text: /* 
     Copyright (c) Marshall Clow 2012-2012.
  
     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 <stdexcept>
  #include <algorithm>
  #include <functional>
  #include <string>
  #ifndef BOOST_NO_CXX11_HDR_INITIALIZER_LIST
  #include <initializer_list>
  #endif
  
  namespace boost {
      
      namespace detail {
      //  A helper functor for when 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;
      typedef basic_string_ref<char,     std::char_traits<char> >        string_ref;
      typedef basic_string_ref<wchar_t,  std::char_traits<wchar_t> >    wstring_ref;
  
  #ifndef BOOST_NO_CXX11_CHAR16_T
      typedef basic_string_ref<char16_t, std::char_traits<char16_t> > u16string_ref;
  #endif
  
  #ifndef BOOST_NO_CXX11_CHAR32_T
      typedef basic_string_ref<char32_t, std::char_traits<char32_t> > u32string_ref;
  #endif
      
      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 size_t size_type;
          typedef ptrdiff_t difference_type;
          static BOOST_CONSTEXPR_OR_CONST size_type npos = size_type(-1);
          
          // construct/copy
          BOOST_CONSTEXPR basic_string_ref ()
              : ptr_(NULL), len_(0) {}
  
          BOOST_CONSTEXPR basic_string_ref (const basic_string_ref &rhs)
              : ptr_(rhs.ptr_), len_(rhs.len_) {}
  
          basic_string_ref& operator=(const basic_string_ref &rhs) {
              ptr_ = rhs.ptr_;
              len_ = rhs.len_;
              return *this;
              }
              
          basic_string_ref(const charT* str)
              : 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()) {}
  
          BOOST_CONSTEXPR basic_string_ref(const charT* str, size_type len)
              : ptr_(str), len_(len) {}
  
  #ifndef BOOST_NO_CXX11_HDR_INITIALIZER_LIST
  //  !! How do I do this? Look how initializer_lists work!
          basic_string_ref(std::initializer_list<charT> il);  // TODO
  #endif
  
  #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> ( ptr_, len_ );
              }
  #endif
          
          // 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_ )
                  throw 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
          BOOST_CONSTEXPR
          basic_string_ref substr(size_type pos, size_type n=npos) const {
  //          if ( pos > size()) throw std::out_of_range ( "string_ref::substr" );
  //          if ( n == npos || pos + n > size()) n = size () - pos;
  //          return basic_string_ref ( data() + pos, n );
              return pos > size() ? throw std::out_of_range ( "string_ref::substr" ) :
                  basic_string_ref ( data() + pos, n == npos || pos + n > size() ? size() - pos : n );
              }
          
          int compare(basic_string_ref x) 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() && front() == c; }
          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() && back() == c; }
          bool ends_with(basic_string_ref x) const {
              return len_ >= x.len_ && traits::compare ( ptr_ + len_ - x.len_, x.ptr_, x.len_ ) == 0;
              }
  
  
  //  Have to use traits here
          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 {
  #ifdef BOOST_NO_CXX11_LAMBDAS
              const_iterator iter = std::find_if ( this->cbegin (), this->cend (), 
                                      detail::string_ref_traits_eq<charT, traits> ( c ));
  #else
              const_iterator iter = std::find_if ( this->cbegin (), this->cend (), 
                                      [c] ( charT val ) { return traits::eq ( c, val ); } );
  #endif
              return iter == this->cend () ? npos : std::distance ( this->cbegin (), iter );
              }
                          
          size_type rfind(basic_string_ref s) const {
              const_iterator iter = std::search ( this->crbegin (), this->crend (), 
                                                  s.crbegin (), s.crend (), traits::eq );
              return iter == this->crend () ? npos : reverse_distance ( this->crbegin (), iter );
              }
  
          size_type rfind(charT c) const {
  #ifdef BOOST_NO_CXX11_LAMBDAS
              const_reverse_iterator iter = std::find_if ( this->crbegin (), this->crend (), 
                                      detail::string_ref_traits_eq<charT, traits> ( c ));
  #else
              const_reverse_iterator iter = std::find_if ( this->crbegin (), this->crend (), 
                                      [c] ( charT val ) { return traits::eq ( c, val ); } );
  #endif
              return iter == this->crend () ? npos : reverse_distance ( this->crbegin (), iter );
              }
          
