| // Copyright 2012 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. |
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| |
| #ifndef DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ |
| #define DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ |
| |
| #include <wtf/dtoa/utils.h> |
| |
| namespace WTF { |
| namespace double_conversion { |
| |
| class DoubleToStringConverter { |
| public: |
| // When calling ToFixed with a double > 10^kMaxFixedDigitsBeforePoint |
| // or a requested_digits parameter > kMaxFixedDigitsAfterPoint then the |
| // function returns false. |
| static const int kMaxFixedDigitsBeforePoint = 21; |
| static const int kMaxFixedDigitsAfterPoint = 100; |
| |
| // When calling ToExponential with a requested_digits |
| // parameter > kMaxExponentialDigits then the function returns false. |
| static const int kMaxExponentialDigits = 100; |
| |
| // When calling ToPrecision with a requested_digits |
| // parameter < kMinPrecisionDigits or requested_digits > kMaxPrecisionDigits |
| // then the function returns false. |
| static const int kMinPrecisionDigits = 1; |
| static const int kMaxPrecisionDigits = 100; |
| |
| enum Flags { |
| NO_FLAGS = 0, |
| EMIT_POSITIVE_EXPONENT_SIGN = 1, |
| EMIT_TRAILING_DECIMAL_POINT = 2, |
| EMIT_TRAILING_ZERO_AFTER_POINT = 4, |
| UNIQUE_ZERO = 8 |
| }; |
| |
| // Flags should be a bit-or combination of the possible Flags-enum. |
| // - NO_FLAGS: no special flags. |
| // - EMIT_POSITIVE_EXPONENT_SIGN: when the number is converted into exponent |
| // form, emits a '+' for positive exponents. Example: 1.2e+2. |
| // - EMIT_TRAILING_DECIMAL_POINT: when the input number is an integer and is |
| // converted into decimal format then a trailing decimal point is appended. |
| // Example: 2345.0 is converted to "2345.". |
| // - EMIT_TRAILING_ZERO_AFTER_POINT: in addition to a trailing decimal point |
| // emits a trailing '0'-character. This flag requires the |
| // EXMIT_TRAILING_DECIMAL_POINT flag. |
| // Example: 2345.0 is converted to "2345.0". |
| // - UNIQUE_ZERO: "-0.0" is converted to "0.0". |
| // |
| // Infinity symbol and nan_symbol provide the string representation for these |
| // special values. If the string is NULL and the special value is encountered |
| // then the conversion functions return false. |
| // |
| // The exponent_character is used in exponential representations. It is |
| // usually 'e' or 'E'. |
| // |
| // When converting to the shortest representation the converter will |
| // represent input numbers in decimal format if they are in the interval |
| // [10^decimal_in_shortest_low; 10^decimal_in_shortest_high[ |
| // (lower boundary included, greater boundary excluded). |
| // Example: with decimal_in_shortest_low = -6 and |
| // decimal_in_shortest_high = 21: |
| // ToShortest(0.000001) -> "0.000001" |
| // ToShortest(0.0000001) -> "1e-7" |
| // ToShortest(111111111111111111111.0) -> "111111111111111110000" |
| // ToShortest(100000000000000000000.0) -> "100000000000000000000" |
| // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21" |
| // |
| // When converting to precision mode the converter may add |
| // max_leading_padding_zeroes before returning the number in exponential |
| // format. |
| // Example with max_leading_padding_zeroes_in_precision_mode = 6. |
| // ToPrecision(0.0000012345, 2) -> "0.0000012" |
| // ToPrecision(0.00000012345, 2) -> "1.2e-7" |
| // Similarily the converter may add up to |
| // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid |
| // returning an exponential representation. A zero added by the |
| // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit. |
| // Examples for max_trailing_padding_zeroes_in_precision_mode = 1: |
