diff --git a/include/string_view b/include/string_view
new file mode 100644
index 0000000..71a6e81
--- /dev/null
+++ b/include/string_view
@@ -0,0 +1,764 @@
+// -*- C++ -*-
+//===------------------------ string_view ---------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_STRING_VIEW
+#define _LIBCPP_STRING_VIEW
+
+/*
+string_view synopsis
+
+namespace std {
+
+    // 7.2, Class template basic_string_view
+    template<class charT, class traits = char_traits<charT>>
+        class basic_string_view;
+
+    // 7.9, basic_string_view non-member comparison functions
+    template<class charT, class traits>
+    constexpr bool operator==(basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator!=(basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator< (basic_string_view<charT, traits> x,
+                                 basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator> (basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator<=(basic_string_view<charT, traits> x,
+                                 basic_string_view<charT, traits> y) noexcept;
+    template<class charT, class traits>
+    constexpr bool operator>=(basic_string_view<charT, traits> x,
+                              basic_string_view<charT, traits> y) noexcept;
+    // see below, sufficient additional overloads of comparison functions
+
+    // 7.10, Inserters and extractors
+    template<class charT, class traits>
+      basic_ostream<charT, traits>&
+        operator<<(basic_ostream<charT, traits>& os,
+                   basic_string_view<charT, traits> str);
+
+    // basic_string_view typedef names
+    typedef basic_string_view<char> string_view;
+    typedef basic_string_view<char16_t> u16string_view;
+    typedef basic_string_view<char32_t> u32string_view;
+    typedef basic_string_view<wchar_t> wstring_view;
+
+    template<class charT, class traits = char_traits<charT>>
+    class basic_string_view {
+      public:
+      // types
+      typedef traits traits_type;
+      typedef charT value_type;
+      typedef charT* pointer;
+      typedef const charT* const_pointer;
+      typedef charT& reference;
+      typedef const charT& const_reference;
+      typedef implementation-defined const_iterator;
+      typedef const_iterator iterator;
+      typedef reverse_iterator<const_iterator> const_reverse_iterator;
+      typedef const_reverse_iterator reverse_iterator;
+      typedef size_t size_type;
+      typedef ptrdiff_t difference_type;
+      static constexpr size_type npos = size_type(-1);
+
+      // 7.3, basic_string_view constructors and assignment operators
+      constexpr basic_string_view() noexcept;
+      constexpr basic_string_view(const basic_string_view&) noexcept = default;
+      basic_string_view& operator=(const basic_string_view&) noexcept = default;
+      template<class Allocator>
+      constexpr basic_string_view(const charT* str);
+      constexpr basic_string_view(const charT* str, size_type len);
+
+      // 7.4, basic_string_view iterator support
+      constexpr const_iterator begin() const noexcept;
+      constexpr const_iterator end() const noexcept;
+      constexpr const_iterator cbegin() const noexcept;
+      constexpr const_iterator cend() const noexcept;
+      const_reverse_iterator rbegin() const noexcept;
+      const_reverse_iterator rend() const noexcept;
+      const_reverse_iterator crbegin() const noexcept;
+      const_reverse_iterator crend() const noexcept;
+
+      // 7.5, basic_string_view capacity
+      constexpr size_type size() const noexcept;
+      constexpr size_type length() const noexcept;
+      constexpr size_type max_size() const noexcept;
+      constexpr bool empty() const noexcept;
+
+      // 7.6, basic_string_view element access
+      constexpr const_reference operator[](size_type pos) const;
+      constexpr const_reference at(size_type pos) const;
+      constexpr const_reference front() const;
+      constexpr const_reference back() const;
+      constexpr const_pointer data() const noexcept;
+
+      // 7.7, basic_string_view modifiers
+      constexpr void clear() noexcept;
+      constexpr void remove_prefix(size_type n);
+      constexpr void remove_suffix(size_type n);
+      constexpr void swap(basic_string_view& s) noexcept;
+
+      size_type copy(charT* s, size_type n, size_type pos = 0) const;
+
+      constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
+      constexpr int compare(basic_string_view s) const noexcept;
+      constexpr int compare(size_type pos1, size_type n1, basic_string_view s) const;
+      constexpr int compare(size_type pos1, size_type n1,
+                            basic_string_view s, size_type pos2, size_type n2) const;
+      constexpr int compare(const charT* s) const;
+      constexpr int compare(size_type pos1, size_type n1, const charT* s) const;
+      constexpr int compare(size_type pos1, size_type n1,
+                            const charT* s, size_type n2) const;
+      constexpr size_type find(basic_string_view s, size_type pos = 0) const noexcept;
+      constexpr size_type find(charT c, size_type pos = 0) const noexcept;
+      constexpr size_type find(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find(const charT* s, size_type pos = 0) const;
