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// Copyright 2017 Elias Kosunen
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// This file is a part of scnlib:
// https://github.com/eliaskosunen/scnlib
//
// The contents of this file are based on utfcpp:
// https://github.com/nemtrif/utfcpp
// Copyright (c) 2006 Nemanja Trifunovic
// Distributed under the Boost Software License, version 1.0
#ifndef SCN_UNICODE_UNICODE_H
#define SCN_UNICODE_UNICODE_H
#include "utf16.h"
#include "utf8.h"
namespace scn {
SCN_BEGIN_NAMESPACE
namespace detail {
inline constexpr bool is_wide_multichar()
{
return sizeof(wchar_t) == 2;
}
inline constexpr bool is_multichar_type(char)
{
return true;
}
inline constexpr bool is_multichar_type(wchar_t)
{
return is_wide_multichar();
}
using utf8_tag = std::integral_constant<size_t, 1>;
using utf16_tag = std::integral_constant<size_t, 2>;
using utf32_tag = std::integral_constant<size_t, 4>;
#define SCN_MAKE_UTF_TAG(CharT) \
std::integral_constant<size_t, sizeof(CharT)> {}
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> parse_code_point(I begin,
S end,
code_point& cp,
utf8_tag)
{
return utf8::parse_code_point(begin, end, cp);
}
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> parse_code_point(I begin,
S end,
code_point& cp,
utf16_tag)
{
return utf16::parse_code_point(begin, end, cp);
}
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> parse_code_point(I begin,
S end,
code_point& cp,
utf32_tag)
{
SCN_EXPECT(begin != end);
cp = make_code_point(*begin);
return {++begin};
}
} // namespace detail
/**
* Parses a Unicode code point from the range at `[begin, end)`, and writes
* it into `cp`.
*
* The encoding is determined by the size of the value type of the range.
* Let `n = sizeof(typename std::iterator_traits<I>::value_type)`.
* If `n == 1` -> UTF-8. If `n == 2` -> UTF-16. If `n == 4` -> UTF-32.
*
* `begin != end` must be `true`.
*
* On error, `cp` is not written into.
*
* \return On success, returns an iterator one-past the last code unit used
* to parse `cp`. If the code point is encoded incorrectly, returns
* `error::invalid_encoding`.
*/
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> parse_code_point(I begin, S end, code_point& cp)
{
return detail::parse_code_point(
begin, end, cp,
SCN_MAKE_UTF_TAG(typename std::iterator_traits<I>::value_type));
}
namespace detail {
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> encode_code_point(I begin,
S end,
code_point cp,
utf8_tag)
{
return utf8::encode_code_point(begin, end, cp);
}
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> encode_code_point(I begin,
S end,
code_point cp,
utf16_tag)
{
return utf16::encode_code_point(begin, end, cp);
}
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> encode_code_point(I begin,
S end,
code_point cp,
utf32_tag)
{
SCN_EXPECT(begin + 1 >= end);
*begin++ = static_cast<uint32_t>(cp);
return {begin};
}
} // namespace detail
/**
* Writes the code point `cp` into `begin`, using the encoding determined by
* the type of `begin`.
*
* For more information on how the encoding is determined, see \ref
* parse_code_point().
*
* `end` must be reachable from `begin`, and must have enough room to encode
* the code point (4 code units for UTF-8, 2 for UTF-16, and 1 for UTF-32).
*
* \param begin Beginning of the range to write the result to
* \param end End of the range to write the result to
* \param cp Code point to encode
* \return On success, one-past the last code unit written.
* If `cp` was not a valid code point, returns `error::invalid_encoding`.
*/
template <typename I, typename S>
SCN_CONSTEXPR14 expected<I> encode_code_point(I begin, S end, code_point cp)
{
return detail::encode_code_point(
begin, end, cp,
SCN_MAKE_UTF_TAG(typename std::iterator_traits<I>::value_type));
}
namespace detail {
template <typename T>
SCN_CONSTEXPR14 int get_sequence_length(T a, utf8_tag)
{
return utf8::get_sequence_length(a);
}
template <typename T>
SCN_CONSTEXPR14 int get_sequence_length(T a, utf16_tag)
{
return utf16::get_sequence_length(a);
}
template <typename T>
SCN_CONSTEXPR14 int get_sequence_length(T, utf32_tag)
{
return 1;
}
} // namespace detail
/**
* Returns the length of the code point starting from code unit `a` in code
* units.
*
* For information on how the encoding is determined, see \ref
* parse_code_point().
*
* \param a The first code unit in a code point.
*
* \return Length of the code point starting from `a`, in code units
* If the code point is encoded incorrectly, or this code unit is not the
* first code unit in a code point, returns 0.
*/
template <typename T>
SCN_CONSTEXPR14 int get_sequence_length(T a)
{
return detail::get_sequence_length(a, SCN_MAKE_UTF_TAG(T));
}
namespace detail {
template <typename I, typename S>
SCN_CONSTEXPR14 expected<std::ptrdiff_t> code_point_distance(I begin,
S end,
utf8_tag)
{
return utf8::code_point_distance(begin, end);
}
template <typename I, typename S>
SCN_CONSTEXPR14 expected<std::ptrdiff_t> code_point_distance(I begin,
S end,
utf16_tag)
{
return utf16::code_point_distance(begin, end);
}
template <typename I, typename S>
SCN_CONSTEXPR14 expected<std::ptrdiff_t> code_point_distance(I begin,
S end,
utf32_tag)
{
return {end - begin};
}
} // namespace detail
/**
* Get the distance between two code points, in code points.
*
* `end >= begin` must be `true`.
* `begin` and `end` must both point to the first code units in a code
* point.
*
* \return The distance between `begin` and `end`, in code points. If the
* string was encoded incorrectly, returns `error::invalid_encoding`.
*/
template <typename I, typename S>
SCN_CONSTEXPR14 expected<std::ptrdiff_t> code_point_distance(I begin, S end)
{
return detail::code_point_distance(
begin, end,
SCN_MAKE_UTF_TAG(typename std::iterator_traits<I>::value_type));
}
#undef SCN_MAKE_UTF_TAG
SCN_END_NAMESPACE
} // namespace scn
#endif
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