real::detail::range_intern_table Struct Reference

Intern table for UTF-8 edge byte ranges, keyed by the exact 16-bit (lo << 8) | hi. More...

#include <lazy_dfa.hpp>

Public Member Functions
constexpr std::uint16_t	find (std::uint16_t key) const noexcept
	Returns the interned class index for key, or absent.
constexpr void	insert (std::uint16_t key, std::uint16_t idx)
	Records idx for key, doubling the table first when it would pass half load.

Static Public Member Functions
static constexpr std::size_t	bucket (std::uint16_t key, std::size_t mask) noexcept
	Probe start for key: Fibonacci hashing — the key times 2^64/phi, keeping the high bits.

Public Attributes
std::vector< std::uint32_t >	slots {std::vector<std::uint32_t>(1024U, 0U)}
	Power of two; 1024 covers the ~476 ranges a \w-heavy program interns without a rehash.
std::size_t	count {0}
	Occupied slots, for the load factor.

Static Public Attributes
static constexpr std::uint16_t	absent {0xFFFFU}
	find's miss answer (never a valid index: it would be slot 0x10000).

Detailed Description

Intern table for UTF-8 edge byte ranges, keyed by the exact 16-bit (lo << 8) | hi.

Open-addressed over a flat buffer, not std::unordered_map: static_storage builds its byte program in a constant expression. A slot holds (key << 16) | (index + 1), so zero means empty and 0x00..0x00 stays a legal key. It grows at half load, never caps: a fixed capacity would fill and spin or silently stop interning.

Member Function Documentation

bucket()

static constexpr std::size_t real::detail::range_intern_table::bucket ( std::uint16_t  key, std::size_t  mask  )

inlinestaticconstexprnoexcept

Probe start for key: Fibonacci hashing — the key times 2^64/phi, keeping the high bits.

Keys arrive in near-runs, so the stride between consecutive keys decides the table's use. Keep the 64-bit product: a shifted 32-bit constant has a stride sharing a factor of 4 with 1024, leaving three buckets in four unreachable. Wrapping is the intended modular multiply.

Parameters

[in]	key	The 16-bit packed byte range.
[in]	mask	slots.size() - 1, the table being a power of two.

Returns

The first bucket to probe.

find()

constexpr std::uint16_t real::detail::range_intern_table::find ( std::uint16_t  key ) const

inlineconstexprnoexcept

Returns the interned class index for key, or absent.

Parameters

[in]

key

The 16-bit packed byte range.

Returns

The class index recorded for key, or absent when it was never interned.

insert()

constexpr void real::detail::range_intern_table::insert ( std::uint16_t  key, std::uint16_t  idx  )

inlineconstexpr

Records idx for key, doubling the table first when it would pass half load.

Parameters

[in]	key	The 16-bit packed byte range.
[in]	idx	The class index to record for it.

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

• include/real/automata/lazy_dfa.hpp