3.0.0

Breaking changes

• The default behavior for scanning integers is now d (decimal) instead of i (detect base from prefix).

// v3
auto result = scn::scan<int>("077", "{}");
// result->value() == 77
result = scn::scan<int>("078", "{}");
// result->value() == 78

// v2
auto result = scn::scan<int>("077", "{}");
// result->value() == 63
result = scn::scan<int>("078", "{}");
// result->value() == 7
// result->range() == "8"
// (Because of the '0' prefix, an octal number is expected,
//  and '8' is not a valid octal digit, so reading is stopped)

• A large part of the bundled <ranges>-implementation is removed.
  Only the parts strictly needed for the library are included.
  • The library no longer uses a stdlib provided <ranges>, even if available.
  • This cut down compile times massively for library consumers
  • You now may need to specialize scn::ranges::enable_borrowed_range for your own range types,
    even if you've already specialized std::ranges::enable_borrowed_range.
    Specializations of std::basic_string_view are already borrowed out of the box.

// std::span is a borrowed_range,
// but scnlib doesn't know about it
auto result = scn::scan<...>(std::span{...}, ...);
// decltype(result->range()) is scn::ranges::dangling

namespace scn::ranges {
template <typename T, size_t E>
inline constexpr bool enable_borrowed_range<std::span<T, E>> = true;
}

auto result = scn::scan<...>(std::span{...}, ...);
// decltype(result->range()) is a scn::ranges::subrange<const T*>

• scn::span is removed
• scan_arg_store and borrowed_subrange_with_sentinel are removed from the public interface
• scan_arg_store is changed to be non-copyable and non-movable, for correctness reasons
  (it holds references to itself, copying and moving would be needlessly expensive)
• The interface of make_scan_result is changed to take a tuple instead of the now unmovable scan_arg_store.

// v3
auto args = make_scan_args<scan_context, Args...>();
auto result = vscan(source, format, args);
return make_scan_result(std::move(result), std::move(args.args()));

// v2
auto args = make_scan_args<scan_context, Args...>();
auto result = vscan(source, format, args);
return make_scan_result(std::move(result), std::move(args));

• The meaning of the "width" field in format specifiers is changed to mean the minimum field width
  (like in std::format), instead of the maximum (sort of like in scanf)

// v3
auto result = std::scan<int>("123", "{:2}");
// result->value() == 123
// result->range() == ""

// v2
auto result = std::scan<int>("123", "{:2}");
// result->value() == 12
// result->range() == "3"

Features

• The "precision" field is added as a format specifier,
  which specifies the maximum fields width to scan (like in std::format)

// Scan up to 2 width units
auto result = scn::scan<int>("123", "{:.2}");
// result->value() == 12
// result->range() == "3"

• Support for field fill and alignment is added.
  This interacts well with the new width and precision fields

// Read an integer, aligned to the right ('>'), with asterisks ('*')
auto result = std::scan<int>("***42", "{:*>}");
// result->value() == 42
// result->range() == ""

// Read an integer, aligned to the left ('<'), with whitespace (default),
// with a maximum total width of 3
auto result = std::scan<int>("42  ", "{:<.3}");
// result->value() == 42
// result->range() == " "

• In general, there seems to be a ~10% to 20% improvement in run-time performance.

Changes

• The dependency on simdutf is removed. The library now has no external dependencies to compiled libraries
  (FastFloat, an internal dependency, is a header-only library)
• The number of source files is dramatically decreased: there are now just the public headers,
  a private implementation header, and a private implementation source file. This cuts down the time needed to
  compile the library, and any user code including it to a half (yes, really!)

Fixes

• Fix skipping of multiple characters of whitespace in the format string (reported in #116, thanks @Jonathan-Greve (Jonathan Bjørn Greve))

Full Changelog: v2.0.3...v3.0.0

2.0.3

Fixes:

• Fix documentation: default format type specifier for integers is i, not d:
  when not explicitly specified by a format specifier, the base of an integer is determined based on its prefix:
  0x... is hexadecimal, 0... or 0o... is octal, 0b... is binary, and everything else is decimal.
• Fix a compilation error which would occur when scanning more than 11 arguments with scn::scan.
• Small CMake adjustments to better support use as a subproject (#113, thanks @frankmiller (Frank Miller))
• Fix misplaced include of GNUInstallDirs in CMake (#111, thanks @WangWeiLin-MV)
• Allow for externally installed versions for GTest and Google Benchmark (#112, thanks @xvitaly (Vitaly))
• Adjust the definition of SCN_COMPILER to fix usage with a recent Clang using modules (#109, thanks @Delta-dev-99 (Armando Martin))
• Allow for more versions of dependencies (simdutf, fast_float)
• Fix C++23 build failure caused by missing inclusion of <utility> for std::unreachable

Full Changelog: v2.0.2...v2.0.3

2.0.2

Minor fixes:

