double-conversion-string-to-double.h

// © 2018 and later: Unicode, Inc. and others.

// License & terms of use: http://www.unicode.org/copyright.html

//

// From the double-conversion library. Original license:

//

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// ICU PATCH: ifdef around UCONFIG_NO_FORMATTING

#include "unicode/utypes.h"

#if !UCONFIG_NO_FORMATTING

#ifndef DOUBLE_CONVERSION_STRING_TO_DOUBLE_H_

#define DOUBLE_CONVERSION_STRING_TO_DOUBLE_H_

// ICU PATCH: Customize header file paths for ICU.

#include "double-conversion-utils.h"

// ICU PATCH: Wrap in ICU namespace

U_NAMESPACE_BEGIN

namespace double_conversion {

class StringToDoubleConverter {

 public:

  // Enumeration for allowing octals and ignoring junk when converting

  // strings to numbers.

  enum Flags {

    NO_FLAGS = 0,

    ALLOW_HEX = 1,

    ALLOW_OCTALS = 2,

    ALLOW_TRAILING_JUNK = 4,

    ALLOW_LEADING_SPACES = 8,

    ALLOW_TRAILING_SPACES = 16,

    ALLOW_SPACES_AFTER_SIGN = 32,

    ALLOW_CASE_INSENSITIVITY = 64,

    ALLOW_CASE_INSENSIBILITY = 64,  // Deprecated

    ALLOW_HEX_FLOATS = 128,

};

  static const uc16 kNoSeparator = '\0';

  // Flags should be a bit-or combination of the possible Flags-enum.

  //  - NO_FLAGS: no special flags.

  //  - ALLOW_HEX: recognizes the prefix "0x". Hex numbers may only be integers.

  //      Ex: StringToDouble("0x1234") -> 4660.0

  //          In StringToDouble("0x1234.56") the characters ".56" are trailing

  //          junk. The result of the call is hence dependent on

  //          the ALLOW_TRAILING_JUNK flag and/or the junk value.

  //      With this flag "0x" is a junk-string. Even with ALLOW_TRAILING_JUNK,

  //      the string will not be parsed as "0" followed by junk.

//

  //  - ALLOW_OCTALS: recognizes the prefix "0" for octals:

  //      If a sequence of octal digits starts with '0', then the number is

  //      read as octal integer. Octal numbers may only be integers.

  //      Ex: StringToDouble("01234") -> 668.0

  //          StringToDouble("012349") -> 12349.0  // Not a sequence of octal

  //                                               // digits.

  //          In StringToDouble("01234.56") the characters ".56" are trailing

  //          junk. The result of the call is hence dependent on

  //          the ALLOW_TRAILING_JUNK flag and/or the junk value.

  //          In StringToDouble("01234e56") the characters "e56" are trailing

  //          junk, too.

  //  - ALLOW_TRAILING_JUNK: ignore trailing characters that are not part of

  //      a double literal.

  //  - ALLOW_LEADING_SPACES: skip over leading whitespace, including spaces,

  //                          new-lines, and tabs.

  //  - ALLOW_TRAILING_SPACES: ignore trailing whitespace.

  //  - ALLOW_SPACES_AFTER_SIGN: ignore whitespace after the sign.

  //       Ex: StringToDouble("-   123.2") -> -123.2.

  //           StringToDouble("+   123.2") -> 123.2

  //  - ALLOW_CASE_INSENSITIVITY: ignore case of characters for special values:

  //      infinity and nan.

  //  - ALLOW_HEX_FLOATS: allows hexadecimal float literals.

  //      This *must* start with "0x" and separate the exponent with "p".

  //      Examples: 0x1.2p3 == 9.0

  //                0x10.1p0 == 16.0625

  //      ALLOW_HEX and ALLOW_HEX_FLOATS are indented.

//

  // empty_string_value is returned when an empty string is given as input.

  // If ALLOW_LEADING_SPACES or ALLOW_TRAILING_SPACES are set, then a string

  // containing only spaces is converted to the 'empty_string_value', too.

//

  // junk_string_value is returned when

  //  a) ALLOW_TRAILING_JUNK is not set, and a junk character (a character not

  //     part of a double-literal) is found.

  //  b) ALLOW_TRAILING_JUNK is set, but the string does not start with a

  //     double literal.

//

  // infinity_symbol and nan_symbol are strings that are used to detect

  // inputs that represent infinity and NaN. They can be null, in which case

  // they are ignored.

  // The conversion routine first reads any possible signs. Then it compares the

  // following character of the input-string with the first character of

  // the infinity, and nan-symbol. If either matches, the function assumes, that

  // a match has been found, and expects the following input characters to match

  // the remaining characters of the special-value symbol.

  // This means that the following restrictions apply to special-value symbols:

  //  - they must not start with signs ('+', or '-'),

  //  - they must not have the same first character.

  //  - they must not start with digits.

//

  // If the separator character is not kNoSeparator, then that specific

  // character is ignored when in between two valid digits of the significant.

  // It is not allowed to appear in the exponent.

  // It is not allowed to lead or trail the number.

  // It is not allowed to appear twice next to each other.

