Edit: string_view
// Components for manipulating non-owning sequences of characters -*- C++ -*- // Copyright (C) 2013-2018 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This library is distributed in the hope that it will be useful, // but WITHOUT ANY WARRANTY; without even the implied warranty of // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // GNU General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. /** @file string_view * This is a Standard C++ Library header. */ // // N3762 basic_string_view library // #ifndef _GLIBCXX_STRING_VIEW #define _GLIBCXX_STRING_VIEW 1 #pragma GCC system_header #if __cplusplus >= 201703L #include <limits> #include <iosfwd> #include <bits/char_traits.h> #include <bits/functional_hash.h> #include <bits/range_access.h> namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION #define __cpp_lib_string_view 201603 /** * @class basic_string_view <string_view> * @brief A non-owning reference to a string. * * @ingroup strings * @ingroup sequences * * @tparam _CharT Type of character * @tparam _Traits Traits for character type, defaults to * char_traits<_CharT>. * * A basic_string_view looks like this: * * @code * _CharT* _M_str * size_t _M_len * @endcode */ template<typename _CharT, typename _Traits = std::char_traits<_CharT>> class basic_string_view { public: // types using traits_type = _Traits; using value_type = _CharT; using pointer = const _CharT*; using const_pointer = const _CharT*; using reference = const _CharT&; using const_reference = const _CharT&; using const_iterator = const _CharT*; using iterator = const_iterator; using const_reverse_iterator = std::reverse_iterator<const_iterator>; using reverse_iterator = const_reverse_iterator; using size_type = size_t; using difference_type = ptrdiff_t; static constexpr size_type npos = size_type(-1); // [string.view.cons], construct/copy constexpr basic_string_view() noexcept : _M_len{0}, _M_str{nullptr} { } constexpr basic_string_view(const basic_string_view&) noexcept = default; constexpr basic_string_view(const _CharT* __str) noexcept : _M_len{__str == nullptr ? 0 : traits_type::length(__str)}, _M_str{__str} { } constexpr basic_string_view(const _CharT* __str, size_type __len) noexcept : _M_len{__len}, _M_str{__str} { } constexpr basic_string_view& operator=(const basic_string_view&) noexcept = default; // [string.view.iterators], iterators constexpr const_iterator begin() const noexcept { return this->_M_str; } constexpr const_iterator end() const noexcept { return this->_M_str + this->_M_len; } constexpr const_iterator cbegin() const noexcept { return this->_M_str; } constexpr const_iterator cend() const noexcept { return this->_M_str + this->_M_len; } constexpr const_reverse_iterator rbegin() const noexcept { return const_reverse_iterator(this->end()); } constexpr const_reverse_iterator rend() const noexcept { return const_reverse_iterator(this->begin()); } constexpr const_reverse_iterator crbegin() const noexcept { return const_reverse_iterator(this->end()); } constexpr const_reverse_iterator crend() const noexcept { return const_reverse_iterator(this->begin()); } // [string.view.capacity], capacity constexpr size_type size() const noexcept { return this->_M_len; } constexpr size_type length() const noexcept { return _M_len; } constexpr size_type max_size() const noexcept { return (npos - sizeof(size_type) - sizeof(void*)) / sizeof(value_type) / 4; } [[nodiscard]] constexpr bool empty() const noexcept { return this->_M_len == 0; } // [string.view.access], element access constexpr const _CharT& operator[](size_type __pos) const noexcept { __glibcxx_assert(__pos < this->_M_len); return *(this->_M_str + __pos); } constexpr const _CharT& at(size_type __pos) const { if (__pos >= _M_len) __throw_out_of_range_fmt(__N("basic_string_view::at: __pos " "(which is %zu) >= this->size() " "(which is %zu)"), __pos, this->size()); return *(this->_M_str + __pos); } constexpr const _CharT& front() const noexcept { __glibcxx_assert(this->_M_len > 0); return *this->_M_str; } constexpr const _CharT& back() const noexcept { __glibcxx_assert(this->_M_len > 0); return *(this->_M_str + this->_M_len - 1); } constexpr const _CharT* data() const noexcept { return this->_M_str; } // [string.view.modifiers], modifiers: