A C++ Concepts based character encoding and code point enumeration library.
This project is the reference implementation for proposal P0244 for the C++ standard.
This port of Text_view requires a C++17 conforming compiler that implements ISO/IEC technical specification 19217:2015, C++ Extensions for concepts . A port of Text_view that builds with C++11 conforming compilers is available at Text_view for range-v3.
For discussion of this project, please post and/or subscribe to the
text_view@googlegroups.com group hosted at
https://groups.google.com/d/forum/text_view
- Overview
- Current features and limitations
- Requirements
- Build and installation
- Usage
- Supported Encodings
- Terminology
- References
C++11 added support for new character types (N2249) and
Unicode string literals (N2442), but neither C++11,
nor more recent standards have provided means of efficiently and conveniently
enumerating code points in Unicode or legacy encodings. While
it is possible to implement such enumeration using interfaces provided in the
standard <codecvt> library, doing to is awkward, requires that text be
provided as pointers to contiguous memory, and inefficent due to virtual
function call overhead (examples and data required to back up these
assertions).
Text_view provides iterator and range based interfaces for encoding and decoding strings in a variety of character encodings. The interface is intended to support all modern and legacy character encodings, though this library does not yet provide implementations for legacy encodings.
An example usage follows. Note that \u00F8 (LATIN SMALL LETTER O WITH STROKE)
is encoded as UTF-8 using two code units (\xC3\xB8), but
iterator based enumeration sees just the single code point.
using CT = utf8_encoding::character_type;
auto tv = make_text_view<utf8_encoding>(u8"J\u00F8erg is my friend");
auto it = tv.begin();
assert(*it++ == CT{0x004A}); // 'J'
assert(*it++ == CT{0x00F8}); // 'ø'
assert(*it++ == CT{0x0065}); // 'e'The iterators and ranges that Text_view provides are compatible with the
non-modifying sequence utilities provided by the standard C++ <algorithm>
library. This enables use of standard algorithms to search encoded text.
it = std::find(tv.begin(), tv.end(), CT{0x00F8});
assert(it != tv.end());The iterators provided by Text_view also provide access to the underlying code unit sequence.
auto base_it = it.base_range().begin();
assert(*base_it++ == '\xC3');
assert(*base_it++ == '\xB8');
assert(base_it == it.base_range().end());Text_view ranges satisfy the requirements for use in C++11 range-based for statements with the removed same type restriction for the begin and end expressions provided by P0184R0 as adopted for C++17.
for (const auto &ch : tv) {
...
}Text_view provides interfaces for the following:
- Encoding and decoding of text for the encodings listed in supported encodings.
- Encoding text using C++11 compliant output iterators.
- Decoding text using input, forward, bidirectional, and random access iterators that are compliant with standard iterator requirements as specified in the ranges proposal.
- Constructing view adapters for encoded text stored in arrays, containers, or std::basic_string, or referenced by another range or view. These view adapters meet the requirements for views in the ranges proposal.
Text_view does not currently provide interfaces for the following:
- Transcoding of code points from one character set to another.
- Iterators for grapheme clusters or other boundary conditions.
- Collation.
- Localization.
- Internationalization.
- Unicode code point properties.
- Unicode normalization.
Text_view requires a C++ compiler that implements ISO/IEC technical specification 19217:2015, C++ Extensions for concepts As of 2016-08-26, this specification is only supported by gcc release 6.2.0 or later. Additionally, Text_view depends on the cmcstl2 implementation of the ranges proposal for concept definitions.
This section provides instructions for building Text_view and suitable versions of its dependencies.
Building and installing gcc
Text_view requires gcc version 6.2.0 or later. The following commands can be used to perform a suitable build of the current in-development release of gcc on Linux if an installation of gcc 6.2.0 or later is not available. If you have an installation of gcc 6.2.0 or later available, then there is no need to build gcc yourself.
$ svn co svn://gcc.gnu.org/svn/gcc/trunk gcc-trunk-src
$ curl -O ftp://ftp.gnu.org/gnu/gmp/gmp-5.1.1.tar.bz2
$ curl -O ftp://ftp.gnu.org/gnu/mpfr/mpfr-3.1.2.tar.bz2
$ curl -O ftp://ftp.gnu.org/gnu/mpc/mpc-1.0.1.tar.gz
$ cd gcc-trunk-src
$ svn update -r 234230 # Optional command to select a known good gcc version
$ bzip2 -d -c ../gmp-5.1.1.tar.bz2 | tar -xvf -
$ mv gmp-5.1.1 gmp
$ bzip2 -d -c ../mpfr-3.1.2.tar.bz2 | tar -xvf -
$ mv mpfr-3.1.2 mpfr
$ tar -zxvf ../mpc-1.0.1.tar.gz
$ mv mpc-1.0.1 mpc
$ cd ..
$ mkdir gcc-trunk-build
$ cd gcc-trunk-build
$ LIBRARY_PATH=/usr/lib/$(gcc -print-multiarch); export LIBRARY_PATH
$ CPATH=/usr/include/$(gcc -print-multiarch); export CPATH
$ ../gcc-trunk-src/configure \
CC=gcc \
CXX=g++ \
--prefix $(pwd)/../gcc-trunk-install \
--disable-multilib \
--disable-bootstrap \
--enable-languages=c,c++
$ make -j 4
$ make install
$ cd ..When complete, the new gcc build will be present in the gcc-trunk-install
directory.
Building and installing cmcstl2
Text_view only depends on headers provided by cmcstl2 and no build or
installation is required. Text_view is known to build successfully with
cmcstl2 git revision eb5ecdf79e22eb68c86cb62fd0912559593e5597. The
following commands can be used to checkout a known good revision.
$ git clone https://github.com/CaseyCarter/cmcstl2.git cmcstl2
$ cd cmcstl2
$ git checkout eb5ecdf79e22eb68c86cb62fd0912559593e5597Building and installing Text_view
Text_view has a CMake based build system suff
10000
icient to build and run its
tests, to validate example code, and to perform a minimal installation following
established operating system conventions. By default, files will be installed
under /usr/local on UNIX and UNIX-like systems, and under C:\Program Files
on Windows. The installation location can be changed by invoking cmake with
a -DCMAKE_INSTALL_PREFIX=<path> option. On UNIX and UNIX-like systems, header
files will be installed in the include directory of the installation
destination, and other files will be installed under share/text_view. On
Windows, header files be installed in the text_view\include directory of the
installation destination, and other files will be installed under text_view.
Unless cmcstl2 is installed to a common location, it will be necessary to
inform the build where it is installed. This is typically done by setting the
CMCSTL2_INSTALL_PATH environment variable. As of this writing, cmcstl2
does not provide an installation option, so CMCSTL2_INSTALL_PATH should
specify the location where the cmcstl2 source resides (the directory that
contains the cmcstl2 include directory).
The following commands suffice to build and run tests and examples, and perform
an installation. If the build succeeds, built test and example programs will
be present in the test and examples subdirectories of the build directory
(the built test and example programs are not installed), and header files,
example code, cmake package configuration modules, and other miscellaneous files
will be present in the installation directory.
$ vi setenv.sh # Update GCC_INSTALL_PATH and CMCSTL2_INSTALL_PATH.
$ . ./setenv.sh
$ mkdir build
$ cd build
$ cmake .. [-DCMAKE_INSTALL_PREFIX=/path/to/install/to]
$ cmake --build . --target install
$ ctestcheck and check-install CMake targets are also available for automating
build and test. The check target performs a build without installation and
then runs the tests. The check-install target performs a build, runs tests,
installs to a location within the build directory, and then performs tests
(verifying that example code builds) on the installation.
The installation includes a CMake based build system for building the example
code. To build all of the examples, run cmake specifying the examples
directory of the installation as the source directory. Alternatively, each
example can be built independently by specifying its source directory as the
source directory in a cmake invocation. If the installation was to a
non-default installation location (-DCMAKE_INSTALL_PREFIX was specified),
then it may be necessary to set CMAKE_PREFIX_PATH to the Text_view
installation location (the location CMAKE_INSTALL_PREFIX was set to) or
text_view_DIR to the directory containing the installed
text_view-config.cmake file, so that the Text_view package configuration
file is found. See the CMake documentation for more details.
The following commands suffice to build all of the installed examples.
$ cd /path/to/installation/text_view/examples
$ mkdir build
$ cd build
$ cmake .. [-DCMAKE_PREFIX_PATH=/path/to/installation]
$ cmake --build .
$ ctestTo use Text_view in your own code, perform a build and installation as
described above, add include paths for the text_view/include and cmcstl2
installation locations, add a library search path for the text_view/lib
directory, include the text_view header file in your sources, and link the
text_view library with your executable.
#include <experimental/text_view>Text_view installations include a CMake package configuration file suitable
for use in CMake based projects. To use it, specify text_view as the
<package> argument to find_package in your CMake file and add invocations
of target_link_libraries for each relevant target with the <lib> argument
set to text-view. This will automatically apply compiler and linker options
required to use Text_view to each target. See the CMakeLists.txt files for
the utilities under the examples directory for reference. If Text_view was
installed to a non-default installation location (-DCMAKE_INSTALL_PREFIX was
specified), then it may be necessary to set CMAKE_PREFIX_PATH to the
Text_view installation location (the location CMAKE_INSTALL_PREFIX was set
to) or text_view_DIR to the directory containing the installed
text_view-config.cmake file, so that the Text_view package configuration
file is found. It is also possible to use the build directory as a
(non-relocatable) installation directory by setting The CMAKE_PREFIX_PATH
or text_view_DIR variables appropriately. See the CMake documentation for
more details. The CMakeLists.txt files provided with the installed examples
exemplify a minimal CMake based build system for a downstream consumer of
Text_view.
All interfaces intended for public use are declared in the
std::experimental::text namespace. The text namespace is an inline
namespace, so all entities are available from the std::experimental namespace
itself.