+      constexpr size_type rfind(basic_string_view s, size_type pos = npos) const noexcept;
+      constexpr size_type rfind(charT c, size_type pos = npos) const noexcept;
+      constexpr size_type rfind(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type rfind(const charT* s, size_type pos = npos) const;
+      constexpr size_type find_first_of(basic_string_view s, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_of(charT c, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_first_of(const charT* s, size_type pos = 0) const;
+      constexpr size_type find_last_of(basic_string_view s, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_of(charT c, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_last_of(const charT* s, size_type pos = npos) const;
+      constexpr size_type find_first_not_of(basic_string_view s, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_not_of(charT c, size_type pos = 0) const noexcept;
+      constexpr size_type find_first_not_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_first_not_of(const charT* s, size_type pos = 0) const;
+      constexpr size_type find_last_not_of(basic_string_view s, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_not_of(charT c, size_type pos = npos) const noexcept;
+      constexpr size_type find_last_not_of(const charT* s, size_type pos, size_type n) const;
+      constexpr size_type find_last_not_of(const charT* s, size_type pos = npos) const;
+
+     private:
+      const_pointer data_;  // exposition only
+      size_type     size_;  // exposition only
+    };
+
+  // 7.11, Hash support
+  template <class T> struct hash;
+  template <> struct hash<string_view>;
+  template <> struct hash<u16string_view>;
+  template <> struct hash<u32string_view>;
+  template <> struct hash<wstring_view>;
+
+}  // namespace std
+
+
+*/
+
+#include <__config>
+
+#include <__string>
+#include <algorithm>
+#include <iterator>
+#include <__debug>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template<class _CharT, class _Traits = char_traits<_CharT> >
+class _LIBCPP_TYPE_VIS_ONLY basic_string_view {
+public:
+	// types
+	typedef _Traits                                    traits_type;
+	typedef _CharT                                     value_type;
+	typedef const _CharT*                              pointer;
+	typedef const _CharT*                              const_pointer;
+	typedef const _CharT&                              reference;
+	typedef const _CharT&                              const_reference;
+	typedef const_pointer                              const_iterator; // See [string.view.iterators]
+	typedef const_iterator                             iterator;
+	typedef _VSTD::reverse_iterator<const_iterator>    const_reverse_iterator;
+	typedef const_reverse_iterator                     reverse_iterator;
+	typedef size_t                                     size_type;
+	typedef ptrdiff_t                                  difference_type;
+	static _LIBCPP_CONSTEXPR const size_type npos = -1; // size_type(-1);
+
+	// [string.view.cons], construct/copy
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	basic_string_view() _NOEXCEPT : __data (nullptr), __size(0) {}
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	basic_string_view(const basic_string_view&) _NOEXCEPT = default;
+
+	_LIBCPP_INLINE_VISIBILITY
+	basic_string_view& operator=(const basic_string_view&) _NOEXCEPT = default;
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	basic_string_view(const _CharT* __s, size_type __len)
+		: __data(__s), __size(__len)
+	{
+#if _LIBCPP_STD_VER > 11
+        _LIBCPP_ASSERT(__len == 0 || __s != nullptr, "string_view::string_view(_CharT *, size_t): received nullptr");
+#endif
+	}
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	basic_string_view(const _CharT* __s)
+		: __data(__s), __size(_Traits::length(__s)) {}
+
+	// [string.view.iterators], iterators
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_iterator begin()  const _NOEXCEPT { return cbegin(); }
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_iterator end()    const _NOEXCEPT { return cend(); }
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_iterator cbegin() const _NOEXCEPT { return __data; }
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_iterator cend()   const _NOEXCEPT { return __data + __size; }
+
+	_LIBCPP_INLINE_VISIBILITY
+	const_reverse_iterator rbegin()   const _NOEXCEPT { return const_reverse_iterator(cend()); }
+
+	_LIBCPP_INLINE_VISIBILITY
+	const_reverse_iterator rend()     const _NOEXCEPT { return const_reverse_iterator(cbegin()); }
+
+	_LIBCPP_INLINE_VISIBILITY
+	const_reverse_iterator crbegin()  const _NOEXCEPT { return const_reverse_iterator(cend()); }
+
+	_LIBCPP_INLINE_VISIBILITY
+	const_reverse_iterator crend()    const _NOEXCEPT { return const_reverse_iterator(cbegin()); }
+
+	// [string.view.capacity], capacity
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	size_type size()     const _NOEXCEPT { return __size; }
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	size_type length()   const _NOEXCEPT { return __size; }