constexpr void remove_prefix(size_type __n) noexcept { __glibcxx_assert(this->_M_len >= __n); this->_M_str += __n; this->_M_len -= __n; } constexpr void remove_suffix(size_type __n) noexcept { this->_M_len -= __n; } constexpr void swap(basic_string_view& __sv) noexcept { auto __tmp = *this; *this = __sv; __sv = __tmp; } // [string.view.ops], string operations: size_type copy(_CharT* __str, size_type __n, size_type __pos = 0) const { __glibcxx_requires_string_len(__str, __n); __pos = _M_check(__pos, "basic_string_view::copy"); const size_type __rlen = std::min(__n, _M_len - __pos); // _GLIBCXX_RESOLVE_LIB_DEFECTS // 2777. basic_string_view::copy should use char_traits::copy traits_type::copy(__str, data() + __pos, __rlen); return __rlen; } constexpr basic_string_view substr(size_type __pos = 0, size_type __n = npos) const noexcept(false) { __pos = _M_check(__pos, "basic_string_view::substr"); const size_type __rlen = std::min(__n, _M_len - __pos); return basic_string_view{_M_str + __pos, __rlen}; } constexpr int compare(basic_string_view __str) const noexcept { const size_type __rlen = std::min(this->_M_len, __str._M_len); int __ret = traits_type::compare(this->_M_str, __str._M_str, __rlen); if (__ret == 0) __ret = _S_compare(this->_M_len, __str._M_len); return __ret; } constexpr int compare(size_type __pos1, size_type __n1, basic_string_view __str) const { return this->substr(__pos1, __n1).compare(__str); } constexpr int compare(size_type __pos1, size_type __n1, basic_string_view __str, size_type __pos2, size_type __n2) const { return this->substr(__pos1, __n1).compare(__str.substr(__pos2, __n2)); } constexpr int compare(const _CharT* __str) const noexcept { return this->compare(basic_string_view{__str}); } constexpr int compare(size_type __pos1, size_type __n1, const _CharT* __str) const { return this->substr(__pos1, __n1).compare(basic_string_view{__str}); } constexpr int compare(size_type __pos1, size_type __n1, const _CharT* __str, size_type __n2) const noexcept(false) { return this->substr(__pos1, __n1) .compare(basic_string_view(__str, __n2)); } constexpr size_type find(basic_string_view __str, size_type __pos = 0) const noexcept { return this->find(__str._M_str, __pos, __str._M_len); } constexpr size_type find(_CharT __c, size_type __pos = 0) const noexcept; constexpr size_type find(const _CharT* __str, size_type __pos, size_type __n) const noexcept; constexpr size_type find(const _CharT* __str, size_type __pos = 0) const noexcept { return this->find(__str, __pos, traits_type::length(__str)); } constexpr size_type rfind(basic_string_view __str, size_type __pos = npos) const noexcept { return this->rfind(__str._M_str, __pos, __str._M_len); } constexpr size_type rfind(_CharT __c, size_type __pos = npos) const noexcept; constexpr size_type rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept; constexpr size_type rfind(const _CharT* __str, size_type __pos = npos) const noexcept { return this->rfind(__str, __pos, traits_type::length(__str)); } constexpr size_type find_first_of(basic_string_view __str, size_type __pos = 0) const noexcept { return this->find_first_of(__str._M_str, __pos, __str._M_len); } constexpr size_type find_first_of(_CharT __c, size_type __pos = 0) const noexcept { return this->find(__c, __pos); } constexpr size_type find_first_of(const _CharT* __str, size_type __pos, size_type __n) const noexcept; constexpr size_type find_first_of(const _CharT* __str, size_type __pos = 0) const noexcept { return this->find_first_of(__str, __pos, traits_type::length(__str)); } constexpr size_type find_last_of(basic_string_view __str, size_type __pos = npos) const noexcept { return this->find_last_of(__str._M_str, __pos, __str._M_len); } constexpr size_type find_last_of(_CharT __c, size_type __pos=npos) const noexcept { return this->rfind(__c, __pos); } constexpr size_type find_last_of(const _CharT* __str, size_type __pos, size_type __n) const noexcept; constexpr size_type find_last_of(const _CharT* __str, size_type __pos = npos) const noexcept { return this->find_last_of(__str, __pos, traits_type::length(__str)); } constexpr size_type find_first_not_of(basic_string_view __str, size_type __pos = 0) const noexcept { return this->find_first_not_of(__str._M_str, __pos, __str._M_len); } constexpr