• Fix segfault when runtime-parsing {:[^ as a format string.
• Fix compilation of scan_buffer.cpp on some MSVC versions.
• Remove stray test/ folder

Full Changelog: v2.0.1...v2.0.2

2.0.1

Minor bugfixes

• Fix detection of support for std::regex_constants::multiline (#98, thanks @jiayuehua (Jia Yue Hua))
• Fix builds of float_reader on Android SDK < v28 (#99, thanks @jiayuehua (Jia Yue Hua))
• Fix typo in README example (#100, thanks @ednolan (Eddie Nolan))

Full Changelog: v2.0.0...v2.0.1

2.0.0

Major overhaul, both internally and in terms of the library interface. The library is rewritten in its entirety. See the documentation at https://scnlib.dev/, namely the Migration guide for more details.

The changes below are relative to v1. See CHANGELOG.md for changes relative to v2.0.0-beta.

Major changes include:

• C++17 is required.
• Several names are changed to include the scan_ prefix.
• scn::scan returns the scanned values by value. Output parameters are no longer used.
• scn::scan now accepts all forward_ranges (v1: bidirectional_range + default- and move constructible).
• scn::scan returns a view (subrange) into its input, and never takes ownership.
• Scope is more focused: list operations, ignore, getline, and file have been removed.
• Support for regular expressions.
• Better Unicode support.
• Performance improvements.
• Completely reworked internals.

Full Changelog: v2.0.0-beta...v2.0.0

1.1.3

Expected to be the last release in the v1-branch.
Development efforts are now fully directed towards v2.

Features

• Allow disabling support for individual types with SCN_DISABLE_TYPE_* (#70, thanks @cjvaughter (CJ Vaughter))
  • Also, allow for disabling the fallbacks to std::from_chars and std::strtod when scanning floats
  • This provides possible binary size reductions, and allows better use in e.g. embedded platforms
• Allow disabling runtime localization with SCN_DISABLE_LOCALE (#71, thanks @cjvaughter (CJ Vaughter))
• Parse leading + signs in floats (reported in #77)

Fixes

• Fix scn::wrap(std::string_view&&) being ambiguous on gcc (reported in #83)
• Fix compiler error in scn::basic_string_view<CharT>::substr (reported in #86)
• Fix memory safety issues found with ASan and UBsan in
  small_vector, detail::utf16::validate_next, and detail::get_buffer.
• Add COMPONENT to CMake install targets (#80, thanks @pawelwod)
• Fix calculation of SCN_MSVC from _MSC_FULL_VER (#62, thanks @matbech (Mathias Berchtold))
• Fix MSVC C4146 warning in integer_scanner (#64, thanks @matbech (Mathias Berchtold))
• Use if constexpr and std::unreachable if available (#61, #78, thanks @matbech (Mathias Berchtold))
• Improve error messages given from the float parser

2.0.0-beta

Major overhaul, both internally and in terms of the library interface. The library is rewritten in its entirety. See the documentation (note the new URL: https://v2.scnlib.dev), namely the Migration guide for more details.

This is a beta pre-release. There may still be some bugs. Changes before v2.0.0 proper are possible, but aren't probably going to be major.

Major changes include:

• C++17 is required.
• Several names are changed to include the scan_ prefix.
• scn::scan returns the scanned values by value. Output parameters are no longer used.
• scn::scan now accepts all forward_ranges (v1: bidirectional_range + default- and move constructible).
• scn::scan returns a view (subrange) into its input, and never takes ownership.
• Scope is more focused: list operations, ignore, getline, and file have been removed.
• Performance improvements
• Completely reworked internals

1.1.2

• Change SCN_VERSION to report the correct version number: 1.1.0 -> 1.1.2 (#57)

1.1.1

• Fix issue with values being skipped when using files and file.sync() (#56)
  • Every call to file.sync() needs to be accompanied by a call to reset_begin_iterator() to the result object
  • This is a temporary fix, permanent fix coming in v2.0.0

int i;
auto ret = scn::scan(scn::cstdin(), "{}", i);
scn::cstdin().sync();
ret.range().reset_begin_iterator();

// Not necessary with input and prompt
ret = scn::input("{}", i);

1.1

• Add support for scanning 8-bit integers ((un)signed char, (u)int8_t),
  and characters (char, wchar_t) as integers

int8_t i1, i2;
char c1, c2;
auto ret = scn::scan("1 2 3 4", "{} {:c} {} {:i}", i1, i2, i3, i4);
// ret == true
// i1 == 1
// i2 == '2'
// c1 == '3'
// c2 == 4

• Fix usage of external fast_float in CMake (#53, thanks @xvitaly (Vitaly Zaitsev))
• Fix tests on big endian architectures (#54)
• Fix alignment issues with small_vector on 32-bit architectures

Full Changelog: v1.0...v1.1