
f = decimal_rep_length - 1;
} else {
DoubleToAscii(value, DTOA_PRECISION, f + 1,
Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
&sign, &decimal_rep_length, &decimal_point);
}
DCHECK(decimal_rep_length > 0);
DCHECK(decimal_rep_length <= f + 1);
int exponent = decimal_point - 1;
char* result =
CreateExponentialRepresentation(decimal_rep, exponent, negative, f+1);
return result;
}
char* DoubleToPrecisionCString(double value, int p) {
const int kMinimalDigits = 1;
const int kMaximalDigits = 21;
DCHECK(p >= kMinimalDigits && p <= kMaximalDigits);
USE(kMinimalDigits);
bool negative = false;
if (value < 0) {
value = -value;
negative = true;
}
// Find a sufficiently precise decimal representation of n.
int decimal_point;
int sign;
// Add one for the terminating null character.
const int kV8DtoaBufferCapacity = kMaximalDigits + 1;
char decimal_rep[kV8DtoaBufferCapacity];
int decimal_rep_length;
DoubleToAscii(value, DTOA_PRECISION, p,
Vector<char>(decimal_rep, kV8DtoaBufferCapacity),
&sign, &decimal_rep_length, &decimal_point);
DCHECK(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;
SimpleStringBuilder 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();
}
return result;
}
char* DoubleToRadixCString(double value, int radix) {
DCHECK(radix >= 2 && radix <= 36);
DCHECK(std::isfinite(value));
DCHECK_NE(0.0, value);
// Character array used for conversion.
static const char chars[] = "0123456789abcdefghijklmnopqrstuvwxyz";
// Temporary buffer for the result. We start with the decimal point in the
// middle and write to the left for the integer part and to the right for the
// fractional part. 1024 characters for the exponent and 52 for the mantissa
// either way, with additional space for sign, decimal point and string
// termination should be sufficient.
static const int kBufferSize = 2200;
char buffer[kBufferSize];
int integer_cursor = kBufferSize / 2;
int fraction_cursor = integer_cursor;
bool negative = value < 0;
if (negative) value = -value;
// Split the value into an integer part and a fractional part.
double integer = std::floor(value);
double fraction = value - integer;
// We only compute fractional digits up to the input double's precision.
double delta = 0.5 * (Double(value).NextDouble() - value);
delta = std::max(Double(0.0).NextDouble(), delta);
DCHECK_GT(delta, 0.0);
if (fraction > delta) {
// Insert decimal point.
buffer[fraction_cursor++] = '.';
do {
// Shift up by one digit.
fraction *= radix;
delta *= radix;
// Write digit.
int digit = static_cast<int>(fraction);
buffer[fraction_cursor++] = chars[digit];
// Calculate remainder.
fraction -= digit;
// Round to even.
if (fraction > 0.5 || (fraction == 0.5 && (digit & 1))) {
if (fraction + delta > 1) {
// We need to back trace already written digits in case of carry-over.
while (true) {
fraction_cursor--;
if (fraction_cursor == kBufferSize / 2) {
CHECK_EQ('.', buffer[fraction_cursor]);
// Carry over to the integer part.
integer += 1;
break;
}
char c = buffer[fraction_cursor];
// Reconstruct digit.
int digit = c > '9' ? (c - 'a' + 10) : (c - '0');
if (digit + 1 < radix) {
buffer[fraction_cursor++] = chars[digit + 1];
break;
}
}
break;
}
}
} while (fraction > delta);
}
// Compute integer digits. Fill unrepresented digits with zero.
while (Double(integer / radix).Exponent() > 0) {
integer /= radix;
buffer[--integer_cursor] = '0';
}
do {
double remainder = modulo(integer, radix);
buffer[--integer_cursor] = chars[static_cast<int>(remainder)];
integer = (integer - remainder) / radix;
} while (integer > 0);
// Add sign and terminate string.
if (negative) buffer[--integer_cursor] = '-';
buffer[fraction_cursor++] = '\0';
DCHECK_LT(fraction_cursor, kBufferSize);
DCHECK_LE(0, integer_cursor);
// Allocate new string as return value.
char* result = NewArray<char>(fraction_cursor - integer_cursor);
memcpy(result, buffer + integer_cursor, fraction_cursor - integer_cursor);
return result;
}
// ES6 18.2.4 parseFloat(string)
double StringToDouble(UnicodeCache* unicode_cache, Handle<String> string,
int flags, double empty_string_val) {
Handle<String> flattened = String::Flatten(string);
{
DisallowHeapAllocation no_gc;
String::FlatContent flat = flattened->GetFlatContent();
DCHECK(flat.IsFlat());
if (flat.IsOneByte()) {
return StringToDouble(unicode_cache, flat.ToOneByteVector(), flags,
empty_string_val);
} else {
return StringToDouble(unicode_cache, flat.ToUC16Vector(), flags,
empty_string_val);
}
}
}
bool IsSpecialIndex(UnicodeCache* unicode_cache, String* string) {
// Max length of canonical double: -X.XXXXXXXXXXXXXXXXX-eXXX
const int kBufferSize = 24;
const int length = string->length();
if (length == 0 || length > kBufferSize) return false;
uint16_t buffer[kBufferSize];
String::WriteToFlat(string, buffer, 0, length);
// If the first char is not a digit or a '-' or we can't match 'NaN' or
// '(-)Infinity', bailout immediately.
int offset = 0;
if (!IsDecimalDigit(buffer[0])) {
if (buffer[0] == '-') {
if (length == 1) return false; // Just '-' is bad.
if (!IsDecimalDigit(buffer[1])) {
if (buffer[1] == 'I' && length == 9) {
// Allow matching of '-Infinity' below.
} else {
return false;
}
}
offset++;
} else if (buffer[0] == 'I' && length == 8) {
// Allow matching of 'Infinity' below.
} else if (buffer[0] == 'N' && length == 3) {
// Match NaN.
return buffer[1] == 'a' && buffer[2] == 'N';
} else {
return false;
}
}
// Expected fast path: key is an integer.
static const int kRepresentableIntegerLength = 15; // (-)XXXXXXXXXXXXXXX
if (length - offset <= kRepresentableIntegerLength) {
const int initial_offset = offset;
bool matches = true;
for (; offset < length; offset++) {
matches &= IsDecimalDigit(buffer[offset]);
}
if (matches) {
// Match 0 and -0.
if (buffer[initial_offset] == '0') return initial_offset == length - 1;
return true;
}
}
// Slow path: test DoubleToString(StringToDouble(string)) == string.
Vector<const uint16_t> vector(buffer, length);
double d = StringToDouble(unicode_cache, vector, NO_FLAGS);
if (std::isnan(d)) return false;
// Compute reverse string.
char reverse_buffer[kBufferSize + 1]; // Result will be /0 terminated.
Vector<char> reverse_vector(reverse_buffer, arraysize(reverse_buffer));
const char* reverse_string = DoubleToCString(d, reverse_vector);
for (int i = 0; i < length; ++i) {
if (static_cast<uint16_t>(reverse_string[i]) != buffer[i]) return false;
}
return true;
}
} // namespace internal
} // namespace v8