pqxx::zview Class Reference

Marker-type wrapper: zero-terminated std::string_view. More...

#include <zview.hxx>

Inheritance diagram for pqxx::zview:

Collaboration diagram for pqxx::zview:

Public Member Functions
constexpr	zview () noexcept
	Default constructor produces a zero-terminated empty string. More...
constexpr PQXX_ZARGS	zview (char const text[], std::ptrdiff_t len) noexcept(noexcept(std::string_view{text, static_cast< std::size_t >(len)}))
	Convenience overload: construct using pointer and signed length. More...
constexpr	zview (char text[], std::ptrdiff_t len) noexcept(noexcept(std::string_view{text, static_cast< std::size_t >(len)}))
	Convenience overload: construct using pointer and signed length. More...
constexpr	zview (std::string_view other) noexcept
	Explicitly promote a string_view to a zview. More...
template<typename... Args>
constexpr	zview (Args &&...args)
	Construct from any initialiser you might use for std::string_view. More...
constexpr	zview (std::string const &str) noexcept
constexpr PQXX_ZARGS	zview (char const str[]) noexcept(noexcept(std::string_view{str}))
	Construct a zview from a C-style string. More...
	zview (std::nullptr_t)=delete
template<size_t size>
constexpr PQXX_ZARGS	zview (char const (&literal)[size])
	Construct a zview from a string literal. More...
constexpr char const *	c_str () const &noexcept
	Return as C string. More...
constexpr	operator char const * () const noexcept
	Return as C string. More...
constexpr bool	operator== (zview const &rhs) const noexcept
	Disambiguating comparison operator: leave it to std::string_view. More...
constexpr bool	operator!= (zview const &rhs) const noexcept
	Disambiguating comparison operator: leave it to std::string_view. More...

Detailed Description

Marker-type wrapper: zero-terminated std::string_view.

Warning

Use this only if the underlying string is zero-terminated.

When you construct a zview, you are promising that the data pointer is non-null, and the underlying string is zero-terminated. It otherwise behaves exactly like a std::string_view.

The terminating zero is not "in" the string, so it does not count as part of the view's length.

The added guarantee lets the view be used as a C-style string, which often matters since libpqxx builds on top of a C library. For this reason, zview also adds a c_str method.

Constructor & Destructor Documentation

zview() [1/9]

constexpr pqxx::zview::zview ( )

inlineconstexprnoexcept

Default constructor produces a zero-terminated empty string.

zview() [2/9]

constexpr PQXX_ZARGS pqxx::zview::zview ( char const  text[], std::ptrdiff_t  len  )

inlineconstexprnoexcept

Convenience overload: construct using pointer and signed length.

Even though you specify the length, there must still be a zero byte just beyond that length, at text[len].

zview() [3/9]

constexpr pqxx::zview::zview ( char  text[], std::ptrdiff_t  len  )

inlineconstexprnoexcept

Convenience overload: construct using pointer and signed length.

zview() [4/9]

constexpr pqxx::zview::zview ( std::string_view  other )

inlineexplicitconstexprnoexcept

Explicitly promote a string_view to a zview.

Warning

This is not just a type conversion. It's the caller making a promise that the string is zero-terminated.

zview() [5/9]

template<typename... Args>

constexpr pqxx::zview::zview ( Args &&...  args )

inlineexplicitconstexpr

Construct from any initialiser you might use for std::string_view.

Warning

Only do this if you are sure that the string is zero-terminated.

zview() [6/9]

constexpr pqxx::zview::zview ( std::string const &  str )

inlineconstexprnoexcept

Warning

There's an implicit conversion from std::string.

zview() [7/9]

constexpr PQXX_ZARGS pqxx::zview::zview ( char const  str[] )

inlineconstexprnoexcept

Construct a zview from a C-style string.

Warning

This scans the string to discover its length. So if you need to do it many times, it's probably better to create the zview once and re-use it.

zview() [8/9]

pqxx::zview::zview ( std::nullptr_t  )

delete

zview() [9/9]

template<size_t size>

constexpr PQXX_ZARGS pqxx::zview::zview ( char const (&)  literal[size] )

inlineconstexpr

Construct a zview from a string literal.

A C++ string literal ("foo") normally looks a lot like a pointer to char const, but that's not really true. It's actually an array of char, which devolves to a pointer when you pass it.

For the purpose of creating a zview there is one big difference: if we know the array's size, we don't need to scan through the string in order to find out its length.

Member Function Documentation

c_str()

constexpr char const* pqxx::zview::c_str ( ) const &

inlineconstexprnoexcept

Return as C string.

operator char const *()

constexpr pqxx::zview::operator char const * ( ) const

inlineconstexprnoexcept

Return as C string.

operator!=()

constexpr bool pqxx::zview::operator!= ( zview const &  rhs ) const

inlineconstexprnoexcept

Disambiguating comparison operator: leave it to std::string_view.

operator==()

constexpr bool pqxx::zview::operator== ( zview const &  rhs ) const

inlineconstexprnoexcept

Disambiguating comparison operator: leave it to std::string_view.

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The documentation for this class was generated from the following file:

• include/pqxx/zview.hxx