[PATCH v2 2/5] Copy string_view files from libstdc++

[Simon Marchi <simon dot marchi at polymtl dot ca>]

This patch copies the following files from libstdc++ (commit
b427286632d7):

  ${gcc}/include/std/string_view -> ${binutils-gdb}/gdb/common/string_view.h
  ${gcc}/include/bits/string_view.tcc -> ${binutils-gdb}/gdb/common/string_view.tcc

The local modifications are done in the following patch in order to make
it easier to review them.

gdb/ChangeLog:

	* common/string_view.h: New file.
	* common/string_view.tcc: New file.
---
 gdb/common/string_view.h   | 661 +++++++++++++++++++++++++++++++++++++++++++++
 gdb/common/string_view.tcc | 229 ++++++++++++++++
 2 files changed, 890 insertions(+)
 create mode 100644 gdb/common/string_view.h
 create mode 100644 gdb/common/string_view.tcc

diff --git a/gdb/common/string_view.h b/gdb/common/string_view.h
new file mode 100644
index 000000000000..9f39df853e8d
--- /dev/null
+++ b/gdb/common/string_view.h
@@ -0,0 +1,661 @@
+// 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
+      {
+	// TODO: Assert to restore in a way compatible with the constexpr.
+	// __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
+      {
+	// TODO: Assert to restore in a way compatible with the constexpr.
+	// __glibcxx_assert(this->_M_len > 0);
+	return *this->_M_str;
+      }
+
+      constexpr const _CharT&
+      back() const noexcept
+      {
+	// TODO: Assert to restore in a way compatible with the constexpr.
+	// __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);
+	for (auto __begin = this->_M_str + __pos,
+	     __end = __begin + __rlen; __begin != __end;)
+	  *__str++ = *__begin++;
+	return __rlen;
+      }
+
+      constexpr basic_string_view
+      substr(size_type __pos, 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
diff --git a/gdb/common/string_view.tcc b/gdb/common/string_view.tcc
new file mode 100644
index 000000000000..07ccc849dd70
--- /dev/null
+++ b/gdb/common/string_view.tcc
@@ -0,0 +1,229 @@
+// 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 include/bits/string_view.tcc
+ *  This is an internal header file, included by other library headers.
+ *  Do not attempt to use it directly. @headername{string_view}
+ */
+
+//
+// N3762 basic_string_view library
+//
+
+#ifndef _GLIBCXX_STRING_VIEW_TCC
+#define _GLIBCXX_STRING_VIEW_TCC 1
+
+#pragma GCC system_header
+
+#if __cplusplus >= 201703L
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find(const _CharT* __str, size_type __pos, size_type __n) const noexcept
+    {
+      __glibcxx_requires_string_len(__str, __n);
+
+      if (__n == 0)
+	return __pos <= this->_M_len ? __pos : npos;
+
+      if (__n <= this->_M_len)
+	{
+	  for (; __pos <= this->_M_len - __n; ++__pos)
+	    if (traits_type::eq(this->_M_str[__pos], __str[0])
+		&& traits_type::compare(this->_M_str + __pos + 1,
+					__str + 1, __n - 1) == 0)
+	      return __pos;
+	}
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find(_CharT __c, size_type __pos) const noexcept
+    {
+      size_type __ret = npos;
+      if (__pos < this->_M_len)
+	{
+	  const size_type __n = this->_M_len - __pos;
+	  const _CharT* __p = traits_type::find(this->_M_str + __pos, __n, __c);
+	  if (__p)
+	    __ret = __p - this->_M_str;
+	}
+      return __ret;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    rfind(const _CharT* __str, size_type __pos, size_type __n) const noexcept
+    {
+      __glibcxx_requires_string_len(__str, __n);
+
+      if (__n <= this->_M_len)
+	{
+	  __pos = std::min(size_type(this->_M_len - __n), __pos);
+	  do
+	    {
+	      if (traits_type::compare(this->_M_str + __pos, __str, __n) == 0)
+		return __pos;
+	    }
+	  while (__pos-- > 0);
+	}
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    rfind(_CharT __c, size_type __pos) const noexcept
+    {
+      size_type __size = this->_M_len;
+      if (__size > 0)
+	{
+	  if (--__size > __pos)
+	    __size = __pos;
+	  for (++__size; __size-- > 0; )
+	    if (traits_type::eq(this->_M_str[__size], __c))
+	      return __size;
+	}
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find_first_of(const _CharT* __str, size_type __pos,
+		  size_type __n) const noexcept
+    {
+      __glibcxx_requires_string_len(__str, __n);
+      for (; __n && __pos < this->_M_len; ++__pos)
+	{
+	  const _CharT* __p = traits_type::find(__str, __n,
+						this->_M_str[__pos]);
+	  if (__p)
+	    return __pos;
+	}
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find_last_of(const _CharT* __str, size_type __pos,
+		 size_type __n) const noexcept
+    {
+      __glibcxx_requires_string_len(__str, __n);
+      size_type __size = this->size();
+      if (__size && __n)
+	{
+	  if (--__size > __pos)
+	    __size = __pos;
+	  do
+	    {
+	      if (traits_type::find(__str, __n, this->_M_str[__size]))
+		return __size;
+	    }
+	  while (__size-- != 0);
+	}
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find_first_not_of(const _CharT* __str, size_type __pos,
+		      size_type __n) const noexcept
+    {
+      __glibcxx_requires_string_len(__str, __n);
+      for (; __pos < this->_M_len; ++__pos)
+	if (!traits_type::find(__str, __n, this->_M_str[__pos]))
+	  return __pos;
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find_first_not_of(_CharT __c, size_type __pos) const noexcept
+    {
+      for (; __pos < this->_M_len; ++__pos)
+	if (!traits_type::eq(this->_M_str[__pos], __c))
+	  return __pos;
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find_last_not_of(const _CharT* __str, size_type __pos,
+		     size_type __n) const noexcept
+    {
+      __glibcxx_requires_string_len(__str, __n);
+      size_type __size = this->_M_len;
+      if (__size)
+	{
+	  if (--__size > __pos)
+	    __size = __pos;
+	  do
+	    {
+	      if (!traits_type::find(__str, __n, this->_M_str[__size]))
+		return __size;
+	    }
+	  while (__size--);
+	}
+      return npos;
+    }
+
+  template<typename _CharT, typename _Traits>
+    constexpr typename basic_string_view<_CharT, _Traits>::size_type
+    basic_string_view<_CharT, _Traits>::
+    find_last_not_of(_CharT __c, size_type __pos) const noexcept
+    {
+      size_type __size = this->_M_len;
+      if (__size)
+	{
+	  if (--__size > __pos)
+	    __size = __pos;
+	  do
+	    {
+	      if (!traits_type::eq(this->_M_str[__size], __c))
+		return __size;
+	    }
+	  while (__size--);
+	}
+      return npos;
+    }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace std
+
+#endif // __cplusplus <= 201402L
+
+#endif // _GLIBCXX_STRING_VIEW_TCC
-- 
2.16.3