real::detail::name_context_box Class Reference

A uniquely-owning, deep-copying box for owned_name_context that survives constant evaluation. More...

#include <storage.hpp>

Collaboration diagram for real::detail::name_context_box:

Public Member Functions
constexpr	name_context_box () noexcept=default
	Constructs an empty box, owning nothing.
constexpr	name_context_box (const name_context_box &other)
	Deep-copies the other box's context, if it has one.
constexpr	name_context_box (name_context_box &&other) noexcept
	Takes over the other box's context, leaving it empty.
constexpr name_context_box &	operator= (const name_context_box &other)
	Deep-copy assignment.
constexpr name_context_box &	operator= (name_context_box &&other) noexcept
	Move assignment.
constexpr	~name_context_box ()
	Releases the owned context, if any.
constexpr void	emplace (std::string pattern, std::vector< named_group > names)
	Replaces the owned context with one built from pattern and names.
constexpr const owned_name_context *	get () const noexcept
	Returns the owned context, or nullptr when the box is empty.

Private Member Functions
constexpr void	adopt (const owned_name_context &src)
	Allocates and copy-constructs a context from src.
constexpr void	release () noexcept
	Releases the owned context. Precondition: the box owns one.
constexpr void	reset () noexcept
	Destroys and deallocates the owned context, if any.

Private Attributes
owned_name_context *	ptr_ {nullptr}
	The owned context, or nullptr.

Detailed Description

A uniquely-owning, deep-copying box for owned_name_context that survives constant evaluation.

std::shared_ptr is the obvious handle here and cannot be used: a real::regex is constant-evaluable, so the result type it yields must stay literal, and no standard smart pointer is. std::allocator is the only constexpr-usable source in C++20 – the same reason small_vec grows through it – and its blocks are transient, so this releases unconditionally.

Deep copy rather than shared: the box is null on every result that borrows, which is every result a walk or an lvalue regex produces, so nothing on the path that matters ever copies one. What the borrowing path pays is a pointer and a null test.

Constructor & Destructor Documentation

name_context_box() [1/2]

constexpr real::detail::name_context_box::name_context_box ( const name_context_box &  other )

inlineconstexpr

Deep-copies the other box's context, if it has one.

Parameters

[in]

other

The box to copy.

name_context_box() [2/2]

constexpr real::detail::name_context_box::name_context_box ( name_context_box &&  other )

inlineconstexprnoexcept

Takes over the other box's context, leaving it empty.

Parameters

[in,out]

other

The box to move from.

Member Function Documentation

adopt()

constexpr void real::detail::name_context_box::adopt ( const owned_name_context &  src )

inlineconstexprprivate

Allocates and copy-constructs a context from src.

Cold: only a result detached from a temporary regex ever owns a context, and only a copy of one ever reaches here. Left warm it bids for the translation unit's inline budget against the scan routes, and takes it from them – the same non-monotonic budget effect build_byte_program is annotated for.

Parameters

[in]

src

The context to copy.

emplace()

constexpr void real::detail::name_context_box::emplace ( std::string  pattern, std::vector< named_group >  names  )

inlineconstexpr

Replaces the owned context with one built from pattern and names.

Parameters

[in]	pattern	The pattern text to own.
[in]	names	The named-group table to own.

get()

constexpr const owned_name_context * real::detail::name_context_box::get ( ) const

inlineconstexprnoexcept

Returns the owned context, or nullptr when the box is empty.

Returns

The owned context, or nullptr.

operator=() [1/2]

constexpr name_context_box & real::detail::name_context_box::operator= ( const name_context_box &  other )

inlineconstexpr

Deep-copy assignment.

Parameters

[in]

other

The box to copy.

Returns

*this.

operator=() [2/2]

constexpr name_context_box & real::detail::name_context_box::operator= ( name_context_box &&  other )

inlineconstexprnoexcept

Move assignment.

Parameters

[in,out]

other

The box to move from.

Returns

*this.

release()

constexpr void real::detail::name_context_box::release ( )

inlineconstexprprivatenoexcept

Releases the owned context. Precondition: the box owns one.

Split out of reset, and cold for the same reason as the copy path above: every result on the borrowing path runs the null test and nothing else.

---

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

• include/real/storage.hpp