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	size_type max_size() const _NOEXCEPT { return numeric_limits<size_type>::max(); }
+
+	_LIBCPP_CONSTEXPR bool _LIBCPP_INLINE_VISIBILITY
+	empty()         const _NOEXCEPT { return __size == 0; }
+
+	// [string.view.access], element access
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_reference operator[](size_type __pos) const _NOEXCEPT { return __data[__pos]; }
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_reference at(size_type __pos) const
+	{
+		return __pos >= size()
+			? (__libcpp_throw(out_of_range("string_view::at")), __data[0])
+			: __data[__pos];
+	}
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_reference front() const
+	{
+		return _LIBCPP_ASSERT(!empty(), "string_view::front(): string is empty"), __data[0];
+	}
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_reference back() const
+	{
+		return _LIBCPP_ASSERT(!empty(), "string_view::back(): string is empty"), __data[__size-1];
+	}
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	const_pointer data() const _NOEXCEPT { return __data; }
+
+	// [string.view.modifiers], modifiers:
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	void clear() _NOEXCEPT
+	{
+		__data = nullptr;
+		__size = 0;
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	void remove_prefix(size_type __n) _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__n <= size(), "remove_prefix() can't remove more than size()");
+		__data += __n;
+		__size -= __n;
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	void remove_suffix(size_type __n) _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__n <= size(), "remove_suffix() can't remove more than size()");
+		__size -= __n;
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	void swap(basic_string_view& __other) _NOEXCEPT
+	{
+		const value_type *__p = __data;
+		__data = __other.__data;
+		__other.__data = __p;
+
+		size_type __sz = __size;
+		__size = __other.__size;
+		__other.__size = __sz;
+	}
+
+	_LIBCPP_INLINE_VISIBILITY
+	size_type copy(_CharT* __s, size_type __n, size_type __pos = 0) const
+	{
+		if (__pos > size())
+			__libcpp_throw(out_of_range("string_view::copy"));
+		size_type __rlen = _VSTD::min( __n, size() - __pos );
+		copy_n(begin() + __pos, __rlen, __s );
+		return __rlen;
+	}
+
+	_LIBCPP_CONSTEXPR _LIBCPP_INLINE_VISIBILITY
+	basic_string_view substr(size_type __pos = 0, size_type __n = npos) const
+	{
+		return __pos > size()
+			? (__libcpp_throw((out_of_range("string_view::substr"))), basic_string_view())
+			: basic_string_view(data() + __pos, _VSTD::min(__n, size() - __pos));
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 int compare(basic_string_view __sv) const _NOEXCEPT
+	{
+		size_type __rlen = _VSTD::min( size(), __sv.size());
+		int __retval = _Traits::compare(data(), __sv.data(), __rlen);
+		if ( __retval == 0 ) // first __rlen chars matched
+			__retval = size() == __sv.size() ? 0 : ( size() < __sv.size() ? -1 : 1 );
+		return __retval;
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	int compare(size_type __pos1, size_type __n1, basic_string_view __sv) const
+	{
+		return substr(__pos1, __n1).compare(__sv);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	int compare(                       size_type __pos1, size_type __n1, 
+				basic_string_view _sv, size_type __pos2, size_type __n2) const
+	{
+		return substr(__pos1, __n1).compare(_sv.substr(__pos2, __n2));
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	int compare(const _CharT* __s) const
+	{
+		return compare(basic_string_view(__s));
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	int compare(size_type __pos1, size_type __n1, const _CharT* __s) const
+	{
+		return substr(__pos1, __n1).compare(basic_string_view(__s));
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	int compare(size_type __pos1, size_type __n1, const _CharT* __s, size_type __n2) const
+	{
+		return substr(__pos1, __n1).compare(basic_string_view(__s, __n2));
+	}
+
+	// find
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): received nullptr");
+		return __str_find<value_type, size_type, traits_type, npos>
+			(data(), size(), __s.data(), __pos, __s.size());
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find(_CharT __c, size_type __pos = 0) const _NOEXCEPT
+	{
+		return __str_find<value_type, size_type, traits_type, npos>
+			(data(), size(), __c, __pos);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find(const _CharT* __s, size_type __pos, size_type __n) const
+	{
+		_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find(): received nullptr");
+		return __str_find<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, __n);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find(const _CharT* __s, size_type __pos = 0) const
+	{
+		_LIBCPP_ASSERT(__s != nullptr, "string_view::find(): received nullptr");
+		return __str_find<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, traits_type::length(__s));
+	}
+
+	// rfind
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type rfind(basic_string_view __s, size_type __pos = npos) const _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find(): received nullptr");
+		return __str_rfind<value_type, size_type, traits_type, npos>
