Release 0.1.11

Breaking changes

• csubstr::operator==(std::nullptr_t) now strictly checks if the pointer is null and no longer looks at the length (rapidyaml#264):

  -bool csubstr::operator== (std::nullptr_t) const noexcept { return str == nullptr || len == 0; }
  -bool csubstr::operator!= (std::nullptr_t) const noexcept { return str != nullptr || len == 0; }
  +bool csubstr::operator== (std::nullptr_t) const noexcept { return str == nullptr; }
  +bool csubstr::operator!= (std::nullptr_t) const noexcept { return str != nullptr; }

• to_substr(std::string &s) and to_csubstr(std::string const& s) now point at the first element when the string is empty (rapidyaml#264):

  -    return c4::substr(!s.empty() ? &s[0] : nullptr, s.size());
  +    return c4::substr(&s[0], s.size());

  This is OK because an empty std::string is guaranteed to have storage, so calling s[0] is safe.

New features

• charconv.hpp: added xtoa() floating-point overloads accepting precision and format (PR#88):

  size_t xtoa(substr s,  float v, int precision, RealFormat_e formatting=FTOA_FLEX) noexcept;
  size_t xtoa(substr s, double v, int precision, RealFormat_e formatting=FTOA_FLEX) noexcept;

• memory_util.hpp: added ipow() overloads for computing powers with integral exponents (PR#88).
• Add C4_NO_DEBUG_BREAK preprocessor check to disable calls to c4::debug_break() (see rapidyaml#326)
  • The cmake project conditionally enables this macro if the cmake option C4CORE_NO_DEBUG_BREAK is set to ON.

Fixes

• substr, to_chars(), charconv: ensure memcpy() is not called when the length is zero. Doing this is UB and enabled the optimizer to wreak havoc in the branches of calling code. See comments at rapidyaml#264 for an example and fix. See Raymond Chen's blog for an explanation.
• atof() and atod() (PR#88):
  • Always use the fastest implementation available: std::from_chars() if available (C++17 or higher standard, with later compilers), fast_float::from_chars() otherwise. On Visual Studio, fast_float::from_chars() is preferred over std::from_chars().
  • If std::from_chars() is not available and C4CORE_NO_FAST_FLOAT is defined, then the fallback is based on sscanf().
  • Ensure hexadecimal floats are accepted. The current fast_float implementation does not accept hexadecimal floats, so an hexfloat scanner was added.
• Likewise for ftoa() and dtoa(). Prefer the fastest implementation available: std::to_chars()->snprintf().
  • Change the FTOA_* enum values and type to save a function call when converting format. From now on, only the symbols of this enum can be relied on; the values or type will change depending on the selected implementation (std::to_chars() or snprintf()) (PR#91).
• Fix #84: csubstr::compare(char): refactor to avoid false-positive warning from VS2022.
• csubstr methods: add noexcept and annotations C4_PURE and C4_ALWAYS_INLINE
• csubstr: add C4_RESTRICT to incoming string on csubstr::compare()
• csubstr::first_real_span() (PR#89):
  • Refactor to fix number matching rules. Now fully valid for floating point numbers in decimal (eg 0.123/1.23e+01), hexadecimal (eg 0x123.abc/0x1.23abcp+01), binary (eg 0b101.10/0b1.0110p+01) and octal format (eg 0o701.10/0o7.0110p+01) , with or without exponent or power, in lower or upper case.
  • Also, make the number parsing stateful to fix cases where repeated characters occur, (like e.g. 0.1.0 or 1.23e+e10) which are no longer reported as numbers (see biojppm/rapidyaml#291).
• csubstr::first_int_span(), csubstr::first_uint_span(): fix edge cases like e.g. 0xzz which were wrongly reported as numbers.
• Add fully qualified ARM detection macros:
  • __ARM_ARCH_7EM__ (PR#90).
  • __ARM_ARCH_6KZ__ (PR#93).
  • __ARM_ARCH_8A__ (#94).
• Improve linux and unix platform detection: detect both __linux and __linux__ (PR#92).

Thanks

• @mlondono74
• @musicinmybrain
• @pkubaj
• @Gei0r