119 lines
1.9 KiB
C++
119 lines
1.9 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#ifndef TEMPLATE_STRING_HXX
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#define TEMPLATE_STRING_HXX
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#include <array> // for std::size()
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#include <cstddef>
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#include <string_view>
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namespace TemplateString {
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template<std::size_t _size>
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struct Buffer {
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static constexpr std::size_t size = _size;
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char value[size + 1];
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constexpr operator const char *() const noexcept {
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return value;
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}
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constexpr operator std::string_view() const noexcept {
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return {value, size};
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}
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};
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/**
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* An empty string.
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*/
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constexpr auto
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Empty() noexcept
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{
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return Buffer<0>{};
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}
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/**
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* A string consisting of a single character.
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*/
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constexpr auto
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FromChar(char ch) noexcept
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{
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Buffer<1> result{};
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result.value[0] = ch;
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return result;
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}
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namespace detail {
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constexpr auto
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size(const char &) noexcept
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{
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return 1;
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}
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constexpr const char *
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data(const char &ch) noexcept
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{
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return &ch;
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}
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template<std::size_t s>
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constexpr auto
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size(const Buffer<s> &b) noexcept
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{
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return b.size;
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}
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template<std::size_t size>
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constexpr const char *
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data(const Buffer<size> &b) noexcept
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{
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return b.value;
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}
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constexpr char *
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copy_n(const char *src, std::size_t n, char *dest) noexcept
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{
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for (std::size_t i = 0; i < n; ++i)
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dest[i] = src[i];
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return dest + n;
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}
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}
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/**
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* A string consisting of a single character.
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*/
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template<std::size_t size>
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constexpr auto
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FromLiteral(const char (&src)[size]) noexcept
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{
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Buffer<size - 1> result{};
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detail::copy_n(src, result.size, result.value);
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return result;
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}
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template<typename... Args>
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constexpr auto
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Concat(Args... args) noexcept
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{
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using std::size;
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using std::data;
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using detail::size;
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using detail::data;
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using detail::copy_n;
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constexpr std::size_t total_size = (std::size_t(0) + ... + size(args));
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Buffer<total_size> result{};
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char *p = result.value;
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((p = copy_n(data(args), size(args), p)), ...);
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return result;
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}
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} // namespace TemplateString
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#endif
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