The interface descriptions in the sections that follow use the concept names from the ranges proposal, are intended to be used as specification, and should be considered authoritative. Any differences in behavior as defined by these definitions as compared to the Text_view implementation are unintentional and should be considered indicatative of a defect in either the specification or the implementation.
namespace std {
namespace experimental {
inline namespace text {
// concepts:
template<typename T> concept bool CodeUnit();
template<typename T> concept bool CodePoint();
template<typename T> concept bool CharacterSet();
template<typename T> concept bool Character();
template<typename T> concept bool CodeUnitIterator();
template<typename T, typename V> concept bool CodeUnitOutputIterator();
template<typename T> concept bool TextEncodingState();
template<typename T> concept bool TextEncodingStateTransition();
template<typename T> concept bool TextErrorPolicy();
template<typename T> concept bool TextEncoding();
template<typename T, typename I> concept bool TextEncoder();
template<typename T, typename I> concept bool TextForwardDecoder();
template<typename T, typename I> concept bool TextBidirectionalDecoder();
template<typename T, typename I> concept bool TextRandomAccessDecoder();
template<typename T> concept bool TextIterator();
template<typename T, typename I> concept bool TextSentinel();
template<typename T> concept bool TextOutputIterator();
template<typename T> concept bool TextInputIterator();
template<typename T> concept bool TextForwardIterator();
template<typename T> concept bool TextBidirectionalIterator();
template<typename T> concept bool TextRandomAccessIterator();
template<typename T> concept bool TextView();
template<typename T> concept bool TextInputView();
template<typename T> concept bool TextForwardView();
template<typename T> concept bool TextBidirectionalView();
template<typename T> concept bool TextRandomAccessView();
// error policies:
class text_error_policy;
class text_strict_error_policy;
class text_permissive_error_policy;
using text_default_error_policy = text_strict_error_policy;
// error handling:
enum class encode_status : int {
no_error = /* implementation-defined */,
invalid_character = /* implementation-defined */,
invalid_state_transition = /* implementation-defined */
};
enum class decode_status : int {
no_error = /* implementation-defined */,
no_character = /* implementation-defined */,
invalid_code_unit_sequence = /* implementation-defined */,
underflow = /* implementation-defined */
};
constexpr inline bool status_ok(encode_status es) noexcept;
constexpr inline bool status_ok(decode_status ds) noexcept;
constexpr inline bool error_occurred(encode_status es) noexcept;
constexpr inline bool error_occurred(decode_status ds) noexcept;
const char* status_message(encode_status es) noexcept;
const char* status_message(decode_status ds) noexcept;
// exception classes:
class text_error;
class text_encode_error;
class text_decode_error;
// character sets:
class any_character_set;
class basic_execution_character_set;
class basic_execution_wide_character_set;
class unicode_character_set;
// implementation defined character set type aliases:
using execution_character_set = /* implementation-defined */ ;
using execution_wide_character_set = /* implementation-defined */ ;
using universal_character_set = /* implementation-defined */ ;
// character set identification:
class character_set_id;
template<CharacterSet CST>
inline character_set_id get_character_set_id();
// character set information:
class character_set_info;
template<CharacterSet CST>
inline const character_set_info& get_character_set_info();
const character_set_info& get_character_set_info(character_set_id id);
// character set and encoding traits:
template<typename T>
using code_unit_type_t = /* implementation-defined */ ;
template<typename T>
using code_point_type_t = /* implementation-defined */ ;
template<typename T>
using character_set_type_t = /* implementation-defined */ ;
template<typename T>
using character_type_t = /* implementation-defined */ ;
template<typename T>
using encoding_type_t = /* implementation-defined */ ;
template<typename T>
using default_encoding_type_t = /* implementation-defined */ ;
// characters:
template<CharacterSet CST> class character;
template <> class character<any_character_set>;
template<CharacterSet CST>
bool operator==(const character<any_character_set> &lhs,
const character<CST> &rhs);
template<CharacterSet CST>
bool operator==(const character<CST> &lhs,
const character<any_character_set> &rhs);
template<CharacterSet CST>
bool operator!=(const character<any_character_set> &lhs,
const character<CST> &rhs);
template<CharacterSet CST>
bool operator!=(const character<CST> &lhs,
const character<any_character_set> &rhs);
// encoding state and transition types:
class trivial_encoding_state;
class trivial_encoding_state_transition;
class utf8bom_encoding_state;
class utf8bom_encoding_state_transition;
class utf16bom_encoding_state;
class utf16bom_encoding_state_transition;
class utf32bom_encoding_state;
class utf32bom_encoding_state_transition;
// encodings:
class basic_execution_character_encoding;
class basic_execution_wide_character_encoding;
#if defined(__STDC_ISO_10646__)
class iso_10646_wide_character_encoding;
#endif // __STDC_ISO_10646__
class utf8_encoding;
class utf8bom_encoding;
class utf16_encoding;
class utf16be_encoding;
class utf16le_encoding;
class utf16bom_encoding;
class utf32_encoding;
class utf32be_encoding;
class utf32le_encoding;
class utf32bom_encoding;
// implementation defined encoding type aliases:
using execution_character_encoding = /* implementation-defined */ ;
using execution_wide_character_encoding = /* implementation-defined */ ;
using char8_character_encoding = /* implementation-defined */ ;
using char16_character_encoding = /* implementation-defined */ ;
using char32_character_encoding = /* implementation-defined */ ;
// itext_iterator:
template<TextEncoding ET,
ranges::View VT,
TextErrorPolicy TEP = text_default_error_policy>
requires TextForwardDecoder<ET, /* implementation-defined */ >()
class itext_iterator;
// itext_sentinel:
template<TextEncoding ET,
ranges::View VT,
TextErrorPolicy TEP = text_default_error_policy>
class itext_sentinel;
// otext_iterator:
template<TextEncoding ET,
CodeUnitOutputIterator<code_unit_type_t<ET>> CUIT,
TextErrorPolicy TEP = text_default_error_policy>
class otext_iterator;
// otext_iterator factory functions:
template<TextEncoding ET,
TextErrorPolicy TEP,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(typename ET::state_type state, IT out)
-> otext_iterator<ET, IT>;
template<TextEncoding ET,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(typename ET::state_type state, IT out)
-> otext_iterator<ET, IT>;
template<TextEncoding ET,
TextErrorPolicy TEP,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(IT out)
-> otext_iterator<ET, IT>;
template<TextEncoding ET,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(IT out)
-> otext_iterator<ET, IT>;
// basic_text_view:
template<TextEncoding ET,
ranges::View VT,
TextErrorPolicy TEP = text_default_error_policy>
class basic_text_view;
// basic_text_view type aliases:
using text_view = basic_text_view<execution_character_encoding,
/* implementation-defined */ >;
using wtext_view = basic_text_view<execution_wide_character_encoding,
/* implementation-defined */ >;
using u8text_view = basic_text_view<char8_character_encoding,
/* implementation-defined */ >;
using u16text_view = basic_text_view<char16_character_encoding,
/* implementation-defined */ >;
using u32text_view = basic_text_view<char32_character_encoding,
/* implementation-defined */ >;
// basic_text_view factory functions:
template<TextEncoding ET, ranges::InputIterator IT, ranges::Sentinel<IT> ST>
auto make_text_view(typename ET::state_type state, IT first, ST last)
-> basic_text_view<ET, /* implementation-defined */ >;
template<ranges::InputIterator IT, ranges::Sentinel<IT> ST>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<IT>>::state_type state,
IT first,
ST last)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET, ranges::InputIterator IT, ranges::Sentinel<IT> ST>
auto make_text_view(IT first, ST last)
-> basic_text_view<ET, /* implementation-defined */ >;
template<ranges::InputIterator IT, ranges::Sentinel<IT> ST>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(IT first, ST last)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET, ranges::ForwardIterator IT>
auto make_text_view(typename ET::state_type state,
IT first,
typename std::make_unsigned<ranges::difference_type_t<IT>>::type n)
-> basic_text_view<ET, /* implementation-defined */ >;
template<ranges::ForwardIterator IT>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(typename typename default_encoding_type_t<ranges::value_type_t<IT>>::state_type state,
IT first,
typename std::make_unsigned<ranges::difference_type_t<IT>>::type n)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET, ranges::ForwardIterator IT>
auto make_text_view(IT first,
typename std::make_unsigned<ranges::difference_type_t<IT>>::type n)
-> basic_text_view<ET, /* implementation-defined */ >;
template<ranges::ForwardIterator IT>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(IT first,
typename std::make_unsigned<ranges::difference_type_t<IT>>::type n)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET, ranges::InputRange Iterable>
auto make_text_view(typename ET::state_type state,
const Iterable &iterable)
-> basic_text_view<ET, /* implementation-defined */ >;
template<ranges::InputRange Iterable>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>::state_type state,
const Iterable &iterable)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>, /* implementation-defined */ >;
template<TextEncoding ET, ranges::InputRange Iterable>
auto make_text_view(const Iterable &iterable)
-> basic_text_view<ET, /* implementation-defined */ >;
template<ranges::InputRange Iterable>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>;
}
auto make_text_view(const Iterable &iterable)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>, /* implementation-defined */ >;
template<TextInputIterator TIT, TextSentinel<TIT> TST>
auto make_text_view(TIT first, TST last)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextView TVT>
TVT make_text_view(TVT tv);
} // inline namespace text
} // namespace experimental
} // namespace std- Concept CodeUnit
- Concept CodePoint
- Concept CharacterSet
- Concept Character
- Concept CodeUnitIterator
- Concept CodeUnitOutputIterator
- Concept TextEncodingState
- Concept TextEncodingStateTransition
- Concept TextErrorPolicy
- Concept TextEncoding
- Concept TextEncoder
- Concept TextForwardDecoder
- Concept TextBidirectionalDecoder
- Concept TextRandomAccessDecoder
- Concept TextIterator
- Concept TextSentinel
- Concept TextOutputIterator
- Concept TextInputIterator
- Concept TextForwardIterator
- Concept TextBidirectionalIterator
- Concept TextRandomAccessIterator
- Concept TextView
- Concept TextInputView
- Concept TextForwardView
- Concept TextBidirectionalView
- Concept TextRandomAccessView
The CodeUnit concept specifies requirements for a type usable as the
code unit type of a string type.
template<typename T> concept bool CodeUnit() {
return /* implementation-defined */ ;
}CodeUnit<T>() is satisfied if and only if
std::is_integral<T>::value is true and at least one of
std::is_unsigned<T>::value is true,
std::is_same<std::remove_cv_t<T>, char>::value is true, or
std::is_same<std::remove_cv_t<T>, wchar_t>::value is true.
