text: /*
     Copyright (c) Marshall Clow 2012-2015.
  
     Distributed under the Boost Software License, Version 1.0. (See accompanying
     file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  
      For more information, see http://www.boost.org
  
      Based on the StringRef implementation in LLVM (http://llvm.org) and
      N3422 by Jeffrey Yasskin
          http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2012/n3442.html
  
  */
  
  #ifndef BOOST_STRING_REF_HPP
  #define BOOST_STRING_REF_HPP
  
  #include <boost/config.hpp>
  #include <boost/detail/workaround.hpp>
  #include <boost/utility/string_ref_fwd.hpp>
  #include <boost/throw_exception.hpp>
  
  #include <cstddef>
  #include <stdexcept>
  #include <algorithm>
  #include <iterator>
  #include <string>
  #include <iosfwd>
  
  #if defined(BOOST_NO_CXX11_DEFAULTED_FUNCTIONS) || (defined(BOOST_GCC) && ((BOOST_GCC+0) / 100) <= 406)
  // GCC 4.6 cannot handle a defaulted function with noexcept specifier
  #define BOOST_STRING_REF_NO_CXX11_DEFAULTED_NOEXCEPT_FUNCTIONS
  #endif
  
  namespace boost {
  
      namespace detail {
      //  A helper functor because sometimes we don't have lambdas
          template <typename charT, typename traits>
          class string_ref_traits_eq {
          public:
              string_ref_traits_eq ( charT ch ) : ch_(ch) {}
              bool operator () ( charT val ) const { return traits::eq ( ch_, val ); }
              charT ch_;
              };
          }
  
      template<typename charT, typename traits>
      class basic_string_ref {
      public:
          // types
          typedef charT value_type;
          typedef const charT* pointer;
          typedef const charT& reference;
          typedef const charT& const_reference;
          typedef pointer const_iterator; // impl-defined
          typedef const_iterator iterator;
          typedef std::reverse_iterator<const_iterator> const_reverse_iterator;
          typedef const_reverse_iterator reverse_iterator;
          typedef std::size_t size_type;
          typedef std::ptrdiff_t difference_type;
          static BOOST_CONSTEXPR_OR_CONST size_type npos = size_type(-1);
  
          // construct/copy
          BOOST_CONSTEXPR basic_string_ref () BOOST_NOEXCEPT
              : ptr_(NULL), len_(0) {}
  
          // by defaulting these functions, basic_string_ref becomes
          //  trivially copy/move constructible.
          BOOST_CONSTEXPR basic_string_ref (const basic_string_ref &rhs) BOOST_NOEXCEPT
  #ifndef BOOST_STRING_REF_NO_CXX11_DEFAULTED_NOEXCEPT_FUNCTIONS
              = default;
  #else
              : ptr_(rhs.ptr_), len_(rhs.len_) {}
  #endif
  
          basic_string_ref& operator=(const basic_string_ref &rhs) BOOST_NOEXCEPT
  #ifndef BOOST_STRING_REF_NO_CXX11_DEFAULTED_NOEXCEPT_FUNCTIONS
              = default;
  #else
              {
              ptr_ = rhs.ptr_;
              len_ = rhs.len_;
              return *this;
              }
  #endif
  
          basic_string_ref(const charT* str) BOOST_NOEXCEPT
              : ptr_(str), len_(traits::length(str)) {}
  
          template<typename Allocator>
          basic_string_ref(const std::basic_string<charT, traits, Allocator>& str)
              : ptr_(str.data()), len_(str.length()) {}
  
  // #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
  //         // Constructing a string_ref from a temporary string is a bad idea
  //         template<typename Allocator>
  //         basic_string_ref(      std::basic_string<charT, traits, Allocator>&&)
  //             = delete;
  // #endif
  
          BOOST_CONSTEXPR basic_string_ref(const charT* str, size_type len) BOOST_NOEXCEPT
              : ptr_(str), len_(len) {}
  
  #ifndef BOOST_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS
          template<typename Allocator>
          explicit operator std::basic_string<charT, traits, Allocator>() const {
              return std::basic_string<charT, traits, Allocator> ( begin(), end());
              }
  #endif
  
          std::basic_string<charT, traits> to_string () const {
              return std::basic_string<charT, traits> ( begin(), end());
              }
  
          // iterators
          BOOST_CONSTEXPR const_iterator   begin() const { return ptr_; }
          BOOST_CONSTEXPR const_iterator  cbegin() const { return ptr_; }
          BOOST_CONSTEXPR const_iterator     end() const { return ptr_ + len_; }
          BOOST_CONSTEXPR const_iterator    cend() const { return ptr_ + len_; }
                  const_reverse_iterator  rbegin() const { return const_reverse_iterator (end()); }
                  const_reverse_iterator crbegin() const { return const_reverse_iterator (end()); }
                  const_reverse_iterator    rend() const { return const_reverse_iterator (begin()); }
                  const_reverse_iterator   crend() const { return const_reverse_iterator (begin()); }
  
