xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator > Class Template Reference

A string that enables heterogeneous lookup when used as a key for hash tables. More...

#include <xentara/utils/string/HashKey.hpp>

Inheritance diagram for xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator >:

Public Member Functions
constexpr	BasicHashKey (const std::basic_string< Char, CharTraits, Allocator > &string)
	Conversion constructor from a regular string.
constexpr	BasicHashKey (std::basic_string< Char, CharTraits, Allocator > &&string) noexcept
	Move-constructor from a regular string.
constexpr auto	operator= (const std::basic_string< Char, CharTraits, Allocator > &string) -> BasicHashKey &
	Assignment operator for a regular string.
constexpr auto	operator= (std::basic_string< Char, CharTraits, Allocator > &&string) noexcept -> BasicHashKey &
	Move-assignment operator for a regular string.
template<typename StringViewLike > requires (std::is_convertible_v<const StringViewLike &, std::basic_string_view<Char, CharTraits>> && !std::is_convertible_v<const StringViewLike &, const Char *>)
constexpr	BasicHashKey (const StringViewLike &string, const Allocator &alloc=Allocator())
	Make this type implicitly constructible from string view-like types.
Public Member Functions inherited from std::basic_string
T	append (T... args)
T	assign (T... args)
T	at (T... args)
T	back (T... args)
T	basic_string (T... args)
T	begin (T... args)
T	c_str (T... args)
T	capacity (T... args)
T	cbegin (T... args)
T	cend (T... args)
T	clear (T... args)
T	compare (T... args)
T	copy (T... args)
T	crbegin (T... args)
T	crend (T... args)
T	data (T... args)
T	empty (T... args)
T	end (T... args)
T	ends_with (T... args)
T	erase (T... args)
T	find (T... args)
T	find_first_not_of (T... args)
T	find_first_of (T... args)
T	find_last_not_of (T... args)
T	find_last_of (T... args)
T	front (T... args)
T	get_allocator (T... args)
T	insert (T... args)
T	length (T... args)
T	max_size (T... args)
T	operator basic_string_view (T... args)
T	operator+= (T... args)
T	operator= (T... args)
T	operator[] (T... args)
T	pop_back (T... args)
T	push_back (T... args)
T	rbegin (T... args)
T	rend (T... args)
T	replace (T... args)
T	reserve (T... args)
T	resize (T... args)
T	rfind (T... args)
T	shrink_to_fit (T... args)
T	size (T... args)
T	starts_with (T... args)
T	substr (T... args)
T	swap (T... args)

Detailed Description

template<typename Char, typename CharTraits = std::char_traits<Char>, typename Allocator = std::allocator<Char>>
class xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator >

A string that enables heterogeneous lookup when used as a key for hash tables.

This class can be used as a key for std::unordered_map and std::unordered_set to enable heterogeneous lookup, allowing you to look up an entry in a hash table using any type convertible to std::basic_string_view as lookup key, not just BasicHashKey. This saves you from having to construct a string just to perform a lookup, which can lead to unwanted heap allocations. To accomplish this, this class does two things:

1. std::hash<xentara::utils::string::BasicHashKey "std::hash<BasicHashKey>" is a transparent hash, allowing any object convertible to std::basic_string_view to be hashed.
2. BasicHashKey is implicitly constructible from any object convertible to std::basic_string_view. This is necessary for functions like std::unordered_map::try_emplace() to function correctly.

Constructor & Destructor Documentation

BasicHashKey() [1/3]

template<typename Char , typename CharTraits = std::char_traits<Char>, typename Allocator = std::allocator<Char>>

constexpr xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator >::BasicHashKey ( const std::basic_string< Char, CharTraits, Allocator > &  string )

constexpr

Conversion constructor from a regular string.

BasicHashKey() [2/3]

template<typename Char , typename CharTraits = std::char_traits<Char>, typename Allocator = std::allocator<Char>>

constexpr xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator >::BasicHashKey ( std::basic_string< Char, CharTraits, Allocator > &&  string )

constexprnoexcept

Move-constructor from a regular string.

BasicHashKey() [3/3]

template<typename Char , typename CharTraits = std::char_traits<Char>, typename Allocator = std::allocator<Char>>

template<typename StringViewLike >
requires (std::is_convertible_v<const StringViewLike &, std::basic_string_view<Char, CharTraits>> && !std::is_convertible_v<const StringViewLike &, const Char *>)

constexpr xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator >::BasicHashKey ( const StringViewLike &  string, const Allocator &  alloc = Allocator()  )

constexpr

Make this type implicitly constructible from string view-like types.

Member Function Documentation

operator=() [1/2]

template<typename Char , typename CharTraits = std::char_traits<Char>, typename Allocator = std::allocator<Char>>

constexpr auto xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator >::operator= ( const std::basic_string< Char, CharTraits, Allocator > &  string ) -> BasicHashKey &

constexpr

Assignment operator for a regular string.

operator=() [2/2]

template<typename Char , typename CharTraits = std::char_traits<Char>, typename Allocator = std::allocator<Char>>

constexpr auto xentara::utils::string::BasicHashKey< Char, CharTraits, Allocator >::operator= ( std::basic_string< Char, CharTraits, Allocator > &&  string ) -> BasicHashKey &

constexprnoexcept

Move-assignment operator for a regular string.