The CodePoint concept specifies requirements for a type usable as the
code point type of a character set type.
template<typename T> concept bool CodePoint() {
return /* implementation-defined */ ;
}CodePoint<T>() is satisfied if and only if
std::is_integral<T>::value is true and at least one of
std::is_unsigned<T>::value is true,
std::is_same<std::remove_cv_t<T>, char>::value is true, or
std::is_same<std::remove_cv_t<T>, wchar_t>::value is true.
The CharacterSet concept specifies requirements for a type that describes
a character set. Such a type has a member typedef-name
declaration for a type that satisfies CodePoint, a static member function
that returns a name for the character set, and a static
member function that returns a code point value to be used to construct a
substitution character to stand in when errors occur during encoding and
decoding operations when the permissive error policy is in effect.
template<typename T> concept bool CharacterSet() {
return CodePoint<code_point_type_t<T>>()
&& requires () {
{ T::get_name() } noexcept -> const char *;
{ T::get_substitution_code_point() } noexcept -> code_point_type_t<T>;
};
}The Character concept specifies requirements for a type that describes a
character as defined by an associated
character set. Non-static member functions provide access to
the code point value of the described character.
Types that satisfy Character are regular and copyable.
template<typename T> concept bool Character() {
return ranges::Regular<T>()
&& ranges::Constructible<T, code_point_type_t<character_set_type_t<T>>>()
&& CharacterSet<character_set_type_t<T>>()
10000
&& requires (T t,
const T ct,
code_point_type_t<character_set_type_t<T>> cp)
{
{ t.set_code_point(cp) } noexcept;
{ ct.get_code_point() } noexcept
-> code_point_type_t<character_set_type_t<T>>;
{ ct.get_character_set_id() }
-> character_set_id;
};
}The CodeUnitIterator concept specifies requirements of an iterator that
has a value type that satisfies CodeUnit.
template<typename T> concept bool CodeUnitIterator() {
return ranges::Iterator<T>()
&& CodeUnit<ranges::value_type_t<T>>();
}The CodeUnitOutputIterator concept specifies requirements of an output
iterator that can be assigned from a type that satisfies CodeUnit.
template<typename T, typename V> concept bool CodeUnitOutputIterator() {
return ranges::OutputIterator<T, V>()
&& CodeUnit<V>();
}The TextEncodingState concept specifies requirements of types that hold
encoding state. Such types are semiregular.
template<typename T> concept bool TextEncodingState() {
return ranges::Semiregular<T>();
}The TextEncodingStateTransition concept specifies requirements of types
that hold encoding state transitions. Such types are
semiregular.
template<typename T> concept bool TextEncodingStateTransition() {
return ranges::Semiregular<T>();
}The TextErrorPolicy concept specifies requirements of types used
to specify error handling policies. Such types are semiregular class types
that derive from class text_error_policy.
template<typename T> concept bool TextErrorPolicy() {
return ranges::Semiregular<T>()
&& ranges::DerivedFrom<T, text_error_policy>()
&& !ranges::Same<std::remove_cv_t<T>, text_error_policy>();
}The TextEncoding concept specifies requirements of types that define an
encoding. Such types define member types that identify the
code unit, character, encoding state, and encoding
state transition types, a static member function that returns an initial
encoding state object that defines the encoding state at the beginning of a
sequence of encoded characters, and static data members that specify the
minimum and maximum number of code units used to encode any
single character.
template<typename T> concept bool TextEncoding() {
return requires () {
{ T::min_code_units } noexcept -> int;
{ T::max_code_units } noexcept -> int;
}
&& TextEncodingState<typename T::state_type>()
&& TextEncodingStateTransition<typename T::state_transition_type>()
&& CodeUnit<code_unit_type_t<T>>()
&& Character<character_type_t<T>>()
&& requires () {
{ T::initial_state() } noexcept
-> const typename T::state_type&;
};
}The TextEncoder concept specifies requirements of types that are used to
encode characters using a particular code unit
iterator that satisfies OutputIterator. Such a type satisifies
TextEncoding and defines static member functions used to encode state
transitions and characters.
template<typename T, typename I> concept bool TextEncoder() {
return TextEncoding<T>()
&& ranges::OutputIterator<CUIT, code_unit_type_t<T>>()
&& requires (
typename T::state_type &state,
CUIT &out,
typename T::state_transition_type stt,
int &encoded_code_units)
{
{ T::encode_state_transition(state, out, stt, encoded_code_units) }
-> encode_status;
}
&& requires (
typename T::state_type &state,
CUIT &out,
character_type_t<T> c,
int &encoded_code_units)
{
{ T::encode(state, out, c, encoded_code_units) }
-> encode_status;
};
}The TextForwardDecoder concept specifies requirements of types that are used
to decode characters using a particular code unit
iterator that satisifies ForwardIterator. Such a type satisfies
TextEncoding and defines a static member function used to decode state
transitions and characters.
template<typename T, typename I> concept bool TextForwardDecoder() {
return TextEncoding<T>()
&& ranges::ForwardIterator<CUIT>()
&& ranges::ConvertibleTo<ranges::value_type_t<CUIT>,
code_unit_type_t<T>>()
&& requires (
typename T::state_type &state,
CUIT &in_next,
CUIT in_end,
character_type_t<T> &c,
int &decoded_code_units)
{
{ T::decode(state, in_next, in_end, c, decoded_code_units) }
-> decode_status;
};
}The TextBidirectionalDecoder concept specifies requirements of types that
are used to decode characters using a particular
code unit iterator that satisifies BidirectionalIterator. Such
a type satisfies TextForwardDecoder and defines a static member function
used to decode state transitions and characters in the reverse
order of their encoding.
template<typename T, typename I> concept bool TextBidirectionalDecoder() {
return TextForwardDecoder<T, CUIT>()
&& ranges::BidirectionalIterator<CUIT>()
&& requires (
typename T::state_type &state,
CUIT &in_next,
CUIT in_end,
character_type_t<T> &c,
int &decoded_code_units)
{
{ T::rdecode(state, in_next, in_end, c, decoded_code_units) }
-> decode_status;
};
}The TextRandomAccessDecoder concept specifies requirements of types that
are used to decode characters using a particular
code unit iterator that satisifies RandomAccessIterator. Such a
type satisfies TextBidirectionalDecoder, requires that the minimum and
maximum number of code units used to encode any character have
the same value, and that the encoding state be an empty type.
template<typename T, typename I> concept bool TextRandomAccessDecoder() {
return TextBidirectionalDecoder<T, CUIT>()
&& ranges::RandomAccessIterator<CUIT>()
&& T::min_code_units == T::max_code_units
&& std::is_empty<typename T::state_type>::value;
}The TextIterator concept specifies requirements of iterator types that are
used to encode and decode characters as an encoded
sequence of code units. Encoding state and error
indication is held in each iterator instance and is made accessible via
non-static member functions.
template<typename T> concept bool TextIterator() {
return ranges::Iterator<T>()
&& TextEncoding<encoding_type_t<T>>()
&& TextErrorPolicy<typename T::error_policy>()
&& TextEncodingState<typename T::state_type>()
&& requires (const T ct) {
{ ct.state() } noexcept
-> const typename encoding_type_t<T>::state_type&;
{ ct.error_occurred() } noexcept
-> bool;
};
}The TextSentinel concept specifies requirements of types that are used to
mark the end of a range of encoded characters. A type T that
satisfies TextIterator also satisfies TextSentinel<T> there by enabling
TextIterator types to be used as sentinels.
template<typename T, typename I> concept bool TextSentinel() {
return ranges::Sentinel<T, I>()
&& TextIterator<I>()
&& TextErrorPolicy<typename T::error_policy>();
}The TextOutputIterator concept refines TextIterator with a requirement that
the type also satisfy ranges::OutputIterator for the character type of the
associated encoding and that a member function be provided for retrieving error
information.
template<typename T> concept bool TextOutputIterator() {
return TextIterator<I>();
&& ranges::OutputIterator<T, character_type_t<encoding_type_t<T>>>()
&& requires (const T ct) {
{ ct.get_error() } noexcept
-> encode_status;
};
}The TextInputIterator concept refines TextIterator with requirements that
the type also satisfy ranges::InputIterator, that the iterator value type
satisfy Character, and that a member function be provided for retrieving error
information.
template<typename T> concept bool TextInputIterator() {
return TextIterator<T>()
&& ranges::InputIterator<T>()
&& Character<ranges::value_type_t<T>>()
&& requires (const T ct) {
{ ct.get_error() } noexcept
-> decode_status;
};
}The TextForwardIterator concept refines TextInputIterator with a requirement
that the type also satisfy ranges::ForwardIterator.
template<typename T> concept bool TextForwardIterator() {
return TextInputIterator<T>()
&& ranges::ForwardIterator<T>();
}The TextBidirectionalIterator concept refines TextForwardIterator with a
requirement that the type also satisfy ranges::BidirectionalIterator.
template<typename T> concept bool TextBidirectionalIterator() {
return TextForwardIterator<T>()
&& ranges::BidirectionalIterator<T>();
}The TextRandomAccessIterator concept refines TextBidirectionalIterator with
a requirement that the type also satisfy ranges::RandomAccessIterator.
template<typename T> concept bool TextRandomAccessIterator() {
return TextBidirectionalIterator<T>()
&& ranges::RandomAccessIterator<T>();
}The TextView concept specifies requirements of types that provide view access
to an underlying code unit range. Such types satisfy
ranges::View, provide iterators that satisfy TextIterator, define member
types that identify the encoding, encoding state, and underlying
code unit range and iterator types. Non-static member functions
are provided to access the underlying code unit range and initial
encoding state.