          // capacity
          BOOST_CONSTEXPR size_type size()     const { return len_; }
          BOOST_CONSTEXPR size_type length()   const { return len_; }
          BOOST_CONSTEXPR size_type max_size() const { return len_; }
          BOOST_CONSTEXPR bool empty()         const { return len_ == 0; }
  
          // element access
          BOOST_CONSTEXPR const charT& operator[](size_type pos) const { return ptr_[pos]; }
  
          const charT& at(size_t pos) const {
              if ( pos >= len_ )
                  BOOST_THROW_EXCEPTION( std::out_of_range ( "boost::string_ref::at" ) );
              return ptr_[pos];
              }
  
          BOOST_CONSTEXPR const charT& front() const { return ptr_[0]; }
          BOOST_CONSTEXPR const charT& back()  const { return ptr_[len_-1]; }
          BOOST_CONSTEXPR const charT* data()  const { return ptr_; }
  
          // modifiers
          void clear() { len_ = 0; }
          void remove_prefix(size_type n) {
              if ( n > len_ )
                  n = len_;
              ptr_ += n;
              len_ -= n;
              }
  
          void remove_suffix(size_type n) {
              if ( n > len_ )
                  n = len_;
              len_ -= n;
              }
  
  
          // basic_string_ref string operations
          basic_string_ref substr(size_type pos, size_type n=npos) const {
              if ( pos > size())
                  BOOST_THROW_EXCEPTION( std::out_of_range ( "string_ref::substr" ) );
              return basic_string_ref(data() + pos, (std::min)(size() - pos, n));
              }
  
          int compare(basic_string_ref x) const {
              const int cmp = traits::compare ( ptr_, x.ptr_, (std::min)(len_, x.len_));
              return cmp != 0 ? cmp : ( len_ == x.len_ ? 0 : len_ < x.len_ ? -1 : 1 );
              }
  
          bool starts_with(charT c) const { return !empty() && traits::eq ( c, front()); }
          bool starts_with(basic_string_ref x) const {
              return len_ >= x.len_ && traits::compare ( ptr_, x.ptr_, x.len_ ) == 0;
              }
  
          bool ends_with(charT c) const { return !empty() && traits::eq ( c, back()); }
          bool ends_with(basic_string_ref x) const {
              return len_ >= x.len_ && traits::compare ( ptr_ + len_ - x.len_, x.ptr_, x.len_ ) == 0;
              }
  
          size_type find(basic_string_ref s) const {
              const_iterator iter = std::search ( this->cbegin (), this->cend (),
                                                  s.cbegin (), s.cend (), traits::eq );
              return iter == this->cend () ? npos : std::distance ( this->cbegin (), iter );
              }
  
          size_type find(charT c) const {
              const_iterator iter = std::find_if ( this->cbegin (), this->cend (),
                                      detail::string_ref_traits_eq<charT, traits> ( c ));
              return iter == this->cend () ? npos : std::distance ( this->cbegin (), iter );
              }
  
          size_type rfind(basic_string_ref s) const {
              const_reverse_iterator iter = std::search ( this->crbegin (), this->crend (),
                                                  s.crbegin (), s.crend (), traits::eq );
              return iter == this->crend () ? npos : (std::distance(iter, this->crend()) - s.size());
              }
  
          size_type rfind(charT c) const {
              const_reverse_iterator iter = std::find_if ( this->crbegin (), this->crend (),
                                      detail::string_ref_traits_eq<charT, traits> ( c ));
              return iter == this->crend () ? npos : (this->size() - 1 - std::distance(this->crbegin(), iter));
              }
  
          size_type find_first_of(charT c) const { return  find (c); }
          size_type find_last_of (charT c) const { return rfind (c); }
  
          size_type find_first_of(basic_string_ref s) const {
              const_iterator iter = std::find_first_of
                  ( this->cbegin (), this->cend (), s.cbegin (), s.cend (), traits::eq );
              return iter == this->cend () ? npos : std::distance ( this->cbegin (), iter );
              }
  
          size_type find_last_of(basic_string_ref s) const {
              const_reverse_iterator iter = std::find_first_of
                  ( this->crbegin (), this->crend (), s.cbegin (), s.cend (), traits::eq );
              return iter == this->crend () ? npos : (this->size() - 1 - std::distance(this->crbegin(), iter));
              }
  