+			(data(), size(), __s.data(), __pos, __s.size());
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type rfind(_CharT __c, size_type __pos = npos) const _NOEXCEPT
+	{
+		return __str_rfind<value_type, size_type, traits_type, npos>
+			(data(), size(), __c, __pos);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type rfind(const _CharT* __s, size_type __pos, size_type __n) const
+	{
+		_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::rfind(): received nullptr");
+		return __str_rfind<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, __n);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type rfind(const _CharT* __s, size_type __pos=npos) const
+	{
+		_LIBCPP_ASSERT(__s != nullptr, "string_view::rfind(): received nullptr");
+		return __str_rfind<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, traits_type::length(__s));
+	}
+
+	// find_first_of
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_of(basic_string_view __s, size_type __pos = 0) const _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_first_of(): received nullptr");
+		return __str_find_first_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s.data(), __pos, __s.size());
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_of(_CharT __c, size_type __pos = 0) const _NOEXCEPT
+	{ return find(__c, __pos); }
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_of(const _CharT* __s, size_type __pos, size_type __n) const
+	{
+		_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_first_of(): received nullptr");
+		return __str_find_first_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, __n);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_of(const _CharT* __s, size_type __pos=0) const
+	{
+		_LIBCPP_ASSERT(__s != nullptr, "string_view::find_first_of(): received nullptr");
+		return __str_find_first_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, traits_type::length(__s));
+	}
+
+	// find_last_of
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_of(basic_string_view __s, size_type __pos=npos) const _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_last_of(): received nullptr");
+		return __str_find_last_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s.data(), __pos, __s.size());
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_of(_CharT __c, size_type __pos = npos) const _NOEXCEPT
+	{ return rfind(__c, __pos); }
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_of(const _CharT* __s, size_type __pos, size_type __n) const
+	{
+		_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_last_of(): received nullptr");
+		return __str_find_last_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, __n);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_of(const _CharT* __s, size_type __pos=npos) const
+	{
+		_LIBCPP_ASSERT(__s != nullptr, "string_view::find_last_of(): received nullptr");
+		return __str_find_last_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, traits_type::length(__s));
+	}
+
+	// find_first_not_of
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_not_of(basic_string_view __s, size_type __pos=0) const _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_first_not_of(): received nullptr");
+		return __str_find_first_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s.data(), __pos, __s.size());
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_not_of(_CharT __c, size_type __pos=0) const _NOEXCEPT
+	{
+		return __str_find_first_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __c, __pos);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const
+	{
+		_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_first_not_of(): received nullptr");
+		return __str_find_first_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, __n);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_first_not_of(const _CharT* __s, size_type __pos=0) const
+	{
+		_LIBCPP_ASSERT(__s != nullptr, "string_view::find_first_not_of(): received nullptr");
+		return __str_find_first_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, traits_type::length(__s));
+	}
+
+	// find_last_not_of
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_not_of(basic_string_view __s, size_type __pos=npos) const _NOEXCEPT
+	{
+		_LIBCPP_ASSERT(__s.size() == 0 || __s.data() != nullptr, "string_view::find_last_not_of(): received nullptr");
+		return __str_find_last_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s.data(), __pos, __s.size());
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_not_of(_CharT __c, size_type __pos=npos) const _NOEXCEPT
+	{
+		return __str_find_last_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __c, __pos);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const
+	{
+		_LIBCPP_ASSERT(__n == 0 || __s != nullptr, "string_view::find_last_not_of(): received nullptr");
+		return __str_find_last_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, __n);
+	}
+
+	_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+	size_type find_last_not_of(const _CharT* __s, size_type __pos=npos) const
+	{
+		_LIBCPP_ASSERT(__s != nullptr, "string_view::find_last_not_of(): received nullptr");
+		return __str_find_last_not_of<value_type, size_type, traits_type, npos>
+			(data(), size(), __s, __pos, traits_type::length(__s));