          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_first_of(charT c) const { return  find (c); }
          size_type find_last_of (charT c) const { return rfind (c); }
  
          
          size_type find_last_of(basic_string_ref s) const {
              const_reverse_iterator iter = std::find_first_of ( this->crbegin (), this->crend (), 
                                                  s.crbegin (), s.crend (), traits::eq );
              return iter = this->cend () ? npos : reverse_distance ( this->crbegin (), iter);
              }
          
          size_type find_first_not_of(basic_string_ref s) const {
              for ( const_reverse_iterator iter = this->cbegin (); iter != this->cend (); ++iter )
                  if ( 0 == traits::find ( s->ptr_, s.len_, *iter ))
                      return std::distance ( this->cbegin (), iter );
              return npos;
              }
          
          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 {
              for ( const_reverse_iterator iter = this->crbegin (); iter != this->crend (); ++iter )
                  if ( 0 == traits::find ( s.ptr_, s.len_, *iter ))
                      return reverse_distance ( this->crbegin (), iter );
              return npos;
              }
          
          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 reverse_distance ( this->crbegin (), iter );
              return npos;
              }
  
      private:
          size_type reverse_distance ( reverse_iterator first, reverse_iterator last ) const {
              return len_ - 1 + std::distance ( first, last );
              }
          
          const charT *ptr_;
          std::size_t len_;
          };
      
      // Comparison operators
      template<typename charT, typename traits>
      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>
      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>
      bool operator<(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) < 0;
          }
  
      template<typename charT, typename traits>
      bool operator>(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) > 0;
          }
  
      template<typename charT, typename traits>
      bool operator<=(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) <= 0;
          }
  
      template<typename charT, typename traits>
      bool operator>=(basic_string_ref<charT, traits> x, basic_string_ref<charT, traits> y) {
          return x.compare(y) >= 0;
          }
  
      
      // Inserter
      template<class charT, class traits>
      std::basic_ostream<charT, traits>&
      operator<<(std::basic_ostream<charT, traits>& os, const basic_string_ref<charT,traits>& str) {
  #ifdef BOOST_NO_CXX11_RANGE_BASED_FOR
          for ( typename basic_string_ref<charT, traits>::const_iterator iter = str.begin (); iter != str.end (); ++iter )
              os << *iter;
  #else
          for ( charT x : str )
              os << x;
  #endif
          return os;
          }
      
  #if 0
      // numeric conversions
      //
      //  These are short-term implementations.
      //  In a production environment, I would rather avoid the copying.
      //
      int stoi (string_ref str, size_t* idx=0, int base=10) {
          return std::stoi ( std::string(str), idx, base );
          }
      
      long stol (string_ref str, size_t* idx=0, int base=10) {
          return std::stol ( std::string(str), idx, base );
          }
          
      unsigned long stoul (string_ref str, size_t* idx=0, int base=10) {
          return std::stoul ( std::string(str), idx, base );
          }
          
      long long stoll (string_ref str, size_t* idx=0, int base=10) {
          return std::stoll ( std::string(str), idx, base );
          }
      
      unsigned long long stoull (string_ref str, size_t* idx=0, int base=10) {
          return std::stoull ( std::string(str), idx, base );
          }
      
      float stof (string_ref str, size_t* idx=0) {
          return std::stof ( std::string(str), idx );
          }
          
      double stod (string_ref str, size_t* idx=0) {
          return std::stod ( std::string(str), idx );
          }
          
      long double stold (string_ref str, size_t* idx=0)  {
          return std::stold ( std::string(str), idx );
          }
      
      int  stoi (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoi ( std::wstring(str), idx, base );
          }
          
      long stol (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stol ( std::wstring(str), idx, base );
          }
          
      unsigned long stoul (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoul ( std::wstring(str), idx, base );
          }
          
      long long stoll (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoll ( std::wstring(str), idx, base );
          }
          
      unsigned long long stoull (wstring_ref str, size_t* idx=0, int base=10) {
          return std::stoull ( std::wstring(str), idx, base );
          }
      
      float  stof (wstring_ref str, size_t* idx=0) {
          return std::stof ( std::wstring(str), idx );
          }
          
      double stod (wstring_ref str, size_t* idx=0) {
          return std::stod ( std::wstring(str), idx );
          }
          
      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