// 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 #include #include "v8.h" #include "conversions-inl.h" #include "dtoa.h" #include "factory.h" #include "scanner.h" #include "strtod.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 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; } // 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 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 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(*current) - '0'; } else if (radix > 10 && *current >= 'a' && *current < 'a' + radix - 10) { digit = static_cast(*current) - 'a' + 10; } else if (radix > 10 && *current >= 'A' && *current < 'A' + radix - 10) { digit = static_cast(*current) - 'A' + 10; } else { if (allow_trailing_junk || !AdvanceToNonspace(¤t, end)) { break; } else { return JUNK_STRING_VALUE; } } number = number * radix + digit; int overflow = static_cast(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(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(¤t, 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(static_cast(number)) == number); if (exponent == 0) { if (sign) { if (number == 0) return -0.0; number = -number; } return static_cast(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(sign ? -number : number) * pow(2.0, exponent); } template 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(¤t, end)) return empty_string_val; bool sign = false; bool leading_zero = false; if (*current == '+') { // Ignore leading sign; skip following spaces. ++current; if (!AdvanceToNonspace(¤t, end)) return JUNK_STRING_VALUE; } else if (*current == '-') { ++current; if (!AdvanceToNonspace(¤t, 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(*current); } ++current; if (current == end) break; } if (!allow_trailing_junk && AdvanceToNonspace(¤t, end)) { return JUNK_STRING_VALUE; } ASSERT(buffer_pos < kBufferSize); buffer[buffer_pos] = '\0'; Vector buffer_vector(buffer, buffer_pos); return sign ? -Strtod(buffer_vector, 0) : Strtod(buffer_vector, 0); } // 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(¤t, 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 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(¤t, end)) return empty_string_val; const bool allow_trailing_junk = (flags & ALLOW_TRAILING_JUNK) != 0; // The longest form of simplified number is: "-'.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(¤t, end)) return JUNK_STRING_VALUE; } else if (*current == '-') { ++current; if (!AdvanceToNonspace(¤t, end)) return JUNK_STRING_VALUE; sign = true; } static const char kInfinitySymbol[] = "Infinity"; if (*current == kInfinitySymbol[0]) { if (!SubStringEquals(¤t, end, kInfinitySymbol)) { return JUNK_STRING_VALUE; } if (!allow_trailing_junk && AdvanceToNonspace(¤t, end)) { return JUNK_STRING_VALUE; } ASSERT(buffer_pos == 0); return sign ? -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". } 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(*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 == '.') { if (octal && !allow_trailing_junk) return JUNK_STRING_VALUE; if (octal) goto parsing_done; ++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. } } // We don't emit a '.', but adjust the exponent instead. fractional_part = true; // There is a fractional part. while (*current >= '0' && *current <= '9') { if (significant_digits < kMaxSignificantDigits) { ASSERT(buffer_pos < kBufferSize); buffer[buffer_pos++] = static_cast(*current); significant_digits++; exponent--; } 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(*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(¤t, end)) { return JUNK_STRING_VALUE; } parsing_done: exponent += insignificant_digits; if (octal) { return InternalStringToIntDouble<3>(buffer, buffer + buffer_pos, sign, allow_trailing_junk); } if (nonzero_digit_dropped) { buffer[buffer_pos++] = '1'; exponent--; } ASSERT(buffer_pos < kBufferSize); buffer[buffer_pos] = '\0'; double converted = Strtod(Vector(buffer, buffer_pos), exponent); return sign? -converted: converted; } 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); } double StringToDouble(Vector str, int flags, double empty_string_val) { const char* end = str.start() + str.length(); return InternalStringToDouble(str.start(), 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 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(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 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 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(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) { const int kMaxDigitsAfterPoint = 20; // f might be -1 to signal that f was undefined in JavaScript. ASSERT(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; char* decimal_rep = NULL; bool used_gay_dtoa = false; // 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). ASSERT(kBase10MaximalLength <= kMaxDigitsAfterPoint + 1); char v8_dtoa_buffer[kV8DtoaBufferCapacity]; int decimal_rep_length; if (f == -1) { if (DoubleToAscii(value, DTOA_SHORTEST, 0, Vector(v8_dtoa_buffer, kV8DtoaBufferCapacity), &sign, &decimal_rep_length, &decimal_point)) { f = decimal_rep_length - 1; decimal_rep = v8_dtoa_buffer; } else { decimal_rep = dtoa(value, 0, 0, &decimal_point, &sign, NULL); decimal_rep_length = StrLength(decimal_rep); f = decimal_rep_length - 1; used_gay_dtoa = true; } } else { if (DoubleToAscii(value, DTOA_PRECISION, f + 1, Vector(v8_dtoa_buffer, kV8DtoaBufferCapacity), &sign, &decimal_rep_length, &decimal_point)) { decimal_rep = v8_dtoa_buffer; } else { decimal_rep = dtoa(value, 2, f + 1, &decimal_point, &sign, NULL); decimal_rep_length = StrLength(decimal_rep); used_gay_dtoa = true; } } ASSERT(decimal_rep_length > 0); ASSERT(decimal_rep_length <= f + 1); int exponent = decimal_point - 1; char* result = CreateExponentialRepresentation(decimal_rep, exponent, negative, f+1); if (used_gay_dtoa) { freedtoa(decimal_rep); } return result; } char* DoubleToPrecisionCString(double value, int p) { const int kMinimalDigits = 1; const int kMaximalDigits = 21; ASSERT(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; char* decimal_rep = NULL; bool used_gay_dtoa = false; // Add one for the terminating null character. const int kV8DtoaBufferCapacity = kMaximalDigits + 1; char v8_dtoa_buffer[kV8DtoaBufferCapacity]; int decimal_rep_length; if (DoubleToAscii(value, DTOA_PRECISION, p, Vector(v8_dtoa_buffer, kV8DtoaBufferCapacity), &sign, &decimal_rep_length, &decimal_point)) { decimal_rep = v8_dtoa_buffer; } else { decimal_rep = dtoa(value, 2, p, &decimal_point, &sign, NULL); decimal_rep_length = StrLength(decimal_rep); used_gay_dtoa = true; } 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(); } if (used_gay_dtoa) { 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(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(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