#ifndef STRING_VIEW_H

#define STRING_VIEW_H

#include <string>

#include <stdexcept>

#include <iostream>

class StringView

{

public:

// Constructors

StringView() : data_(nullptr), size_(0) {}

StringView(const char *str) : data_(str), size_(std::char_traits<char>::length(str)) {}

StringView(const std::string &str) : data_(str.data()), size_(str.size()) {}

StringView(const char *str, size_t len) : data_(str), size_(len) {}

const char *data() const { return data_; }

size_t size() const { return size_; }

// Element access

const char &operator[](size_t pos) const

{

return data_[pos];

}

const char &at(size_t pos) const

{

if (pos >= size_)

{

throw std::out_of_range("StringView: out of range");

}

return data_[pos];

}

bool empty() const

{

return size_ == 0;

}

// Substring method

StringView substr(size_t pos, size_t len = std::string::npos) const

{

if (pos > size_)

{

throw std::out_of_range("StringView: out of range");

}

len = std::min(len, size_ - pos);

return StringView(data_ + pos, len);

}

// Comparison operators

bool operator==(const StringView &other) const

{

return size_ == other.size_ && std::equal(data_, data_ + size_, other.data_);

}

bool operator!=(const StringView &other) const

{

return !(*this == other);

}

private:

const char *data_;

size_t size_;

};

#endif // STRING_VIEW_H