Types that satisfy TextView do not own the underlying code unit
range and are copyable in constant time. The lifetime of the underlying range
must exceed the lifetime of referencing TextView objects.
template<typename T> concept bool TextView() {
return ranges::View<T>()
R& TextIterator<ranges::iterator_t<T>>()
&& TextEncoding<encoding_type_t<T>>()
&& ranges::View<typename T::view_type>()
&& TextErrorPolicy<typename T::error_policy>()
&& TextEncodingState<typename T::state_type>()
&& CodeUnitIterator<code_unit_iterator_t<T>>()
R& requires (T t, const T ct) {
{ ct.base() } noexcept
-> const typename T::view_type&;
{ ct.initial_state() } noexcept
-> const typename T::state_type&;
};
}The TextInputView concept refines TextView with a requirement that the
view's iterator type also satisfy TextInputIterator.
template<typename T> concept bool TextInputView() {
return TextView<T>()
&& TextInputIterator<ranges::iterator_t<T>>();
}The TextForwardView concept refines TextInputView with a requirement that
the view's iterator type also satisfy TextForwardIterator.
template<typename T> concept bool TextForwardView() {
return TextInputView<T>()
&& TextForwardIterator<ranges::iterator_t<T>>();
}The TextBidirectionalView concept refines TextForwardView with a requirement
that the view's iterator type also satisfy TextBidirectionalIterator.
template<typename T> concept bool TextBidirectionalView() {
return TextForwardView<T>()
&& TextBidirectionalIterator<ranges::iterator_t<T>>();
}The TextRandomAccessView concept refines TextBidirectionalView with a
requirement that the view's iterator type also satisfy
TextRandomAccessIterator.
template<typename T> concept bool TextRandomAccessView() {
return TextBidirectionalView<T>()
&& TextRandomAccessIterator<ranges::iterator_t<T>>();
}- Class text_error_policy
- Class text_strict_error_policy
- Class text_permissive_error_policy
- Alias text_default_error_policy
Class text_error_policy is a base class from which all text error policy
classes must derive.
class text_error_policy {};The text_strict_error_policy class is a policy class that specifies that
exceptions be thrown for errors that occur during encoding and decoding
operations initiated through text iterators. This class satisfies
TextErrorPolicy.
class text_strict_error_policy : public text_error_policy {};The class_text_permissive_error_policy class is a policy class that specifies
that substitution characters such as the Unicode replacement character
U+FFFD be substituted in place of errors that occur during encoding and
decoding operations initiated through text iterators. This class satisfies
TextErrorPolicy.
class text_permissive_error_policy : public text_error_policy {};The text_default_error_policy alias specifies the default text error policy.
Conforming implementations must alias this to text_strict_error_policy, but
may have options to select an alternative default policy for environments that
do not support exceptions. The referred class shall satisfy TextErrorPolicy.
using text_default_error_policy = text_strict_error_policy;The encode_status enumeration type defines enumerators used to report errors
that occur during text encoding operations.
The no_error enumerator indicates that no error has occurred.
The invalid_character enumerator indicates that an attempt was made to encode
a character that was not valid for the encoding.
The invalid_state_transition enumerator indicates that an attempt was made to
encode a state transition that was not valid for the encoding.
enum class encode_status : int {
no_error = /* implementation-defined */,
invalid_character = /* implementation-defined */,
invalid_state_transition = /* implementation-defined */
};The decode_status enumeration type defines enumerators used to report errors
that occur during text decoding operations.
The no_error enumerator indicates that no error has occurred.
The no_character enumerator indicates that no error has occurred, but that no
character was decoded for a code unit sequence. This typically indicates that
the code unit sequence represents an encoding state transition such as for an
escape sequence or byte order marker.
The invalid_code_unit_sequence enumerator indicates that an attempt was made
to decode an invalid code unit sequence.
The underflow enumerator indicates that the end of the input range was
encountered before a complete code unit sequence was decoded.
enum class decode_status : int {
no_error = /* implementation-defined */,
no_character = /* implementation-defined */,
invalid_code_unit_sequence = /* implementation-defined */,
underflow =
BD94
/* implementation-defined */
};The status_ok function returns true if the encode_status argument value
is encode_status::no_error or if the decode_status argument is either of
decode_status::no_error or decode_status::no_character. false is
returned for all other values.
constexpr inline bool status_ok(encode_status es) noexcept;
constexpr inline bool status_ok(decode_status ds) noexcept;The error_occurred function returns false if the encode_status argument
value is encode_status::no_error or if the decode_status argument is either
of decode_status::no_error or decode_status::no_character. true is
returned for all other values.
constexpr inline bool error_occurred(encode_status es) noexcept;
constexpr inline bool error_occurred(decode_status ds) noexcept;The status_message function returns a pointer to a statically allocated
string containing a short description of the value of the encode_status or
decode_status argument.
const char* status_message(encode_status es) noexcept;
const char* status_message(decode_status ds) noexcept;The text_error class defines the base class for the types of objects
thrown as exceptions to report errors detected during text processing.
class text_error : public std::runtime_error
{
public:
using std::runtime_error::runtime_error;
};The text_encode_error class defines the types of objects thrown as exceptions
to report errors detected during encoding of a character. Objects
of this type are generally thrown in response to an attempt to encode a
character with an invalid code point value, or to
encode an invalid state transition.
class text_encode_error : public text_error
{
public:
explicit text_encode_error(encode_status es) noexcept;
const encode_status& status_code() const noexcept;
private:
encode_status es; // exposition only
};The text_decode_error class defines the types of objects thrown as exceptions
to report errors detected during decoding of a code unit sequence.
Objects of this type are generally thrown in response to an attempt to decode
an ill-formed code unit sequence, a code unit
sequence that specifies an invalid code point value, or a
code unit sequence that specifies an invalid state transition.
class text_decode_error : public text_error
{
public:
explicit text_decode_error(decode_status ds) noexcept;
const decode_status& status_code() const noexcept;
private:
decode_status ds; // exposition only
};- code_unit_type_t
- code_point_type_t
- character_set_type_t
- character_type_t
- encoding_type_t
- default_encoding_type_t
The code_unit_type_t type alias template provides convenient means for
selecting the associated code unit type of some other type,
such as an encoding type that satisfies TextEncoding. The
aliased type is the same as typename T::code_unit_type.
template<typename T>
using code_unit_type_t = /* implementation-defined */ ;The code_point_type_t type alias template provides convenient means for
selecting the associated code point type of some other type,
such as a type that satisfies CharacterSet or Character. The aliased
type is the same as typename T::code_point_type.
template<typename T>
using code_point_type_t = /* implementation-defined */ ;The character_set_type_t type alias template provides convenient means for
selecting the associated character set type of some other
type, such as a type that satisfies Character. The aliased type is the same
as typename T::character_set_type.
template<typename T>
using character_set_type_t = /* implementation-defined */ ;The character_type_t type alias template provides convenient means for
selecting the associated character type of some other type, such
as a type that satisfies TextEncoding. The aliased type is the same as
typename T::character_type.
template<typename T>
using character_type_t = /* implementation-defined */ ;The encoding_type_t type alias template provides convenient means for
selecting the associated encoding type of some other type, such
as a type that satisfies TextIterator or TextView. The aliased type is the
same as typename T::encoding_type.
template<typename T>
using encoding_type_t = /* implementation-defined */ ;The default_encoding_type_t type alias template resolves to the default
encoding type, if any, for a given type, such as a type that
satisfies CodeUnit. Specializations are provided for the following
cv-unqualified and reference removed fundamental types. Otherwise, the alias
will attempt to resolve against a default_encoding_type member type.
When std::remove_cv_t<std::remove_reference_t<T>> is ... |
the default encoding is ... |
|---|---|
char |
execution_character_encoding |
wchar_t |
execution_wide_character_encoding |
char16_t |
char16_character_encoding |
char32_t |
char32_character_encoding |
template<typename T>
using default_encoding_type_t = /* implementation-defined */ ;- Class any_character_set
- Class basic_execution_character_set
- Class basic_execution_wide_character_set
- Class unicode_character_set
- Character set type aliases
The any_character_set class provides a generic character set
type used when a specific character set type is unknown or
when the ability to switch between specific character sets
is required. This class satisfies the CharacterSet concept and has an
implementation defined code_point_type that is able to represent
code point values from all of the implementation provided
character set types. The code point returned by
get_substitution_code_point is implementation defined.
class any_character_set {
public:
using code_point_type = /* implementation-defined */;
static const char* get_name() noexcept {
return "any_character_set";
}
static constexpr code_point_type get_substitution_code_point() noexcept;
};The basic_execution_character_set class represents the basic execution
character set specified in [lex.charset]p3 of the C++11
standard. This class satisfies the CharacterSet concept and has a
code_point_type member type that aliases char. The code point returned by
get_substitution_code_point is the code point for the '?' character.
class basic_execution_character_set {
public:
using code_point_type = char;
static const char* get_name() noexcept {
return "basic_execution_character_set";
}
static constexpr code_point_type get_substitution_code_point() noexcept;
};The basic_execution_wide_character_set class represents the basic execution
wide character set specified in [lex.charset]p3 of the
C++11 standard. This class satisfies the CharacterSet
concept and has a code_point_type member type that aliases wchar_t. The
code point returned by get_substitution_code_point is the code point for the
L'?' character.
class basic_execution_wide_character_set {
public:
using code_point_type = wchar_t;
static const char* get_name() noexcept {
return "basic_execution_wide_character_set";
}
static constexpr code_point_type get_substitution_code_point() noexcept;
};The unicode_character_set class represents the Unicode
character sets. This class satisfies the CharacterSet
concept and has a code_point_type member type that aliases char32_t.
The code point returned by get_substitution_code_point is the U+FFFD
Unicode replacement character.
class unicode_character_set {
public:
using code_point_type = char32_t;
static const char* get_name() noexcept {
return "unicode_character_set";
}
static constexpr code_point_type get_substitution_code_point() noexcept;
};The execution_character_set,
execution_wide_character_set, and
universal_character_set type aliases reflect the implementation
defined execution, wide execution, and universal
character sets specified in [lex.charset]p2-3 of the C++
standard.
The character set aliased by execution_character_set must be
a superset of the basic_execution_character_set
character set. This alias refers to the
character set that the compiler assumes during
translation; the character set that the compiler uses when
translating characters specified by universal-character-name
designators in ordinary string literals, not the locale sensitive run-time
execution character set.
The character set aliased by execution_wide_character_set
must be a superset of the basic_execution_wide_character_set
character set. This alias refers to the
character set that the compiler assumes during
translation; the character set that the compiler uses when
translating characters specified by universal-character-name
designators in wide string literals, not the locale sensitive run-time
execution wide character set.