| // ToPrecision(230.0, 2) -> "230" |
| // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT. |
| // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT. |
| DoubleToStringConverter(int flags, |
| const char* infinity_symbol, |
| const char* nan_symbol, |
| char exponent_character, |
| int decimal_in_shortest_low, |
| int decimal_in_shortest_high, |
| int max_leading_padding_zeroes_in_precision_mode, |
| int max_trailing_padding_zeroes_in_precision_mode) |
| : flags_(flags), |
| infinity_symbol_(infinity_symbol), |
| nan_symbol_(nan_symbol), |
| exponent_character_(exponent_character), |
| decimal_in_shortest_low_(decimal_in_shortest_low), |
| decimal_in_shortest_high_(decimal_in_shortest_high), |
| max_leading_padding_zeroes_in_precision_mode_( |
| max_leading_padding_zeroes_in_precision_mode), |
| max_trailing_padding_zeroes_in_precision_mode_( |
| max_trailing_padding_zeroes_in_precision_mode) { |
| // When 'trailing zero after the point' is set, then 'trailing point' |
| // must be set too. |
| ASSERT(((flags & EMIT_TRAILING_DECIMAL_POINT) != 0) || |
| !((flags & EMIT_TRAILING_ZERO_AFTER_POINT) != 0)); |
| } |
| |
| // Returns a converter following the EcmaScript specification. |
| WTF_EXPORT_PRIVATE static const DoubleToStringConverter& EcmaScriptConverter(); |
| |
| // Computes the shortest string of digits that correctly represent the input |
| // number. Depending on decimal_in_shortest_low and decimal_in_shortest_high |
| // (see constructor) it then either returns a decimal representation, or an |
| // exponential representation. |
| // Example with decimal_in_shortest_low = -6, |
| // decimal_in_shortest_high = 21, |
| // EMIT_POSITIVE_EXPONENT_SIGN activated, and |
| // EMIT_TRAILING_DECIMAL_POINT deactived: |
| // ToShortest(0.000001) -> "0.000001" |
| // ToShortest(0.0000001) -> "1e-7" |
| // ToShortest(111111111111111111111.0) -> "111111111111111110000" |
| // ToShortest(100000000000000000000.0) -> "100000000000000000000" |
| // ToShortest(1111111111111111111111.0) -> "1.1111111111111111e+21" |
| // |
| // Note: the conversion may round the output if the returned string |
| // is accurate enough to uniquely identify the input-number. |
| // For example the most precise representation of the double 9e59 equals |
| // "899999999999999918767229449717619953810131273674690656206848", but |
| // the converter will return the shorter (but still correct) "9e59". |
| // |
| // Returns true if the conversion succeeds. The conversion always succeeds |
| // except when the input value is special and no infinity_symbol or |
| // nan_symbol has been given to the constructor. |
| bool ToShortest(double value, StringBuilder* result_builder) const { |
| return ToShortestIeeeNumber(value, result_builder, SHORTEST); |
| } |
| |
| // Same as ToShortest, but for single-precision floats. |
| bool ToShortestSingle(float value, StringBuilder* result_builder) const { |
| return ToShortestIeeeNumber(value, result_builder, SHORTEST_SINGLE); |
| } |
| |
| |
| // Computes a decimal representation with a fixed number of digits after the |
| // decimal point. The last emitted digit is rounded. |
| // |
| // Examples: |
| // ToFixed(3.12, 1) -> "3.1" |
| // ToFixed(3.1415, 3) -> "3.142" |
| // ToFixed(1234.56789, 4) -> "1234.5679" |
| // ToFixed(1.23, 5) -> "1.23000" |
| // ToFixed(0.1, 4) -> "0.1000" |
| // ToFixed(1e30, 2) -> "1000000000000000019884624838656.00" |
| // ToFixed(0.1, 30) -> "0.100000000000000005551115123126" |
| // ToFixed(0.1, 17) -> "0.10000000000000001" |
| // |
| // If requested_digits equals 0, then the tail of the result depends on |
| // the EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT. |
| // Examples, for requested_digits == 0, |