+	}
+
+private:
+	const   value_type* __data;
+	size_type           __size;
+};
+
+
+// [string.view.comparison]
+// operator ==
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator==(basic_string_view<_CharT, _Traits> __lhs,
+				basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	if ( __lhs.size() != __rhs.size()) return false;
+	return __lhs.compare(__rhs) == 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator==(basic_string_view<_CharT, _Traits> __lhs,
+				typename common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+{
+	if ( __lhs.size() != __rhs.size()) return false;
+	return __lhs.compare(__rhs) == 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator==(typename common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+				basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	if ( __lhs.size() != __rhs.size()) return false;
+	return __lhs.compare(__rhs) == 0;
+}
+
+
+// operator !=
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator!=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	if ( __lhs.size() != __rhs.size())
+		return true;
+	return __lhs.compare(__rhs) != 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator!=(basic_string_view<_CharT, _Traits> __lhs,
+				typename common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+{
+	if ( __lhs.size() != __rhs.size())
+		return true;
+	return __lhs.compare(__rhs) != 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator!=(typename common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+				basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	if ( __lhs.size() != __rhs.size())
+		return true;
+	return __lhs.compare(__rhs) != 0;
+}
+
+
+// operator <
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator<(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) < 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator<(basic_string_view<_CharT, _Traits> __lhs,
+				typename common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) < 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator<(typename common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+				basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) < 0;
+}
+
+
+// operator >
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator> (basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) > 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator>(basic_string_view<_CharT, _Traits> __lhs,
+				typename common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) > 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator>(typename common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+				basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) > 0;
+}
+
+
+// operator <=
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator<=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) <= 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator<=(basic_string_view<_CharT, _Traits> __lhs,
+				typename common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) <= 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator<=(typename common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+				basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) <= 0;
+}
+
+
+// operator >=
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator>=(basic_string_view<_CharT, _Traits> __lhs, basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) >= 0;
+}
+
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator>=(basic_string_view<_CharT, _Traits> __lhs,
+				typename common_type<basic_string_view<_CharT, _Traits> >::type __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) >= 0;
+}
+
+template<class _CharT, class _Traits>
+_LIBCPP_CONSTEXPR_AFTER_CXX11 _LIBCPP_INLINE_VISIBILITY
+bool operator>=(typename common_type<basic_string_view<_CharT, _Traits> >::type __lhs, 
+				basic_string_view<_CharT, _Traits> __rhs) _NOEXCEPT
+{
+	return __lhs.compare(__rhs) >= 0;
+}
+
+typedef basic_string_view<char>     string_view;
+typedef basic_string_view<char16_t> u16string_view;
+typedef basic_string_view<char32_t> u32string_view;
+typedef basic_string_view<wchar_t>  wstring_view;
+
+// [string.view.hash]
+template<class _CharT, class _Traits>
+struct _LIBCPP_TYPE_VIS_ONLY hash<basic_string_view<_CharT, _Traits> >
+    : public unary_function<basic_string_view<_CharT, _Traits>, size_t>
+{
+    size_t operator()(const basic_string_view<_CharT, _Traits> __val) const _NOEXCEPT;
+};
+
+template<class _CharT, class _Traits>
+size_t
+hash<basic_string_view<_CharT, _Traits> >::operator()(
+        const basic_string_view<_CharT, _Traits> __val) const _NOEXCEPT
+{
+    return __do_string_hash(__val.data(), __val.data() + __val.size());
+}
+
+#if _LIBCPP_STD_VER > 11
+
+template <class _CharT, class _Traits>
+__quoted_output_proxy<_CharT, const _CharT *, _Traits>
+quoted (basic_string_view <_CharT, _Traits> __sv,
+             _CharT __delim = _CharT('"'), _CharT __escape=_CharT('\\'))
+{
+    return __quoted_output_proxy<_CharT, const _CharT *, _Traits> 
+         ( __sv.data(), __sv.data() + __sv.size(), __delim, __escape );
+}
+#endif // _LIBCPP_STD_VER > 11
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP_STRING_VIEW