          size_type find_first_not_of(basic_string_ref s) const {
              const_iterator iter = find_not_of ( this->cbegin (), this->cend (), s );
              return iter == this->cend () ? npos : std::distance ( this->cbegin (), iter );
              }
  
          size_type find_first_not_of(charT c) const {
              for ( const_iterator iter = this->cbegin (); iter != this->cend (); ++iter )
                  if ( !traits::eq ( c, *iter ))
                      return std::distance ( this->cbegin (), iter );
              return npos;
              }
  
          size_type find_last_not_of(basic_string_ref s) const {
              const_reverse_iterator iter = find_not_of ( this->crbegin (), this->crend (), s );
              return iter == this->crend () ? npos : (this->size() - 1 - std::distance(this->crbegin(), iter));
              }
  
          size_type find_last_not_of(charT c) const {
              for ( const_reverse_iterator iter = this->crbegin (); iter != this->crend (); ++iter )
                  if ( !traits::eq ( c, *iter ))
                      return this->size() - 1 - std::distance(this->crbegin(), iter);
              return npos;
              }
  
      private:
  
          template <typename Iterator>
          Iterator find_not_of ( Iterator first, Iterator last, basic_string_ref s ) const {
              for ( ; first != last ; ++first )
                  if ( 0 == traits::find ( s.ptr_, s.len_, *first ))
                      return first;
              return last;
              }
  
  
  
          const charT *ptr_;
          std::size_t len_;
          };
  
  
  //  Comparison operators
  //  Equality
      template<typename charT, typename traits>
      inline bool operator==(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          if ( x.size () != y.size ()) return false;
          return x.compare(y) == 0;
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator==(basic_string_ref<charT, traits> x, const std::basic_string<charT, traits, Allocator> & y) {
          return x == basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator==(const std::basic_string<charT, traits, Allocator> & x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) == y;
          }
  
      template<typename charT, typename traits>
      inline bool operator==(basic_string_ref<charT, traits> x, const charT * y) {
          return x == basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits>
      inline bool operator==(const charT * x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) == y;
          }
  
  //  Inequality
      template<typename charT, typename traits>
      inline bool operator!=(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          if ( x.size () != y.size ()) return true;
          return x.compare(y) != 0;
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator!=(basic_string_ref<charT, traits> x, const std::basic_string<charT, traits, Allocator> & y) {
          return x != basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator!=(const std::basic_string<charT, traits, Allocator> & x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) != y;
          }
  
      template<typename charT, typename traits>
      inline bool operator!=(basic_string_ref<charT, traits> x, const charT * y) {
          return x != basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits>
      inline bool operator!=(const charT * x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) != y;
          }
  
  //  Less than
      template<typename charT, typename traits>
      inline bool operator<(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) < 0;
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator<(basic_string_ref<charT, traits> x, const std::basic_string<charT, traits, Allocator> & y) {
          return x < basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator<(const std::basic_string<charT, traits, Allocator> & x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) < y;
          }
  
      template<typename charT, typename traits>
      inline bool operator<(basic_string_ref<charT, traits> x, const charT * y) {
          return x < basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits>
      inline bool operator<(const charT * x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) < y;
          }
  
  //  Greater than
      template<typename charT, typename traits>
      inline bool operator>(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) > 0;
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator>(basic_string_ref<charT, traits> x, const std::basic_string<charT, traits, Allocator> & y) {
          return x > basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator>(const std::basic_string<charT, traits, Allocator> & x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) > y;
          }
  
      template<typename charT, typename traits>
      inline bool operator>(basic_string_ref<charT, traits> x, const charT * y) {
          return x > basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits>
      inline bool operator>(const charT * x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) > y;
          }
  
  //  Less than or equal to
      template<typename charT, typename traits>
      inline bool operator<=(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) <= 0;
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator<=(basic_string_ref<charT, traits> x, const std::basic_string<charT, traits, Allocator> & y) {
          return x <= basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator<=(const std::basic_string<charT, traits, Allocator> & x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) <= y;
          }
  
      template<typename charT, typename traits>
      inline bool operator<=(basic_string_ref<charT, traits> x, const charT * y) {
          return x <= basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits>
      inline bool operator<=(const charT * x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) <= y;
          }
  
