Trying something out of my comfort here, and attempting to implement a D-style range around std::string_view.

Looking for any and all suggestions or improvements.

One of the things I’m not exactly happy about is having to declare difference_type, pointer and reference just to fullfill the forward_iterator concept properly, yet not being able to actually use them.

I feel that this allowing me to initialize a vector straight from the iterator pair is worth the clunkiness, but I welcome any opinion on the subject, or suggestions on how to make it better.

Thanks!

#include <iterator> #include <string_view>  template <typename CharT> struct SplitStringIterator {   using difference_type = std::ptrdiff_t;   using value_type = std::basic_string_view<CharT>;   using pointer = std::basic_string_view<CharT>*;   using reference = std::basic_string_view<CharT>&;   using iterator_category = std::forward_iterator_tag;    SplitStringIterator(value_type str, CharT delim)       : remainder_(str), delim_(delim) {     advance_();   }    SplitStringIterator& operator++() {     advance_();     return *this;   }    SplitStringIterator operator++(int) {     SplitStringIterator other = *this;     advance_();     return other;   }    value_type operator*() const { return sub_str_; }    bool operator==(SplitStringIterator const& rhs) const {     return sub_str_.data() == rhs.sub_str_.data() &&            remainder_.data() == rhs.remainder_.data() && delim_ == delim_;   }    bool operator!=(SplitStringIterator const& rhs) const {     return !(*this == rhs);   }   private:   value_type sub_str_;   value_type remainder_;   const CharT delim_;    void advance_() {     auto delim_pos = remainder_.find(delim_);      if (delim_pos == value_type::npos) {       sub_str_ = remainder_;       remainder_ = value_type();     } else {       sub_str_ = value_type(&*remainder_.begin(), delim_pos);       remainder_.remove_prefix(delim_pos + 1);     }   } };  template <typename CharT> struct SplitString {   SplitString(std::basic_string_view<CharT> src, CharT d)       : source(src), delim(d) {}    std::basic_string_view<CharT> source;   CharT delim;    SplitStringIterator<CharT> begin() const {     return SplitStringIterator<CharT>(source, delim);   }    SplitStringIterator<CharT> end() const {     return SplitStringIterator<CharT>(std::basic_string_view<CharT>(), delim);   } };  // Returns a lazy string splitter. template <typename CharT> SplitString<CharT> split(std::basic_string_view<CharT> str, CharT delim) {   return SplitString<CharT>(str, delim); } 

Usage example:

#include <vector> #include <iostream>  void foo() {   std::string data = "aa:bb:cccc";   auto parts = split(std::string_view(data), ':');    for(auto p : parts) {     std::cout << p << std::endl;   }    //if we need random access:   std::vector<std::string_view> parts_indexable(parts.begin(), parts.end()); }