fe::SymTab< V, Size > Class Template Reference

A fixed-capacity Symbol -> V map for a closed set of Size entries: filled once, then only looked up - a Lexer's reserved words, say. More...

#include <fe/sym.h>

Public Member Functions
Access
void	emplace (Sym sym, V v)
std::optional< V >	find (Sym sym) const
	Yields nothing if sym is not present - the empty Symbol never is.
bool	contains (Sym sym) const

Static Public Attributes
static constexpr size_t	Capacity = std::bit_ceil(2 * Size)
	Twice Size, rounded up to a power of two, so the load factor stays below 1/2.

Detailed Description

template<class V, size_t Size>
class fe::SymTab< V, Size >

A fixed-capacity Symbol -> V map for a closed set of Size entries: filled once, then only looked up - a Lexer's reserved words, say.

Prefer this over SymMap for that use: both hash and compare the same interned pointer, but SymMap pays a full finalizer and a SwissTable group probe where this pays one multiply and one probe of a table whose capacity is a compile-time constant.

Note

V has to be default-constructible; an absent key yields no V at all - see SymTab::find.

Warning

Insert-only: there is no erase, and SymTab::emplace asserts on a key already present.

Definition at line 253 of file sym.h.

Member Function Documentation

contains()

template<class V, size_t Size>

bool fe::SymTab< V, Size >::contains ( Sym sym ) const

inline

Definition at line 280 of file sym.h.

References find().

emplace()

template<class V, size_t Size>

void fe::SymTab< V, Size >::emplace ( Sym sym, V v )

inline

Definition at line 260 of file sym.h.

References fe::Sym::empty().

find()

template<class V, size_t Size>

std::optional< V > fe::SymTab< V, Size >::find ( Sym sym ) const

inline

Yields nothing if sym is not present - the empty Symbol never is.

Note

The free-slot test comes first: the empty Symbol is a free slot's key.

Definition at line 273 of file sym.h.

References fe::Sym::empty().

Referenced by contains().

Member Data Documentation

Capacity

template<class V, size_t Size>

size_t fe::SymTab< V, Size >::Capacity = std::bit_ceil(2 * Size)

staticconstexpr

Twice Size, rounded up to a power of two, so the load factor stays below 1/2.

Definition at line 256 of file sym.h.

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

• fe/sym.h