The character set aliased by universal_character_set must
be a superset of the unicode_character_set character set.
using execution_character_set = /* implementation-defined */ ;
using execution_wide_character_set = /* implementation-defined */ ;
using universal_character_set = /* implementation-defined */ ;The character_set_id class provides unique, opaque values used to identify
character sets at run-time. Values of this type are produced
by get_character_set_id() and can be passed to get_character_set_info() to
obtain character set information. Values of this type are
copy constructible, copy assignable, equality comparable, and strictly totally
ordered.
class character_set_id {
public:
character_set_id() = delete;
friend bool operator==(character_set_id lhs, character_set_id rhs) noexcept;
friend bool operator!=(character_set_id lhs, character_set_id rhs) noexcept;
friend bool operator<(character_set_id lhs, character_set_id rhs) noexcept;
friend bool operator>(character_set_id lhs, character_set_id rhs) noexcept;
friend bool operator<=(character_set_id lhs, character_set_id rhs) noexcept;
friend bool operator>=(character_set_id lhs, character_set_id rhs) noexcept;
};get_character_set_id() returns a unique, opaque value for the
character set type specified by the template parameter.
template<CharacterSet CST>
inline character_set_id get_character_set_id();The character_set_info class stores information about a
character set. Values of this type are produced by the
get_character_set_info() functions based on a character set
type or ID.
class character_set_info {
public:
character_set_info() = delete;
character_set_id get_id() const noexcept;
const char* get_name() const noexcept;
private:
character_set_id id; // exposition only
};The get_character_set_info() functions return a reference to a
character_set_info object based on a character set type or
ID.
const character_set_info& get_character_set_info(character_set_id id);
template<CharacterSet CST>
inline const character_set_info& get_character_set_info();Objects of character class template specialization type define a
character via the association of a code point
value and a character set. The specialization provided for
the any_character_set type is used to maintain a dynamic
character set association while specializations for other
character sets specify a static association. These types
satisfy the Character concept and are default constructible, copy
constructible, copy assignable, and equality comparable. Member functions
provide access to the code point and
character set ID values for the represented
character. Default constructed objects represent a null
character using a zero initialized code point
value.
Objects with different character set type are not equality
comparable with the exception that objects with a static
character set type of any_character_set are comparable with
objects with any static character set type. In this case,
objects compare equally if and only if their character set
ID and code point values match. Equality comparison between
objects with different static character set type is not
implemented to avoid potentially costly unintended implicit transcoding between
character sets.
template<CharacterSet CST>
class character {
public:
using character_set_type = CST;
using code_point_type = code_point_type_t<character_set_type>;
character() = default;
explicit character(code_point_type code_point) noexcept;
friend bool operator==(const character &lhs,
const character &rhs) noexcept;
friend bool operator!=(const character &lhs,
const character &rhs) noexcept;
void set_code_point(code_point_type code_point) noexcept;
code_point_type get_code_point() const noexcept;
static character_set_id get_character_set_id();
private:
code_point_type code_point; // exposition only
};
template<>
class character<any_character_set> {
public:
using character_set_type = any_character_set;
using code_point_type = code_point_type_t<character_set_type>;
character() = default;
explicit character(code_point_type code_point) noexcept;
character(character_set_id cs_id, code_point_type code_point) noexcept;
friend bool operator==(const character &lhs,
const character &rhs) noexcept;
friend bool operator!=(const character &lhs,
const character &rhs) noexcept;
void set_code_point(code_point_type code_point) noexcept;
code_point_type get_code_point() const noexcept;
void set_character_set_id(character_set_id new_cs_id) noexcept;
character_set_id get_character_set_id() const noexcept;
private:
character_set_id cs_id; // exposition only
code_point_type code_point; // exposition only
};
template<CharacterSet CST>
bool operator==(const character<any_character_set> &lhs,
const character<CST> &rhs);
template<CharacterSet CST>
bool operator==(const character<CST> &lhs,
const character<any_character_set> &rhs);
template<CharacterSet CST>
bool operator!=(const character<any_character_set> &lhs,
const character<CST> &rhs);
template<CharacterSet CST>
bool operator!=(const character<CST> &lhs,
const character<any_character_set> &rhs);- class trivial_encoding_state
- class trivial_encoding_state_transition
- Class basic_execution_character_encoding
- Class basic_execution_wide_character_encoding
- Class iso_10646_wide_character_encoding
- Class utf8_encoding
- Class utf8bom_encoding
- Class utf16_encoding
- Class utf16be_encoding
- Class utf16le_encoding
- Class utf16bom_encoding
- Class utf32_encoding
- Class utf32be_encoding
- Class utf32le_encoding
- Class utf32bom_encoding
- Encoding type aliases
The trivial_encoding_state class is an empty class used by stateless
encodings to implement the parts of the generic
encoding interfaces necessary to support stateful
encodings.
class trivial_encoding_state {};The trivial_encoding_state_transition class is an empty class used by
stateless encodings to implement the parts of the generic
encoding interfaces necessary to support stateful
encodings that support non-code-point
encoding co
F438
de unit sequences.
class trivial_encoding_state_transition {};The basic_execution_character_encoding class implements support for the
encoding used for ordinary string literals limited to support
for the basic execution character set as defined in [lex.charset]p3 of
the C++ standard.
This encoding is trivial, stateless, fixed width, supports
random access decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class basic_execution_character_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<basic_execution_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 1;
static constexpr int max_code_units = 1;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units
noexcept(/* implementation defined */);
};The basic_execution_wide_character_encoding class implements support for the
encoding used for wide string literals limited to support for the
basic execution wide-character set as defined in [lex.charset]p3 of
the C++ standard.
This encoding is trivial, stateless, fixed width, supports
random access decoding, and has a code unit of type wchar_t.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class basic_execution_wide_character_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<basic_execution_wide_character_set>;
using code_unit_type = wchar_t;
static constexpr int min_code_units = 1;
static constexpr int max_code_units = 1;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The iso_10646_wide_character_encoding class is only defined
when the __STDC_ISO_10646__ macro is defined.
The iso_10646_wide_character_encoding class implements support for the
encoding used for wide string literals when that
encoding uses the Unicode character set and
wchar_t is large enough to store the code point values of
all characters defined by the version of the Unicode standard
indicated by the value of the __STDC_ISO_10646__ macro as specified in
[cpp.predefined]p2 of the C++ standard.
This encoding is trivial, stateless, fixed width, supports random
access decoding, and has a code unit of type wchar_t.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
#if defined(__STDC_ISO_10646__)
class iso_10646_wide_character_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = wchar_t;
static constexpr int min_code_units = 1;
static constexpr int max_code_units = 1;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};
#endif // __STDC_ISO_10646__The utf8_encoding class implements support for the Unicode UTF-8
encoding.
This encoding is stateless, variable width, supports bidirectional
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class utf8_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 1;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<std::make_unsigned_t<code_unit_type>> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<std::make_unsigned_t<code_unit_type>> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf8bom_encoding class implements support for the Unicode UTF-8
encoding with a byte order mark (BOM).
This encoding is stateful, variable width, supports bidirectional
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
This encoding defines a state transition class that enables forcing or suppressing the encoding of a BOM, or influencing whether a decoded BOM code unit sequence represents a BOM or a code point.
class utf8bom_encoding_state {
/* implementation-defined */
};
class utf8bom_encoding_state_transition {
public:
static utf8bom_encoding_state_transition to_initial_state() noexcept;
static utf8bom_encoding_state_transition to_bom_written_state() noexcept;
static utf8bom_encoding_state_transition to_assume_bom_written_state() noexcept;
};
class utf8bom_encoding {
public:
using state_type = utf8bom_encoding_state;
using state_transition_type = utf8bom_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 1;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<std::make_unsigned_t<code_unit_type>> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<std::make_unsigned_t<code_unit_type>> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf16_encoding class implements support for the Unicode UTF-16
encoding.
This encoding is stateless, variable width, supports bidirectional
decoding, and has a code unit of type char16_t.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class utf16_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char16_t;
static constexpr int min_code_units = 1;
static constexpr int max_code_units = 2;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf16be_encoding class implements support for the Unicode UTF-16
big-endian encoding.
This encoding is stateless, variable width, supports bidirectional
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class utf16be_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 2;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf16le_encoding class implements support for the Unicode UTF-16
little-endian encoding.
This encoding is stateless, variable width, supports bidirectional
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class utf16le_encoding {
public:
10000
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 2;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf16bom_encoding_state class implements support for the Unicode UTF-16
encoding with a byte order mark (BOM).
This encoding is stateful, variable width, supports bidirectional
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
This encoding defines a state transition class that enables forcing or suppressing the encoding of a BOM, or influencing whether a decoded BOM code unit sequence represents a BOM or a code point.
class utf16bom_encoding_state {
/* implementation-defined */
};
class utf16bom_encoding_state_transition {
public:
static utf16bom_encoding_state_transition to_initial_state() noexcept;
static utf16bom_encoding_state_transition to_bom_written_state() noexcept;
static utf16bom_encoding_state_transition to_be_bom_written_state() noexcept;
static utf16bom_encoding_state_transition to_le_bom_written_state() noexcept;
static utf16bom_encoding_state_transition to_assume_bom_written_state() noexcept;
static utf16bom_encoding_state_transition to_assume_be_bom_written_state() noexcept;
static utf16bom_encoding_state_transition to_assume_le_bom_written_state() noexcept;
};
class utf16bom_encoding {
public:
using state_type = utf16bom_encoding_state;
using state_transition_type = utf16bom_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 2;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf32_encoding class implements support for the Unicode UTF-32
encoding.
This encoding is trivial, stateless, fixed width, supports
random access decoding, and has a code unit of type char32_t.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class utf32_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char32_t;
static constexpr int min_code_units = 1;
static constexpr int max_code_units = 1;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf32be_encoding class implements support for the Unicode UTF-32
big-endian encoding.
This encoding is stateless, fixed width, supports random access
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class utf32be_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 4;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf32le_encoding class implements support for the Unicode UTF-32
little-endian encoding.
This encoding is stateless, fixed width, supports random access
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
class utf32le_encoding {
public:
using state_type = trivial_encoding_state;
using state_transition_type = trivial_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 4;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The utf32bom_encoding class implements support for the Unicode UTF-32
encoding with a byte order mark (BOM).