| // let EMIT_TRAILING_DECIMAL_POINT and EMIT_TRAILING_ZERO_AFTER_POINT be |
| // - false and false: then 123.45 -> 123 |
| // 0.678 -> 1 |
| // - true and false: then 123.45 -> 123. |
| // 0.678 -> 1. |
| // - true and true: then 123.45 -> 123.0 |
| // 0.678 -> 1.0 |
| // |
| // Returns true if the conversion succeeds. The conversion always succeeds |
| // except for the following cases: |
| // - the input value is special and no infinity_symbol or nan_symbol has |
| // been provided to the constructor, |
| // - 'value' > 10^kMaxFixedDigitsBeforePoint, or |
| // - 'requested_digits' > kMaxFixedDigitsAfterPoint. |
| // The last two conditions imply that the result will never contain more than |
| // 1 + kMaxFixedDigitsBeforePoint + 1 + kMaxFixedDigitsAfterPoint characters |
| // (one additional character for the sign, and one for the decimal point). |
| bool ToFixed(double value, |
| int requested_digits, |
| StringBuilder* result_builder) const; |
| |
| // Computes a representation in exponential format with requested_digits |
| // after the decimal point. The last emitted digit is rounded. |
| // If requested_digits equals -1, then the shortest exponential representation |
| // is computed. |
| // |
| // Examples with EMIT_POSITIVE_EXPONENT_SIGN deactivated, and |
| // exponent_character set to 'e'. |
| // ToExponential(3.12, 1) -> "3.1e0" |
| // ToExponential(5.0, 3) -> "5.000e0" |
| // ToExponential(0.001, 2) -> "1.00e-3" |
| // ToExponential(3.1415, -1) -> "3.1415e0" |
| // ToExponential(3.1415, 4) -> "3.1415e0" |
| // ToExponential(3.1415, 3) -> "3.142e0" |
| // ToExponential(123456789000000, 3) -> "1.235e14" |
| // ToExponential(1000000000000000019884624838656.0, -1) -> "1e30" |
| // ToExponential(1000000000000000019884624838656.0, 32) -> |
| // "1.00000000000000001988462483865600e30" |
| // ToExponential(1234, 0) -> "1e3" |
| // |
| // Returns true if the conversion succeeds. The conversion always succeeds |
| // except for the following cases: |
| // - the input value is special and no infinity_symbol or nan_symbol has |
| // been provided to the constructor, |
| // - 'requested_digits' > kMaxExponentialDigits. |
| // The last condition implies that the result will never contain more than |
| // kMaxExponentialDigits + 8 characters (the sign, the digit before the |
| // decimal point, the decimal point, the exponent character, the |
| // exponent's sign, and at most 3 exponent digits). |
| WTF_EXPORT_PRIVATE bool ToExponential(double value, |
| int requested_digits, |
| StringBuilder* result_builder) const; |
| |
| // Computes 'precision' leading digits of the given 'value' and returns them |
| // either in exponential or decimal format, depending on |
| // max_{leading|trailing}_padding_zeroes_in_precision_mode (given to the |
| // constructor). |
| // The last computed digit is rounded. |
| // |
| // Example with max_leading_padding_zeroes_in_precision_mode = 6. |
| // ToPrecision(0.0000012345, 2) -> "0.0000012" |
| // ToPrecision(0.00000012345, 2) -> "1.2e-7" |
| // Similarily the converter may add up to |
| // max_trailing_padding_zeroes_in_precision_mode in precision mode to avoid |
| // returning an exponential representation. A zero added by the |
| // EMIT_TRAILING_ZERO_AFTER_POINT flag is counted for this limit. |
| // Examples for max_trailing_padding_zeroes_in_precision_mode = 1: |
| // ToPrecision(230.0, 2) -> "230" |
| // ToPrecision(230.0, 2) -> "230." with EMIT_TRAILING_DECIMAL_POINT. |
| // ToPrecision(230.0, 2) -> "2.3e2" with EMIT_TRAILING_ZERO_AFTER_POINT. |
| // Examples for max_trailing_padding_zeroes_in_precision_mode = 3, and no |
| // EMIT_TRAILING_ZERO_AFTER_POINT: |
| // ToPrecision(123450.0, 6) -> "123450" |
