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// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef _LIBCPP___FORMAT_FORMATTER_H
#define _LIBCPP___FORMAT_FORMATTER_H
#include <__algorithm/copy.h>
#include <__algorithm/fill_n.h>
#include <__availability>
#include <__config>
#include <__format/format_error.h>
#include <__format/format_fwd.h>
#include <__format/format_string.h>
#include <__format/parser_std_format_spec.h>
#include <concepts>
#include <string_view>
#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#pragma GCC system_header
#endif
_LIBCPP_PUSH_MACROS
#include <__undef_macros>
_LIBCPP_BEGIN_NAMESPACE_STD
#if _LIBCPP_STD_VER > 17
// TODO FMT Remove this once we require compilers with proper C++20 support.
// If the compiler has no concepts support, the format header will be disabled.
// Without concepts support enable_if needs to be used and that too much effort
// to support compilers with partial C++20 support.
#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
// Currently not implemented specializations throw an exception when used. This
// does not conform to the Standard. However not all Standard defined formatters
// have been implemented yet. Until that time the current behavior is intended.
// TODO FMT Disable the default template.
template <class _Tp, class _CharT>
struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter {
_LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI auto parse(auto& __parse_ctx)
-> decltype(__parse_ctx.begin()) {
__throw();
}
_LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI auto format(_Tp, auto& __ctx)
-> decltype(__ctx.out()) {
__throw();
}
private:
_LIBCPP_NORETURN _LIBCPP_HIDE_FROM_ABI void __throw() {
__throw_format_error("Argument type not implemented yet");
}
};
namespace __formatter {
/** The character types that formatters are specialized for. */
template <class _CharT>
concept __char_type = same_as<_CharT, char> || same_as<_CharT, wchar_t>;
struct _LIBCPP_TEMPLATE_VIS __padding_size_result {
size_t __before;
size_t __after;
};
_LIBCPP_HIDE_FROM_ABI constexpr __padding_size_result
__padding_size(size_t __size, size_t __width,
__format_spec::_Flags::_Alignment __align) {
_LIBCPP_ASSERT(__width > __size,
"Don't call this function when no padding is required");
_LIBCPP_ASSERT(
__align != __format_spec::_Flags::_Alignment::__default,
"Caller should adjust the default to the value required by the type");
size_t __fill = __width - __size;
switch (__align) {
case __format_spec::_Flags::_Alignment::__default:
_LIBCPP_UNREACHABLE();
case __format_spec::_Flags::_Alignment::__left:
return {0, __fill};
case __format_spec::_Flags::_Alignment::__center: {
// The extra padding is divided per [format.string.std]/3
// __before = floor(__fill, 2);
// __after = ceil(__fill, 2);
size_t __before = __fill / 2;
size_t __after = __fill - __before;
return {__before, __after};
}
case __format_spec::_Flags::_Alignment::__right:
return {__fill, 0};
}
_LIBCPP_UNREACHABLE();
}
/**
* Writes the input to the output with the required padding.
*
* Since the output column width is specified the function can be used for
* ASCII and Unicode input.
*
* @pre [@a __first, @a __last) is a valid range.
* @pre @a __size <= @a __width. Using this function when this pre-condition
* doesn't hold incurs an unwanted overhead.
*
* @param __out_it The output iterator to write to.
* @param __first Pointer to the first element to write.
* @param __last Pointer beyond the last element to write.
* @param __size The (estimated) output column width. When the elements
* to be written are ASCII the following condition holds
* @a __size == @a __last - @a __first.
* @param __width The number of output columns to write.
* @param __fill The character used for the alignment of the output.
* TODO FMT Will probably change to support Unicode grapheme
* cluster.
* @param __alignment The requested alignment.
*
* @returns An iterator pointing beyond the last element written.
*
* @note The type of the elements in range [@a __first, @a __last) can differ
* from the type of @a __fill. Integer output uses @c std::to_chars for its
* conversion, which means the [@a __first, @a __last) always contains elements
* of the type @c char.
*/
template <class _CharT, class _Fill>
_LIBCPP_HIDE_FROM_ABI auto
__write(output_iterator<const _CharT&> auto __out_it, const _CharT* __first,
const _CharT* __last, size_t __size, size_t __width, _Fill __fill,
__format_spec::_Flags::_Alignment __alignment) -> decltype(__out_it) {
_LIBCPP_ASSERT(__first <= __last, "Not a valid range");
_LIBCPP_ASSERT(__size < __width, "Precondition failure");
__padding_size_result __padding =
__padding_size(__size, __width, __alignment);
__out_it = _VSTD::fill_n(_VSTD::move(__out_it), __padding.__before, __fill);
__out_it = _VSTD::copy(__first, __last, _VSTD::move(__out_it));
return _VSTD::fill_n(_VSTD::move(__out_it), __padding.__after, __fill);
}
/**
* @overload
*
* Uses a transformation operation before writing an element.
*
* TODO FMT Fill will probably change to support Unicode grapheme cluster.
*/
template <class _CharT, class _UnaryOperation, class _Fill>
_LIBCPP_HIDE_FROM_ABI auto
__write(output_iterator<const _CharT&> auto __out_it, const _CharT* __first,
const _CharT* __last, size_t __size, _UnaryOperation __op,
size_t __width, _Fill __fill,
__format_spec::_Flags::_Alignment __alignment) -> decltype(__out_it) {
_LIBCPP_ASSERT(__first <= __last, "Not a valid range");
_LIBCPP_ASSERT(__size < __width, "Precondition failure");
__padding_size_result __padding =
__padding_size(__size, __width, __alignment);
__out_it = _VSTD::fill_n(_VSTD::move(__out_it), __padding.__before, __fill);
__out_it = _VSTD::transform(__first, __last, _VSTD::move(__out_it), __op);
return _VSTD::fill_n(_VSTD::move(__out_it), __padding.__after, __fill);
}
/**
* Writes Unicode input to the output with the required padding.
*
* This function does almost the same as the @ref __write function, but handles
* the width estimation of the Unicode input.
*
* @param __str The range [@a __first, @a __last).
* @param __precision The width to truncate the input string to, use @c -1 for
* no limit.
*/
template <class _CharT, class _Fill>
_LIBCPP_HIDE_FROM_ABI auto
__write_unicode(output_iterator<const _CharT&> auto __out_it,
basic_string_view<_CharT> __str, ptrdiff_t __width,
ptrdiff_t __precision, _Fill __fill,
__format_spec::_Flags::_Alignment __alignment)
-> decltype(__out_it) {
// This value changes when there Unicode column width limits the output
// size.
auto __last = __str.end();
if (__width != 0 || __precision != -1) {
__format_spec::__string_alignment<_CharT> __format_traits =
__format_spec::__get_string_alignment(__str.begin(), __str.end(),
__width, __precision);
if (__format_traits.__align)
return __write(_VSTD::move(__out_it), __str.begin(),
__format_traits.__last, __format_traits.__size, __width,
__fill, __alignment);
// No alignment required update the output based on the precision.
// This might be the same as __str.end().
__last = __format_traits.__last;
}
// Copy the input to the output. The output size might be limited by the
// precision.
return _VSTD::copy(__str.begin(), __last, _VSTD::move(__out_it));
}
} // namespace __formatter
#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
#endif //_LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
#endif // _LIBCPP___FORMAT_FORMATTER_H
|