This encoding is stateful, variable width, supports bidirectional
decoding, and has a code unit of type char.
Errors that occur during encoding and decoding operations are reported via
the encode_status and decode_status return types. Exceptions are not
directly thrown, but may propagate from operations performed on the
dependent code unit iterator.
This encoding defines a state transition class that enables forcing or suppressing the encoding of a BOM, or influencing whether a decoded BOM code unit sequence represents a BOM or a code point.
class utf32bom_encoding_state {
/* implementation-defined */
};
class utf32bom_encoding_state_transition {
public:
static utf32bom_encoding_state_transition to_initial_state() noexcept;
static utf32bom_encoding_state_transition to_bom_written_state() noexcept;
static utf32bom_encoding_state_transition to_be_bom_written_state() noexcept;
static utf32bom_encoding_state_transition to_le_bom_written_state() noexcept;
static utf32bom_encoding_state_transition to_assume_bom_written_state() noexcept;
static utf32bom_encoding_state_transition to_assume_be_bom_written_state() noexcept;
static utf32bom_encoding_state_transition to_assume_le_bom_written_state() noexcept;
};
class utf32bom_encoding {
public:
using state_type = utf32bom_encoding_state;
using state_transition_type = utf32bom_encoding_state_transition;
using character_type = character<unicode_character_set>;
using code_unit_type = char;
static constexpr int min_code_units = 4;
static constexpr int max_code_units = 4;
static const state_type& initial_state() noexcept;
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode_state_transition(state_type &state,
CUIT &out,
const state_transition_type &stt,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitOutputIterator<code_unit_type> CUIT>
static encode_status encode(state_type &state,
CUIT &out,
character_type c,
int &encoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status decode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
template<CodeUnitIterator CUIT, typename CUST>
requires ranges::ForwardIterator<CUIT>()
&& ranges::Convertible<ranges::value_type_t<CUIT>, code_unit_type>()
&& ranges::Sentinel<CUST, CUIT>()
static decode_status rdecode(state_type &state,
CUIT &in_next,
CUST in_end,
character_type &c,
int &decoded_code_units)
noexcept(/* implementation defined */);
};The execution_character_encoding,
execution_wide_character_encoding,
char8_character_encoding,
char16_character_encoding, and
char32_character_encoding type aliases reflect the implementation
defined encodings used for execution, wide execution, UTF-8,
char16_t, and char32_t string literals.
Each of these encodings carries a compatibility requirement with another encoding. Decode compatibility is satisfied when the following criteria is met.
- Text encoded by the compatibility encoding can be decoded by the aliased encoding.
- Text encoded by the aliased encoding can be decoded by the compatibility encoding when encoded characters are restricted to members of the character set of the compatibility encoding.
These compatibility requirements allow implementation freedom to use
encodings that provide features beyond the minimum requirements
imposed on the compatibility encodings by the standard. For
example, the encoding aliased by execution_character_encoding
is allowed to support characters that are not members of the
character set of the basic_execution_character_encoding
The encoding aliased by execution_character_encoding must be
decode compatible with the basic_execution_character_encoding
encoding.
The encoding aliased by execution_wide_character_encoding must
be decode compatible with the
basic_execution_wide_character_encoding encoding.
The encoding aliased by char8_character_encoding must be
decode compatible with the utf8_encoding encoding.
The encoding aliased by char16_character_encoding must be
decode compatible with the utf16_encoding encoding.
The encoding aliased by char32_character_encoding must be
decode compatible with the utf32_encoding encoding.
using execution_character_encoding = /* implementation-defined */ ;
using execution_wide_character_encoding = /* implementation-defined */ ;
using char8_character_encoding = /* implementation-defined */ ;
using char16_character_encoding = /* implementation-defined */ ;
using char32_character_encoding = /* implementation-defined */ ;- Class template itext_iterator
- Class template itext_sentinel
- Class template otext_iterator
- make_otext_iterator
Objects of itext_iterator class template specialization type provide a
standard iterator interface for enumerating the characters encoded
by the associated encoding ET in the code unit
sequence exposed by the associated view. These types satisfy the
TextInputIterator concept and are default constructible, copy and move
constructible, copy and move assignable, and equality comparable.
These types also conditionally satisfy ranges::ForwardIterator,
ranges::BidirectionalIterator, and ranges::RandomAccessIterator depending
on traits of the associated encoding ET and view VT as
described in the following table.
When ET and ranges::iterator_t<VT> satisfy ... |
then itext_iterator<ET, VT> satisfies ... |
and itext_iterator<ET, VT>::iterator_category is ... |
|---|---|---|
ranges::InputIterator<ranges::iterator_t<VT>> && ! ranges::ForwardIterator<ranges::iterator_t<VT>> && TextForwardDecoder<ET, /* implementation-defined */ > (With an internal adapter to provide forward iterator semantics over the input iterator) |
ranges::InputIterator |
std::input_iterator_tag |
TextForwardDecoder<ET, ranges::iterator_t<VT>> |
ranges::ForwardIterator |
std::forward_iterator_tag |
TextBidirectionalDecoder<ET, ranges::iterator_t<VT>> |
ranges::BidirectionalIterator |
std::bidirectional_iterator_tag |
TextRandomAccessDecoder<ET, ranges::iterator_t<VT>> |
ranges::RandomAccessIterator |
std::random_access_iterator_tag |
Member functions provide access to the stored encoding state, the
underlying code unit iterator, and the underlying
code unit range for the current character. The
underlying code unit range is returned with an implementation
defined type that satisfies ranges::View. The is_ok member function
returns true if the iterator is dereferenceable as a result of having
successfully decoded a code point (This predicate is used to
distinguish between an input iterator that just successfully decoded the last
code point in the code unit stream as compared to
one that was advanced after having done so; in both cases, the underlying
code unit input iterator will compare equal to the end
iterator).
The error_occurred and get_error member functions enable retrieving
information about errors that occurred during decoding operations. if a call
to error_occurred returns false, then it is guaranteed that a dereference
operation will not throw an exception; assuming a non-singular iterator that is
not past the end.
The look_ahead_range member function is provided only when the underlying
code unit iterator is an input iterator; it provides access to code units that
were read from the code unit iterator, but were not (yet) used to decode a
character. Generally such look ahead only occurs when an invalid code unit
sequence is encountered.
itext_iterator is a proxy iterator since the value type is computed
and a meaningful reference type cannot be provided for the dereference and
subscript operators. The reference member type is an alias of an
implementation defined proxy reference type, must satisfy Character, and must
support implicit conversion to const value_type&.
Note: Implementation of a reference proxy would be simplified if the operator dot proposal is adopted.
template<TextEncoding ET,
ranges::View VT,
TextErrorPolicy TEP = text_default_error_policy>
requires TextForwardDecoder<
ET,
/* implementation-defined */ >()
class itext_iterator {
public:
using encoding_type = ET;
using view_type = VT;
using error_policy = TEP;
using state_type = typename encoding_type::state_type;
using iterator = ranges::iterator_t<std::add_const_t<view_type>>;
using iterator_category = /* implementation-defined */;
using value_type = character_type_t<encoding_type>;
using reference = value_type;
using pointer = std::add_const_t<value_type>*;
using difference_type = ranges::difference_type_t<iterator>;
itext_iterator();
itext_iterator(state_type state,
const view_type *view,
iterator first);
reference operator*() const noexcept;
pointer operator->() const noexcept;
friend bool operator==(const
10000
itext_iterator &l, const itext_iterator &r);
friend bool operator!=(const itext_iterator &l, const itext_iterator &r);
friend bool operator<(const itext_iterator &l, const itext_iterator &r)
requires TextRandomAccessDecoder<encoding_type, iterator>();
friend bool operator>(const itext_iterator &l, const itext_iterator &r)
requires TextRandomAccessDecoder<encoding_type, iterator>();
friend bool operator<=(const itext_iterator &l, const itext_iterator &r)
requires TextRandomAccessDecoder<encoding_type, iterator>();
friend bool operator>=(const itext_iterator &l, const itext_iterator &r)
requires TextRandomAccessDecoder<encoding_type, iterator>();
itext_iterator& operator++();
itext_iterator& operator++()
requires TextForwardDecoder<encoding_type, iterator>();
itext_iterator operator++(int);
itext_iterator& operator--()
requires TextBidirectionalDecoder<encoding_type, iterator>();
itext_iterator operator--(int)
requires TextBidirectionalDecoder<encoding_type, iterator>();
itext_iterator& operator+=(difference_type n)
requires TextRandomAccessDecoder<encoding_type, iterator>();
itext_iterator& operator-=(difference_type n)
requires TextRandomAccessDecoder<encoding_type, iterator>();
friend itext_iterator operator+(itext_iterator l, difference_type n)
requires TextRandomAccessDecoder<encoding_type, iterator>();
friend itext_iterator operator+(difference_type n, itext_iterator r)
requires TextRandomAccessDecoder<encoding_type, iterator>();
friend itext_iterator operator-(itext_iterator l, difference_type n)
requires TextRandomAccessDecoder<encoding_type, iterator>();
friend difference_type operator-(const itext_iterator &l,
const itext_iterator &r)
requires TextRandomAccessDecoder<encoding_type, iterator>();
reference operator[](difference_type n) const
requires TextRandomAccessDecoder<encoding_type, iterator>();
const state_type& state() const noexcept;
const iterator& base() const noexcept;
/* implementation-defined */ base_range() const noexcept;
/* implementation-defined */ look_ahead_range() const noexcept
requires ! ranges::ForwardIterator<iterator>();
bool error_occurred() const noexcept;
decode_status get_error() const noexcept;
bool is_ok() const noexcept;
private:
state_type base_state; // exposition only
iterator base_iterator; // exposition only
bool ok; // exposition only
};Objects of itext_sentinel class template specialization type denote the end
of a range of text as delimited by a sentinel object for the underlying
code unit sequence. These types satisfy the TextSentinel
concept and are default constructible, copy and move constructible, and copy and
move assignable. Member functions provide access to the sentinel for the
underlying code unit sequence.