| // ToPrecision(123450.0, 5) -> "123450" |
| // ToPrecision(123450.0, 4) -> "123500" |
| // ToPrecision(123450.0, 3) -> "123000" |
| // ToPrecision(123450.0, 2) -> "1.2e5" |
| // |
| // Returns true if the conversion succeeds. The conversion always succeeds |
| // except for the following cases: |
| // - the input value is special and no infinity_symbol or nan_symbol has |
| // been provided to the constructor, |
| // - precision < kMinPericisionDigits |
| // - precision > kMaxPrecisionDigits |
| // The last condition implies that the result will never contain more than |
| // kMaxPrecisionDigits + 7 characters (the sign, the decimal point, the |
| // exponent character, the exponent's sign, and at most 3 exponent digits). |
| bool ToPrecision(double value, |
| int precision, |
| StringBuilder* result_builder) const; |
| |
| enum DtoaMode { |
| // Produce the shortest correct representation. |
| // For example the output of 0.299999999999999988897 is (the less accurate |
| // but correct) 0.3. |
| SHORTEST, |
| // Same as SHORTEST, but for single-precision floats. |
| SHORTEST_SINGLE, |
| // Produce a fixed number of digits after the decimal point. |
| // For instance fixed(0.1, 4) becomes 0.1000 |
| // If the input number is big, the output will be big. |
| FIXED, |
| // Fixed number of digits (independent of the decimal point). |
| PRECISION |
| }; |
| |
| // The maximal number of digits that are needed to emit a double in base 10. |
| // A higher precision can be achieved by using more digits, but the shortest |
| // accurate representation of any double will never use more digits than |
| // kBase10MaximalLength. |
| // Note that DoubleToAscii null-terminates its input. So the given buffer |
| // should be at least kBase10MaximalLength + 1 characters long. |
| static const int kBase10MaximalLength = 17; |
| |
| // Converts the given double 'v' to digit characters. 'v' must not be NaN, |
| // +Infinity, or -Infinity. In SHORTEST_SINGLE-mode this restriction also |
| // applies to 'v' after it has been casted to a single-precision float. That |
| // is, in this mode static_cast<float>(v) must not be NaN, +Infinity or |
| // -Infinity. |
| // |
| // The result should be interpreted as buffer * 10^(point-length). |
| // |
| // The digits are written to the buffer in the platform's charset, which is |
| // often UTF-8 (with ASCII-range digits) but may be another charset, such |
| // as EBCDIC. |
| // |
| // The output depends on the given mode: |
| // - SHORTEST: produce the least amount of digits for which the internal |
| // identity requirement is still satisfied. If the digits are printed |
| // (together with the correct exponent) then reading this number will give |
| // 'v' again. The buffer will choose the representation that is closest to |
| // 'v'. If there are two at the same distance, than the one farther away |
| // from 0 is chosen (halfway cases - ending with 5 - are rounded up). |
| // In this mode the 'requested_digits' parameter is ignored. |
| // - SHORTEST_SINGLE: same as SHORTEST but with single-precision. |
| // - FIXED: produces digits necessary to print a given number with |
| // 'requested_digits' digits after the decimal point. The produced digits |
| // might be too short in which case the caller has to fill the remainder |
| // with '0's. |
| // Example: toFixed(0.001, 5) is allowed to return buffer="1", point=-2. |
| // Halfway cases are rounded towards +/-Infinity (away from 0). The call |
| // toFixed(0.15, 2) thus returns buffer="2", point=0. |
| // The returned buffer may contain digits that would be truncated from the |
| // shortest representation of the input. |
| // - PRECISION: produces 'requested_digits' where the first digit is not '0'. |