size_type find_first_not_of(_CharT __c, size_type __pos = 0) const noexcept; constexpr size_type find_first_not_of(const _CharT* __str, size_type __pos, size_type __n) const noexcept; constexpr size_type find_first_not_of(const _CharT* __str, size_type __pos = 0) const noexcept { return this->find_first_not_of(__str, __pos, traits_type::length(__str)); } constexpr size_type find_last_not_of(basic_string_view __str, size_type __pos = npos) const noexcept { return this->find_last_not_of(__str._M_str, __pos, __str._M_len); } constexpr size_type find_last_not_of(_CharT __c, size_type __pos = npos) const noexcept; constexpr size_type find_last_not_of(const _CharT* __str, size_type __pos, size_type __n) const noexcept; constexpr size_type find_last_not_of(const _CharT* __str, size_type __pos = npos) const noexcept { return this->find_last_not_of(__str, __pos, traits_type::length(__str)); } constexpr size_type _M_check(size_type __pos, const char* __s) const noexcept(false) { if (__pos > this->size()) __throw_out_of_range_fmt(__N("%s: __pos (which is %zu) > " "this->size() (which is %zu)"), __s, __pos, this->size()); return __pos; } // NB: _M_limit doesn't check for a bad __pos value. constexpr size_type _M_limit(size_type __pos, size_type __off) const noexcept { const bool __testoff = __off < this->size() - __pos; return __testoff ? __off : this->size() - __pos; } private: static constexpr int _S_compare(size_type __n1, size_type __n2) noexcept { const difference_type __diff = __n1 - __n2; if (__diff > std::numeric_limits<int>::max()) return std::numeric_limits<int>::max(); if (__diff < std::numeric_limits<int>::min()) return std::numeric_limits<int>::min(); return static_cast<int>(__diff); } size_t _M_len; const _CharT* _M_str; }; // [string.view.comparison], non-member basic_string_view comparison function namespace __detail { // Identity transform to create a non-deduced context, so that only one // argument participates in template argument deduction and the other // argument gets implicitly converted to the deduced type. See n3766.html. template<typename _Tp> using __idt = common_type_t<_Tp>; } template<typename _CharT, typename _Traits> constexpr bool operator==(basic_string_view<_CharT, _Traits> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.size() == __y.size() && __x.compare(__y) == 0; } template<typename _CharT, typename _Traits> constexpr bool operator==(basic_string_view<_CharT, _Traits> __x, __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept { return __x.size() == __y.size() && __x.compare(__y) == 0; } template<typename _CharT, typename _Traits> constexpr bool operator==(__detail::__idt<basic_string_view<_CharT, _Traits>> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.size() == __y.size() && __x.compare(__y) == 0; } template<typename _CharT, typename _Traits> constexpr bool operator!=(basic_string_view<_CharT, _Traits> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return !(__x == __y); } template<typename _CharT, typename _Traits> constexpr bool operator!=(basic_string_view<_CharT, _Traits> __x, __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept { return !(__x == __y); } template<typename _CharT, typename _Traits> constexpr bool operator!=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return !(__x == __y); } template<typename _CharT, typename _Traits> constexpr bool operator< (basic_string_view<_CharT, _Traits> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) < 0; } template<typename _CharT, typename _Traits> constexpr bool operator< (basic_string_view<_CharT, _Traits> __x, __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept { return __x.compare(__y) < 0; } template<typename _CharT, typename _Traits> constexpr bool operator< (__detail::__idt<basic_string_view<_CharT, _Traits>> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) < 0; } template<typename _CharT, typename _Traits> constexpr bool operator> (basic_string_view<_CharT, _Traits> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) > 0; } template<typename _CharT, typename _Traits> constexpr bool operator> (basic_string_view<_CharT, _Traits> __x, __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept { return __x.compare(__y) > 0; } template<typename _CharT, typename _Traits> constexpr