Objects of these types are equality comparable to itext_iterator objects that
have matching encoding and view types.
template<TextEncoding ET,
ranges::View VT,
TextErrorPolicy TEP = text_default_error_policy>
class itext_sentinel {
public:
using view_type = VT;
using error_policy = TEP;
using sentinel = ranges::sentinel_t<std::add_const_t<view_type>>;
itext_sentinel() = default;
itext_sentinel(sentinel s);
friend bool operator==(const itext_iterator<ET, VT, TEP> &ti,
const itext_sentinel &ts);
friend bool operator!=(const itext_iterator<ET, VT, TEP> &ti,
const itext_sentinel &ts);
friend bool operator==(const itext_sentinel &ts,
const itext_iterator<ET, VT, TEP> &ti);
friend bool operator!=(const itext_sentinel &ts,
const itext_iterator<ET, VT, TEP> &ti);
const sentinel& base() const noexcept;
private:
sentinel base_sentinel; // exposition only
};Objects of otext_iterator class template specialization type provide a
standard iterator interface for encoding characters in the form
implemented by the associated encoding ET. These types satisfy
the TextOutputIterator concept and are default constructible, copy and move
constructible, and copy and move assignable.
Member functions provide access to the stored encoding state and the underlying code unit output iterator.
The error_occurred and get_error member functions enable retrieving
information about errors that occurred during encoding operations.
template<TextEncoding ET,
CodeUnitOutputIterator<code_unit_type_t<ET>> CUIT,
TextErrorPolicy TEP = text_default_error_policy>
class otext_iterator {
public:
using encoding_type = ET;
using error_policy = TEP;
using state_type = typename ET::state_type;
using state_transition_type = typename ET::state_transition_type;
using iterator = CUIT;
using iterator_category = std::output_iterator_tag;
using value_type = character_type_t<encoding_type>;
using reference = value_type&;
using pointer = value_type*;
using difference_type = ranges::difference_type_t<iterator>;
otext_iterator();
otext_iterator(state_type state, iterator current);
otext_iterator& operator*() const noexcept;
otext_iterator& operator++() noexcept;
otext_iterator& operator++(int) noexcept;
otext_iterator& operator=(const state_transition_type &stt);
otext_iterator& operator=(const character_type_t<encoding_type> &value);
const state_type& state() const noexcept;
const iterator& base() const noexcept;
bool error_occurred() const noexcept;
encode_status get_error() const noexcept;
private:
state_type base_state; // exposition only
iterator base_iterator; // exposition only
};The make_otext_iterator functions enable convenient construction of
otext_iterator objects via type deduction of the underlying
code unit output iterator type. Overloads are provided to enable
construction with an explicit encoding state or the implicit
encoding dependent initial state.
template<TextEncoding ET,
TextErrorPolicy TEP,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(typename ET::state_type state, IT out)
-> otext_iterator<ET, IT>;
template<TextEncoding ET,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(typename ET::state_type state, IT out)
-> otext_iterator<ET, IT>;
template<TextEncoding ET,
TextErrorPolicy TEP,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(IT out)
-> otext_iterator<ET, IT>;
template<TextEncoding ET,
CodeUnitOutputIterator<code_unit_type_t<ET>> IT>
auto make_otext_iterator(IT out)
-> otext_iterator<ET, IT>;Objects of basic_text_view class template specialization type provide a view
of an underlying code unit sequence as a sequence of
characters. These types satisfy the TextView concept and are
default constructible, copy and move constructible, and copy and move
assignable. Member functions provide access to the underlying
code unit sequence and the initial encoding
state for the range.
Constructors are provided to construct objects of these types from objects of
the underlying code unit view type and from iterator and sentinel
pairs, iterator and difference pairs, and range or std::basic_string types for
which an object of the underlying code unit view type can be
constructed. For each of these, overloads are provided to construct the view
with an explicit encoding state or with an implicit initial
encoding state provided by the encoding ET.
The end of the view is represented with a sentinel type when the end of the
underlying code unit view is represented with a sentinel type or
when the encoding ET is a stateful encoding;
otherwise, the end of the view is represented with an iterator of the same type
as used for the beginning of the view.
template<TextEncoding ET,
ranges::View VT,
TextErrorPolicy TEP = text_default_error_policy>
class basic_text_view : public ranges::view_base {
public:
using encoding_type = ET;
using view_type = VT;
using error_policy = TEP;
using state_type = typename ET::state_type;
using code_unit_iterator = ranges::iterator_t<std::add_const_t<view_type>>;
using code_unit_sentinel = ranges::sentinel_t<std::add_const_t<view_type>>;
using iterator = itext_iterator<ET, VT, TEP>;
using sentinel = itext_sentinel<ET, VT, TEP>;
basic_text_view();
basic_text_view(state_type state,
view_type view);
basic_text_view(view_type view);
basic_text_view(state_type state,
code_unit_iterator first,
code_unit_sentinel last)
requires ranges::Constructible<view_type,
code_unit_iterator&&,
code_unit_sentinel&&>();
basic_text_view(code_unit_iterator first,
code_unit_sentinel last)
requires ranges::Constructible<view_type,
code_unit_iterator&&,
code_unit_sentinel&&>();
basic_text_view(state_type state,
code_unit_iterator first,
ranges::difference_type_t<code_unit_iterator> n)
requires ranges::Constructible<view_type,
code_unit_iterator,
code_unit_iterator>();
basic_text_view(code_unit_iterator first,
ranges::difference_type_t<code_unit_iterator> n)
requires ranges::Constructible<view_type,
code_unit_iterator,
code_unit_iterator>();
template<typename charT, typename traits, typename Allocator>
basic_text_view(state_type state,
const basic_string<charT, traits, Allocator> &str)
requires ranges::Constructible<code_unit_iterator, const charT *>()
&& ranges::ConvertibleTo<ranges::difference_type_t<code_unit_iterator>,
typename basic_string<charT, traits, Allocator>::size_type>()
&& ranges::Constructible<view_type,
code_unit_iterator,
code_unit_sentinel>();
template<typename charT, typename traits, typename Allocator>
basic_text_view(const basic_string<charT, traits, Allocator> &str)
requires ranges::Constructible<code_unit_iterator, const charT *>()
&& ranges::ConvertibleTo<ranges::difference_type_t<code_unit_iterator>,
typename basic_string<charT, traits, Allocator>::size_type>()
&& ranges::Constructible<view_type,
code_unit_iterator,
code_unit_sentinel>();
template<ranges::InputRange Iterable>
basic_text_view(state_type state,
const Iterable &iterable)
requires ranges::Constructible<code_unit_iterator,
ranges::iterator_t<const Iterable>>()
&& ranges::Constructible<view_type,
code_unit_iterator,
code_unit_sentinel>();
template<ranges::InputRange Iterable>
basic_text_view(const Iterable &iterable)
requires ranges::Constructible<code_unit_iterator,
ranges::iterator_t<const Iterable>>()
&& ranges::Constructible<view_type,
code_unit_iterator,
code_unit_sentinel>();
basic_text_view(iterator first, iterator last)
requires ranges::Constructible<code_unit_iterator,
decltype(std::declval<iterator>().base())>()
&& ranges::Constructible<view_type,
code_unit_iterator,
code_unit_iterator>();
basic_text_view(iterator first, sentinel last)
requires ranges::Constructible<code_unit_iterator,
decltype(std::declval<iterator>().base())>()
&& ranges::Constructible<view_type,
code_unit_iterator,
code_unit_sentinel>();
const view_type& base() const noexcept;
const state_type& initial_state() const noexcept;
iterator begin() const;
iterator end() const
requires std::is_empty<state_type>::value
&& ranges::Iterator<code_unit_sentinel>();
sentinel end() const
requires !std::is_empty<state_type>::value
|| !ranges::Iterator<code_unit_sentinel>();
private:
state_type base_state; // exposition only
view_type base_view; // exposition only
};
The text_view, wtext_view, u8text_view, u16text_view and
u32text_view type aliases reference an implementation defined specialization
of basic_text_view for all five of the encodings the standard
states must be provided.
The implementation defined view type used for the underlying
code unit view type must satisfy ranges::View and provide
iterators of pointer to the underlying code unit type to
contiguous storage. The intent in providing these type aliases is to minimize
instantiations of the basic_text_view and itext_iterator class templates by
encouraging use of common view types with underlying code unit
views that reference contiguous storage, such as views into objects with a type
instantiated from std::basic_string.
It is permissible for the text_view and u8text_view type aliases to
reference the same type. This will be the case when the execution character
encoding is UTF-8. Attempts to overload functions based on
text_view and u8text_view will result in multiple function
definition errors on such implementations.
using text_view = basic_text_view<
execution_character_encoding,
/* implementation-defined */ >;
using wtext_view = basic_text_view<
execution_wide_character_encoding,
/* implementation-defined */ >;
using u8text_view = basic_text_view<
char8_character_encoding,
/* implementation-defined */ >;
using u16text_view = basic_text_view<
char16_character_encoding,
/* implementation-defined */ >;
using u32text_view = basic_text_view<
char32_character_encoding,
/* implementation-defined */ >;The make_text_view functions enable convenient construction of
basic_text_view objects via implicit selection of a view type for the
underlying code unit sequence.
When provided iterators or ranges for contiguous storage, these functions return
a basic_text_view specialization type that uses the same implementation
defined view type as for the basic_text_view type
aliases as discussed in Text view type aliases.
Overloads are provided to construct basic_text_view objects from
iterator and sentinel pairs, iterator and difference pairs, and range or
std::basic_string objects. For each of these overloads, additional
overloads are provided to construct the view with an explicit
encoding state or with an implicit initial encoding
state provided by the encoding ET. Each of these overloads
requires that the encoding type be explicitly specified.
Additional overloads are provided to construct the view from iterator and
sentinel pairs that satisfy TextInputIterator and objects of a type that
satisfies TextView. For these overloads, the encoding type is
deduced and the encoding state is implicitly copied from the
arguments.
