span.hpp

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#ifndef C4_STD_SPAN_HPP_
#define C4_STD_SPAN_HPP_
 
/** @file span.hpp */
 
#ifndef C4CORE_SINGLE_HEADER
#include "c4/language.hpp"
#endif
 
 
#if (C4_CPP >= 20) || defined(__DOXYGEN__)
 
#ifndef C4CORE_SINGLE_HEADER
#include "c4/substr.hpp"
#endif
 
#include <span>
 
 
namespace c4 {
 
template<class T> struct is_string;
template<class T> struct is_writeable_string;
 
// mark std::span<const char> as a string type
template<> struct is_string<std::span<const char>> : public std::true_type {};
template<> struct is_string<const std::span<const char>> : public std::true_type {};
 
// mark std::span<char> as a string type
template<> struct is_string<std::span<char>> : public std::true_type {};
template<> struct is_string<const std::span<char>> : public std::true_type {};
template<> struct is_writeable_string<std::span<char>> : public std::true_type {};
template<> struct is_writeable_string<const std::span<char>> : public std::true_type {};
 
 
//-----------------------------------------------------------------------------
 
/** create a csubstr from an existing std::span<const char> */
C4_ALWAYS_INLINE c4::csubstr to_csubstr(std::span<const char> s) noexcept
{
    return c4::csubstr(s.data(), s.size());
}
 
/** create a csubstr from an existing std::span<char> */
C4_ALWAYS_INLINE c4::csubstr to_csubstr(std::span<char> s) noexcept
{
    return c4::csubstr(s.data(), s.size());
}
/** create a substr from an existing std::span<char> */
C4_ALWAYS_INLINE c4::substr to_substr(std::span<char> s) noexcept
{
    return c4::substr(s.data(), s.size());
}
 
 
//-----------------------------------------------------------------------------
 
C4_ALWAYS_INLINE bool operator== (c4::csubstr ss, std::span<char> s) { return ss.compare(s.data(), s.size()) == 0; }
C4_ALWAYS_INLINE bool operator!= (c4::csubstr ss, std::span<char> s) { return ss.compare(s.data(), s.size()) != 0; }
C4_ALWAYS_INLINE bool operator>= (c4::csubstr ss, std::span<char> s) { return ss.compare(s.data(), s.size()) >= 0; }
C4_ALWAYS_INLINE bool operator>  (c4::csubstr ss, std::span<char> s) { return ss.compare(s.data(), s.size()) >  0; }
C4_ALWAYS_INLINE bool operator<= (c4::csubstr ss, std::span<char> s) { return ss.compare(s.data(), s.size()) <= 0; }
C4_ALWAYS_INLINE bool operator<  (c4::csubstr ss, std::span<char> s) { return ss.compare(s.data(), s.size()) <  0; }
 
C4_ALWAYS_INLINE bool operator== (std::span<char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) == 0; }
C4_ALWAYS_INLINE bool operator!= (std::span<char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) != 0; }
C4_ALWAYS_INLINE bool operator<= (std::span<char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) >= 0; }
C4_ALWAYS_INLINE bool operator<  (std::span<char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) >  0; }
C4_ALWAYS_INLINE bool operator>= (std::span<char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) <= 0; }
C4_ALWAYS_INLINE bool operator>  (std::span<char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) <  0; }
 
 
C4_ALWAYS_INLINE bool operator== (c4::csubstr ss, std::span<const char> s) { return ss.compare(s.data(), s.size()) == 0; }
C4_ALWAYS_INLINE bool operator!= (c4::csubstr ss, std::span<const char> s) { return ss.compare(s.data(), s.size()) != 0; }
C4_ALWAYS_INLINE bool operator>= (c4::csubstr ss, std::span<const char> s) { return ss.compare(s.data(), s.size()) >= 0; }
C4_ALWAYS_INLINE bool operator>  (c4::csubstr ss, std::span<const char> s) { return ss.compare(s.data(), s.size()) >  0; }
C4_ALWAYS_INLINE bool operator<= (c4::csubstr ss, std::span<const char> s) { return ss.compare(s.data(), s.size()) <= 0; }
C4_ALWAYS_INLINE bool operator<  (c4::csubstr ss, std::span<const char> s) { return ss.compare(s.data(), s.size()) <  0; }
 
C4_ALWAYS_INLINE bool operator== (std::span<const char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) == 0; }
C4_ALWAYS_INLINE bool operator!= (std::span<const char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) != 0; }
C4_ALWAYS_INLINE bool operator<= (std::span<const char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) >= 0; }
C4_ALWAYS_INLINE bool operator<  (std::span<const char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) >  0; }
C4_ALWAYS_INLINE bool operator>= (std::span<const char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) <= 0; }
C4_ALWAYS_INLINE bool operator>  (std::span<const char> s, c4::csubstr ss) { return ss.compare(s.data(), s.size()) <  0; }
 
 
//-----------------------------------------------------------------------------
 
/** copy a std::span<const char> to a writeable substr */
C4_ALWAYS_INLINE size_t to_chars(c4::substr buf, std::span<const char> s)
{
    size_t sz = s.size();
    size_t len = buf.len < sz ? buf.len : sz;
    buf.copy_from(csubstr(s.data(), len)); // copy only available chars
    return sz; // return the number of needed chars
}
 
/** copy a std::span<char> to a writeable substr */
inline size_t to_chars(c4::substr buf, std::span<char> s)
{
    size_t sz = s.size();
    size_t len = buf.len < sz ? buf.len : sz;
    buf.copy_from(csubstr(s.data(), len)); // copy only available chars
    return sz; // return the number of needed chars
}
 
/** copy a csubstr to an existing std::span<char> */
inline bool from_chars(c4::csubstr buf, std::span<char> * s)
{
    if(buf.len <= s->size())
    {
        substr(s->data(), buf.len).copy_from(buf);
        *s = s->first(buf.len);
        return true;
    }
    return false;
}
 
} // namespace c4
 
#endif // SPAN_AVAILABLE
 
#endif // C4_STD_SPAN_HPP_