bool operator> (__detail::__idt<basic_string_view<_CharT, _Traits>> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) > 0; } template<typename _CharT, typename _Traits> constexpr bool operator<=(basic_string_view<_CharT, _Traits> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) <= 0; } template<typename _CharT, typename _Traits> constexpr bool operator<=(basic_string_view<_CharT, _Traits> __x, __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept { return __x.compare(__y) <= 0; } template<typename _CharT, typename _Traits> constexpr bool operator<=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) <= 0; } template<typename _CharT, typename _Traits> constexpr bool operator>=(basic_string_view<_CharT, _Traits> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) >= 0; } template<typename _CharT, typename _Traits> constexpr bool operator>=(basic_string_view<_CharT, _Traits> __x, __detail::__idt<basic_string_view<_CharT, _Traits>> __y) noexcept { return __x.compare(__y) >= 0; } template<typename _CharT, typename _Traits> constexpr bool operator>=(__detail::__idt<basic_string_view<_CharT, _Traits>> __x, basic_string_view<_CharT, _Traits> __y) noexcept { return __x.compare(__y) >= 0; } // [string.view.io], Inserters and extractors template<typename _CharT, typename _Traits> inline basic_ostream<_CharT, _Traits>& operator<<(basic_ostream<_CharT, _Traits>& __os, basic_string_view<_CharT,_Traits> __str) { return __ostream_insert(__os, __str.data(), __str.size()); } // basic_string_view typedef names using string_view = basic_string_view<char>; #ifdef _GLIBCXX_USE_WCHAR_T using wstring_view = basic_string_view<wchar_t>; #endif #ifdef _GLIBCXX_USE_C99_STDINT_TR1 using u16string_view = basic_string_view<char16_t>; using u32string_view = basic_string_view<char32_t>; #endif // [string.view.hash], hash support: template<typename _Tp> struct hash; template<> struct hash<string_view> : public __hash_base<size_t, string_view> { size_t operator()(const string_view& __str) const noexcept { return std::_Hash_impl::hash(__str.data(), __str.length()); } }; template<> struct __is_fast_hash<hash<string_view>> : std::false_type { }; #ifdef _GLIBCXX_USE_WCHAR_T template<> struct hash<wstring_view> : public __hash_base<size_t, wstring> { size_t operator()(const wstring_view& __s) const noexcept { return std::_Hash_impl::hash(__s.data(), __s.length() * sizeof(wchar_t)); } }; template<> struct __is_fast_hash<hash<wstring_view>> : std::false_type { }; #endif #ifdef _GLIBCXX_USE_C99_STDINT_TR1 template<> struct hash<u16string_view> : public __hash_base<size_t, u16string_view> { size_t operator()(const u16string_view& __s) const noexcept { return std::_Hash_impl::hash(__s.data(), __s.length() * sizeof(char16_t)); } }; template<> struct __is_fast_hash<hash<u16string_view>> : std::false_type { }; template<> struct hash<u32string_view> : public __hash_base<size_t, u32string_view> { size_t operator()(const u32string_view& __s) const noexcept { return std::_Hash_impl::hash(__s.data(), __s.length() * sizeof(char32_t)); } }; template<> struct __is_fast_hash<hash<u32string_view>> : std::false_type { }; #endif inline namespace literals { inline namespace string_view_literals { #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wliteral-suffix" inline constexpr basic_string_view<char> operator""sv(const char* __str, size_t __len) noexcept { return basic_string_view<char>{__str, __len}; } #ifdef _GLIBCXX_USE_WCHAR_T inline constexpr basic_string_view<wchar_t> operator""sv(const wchar_t* __str, size_t __len) noexcept { return basic_string_view<wchar_t>{__str, __len}; } #endif #ifdef _GLIBCXX_USE_C99_STDINT_TR1 inline constexpr basic_string_view<char16_t> operator""sv(const char16_t* __str, size_t __len) noexcept { return basic_string_view<char16_t>{__str, __len}; } inline constexpr basic_string_view<char32_t> operator""sv(const char32_t* __str, size_t __len) noexcept { return basic_string_view<char32_t>{__str, __len}; } #endif #pragma GCC diagnostic pop } // namespace string_literals } // namespace literals _GLIBCXX_END_NAMESPACE_VERSION } // namespace std #include <bits/string_view.tcc> #endif // __cplusplus <= 201402L #endif // _GLIBCXX_EXPERIMENTAL_STRING_VIEW
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