//

  // Examples:

  //  flags = ALLOW_HEX | ALLOW_TRAILING_JUNK,

  //  empty_string_value = 0.0,

  //  junk_string_value = NaN,

  //  infinity_symbol = "infinity",

  //  nan_symbol = "nan":

  //    StringToDouble("0x1234") -> 4660.0.

  //    StringToDouble("0x1234K") -> 4660.0.

  //    StringToDouble("") -> 0.0  // empty_string_value.

  //    StringToDouble(" ") -> NaN  // junk_string_value.

  //    StringToDouble(" 1") -> NaN  // junk_string_value.

  //    StringToDouble("0x") -> NaN  // junk_string_value.

  //    StringToDouble("-123.45") -> -123.45.

  //    StringToDouble("--123.45") -> NaN  // junk_string_value.

  //    StringToDouble("123e45") -> 123e45.

  //    StringToDouble("123E45") -> 123e45.

  //    StringToDouble("123e+45") -> 123e45.

  //    StringToDouble("123E-45") -> 123e-45.

  //    StringToDouble("123e") -> 123.0  // trailing junk ignored.

  //    StringToDouble("123e-") -> 123.0  // trailing junk ignored.

  //    StringToDouble("+NaN") -> NaN  // NaN string literal.

  //    StringToDouble("-infinity") -> -inf.  // infinity literal.

  //    StringToDouble("Infinity") -> NaN  // junk_string_value.

//

  //  flags = ALLOW_OCTAL | ALLOW_LEADING_SPACES,

  //  empty_string_value = 0.0,

  //  junk_string_value = NaN,

  //  infinity_symbol = nullptr,

  //  nan_symbol = nullptr:

  //    StringToDouble("0x1234") -> NaN  // junk_string_value.

  //    StringToDouble("01234") -> 668.0.

  //    StringToDouble("") -> 0.0  // empty_string_value.

  //    StringToDouble(" ") -> 0.0  // empty_string_value.

  //    StringToDouble(" 1") -> 1.0

  //    StringToDouble("0x") -> NaN  // junk_string_value.

  //    StringToDouble("0123e45") -> NaN  // junk_string_value.

  //    StringToDouble("01239E45") -> 1239e45.

  //    StringToDouble("-infinity") -> NaN  // junk_string_value.

  //    StringToDouble("NaN") -> NaN  // junk_string_value.

//

  //  flags = NO_FLAGS,

  //  separator = ' ':

  //    StringToDouble("1 2 3 4") -> 1234.0

  //    StringToDouble("1  2") -> NaN // junk_string_value

  //    StringToDouble("1 000 000.0") -> 1000000.0

  //    StringToDouble("1.000 000") -> 1.0

  //    StringToDouble("1.0e1 000") -> NaN // junk_string_value

  StringToDoubleConverter(int flags,

                          double empty_string_value,

                          double junk_string_value,

                          const char* infinity_symbol,

                          const char* nan_symbol,

                          uc16 separator = kNoSeparator)

      : flags_(flags),

        empty_string_value_(empty_string_value),

        junk_string_value_(junk_string_value),

        infinity_symbol_(infinity_symbol),

        nan_symbol_(nan_symbol),

        separator_(separator) {

  // Performs the conversion.

  // The output parameter 'processed_characters_count' is set to the number

  // of characters that have been processed to read the number.

  // Spaces than are processed with ALLOW_{LEADING|TRAILING}_SPACES are included

  // in the 'processed_characters_count'. Trailing junk is never included.

  double StringToDouble(const char* buffer,

                        int length,

                        int* processed_characters_count) const;

  // Same as StringToDouble above but for 16 bit characters.

  double StringToDouble(const uc16* buffer,

                        int length,

                        int* processed_characters_count) const;

  // Same as StringToDouble but reads a float.

  // Note that this is not equivalent to static_cast<float>(StringToDouble(...))

  // due to potential double-rounding.

  float StringToFloat(const char* buffer,

                      int length,

                      int* processed_characters_count) const;

  // Same as StringToFloat above but for 16 bit characters.

  float StringToFloat(const uc16* buffer,

                      int length,

                      int* processed_characters_count) const;

  // Same as StringToDouble for T = double, and StringToFloat for T = float.

  template <typename T>

  T StringTo(const char* buffer,

             int length,

             int* processed_characters_count) const;

  // Same as StringTo above but for 16 bit characters.

  template <typename T>

  T StringTo(const uc16* buffer,

             int length,

             int* processed_characters_count) const;

 private:

  const int flags_;

  const double empty_string_value_;

  const double junk_string_value_;

  const char* const infinity_symbol_;

  const char* const nan_symbol_;

  const uc16 separator_;

  template <class Iterator>

  double StringToIeee(Iterator start_pointer,

                      int length,

                      bool read_as_double,

                      int* processed_characters_count) const;

  DOUBLE_CONVERSION_DISALLOW_IMPLICIT_CONSTRUCTORS(StringToDoubleConverter);

};

}  // namespace double_conversion

// ICU PATCH: Close ICU namespace

U_NAMESPACE_END

#endif  // DOUBLE_CONVERSION_STRING_TO_DOUBLE_H_

#endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING

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