If make_text_view is invoked with an rvalue range, then the lifetime of the
returned object and all copies of it must end with the full-expression that the
make_text_view invocation is within. Otherwise, the returned object or its
copies will hold iterators into a destructed object resulting in undefined
behavior.
template<TextEncoding ET,
TextErrorPolicy TEP,
ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
auto make_text_view(typename ET::state_type state,
IT first, ST last)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextEncoding ET,
ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
auto make_text_view(typename ET::state_type state,
IT first, ST last)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<IT>>::state_type state,
IT first,
ST last)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<IT>>::state_type state,
IT first,
ST last)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET,
TextErrorPolicy TEP,
ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
auto make_text_view(IT first, ST last)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextEncoding ET,
ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
auto make_text_view(IT first, ST last)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(IT first,
ST last)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<ranges::InputIterator IT,
ranges::Sentinel<IT> ST>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(IT first,
ST last)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET,
TextErrorPolicy TEP,
ranges::ForwardIterator IT>
auto make_text_view(typename ET::state_type state,
IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextEncoding ET,
ranges::ForwardIterator IT>
auto make_text_view(typename ET::state_type state,
IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
ranges::ForwardIterator IT>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<IT>>::state_type state,
IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<ranges::ForwardIterator IT>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<IT>>::state_type state,
IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET,
TextErrorPolicy TEP,
ranges::ForwardIterator IT>
auto make_text_view(IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextEncoding ET,
ranges::ForwardIterator IT>
auto make_text_view(IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
ranges::ForwardIterator IT>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<ranges::ForwardIterator IT>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<IT>>;
}
auto make_text_view(IT first,
ranges::difference_type_t<IT> n)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<IT>>, /* implementation-defined */ >;
template<TextEncoding ET,
TextErrorPolicy TEP,
ranges::InputRange Iterable>
auto make_text_view(typename ET::state_type state,
const Iterable &iterable)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextEncoding ET,
ranges::InputRange Iterable>
auto make_text_view(typename ET::state_type state,
const Iterable &iterable)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
ranges::InputRange Iterable>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<RT>>>::state_type state,
const RT &range)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>, /* implementation-defined */ >;
template<ranges::InputRange Iterable>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>;
}
auto make_text_view(typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<RT>>>::state_type state,
const RT &range)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>, /* implementation-defined */ >;
template<TextEncoding ET,
TextErrorPolicy TEP,
ranges::InputRange Iterable>
auto make_text_view(const Iterable &iterable)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextEncoding ET,
ranges::InputRange Iterable>
auto make_text_view(const Iterable &iterable)
-> basic_text_view<ET, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
ranges::InputRange Iterable>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>;
}
auto make_text_view(
const RT &range)
-> basic_text_view<default_encoding_type_t<ranges::value
C1E4
_type_t<ranges::iterator_t<Iterable>>>, /* implementation-defined */ >;
template<ranges::InputRange Iterable>
requires requires () {
typename default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>;
}
auto make_text_view(
const RT &range)
-> basic_text_view<default_encoding_type_t<ranges::value_type_t<ranges::iterator_t<Iterable>>>, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
TextInputIterator TIT,
TextSentinel<TIT> TST>
auto make_text_view(TIT first, TST last)
-> basic_text_view<encoding_type_t<TIT>, /* implementation-defined */ >;
template<TextInputIterator TIT,
TextSentinel<TIT> TST>
auto make_text_view(TIT first, TST last)
-> basic_text_view<encoding_type_t<TIT>, /* implementation-defined */ >;
template<TextErrorPolicy TEP,
TextView TVT>
TVT make_text_view(TVT tv);
template<TextView TVT>
TVT make_text_view(TVT tv);As of 2015-12-31, supported encodings include:
| Encoding name | Description | Encoding type |
|---|---|---|
| execution_character_encoding | Type alias for the encoding of ordinary string literals (C++11 2.3p3) | implementation defined |
| execution_wide_character_encoding | Type alias for the encoding of wide string literals (C++11 2.3p3) | implementation defined |
| char8_character_encoding | Type alias for the encoding of UTF-8 string literals (C++11 2.14.5p7) | implementation defined |
| char16_character_encoding | Type alias for the encoding of char16_t string literals (C++11 2.14.5p9) | implementation defined |
| char32_character_encoding | Type alias for the encoding of char32_t string literals (C++11 2.14.5p10) | implementation defined |
| basic_execution_character_encoding | An encoding that meets the minimum requirements of C++11 2.3p3 | trivial |
| basic_execution_wide_character_encoding | An encoding that meets the minimum requirements of C++11 2.3p3 | trivial |
| iso_10646_wide_character_encoding | An ISO 10646 encoding. Only defined if STDC_ISO_10646 is defined | trivial |
| utf8_encoding | Unicode UTF-8 | stateless, variable width |
| utf8bom_encoding | Unicode UTF-8 with a byte order mark | stateful, variable width |
| utf16_encoding | Unicode UTF-16, native endian | stateless, variable width |
| utf16be_encoding | Unicode UTF-16, big endian | stateless, variable width |
| utf16le_encoding | Unicode UTF-16, little endian | stateless, variable width |
| utf16bom_encoding | Unicode UTF-16 with a byte order mark | stateful, variable width |
| utf32_encoding | Unicode UTF-32, native endian | trivial |
| utf32be_encoding | Unicode UTF-32, big endian | stateless, fixed width |
| utf32le_encoding | Unicode UTF-32, little endian | stateless, fixed width |
| utf32bom_encoding | Unicode UTF-32 with a byte order mark | stateful, variable width |
The terminology used in this document and in the Text_view library has been chosen to be consistent with industry standards and, in particular, the Unicode standard. Any inconsistencies in the use of this terminology and that in the Unicode standard is unintentional. The terms described in this document and used within the Text_view library comprise a subset of the terminology used within the Unicode standard; only those terms necessary to specify functionality exhibited by this library are included here. Those who would like to learn more about general text processing terminology in computer systems are encouraged to read chatper 2, "General Structure" of the Unicode standard.
A single, indivisible, integral element of an encoded sequence of characters. A sequence of one or more code units specifies a code point or encoding state transition as defined by a character encoding. A code unit does not, by itself, identify any particular character or code point; the meaning ascribed to a particular code unit value is derived from a character encoding definition.
The C++11 char, wchar_t, char16_t, and char32_t
types are most commonly used as code unit types.
The string literal u8"J\u00F8erg" contains 7 code units and 6 code unit
sequences; "\u00F8" is encoded using two code units and string literals contain
a trailing NUL code unit.
The string literal "J\u00F8erg" contains an implementation defined number of
code units. The standard does not specify the encoding of ordinary and wide
string literals, so the number of code units encoded by "\u00F8" depends on the
implementation defined encoding used for ordinary string literals.
An integral value denoting an abstract character as defined by a character set. A code point does not, by itself, identify any particular character; the meaning ascribed to a particular code point value is derived from a character set definition.
The C++11 char, wchar_t, char16_t, and char32_t
types are most commonly used as code point types.
The string literal u8"J\u00F8erg" describes a sequence of 6 code point values;
string literals implicitly specify a trailing NUL code point.
The string literal "J\u00F8erg" describes a sequence of an implementation
defined number of code point values. The standard does not specify the encoding
of ordinary and wide string literals, so the number of code points encoded by
"\u00F8" depends on the implementation defined encoding used for ordinary string
literals. Implementations are permitted to translate a single code point in the
source or Unicode character sets to multiple code points in the execution
encoding.
A mapping of code point values to abstract characters. A character set need not provide a mapping for every possible code point value representable by the code point type.
C++11 does not specify the use of any particular character set or encoding for ordinary and wide character and string literals, though it does place some restrictions on them. Unicode character and string literals are governed by the Unicode standard.
Common character sets include ASCII, Unicode, and Windows code page 1252.
An element of written language, for example, a letter, number, or symbol. A character is identified by the combination of a character set and a code point value.
A method of representing a sequence of characters as a sequence of code unit sequences.
An encoding may be stateless or stateful. In stateless encodings, characters may be encoded or decoded starting from the beginning of any code unit sequence. In stateful encodings, it may be necessary to record certain affects of previously encoded characters in order to correctly encode additional characters, or to decode preceding code unit sequences in order to correctly decode following code unit sequences.
An encoding may be fixed width or variable width. In fixed width encodings, all characters are encoded using a single code unit sequence and all code unit sequences have the same length. In variable width encodings, different characters may require multiple code unit sequences, or code unit sequences of varying length.
An encoding may support bidirectional or random access decoding of code unit sequences. In bidirectional encodings, characters may be decoded by traversing code unit sequences in reverse order. Such encodings must support a method to identify the start of a preceding code unit sequence. In random access encodings, characters may be decoded from any code unit sequence within the sequence of code unit sequences, in constant time, without having to decode any other code unit sequence. Random access encodings are necessarily stateless and fixed length. An encoding that is neither bidirectional, nor random access, may only be decoded by traversing code unit sequences in forward order.
An encoding may support encoding characters from multiple character sets. Such an encoding is either stateful and defines code unit sequences that switch the active character set, or defines code unit sequences that implicitly identify a character set, or both.
A trivial encoding is one in which all encoded characters correspond to a single character set and where each code unit encodes exactly one character using the same value as the code point for that character. Such an encoding is stateless, fixed width, and supports random access decoding.
Common encodings include the Unicode UTF-8, UTF-16, and UTF-32 encodings, the ISO/IEC 8859 series of encodings including ISO/IEC 8859-1, and many trivial encodings such as Windows code page 1252.
- Text_view
https://github.com/tahonermann/text_view - Text_view-range-v3 https://github.com/tahonermann/text_view-range-v3
- cmcstl2 https://github.com/CaseyCarter/cmcstl2
- ISO/IEC technical specification 19217:2015, C++ Extensions for concepts
http://www.iso.org/iso/home/store/catalogue_tc/catalogue_detail.htm?csnumber=64031 - P0252R0: Operator Dot Wording http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2016/p0252r0.pdf
- P0184R0: Generalizing the Range-Based For Loop
http://open-std.org/JTC1/SC22/WG21/docs/papers/2016/p0184r0.html - P0022R1: Proxy Iterators for the Ranges Extensions
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/p0022r1.html - N4560: Working Draft, C++ Extensions for Ranges
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2015/n4560.pdf - N2442: Raw and Unicode String Literals; Unified Proposal (Rev. 2)
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2442.htm - N2249: New Character Types in C++
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2249.html - Unicode
http://unicode.org - CMake
https://cmake.org