  //  Greater than or equal to
      template<typename charT, typename traits>
      inline bool operator>=(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) >= 0;
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator>=(basic_string_ref<charT, traits> x, const std::basic_string<charT, traits, Allocator> & y) {
          return x >= basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits, typename Allocator>
      inline bool operator>=(const std::basic_string<charT, traits, Allocator> & x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) >= y;
          }
  
      template<typename charT, typename traits>
      inline bool operator>=(basic_string_ref<charT, traits> x, const charT * y) {
          return x >= basic_string_ref<charT, traits>(y);
          }
  
      template<typename charT, typename traits>
      inline bool operator>=(const charT * x, basic_string_ref<charT, traits> y) {
          return basic_string_ref<charT, traits>(x) >= y;
          }
  
      namespace detail {
  
          template<class charT, class traits>
          inline void sr_insert_fill_chars(std::basic_ostream<charT, traits>& os, std::size_t n) {
              enum { chunk_size = 8 };
              charT fill_chars[chunk_size];
              std::fill_n(fill_chars, static_cast< std::size_t >(chunk_size), os.fill());
              for (; n >= chunk_size && os.good(); n -= chunk_size)
                  os.write(fill_chars, static_cast< std::size_t >(chunk_size));
              if (n > 0 && os.good())
                  os.write(fill_chars, n);
              }
  
          template<class charT, class traits>
          void sr_insert_aligned(std::basic_ostream<charT, traits>& os, const basic_string_ref<charT,traits>& str) {
              const std::size_t size = str.size();
              const std::size_t alignment_size = static_cast< std::size_t >(os.width()) - size;
              const bool align_left = (os.flags() & std::basic_ostream<charT, traits>::adjustfield) == std::basic_ostream<charT, traits>::left;
              if (!align_left) {
                  detail::sr_insert_fill_chars(os, alignment_size);
                  if (os.good())
                      os.write(str.data(), size);
                  }
              else {
                  os.write(str.data(), size);
                  if (os.good())
                      detail::sr_insert_fill_chars(os, alignment_size);
                  }
              }
  
          } // namespace detail
  
      // Inserter
      template<class charT, class traits>
      inline std::basic_ostream<charT, traits>&
      operator<<(std::basic_ostream<charT, traits>& os, const basic_string_ref<charT,traits>& str) {
          if (os.good()) {
              const std::size_t size = str.size();
              const std::size_t w = static_cast< std::size_t >(os.width());
              if (w <= size)
                  os.write(str.data(), size);
              else
                  detail::sr_insert_aligned(os, str);
              os.width(0);
              }
          return os;
          }
  
  #if 0
      // numeric conversions
      //
      //  These are short-term implementations.
      //  In a production environment, I would rather avoid the copying.
      //
      inline int stoi (string_ref str, size_t* idx=0, int base=10) {
          return std::stoi ( std::string(str), idx, base );
          }
  
      inline long stol (string_ref str, size_t* idx=0, int base=10) {
          return std::stol ( std::string(str), idx, base );
          }
  
      inline unsigned long stoul (string_ref str, size_t* idx=0, int base=10) {
          return std::stoul ( std::string(str), idx, base );
          }
  
      inline long long stoll (string_ref str, size_t* idx=0, int base=10) {
          return std::stoll ( std::string(str), idx, base );
          }
  
      inline unsigned long long stoull (string_ref str, size_t* idx=0, int base=10) {
          return std::stoull ( std::string(str), idx, base );
          }
  
      inline float stof (string_ref str, size_t* idx=0) {
          return std::stof ( std::string(str), idx );
          }
  
      inline double stod (string_ref str, size_t* idx=0) {
          return std::stod ( std::string(str), idx );
          }
  
      inline long double stold (string_ref str, size_t* idx=0)  {
          return std::stold ( std::string(str), idx );
          }
  
      inline int  stoi (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoi ( std::wstring(str), idx, base );
          }
  
      inline long stol (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stol ( std::wstring(str), idx, base );
          }
  
      inline unsigned long stoul (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoul ( std::wstring(str), idx, base );
          }
  
      inline long long stoll (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoll ( std::wstring(str), idx, base );
          }
  
      inline unsigned long long stoull (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoull ( std::wstring(str), idx, base );
          }
  
      inline float  stof (wstring_ref str, size_t* idx=0) {
          return std::stof ( std::wstring(str), idx );
          }
  
      inline double stod (wstring_ref str, size_t* idx=0) {
          return std::stod ( std::wstring(str), idx );
          }
  
      inline long double stold (wstring_ref str, size_t* idx=0) {
          return std::stold ( std::wstring(str), idx );
          }
  #endif
  
  }
  
  #if 0
  namespace std {
      // Hashing
      template<> struct hash<boost::string_ref>;
      template<> struct hash<boost::u16string_ref>;
      template<> struct hash<boost::u32string_ref>;
      template<> struct hash<boost::wstring_ref>;
  }
  #endif
  
  #endif
  