| // Even though the length of produced digits usually equals |
| // 'requested_digits', the function is allowed to return fewer digits, in |
| // which case the caller has to fill the missing digits with '0's. |
| // Halfway cases are again rounded away from 0. |
| // DoubleToAscii expects the given buffer to be big enough to hold all |
| // digits and a terminating null-character. In SHORTEST-mode it expects a |
| // buffer of at least kBase10MaximalLength + 1. In all other modes the |
| // requested_digits parameter and the padding-zeroes limit the size of the |
| // output. Don't forget the decimal point, the exponent character and the |
| // terminating null-character when computing the maximal output size. |
| // The given length is only used in debug mode to ensure the buffer is big |
| // enough. |
| static void DoubleToAscii(double v, |
| DtoaMode mode, |
| int requested_digits, |
| char* buffer, |
| int buffer_length, |
| bool* sign, |
| int* length, |
| int* point); |
| |
| private: |
| // Implementation for ToShortest and ToShortestSingle. |
| bool ToShortestIeeeNumber(double value, |
| StringBuilder* result_builder, |
| DtoaMode mode) const; |
| |
| // If the value is a special value (NaN or Infinity) constructs the |
| // corresponding string using the configured infinity/nan-symbol. |
| // If either of them is NULL or the value is not special then the |
| // function returns false. |
| bool HandleSpecialValues(double value, StringBuilder* result_builder) const; |
| // Constructs an exponential representation (i.e. 1.234e56). |
| // The given exponent assumes a decimal point after the first decimal digit. |
| void CreateExponentialRepresentation(const char* decimal_digits, |
| int length, |
| int exponent, |
| StringBuilder* result_builder) const; |
| // Creates a decimal representation (i.e 1234.5678). |
| void CreateDecimalRepresentation(const char* decimal_digits, |
| int length, |
| int decimal_point, |
| int digits_after_point, |
| StringBuilder* result_builder) const; |
| |
| const int flags_; |
| const char* const infinity_symbol_; |
| const char* const nan_symbol_; |
| const char exponent_character_; |
| const int decimal_in_shortest_low_; |
| const int decimal_in_shortest_high_; |
| const int max_leading_padding_zeroes_in_precision_mode_; |
| const int max_trailing_padding_zeroes_in_precision_mode_; |
| |
| DC_DISALLOW_IMPLICIT_CONSTRUCTORS(DoubleToStringConverter); |
| }; |
| |
| |
| class StringToDoubleConverter { |
| public: |
| // Performs the conversion. |
| // The output parameter 'processed_characters_count' is set to the number |
| // of characters that have been processed to read the number. |
| WTF_EXPORT_PRIVATE static double StringToDouble(const char* buffer, |
| size_t length, |
| size_t* processed_characters_count); |
| |
| // Same as StringToDouble above but for 16 bit characters. |
| WTF_EXPORT_PRIVATE static double StringToDouble(const uc16* buffer, |
| size_t length, |
| size_t* processed_characters_count); |
| |
| // Same as StringToDouble but reads a float. |
| // Note that this is not equivalent to static_cast<float>(StringToDouble(...)) |
| // due to potential double-rounding. |
| WTF_EXPORT_PRIVATE static float StringToFloat(const char* buffer, |
| size_t length, |
| size_t* processed_characters_count); |
| |
| // Same as StringToFloat above but for 16 bit characters. |
| WTF_EXPORT_PRIVATE static float StringToFloat(const uc16* buffer, |
| size_t length, |
| size_t* processed_characters_count); |
| |
| private: |
| DC_DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter); |
| }; |
| |
| } // namespace double_conversion |
| } // namespace WTF |
| |
| #endif // DOUBLE_CONVERSION_DOUBLE_CONVERSION_H_ |
